HomeMy WebLinkAboutTC Ord 1998-08-05 (3)
ORDINANCE NO. 438 N.S.
AN ORDINANCE OF THE TOWN COUNCIL OF THE TOWN OF TffiURON
REPEALING CHAPTER 13C OF THE MUNICIPAL CODE AND ADOPTING BY
REFERENCE THE INDIVIDUAL AND ALTERNATIVE SEWAGE DISPOSAL
SYSTEM REQUIREMENTS OF TITLE 18.06 AND 18.07 OF THE MARIN
COUNTY CODE AS A NEW CHAPTER 13C OF THE MUNICIPAL CODE
(INDIVIDUAL AND AL TERNA TIVE SEW AGE DISPOSAL SYSTEMS)
The Town Council of the Town ofTiburon does hereby ordain as follows:
Section 1. Findings.
A, The Town Council has held public hearings on July 15, 1998 and All~st 5, 1998,
and has received public testimony on this matter.
B. The T own Council finds that all notices and procedures required by law attendant
" to the adoption of this Ordinance have been followed.
...-,.,;
C. The Town Council finds that the repeal and adoption actions made by this
Ordinance are necess~ry for the protection of the public health, safety, and welfare.
D. The Town Council has found that the repeal and adoption actions made by this
Ordinance are consistent with the goals and policies of the Tiburon General Plan
and other adopted ordinances and regulations of the Town of Tiburon.
E. The Town Council finds that this project is categorically exempt from the
requirements of the California Environmental Quality Act per Section 15308 of the
CEQA Guidelines because these regulations constitute an action by a regulatory
agency to assure the maintenance, restoration, enhancement, or protection of the
environment where the regulatory process involves procedures for protection of
the environment.
Section 2. Chapter 13C of the Tiburon Municipal Code Repealed.
Chapter l3C of the Tiburon Municipal Code pertaining to Individual Sewage Disposal
Systems is hereby repealed.
Section 3. Chapter t3C of the Tiburon Municipal Code Adopted.
A new Chapter l3C of the Tiburon Municipal Code pertaining to Individual Sewage
Disposal Systems and Alternative Sewage Disposal Systems is hereby adopted as follows:
Town of Tihl/rOI1 Ordinance No. 438 N. S. Effective 9/4/98
1
CHAPTER 13C
INDIVIDUAL AND ALTERNATIVE SEWAGE DISPOSAL SYSTEMS
Sec. 13C-1. Adoption of County Code for Individual Sewage Disposal Systems.
Pursuant to Government Code Section 50022.9, the Marin County Individual
Sewage Disposal System ordinance set forth in Title 18 of the Marin County Code,
Chapter 18.06, including all current amendments thereto, and the Regulations For
Design, Construction, and Repair of Individual Sewage Disposal Systems issued
pursuant to Section 18.06.060, are adopted by reference and shall be in full force
and effect within the Town of Tiburon with the following exceptions:
1. Section 18.06.020 regarding Applicability shall be amended to expand
... .. the applicability of Chapter 18.06 to include all territol1.' within the
corporate limits of the Town of Tiburon.
2. Notwithstanding provisions of Section 18.06.050 to the contrary, the
~ Health Officer shall not accept for filing any application requesting
. ,-:",t tbe installation of any Individual Sewage Disposal System on any
unimproved lot within the Town of Tiburon unless the Town's zoning
requirement for connection to a Public Sewer System has been
,
specifically exempted by vote of the Town Council, and written
documentation to that effect is provided with the application.
If any such application is erroneously accepted for filing without
demonstration of the Town Council's exemption, then the Health
Officer shall not authorize or permit the installation of any Individual
Sewage Disposal System on any unimproved lot within the Town of
Tiburon unless the Town's requirement for connection to a Public
Sewer System has been specifically exempted by vote of the Town
Council.
For purposes of this section, "unimproved lot" shall mean a holding of
real property which is not improved with a primary building such as a
dwelling unit or place of business.
3. Section 18.06.150 (Penalty for Violations) is deleted.
Section 13C-2. Adoption of County Code for Alternative Sewage Disposal Systems.
Pursuant to Government Code Section 50022.9, the Marin County Alternative
Sewage Disposal System ordinance set forth in Title 18 of the Marin County Code,
Chapter 18.07, including all current amendments thereto, and the Regulations for
Town of Tihuroll Ordinance No. 438 N. S. Effective 9/4/98
2
Design, Construction, and Repair of Individual Sewage Disposal Systems, Section
800, issued pursuant to Section 18.07.060, are adopted by reference and shall be in
full force and effect within the Town ofTiburon with the following exceptions:
1. Section 18.07.020 regarding Applicability shall be amended to expand
the applicability of Chapter 18.07 to include all territory within the
corporate limits of the Town ofTiburon.
2. Notwithstanding provisions of Section 18.07.050 to the contrary, the
Health Officer shall not accept for filing any application requesting
the installation of any Individual Sewage Disposal System on any
unimproved lot within the Town ofTiburon unless the Town's zoning
requirement for connection to a Public Sanitary Sewer System has
'" -. been specifically exempted by vote of the Town Council, and written
documentation to that effect is provided with the application.
If any such application is erroneously accepted for filing without
- demonstration of the Town Council's exemption, then the Health
. _T"" Officer shall not authorize or permit the installation of any Individual
Sewage Disposal System on any unimproved lot within the Town of
Tiburon unless the Town's requirement for connection to a Public
,
Sanitary Sewer System has been specifically exempted by vote of the
Town Council.
For purposes of this section, "unimproved lot" shall mean a holding of
real property which is not improved with a primary building such as a
dwelling unit or place of business.
3. Section 18.07.180 (Penalty for Violations) is deleted.
Sec. 13C-3. Availability of Copies.
Three (3) copies of Chapters 18.06 and 18.07 of the Marin County Code, and
regulations issued pursuant thereto, having been adopted herein by reference, shall
be kept on file for public review in the office of the Tiburon Town Clerk.
Sec. 13C-4. Enforcement.
Any violation of the provisions of this chapter is hereby declared a public nuisance
and shall be subject to summary abatement as provided by law.
Any person violating provisions of this chapter, or violating any conditions of a
permit issued under this chapter, shall be deemed guilty of an infraction and shall
Town of Tiburon Ordinance No. 438 N. S. Effective 9/4/98
3
be subject to penalties pursuant to Section 36900 of the Government Code, as
amended.
Each and every day that any violation of this chapter continues, is committed or is
permitted shall be regarded as a new and separate offense. The remedies provided
in this Section shall be cumulative and not exclusive.
Section 4. Severability.
Should any part or provision of this Ordinance be declared by a court of
competent jurisdiction to be invalid or unconstitutional, such decision shall not
affect the validity of this Ordinance as a whole, or any part thereof except that
part or provision so declared invalid or unconstitutional.
-.. ,."
Section 5. Effective Date.
This Ordinance is to take effect and be in force at the expiration of thirty
~(30) days from and after its passage, and before the expiration of fifteen (15) days
,c"" 'after its passage, the same, or its legally required equivalent, shall be published
with the names of the members voting for and against the same at least once in a
newspaper of general circulation published in the Town of Tiburon.
This Ordinance was introduced at a regular meeting of the Town Council
of the Town of Tiburon on July 15, 1998, and was adopted at a regular meeting of
the Town Council of the Town of Tiburon on August 5, 1998, which was noticed
pursuant to Government Code Section 50022.3, by the following vote:
AYES: COUNCILMEMBERS: Bach, Gram, Hennessy, Matthews
& Thompson
NOES: COUNCILMEMBERS: None
ABSENT: COUNCILMEMBERS: None
7l,,'J. S- 7Il"tt::Ls
HARRY . MATTHEWS, MAYOR
TOWN OF TffiURON
Town of Tiburon OrdilUlnce No. 438 N. S. Effective 9/4/98
4
\ - ,
[ND[VIDUAL SEWAGE DISPOSAL SYSTEMS 18.06.010-18.06.025
Chapter 18.06
INDIVIDUAL SEW AGE DISPOSAL SYSTEMS
Sections :
18.06.0 I 0 Purpose.
18.06.020 Applicability.
W;;;;:f'>i~)1\ J~;Q) 18.06.025 Coastal zone.
.i-:t.:l.... ~':;""'i:J ,j ::........ . 18.06.030 DefInitions.
TCVVN OF Ti3URON 18.06.040 Prohibited acts.
[ 8.06.050 Connection to public sewer system and alternatives.
/\PR S 1998 18.06.055 Building permit approval.
18.06.060 Regulations.
crT\~-"-\'''''C''' 18.06.066 Permit required.
'':i ,",i"l ~ ,~.;,::::.;\; i 'r
C'""~ r., ro H "-,"\" 1""-' ''--; """....~ ~-~.- 18.06.070 Application and fees.
v;:J;;Vd...ii"H I I' W::Vt;L\.,;I"j..';:.::~! j 18.06.080 Health 0 fficer review.
18.06.082 Permits- No n transf era b Ie.
18.06.084 Permits-Revocation.
18.06.090 Certificate of inspection.
18.06.[00 Biennial inspection and renewal.
18.06.110 Recordation and transfer of certificate.
18.06.120 Defective systems.
18.06.125 Abandoned sewage disposal facilities.
18.06.130 Enforcement.
18.06.140 Appeals.
18.06.150 Penalty for violations.
18.06.160 Severability.
18.06.010 Purpose. The provisions of this chapter are intended to
insure that the disposal of sewage shall be accomplished in a safe and sani-
tary manner in order to protect the public health, safety and welfare to the
greatest extent possible. (Ord. 1861 ~ I (part), 1971).
18.06.020 Applicability. This chapter is applicable to all existing and
new individual sewage disposal systems in the unicorporated area of Marin
County. However, where a governmental entity has entered into an agree-
ment with the board of supervisors to assume responsibility for regulating
or issuing permits to construct, alter, modify or replace individual sewage
systems, then the provisions of this chapter shall not apply within the juris-
dictional limits of that entity for the scope of responsibility assumed by the
entity. (Ord. 2960 ~ 1,1987: Ord. 2842 ~ 1,1984: Ord. 1861 ~ I (part),
1971).
18.06.025 Coastal zone. Any sewage disposal systems proposed within
the coastal zone, as defmed by the Coastal Act of 1976, may be subject to
a coastal development permit pursuant to Chapters 22.5 6 and 22.57 of this
code. Different standards, as set forth in Chapters 22.56 and 22.57, are ap-
plicable to projects located in coastal districts. COrd. 2637 ~ 4, 1981).
272.1 (Marin County 1-88)
- -
18.06.030-18.06.040 SEWERS
18.06.030 Definitions. CHEMICAL' TOILET. The term "chemical
toilet" means and includes any toilet constructed, installed or placed for the
purpose of depositing therein sewage which is disposed of other than by
discharge directly into a public sewer system, or individual sewage disposal
system approved by the health officer. .
HEALTH OFFICER. The term "health officer" means the Marin
County health officer or his authorized representatives.
INDIVIDUAL SEWAGE DISPOSAL SYSTEM. The term "individual
sewage disposal system" means and includes any system of piping, treatment
devices or other facilities (excluding chemical toilets) that store, convey,
treat or dispose of sewage which is discharged anywhere other than into a
public sewer system.
PERSON. The term "person" includes any person, fIrm, association,
corporation, or any members, agents or employees of the foregoing.
PUBLIC SEWER SYSTEM. The term "pub1ic sewer system" means any
publicly owned and maintained system of sewage conveyance, piping, or any
part thereof, that transports sewage away from the properties of origin to
publicly owned and operated sewage treatment and disposal facilities.
SEW AGE. The term "sewage" means any and all liquid or solid waste
substance, which is associated with human habitation or which contains or
may be contaminated with human or animal excrement or offal. (Ord. 2842
~ 2, 1984: Ord. 1861 ~ I (part), 1971).
18.06.040 Prohibited ncts. It is unlawful for any person to do any of
the following:
(a) Construct, alter, repair Or replace an individual sewage disposal
system or a component element thereof, which system is subject to the pro-
visions of this chapter, without first obtaining a permit from the health of-
fIcer in accordance with the provisions of this chap-ter and regulations is-
. sued hereunder. .. .
(b) Construct, rebuild, use, occupy or maintain any residence, place
of business or other structure where persons reside, congregate or are em-
ployed, which is not provided with a means of disposal of sewage by con-
nection to a public sewer system or an individual sewage disposal system,
without fIrst obtaining approval and/or a permit from the health officer.
(c) Construct, use, or maintain any privy, cesspool, septic tank, sewage
treatment works, chemical toilet, composting toilet, sewer pipes or conduits,
or other pipes or conduits for the treatment or discharge of sewage, impure
water or any other matter or substance which is offensive or dangerous to
health, in such a manner as to overflow onto public or private land or af-
fect any river, stream, creek, spring, lake, pond, reservoir, swamp, ocean,
bay, water supply or wat~r2Yilim.
(d) Install-(wplace a chemical toilet in or upon any property for any
purpose other than temporary use in connection with the construction of
a building or other structure during the period of such construction, without
fIrst obtaining a permit. fOrd. 2842 ~ 3, 1984~ Ord. 1861 ~ 1 (part). 1971).
(Marin County 2-88) 272.2
.
: ~
INDIVIDUAL SEWAGE DISPOSAL SYSTEMS 18.06.050-18.06.080
18.06.050 Connection to public sewer system and alternatives. Sewage
disposal shall be by means of a connection to a public sewer system if the
nearest sewer is within four hundred lineal feet of the parcel in which the
structure generating the sewage is to be constructed. This requirement may
be waived by the health officer if he fmds connection to a public sewer is
legally or physically impossible. If the health officer determines that
connection to a public sewer is unfeasible, an application may be med for a
permit for an alternative method of sewage disposal, utilizing an individual
sewage disposal system. (Ord. 1861 ~ I (part), 1971).
18.06.055 Building permit approval. No building permit, as required
by Marin County Ordinance 1189 (Chapter 19.04 of this code) and amend-
ments thereto shall be issued for any building which is not to be connected
to an approved public sanitary sewer, without the approval of the health
officer. (Ord. 284294,1984).
18.06.060 Regulatiops. The health officer is authorized to issue
regulations, providing guidelines and criteria to carry out the purposes of this
chapter. Such regulations shall be approved by the board of supervisors prior
to their effectiveness. The health officer is authorized to waive any particular
requirement imposed by such regulations if he determines that the general
purposes of this chapter will be achieved by such waiver. (Ord. 1861 S I
. (part), 1971).
.'
18.06.066 Permit required. Every person shall obtain a permit as
provided for by this chapter to repair, alter, relocate, install or construct an
individual sewage disposal system unless connection to a sanitary sewer is
required. (Ord. 284296, 1984).
, ,
18.06.070 Application and fees. All applic~tions for individual sewage
disposal system permits or requests for chemical toilet installations shall be
submitted in writing to the Marin County h.,.dlth and human services depart-
ment, division of environmental health services, on a form supplied by the
health officer. The application shall be accompanied by fees as specified in
the current resolution of the board of supervisors designating fees for
environmental health services. Additional fees related to monitoring of
modified, experimental or alternative systems shall be requested on an an-
nual basis, the cost of which shall be specified by Resolution of the board
of supervisors. (Ord. 2842 S 7, 1984: Ord. 2364 S I, 1978: Ord. 2352 S I,
1978: Ord. 1861 S I (part), 1971).
18.06.080 Health officer review. If, after investigation, the health
officer determines that the construction of the proposed facility is in
accordance with the terms of this chapter and any regulations issued
.....! pursuant thereto, and will not be injurious. to the public health and welfare,
he shall approve or conditionally approve'the application for an individual
272-3 (Marin County 3-86)
.
-. ,
18.06.082-18.06.100 SEWERS
se wage disposal system. Such approval may be made subject to such
conditions as the health officer deems necessary to insure compliance with
this chapter, and any regulations issued pursuant thereto. Any such approval
shall become null and void under the following circumstances:
A. The work authorized has not been commenced within one year
after approval, unless an extension of an additional one year has been
gran ted by the health officer;
B. Construction of the approved system is commenced but
subsequently abandoned for a continuous period of ninety days;
! c. Construction of the approved system is not proceeding in
accordance with the terms of approval. (Ord. 186 I ~ I (part), 1971).
18.06.082 Permits-Nontransferable. Any permits issued hereunder may
not be transferred from person to person, or location to location. (Ord. 2842
~ 8, 1984).
18.06.084 Permits-Revocation. The health officer may revoke any per-
mit issued hereunder if he determines that the permittee is acting in contra-
vention of the provisions of this chapter or the conditions of the permit.
(Ord. 2842 ~ 9, 1984).
.'
18.06.090 Certificate of inspection. If the individual sewage disposal
system is completed in accordance with the terms of the health officer's
approval, a certificate of inspection shall be issued by the health officer
which certificate shall be effective for a period of two years. The health
officer may revoke any certificate issued hereunder if he determines that the
individual sewage disposal system does not comply with the provisions of
this chapter, the regulations issued hereunder, or the conditions of the
" certificate. (Ord. 1861 ~ I (part), 1971). /
.
18.06.100 Biennial inspection and renew:J!. Every individual disposal
system constructed pursuant to this chapter shall be subject to a biennial
inspection to assure their continued proper functioning and for the purpose
.-"' - .' of renewing the certificate of inspection. The health officer shall renew a
certificate of inspection for a two year period when the following conditions
have been met:
A. A report of inspection of the individual disposal system by an
authorized inspector indicates that the system is operating in a satisfactory
manner;
B. Proof of a .septic tank pumping by a licensed septic tank pumper is
submitted, when such pumping is required by the report of the inspector;
C. Proof of repairs or alterations to an individual sewage disposal
system is submitted, when such repairs have been required by the report of
the inspector;
D. A deposit of renewal fee as established by resolution of the board of ~
.
(Marin County 3.86) 272-4
. - "
INDlVIDUAL SEWAGE DlSPOSAL SYSTEMS 18.06.1 10-18.06.140
supervisors is made with the county health department. (Ord. 2370 ~ 9,
. 1978: Ord. 1861 ~ I (part), 1971).
18.06.110 Recordation and transfer of certificate. The certificate of
inspection shall be recorded by the health officer with the county recorder,
identifying the property by assessor's parcel numbers. The certificate of
inspection is transferable to a subsequent grantee or transferee of the
property, effective for the balance of the two year period. (Ord. 1861 ~ I
(part), 1971).
18.06.120 Defective systems. Following the biennial inspection covered
above, if an individual sewage disposal system is found to be defective, the
prior certificate of inspection may be extended for a period not to exceed
six months beyond its normal expiration date; provided that corrective
measures as recominended by the inspector are being undertaken. (Ord.
1861 ~ I (part), 1971).
18.06.125 Abandoned sewage disposal facilities. Every cesspool. septic
tank, or privy which has been abandoned, or has otherwise been discontin-
ued from further use, or to which no waste or soil pipe from plumbing fix-
ture(s) is connected, shall have the sewage removed therefrom and be com-
pletely filled with a material approved by the health officer. (Ord. 2842
~ 10,1984).
18.06.130 Enforcement. It shall be the duty of the county health
officer or his duly authorized representative to enforce the provisions of this
chapter and the regulations issued thereunder. He may enter any premises at
any reasonable hour, with the owner's consent, to inspect the individual
" sewage disposal system to determine if it is functjo'ning satisfactorily. Should
for any reason the owner's consent not be obtained, the health officer shall
first obtain an inspection warrant pursuant to applicable law. (Ord. 1861 ~ I
(part), 1971).
18.06.140 Appeals. In the event that any applicant or permittee (here-
inafter called appellant) is for any reason dissatisfied with the actions of the
health officer by reason of failure to grant a permit, revocation of a permit,
or imposition of any conditions relating to said permit, said appellant shall
have the right to request a hearing before a board of appeals consisting of:
the health and human services director, the planning director and the public
works director. Appeals shall be addressed to the appellate body, in writing,
and shall state the. basis of the appeal. Appeals shall be filed in the office of
health and human services not later than ten days following the date of the
action from which the appeal is taken. Appeals shaH be accompanied by the
filing fee as specified in the current resolution of the board of supervisors
estaulishing fees for environmental health s"",ices.
272-5 (Marin County 3-86)
-. ...
18.06.150-18.06.160 SEWERS
The appeals board shall conduct a hearing within fifteen working days
from receipt of request. The action from which the appeal is taken may be
reversed or modified only by the affirmative vote of a majority of the ap-
peals board. The appeals board shall render a decision, in writing, within five
days. Actions or appellate determinations of the appeahboard may be ap-
pealed to the board of supervisors within ten days of the decision of the
appeals board. Said appeal shall be accompanied by a filing fee as specified in
the current board of supervisors' resolution establishing fees for environ-
mental health services. The board of supervisors shall determine an appeal
not later than the fourth regular m~eting following the date on which the
appeal was filed. The action or appellate determination, from which an ap-
peal is taken, may be reversed or modified only upon an affirmative vote of
a Il1ajority of the authorized membership of the board of supervisors. All
rights of appeal are exhausted when the proceedings set forth herein have
been consumated. (Ord. 2842 ~ II, 1985: Ord. 1861 ~ I (part), 1971).
18.06.150 Penalty for violations. Any person violating any of the pro-
visions of this chapter is guilty of a misdemeanor and, upon conviction
thereof, shall be punished by a fine of not morc than five hundred dollars.
or by impriso.nment in the county jail for not more than six months. or by
both such fine and imprisonment. Such person is guilty of a separate offense
for each and every day during any portion of which a violation of this chap-
ter is committed, or permitted by such person. (Ord. 2842 ~ 12, 1985:
Ord. 1861 ~ I (part), 1971).
18.06.160 Severability. If any section, subsection, subdivision, sentence,
clause or phrase of this chapter is, for any reason, held to be illegal or uncon-
stitutional, such decision shall not affect the validity 'of the remaining por-
, lions of this chapter. The board of supervisors declares that they would have
passed this chapter and each section, subsection,' subdivision, sentence,
clause or phrase thereof, irrespective of the fact that anyone or more
sections, subsections, subdivisions, sentences, clauses or phrases are de-
clared illegal or unconstitutional. (Ord. 2842 ~ 13, 1985).
Chapter 18.08
SEWER CONNECTIONS-CHARGES
Sections:
18.08.0 I 0 Connection charge established.
18.08.020 Permit for fixtures.
.
(Marin County 3-86) 272-6
)
.
Regulations for Individual Sewage Disposal
Systems adopted pursuant to Section 18.06.060
of the Marin County Code.
REGUUnONS FOR DE:SIGN. CONSTRucnON AND
REPAIR OF I:lDIVIDUAl. SEWAGE DISPOSAl.
SYSTfrlS
TABLE OF CONTE:lTS
Seccion Pal<e ~llQber
100 permic Application and Procedures .. .. . . . . . . . . . . I
200 Definitions .. .. .. .. .. .. .. .. .. . . . . . . .. .. .. .. .. . . . 2
300 General Prov1sions. .. .. .. .. . . . .. .. .. .. .. .. .. .. . . . . 6
400 Sice Suicab1licy Cr1ceria . .. .. .. .. .. .. .. .. .. .. .. .. .. . . 8
500 S1ce Evalllacion Requir...",ncs. .. .. .. .. .. .. .. .. .. .. .. .. .. .. LCJ
600 Design Criceria . . . . .. .. .. ... .. .. .. .. .. .. .. .. .. .. . .13
700 Inscal1acion and Inspeccion . .. .. .. .. .. .. ..". .. .. .. .. .. . 22
800 Alcernacive Syscems . (SEE SEPARATE PACKAGE)
.. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .
900 Waiver of Regulacions . . . . . . .. .. .. .. .. .. .. .. .. . .. .. 23
Fig. 1 Typical Sepcic Tank Decails . . . . . ~ . . . . . . . . . 25
Fig. 2 WascewaCer Loading Criceria . .. .. .. .. .. .. .. .. .. .. .. .. . . 26
Fig. 3 Typical Dra1nf1eld Trench Decails . . . . . . . . . . . . 27
Fig. 4 Ser1al D1scr1buC1on Decails . . . . . . . . .. .. .. .. .. .. .. 28
F1g. 5 Elevaced Cover Fill Decails . . .. .. .. .. .. .. .. .. .. .. .. .. . 29
Fig. 6 Eff1uenc Pump and Sump Decails. . . . . .. .. .. .. .. .. .. .. .. 30.
Fig. 7 Typical Incercep c Trench Decails. . . . . . . . . . . . . 31
Fig. 8 Typical Mound Syscem Decails (end View) .. .. .. .. .. .. .. .. .. 32
Fig. 9 Typical Inspeccion Well . . . . . . . . . . .. .. .. .. .. .. . 33
,
REGUU.IIONS FOR DESIGN, CONSTkUCIION .'...~D
REPAIR OF I~DIVIDliAL SEliAGE DISPOSAL
S't'ST::!S
PURSUANT TO MARIN COUNTY CODE CHAPTER 18.06
100 PER-'1IT APPLICAIION A..'1D PROCEDURES
101 Applicacion fa r an I~dividual Sewage Disposal Per=ic shall oe made
on a form supplied by Che Healch Officer accompanied by che ap-
propriace fee.
10Z All info t'llla cion required on che form must be supplied or che ap-
plicacion will be deemed incomplece and recurned Co che applicanc.
103 Three copies of a decailed Ploc Plan shall accompany each applica-
cion for a permic, drawn Co a scale of tlOC less chan 1 inch equals
ZO feee. Plans shall be a minimum of 8 i/z" x 11" in si"e and no c
greacer Chan Z4" x 36" in ~~"e. Plans shall conCain Che following:
A. LocaCion lllap indicacitlg 10caCion of parcal. wi ch respecc Co com-
municy and nearesc public road.
B. Parcel boundary and dimensions.
.
C. Owner's name and address of dwelling or structure, Assessor's
Parcal. Number, norch arrow and plan scale.
D. Locacion of all wells (boch onsite and in general vicinicy),
springs, wacercourses and wacerbodies, marsh areas, drainage
di cches, channels, cucs, embankmencs, nacural bluffs or unsCable
land forms on che properey or wiChin iOO hec of any porrion of
the proposed syscem or reserve area.
E. LocaCion of ex.iscing and/or proposed scruccures, S\rt.lIllIIing pools,
retaining walls, driveways. paved areas, water lines. unde rgr ound
u cili cies and easments on che siu atld within Z5 feec of the
proposed syscem off sice.
F. COtlcours, andlor spoc elevations, excepc Chac parcels where che
aver age slope is 5% or less IllaY indicace only che direccion and
percencage of slope. The direcCion and percentage of slope of
che drainfield area shall be shown for all plans.
G. Locacion of any exiscing sewage disposal syscem( s) on the pro-
percy.
Ii. Layouc (including dimensions) of proposed syscem.
I. Typical crench section and 8QY other essencial cons cruccion de-
cails, such as pumps, intercept drains. etc.
J. Location of iadi vidual soil percolacion Cest holes and so 11
profile holes.
-1-
,
K. Name and signature of Regis cered Civil Engi nee r: or Reg:s:ero:d
Saniearian responsible for design.
104 5011 pe rc.ola~~on test resulcs~ soil profile logs and/ or resu.:.:3 of
so 11 tex~u:al analys19 s"all acc.ompany each applic.acion, on fa r:ns
supplied or approved by the Healeh Officer.
IOS Each appl1caeion shall be accompanied by ehe calculaeions used co
determine sizing of ehe sep c:1c eank and abso '1> cion area and any
ocher special design features.
106 Accepeance of an applicaeion for a pemie as complete does noe
guarantee thae a peJ:lll1e will be issued. Issuance of a pe rni e does
not ensure that a syseem will operaee saeisfaceorily.
107 Upon issuance of a sepeic sys t em peJ:lll1e and building pernit (if
requeseed) wo tk lllaY cc:mc:ence on construceion of the appproved
system. The septic tank and dralnfield/ absorption area may noe be
covered untU a final inspect ion is perfo med by ehe Healeh
Officer. A 1Il1nlmUlll of 24 hour advance notice is required to arrange
for final inspections by ehe Healeh OHicer.
10l! A copy of the building plans, including the approved sewage disposal
system, shall be available at the job site during the system instal-
lation and until the syseem is approved by ehe Health Officer.
200 DEFINITIONS
201 AbsoJ:ll cion Area: The effective absorption area shall include only
the two sidewall areas below the bottom cf the drainfield pipe.
202 Aleernaeive Svs tem: Any individual sys tem that does noe incl"de a
s tanclard septic taalr. for trea. tRn t t or does not incl"de standard
leaching trenches for effl"ent disposal, which has been demonstrated
to function in such a manner as to protect water q ualiey and
preclude health hazards and nuisance condieions.
203 Bedrock: Solid ro a, which may have fractures, thae lies beneath
so11s and other unconsolidated maeerial. Bedrock may be exposed at
the surface or have an overburden "p co several hundred feee en l.ck.
204 Bed roOlll: Any roem designated by applicant as a "bedrocm"; other
roClllsy s uc11 as s ewi ng rooms, dens, offices, s eudios . 1 of e s . game
rocms I etc. , may also be considered as bed rooms. Rooms having one
or 1lICre of the following features lIlay noe be cons ider ed by ehe
Healeh Officer to conseieute a bedroOlll:
A. A large, arched doorway w1thoue a door which opens onto the en-
tryway or a main activiey area.
B. Use of a half wall or railing along at leas t one side of the
ro all.
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C. A conversation pit which interrupt. the floor area.
Nothwithstanding the above provisions, the minimum number of
bedrooms for any dwelling shall be no less than the fo llowing:
Gross Floor Area No. of Bedrooms
0-1400 5.F. 1
1401-1900 5.F. 2
1901-2800 5.F. 3
Over 2800 5.F. 4
205 Buildin!1;: A structure including decks and steps, whether covered or
uncovered, breezeways, covered pa tics, carpotts and similar struc-
tures.
206 Clay: As a soil separate, the mineral soil particles less than
0.002 millimeter in diameter. As a soil textural' class. soil 1IIa-
t en al that is 40 pe rcent or more clay, less than 45 percent: sand,
and less than 40 percent silt.
207 Cut or Embankment: Any altered area of land surface having a
distinctly greater slope than the adj acent natural ground surface,
over 24 inches in vettical height, and any part of which is . lower in
elevation than the ground surface at the neares t poi nt of the
iOOi vidual sewage dis posal S'JS tem. Cuts supported by retaining
walls or similar structures shall be i nc:luded within this
defini tion.
208 Dosinp; Tanks - Tanks which colle ct treated sewage for a period of
time and then, periodically, discharge it into an absorpt ion area
by means of an automatic siphon so that the effluent distribution is
equal throughout t:he entire leaching area.
209 Downslope Property Line: A property line of the subj ect prope rty
where the ground on the adjacent property slopes downward from that
property line.
210 Drainfield: 5ys tem of rock-filled trenches or bed (s) that dis-
tribute treated sewage effluent for absorption into the soil (also
-Leachfield" , "Soil Absorption 5ys t.em").
211 Dual Drainfield: An effluent disposal system consisting of two com-
plete standard drainfields connected by an accessible diversion
valve and intended for alternating use on an annual or semiannual
basis.
212 Effective Drainfield Depth: The depth of drainrock below the bot tom
of the drainfield pipe.
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213 Eoh~eral Waeercourse: A seasoaal scre~ chac flo~s for an ~~t~~ded
period during aod follo~.c..g a rai.n.:a.1~ period. Ephe.ro:...:!=a.l s C=ea;:;:s
are dry for a significanc portion of the year.
214 Groundo;;ater: Any subsurface body of ;;ater I..hicb. is benefic1 ally
used or is usable. IC includes per~~ed wacer if such waCer is used
or usable, or is hydraulically conCinuous ~ch used or usable waCer.
215 RardDan: A hardened or cem.ented soU horizon or layer. The soU
macerial may be sandy or uayey and Illay be ceunted by iron oxide,
ailica, calcium carbonate, or ocher subst:ances.
216 Health Officer: The Marin County Health Off~er or l1is/her aut:har-
i:ed representacives.
217 Impermeable Laver: A. aoil or geologic focation which =y conta..1.n
wter but is incapable of transllll.t:ting significant quantities. Por
e:ca:ple, clay, hardpan and soUd bedrock belong in tl1is category.
218 Inter::::l.ttent >latercourse: Any observable vatercourse that .flow
only in direct response to prec1pitacion. It receives nO water from
springs and nO long-continued supply frCll Illeltiag SnOW or other sur-
face source.
219 Leac:hfie1d: See Drainfield.
220 Mottl.iOS\ , SoU: Irregularly Illarked ~th spots of different colors
that vary in llUmber and size. M.ottling in soils usually indicates
poor aeratiou and lac~ of dra..1.nage.
221 Mound: An individual sewage disposal system. that utilizes a per-
meable fill material and by dispersion or unifoCl application of
wastewater makes ID:lre effective use of absorption capabilities in
areas contaJ.a.:l.cg high groundwater levels or soils of lim;!. t ed
per:aablllty or deptl1. A Illound contains the follo~cg parts; ( 1)
the mounc1 body fill ma terial; (2) the dis tribu tion bed; (3) the
c1istribution =ifold and laterals; anc1 (I,) the topsoil cover.
222 Perched >later: A subsurface body of water separatec1 froc the main
groundwat:er body by a relatively :l.mper:::eable stratU.III above the main
groundwater body.
223 Percolation Test:: The percolation test procedure autl:ori:ed by
these regulations.
224 Perennial >latercourse: Any stretch of a st:re~ that C~n be expect:ed
to flow coot:inuously or seasonally. Perennial fJatercourses are
generally fed in part: by springs.
225 Public Ent:i q: Shall lIlean a local agency, as defined in the Stat e
of California Government Cc~e, Seccion 53090, et seq., which is ~
powered to plan, design, fi~ce, construct, operate, maintain, and
to abandon, if necessary, any se....age system. or the expansion of arrj
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sewage system and se""'age treatment facilities servi"lS a land devel-
opment. In addition, the enti ty shall be empowered to provide per-
mits and to have supervision over the location, design, finac.cing: ,
construction, operation. and maintenance of any facilities necessary
for the disposal of waste pumped from indiVidual sewage disposal
systems and to conduct any monitoring or survelllance programs re-
quired for 'Wa ter quality control purposes ( unles s there is an ex-
isting public entity perfom.1ng these tasks).
226 Sand: Individual rock or mineral fragments in so ils having diam-
eters rang1 ng from 0.05 to 2.0 millimeters. Most sand grains con-
sist of quartz , but t hey may be of any min e r al composition. The
textural class name of any so 11 that contains 85 percent or more
sand and not more than 1U percent clay.
227 Saturated 5011: The condition of soil when all available pore space
is occupied by water and the so11 is unable to accept addi tional
moisture. In very fine te~ured soils a free water surface may not
be apparent.
228 Seep"!!e Bed: A type of abso rption syst... which uses a very wide
trench partially fll1ed with gravel or crushed stone. Piping dis-
tributes the treated sewage evenly throughout the entire bed so that
it may seep into the earth. The seepage bed is covered with sol1 to
prevent sewage from reaching the ground surface. (Also Abso rption
Bed.)
229 Septic Tank: A water-tight, covered receptable designed and con-
structed to receive the discharge of sewage frail a bullding sewer,
s epar aCe solids from the li quid, diges t organic matter and store
diges t ed solids through a period of detention, and allow the cla-
rified liquids to discharge for final disposal.
230 Serial Distribution: An arrangement of an absorption area in which
the lines are connected consecutively to receive the flow of sewage
one after another. It is most useful for hll1-side locations.
231 Setback: The minimum ho ruo ntal distance from any point along the
Outs ide edge of a sepeic tank or the edge of a drainfield trench,
mound, etc., to any point on the described site feature.
232 Silt: Individual mineral particles in a so11 that range in diameter
from the upper limit of clay (0.002 millimeter) to the lower limit
of very fine sand (0.05 millimeter). 5011 of the silt textural
class is 80 percent or more silt and less than 12 percent clay.
233 5011: The unconsolidated material on the surface of the earth that
exhibi ts properties and characteristics that are a produc t of the
combined factors of paren t material, climate, living organisms ,
topography, and time.
234 Soil Absorption System: See Drainfield.
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235 Soil Deoth: The cOlllbined thickness of adjacent soil layers ehae are
suitable for ef fluent filtration. Soil depth is measured vertically
to bedrock, hardpan, or an impeOleable soil layer.
236 Soil Horizon or Layer: A layer of soil differing frcm adjacent
(underlying or overlying) layers in some property or characl:er-
istic. Differences include, but are noe limited to, color, texture,
pli, structure, and porosity.
237 Soil Texture: The relative proportions of sand, silt, and clay as
defined by the classes of the soil textural triangle (U .5. Oepart-
lIlent of Agriculture.). The basic textural classes in order of in-
creasi ng proportion of fine particles are sand, 10ay sand, sandy
loam, loam, silt loan, sUe, sandy clay loam, clay 10""', silty clay
loam, sandy clay, silty clay and clay. Textural classes lIlay be
1Il0dified when coarse fragm.ents are present in sufficient number,
18., gravelly sandy loam, cobbly clay, etc.
238 Unstable Landform: An area wllich shows evidence of mass downslope
movement. such as debris flow, landslides, rockfills, and hummocky
hUlslopes wi th undrained depressions upslope. Unstable landfo rms
lIlay exhibit slip surfaces roughly parallel to the hillside; land-
slide scars and curving debris ridges; fences, trees, and telephone
poles which appear tilt ed; or tree trunks which bend uniformly as
they enter the ground. Active pond dunes are unstable land forms.
239 Watercourse: A definite open channel with bed and banks within
which water flows either perennially, ephemerally or intermittently
includi ng overflow channels contiguous to the main channel. A
watercourse shall include both natural and man-made channels.
300 GENERAL PROVISIONS
301 New Sys t ems on Newly Created Lo to: Individual sewage disposal
systems serving new improvements on lots created subsequent to the
approval of these regulations, revisions or amendmen ts thereto,
shall cOlllply in all respects to the regulations in force at the time
of the approval of the Tentative Map approving such lot without the
necessity of a variance from the elements of such regulations.
302 New Sys rems on Exisrilll!' Lots: Individual sewage disposal systems
serving new improvements on lacs created prior to ap proval of these
regulations, revis 10ns or amendments thereto shall comply in all
res pects to the current regulations. The Health Officer lIlaY cor,-
sider variances from these regulations as provided herein.
303 Modification to Existi~ Systems: Where an existing sewage disposal
system is proposed to be expanded, replaced or relocared because of
proposed major changes to an existing scruc1:ure se rved by an
individual sewage disposal sys tan, such as addition of bed roOllls fo r
a res idenc e or changes in use or expansion of a nonres iden tial
structure, the following criteria shall apply:
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(a) If the property currently is within 400 feet of a public se~""er
main and it is physically and legally pass ible to connect to
such main as determined by the Health Officer, no expansion of
the enstiog sewage dis pas al sys tem will be allowed and con-
nection to a public sewer shall be required.
(b) If the property does not meet the above criteria requiring con-
nection to a public sewer, the sewage disposal system may be en-
larged or relocat ed in accordance with these regulations to
accOlllodate the increase in sewage effluent. If it is determined
by tlie Health Officer that the ex1s tiog drainfield is not
functioning properly, its hall also be repaired or replaced as
required by the Health Officer. In the event said system does
not utilize a septic tank which satisfies current regulations, a
new septic tank cOlllplying with these regula tions shall be in-
stalled.
(c) If the existing system' s design included a specified reserve
area, then this reserve' area shall not be used in any way that
would preclude its intended use unless a substitute area is
provided or it can be clearly delllOnstrated that the systelll was
built or can be lllodifiea so as to not require a reserve area.
304 Repair of Ex1sti!ll: Systellls: Where it is necessary to repair or make
1Il0difications to an existing system, every effort shall be made to
0. Olllply with the curren't regulations. If repair of the system is
required by the Health Officer and the property currently is wi thin
400 feet of a public sewer main and it is physically and legally
possible to connect to such main as deter1lli.ned by the Health
Off icer, then connection to a public sewer main shall be required.
If it is found to be 1JIlpractical or 1JIlpossible as determined by the
Health Of flcer to repair the systelll usicg a standard drainfield as
described in these regulations and connection to a sewer main is not
possible, the Health Officer lllay consider an alternative design.
305 Land Divis ions and Subdivisions: Eve ry tentative map for which
1ndividual sewage disposal sys tems are proposed shall include
sufficient information to demonstrate ccnfo emance wi th these
regulations and 0. cmpl1anc e with Marin County Code Section
20.24.060(0.). This shall include:
A. Soil profiles and percolation tests as specified in Section 501
and 502.
B. Sch...a tic layouts 1ncluding drainfield location and building
envelop to verify that a drainfield of sufficient size can be
installed to ace c:mmo da tel the potential sewage loading frOlll the
propos ed lot without need of a variance frOlll these regulations.
Fo r proposed residential locs, the design shall be based on a 3
bedrocm residence.
306 Location of Systems: An individual sewage disposal systelll serving a
buildiog or buildiogs shall be located on the sallie building sice,
lot or parcel as the building(s). Where an existing parcel is found
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Co be unsuic.able co acccn:u:c.odate an individual se~Jage disposal sy-
stem, che syscem may be locaced 00 anocher loc or parcel wichin a
noc.revoc.able easement: specifically designaced for such sewage dis-
posal syscem.
307 Comcon Sys tems: Coeman individual systems serving more than one lac
or parcel , regardless of o-wnersh1p, shall be prohib1c ed Wlless
operaced and maincained under che auchoricy of a publ1c encicy.
400 SITE SUITABILITY CRITERIA
401 Se cbacks
Minimum horizoncal discances beeween che sepcic cank and drainfield
syscem and various physical sice feacures shall be as follow:
Se cback co Se cback co
Edge of
Sice Feacure SeDcic Tank Drainfield
Building. ................ ............ .... .............. .... ...................... 5 feec 10 feec
Adjoining Propercy Line (1).................. 5 fee C 5 fee c
Downslope Property Line (1).................. 10 fee c 25 (5)
Wells (domestic or non-domestic)............. 50 feet 100 feec
Perennial Watercourse (2).................... 50 feec 100 feec
Ephemeral Watercourse (2).................... 50 feec 75 feec
or Seasonal We ~and
IncenniccenC Wacercourse (2)................. 50 feec 5U teec
Nacural Lake or Wacer Supply Reservoir (3)... 100 feec 2UO feec
Ocean, Bay or Tidal Estuary (4).............. 50 feec lUU feec
Edge of Drainfield Pipe...................... 5 feec -
Cuc, Embankmenc or Nacural Bluff............. 10 feec 4h (6)
Uns table Land Fe rm... .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 4 .... .. .. .. .. .... 50 feec 50 feec
Swimming Pool........................................... 10 fee C 25 feec
Domestic Wa:er Line.......................... 10 feet 10 fee:
Driveway or Paved Surface.................... 5 feec 5 feec
(1 ) wnere che property line excends inco a public roadway easemenc che
setback .hall be a>easured from che near edge or the easemenc:..
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(2 ) Discances shall be measured rrom che cop edge or che bank.
(3) Discances shall be measured rrom che high-wacer line.
(4) DisCances shall be measured rrom che mean higher-high-wacer line.
(5) Secback discance shall be 50 reec if che propercy line is one where chere
is a reasonable chance chac a cuC bank could be excavaced for house .or
road construction.
(6 ) DisCance in feec equals four cime s che verCical heighc of che cuc,
embankmenc or bluff 0 r 50 feee, whichever is less, buc in no case les s
than 25 feet or lIlOre than 100 feec. Distances shall be measured from che
cop edge of the cut, embankmenc or bluff. Where an impe r.oeable layer in-
tersects a cut, and nacural seepage is evident, the setback shall be 100
feec frC1ll che cut, unless it can be demonstraced thac ocher sice factors
(e.g., soil depth) adequately p:otects againsc laceral seepage or un-
treated effluenc.
.
402 Dell th to Groundwa ter
Min1mWll dep ch to che anticipaced highest seasonal level of groundwater
below the boccC1ll of the drainfield trench shall be as follows:
Min1mum Depch
Persolation Rate Soil Texture co ~easonallY
(min/inch) (% Silc + Clay) 1 H1~h raundYoScer (Ec.)
Slower than 5 or More than 15 32
1 to 5 and 10 to 15 10
1 to 5 and less than lO 20
Faster than 1 system prohibited
403 Ground Slope
A. The ground slope in the drainrield area shall noC exceed 20% wichouc
special engineering design.
B. Where the proposed drainheld sice exceeds 20%, a geological
engineering report shall be required. The report, prepared by a
regiscered civil engineer or certified engineering geologist, shall
delllOnscrace chac che use or a soil absorpcion syscem will noc creaCe
.. Soil of chis Cext:ure or finer IIlUSC exisc ror a minimum of Chree (3) con-
cillUous reec between che boccom of che drainfield creach and the waCer
2. cable.
A minimum of 2 feet may be granted only as a variance of for certain a1-
Ceruacive sysCems.
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a public healch hazard or oche"'olise jeopardize che proposed bu~lding
siee or contiguous properties.
C. For slopes greater chan 404, special design techniques (e..g.. J pres-
sure discribucion) shall be required; conventional. le achi ng crench
designs shall no~ be pe~~cced.
404 Soil Deoth
A. M1ni:num depch of soil below che boccolll of che drainfield crench
shall be three (3) feec.
B. Soil dep eh is measured vertically to che poine where bed. rock,
fractured or solid t hardpan or an 1mpe rme able soil layer is
eucoun cered.
C. Soil depth and suitability shall be detemined in accordance wi th
inspection procedures outlia"d in Section 500.
405 Percolation Rate
A. The percolation raCe of soils in the disposal area, including
reserve area, shall not be slower than 1 inch per 120 lll1nutes (120
MPI).
B. Where percolation raCes are faster Chan 1 inch per 5 minutes (5
MPI). then addi tional groundwter separation dis ranees lllay be
required as outlined in Subsection 402.
C. Percolation rates shall be dete rmined in accordance wUh tes cing
procedures outlined in Section 503.
500 SITE EVALUATION REOUIREl1ENTS
501 General
A. Site evaluations shall be perfo ODed on all locs for which se"..lage
disposal improvements are proposed in order to decermine cOlllp~ance
wiCh the sice suitabilicy criceria specified in Seccion 400. and as
a basis for syscem design.
B. Site evaluations shall be perfo"",ed by 0 r under the supervision or
one of the following:
1. Registered Civil Engineer
2. Registered Geologisc
3. Certified Engineering Geologisc
4. Registered Sanicarian
5. Certified Professional Soil Sciencist
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C. Site inspections shall also be condUc. t ed by the Health Officer to
verify ccmpl1ance wi. th any or all of the provisions of these
regulations.
SOZ So 11 Prof ile Ins oecr:ion
A. SoU condi tions shall be evaluated by direct inspection of the sail
profile, using backhoe excavations. hand-augering or core sampling.
B. If a backhoe is used, a minimum of one (I) excavation in each of the
primary and reserve areas shall be required. If an auger or coring
device is used, a minimWll of two (Z) borings in each of the primary
and reserve area shall be required.
C. Far land divisions and subcU...,is1ons I a minimWll of one (I) backho e
excavation or two (Z) auge r ed test borings (or corings) shall be
required fa r each of the first four (4) lots. For proj ects having
over four (4) lots, and wh~re the Health Officer finds the lots are
generally uniform in configuration, terrain and soil character-
istics, a fewer number of soU prof Ues may be allowed. In all
cases, a sufficient nWllber of soU profile excavat~ns shall be made
to identify suitable drainfield locations and reserve areas an each
proposed parcel.
D. The sail profile shall be inspected to a depth of at least three (3)
feet below the . bot tcm of tbe proposed dis posal system. The
following observations shall be made and recorded:
1. Thickness, depth and texture of soU layers encountered.
Z. Depth to bedrock, hardpan or other impermeable layer.
3. Depth to groundwater.
4. Evidence of soU mottling.
5. Other conditions affecting the potential use of the soU for
sewage disposal, including , but not limited to, evidence of
roots. fissures, dampness, structure and stoniness.
503 Percolation Testin~
A. Percola tion tea ts are to be carried out (in soils in their n'ative
state) at the proposed depth of the soU absorption field and at
lesser depths as may be required by soU changes. Percolation tests
may be conducted at the bottom of backhoe or other excavation holes
where deeper testing is required by the Health Officer. Additional
percolation testing or text:ural analysis of deeper sail zones may be
required by the Health Officer to determine if underlying sails have
adequate pe.rmeability.
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B. Individual cescs are co be run in 6" co 12" diaI:lecer holes dug or
bored us i ::g hand co 0 Is. It po..-er based cools are uS ed re!:.ove any
smeared soil surfaces frem che sides of che hole.
c. Remove loose ma=.erial frcm ehe botccm of ehe hole aod add 2 inches
of coarse sand or fine gravel co proeecc ehe boccom from scouring.
D. If soils t.end Co collapse, place a perforaced pipe in ehe hole and
carefully pack gravel a round ie bet:":Jeen cne pipe and the hole
wall. Where gravel pac.lc is needed , ehe percolaeion race shall be
adjuseed for ehe waCer displacemenc aeeibrucable eo ehe gravel ana
perforaeed pipe. The adjuscmene faceor shall be ccmpueed based upon
deeerminaUon of the actual percentage of void space in ehe gravel.
pack poreion of ehe eese hole.
E. Presoaking is required in all eeses. The wacer shall be carefully
placed wiehin ehe hole. Waeer mus e be added co ae lease 12" depeh
over ehe gravel and. lllaineained ae chis level fa r ae leas e 4 hour s
and. preferably overnighe. If elle soU is mown eo have a low
s hr ink.-swe 11 po eeneial (clay coneene 157- or less) Ces cing lllaY
proceed (Seceioo F) afeer ehe 4 hour presoak.
SoUs wieh higher shrink.-swell poeenUal are eo be ees ced ehe
following day huC wiehin 24 hours of presoaking as follows.
F. Fill ehe hole wieh clean waeer (00 ch~cal addieives) approximaeely
6" above ehe gr avel (or 8 .. above ehe boeecm of ehe hole). Wieh a
floae guage or seOlre fixed reference and eime piece d~te~ne the
eime for ehe wacer eo recede oae inch or deeermine elle drop of waeer
afeer an ineerval of 3u eo 60 minutes. Refill and repeat: ehe
process I over a 2-hour eo 4-llour period . uneU subsequene tests
indicaee a seabilized race has been obeaine<1 (i.e., two coasecutive
races are wichin aboue 10% of each oeller). The lasc wat.er level
drop is used eo calOllaee che percolaeioa raCe. Time lapse be~.een
tese iate rvals sllould be lIl1aimal (5-10 lII1nuees) . Tese res ulcs
should be reporeed ia units of IIl1nuces per incll.
G. Ae lease six percolaeion eesCs sllall be made in separaee eese holes
spaced over tile proposed drail1 field area. ,n leas e ehree of ene
eese holes snall be at ene boe Ccm deptn of ene proposed drain-
fi ald. The oeners lllaY be placed ac ineermediace depens. The
aver age of che six ces cs s nall be used for decermining cne
appropriace loading raCe from cne cable in Seccioa 603B.
H. For land di.visioas a 1Il1111::lum of thre e (3) percolacion test holes
shall be required for each of clle firsc four (4) lacs. For proj ecCs
Ilaving over four (4) lacs, and where che Healcll Officer finds che
lacs are generally unifo rm in soil characteristics I a fewe r number
of percolacioa tes ts may be allowed. In all cases, a suffic.ient
aUlllber of Cests shall be lllaae Co idencify sui cable dr aief ield
locacioas on each proposed parcel.
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504 Wet weather Tescin~
A. Wet weather de l:ermination of grouodYacer leveLs shall be required
except in areas dete=ined by the Health Officer to have aaequate
documencacion of gt'oundwacer conctitians.
B. Wet weather percolation testing may be required in areas deter=ined
by the Health Officer to have (1) clayey so lis (greater than 30~~
clay) with high shrink-swell potential or (2) peten C1 al soil
saturation problems. Text ur al analysis of so Us may be requi red by
the Health Officer to make c.ase-by-case determinations or ne eds for
we t weather tes ting.
C. The wet weather testing period shall be dete~ined annually by the
Healrh Officer on rhe basis of rainfall occurrence in dif ferenc
areas of the Coun ry as follows:
Be!!1nnin,,: On January 1s);' or afrer one-half (1/2) of rhe
seasonal normal precipiration has fallen. which-
ever occurs SOoner.
Endin!,: . On April 15th, or later in the event or unusually
heavy spring rainfall.
600 DESIGN CRITERIA
601 Sewall;e Flows
A. Sinll;le and Multiple Family Dwellinll;s. For design purposes, minimum
sewage flows frem residenC1al buildings shall be calculared based on
150 gallons per day per bearoom..
B. Orher Buildin!';s: Sewage flows for cClllllll!rcial es rabUs tunents and
other noa-residential buildings shall be es t1ma red in accordance
wirh rhe quantities Usred in Table 1. Orher sewage flow estimares
may be considered by rhe Healrh Officer if suppa reed by adequare
rechnical documentation.
C. Wa re r SaviI1l1; Devices: Reduc tions in design sewage flows may be
granted where certain water saving devices are incorporated per-
manently into the buildings being served.
1. Reductions of up to 30:: may be granted where either 2-quare air
drive or 3-liCer pressure flush toUers are installed in all
barhroans.
2. Flow reductions for other water saving devices may be con-
s idered by the Health Officer on a case- by-case basis or in
general as wa ter conservation technology develops.
3. All installations incorporaC1ng water saving devices shall
require design and final inspection by a regisrered civil
e ng1neer , and recordation of water use res trictions on the pro-
perry deed.
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)
TABLE 1
Quanriries of Sewage Flow
Gallo!lS per
Tvoe of Establlshoenc Person per daY
.
( unless otherwise nored)
Small dwelling and cottage wirh sea son al ocCJ.pancy......................................................... .100+
Hords wi rhou t priva re baths. .......... ...... ...... ...... .. e_......... .... .................... .... .... ........ ........ .... .... .. .. 50
Horels wirh privare baths (2 persons per room)........................................................... .. 60
Restaurants ( roilet and ki tchen wa s te per patron)............................... 10
Restaurants ( ki tchen wastes per meal se r:ved).. .. .. .... .... .. .. .. .. .. .. .. .. .... .. .. .... .. .. .. .... .... .. .. .. .. .. .. .. .. 5
Addi r io aal for bars and cocktail 10llnges. .... .................... ...... .............. ...... ........ .. ............ .... .. 2
Touris r camps or rrailer parks wirh cenrral ba thhause.. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 75
Tour isr courts or IIlObile home parks wirh individual barh units.................. 100
Re sort camps ( night and day) with limired plumbing......................................................... .. 50
\Jork or cons rruc rion camps (sem.i-peti:nanent)........................................................................ .. 50
Day camps (no meals served)......................... ............ ................ 15
Iiay schools wi rhout cafe cerias, gymnas.1.ums, or showers.......................... 15
.' Day schoo ls with cafeterias bur no gy1llllasiums or showers................ .... ... . 20
-
Day schools wi th cafeceri,as, gyms, and showe rs. . . .. . . .... ..".. .. . . . . . . . . . . .. . . . . . 25
Boarding schoo Is.. .. ..... ............... . . ...... ..........o... ......... ... . . .... . 100
. Day wo rke rs ar schools and offices ( per shifc).............. .o................... 15
Has pi r als ( per bed space)...................................................... .250+
Institutions other than hos pi rals ( per bed space)............................... ~25
Facrories ( gallons per per son per shift, exc.lus i ve of indus rrial wastes)....... . 35
Picnic parks ( railer wasc.es only) , (gallons per pic.nicker)..................... . 5
Picnic parks wirh barhhouses, 5 howers , and flush toilets........................ 10
Swimm1ng pools and bathhouses....................................................... . 10
Counrry clubs ( per residenc. member)....................................................... . 100
. -14-
,
County clubs (per non-resident member present).... ........ ............... ....... 25
ltotl:!ls (pli:r bed space).......................................................... 40
Motels with bath, toilet, and kitchen wastes.................................... 75
Drive-in theaters (per car space)............................................... 5
Movie theaters (per auditorium seat)............................................ 5
Airports (per passenger)..... .... .... ...... .... ...... ...... .......... ....... .... 5
Self-service laundries (gallons per wash, i.e., per customer)................... 50
Stores (per toilet room)........................................................ 400
Service Stations. (per vehicle served)........................................... 10
602 Septic Tank Desi~
A. ~. The required minimum septic tank size shall be as fo 110ws :
1. For single family dwellings:
Numbe r of Minimum Tank
Bedrooms Capacity, Gallons
4 or less 1200
5 or more 1500 plus 250 for each bedroom over 5
'2. For other building, the capacity shall be at least two times the
daily sewage flow and, in no case, less than 1200 gallons.
B. Compa rtCle nt s : The septic tanks shall be of two campa rtme nt con-
s truct io n. The first compartment shall be twice. the capacity of the
second and separated by a baffle. The arrangement of tank features
shall be as soown in Figure 1, unles s at he rwise ap pr oved by the
Health Officer.
C. Placement. Septic tanks should be ins tal led so that manho Ie
opening(s) are within twelve (12) inches of ground surface.
D. Construction Materials. The tank shall be watertight and shall be
constructed of reinforced concrete, standard weight reinforced
concrete block, fiberglass or other durable , non-corrodible syn-
thetic materials approved by the Health Officer. Metal or wooden
tanks shall not be permitted.
E. Structural Strenp;th. The tank shall be capable of withstanding
anticipated structural loads. The tank top must be capable of
support ing an eart h load of not less than 300 pounds per square foot
when maximum coverage does not exceed three (3) feet. The minimum
compres si ve strength of any concrete tank wall, top and cove rs , or
-15-
,
fl oor s hall be t:"." ncy-f i'le hundred (2 Saa) pounds pac square inch.
F. Bedding. Ihe cank shall be ins called level on a solid bed. Soil
around ehe eank shall be hard-compaceed or jeeced.
G. Access Risers. A riser shall exeeed frClll each manhole cover co the
surface of che ground co allow access for inspection and maintenance
of the cank. Ihe riser shall be of a size sufficienc for removal of
che manhole cover and shall be coc.scruct.ed of durable maeerials.
SepCic Canks in areas to be surfaced by concrete. asphalt or similar
paving shall have access riser(s) broughc to grade.
H. Buildi~ ConnecCions. All connections frem buildings co sepcic tank
shall be made in accordance wieh the 1llOst recenC edi cion of the
Uniform Plumbing Code which is incorporated by reference into ehe
Coun!:y's Building Ordinances.
I. Variances. Sepcic caoks . C which deviace frcm che above design.
cr1Ceria may be approved by che Healch Officer if such deviation is
found cO be reasonably necessary in a parcicular case and will not
resulc in a less effeccive cank. In any such case the Health
Of ficer may require the applicant to submi e plans and specifications
of such cank prepared by a licensed civ11 engineer.
603 Star.dard Drainfield Desistn
A. Dual D:oainfields : Dual drainfields, each containing 100% of the
required absorpcion area, shall be required. Ihe dual drainfields
shall be conneceed co ehe septic tank by an approved diversion valve
which allows alternacing use of each drainfield. Ihe top of the
diversion valve shall be ac or above ground surface or placed in an
access box with iCs cover at or above ground surface to allow easy
access.
-16-
B. Sizin~/Absorocion Area: Dra1nfields shall be sized accordiq co the
m1nim= absorpcion area calculaced fro::! che follo'.i ng Cable ac.e.
Figure 2 an che basis of observed pe rcolacion raCes.
Percolac1on Race Nax1mu::! Sew aile Loa<ling
(m1n/in) Race (~al/fcZ/dav)*
less chan 1 Syscem prohibiced
J.... ... .... .......... ............... ...... .1.2
lO............~.............................O.~
. 24..........................................0.6
. .
30.........................................0.56
45.........................................0.45
60.........................................0.35
90 - 120.....................................0.2
Greater than 120 Syscem Prohib1ced
**erfective inf1lcracive surface is che crench sidewall area
below the invert of the drainpipe.
C. Trench Dimensions. See Figure 3 for (typical Cross-Seccion)
1. Depth. !tini mum effective cr ench depch shall be 1Z inches.
Ma~mun trench depth shall be 8 feet.
Z. Width. Minimum trench width shall be 18 i.nches ; max1:num. trench
width shall be 30 inches.
3. Spacing. Minimum spacing between trench walls shall be
calculated as twice the effective trench depch plus an ad-
di tional foot for each S7. drainfield area slape over 2u7.. In no
case shall the trench spacing (center-to-center) be less than b
feet.
4. Length. The required length of draint _eld crench shall be
determined in acco rdance wicn. ehe loading - absorption area
req ui rement c:1 ted in Suo-section 6U3 B. No single trench shall
be mare than 100 feet in length.
S. Pipe Slope. The drainf1eld pipe sn.all be laid level, with a
maximum grad1ene of 3 inches in lUO feee.
-17-
)
6. Cove r. Minimum d1:nension from ground surface to the cop or che
drain rock shall be as follows :
Orainfield Cover
Sloce Reauired
0-10% 12 inches
10-15% 24 inches
Over 20% 30 inches
D. Confi~uraC1on. Drainf1eld trenches shall be arranged co achi eve
serial distribution as indicated in Figure 4.
E. Macer1als.
1. Solid and perfo raced drainHeld pipe shal.l be )-inch or 4-inch
(inside diameter) rigid"plastic (PVC, AllS. or equivalenc) wich a
lIl1n:lmUIII crushing strengtl1 of 1,500 psi, clearly IIlarked on the
pipe. Corrugaced pipe is not percitted.
2. Drain rock shall be clean, durable 3/4-inch to 1 1!2-inch crushed
rock or gravel.
3. Silt barr iers snal.l consist of un treated building paper, three
inches of straw, filter fabric, or other material approved by the
aealth Officer.
F. Reserve Area.
1. A reserve area may be required as a condition of a variance from
other elements of these regulations.
2. Reserve areas shall m.eet all site suitability requir~enl:s
outlined in these regulations and snal.l not be used for con-
s truc tion of buildings or roadways or fa r otner incompatible or
soil-damaging activities.
604 Modified Drainfield Desi~ns
A. Fill S.,.. tems. Where soil and/ or groundwater cOMi tions require
shallow trclllch plac emen t , soil flll may be uS ed to satisfy drain-
Held cover requirements. Typical cross-section details are shown
in Figure S. Such flll s ys t eIllS snal.l comply witn all sice
suitability and do;sign criteria ror scandard systems as <Jell as che
following requirements:
1. Ground Sloee. MaximUIII allowable groundslope shall be 12 1/2 7..
2. Percolation Rate. Percolation ['ate shall nol: be slower tnan 60
min./ inch.
-18-
3. Drainfield Trenches. The drain rock and perforated pipe sections
shall be installed entirely Within native soil. Systems in .nich
effluent is proposed to be discharged into fill shall be
cons idered under the AHernative Design Category - See Section
800.
4. Site Preparal:ion. Prior to placanent of fill m.a cerial, all
vegetation shall be removed and the ground surface di sc ed or
plowed to pennit good mixing of native soil and fill material.
5. Fill Material. The soil used for fill shall be similar in
texture to the native so11. Sand, gravel or rock do not qualify
as acceptable material for cover fill. The f111 shall be placed
prior to excavation of drainfield trenches.
6. Canoace1on. Fill shall be placed in layers of not lllOre than
eight (8) inches, and compacted to approximately the same dry
density as the native soil. Results of so11 density tests may be
required to be submitted to the Health Officer. Alternative
cClllpaction procedures may be allowed in acc.ordance with re-
cClllmendstions and suppo rting technical data. supplied by a
registered civil engineer.
7. Covera,o;e. The f111 shall be COQc1nuous and cons truc ted to a
uni fo rm depth of at least 12 inches over all drainfield
trenches. The fill shall extend a minimum distance of 15 feet in
any direction frCIII the center of any trench. The toe of the fill
should be tapered at no less than a 5:1 racio, beginning 15 feet
frCIII any drainfield trench.
8. Land and Subdivisions. Land divisions for which fill systems are
necessary for approval of sewage dis posal suitability shall be
required to record a declaration of restrictions approved as to
fo rm by the County Counsel.
B. Effluent PUlIIp. Where topography will not allow gravi ry flow frQlll
the septic. tank to the drainfield. the individual sewage dis posal
system shall include an effluent pump and sump. Typical pump and
SUlllp details are shown in Figure 6.
1. PUlIIP: The pump s hall be of the sue and type to accCIIIlllOda te the
intended use and shall include the following:
a. A "Hand-off-auto" (HOA) switch.
b. An audio and visible alam and necessary sump water sensing
device to indicate a "high water" condition.
c. Either a "pill" or mercury float switches for starting and
stopping .
d. A min1mum pumping volume of 100 gallons between the pump's
start and stop levels.
-19-
)
e. The pump co be seC a minimum of 4 inches above che SllIllp
boc cem.
2. Sump:
a. The SUlllp shall have an oveeall wo C><<in" capacicy (below che
inlec from che sepcic tank) of abouc 1 1/2 ci","s che des ign
daily sewage flow. This capacicy shall include che no nal
operacing dose volume plus 24 hour eme rgenC'f s c.orage
capacil:y foe periods of pump failuee oe powee oucage.
b. In lieu of 24 hour emergency scorage capacicy, an aucomacic
bypass co a sepaeace scorage cank oe emeegency leaching area
may be provided.
c. The sump shall be eicher concrece, concrece block or fiber-
glass.
d. Access shall be provided by a minimum 2a-inch manhole.
e. All pipes and/or eleccrical conduiCs chrough che sump shall
be eicher precast. inca che sump or seal ed wich gas-cighc
canpress10n connectors.
3. Electrical FeaCures: The following electrical feacures shall be
prov1ded :
a. An ou cd oor-cype concrol box concaining fused disconnecc and
lIlCcor procection swi cch.
b. The control box shall be moun Ced on che building se rved if
located wichin 20 feec of Che sump, ochenn.se che con ere 1
box shall be mounced on a pipe scand or wooden posc.
c. Eleccrical conduic shall be PVC. Separace condulcs shall be
provided foe control wiee and powee supply.
d. A high watee audio and visible alarm shall be locaced wichin
che building seNed by che sewage disposal syscem.
4. Pressure Piein.;:
a. The pipe from che SUlllp co che drainfield shall be solid
plascic, schedule 40, and sized co meeC pumping and ef fluenc
flow requirements while minimizing frictional losses.
b. A union, swiog check valve and double wed ge gace valve
mounted in Chis order. ( aJJay from Che pump) is required
eicher in che SUlllp or adj acen c co che SUlllp in a concrete
box.
c. Concrece chcusc blocks shall be required at sharp changes in
piping direccion.
-20-
5. Permics: Aside from an individual sewage disposal syscem per.n1c,
addicional permic(s) will be required by che Building Inspeccion
Deparcnenc for pump inscallacions.
C. Drainage Improvements. Surface and sub-surface drainage r"a,cers
s hall be dive reed from the d rainf ield area.
1. Surface Flows. Any concentrated drainage flow fran buildings,
ya rds, drives, etc. , shall be diverted away from. the drainfield
area. Ihis may require sice grading and installation of a
diversion ditch or berm all che upslope side of the drainfield
area.
2. Sub-surface Flows. Ihe use of intercept drains to lowe r the.
1 evel of perched groundwater in the immedia te drainfield area
shall be acceptable under the following collditiOllS:
1. Natural ground slope is greater than 5%.
2. Site investiga tions show groundwa ter to be pe rched on a
clearly definable layer of bedrock, hardpan or impe rmeable
soil.
3. Ihe intercept drain shall be ins talled all che upslope side
of the drainfield area as follows : (See Figure 7 for
cypical construction decails).
a. Ihe incercept drain shall be a minimum of 12 inches wide
alld shall extend from ground surface into bedrock,
hardpan or the impe rmeable soil layer a minaum of six
(6) incl1es.
b. Pervious sections of the intercept drain shall be
separated frcm the drainfield and septic tanl<. as fol-
lows:
upslope : minaum of 15 feet
laterally : minimum of 25 feec
d ownsl ope : minimum of 5U feet
c. The bottcm alld downslope side of the drain shall be
lined wich plascic film having a minimum thickness of 12
mils.
d. The drainage crench shall be filled wi th 3/4 to 1 1/2
incl1 drain rock, wich perforated 4" drainpipe along and
2" above che boccom of the trench.
e. Filcer fabric, .craw, graded aggregace or ocher suicable
filter ma terial shall be placed 1mmediacely above Che
dr ain ro ek.
-21-
)
f. The trench shall be backfilled to the surface with 6 to
12 inches of soil.
g. A constant, minimum fall of at least 17. and gravity flow
shall be maintained throughout the drain toward the
ou tiet point.
h. The downslope outlet shall be protected against blockage
or damage through the use of screening t rock cove r,
junction box or other suitable means.
i. A surface drainage diversion di tch shall be installed
upslope of the intercept drain.
4. Engineering plans shall be provided to d elW ns era ce com-
pliance wi th the above provisions. Where the po tential
ef fect iveness of the intercept drain is not clear, the
liealth Officer may ,require such drain to be ins talled and
demonstrated effective prior to issuance of an individual
Sewage Disposal Sys tem.
700 INSTALLAIION AND INSPECTION
701 General :
1. Sewage disposal sys tems shall be installed in accordance with plans
approved by the Health Officer except for minor deviations. eha nges
in sewage disposal plans must be approved by the Health Officer
prior to installation.
2. All systems shall be constructed by licensed contractors except that
systems for single-family res idences may be installed by the
property owner.
702 Septic Tanks:
I. Septic tanks shall be installed level on a firm bedding of compacted
so ll, saad 0 r rock.
2. In areas of high groundwater, septic tanks shall be demons cr aced to
be water-t,ight, including field testing, if necessary.
703 Drainfields:
1. Trenches should be cons t rue ted when the soil is dry to mini:n~ze
unnecessary soil compaction and smearing of trench sidewalls.
2. Smearing of the infiltrative surfaces (trench bottom and sidewalls)
during const.ruction shall be corrected by scarif y1 ng the
infiltrative surfaces after excavation is complete.
3. Surface runoff shall be prevented fran entering open trenches during
construction to aJin.1mize silcacion at the crench bottom area.
-22-
4. BackfUl shall be placed so as to maximize surf ace runOr! and not
crush drain lines.
5. Erosion protection in the drainfie1d area shall be required upon
completion of installation.
703 Insoections:
1. All installations shall be inspected by the Health Officer befo r.e
they may be considered complete.
2. The Health Officer shall be notified at least twenty-four (24) hours
prior to installation of the system to allow inspection of trenches,
septic tank and related features.
3. Sewage dis posal sys tems requiring pump installations or other
elect rical features shall be inspected by the eounty Building
Inspector.
4. In ad di tion to items 1, 2 and 3 above. alternative sys tems shall
require ins pection, testing and certification by . the engineer of
record. Such inspection work shall be conducted in accordance with
recanmended proc e.d ures proposed by the engineer and approved by the
Health Officer. (See Section 800 Alternative Systems.)
800 ALTERNATIVE SYSTEMS (SEE SEPARATE PACKAGE)
900 WAIVER OF RECULATIONS
901 General:
Waiver of any of the regula tions contained herein may be granted by the
Health Officer when, because of Special circumstances applicable to the
location, soil characteristics, or surroundings. the strict application
of these regulations would depr ive such property of privileges enj oyed by
other property in the vicinity, provided, however, that no waiver shall
be granted if reduction of requirements would present a threat to water
quality or pubUc health.
902 AD plication:
Applications for waiver(s) shall be made in writing on a form prescribed
by the Health Officer, and shall be accompanied by appropriate technical
information or report(s) suppor~ing the waiver request.
903 Review and Determination:
Upon. receipt of the application and supporting informaCion, the Health
Officer shall review the request and conduct an inves tigation to
determine whether a waiver should be gran ted under the provisions of
Section 901 above. The Regional Water Quality Control Board shall be
notified of the wa1ver application and the Health Of ticer's inves-
tigation. After conclusion of the investigation, the Health Officer
shall prepare a written order granting or denying the waiver, and shall
include in such written order specific findings of fact and reasons for
its granting or denial.
-23-
,
)
904 Nonconformiru>; Lots:
This sect.ion shall not be construed to allow the creation at new suo-
standard or nonconfo rming laCS or parcels. except with the exp11c.it:.
approval of the Board of Supervisors, and upon a showing of good cause
and a finding that such variance will not be inj urious to the public
health.
905 Geastraphic.al Area Waivers:
From time to time, the Health Officer may consider the issuance of
wai vers to s pec1f ic provis ions of these regulations for general
geographical areas of the coon ty. Such geographical area waivers ~y be
cons idered in res pense to ap plication( 5) by 1ndi viduals or solely upon
the initiative of the Health Officer. Adequate technical justification
must be pr esented in support of such waivers, and will be subj ect to
re'liew and concurrence by the San FranciscO Bay Regional Water Quali ty
eoncrol Board. Geographical area waivers adopted as provided here will
be incorporated into these regulations.
906 Stinson Beach Area:
Stinson Beach is formally escablishea as an on-sice wastewater management
area. Standards for sewage d1s pos al at Stinson Beach are set forth in
the "'Was cewa ter Managemenc Program; Rules and Regulations" , adopted by
the Stinson Beach Waste Quality District, which are incorporated here by
reference.
-24-
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-26-
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FIGURE' 3 TYPICAL DRAINFIELD TRENCH DETAILS
-27-
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FIGURE 4 SERIAL DISTRIBUTION DETAILS -
-28-
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! COUNTY~",
. COMMUNITY 0 ~~MElIIT^:(;.~Y
a o iii,,) ''''''~''-'''''
, pq-~.; \Jj- f. :";,-:',O;'j
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5 1990 Environmental Health Services
DE~:;F:l ~-, ''"''' Civic Center, Room 283
CO'~ ' III ."'.' {"'r' San Rafael, CA 94903
:J,M1 1N/"'"v i'"' ..:... I, i ~).- (415) 499-6907
..Jj...., J I i..Jf:'Vi':"1 .....,~.
- >:...~UJ-','r~','- FAX (415) 507-4120
":::::I'! ENVIRONMENT AL HEALTH SERVICES POLICY MEMORANDUM #1
SUBJECT: Individual sewage disposal system guidelines for the remodeling, addition
and/or change in use to an existing structure.
References:
Marin County Code, Chapter l8.06,
Marin County Regulations for Design, Construction and Repair ofIndividual Sewage Disposal Systems,
Unifonn Plumbing Code
Background:
These guidelines establish criteria to be followed for projects involving the remodel, addition, and/or
change in use of a residential or commercial structure. It is the intent of these guidelines to further
define the extent of a remodel, addition and/or change in use that can be accommodated when the
individual sewage disposal system is not currently or cannot be constructed in full compliance with the
Marin County Code.
Statement of Purpose:
It is the intent of the Marin County Community Development Agency (CDA), Division of Environmental
Health Services, to provide the highest level of public health protection while, at the same time,
accommodate the public's need for modifying existing structures and uses. The policy below is meant to
provide unifonn and consistent guidelines for Environmental Health Services staff and the public to
follow when considering a remodel, addition and/or change in use to an existing structure or property.
Policy:
The criteria established below shall be followed in the consideration of all applications. In the case
where the appropriate criteria cannot be specifically detennined, conditions may be attached to the
project as specified in Section V.
o I'RINrED ON RECYCLED rArER
Page 2
EHS Policy Memorandum # I
SECTION 1
Criteria
The following provisions set forth individual sewage disposal system requirements by system class based
on the extent of proposed remodel, addition or change in use to an existing structure or property. (Note:
If the subject property is within 400 feet of a public sewer, modifications to an individual sewage
disposal system may not be permitted pursuant to Section 18.06.050 of the Marin County Code).
A. Status oflndividual Sewa~e Disposal System Definitions
Class I: The individual sewage disposal system is in compliance with current Marin County
Regulations for Design, Construction and Repair of Individual Sewage Disposal Systems
(Standard Systems or Alternative Systems, Category 2 or 3 may apply)..
Class II: The individual sewage disposal system complies with the requirements established for
Repair of Existing Systems (Marin <;ounty Regulations for Design, Construction and Repair
of Individual Sewage Disposal Systems, Section 304).
Class li: The individual sewage disposal system has been permitted by the Health Officer pursuant to
Chapters 18.04 or 18.06 of the Marin County Code. In addition, a performance evaluation
report has been prepared by a qualified professional who has determined that the system is in
good working condition and does not pose a threat to water quality or public health. The
evaluation report must include, at a minimum, a site plan which delineates the location of the
individual sewage disposal system, all structures located on the property, nearby geologic
features, such as, cutbanks and creeks, water wells, reserve area, property slope, projected
water use data, projected wastewater strength, and any other item determined to be necessary
by the Health Officer in order to adequately evaluate the system. If the leachfield is not a
dual 100% system or does not have a dedicated reserve or fail-safe area, an adequate reserve
area must be located and sited.
Class IV: Cesspools (as defined pursuant to Section 104(b) of the Uniform Plumbing Code, 1991
Edition) or other systems for which no documented records are available.
B. Discussion
The satisfactory performance of a Class I and Class Il individual sewage disposal system must be
substantiated by qualified professionals, usually either a registered civil engineer' or registered
environmental health specialist. Inspection and/or verification by Marin County Environmental Health
Services staff may be required. Individual sewage disposal system performance inspection procedures
are shown in Attachment A. Waivers in siting and design may be approved for Class I systems provided
technical merit is submitted, substantiated and approved by Environmental Health Services. No waivers
will be allowed for reductions in setback to groundwater, surface water, or adjacent wells, the
requirement for dual 100% leach fields or fail safe area, or when the Health Officer finds that a threat to
water quality or public health could result. For Class Il systems, waivers to either Standard System
design and siting criteria or Alternative System design and siting criteria (Category I, 2 or 3) may be
approved, provided the Health Officer determines that a threat to water quality or public health would
not result. A Class IV system may be approved for any required safety and/or structural improvements
to a structure provided the Health Officer determines that the cesspool poses no threat to water quality or
public health.
"---- --------- ~-- -~
--
Page 3
EHS Policy Memorandum #1
SECTION II
Residential remodel. addition andlor chan~e in use
Proposed Extent of Remodel and/or Addition:
A. Addition of New Bedrooms: An adequately sized Class I system is required.
Note: For the purposes of determining number of bedrooms or the minimum number of
bedrooms based on the square footage of the residence, Section 204 of the Marin County
Regulations for Design, Construction and Repair of Individual Sewage Disposal Systems shall
be used.
B. Addition Other than Bedrooms:
Addition:
Increase (SF)" Minimum Class Required
0-20% III
21% - 39% II
40% and over I
C. Remodel of Existing Habitable Space:
~ Minimum Class Required
0-20% III
21% - 39% II
40% and over I
Note: "The above percentages are in reference to the square footage (SF) based on the original
building permit for the structure.
D. No remodel and/or addition project will be permitted with a Class IV system.
E For a project proposing both a partial remodel of a building and an addition to the same building,
the combined total of both areas shall be used to determine the required class of system.
F. Detached accessory structures which do not propose bedrooms and/or additions of habitable
space (i.e., garage, workshop, storage building, swimming pool, bam) to an existing structure:
1. Class I, II or III system may be permitted provided that the individual sewage disposal
system is found to be in good working condition and not pose a threat to water quality or
public health. Satisfactory performance of the system must be demonstrated prior to
approval of the accessory structure. An individual sewage disposal system evaluation report
prepared by a registered civil engineer or registered environmental health specialist shall be
submitted to Environmental Health Services. Inspection and/or verification of the above
may be required by Environmental Health Services staff. All required setbacks must be
maintained and encroachment upon or usurpation of a required fail-safe or reserve area is not
permitted.
Page 4
EHS Policy Memorandum #1
SECTION m
Commercial addition. remodel with no change in use
A. Remodeling which does not involve structural changes in floor area, height, bulk, or mass and
does not add to the loading of the individual sewage disposal system or strength of the
wastewater may be approved provided the system is evaluated by a qualified professional and
found to be in good working condition pursuant to a submitted evaluation report, and pose no
threat to water quality or public health. Inspection and/or verification of the above may be
required by Environmental Health Services staff.
System Class: Septic systems may be Class I, II or III.
B. Addition to Existing Commercial Space:
Increase (SF) Minimum Class Required
0-20% III
21%-39% II
40% and over I
C. Remodel of Existing Commercial Space:
(SE) Minimum Class Required
0-20% III
21% - 39% II
40% and over I
D. For a project proposing both a partial remodel of a building and an addition to the same building,
the combined total of both areas shall be used to determine the required class of system.
E. No remodel and/or addition project will be permitted with a Class IV system.
SECTION IV
Commercial addition. remodel with change in use
A. If the project has the potential for increasing sewage loading and/or sewage strength based on
review of an engineering report and subsequent determination by the Health Officer, a Class [
system will be required.
_.. - --
--
Page 5
EHS Policy Memorandum #1
SECTION V:
Conditions of project approval
In addition to the conditions set forth above, the Health Officer may apply conditions of approval to a
proposed project in order to ensure protection of water quality and public health. Such conditions may
include, but not be limited to the following:
A. Conditional sewage disposal permit
B. Deed restriction
C. Operational Permit for the individual sewage disposal permit
D. Any combination of the above or other conditions as determined to be necessary by the Health
Officer.
SECTION VI:
Appeal Process
Any person who disagrees with the decisions or subsequent actions made under this policy can appeal
such decision or action rendered as a result of this policy pursuant to Marin County Code, Section
18.06.140.
EFFECTIVE DATE
This policy will be effective 1~. I . If!.. and will remain in effect until canceled or superseded.
,
e&~
Edwarcfstelart --
Chief, Environmental Health Services
F:\PROGRAM\SEPTlaADDR.EM2.OQC 211/96
! COUNTY OF MARIN
. COMMUNIlY DEVELOPMENT AGENCY
a
, "~,j
- "'\
Environmental Health Services
Civic Center, Room 283
San Rafael, CA 94903
(415) 499~907
FAJ((415) 507-4120
SEPTIC SYSTEM PERFORMANCE EV ALUA TION GUIDELINES
INTRODUCTION
The purpose of these inspections will be to determine, on an individual basis, whether
existing septic systems are functional and meet minimum standards of performance
established by the San Francisco Regional Water Quality Control Board (RWQCB) and the
County of Marin, Environmental Health Services (EHS). The following performance criteria
are established as minimum requirements:..
1. There is no surfacing effluent at any time.
2. The effluent is not discharged direetly to groundwater. This means that site ground
water levels may not rise above 36 inches below the leachfield lines.
3. There is always positive flow from the leachfield and from the septie tank with no
backup to the tank or house plumbing during high groundwater eonditions.
4. There is an adequately sized septic tank for the structure being served and it must be
serviceable - e.g. access riser for maintenanee. The septic tank must be water tight
and constructed of approved materials.
The following sets forth procedures in condueting performance evaluations, to assure
eonsistency and thoroughness in verifying the funetioning status of existing septic systems.
INSPECTION RESPONSIBILITY
The inspections shall be carried-out by a Registered Civil Engineer or Registered
Environmental Health Specialist. The individuals conducting the field inspection work shall
be well-versed in the operation and maintenance of on-site sewage disposal systems and
trained specifically in the testing and inspection procedures outlined in this document.
BACKGROUND DATA
Prior to eonducting the field performance inspection all background information pertaining to
the property and septic system shall be eompiled and reviewed. This should include permit
information, site plan, "As Built" drawings of the septic systems, prior sanitary survey
inspection results, etc.
(Attachment A) FIPROGRAMISEPT1CIPERFEVL.DOC 11/3/95
@ rll.lNTED ON REC'tCLEO r...rER
Page 2 .-
-
Septic System Performance Evaluation Guidelines
The site plan must show the location of the septic tank and leachfield, the locations of all
buildings, decks, cutbanks, creeks, wells, reserve or fail-safe area, direction and pereentage
of slope, or any other items which may affect the septic system. If a reserve or fail-safe area
is not specified or if any proposed construction encroaches upon it, a new reserve area must
be identified. The evaluation must address system performance during wet weather
eonditions as well as dry weather conditions.
INITIAL SITE RECONNAISSANCE
Initially, the inspector should walk the property to confirm the location of the septie tank,
leachfield, and other pertinent features of the system. In verifying the leachfield location, the
length of each line and the depth of the drainpipe (below ground surface) shall also be
determined for comparison with observed groundwater conditions. This may require probing
with a metal rod or actual excavation.
The septie tank and disposal field areas should be checked for any obvious signs of existing
system problems such a surfacing effluent, odors, greywater bypasses, selective fertility (Le.,
lush vegetation in the leachfield area) or any other eondition that may suggest an existing or
impending problem. The inspector should determine if the system has dualleachfields, and,
if so, locate and eheck the diversion valve, (a) to see that it is functional; and (b) to
determine whieh leachfield is in serviee. All observations should be noted.
As part of the initial site reconnaissanee a hand-augured boring (3-inch minimum) shall also
be made alongside (but not within) the leachfield area for observation of groundwater
eonditions. An initial reading (Le., depth to groundwater from ground surface) shall be taken
when the boring is made. The boring shall then be left open for the remainder of the
performance inspection so that a final reading may be taken after the water level has been
allowed to stabilize for about 1-hour. The boring should be backfilled before leaving the site.
SEPTIC TANK INSPECTION
After the initial site reconnaissance has been conducted, the detailed inspection of the
system should commence.
Aecess Risers
First, locate the septic tank and determine if permanent access risers have been installed on
the septic tank. If the tank is equipped with risers, check their general condition. Ideally, the
risers should be properly grouted to the top of the septic tank to prevent groundwater and/or
surfaee water intrusion. The lids of the risers should also be properly sealed to prevent odors
and the entry of insects, (e.g., flies, mosquitoes, etc.). Any observed defects in the access
risers should be noted. If the tank lacks access risers, this information should be so noted;
and the property owner should be provided information about access risers and shall be
required to install them.
-_._--,-~ -; - -.-.-
. , ~-~
."
Page 3
Septie System Performanee Evaluation Guidelines
Opening the tank
After inspecting the access risers the septic tank lids should be carefully removed. Care
must be taken if gardens and shrubs are near to prevent damage and to disturb the yard
area as little as possible. Concrete lids are heavy and may be "cemented" in plaee by silt. A
steel bar or other suitable tool may be needed to assist in opening the lids. During the tank
inspection process, personnel should wear protective boots and gloves (neoprene) to guard
against infection from pathogenic organisms.
Structural Condition
Once the tank is open, the inspeetor should observe and probe the struetural condition of the
septic tank to check for any obvious signs of cracking or other structural defects in the tank.
A steel rod is used to probe the walls and tlottom of the tank. Normally, the tank will not
need to be pumped-out to perform this procedure. The inlet and outlet sanitary "tees" should
also be inspected to assure that they are in satisfaetory condition, properly positioned, and
free of seum aecumulation, rocks, root matter or other obstructions. Any problems should be
noted and the inspector shall conduct whatever additional tests or observations necessary to
verify the structural integrity of the septic tank.
Liquid Level
The liquid level in the tank should be measured with respeet to the outlet pipe. In a properly
funetioning system, the level in the tank should be even with the invert (i.e., bottom) of the
outlet pipe (see Figure 1). If the liquid level is below the outlet pipe, the tank is leaking. If
the liquid is above the pipe, the leachfield is either flooded or obstructed. The depth of water
above or below the outlet pipe should be measured and noted.
Tank Capacity
The capacity of the septic tank (in gallons) shall be determined from measurements of the
width, length and depth (below outlet pipe) of the tank. The capacity shall then be compared
with the established water use/wastewater flow rates for the property. A minimum septie
capaeity of 3 times the maximum expected daily wastewater flow rate shall be required for
the existing septic tank size to be judged adequate. If this criteria is not metor there is any
uncertainty regarding compliance, then additional tank capacity is required.
Page 4
Septic System Performance Evaluation Guidelines
,
HYDRAULIC LOAD TEST
General
The inspector should then proceed with the hydraulic load test of the septic tank and disposal
field. The test, as described here, is condueted only for standard gravity-fed leachfields, and
does not apply if the system utilizes a pump. A separate test to be conducted for pump
systems is described in the next seetion. The hydraulic load test is conducted by surcharging
the septic tank with about 150 gallons of water over a 20 - 30 minute period; and then
observing the rise of water in the tank and the subsequent draining process. (Tracer dye
may be used to assist in observing leachfield failure). A garden hose discharging into the
outlet side of the tank can be used to sureharge the tank. The hose outlet should remain well
above the water level in the tank to prevent cross contamination. Before starting the test, the
flow rate from the hose should be determined (i.e., with 5-gallon bucket and stop wateh) to
properly gauge the amount of surcharge water added to the tank. Alternatively, a portable
water meter can be installed between the house faucet and the hose to directly measure the
water volume added.
Test Procedures
The step-by step proeedures for the hydraulic load test are then as follows:
. Measure the location of the static water line in the septic tank (at the outlet side) as an
initial reference point.
. Begin surcharging the tank with water to start the hydraulic load test.
. Observe any rise in the liquid level at the outlet pipe and measure the water level at the
end of filling. Typically, the liquid level will rise from 0.5-to 1-ineh, at which point the
liquid level should stabilize for the reminder of filling; and the return to the initial level in a
matter of minutes after filling is stopped.
. After the filling cycle is finished, the water level decline in the septic tank is observed until
the initial level is reached; and the time to achieve this is recorded. If the initial level is not
attained within 3D-minutes, the test is terminated and the final water level is noted.
System Rating
Based upon the water level readings during the test, a hydraulic performance rating shall be
assigned to the system in accordance with the guidelines provided in Table 1. It should be
emphasized that these are guidelines only, and special circumstances may be cause for
modifying the evaluation and rating of particular systems. A system receiving a "Failed"
rating shall require appropriate upgrading.
- ---~- I -- -.
Page 5
Septic System Performance Evaluation Guidelines
FINAL LEACHFIELD INSPECTION
At the completion of the hydraulic load test, the drainfield area and downslope areas should
be checked again for indications of surfacing effluent, wetness, or odors. If any of these
eonditions exist as a result of the hydraulic load test, this shall be considered conelusive
evidence of system failure. If the field observationS of wetness are not obviously the result of
the hydraulic load test, further investigation may be necessary to determine if the drainfield is
failing and the cause of the failure. Additional investigative work may include water quality
sampling (for total and fecal coliform, ammonia and nitrate) or dye testing. The cause of
seepage eould be related to gopher holes, site drainage or erosion problems, excessive
water use or simply the age of the disposal system.
PUMP SYSTEMS
For systems equipped with an effluent pump, the following inspeetion procedures should be
followed. Fiqure 2 provides a diagram of a typieal pump system installation for referenee.
General
Remove the pump access cover and basin lid, taking care that no soil or other material
enters the basin. Note any signs of scum or sludge buildup, indications of previous pump
failure (such as scum line above the high water alarm switch), or evidenee of soil or roots
entering the basin. Also, inspect the fioat controls to see that they have free movement, and
cheek the eleetrical junction box (if located in the basin or aecess riser) for any obvious signs
of corrosion. If the water level in the basin is normal (i.e., between the high and low water
eontrols) proceed with testing of the pump systems.
Pump Test
The pump test is condueted by adding sufficient water to the basin to aetivate the pump "on"
control, and observing the performanee of the system over at least one pumping cycle. The
total amount of water added should be about 150 gallons, to approximate the same hydraulie
loading of the leachfield as for gravity systems. Using a garden hose, the water may be
added to the outlet side of the septic tank, or directly to the pump basin. If filling the basin
direetly, eare should be taken to minimize turbulence and disturbance of sediment or sludge
that may have collected in the basin. This can be best accomplished by directing the stream
of water against the interior side of the chamber, rather than directly toward the bottom of the
pump chamber.
Page 6
Septic System Performance Evaluation Guidelines
,
Observe the filling of the basin, and note and measure the point at which the pump is
activated. Immediately stop the filling operation and observe the pumping cycle until the
pump shuts-off. While the pump is discharging, examine the piping system for any leaks.
Even small leaks could be a forewarning of possible breaks in the pressure line at some point
in the future; and these should be corrected as soon as possible. Note and measure the
depth at which the pump shuts-off, and calculate the volume of water between the "on" and
off" measurements. Compare this dose with the design dose volume specified for the
system. If the dose is too high or too low, float eontrols should be readjusted to correct the
dose. Any adjustments to the pump system should be done by a licensed and properly
qualified contractor (not by the inspector).
The pumping cycle (from "on" to "off') levels) should be timed and the results recorded on
the inspection form. Typically, if the pump is sized and operating properly, pump operation
lasts 1-5 minutes per dose. Pump cycles lasting longer than this may indicate leachfield
clogging and/or pump deficiencies. If this is observed, it should be noted and further
investigation of the pump and leaehfield should be eonducted to determine the speeifie
cause.
If during filling of the basin, the pump does not aetivate when the water reaehes the high
liquid level eontrol (i.e., "on" float), discontinue the pump test. This indicates a pump failure,
defective float switch or wiring problems and will require the repair service of a competent
eontractor familiar with these types of systems. The pump system failure should be noted,
communicated immediately to the residenUowner, and followed-up with a notiee requiring
prompt corrective aetion.
Leachfield Inspection
At the completion of the pump test, the disposal field area shall be cheeked for signs of
seepage in the same manner as done for gravity-fed systems following the hydraulie load
test.
Clean-Up
At the eompletion of the septic system inspection and testing, the inspector shall replaee all
aceess lids and clean all tools before leaving the site. All tools, and equipment that come
into contact with wastewater should be cleaned and disinfected with a 1:5 bleach solution;
and all eontaminated rinse water shall be disposed of in the septie tank.
-~ ~ r~ ------ ~-
Page 7
S~ptic System Performance Evaluation Guidelines
TABLE 1
HYDRAULIC LOAD TEST RATING GUIDELINES
,
RATING SEPTIC TANK RESPONSE TO HYDRAULIC LOADING
EXCELLENT No noticeable rise in water level during filling.
GOOD Maximum water level rise of about 1-inch,
with rapid decline to initial level within 5-
minutes after end of filling.
SATISFACTORY Maximum water level rise of about 2-inches,
with decline to initial level within about 15-
minutes after end of filling.
MARGINAL Maximum water level rise of about 3-inches,
with decline to initial level within about 30-
minutes after end of filling.
POOR Water level rise of more than 3-inches, with
decline not reaehing initial level within 30-
minutes after end of filling.
FAILED Water level rise of more than 3-inehes, with
no noticeable deeline within 3D-minutes after
end of filling.
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FrGURE 2 EFFLUENT PUf1P AND SUf1P DETAILS
-
CHAPTER 18.07 fH;;:-~r--. ...
ALTERNATIVE SEWAGE DISPOSAL SYSTEMS . =rr-;:,;!;~:;,,~.7"".tD
....-.--=.'l_i1f"".."eJ
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I OWN OF TiPUo'''''~J
Sections: ...... l.\....<J
18.07.010 Purpose. . IWR :5 1998
18.07.020 Applicability .
18.07.025 Coastal zone. Dr:P;t""~~,l-' _
, '- "-"." i;\I~'~'\~ I ,-.....
18.07.030 Definitions. CO"'iJU' '''-', '..if'
i'hJ'J ;j~lTY~J:'ll(-'"''''''
,.;' ,~,l'" 'V':-~ rT
18.07.040 Prohibited acts. '- -~Lin':::J'1
18.07.050 Connections to public sewer system and alternatives.
18.07.055 Building permit approval.
18.07 .060 Regulations.
18.07.065 Permit required.
18.07.070 Application and fees.
18.07.075 Site evaluation.
18.07.077 Cumulative impact assessment.
18.07.080 Application process.
18.07 .085 Health Officer review.
18.07.090 Construction permit.
18.07.095 Certificate of installation.
18.07.100 Operating permits.
18.07.105 Waiver/Variance
18.07.107 Public hearings
18.07.110 Permits - nontransferable
18.07.120 Performance monitoring and reporting.
18.07.130 Abandoned alternative sewage disposal systems
18.07.140 Permits - revocation
18.07.150 Abatement
1807.160 Enforcement.
18.07.170 Appeals.
18.07.180 Penalty for violations.
18.07.190 Severability.
18.07.010 Purpose. The provisions of this chapter are intended to insure that the disposal of sewage by
means 01 an alternative sewage disposal system shall be accomplished in a safe and sanitary manner in order to
protect the public health, safety and welfare to the greatest extent possible.
18.07.020 Applicability. This chapter is applicable to all alternative sewage disposal systems in the
unincorporated area of Marin County. This chapter does not apply to any industrial site which may discharge
sewage or industrial waste. However, where a governmental entity has entered into an agreement with the
Regional Water Quality Control Board and County Board of Supervisors to assume responsibility for
regulating or issuing permits to construct, repair, relocate, abandon, install, alter. modify or replace alternative
sewage disposal systems, then the provisions of this chapter shall not apply within the jurisdictional limits of
that entity for the scope of responsibility assumed by the entity.
18.07.025 Coastal rone. Any alternative sewage disposal system prqposed within the coastal zone, as defined
by the Coastal Act of 1976, may be subject to a coastal development permit pursuant to Chapters 22.56 and
22.57 of this code. Different standards, as set forth in Chapters 22.56 and 22.57, are applicable to projects
located in coastal districts.
D.,,..~ 1f'1
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18.07.030 Definitions.
CONSTRUCTION PERMIT. A p~rmit issued by the Health Officer which authorizes the construction of an
alternative sewage disposal system.
CUMULATIVE IMPACT ASSESSMENT. An assessment of potential impacts which may occur as a result
of the installation of an alternative sewage disposal system. The assessment examines groundwater mounding,
groundwater nitrate loading and may include other issues the Health Officer believes because of special
circumstances relative to the size, type, or location of the alternative sewage disposal system (or systems)
warrant such analysis.
HEALTH OFFICER. For the purposes of this title, the term "Health Officer" means the Marin County
Health Officer, the Chief of Environmental Health Services Division, or their authorized representatives.
INDIVIDUAL SEWAGE DISPOSAL SYSTEM. The term "individual sewage disposal system" means and
includes any system of piping, treatment devices or other facilities (excluding chemical toilets) that store,
convey, treat or dispose of sewage which is discharged anywhere other than into a public sewer system.
A. STANDARD SEWAGE DISPOSAL SYSTEM. A sewage disposal system which includes a septic tank
(with or ,',ithout the use of sump chamber dnci pump) by which method subsurface effluent is disposed of
through leach lines.
B. AL TERNA TIVE SEW AGE DISPOSAL SYSTE~,l. Any individual sewage disposal system which may
or may not include a standard septic tank for treatment. or does not include standard leaching trenches
for effluent disposal, which has been demonstrated to function in such a manner as to protect water
quality and preclude health hazards and nuisance conditions.
OPERATING PERMIT. A permit issued by the Health Ofticer which authorizes operation of the alternative
sewage disposal system and shall be renewed at least every two years or ?<; otherwise specified on a case-by-
case basis. The operating permit is intended to serve as the basis for verifying the adequacy of the alternative
sewage disposal system performance and maintenance. Operating permits are issued after granting of the
certificate of installation.
PERSON. The term "person" includes any person. tirm, association, corporation, or any members, agents or
employees of the foregoing.
PUBLIC SANITARY SEWER SYSTEM. The term "public sanitary sewer system" means any publicly owned
and maintained system of sewage conveyance, piping, or any part thereof, that transports sewage away from
the properties of origin to publicly owned and operated sewage treatment and disposal facilities.
SEW AGE. The term "sewage" means any and all liquid or solid waste substance, which is associated with
human habitation and/or which contains or may be contaminated with human or animal excrement or offal.
SITE EVALUATION. A site evaluation is an evaluation performed by a qualified professional in compliance
with the Marin County Regulations for Design, Construction and Repair of Individual Sewage Disposal
Systems to determine site suitability for the alternative sewage disposal system.
---- -~ -- ----- - -
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18.07.040 Prohibited acts. It is unlawful for any person to do any of the following:
a) Construct, abandon, modify, relocate, install, alter, repair or replace an alternative sewage disposal
system or a component element thereof, which system is subject to the provisions of this chapter,
without first obtaining a permit from the Health Officer in accordance with the provisions of this
chapter and regulations issued hereunder.
b) Construct, alter, rebuild, use, occupy or maintain any residence, place of business or other structure
where persons reside, congregate or are employed, which is not provided with a means of disposal of
sewage by connection to a public sewer system or an alternative sewage disposal system, without first
obtaining approval, construction permit, and/or operating permit from the Health Officer.
c) Construct, use, or maintain any alternative sewage disposal system in such a manner as to threaten
public health or water quality or overflow onto public or private land or affect any river, stream,
creek, spring, lake, pond, reservoir, swamp, ocean, bay, water supply or water system.
18.07.050 Connection to puhlic sewer system and alternative, Sewage disposal shall be by means of a
connection to a public sewer system if the neareq sewer is within four hundred lineal feet of the parcel in
which the structure generating the sewage is to be cunstructed or existing system is currently located. If at any
time a public sewer system is installed within 400' feet of a property currently without the benefit of such
public system and operating on an alternative sewage disposal system, that property shall be required to
connect to the new public sewer system at that time. This requirement may be waived by the Health Officer if
s/he finds connection to a public sewer is legally or physically impossible.
18.07.055 Building permit approval. Building permit applications for structures incorporating an individual
sewage disposal system shall be endorsed by the Health Omcer.
18.07.060 Regulations. The Health Ofticer is authorized to issue regulations, providing criteria to carry out
the purposes of this chapter. Such regulations shall be approved by the Board of Supervisors and Regional
Water Quality Control Board prior to their effectiveness. The Health Ofticer is authorized pursuant to Section
18,07.105 of this Chapter to grant a waiver/variance to any particular requirement imposed by such regulations
for the construction of a new alternative sewage disposal system if s/he determines that the general purposes of
this chapter will be achieved by such waiver/variance.
18.07,065 Permit required. Every person shall obtain permits as provided for by tbis chapter to repair,
replace, alter, relocate, install, abandon, modify, construct or operate an alternative sewage disposal system
unless installation of a standard sewage disposal system is feasible or connection to a sanitary sewer is
required,
18.07.070 Application forms and fees. All applications for alternative sewage disposal system site
evaluation, construction, or operating permits shall be submitted in writing to the Marin County Community
Development Agency, Division of Environmental Health Services, on forms supplied by the Health Officer.
The application shall be accompanied by fees as specified in the most recently adopted resolution of the Board
of Supervisors designating fees for Environmental Health Services.
18.07.075 Site Evaluation. Site evaluations shall be performed on all lots for which alternative sewage
disposal systems are proposed. Site evaluations shall include, but may not be limited to, a soil evaluation,
percolation tests and high seasonal groundwater determination. Site inspections may also be conducted by the
Health Omcer to verify compliance with any or all provisions of the regulations.
P;I~~ It.!,
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18.07.077 Cumulative Impact Assessment. Alternative sewage disposal systems shall also require an
assessment of potential cumulative impacts that could result from the installation of the alternative system.
Cumulative impact assessments shall be required according to the type of installation, the type of alternative
system and the type of cumulative impact issue of concern. The results of the cumulative impact assessment
shall be submitted for review to the Haalth Officer and may be grounds for denial or revision of the proposed
alternative system.
18.07.080 Application Process. Engineering plans and site data for alternative sewage disposal systems
shall be submitted in accordance with the Marin County Regulations for Design, Construction and Repair of
Individual Sewage Disposal Systems. Engineering plans for alternative sewage disposal systems shall be
signed by a Registered Civil Engineer or Registered Environmental Health Specialist. In addition to site data
and supporting engineering calculations, alternative sewage disposal system applications shall include the
following:
A. Contingency plan which outlines specific actions to be taken to repair, expand or replace the system.
should the need arise.
B. Construction inspection schedule which ident!fies critical points during the construction at which time
inspections will be made by the system designer.
C. Operation. maintenance and monitoring instructions which provide brief and simple guidelines to the
system owner(s) regarding the operation of the system, system owner responsibilities and system
monitoring needs
D. A grant of easement authorizing access by the Health Officer, Regional Water Quality Control Board
personnel and agents to the applicant's property for periodic inspection of system operation.
E. The applicant shall record a Supplement to Appl ication to Construct an Alternative Sewage Disposal
System on a form provided by the Health Officer.
18.07.085 Health Officer review and notice of decision. If. after investigation, the Health Officer
determines that the alternative sewage disposal system application is in accordance with the terms of this
chapter and any regulations issued pursuant thereto. the Health Ofticer shall approve or conditionally approve
the application for an alternative sewage disposal system. ::'uch approval may be made subject to such
conditions as the Health Officer deems necessary to insure compliance with this chapter. and any regulations
issued pursuant thereto.
The Health Officer shall issue a written notice of decision granting, denying or granting with conditions any
application for an alternative sewage disposal system. The notice of decision shall be sent to an applicant by
certified mail and shall inform an applicant of his or her appeal rights. The appeal period shall run from the
mailing date of the notice of decision.
Any such approval shall become null and void under the following circumstances:
A. The work authorized has not been commenced with ie one year after approval, unless an extension of an
additional one year has been granted by the Health Officer;
B. Construction of the approved system has commenced hut s~hsequently abandoned for a continuous
period of ninety days;
P-.".. tf':;'
-- ---- -- . T~ - --
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C. Construction of the approved system is not proceeding in accordance with the terms of approval.
18.Q7.090 Construction Permit. A construction permit is issued after all required siting and design
standards have been found to comply with Section 800, Alternative Systems, of the Regulations for Design,
Construction and Repair of Individual Sewage Disposal Systems.
18.07.095 Certificate of Installation. The certiticate "f installation is issued upon completion of the
construction of the alternative sewage disposal system. Issuance of the certificate of installation does not
authorize operation of the system but acknowledges completion of the construction of the system within the
terms of both the Health Officer approval and the construction permit.
18.07.100 Operating permits. Each alternative sewage disposal system shall have a valid operating permit
to ensure the continued proper maintenance and operation of the system as designed and constructed. An
operating permit is issued after issuance of the certificate of installation. Operating permits are issued for a
period of two years, unless otherwise specified by the Health Officer in accordance with written guidelines
established by the Health Officer. Operating permits shall renewed in accordance with the terms of the permit
or as otherwise specified by the Health Officer. Renewal of an operating permit requires an application, a fee.
and the results of the required system inspection and monitoring demonstrating continued proper maintenance
and operation of the system as designed and constructed. Operating permits must also be renewed at the ume
of property sale or, in the case of commercial pr,;perties. upon change in occupants. Each operating permit
shall include the design wastewater !lows of the system. Certitied copies of operating permits shall be
recorded in the office of the County Recorder of Marin County. Operation of an alternative sewage disposal
system prior to issuance of an operating permit. without a currently valid operating permit, or after revocation
of an operating permit shall be deemed a violation of the provisions of this chapter. Failure to submit a
renewal application, or fee or inspection and monitoring results, or failure to undertake required corrective
measures as specified by the Health Officer may result in non-renewal or revocation of the operating permit.
18.07.105 Waiver/Variance. The Health Ofticer may grant a waiver/variance to any particular requirement
imposed by the regulations for the construction of a new alternative sewage disposal system if slhe determines
that the general purpose of this chapter will be achieved by such waiver/variance. Requests for a
waiver/variance to any requirement of the regulations for the construction of a new alternative sewage disposal
system shall be submitted in writing to the Marili County Community Development Agency, Division of
Environmental Health Services, on forms supplieil by the Health Ofticer. The application shall be
accompanied by fees as specified in the most recendy adopteil resolution of the Board of Supervisors
designating fees for Environmental Health Services Upon determination that the application has been
accepted for filing, a copy of the waiver/variance application shall be transmitted to the Regional Water
Quality Control Board. The Regional Water Quality Control Board shall be requested to comment upon the
waiver/variance application within thirty (30) days unless the 30 day review period is waived by Regional
Water Quality Control Board staff.
The Health Officer shall review the wa;ver/variance ,equest, conduct an investigation and hold a public
hearing in accordance with Section 18.07.107 of this Chapter to determine whether the waiver/variance should
be granted. After conclusion of the investigation anil public hearing, the Health Officer shall prepare a written
order granting or denying the waiver/variance, anil shall include in such written order specific findings of fact
and reasons for its granting or denial. The Health Oflicer may grant a waiver/variance for the construction of
a new alternative sewage disposal system, with or without conditions, only if all of the following findings are
made:
Pd::'~ fI()
-
A. That because of special circumstances applicable to the subject property, including size, shape,
topography, location or surroundings, the strict application of the Regulations for Design, Construction
and Repair of Individual Sewage Disposal Systems is found to deprive the subject property of privileges
enjoyed by other properties in the vicinity;
B. That the granting of the waiver/variance shall not constitute a grant of special privilege inconsistent with
the limitations upon other properties in the vicinity in which the subject property is situated;
C. That the granting of the waiver/variance shall not be detrimental to the general public health, welfare, or
safety of the community;
D. That the granting of the waiver/variance shall not be one of a potential series of waivers/variances that
together may cause an adverse threat to water quality or public health; and
E. That the granting of the waiver/variance shall not result in degradation of the quality of nearby surface
waters or ground waters such that existing or potential benelicial uses of these waters would be adversely
impacted; and
F. That the granting of the waiver/variance is determined to be in substantial compliance with the
Alterr.ati'.'e Sewage Disposal System Reg"lations which have been established by mutual agreement of
the County of Marin and the Regional Water Quality Control Board.
18.07.107 Public Hearings. When a public hearin~ is required on a waiver/variance application, public
notice shall be given and the hearing shall he conducted in compliance with this section.
A. Content of Notice. The publ ic shall be provided notice of hearings in compl iance with State law.
Notice of a public hearing shall include: the date, time and place of the hearing; the name of hearing
authority; a general explanation of the matter to be considered; and a ge~eral description, in text or by
diagram, of the location of the real property that is the subject of the hearing. If a proposed negative
declaration or final environmental impact report has been prepared for the project in compliance with the
County's CEQA guidelines, the hearing notice shall include a statement that the hearing authority will
also consider approval of the proposed negative dechration or certification of the linal environmental
impact report (EIR).
B. Method of Notice Distribution. Notice of a public hearing required by this Chapter for a
waiver/variance or appeal shall be given as follows, as required by Government Code sections 65090 and
65091: (The Health Officer shall chose to comply with either I or 2, and shall comply with 3).
I. Notice shall be published at least once in a local newspaper of general circulation in the County
at least 10 days before the hearing; or
2. Notice shall be posted in at least three public places in the area of the property which is the
subject of the hearing at least 10 days before the hearing: and
3. Notice shall be mailed or delivered at least 10 days before the hearing to:
a. The owner(s) of the property being considered or the owners agent. and the applicant;
n ""
_.__.~ .-...- r- -"
,
~
b. All cwe,' , - 'J d> ,nown on the County's latest equalized assessment roll
within 300 feet of the property which is the subject of the hearing; and
c. Any person who has filed a written request for notice with the Health Officer.
C. Scheduling of Hearing. The matter shall be scheduled for public hearing within 60 days from the date
the completed application was filed and at least thirty (30) days after transmittal of the application to the
Regional Water Quality Control Board unless the 30 day review period is waived by Regional Water
Quality Control Board staff.
D. Hearing Procedure. Hearings shaH be held at the date. time. and place for wh ich notice has been given
as required in this Chapter. Any hearing may be continued provided that before the adjournment or
recess of the hearing, a clear public announcement is made specifying the date, time. and place to which
the hearing will be continued. The hearing shall be informally conducted and the rules of evidence need
not apply. The applicant(s) and real property owners entitled to notice may appear personally, produce
evidence, and have counsel retained at their expense.
E. Notice of Decision - Health Officer. The Health Ofticer shall announce and issue an order of the
decision at the conclusion of a scheduled hearing. or continue the hearing to a specitied date. time and
place at which time the decision will be annoiinct'd. The decision shall contain applicable findings and
any conditions of approval. After the decision is announced, applicant(s) and real property owners
entitled to notice shall be informed of their appeal rights. The time to tile an appeal runs from the date
the Health Officer's decision is announced. Following the heanng. a written notice of tt..: decision and
any conditions of approval shall be mailed to the applicant at the address shown upon the application and
any party requesting it. [n addition. the Notice of Decision shall include a statement that the
waiver/variance granted by the Health Ofticer may require a Waste Discharge Permit from the Regional
Water Quality Control Board.
F. Appeals. In the event that any applicant(s) fa' a waiver/variance and/or any owners of real property as
shown on the County's last equalized assessment roll within 300 feet of the property which is the subject
of the hearing who are entitled to notice are dissatistied with the decision of the Health Officer, said
persons shall have the right to request a hearing betore the Board of Appeals consi"ing of: Health
Services.Public Health Ofticer. the Community Development Agency Director and the Public Works
Director.
Actions or appellate determinations of the Board of Appeals may be appealed to the Board of
Supervisors.
G. Filing Appeals - Board of Appeals. Appeals shal[ be addressed to the appellate body, in writing and
shall state the basis of the appeal. Appeals shall be filed in the Oftice of Environmental Health Services
no later than 4:00 p.m. of the tenth calendar day following the date that the decision of the Health
Officer from which an appeal is taken was announced. Appeals shall be accompanied by the filing fee as
specified in the current resolution of the Board of Supervisors Establishing fees for Environmental
Health Services.
H. Notice of Hearing - Appeals. Notice of the appeal to the Board of Appeals and/or the Board of
Supervisors shall follow the procedures outlined in subsection B,. of this section.
p;\~c f;'i\
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I. Board or Appeals hearing - Time Limit. -'he Board of Appeals shall conduct a hear;r,~ :',: :~t~r ~hall
60 calendar days from the date the appeal was filed. Upon conclusion of the hearing, the Board of
Appeals shall either affirm, modify or revoke the order of the Health Officer. The hearing shall be
informally conducted and the rules of evidence need not apply. The applicant(s) and real property
owners entitled to notice may appear personally, produce evidence, and have counsel retained at their
expense.
The Board of Appeals shall announce the decision at the conclusion of a scheduled hearing, or continue
the hearing to a specified date, time and place at which time the decision will be announced. Following
the hearing, a written notice of the decision and any conditions of approval shall be mailed '0 the
applicant at the address shown upon the application and any party requesting it. In addition, the Notice
of Decision shall include a statement that the waiver/variance granted by the Health Officer may require
a Waste Discharge Permit from the Regional Water Quality Control Board. The time to file an appeal
runs from the date the Board of Appeals' decision is announced.
1. Recording. All hearings before the Board of Appeals shall be tape recorded and such recording shall
become part of the administrative record.
,
K. Board or Supervisors hearing - Time Limit.' Any applicant(s) for a waiver/variance and/or any owners
of real property as shown on the County's last equalized assessment roll within 300 feet of the property
which is the subject of the hearing who are entitled to notice who are dissatisfied with the decision of the
Health Officer may, within ten calendar days after the decision of the Board of Appeals has been
announced, file an appeal with the clerk of the Board of Supervisors who shall present the same at the
next meeting of the Board. The Board of Supervisors shall then set a day for hearing said appeal. The
Board of Supervisors shall determine an appeal no later than its sixth regular meeting following the date
on which the appeal was filed. The action, or appellate determination, from which an appeal is taken
may be reversed or modified only hy the affirmative vote of a majority of the authorized memhership of
the Board.
The hearing shall be informally conducted and the rules of evidence need not apply. The applicant(s)
and real property owners entitled to notice may appear personally. produce evidence, and have counsel
retained at their expense.
The Board of Supervisors shall announce the decision at the conclusion of a scheduled hearing, or
continue the hearing to a specified date, time and place at which time the decision will be announced.
Following the hearing, a written notice of the decision and any conditions of approval shall be mailed to
the applicant at the address shown upon the application. In addition, the Notice of Decision shall
include a statement that the waiver/variance granted by the Health Officer may require a Waste
Discharge Permit from the Regional Water Quality Control Board. The time to file an appeal runs from
the date the Board of Appeals' decision is announced.
L. Failure or the appellate body to act. Failure of the appellate body to act within the time specified shall
sustain the action, or the appellate determination being appealed.
M. Exhaustion or remedy_ All rights of appeal are exhausted when the proceedings set forth herein have
been consummated.
-- 1 - ----- - -
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18.07.110 Permits - Nontransferable. Construction and operating permits issued hereunder for alternative
sewage disposal systems may not be transferred from person to person, or location to location.
18.07.120 Performance Monitoring and Reporting. A monitoring program shall be established individually
for each alternative sewage disposal system at the time a operating permit is issued. Said monitoring shall be
performed to ensure that the alternative sewage disposal system is functioning satisfactorily to protect public
health and safety. Such monitoring report may be amended upon renewal of an operating permit The specific
requirements of the monitoring report shall include recommendations of the system designer along with general
monitoring criteria and monitoring frequency developed by the Health Officer.
A. Monitoring of alternative sewage disposal systems shall ~e conducted by or under the supervision of
either a registered civil engineer or registered environmental health special ist.
B. The County shall conduct spot-check inspections of alternative sewage disposal systems on their own and
may also be present to observe the performance of monitoring activities by others.
C. Monitoring results shall be submitted to the Health Officer annually, by July 1st, for the preceding 12
month period beginning June 1st and ending May 31st. Monitoring results shall be reported on a
standard form supplied by the Health Officer. The monitoring report shall be signed by the Registered
Civil Engineer or Registered Environmental Health Specialist responsible for the monitoring.
Notwithstanding the annual report, the County shall be notitied immediately of any system problems
observed during the inspection and monitoring or at any other time.
18.07.130 Abandoned alternative sewage disposal systems. Any alternative sewage disposal system which
has been discontinued from further use, or to which no waste or soil pipe from plumbing fixture(s) is
connected, shall be abandoned pursuant to procedures specified by the Health Officer. Abandonment of
sewage disposal facilities shall require submission of applicable fee and application. An inspection is required
upon completion of the abandonment.
18.07.140 Permits - Revocation. The Health Officer may revoke any permit issued hereunder if s/he
determines that the permittee is acting in contravention of the provisions of this chapter or the conditions of the
permit.
Upon reasonable suspicion by the Health Ofticer that the conditions in or around the alternative sewage
disposal system may pose a serious and imminent threat to public health or water quality, a temporary
suspension of the operating permit may be ordered. Such suspension shall be followed within three (3) days
by written notice of the action mailed to the permittee, setting a time for a written response within ten (10)
days of the date of mail ing of the written notice. At that time, the Health Officer shall determine whether
there is cause to revoke the operating permit. Upon finding of cause, the Health Officer shall issue a written
notice of decision revoking the operating permit for an alternative sewage disposal system. The notice of
decision shall be sent to the applicant by certitied mail and shall inform an applicant of his or her appeal
rights. The appeal period shall run from the mailing date of the notice of decision.
Failure to permit further inquiry into the condition of the alternative sewage disposal system including access
to the system site, shall be sufficient cause to revoke the permit. A revoked permit may be reinstated if the
health officer determines that a plan has been estahlished for adequate repair, alteration and/or maintenance of
the system, and all costs of enforcement. including attorney fees. p,rmit fees and any other applicable costs
determined by the Health Officer as heing incurred. have been paid.
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18.07.150 Abatement. In any action, judicial or administrative, to enforce any provision of this Title relating
to an individual alternative sewage disposal system. the County may recover all of its costs of enforcement,
including, but not limited to, any administrative overhead, salaries and expenses incurred by the following
County departments: Community Development Agency, Environmental Health Services Division, County
Counsel and District Attorney. All such costs shall be become a lien upon the property upon which the system
is located.
18.07.160 Enforcement. It shall be the duty of the county Health Officer to enforce the provisions of this
chapter and the regulations issued thereunder. S/he may enter any premises during normal business hours,
with the owner's consent, to inspect the individual sewage disposal system to determine if it is functioning
satisfactoril y. In circumstances where the Health Officer has not been granted an access easement and the
owner's consent has not been obtained, the Health Officer shall first obtain an inspection warrant pursuant to
applicable law absent exigent circumstances. Exigent circumstances exist when the Health Officer or his or
her duly authorized agent determines that an imminent public health emergency exists which requires
immediate action.
In cases as determined by the Health Ofticer to be of an imminent public health emergency, including but not
limited to, system failure or surfacing sewage,-,emergency provisions may be instituted to abate such
emergency. Provisions to abate an imminent public health emergency shall include, but not be limited to
shutting off vf water, vacating of premises or illstallarion of temporary holding tanks.
18.07.170 Appeals.
A. Administrative actions appealable. In the event that any applicant for a permit or any permittee
(hereinafter known as appellant) is for any reason dissatisfied with the actions of the Health Officer by
reason of failure to grant a permit. revocation of a permit. or imposition of any conditions relating to
said permit, said appellant shall have the right to request a hearing before a Board of Appeals consisting
of: the Health Services-Public Health Ofticer. the Community Development Agency Director and the
Public Works Director.
Actions or appellate determinations of the Board of Appeals may be appealed to the Board of
Supervisors.
B. Filing Appeals - Board or" Appeals. Appeals shall be addressed to the appellate body in writing and
shall state the basis of the appeal. Appeals shall be tiled in the office of Environmental Health Services
no later than 4:00 p.m. of the tenth calendar day following tbe date that the decision of the Health
Officer from which an appeal is taken was mailed to the appellant. Appeals shall be accompanied by the
filing fee as specified in the current resolution of the Board of Supervisors establishing fees for
Environmental Health Services.
C. Board of Appeals hearing - Time Limit. The Board of Appeals shall conduct a hearing no later than
30 calendar days from the date the appeal was tiled. The appellant shall be notified of the hearing date
in a timel y manner. Upon conclusion of the hearing, the Board of Appeals shall either affirm, modify
or revoke the order of the Health ofticer. The hearing shall be informally conducted and the rules of
evidence need not apply. The appellants may 1ppear personally. produce evidence, and have counsel
retained at their expense.
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The Board of Appeals shall announce the decision at the conclusion of a scheduled hearing, or continue
the hearing to a specified date, time and place at which time the decision will be announced. Following
the hearing, a written notice of the decision and any conditions of approval shall be mailed to the
applicant at the address shown upon the application and any party requesting it. In addition, the Notice
of Decision shall include a statement by the Health Officer that a Waste Discharge Permit may be
required from the Regional Water Quality Control Board. The time to file an appeal runs from the date
the Board of Appeals' decision is announced,
D. Recording. All hearings before the Board of Appeals shall be tape recorded and such recording shall
become part of the administrative record.
E. Board or Supervisors Hearing - Time Limit. Any appellant may, within ten calendar days after the
decision of the Board of Appeals has been announced, file an appeal with the clerk of the Board of
Supervisors who shall present the same at the next meeting of the Board. The Board of Supervisors shall
then set a day for hearing said appeal. The Board of Supervisors shall determine an appeal no later than
its sixth regular meeting following the date on which the appeal was filed. The action, or appellate
determination, from which an appeal is taken may be reversed or moditied only by the affirmative vote
of a majority of the authorized membership of the Board.
The hearing shall be informally conducted and the rules of evidence need not apply. The applicant(s)
and real property owners entitled to notice may appear personally. produce evidence, and have counsel
retained at their expense.
The Board of Supervisors shall announce the decision at the conclusion of a scheduled hearing, or
continue the hearing to a specified date, time and place at which time the decision will be announced.
Following the hearing, a written notice of the decision and any conditions of approval shall be mailed to
the applicant at the address shown upon the application and any party requesting it. In addition, the
Notice of Decision shall include a statement by the Health Omcer that a Waste Discharge Permit may be
required from the Regional Water Qual ity Control Board. The time to file an appeal runs from the date
the Board of Appeals' decision is announced.
F. Failure or the appellate body to act. Failure of the appellate hody to act within the time specified shall
sustain the action, or the appellate determination being appealed
G. Exhaustion or remedy. All rights of appeal are exhausted when the proceedings set forth herein have
been consu mmated.
18.07.180 Penalty ror violations. Any person violating any of the provisions of this chapter is guilty of a
misdemeanor and, upon conviction thereof, shall be punished by a fine of not more than one thousand dollars,
or by imprisonment. Such person is guilty of a separate offense for each and every day during any portion of
which a violation of this chapter is committed, or permitted by such person.
18,07.190 Severability. If any section, subsection, subdivision, sentence, clause or phrase of this chapter is,
for any reason, held to be illegal or unconstitutional, such decision shall not affect the validity of the remaining
portions of this chapter. The Board of Supervisors (Iedares that they would have passed this chapter and each
section, subsection, subdivision, sentence. clause or phrase thereof, irrespective of the fact that anyone or
more sections, subsections, subdivisions. sentences. clauses or phrase~ are declared illegal or unconstitutional.
P;tg~ #12
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SECTION III: EFFECTIVE DATE AND PUBLICATION
This Ordinance shall be, and is hereby declared to be, in full force and effect on September 5, 1996, and sha..
be published once before the expiration of fifteen (15) days after its passage, with the names of the Supervisors
voting for and against the same, in'the Marin independent Journal, a newspaper of general circulation
published in the County of Marin.
SECTION IV: VOTE
PASSED AND ADOPTED at the regular meeting of the Board of Supervisors of the County of Marir, State
of California, on the 6th day of August, 1996, by the following vote to-wit:
AYES: Supervisors: Harry 1. Moore, Gary Giacomini, Harold C. Brown, Jr.
NOES: Supervisors: None
ABSENT: Supervisors: Ann~lte Rose. John B. Kress
0j{~/ ~ }-
HAROtD C. BROWN, JR. CHAIR~N
MARIN COUNTY BOARD OF SUPERVISORS
A TIEST:
~
.. .-
artm 1. N Icbols
Clerk of the Board
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P'l"'" d!1
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Regulations for Alternative Sewage Disposal
Systems adopted pursuant to Section 18.07.060..
of the Marin County Code.
SECTION 800
ALTERNATIVE. SYSTEMS
801 - General provisions
A. Alternative sewage disposal systems may be permitted by
the Health Officer on individual lots where: (a) it is
determined that sewage cannot be disposed of in a sanitary
manner by a standard septic tank - drainfield system; or,
(b) the health officer finds that an alternative system
will protect the public health in a manner at least equal
to that of the utilization of a standard system. Such
alternative systems must comply with the specific
requirements set forth in this section.
B. Alternative systems may be. 'used to serve individual single
family residences, mUlti-family residential structures,
commercial establishments, and institutional and
industrial facilities.
c. Alternative systems may be approved for use in county-
established moratorium areas, Regional Water Quality
Control Board (Regional Board) individual system
prohibition areas, or areas affected by cease and desist
orders which include prohibitions or limitations on new
connections to a community sewer system. Such use may
only be permitted with the approval of the Regional Board.
D. Types of alternative systems shall be categorized and
their application shall be governed by the following:
1. Category 1 - Repairs. This category includes all
viable alternative systems that have technical
merit, but not necessarily documented performance
history. Alternative systems in this category may
be used for system repair only.
2. Category 2 - New Construction. This category
includes alternative systems that have substantial
documented performance history under conditions
representative of the proposed application, and for
which the county has adopted specific technical
standards that are incorporated in this section.
Alternative systems in this category may be used
for new construction on any parcel legally created
prior to the adoption of these Regulations as well
as for repair of existing systems.ì
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3. Category 3 - Subdivisions. This category is
restricted to alternative systems that have
sufficient successful documented performance
history and operating experience to allow them to
be used for creation of new lots, and are so
designated in this section. Category 3 alternative
systems may also be used for repair of existing
systems and for new construction on existing lots.
E. All alternative systems shall be installed by a licensed
contractor.
F. Notwithstanding any other provisions of these Regulations,
final approval of alternative system proposals shall be at
the discretion of the Health Officer.
802 - Construction Permit and Review Reauirements
..
A. Engineering plans and site data for alternative systems
shall be submitted in accordance with standard sewage
disposal application procedures outlined in Section 100 of
these Regulations.
B. site evaluations, including soil profile inspection and
percolation testing, shall be conducted in accordance with
standard procedures outlined in Section 500 of these
Regulations.
C. Engineering plans for alternative systems shall be signed
by a Registered Civil Engineer or Registered Environmental
Health Specialist who is knowledgeable and experienced in
the field of on-site sewage disposal. The designer shall
also be responsible for inspection of system installation
to assure conformance with approved plans, and shall
provide an "As-Built" drawing of the installation to the
County and property owner. The construction inspection by
the designer shall be in addition to standard County
inspection work carried out in accordance with provisions
of Section 703 of these Regulations.
D. In addition to site data and supporting engineering
calculations, alternative system applications shall
include:
1- Contingency plan which outlines specific actions to
be taken to repair, expand or replace the system,
should the need arise.
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2. Construction inspection schedule which identifies
critical points during construction at which time
inspections will be made by the system designer.
3. operation, maintenance and monitoring instruction
which provide brief and simple guidelines to the
system owner(s) regarding the operation of the
system, his/her responsibilities and system
monitoring needs.
4. Grant easement authorizing access by the Health
Officer, Regional Water Quality Control Board
personnel and agents for .periodic inspection of
system operation.
E. Engineering plans will be reviewed by the Health Officer
and, as appropriate, Regional Board and external civil
engineering consultant(s) yelected by the Health Officer.
At a minimum, the Regional Board will be notified of all
proposals for the use of alternative systems for: (a)
large systems (flows of 1,500 gpd, or more); (b)
subdivisions; and, (c) cases where cumulative impacts are
of special concern.
F. Permits issued for alternative systems will expire if
building construction is not started within a period of
one year. Applicants may submit a written request for an
extension of this limit. Such a request may be granted in
writing based on the judgment of the Health Officer that
delay in construction is a result of weather conditions or
other unavoidable circumstances.
G. Applications for an alternative systems shall be accompanied
by application fees. The amount of the fees shall be
established by the Board of Supervisors by ordinance and
shall reflect the cost to the county of reviewing, approving
and enforcing alternative system permits under these
regulations. These regulations shall not be operative until
fees are established.
803 - Ooeratinq Permits
A. In addition to a construction permit, an operating permit
is required for all alternative systems, with the
exception of those installed solely for the repair of
existing systems for single family residences. The Health
Officer reserves the right to require an operating permit
for repair systems where, in his/her judgement, such a
permit is necessary to assure protection of water quality
and public health. Also, an operating permit will be
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required for any repair utilizing a new alternative system
which is not classified as a Category 2 or J system; these
cases will require Regional Board review. The operating
permit provisions outlined in this section also apply to
any standard systems requiring operating permits, as
determined by the Health Officer.
B. Operating permits shall be issued by the Health Officer at
the time of initial construction of the system; and they
are required to be renewed at least every two years or as
otherwise specified by the Health Officer on a case-by-
case basis. The Health Officer may reduce the renewal
frequency 'to' once every three or four years after
successful performance is demonstrated; also, annual
renewal may be required for certain types of systems or
situations as deemed necessary by the Health Officer.
Operating permits must also be renewed at the time of sale
or, in the case of commergial properties, upon change of
occupants.
C. Operating permits are intended to serve as the basis for
verifying the adequacy of alternative system performance
and maintenance. Permit conditions shall include
monitoring and inspection requirements, permit duration,
and other provisions deemed appropriate by the Health
Officer.
D. Renewal of an operating permit requires the submission of
an application, a fee, and the results of required system
inspection and monitoring (per Section 804 below).
E. Failure to submit a renewal application, the required fee
or specified monitoring and inspection data, or failure to
undertake any required corrective work specified by the
Health Officer may be cause for non-renewal or revocation
of the operating permit by the Health Officer.
F. Certified copies of operating permits and notices of
withdrawal 'of operating-permits, ,"when issued, will be
recorded in the office of the County Recorder of Marin
County.
804 - Performance Monitorinq and Reoortinq
A. A monitoring program will be established individually for
each alternative system at the time of issuance of the
operating permit; it may be amended at the time of permit
renewal. Said monitoring shall be performed to ensure
that the alternative system is functioning satisfactorily
to protect public health and safety. The specific
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requirements will incorporate recommendations of the
system designer along with general monitoring criteria
developed by the Health Officer.
B. Monitoring requirements will vary depending upon the
specific type of alternative system; but, in general, they
will include the following:
l. Recording of wastewater flow based on water meter
readings, pump event counters, elapsed time meters
or other approved methods;
2. Inspection and recording of.."water levels in
monitoring wells in the disposal field;
3. Water quality testing of selected water samples
taken from points in the treatment process, from
monitoring wells, or from surface streams or
drainages; typical water quality parameters to be
analyzed for may include total and fecal coliform,
nitrate, biochemical oxygen demand (BOD) , and
suspended solids;
4. Inspection and observation of pump operation or
other mechanical equipment; and,
5. General inspection of treatment and disposal area
for evidence of seepage, effluent surfacing,
erosion or other indicators of system malfunction.
c. The required frequency of monitoring for each installation
will generally be in accordance with the following
schedule, assuming a record of suitable performance is
established:
. Years 1 and 2 of operation - quarterly monitoring
. Years 3 and 4 of operation - semi-annual monitoring
. Years 5 and beyond - annual monitoring
Monitoring frequency may be increased if system problems
are experienced. Monitoring frequency for each system or
type of system will be established be the Health Officer.
D. Monitoring of alternative systems shall be conducted by or
under the supervision of one of the following:
l. Registered civil Engineer.
2. Registered Environmental Health Specialist.
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The County shall conduct spot-check inspections of
alternative systems on their own and may also be present
to observe the performance of monitoring activities by
others. The County will ordinarily inspect about 20
percent of the alternative systems in a given year.
County inspections will be made as a quality control check
and to assure County staff maintain personal familiarity
with the operation of various types of alternative systems
approved for use in the County. Additionally, the Health
Officer reserves the right to require, on a case-by-case
basis, "third party" or County inspection and monitoring
of any alternative system where deemed necessary because
of the complexity .of the system. or. the sensitive nature of
the site.
E. Monitoring results shall be submitted to the Health
Officer annually, by July 1st, for the preceding 12-month
period ending on May 31st. ,. Monitoring results shall be
reported on a standard form supplied by the Health
Officer. The monitoring report shall be signed by the
Registered civil Engineer or Registered Environmental
Health Specialist responsible for the monitoring.
Notwithstanding the annual report, the County shall be
notified immediately of any significant system problems
observed during the inspection and monitoring or at any
other time.
F. The Health Officer will compile all monitoring and
inspection results annually and submit them to the San
Francisco Regional Water Quality Control Board, along with
appropriate summaries and discussion of special problems
or issues. This report shall be prepared and submitted by
October 1st of each year for the preceding June 1st - May
31st monitoring year results.
G. In evaluating the performance of alternative systems, the
Health Officer shall take into account such factors as:
. effluent quality from treatment units;
. wastewater acceptance rates within treatment units
(e.g., sand filter beds) and disposal fields (e.g. ,
sand trenches and mound beds);
. effluent surfacing or near-surface soil saturation;
. groundwater mounding;
. groundwater quality effects beneath and downgradient I
I
of the disposal system (e.g. , bacteriological,
nitrate, other); and,
. equipment malfunctions.
805 - Svstem Evaluation and Adootion of Standards
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A. An annual performance review of alternative systems shall
be made by the Health Officer. Technical evaluation of
system performance shall be based primarily on monitoring
results and shall consider the following:
1.. Actual system usage in relation to design sewage
flow;
2. Effluent level fluctuations in monitoring wells and
evidence of seepage;
3. Groundwater and surface water quality impacts;
4. Influence of climatic conditions;
5. Operation of mechanical and electrical equipment;
and,
6. Other pertinent findings.
B. The results of the Health Officer's annual evaluation of
alternative systems may serve as the basis for adopting or
modifying siting and design criteria for specific types of
alternative systems. Recommendations may also be made by
the Health Officer concerning permitting, review or
monitoring requirements, or other issues as appropriate.
Any changes in criteria or procedures shall be submitted
to the Regional Board for their review and concurrence.
C. As sufficient experience and data are obtained, Category 2
systems will be reviewed to determine the appropriateness
of elevating the particular system to Category 3. A
minimum of two to four years of successful operation would
normally be expected to be demonstrated prior to elevating
alternative systems from Category 2 to Category 3.
Determination and recommendations regarding reclassifying
alternative systems will be made by the Health Officer
based on direct field experience and considering input
from:
l. San Francisco Bay Regional Water Quality Control
Board.
2. Local engineering community.
3. Local contractors.
4. Users and other affected parties.
5. External technical consultants and manufacturers,
as appropriate.
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6. Experience from other jurisdictions.
Written approval from the Regional Board Executive Officer
is needed for elevation of any given type of alternative
system from Category 2 to Category 3.
D. Proposals to add new alternative systems to Category 2
will be received and reviewed annually by the Health
Officer. The required procedures are as follows:
1. Proposals must be received by December 31st for
consideration in the following calendar year.
2. Proposals shall be accompanied by a fee established
by the County to cover County review and
administrative costs.
3. Proposals shall set forth siting and design
criteria in a format.~uitable for direct
incorporation in these Regulations and consistent
with that for existing alternative systems covered
by these Regulations.
4. Proposals shall include supporting data and
discussion of the rationale for the proposed
alternative, and for all recommended siting and
design standards.
5. Following internal review, the Health Officer will
circulate the proposal for review by the local
engineering community and will organize at least
one workshop-meeting for discussion of the
proposal.
6. If, in the judgement of the Health Officer, and
based on input from the local engineering
community, the proposal merits further
consideration, the Health Officer will submit the
propos:al.to the San Francisco. .Bay Regional Water
Quality Control Board (Regional Board) for review.
The Health Officer will submit pending proposals to
the Regional Board by July 1st of each year.
7. Siting and design standards for the alternative
system will be incorporated into these Regulations
following acceptance by the Health Officer and
written approval from the Executive Officer of the
Regional Water Quality Control Board.
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806 - TYPes of Alternative Svstems Permitted
A. category 1 - Repairs. Alternative systems permitted to be
used for the repair of existing systems include systems
listed in categories 2 and 3 below and all other
reasonably viable alternatives that have technical merit,
but not necessarily documented performance history. For
systems other than Category 2 and 3 alternatives, the
system designer shall furnish engineering rationale,
including appropriate references, to substantiate the
design source and applicability of the proposed system.
Proposals that include designs that cannot be
substantiated.bysuitable reference materials or field
performance results will be classified as experimental
research proposals and, as such, will not be permitted
under these Regulations. The Health Officer reserves the
right to establish special operating permit requirements
for Category 1 systems as Jeemed necessary for protection
of public health.
B. category 2 - New construction. Alternative systems
permitted to be used for new construction on any existing
lot of record include the following, plus systems listed
under Category 3 below.
. Pressure-Dosed Sand Trenches
. Intermittent Sand Filters
. Steep Slope Mounds
Limits on the number of each type of Category 2
alternative system that may be permitted shall be
established in a Memorandum of Understanding (M.O.U.)
between the Health Officer and the Executive Officer of
the San Francisco Bay Regional Water Quality Control
Board. These limits may be adjusted from time-to-time
upon mutual agreement between the Health Officer and the
Executive Officer.
C. Category 3..,.cSubdivisions. Alternative systems permitted
to be used for the creation of new lots include the
following:
. Standard Mounds
807 - Cumulative Impact Assessment
A. General Provisions. In addition to meeting established
siting and design criteria, proposals to use alternative
systems must, in accordance with Paragraph D of this
Section, also provide an assessment of potential
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cumulative impacts that could result from the installation
of the alternative system(s). Such cumulative impact
assessment shall be conducted in accordance with the
requirements outlined in this section. The results of the
assessment shall be submitted for review by the Health
Officer and may be grounds for denial or revision of the
alternative system proposal, regardless of compliance with
other siting and design criteria.
B. CUmulative Impact Issues. Where required, the primary
issues to be addressed in cumulative impact assessments
include the following:
1. Groundwater Mounding. A rise in the water table,
referred to as "groundwater mounding", may occur
beneath or downgradient of sewage disposal systems
as a result of the concentrated hydraulic loading
from one or more systems in a given area.
2. Groundwater Nitrate Loading. Discharges from on-
site sewage disposal systems contain high
concentrations of nitrogen that may contribute to
rises in the nitrate level of local and regional
aquifers.
For individual cases, the Health Officer may identify and
require analysis of cumulative impact issues other than
those listed above which, in his/her judgement could pose
potential pUblic health or safety risks.
C. Qualifications. Cumulative impact assessments required
for alternative system proposals shall be performed by or
under the supervision of one of the following licensed
professionals:
1. Registered civil Engineer
2. Registered Geologist
3. Certified .Engineering Geologist
4. Registered:Environmental:Hea'l.th" Specialist
Additionally, the licensed professional assuming
responsibility for the cumulative impact assessment shall
have training and experience in the fields of water
quality and hydrology.
D. Cases Requiring Cumulative Impact Assessment. Cases where
cumulative impact assessments shall be required are listed
in Table 8-1, according to the type of installation, the
type of alternative system and the type of cumulative
impact issue of concern. Additionally, the Health Officer
reserves the right to require the completion of a
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cumulative impact analysis in any case where, in his/her
opinion, special circumstances related to the size, type,
or location of the alternative system (or systems) warrant
such analysis.
E. Methods
L Groundwater Mounding Analysis
a. Analysis of groundwater mounding effects shall
be conducted using accepted principals of
groundwater hydraulics. The specific
methodology shall be described and supported
with accompanying literature references, as
appropriate.
b. Assumptions and data used for the groundwater
mounding analysis ,shall be stated, along with
supporting information. A map of the project
siting showing the location and dimensions of
the proposed system(s) and the location of
other nearby septic systems, wells and
relevant hydrogeologic features (e.g., site
topography, streams, drainage channels,
subsurface drains, etc. ) shall be provided.
c. The wastewater flow used for groundwater
mounding analyses shall be as follows:
(1) For individual residential systems: 100
gpd/bedroom.
(2) For mUlti-family and other non-residential
systems: design sewage flow.
d. Groundwater mounding analyses shall be used to
predict the highest rise of the water table
and shall account for background groundwater
conditions during the wet weather season.
e. All relevant calculations necessary for
reviewing the groundwater mounding analysis
shall accompany the submittal.
f. Any measures proposed to mitigate or reduce
the groundwater mounding effects shall be
presented and described as to their documented
effectiveness elsewhere, special maintenance
or monitoring requirements or other relevant
factors.
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2. Nitrate Leading
a. Analysis of nitrate loading effects shall, at
a minimum be based upon construction of an
annual chemical-water mass balance. The
specific methodology shall be described and
supported with accompany literature references
as appropriate.
b. Assumptions and data for the mass balance
analysis shall be stated, along with
supporting information. Such supporting
information should include, at a minimum:
(1) climatic data;
(2) groundwater occ~rrence, depth and flow
direction(s);
(3) background groundwater quality data, if
available;
(4) soils and runoff conditions;
(5) wastewater characteristics (i.e. , flow and
sewage strength); and,
(6) other significant nitrogen sources.
c. A map of the project siting showing the
location and dimensions of the proposed
system(s) and the location of other nearby
septic systems, wells and relevant
hydrogeologic features (e.g., site topography,
streams, drainage channels, subsurface drains,
etc.) shall be provided.
d. The wastewater 'flow.. used "forni trate loading
analyses shall be as follows:
(1) For individual residential systems: 100
gpd/bedroom.
(2) For multi-family residential systems and
other non-residential systems: Average
wastewater flow for the system; supporting
data or other basis for the average flow
determinations shall be provided.
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e. Minimum values used for the total nitrogen
concentration of septic tank effluent shall be
as follows:
(1) Residential wastewater: 40 mg/l (for
average flow conditions)
(2) Non-residential wastewater: as determined
from sampling of comparable system(s) or
from literature values.
The Health Officer may require the use of more
conservative values than ,cited above if, in
his/her opinion, the values are not likely to be
representative of the proposed system(s).
f. All relevant calculations necessary for
reviewing the nit;ate loading analysis shall
accomp~ny the submittal.
g. Any measures proposed to mitigate or reduce
the nitrate loading effects shall be presented
and described as to their documented
effectiveness elsewhere, special maintenance
or monitoring requirements or other relevant
factors.
F. Evaluation criteria
1- Groundwater Mounding. The maximum acceptable rise
of the water table for short periods of time during
the wet weather season, as estimated from
groundwater mounding analyses, shall be as follows:
a. Mound Systems.
(1) For Level sites (0 - 2% Slope). The
seasonal water table shall not rise closer
than 12 .inches from the c' bottom of the sand
fill for mounds having a sand fill depth of
12 inches. If the sand fill depth is 24
inches or the mound is preceded by an
intermittent sand filter, the seasonal
water table shall not rise closer than 6
inches from the bottom of the sand fill.
Also, the Health Officer reserves the right
to require, in individual cases, up to 24
inches of groundwater clearance where
deemed necessary for protection of public
health.
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-
,
(2) For sloping sites (> 2% Slope). The
seasonal water table shall not rise closer
than 12 inches to ground surface at the
downslope toe of the mound.
b. Pressure-Dosed Sand Trenches and Intermittent
Sand Filters. Groundwater mounding beneath the
drainfield shall not result in more than a 50-
percent reduction in the minimum depth to
seasonally high groundwater as specified in
Tables PDST-l and SF-l.
c. ,Large >systems. Notwithstanding a and b above,
for all alternative systems with design flows
of 1,500 gpd or more (Le. , "large systems"),
the groundwater mounding analysis shall
demonstrate that a minimum groundwater
clearance of 24 inches will be maintained
beneath the system.
2. Nitrate Loading. criteria for evaluating the
cumulative nitrate loading of alternative systems
shall be as follows:
a. For Areas Served by Water Wells.
(1) Alternative systems, on existing lots or
SUb-divisions, shall not cause the
groundwater nitrate-nitrogen concentration
to exceed 7.5 mg/l (as N) at the nearest
existing or potential point of groundwater
withdrawal.
and
(2) The total loading of nitrate from new sub-
divisions shall not result in an average
groundwater nitrate-nitrogen concentration,
;f'<over'the geographical extent of the sub-
division, that exceeds 7.5 mg/l (as N).
b. For Areas Not Served By Water Wells.
(1) Alternative systems, on existing lots or
sub-divisions, shall not cause the
groundwater nitrate-nitrogen concentration
to exceed 10.0 mg/l (as N) at the nearest
existing or potential point of groundwater
withdrawal.
and
8 - 14
---~- .--.._-- --~- ~--_._-- ------ -
-
(2) The total loading of nitrate from new sub-
divisions shall not result in an average
groundwater nitrate-nitrogen concentration,
over the geographical extent of the sub-
division, that exceeds 10 mg/l (as N).
808 - sitina and Desian criteria
Siting and design criteria for Category 2 and Category 3
alternative systems are set forth in Appendix A.
:r
8 - 15
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--
APPENDIX A
~l-
SITING AND DESIGN CRITERIA
FOR
ALTERNATIVE SYSTEMS
r.. SITING AND DESIGN CRITERIA
FOR
STANDARD MOUND SYSTEMS
(CATEGORY 3 SYSTEM)
A. Problems Addressed:
L High groundwater;
2. Shallow soil over fractured rock or coarse alluvium;
-
3. Shallow soil over impermeable soil or bedrock; and,
4. Slow percolation at standard leachfield depths.
B. site criteria:
1. Setbacks. Horizontal setbacks for mound systems
shall be the same as standard drainfield requirements
contained in section 400 of these Regulations.
2. Depth to Groundwater. Minimum depth to seasonal high
groundwater is 2 feet below ground surface.
3. Soil Depth. Minimum depth of soil over bedrock or an
impermeable soil layer shall be 2 to 3 feet,
depending upon ground slope, percolation rate, and
linear loading rate per Tables M-2 through M-4.
4. Depth to Fractured Rock. Minimum depth of soil over
fractured, permeable bedrock shall be 2 feet.
s. Percolation Rate. Percolation rate for mound systems
shall be within the range of 1 to 120 minutes per
inch (MPI) , as determined from testing at 1 to 2 feet
depth.
6. Slope. Maximum ground slope for mound systems is as
follows:
a. for soils having a percolation rate of 1 to 60
MPI: 12%
b. for soils having a percolation rate of 61 to 120
MPI: 6%
7. Reserve Area. A reserve area having suitable site
conditions and sufficient area for full, 100%
replacement of the primary mound shall be provided or
a complete;dual"primary and-secondary mound system
shall be initially installed. In determining the
required space for the reserve or secondary mound,
the required basal area (per Cab) of the primary and
secondary mound shall not overlap. For mounds
positioned end-to-end the surplus sand run-out and
soil fill may overlap if installed as a dual system.
Otherwise, the surplus sand run-out may not overlap.
For mounds positioned upslope/downslope of one
another, the surplus sand run-out may overlap if the
primary and secondary mounds are both installed as a
dual system; otherwise the sand run-out from the
A - 2
-~..._---.-_._- -_.~-
~
upslope mound may not overlap the sand of the
downslope mound.
c. Design Criteria:
L Pretreatment. The mound system shall be preceded by
a septic tank sized for the projected system sewage
flow in accordance with section 602 of these
Regulations.
2. Design sewage Flow. The mound system shall be
designed on the basis of the estimated sewage flow,
determined :in,.accordance with-::Section 601 of these
Regulations, subject to the following exceptions
pertaining to water conservation design reductions:
a. Up to 30-percent reduction in the design sewage
flow and mound system sizing is permissible for:
"
(1) existing lots of record; and,
(2) where a dual mound system is installed or
an intermittent sand filter is included for
treatment prior to discharge to the mound
system.
b. No water conservation-based reduction in mound
system sizing shall be permitted for creation of
new lots.
3. Pressure Dosing. septic tank effluent shall be
applied to the mound system by pressure dosing,
utilizing either an automatic dosing siphon or pump
system. The pressure distribution system shall be
designed in accordance with accepted engineering
practices to achieve, at a minimum:
a. Relatively uniform dosing of septic tank effluent
over the surface application area of the mound
distribution bed;
b. Adequate flow rate, screening of effluent and
suitable piping network to preclude solids
accumulation in the pipes or clogging of discharge
orifices;
c. Suitable access provisions for inspection, testing
and adjustment of the pressure distribution system;
d. Dosing volume to achieve 3 to 5 doses per day at
design flow conditions; and,
A - 3
-
e. At least one distribution lateral for every 36
inches of bed width.
f. The pressure line to the mound shall be buried at
least 18 inches below grade.
4. Sand Fill.
a. Sand specifications. The sand media shall be a
medium to coarse sand which meets the following
gradation specifications:
sieve Size Percent passinq
3/8 100
#4 90 - 100
Uo 62 - 100
U6 45 - 82
#30 25 - 55
#50 5 - 20
#60 o - 10
UOO o - 4
b. Sand Depth. The minimum depth of sand fill, below
the gravel distribution bed, shall be 12 inches.
The minimum depth of sand fill shall be increased
to 24 inches for sites where all of the following
conditions exist:
(1) Percolation rates are faster than 10 MPI;
(2) Groundwater immediately beneath the mound
is hydraulically connected to a definable
aquifer; and,
(3) Groundwater in the immediate project area
is an existing or potential domestic water
source.
c. Lateral Dimensions. The sand shall be placed as
a continuous, fill extending in lateral
dimensions as necessary to meet the following
minimum requirements:
(1) Top of the sand fill shall extend
horizontally beyond the gravel distribution
bed:
. 1 foot in the upslope direction
. 2 feet in the downslope direction
. 2 feet in the longitudinal (side) direction
A - 4
-..--.-- -- -
~
(2) Maximum slope of the top of the sand
surface shall be 3 horizontal to 1
vertical.
(3) Bottom of the sand fill shall be large
enough to meet minimum mound sizing
requirements based upon basal area and
linear loading rate criteria per C.8.b
below.
5. Gravel Distribution Bed
a. Material... The. distribution.bed,shall consist of
3/8-inch washed pea gravel, free of fines.
b. Depth. Pea gravel shall extend a minimum of 6
inches below the invert and 2 inches above the top
of the distribution piping.
c. width. Maximum width of the distribution bed
shall be 10 feet. If a variance from this
criterion is proposed, it must be supported by
detailed groundwater mounding analysis carried out
in accordance with guidelines contained in section
807 of these Regulations.
d. Level. The bottom of the distribution bed shall
be level; and the downslope side shall be parallel
to the slope contour.
6. silt Barrier. The gravel distribution bed shall be
covered in its entirety with a geotextile ("filter
fabric" ) silt barrier. Filter fabric shall be either
polyester, nylon or polypropylene, or any combination
thereof, and shall be suitable for underdrain
applications. Filter fabric shall be non-woven,
shall not act as a wicking agent and shall be
permeable.
7. Soil Cover.
a. Material. A continuous soil cover shall be placed
over the entire distribution bed and sand fill.
The soil cover shall consist of a medium, loamy-
textured soil.
b. Depth. Soil cover depth shall be a minimum of 12
inches and a maximum of 18 inches over the top of
the distribution bed. Soil cover over the
distribution bed shall be crowned to promote
rainfall runoff.
A - 5
-
c. Lateral Extension. The soil cover shall extend a
minimum of 3 feet beyond the perimeter edge of the
sand fill in all directions.
8. Wastewater Loading Rate. The wastewater loading
rates used for sizing the surface area of the
distribution bed and the basal area of the sand fill
shall be as follows:
a. Distribution Bed.
(1) 1.2 gpd/ft2 for individual residential
'septic . systems . .
(2) 1.0 gpd/ft2 for commercial, industrial,
institutional and multi-residential septic
systems.
Reduction in the above wastewater loading rates or
other provisions to insure the long-term integrity
and performance of the mound distribution bed may
be required for high strength waste flows, such as
from restaurants.
b. Sand Basal Area. The basal area of the sand fill
shall be sized to meet maximum basal loading and
linear loading requirements as follows:
( 1) Basal Loading Rates.
. Effective Application Area.
- For level sites (0 - 2% slope) the
effective basal application area
includes the entire sand fill basal
area.
- For sloping sites (>2% slope) the
effective basal application area
includes the sand basal area
immediately below and directly
downslope (at right angles to the
natural slope contours) of the
distribution bed.
. Wastewater Flow. The wastewater flow
used for determining the basal loading
rate shall be the design sewage flow for
the system (e.g., 150 gpd/bedroom for
standard residential system).
A - 6
-_.~._.- - ~
-
. Loading Rates. The maximum basal
loading rate shall be based upon the
demonstrated percolation rate of. the
upper 12 to 24 inches of soil depth as
shown in Table M-l.
(2) Linear Loading.
. Effective Length. The effective length
(L) of the mound for determining the
linear loading rate shall be the entire
length of sand fill at the downslope edge
"of :the mound. .The-effective length of
the primary and secondary (reserve)
mounds may overlap for purposes of
determining the linear loading rate.
. Wastewater Flow." The wastewater flow
used for determining the linear loading
rate shall be as follows:
- 100 gpd/bedroom for residential septic
systems;
- design sewage flow rate for
commercial, institutional, industrial
and multi-residential septic systems.
. Loading Rate. Maximum linear loading
rates for mound system sizing shall vary
according to ground slope, percolation
rate and soil depths as indicated in
Tables M-2 through M-4. If a variance
from these criteria is proposed, it must
be supported by detailed groundwater
mounding analysis carried out in
accordance with the guidelines contained
,in section 807 of these Regulations.
9. Dual Mound systems.
a. Dual system Requirement. Dual mound systems
shall be required in the following instances:
(1) For all commercial, institutional,
industrial and multi-residential septic
systems.
(2) For individual residential septic systems
where system sizing is reduced based upon
credit for water-saving plumbing.
A - 7
-~_.__-.-
-
(3) For any system where the sand fill run-out
of the upslope mound overlaps the sand fill
area of the downslope mound.
b. Intermittent Sand Filter Substitute. For existing
lots, the use of an Intermittent Sand Filter,
designed in accordance with applicable provisions
of these Regulations, between the septic tank and
mound system may be utilized in lieu of installing
a dual mound system. In such cases, a 100%
replacement area for the mound system, per B.7. of
these criteria, shall still be required.
c. Distribution Bed Placement. Dual mound systems
shall have at least two distinctly separate
distribution beds. The beds may be placed
within one continuous mound or in separate
mounds. The distribution beds may be placed
end-to-end or upslope/downslope of one another
subject to meeting minimum sizing requirements
for basal and linear loading rates per 8b(2)
above.
d. Distribution Bed separation. The minimum
lateral (Le. , end-to-end) separation between
distribution beds in a dual mound system shall
be six feet.
e. Effective Basal Area. For dual mound systems
the effective basal area for sizing the two
systems shall not overlap.
.
f. Alternate Dosing. The distribution beds for
dual mound systems shall be designed and
operated to provide alternate dosing and resting
of the beds, in the same manner as required for
other dual leachfield systems under these
Regulations.
10. Inspection Wells. A minimum of six inspection wells
shall be installed within and around mound systems as
follows:
a. One shall be located near the center of the mound,
extending from the mound surface to the bottom of
the gravel distribution bed.
b. One shall be located within the sand fill,
extending from the mound surface to 6 inches into I
the native soil. ,
A - 8
--~" 1 -. ~_.-
-"
c. Four shall be located respectively midway along
each of the four sides of the mound, near the toe
of the slope, extending from ground surface to a
depth of 5 feet.
d. Inspection wells shall be constructed of 2" to 4"
diameter pipe (or equivalent), equipped with a
wrench-tight cap or pipe plug and a bottom cap.
All wells shall be perforated beginning at a depth
of 18 inches below grade and extending to the
bottom of the pipe. Perforations shall consist of
hacksaw slots at nominal 1" spacing. Inspection
wells shall be sealed with. ~bentonite or concrete
annular seal (or equivalent) to prevent surface
infiltration.
D. Construction:
Construction of mound systems shall be in accordance with
guidelines contained in the following references:
L "Guidelines for Mound Systems", State Water
Resources control Board, January 1980.
2. "Design and construction Manual for Wisconsin
Mounds" , Small Scale Waste Management Project,
University of Wisconsin, Madison, September 1978.
3. "Design Manual - On-site Wastewater Treatment and
Disposal systems", U.S. Environmental Protection
Agency, October 1980.
Engineering plans for mound systems shall contain specific
step-by-step construction guidelines and notes for use by
the installer.
A - 9
-
:II . SITING AND DESIGN CRITERIA
FOR
STEEP SLOPE MOUND SYSTEMS
(CATEGORY 2 SYSTEM)
Setforth here are criteria for "steep Slope Mound Systems", which
are classified as a Category 2 System. This alternative system
may be used only for existing lots, and not for subdivision
purposes. The problems addressed, siting and design criteria,
and construction,:';;J:equb:::ements. are.>identical to those for
"Standard Mound Systems", with the exception of the items noted
here. The specific differences are to allow for: (a) the
placement of mound systems on slopes up to 20%; and, (b) the use
of tiered distribution beds within the mound.
A. Problems Addressed: Per Standard Mound Systems.
B. site criteria:
1- Setbacks. Per Standard Mound Systems.
!
2. Depth to Groundwater. Per Standard Mound Systems.
3. Soil Depth. Minimum depth of soil over bedrock or an
impermeable soil layer shall be 2 to 3 feet, ,
depending upon ground slope, percolation rate, and
linear loading rate per Tables M-S through M-7.
4. Depth to Fractured Rock. Per Standard Mound Systems.
5. Percolation Rate. Per Standard Mound Systems.
6. Slope. Maximum ground slope for steep slope mound
systems is as follows:
a. for soils having a percolation rate of 1 to 60
MPI: 20%
b. for soils having a percolation rate of 61 to 120
MPI: 6%
7. Reserve Area. Per Standard Mound Systems.
c. Design criteria:
1- Pretreatment. Per Standard Mound Systems.
2. Design Sewage Flow. Per Standard Mound Systems.
A - 10
_.~_.~~_.- ~ \- -- .- . - ----
~
3. Pressure Dosing. Per Standard Mound Systems.
4. Sand Fi~~. Per standard Mound Systems.
5. Grave~ Distribution Bed
a. Materia~. The distribution bed shall consist of
3/8-inch washed pea gravel, free of fines.
b. Depth. Peal gravel shall extend a minimum of 6
inches below the invert and 2 inches above the top
of the distribution piping.
c. width. Maximum width of the distribution bed
shall be as follows:
Slooe (%) Bed Width (Feet)
o - 12 1.0
1.3 9
14 8
15 - 16 7
17 - 1.8 6
1.9 - 20 5
For slopes of 1.2 percent or less, if a variance
from these criteria is proposed it must be
supported by detailed groundwater mounding
analysis carried out in accordance with
guidelines contained in section 807 of these
Regulations. No variance from these criteria
will be considered for slopes in excess of 1.2
percent.
d. Leve1.. The bottom of the distribution bed shall
be level; and the downslope side shall be
parallel to the slope contour.
e. Tiered Beds. Tiered distribution beds, a
maximum of two, may be installed within a single
continuous mound provided that:
(1) the beds are separated by a minimum of
6 feet;
(2) the space between the beds is filled
with sand;
(3) maximum basal and linear loading
requirements are not exceeded; and,
(4) the effective basal area for sizing the
two beds shall not overlap.
A - 11
-
Additionally, for tiered beds, the upslope
horizontal sand fill extension requirement (per
4.c(1) above) shall apply only to the uppermost
distribution bed; and the downslope sand fill
extension requirement shall apply only to the
most downslope distribution bed.
6. silt Barrier. Per standard Mound Systems.
7. Soil Cover. Per Standard Mound Systems.
8. Wastewater Loading Rate. Per Standard Mound Systems,
wi th the -exception.. that '..Linear.Loading Rate criteria
are as provided in Tables M-5 through M-7.
9. Dual Mound systems. Per Standard Mound Systems.
10. Inspection Wells. Per.standard Mound systems.
.'
D. Construction: Per Standard Mound Systems.
A - 12
.-. ~
--
. -
TABLE M -1
WASTEWATER LOADING RATES
FOR MOUND BASAL AREAS
W ASTEW A TER LOADING RATE
PERCOLATION RATE (MPI) (GPD/FT2)
1 to 30 1.2
31 to 90 1.5 x STP
.
91 to 120 0.2
* STE - Standard wastewater' loading rate for septic tank effluent per Section 603B.
-
1.4
1.2 ,r-- 12
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10 20 120
PRECOLATION RATE (UP')
WASTEWATER APPLICATION RATES FOR POST SYSTEMS
90304REV.TMl
, A - 13 -
-
, TABLE M -2 ..
MAXIMUM MOUND LINEAR LOADING RATE (GPD/L.F.)
FOR
SOIL DEPTH = 2.0 TO 2.5'
(STANDARD MOUND SYSTEMS)
PERCOLATION GROUND SLOPE ("10)
RATE
(MPI) 0-2% 3 - 5% 6% 7-8% 9 - 10% 11 - 12"1.
1 to 5 NA 9 10 11 12 12
,
6 to 10 NA 8 9 10 11 12
11 to 20 NA 7 8 9 10 II
21 to 30 NA 6 . 7 8 9 10
31 to 40 NA 5 6 7 8 9
41 to 50 NA 4 5 6 7 8
51 to 60 NA 3 4 5 6 7
61 1090 NA 3 3 NP NP NP
.-
91 10 120 NA 3 3 NP NP NP
NA - Not Applicable; system design based on basal area sizing
NP - Not Permilled
90J04REV,TM2
A - 14
, ..
------~- -----,---r-- ----
,
-
TABLE M -3
MAXIMUM MOUND LINEAR LOADING RATE (GPD/L.F.)
, -
FOR
SOIL DEPTH = 2.5 TO 3.0'
(STANDARD MOUND SYSTEMS)
PER COLA nON GROUND SLOPE (%)
RATE
(MPI) 0-2% 3 - 5% 6% 7 - 8% 9 -10% II - 12%
I to 5 NA 10 11 12 12 12
6 to 10 NA 9 10 11 12 12
11 to 20 NA 8 9 10 II . 12
21 to 30 NA 7 8 9 10 11
. 31 to 40 NA 6 7 8 9 10
41 to 50 NA 5 6 7 8 9
51 to 60 NA 4 5 6 7 8
61 to 90 NA NA NA NP NP NP
91 to 120 NA NA NA NP NP NP
NA - Not Applicable; system design based on basal area sizing -
NP = Not Permitted
90304REV.TM3
A - 15
~
TABLE M-4
MAXIMUM MOUND LINEAR LOADING RATE (GPD/L.F.)
, -
FOR
SOIL DEPTH = > 3'
(STANDARD MOUND SYSTEMS)
PERCOLA nON GROUND SLOPE (%)
RATE
(MPI) 0-2% 3 - 5% 6% 7 - 8% 9 - 10% 11 - 12%
1 to 5 NA 11 12 12 12 12
6 to 10 NA 10 11 12 12 12
11 to 20 . NA 9 10 11 12 12 .
21 to 30 NA 8 9 10 II 12
31 to 40 NA 7 8 9 10 11
41 to 50 NA 6 7 8 9 10
51 to 60 NA 5 6 7 8 9
61 to 90 NA NA NA NP NP NP
91 to 120 NA NA NA NP NP NP
NA - Not Applicable; system design based on basal area sizing "
NP - Not Permitted
90J04REV.TM4
A - 16
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- . BASAL AREA AND LINEAR LOADING CRITERIA
.
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BASAL AREA AND LINEAR LOADING CRITERIA
A - 23
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BASAL AREA AND LINEAR LOADING CRITERIA
A - 25
-
~
I I:I. SITING AND DESIGN CRITERIA
FOR
PRESSURE-DOSED SAND TRENCHES (PDST)
(CATEGORY 2 SYSTEM)
A. Problems Addressed:
1. Rapid percolation; and,
2. Groundwater.separation.
B. Siting criteria:
All siting criteria for standard septic tank-Ieachfield
systems apply for the use ..r;Jf PDST systems, with the
following exceptions:
1- Percolation Rates. PDST systems may be used in
soils having percolation rates of 1 to 120 MPI.
2. Soil Depth. Minimum depth of soil (below sand) for
PDST systems shall be 2 feet.
3. Depth to Groundwater and Well Setback Distances.
For PDST systems, the minimum depth to the
anticipated highest seasonal level of groundwater
below the bottom of the trench and corresponding
well setback distances shall be as shown in Table
PDST-1.
4. Soil Characteristics. PDST systems shall be
permissible in areas having soil conditions which
are normally suitable for standard leachfields
under these Regulations.
c. Design criteria:
1- Pretreatment. PDST systems may receive either
primary (septic tank) or secondary effluent,
treated in accordance with applicable Marin County
Regulations, respectively, for septic tanks and
Intermittent Sand Filters, or other approved
pretreatment units that are allowed under these
Regulations.
2. Dual system Required. All PDST systems shall be
installed as dual systems, with each half sized to
A - 26
~- ----- T - --:-. --
-
accommodate 100-percent of the design wastewater
flow.
3. Trench width. Trench width shall be a minimum of
12 inches and a maximum of 36 inches. Trench
widths in excess of 36 inches are considered to
constitute absorption beds and may be permissible
for soils having percolation rates of 30 MPI or
faster and if the design proposal is supported by
an appropriate analysis of potential groundwater
mounding effects and suitable construction
specifications for absorption beds. Trench widths
in excess, of.36 inches,sha,lJ;:.:require more than one
distribution lateral per Cae.
4. Trench spacing. Minimum spacing between trench
sidewalls shall be 6 feet, plus an additional one
(1) foot for each 5%,drainfield area slope over
20%. Greater trench 'spacing may be required for
systems with trench widths in excess of 36 inches,
as determined by groundwater monitoring analysis
per C3 above.
5. Required Trench Application Area. The required
("effective") application area for system sizing
shall be the trench bottom area or the drain rock-
sand interface, whichever is more restrictive.
6. Wastewater Loading Rates. Maximum wastewater
loading rates for system sizing shall be as
follows, whichever is more restrictive:
a. Drain Rock - Sand Interface
(1) 1.2 gpdjft2 for individual residential
septic systems.
(2) 1.0 gpdjft2 for commercial, industrial,
institutional,andmulti-residential
septic systems.
Reduction in the above wastewater loading
rates or other provisions to insure the long-
term integrity and performance of the PDST may
be required for high strength waste flows,
such as from restaurants.
b. Sand - soil Interface. The wastewater loading
rate at the sand-soil interface (considering
bottom area only) shall be according to
percolation rate as shown Table PDST-2. These
A - 27
-
rates apply for POST systems receiving septic
tank effluent. For POST systems receiving sand
filter effluent, the loading rate shall be as
specified in Table SF-l for Intermittent Sand
Filters.
7. Drainrock.
a. Material. The distribution bed shall consist of
3/8-inch washed pea gravel, free of fines.
b. Depth of Rock. Pea gravel shall extend a
minim='of 6 inches below:_the invert and 2
inches above the top of the distribution piping.
8. Pressure Distribution System. POST systems require
the use of a pressure distribution system. The
pressure distributio~,system shall be designed in
accordance with accepted engineering practices to
achieve, at a minimum:
a. Uniform dosing of effluent per lineal foot of
leaching trench;
b. Adequate flow rate, screening of effluent and
suitable piping network to preclude solids
accumulation in the pipes or clogging of
discharge orifices;
c. Suitable access provisions for inspection,
testing and adjustment of the pressure
distribution system;
d. Dosing volume to achieve 3 to 5 doses per day at
design flow conditions; and,
e. At least one distribution lateral for every 36
inches of trench width.
A - 28
-- ~---- 1 - - - ~_..__.-
~
9. Sand Fill.
a. Sand Specifications. The sand media shall be a
medium to coarse sand which meets the following
gradation specifications:
sieve Size Percent Passino
3/8 100
#4 90 - 100
#10 62 - 100
#16 45 - 82
#30 25 - 55
#50 5 - 20
#60 o - 10
#100 o - 4
b. Depth of Sand. The.minimum depth of sand below
the drain rock shall be as follows:
(1) For septic tank effluent: 12"
(2) For sand filter effluent: 6"
For PDST systems receiving septic tank effluent,
the depth of sand fill shall be increased to 24
inches where deemed necessary by the Health
Officer for protection of public health,
including sites where all of the following
conditions exist:
. Percolation rates are faster than 10 MPI;
. Groundwater immediately beneath the system is
hydraulically connected to a definable
aquifer; and,
. Groundwater in the immediate project area is
an existing or potential domestic water
source.
10. silt Barrier. The gravel and distribution piping
shall be covered (over the top) in its entirety
with a geotextile ("filter fabric") silt barrier.
Filter fabric shall be either polyester, nylon or
polypropylene, or any combination thereof, and
shall be suitable for underdrain applications.
Filter fabric shall be non-woven, shall not act as
a wicking agent and shall be permeable.
A - 29
-
~
--
11- Soil Cover. The minimum required soil cover (i.e.,
trench backfill) above the drain rock shall be
based upon ground slope and percolation rate as
shown in Table PDST-3.
12. Fill. POST systems may be installed in conjunction
with fill (to meet trench backfill requirements)
installed in accordance with Section 604A of these
Regulations, with the following additional
provisions:
. POST systems with fill may be used on slopes up
to..2 o "percent, ,.where,. the.::percolation rate is 60
MPI or faster;
. POST systems with fill may be used where the
percolation rate is between 60 and 120 MPI on
slopes up to a max~~um of 12~ percent.
13. Inspection Wells. Two inspection wells shall be
installed in each individual trench section as
follows:
. One inspection well shall extend from finished
grade to the pea gravel-sand interface. It
shall be perforated in the pea gravel zone only.
. One inspection well shall extend from finished
grade to the sand-soil interface. It shall be
perforated in the sand zone only.
Inspection wells shall be 2" to 4" diameter plastic
pipe and fitted with a wrench-tight cap or pipe plug
and a bottom cap. Perforations shall consist of
hacksaw slots at nominal 1" spacing. Inspection
wells shall be sealed against surface infiltration
with a bentonite or concrete annular seal through the
soil backfill zone.
The Health Officer may require the installation of
additional inspection wells in areas upgradient,
between or downgradient of disposal trenches for the
purpose of monitoring groundwater levels or for water
quality sampling. The location and depth of such
additional inspection wells shall be determined on a
case-by-case basis, and shall be specified in the
permit.
A - 30
-- ~--- :-- - - -
~
'.
TABLE PDST - 1
SITING CRITERIA FOR PDST SYSTEMS
.
MINIMUM DEPTH TO WELL
PERCOLATION RATE" PERCENT FINES" SEASONALLY HIGH SETBACK
(MPI) (SILT + CLAY) GROUNDWATER (IT) (IT)
Slower than 5 N/A 2 lOa
I to 5 > 15 2 IDa
I to 5 10 to 15 5 IDa
I to 5 < 10 10 100
* Percolation .rate of soils at the proposed trench bottom depth or within two feet below
trench bottom.
*' Percent by weight for the soil fractiol!'. exclusive of coarse fragments larger than 2mm in
size; applies to soil from either- within the trench zooe or within the two feet of soil below
the trench bottom.
, ..
..
.8- .,:,:iL
-
'.
TABLE PDST - 2
WASTEWATER APPLICATION RATES
FOR PDST SYSTEMS
WASTEWATER LOADING RATE
PERCOLATION RATE (MPI)l (GPD/IT2)
1 to 5 " 1.2
6 to 24 ,1.2
25 to 60 - 2.0 x STE2
61 to 90 1.5 x STE2
91 to 120 0.2
1 Percolation rates of soils at the proposed trench bottom depth or within two feet below trench
bottom. : ..~
2 STE - Standard wastewater loading rate for septic tank effluent per Section 603 of these
regulations.
1.4
1.2 ,..--"
~ 1.0
~
!2.
w
~
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0 0.8
F
<
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~
<
'" 0.8
w
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~ 0.4 0.35
0.2
0.0
10 20 3J 40 so 60 10 '" 120
PAECOLATlON RATE (Mfll)
WASTEWATER APPLICATION RATES FOR POST SYSTEMS
A - 32
-~-,- - -
~
TABLE PDST - 3
SOIL COVER REQUIREMENTS
FOR PDST SYSTEMS -
DEPTH OF BACKFILL (inches)
GROUND SLOPE
('70) 1-30MPI 31 - 120 MPI
0-20 12 12
21 - 30 15 18
31 - 40 18 24
> 40 24 30
-
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A - 33
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IV. SITING AND DESIGN CRITERIA
FOR
INTERMITTENT SAND FILTER SYSTEMS
(CATEGORY 2 SYSTEM)
A. Problems Addressed:
1. Rapid percolationr
2. Groundwater separation; and,
3. stream setbacks.
B. Siting criteria:
1. Sand Filter Treatment Unit. All siting criteria for
septic tanks apply equally to sand filter treatment
units and associated pumping equipment.
2. Leachfield systems. Leachfield systems receiving
sand filter effluent are subject to all siting,
design and construction criteria for standard septic
tank-leachfield systems except as modified by the
minimum requirements shown in Table SF-l pertaining
to: (a) percolation rate; (b) wastewater
application rates; (c) depth to groundwater; and,
(d) well and stream setbacks. Additionally, sand
filter effluent may be applied to Pressure-Dosed Sand
Trench (POST) leachfield systems or to Mound systems,
subject to the siting, design and construction
criteria specified in these Regulations for POST and
Mound systems.
c. Design criteria:
1. Sand. Filter Treatment unit.-
a. Pretreatment. The sand filter treatment unit
shall be preceded by a septic tank, sized for
the projected system sewage flow in accordance
with Section 602 of these Regulations.
b. Pressure Dosing. Septic tank effluent shall be
applied to the sand filter treatment unit by
pressure dosing, utilizing either an automatic
dosing siphon or pump system. The pressure
distribution system shall be designed in
A - 35
-
,
accordance with accepted engineering practices
to achieve, at a minimum:
(1) Relatively uniform dosing of septic tank
effluent over the surface application area
of the sand filter;
(2) Adequate flow rate, screening of effluent
and suitable piping network to preclude
solids accumulation in the pipes or !
clogging of discharge orifices;
(3) ..:.Suitable;:.a"ccess:: .provisi-onsfor inspection,
testing and adjustment of the pressure
distribution system;
(4) Dosing volume to achieve 3 to 5 doses per
day at design flow conditions; and,
"
(5) At least one distribution lateral for every
36 inches of bed width.
c. Wastewater Loading Rate. The wastewater loading
rate used for sizing the surface area of the
sand filter shall be as follows:
(1) 1.2 gpd/ft2 for individual residential
septic systems.
(2) 1.0 gpd/ft2 for all commercial, industrial,
institutional, and multi-residential septic
systems.
Reduction in the above wastewater loading rates
or other provisions to insure the long-term
integrity and performance of the sand filter may
be required for high strength waste flows, such
as_those from restaurants.
d. containment Liner. The sand filter shall be
provided with an impermeable containment liner
to prevent leakage out of or into the filter.
The liner shall consist of either: (a) 30 mil
plastic; or, (b) reinforced, poured-in-placed
concrete.
e. Finished Grade. The finished grade of the sand
filter shall be at or above the surrounding
ground elevation. Above-ground installation
shall be structurally supported with retaining
wall(s), as required.
A - 36
---- -.-- --,,--- --
-
.
f. Shape. The sand filter shall not be restricted
as to its shape in plan view.
g. Kultiple units. The sand filter may be divided
into compartments or multiple units.
h. sand Filter Media
(1) Sand Specification. The sand media shall
be a medium to coarse sand which meets
the following gradation specifications:
sieve size Percent passinq
3/8 100
#4 90 - 100
#10 62 - 100
#16 45 - 82
#30 25 - 55
#50 5 - 20
#60 o - 10
#100 o - 4
(2) Sand Depth. The minimum sand depth below
the gravel distribution bed shall be 24
inches.
i. Gravel Distribution Bed
(1) Material. The distribution bed shall
consist of 3/8-inch washed pea gravel, free
of fines.
(2) Depth. Pea gravel shall extend a minimum
of 6 inches below the invert and 2 inches
above the top of the distribution piping.
j. siLt Barrier. The gravel distribution bed shall
be__cov-ered in its entirety:with a geotextile
("filter fabric") silt barrier. Filter fabric
shall be either polyester, nylon or polypropylene,
or any combination thereof, and shall be suitable
for underdrain applications. Filter fabric shall
be non-woven, shall not act as a wicking agent and
shall be permeable.
k. Soil Cover.
(1) Material. A soil cover shall be placed
over the distribution bed, consisting of a
medium, loamy-textured soil.
A - 37
--------
-
(:!) Depth. Soil cover depth shall be a minimum
of 12 inches and a maximum of 18 inches
over the top of the distribution bed. Soil
cover shall be crowned or sloped to promote
rainfall runoff.
l. Underdrain
(1) Material. The underdrain beneath the sand
media shall consist of 3/8" washed pea
gravel with 3 or 4-inch diameter perforated
drain pipe; perforations in the drain pipe
.. shall be .no greater than 1/8" in width or
diameter.
(2) Depth. The pea gravel underdrain shall
have a minimum depth of 9 inches.
.l'
(3) Grade. The underdrain shall be constructed
and the drain pipe laid with a minimum
grade of 1% toward the outlet point.
(4) watertight Outlet "Boot". The sand filter
underdrain shall be equipped with a
watertight outlet "boot" for connection of
piping to the leachfield or the leachfield
dosing chamber. Testing of the "boot" for
watertightness shall be required during
construction (Note: Outlet "boot" shall
not be required if sand filter is equipped
with internal pump system).
m. Clean-out Riser. For clean-out and inspection
purposes the upslope end of the perforated drain
pipe in the underdrain shall be equipped with a
vertical riser constructed of non-perforated
pipe of equal diameter. The riser shall extend
to finished grade of the sand filter.
n. Inspection Wells. An inspection well shall be
installed in the gravel distribution bed of each
sand filter compartment. The inspection well
shall extend from finished grade to the pea
gravel-sand interface and shall be perforated in
the pea gravel zone only. Inspection wells
shall be 2" to 4" diameter plastic pipe and
fitted with a wrench-tight cap or pipe plug and
a bottom cap. Perforations shall consist of
hacksaw slots at nominal 1" spacing. Inspection
wells shall be sealed against surface
A - 38
- -~ --- ~
~
infiltration with a bentonite or concrete
annular seal through the soil backfill zone.
o. Internal Pump system. In lieu of gravity flow
from the sand filter to the leachfield (or
leachfield dosing system), an internal pump
system may be installed within the sand filter
for dosing directly to the leachfield. In such
applications: (1) the pump chamber must be
seated at or below the bottom of the underdrain;
(2) the pump operating depth must be entirely
within the depth of the underdrain; and, (3)
storage volume equal_ to .:50 percent of the
leachfield dose volume must be provided in the
network of perforated drain pipe within the
underdrain.
2. Leaohfield Systems. ~and filter effluent may be
discharged to standard drainfields, mounds or
Pressure-Dosed Sand Trench systems. Design of
these leachfield systems shall in accordance with
applicable criteria specified elsewhere in these
Regulations (Section 603 for Standard Drainfields,
and Appendix A for Pressure-Dosed Sand Trenches and
Mound Systems) , except that leachfield sizing shall
be in accordance with the wastewater loading rates
specified in Table SF-1.
D. construotion
Engineering plans for Intermittent Sand Filter systems
shall contain specific step-by-step construction
guidelines and notes for use by the installer.
A - 39
--
T A B L E SF-J.
LEACHFIELD REQUIREMENTS FOR .--
BAND FILTER EFFLUENT
'0
" MINIMUM
PERCENT WASTEWATER MINIMUM MINIMUM SETBACK TO WATER
FINES .L9ADING DEPTH TO -' WELL BODIES (FT)
PERCOLATION (SILT + LEACHFIELO RA~E GROUNDWATER SETB1\ClC
RATE (MPI) 1 CLAY) DESIGN (GPD/Frl 1FT)' (FT) Ephemeral Perennial
stream. or stream or
Wetland Lake
1 to 5 > 15% Standard Gravity' 1.8 2 100 75 100
2.4 3 100 75 100
, 1.2 3 100 - 50 75
i; PO Sand Trench' 2.4 2 100 75 100
. 1.2 3 100 50 75
10 to 15t Standard Gravity' 1.2 5 100 75 100
PO Sand Trench' .l!:S 5 100 75 100
1.2 J 100 75 100
1.2 10 100 50 75
< lot Standard Gravity3 0.6 10 150 75 100
0.6 5 200 75 100
PO Sand Trench' 1.2 10 100 75 100 _
-
1.2 5 150 75 100
0_6 J 200 . 75 100
1.2 20 100 50 75
5 to 90 N/A Standard Gravity! 2.0 x STE~ 3 100 75 100
1. 5 x S'I'E' 2 100 75 100
1. 0 x STES 3 100 50 75
-, ,
PO Sand Trench' 2.0 x STE5 2 100 75 100 .
1.5 X STE5 3 100 50 75
90 to 120 N/A Standard Gravity' O.J 2 100 75 100
0.2 3. 100 50 75
PO Sand Trench' 0.4 2 100 75 100
O.J 3 100 50 75
"
1 Percolation rate of soils at the proposed trench bottom dept~ or within two feet below
trench bott<,m. .
2 Below trench bottom.
3 Standard gravity drainfield trenches per Section 603 of these Regulations, with the
exception that trench width may be reduced to 12 inch minimum.
4 Pressure-Dosed Sand Trench per Appendix A of these Regulations.
, STE = Standard wastewater loading rate for septic tank effluent per Section 60J8 of
these Regulations.
A - 40
-~._- ----- - -- --- - -_.~---
.
-
0
Sec. l3C-I
CHAPTER 13C. Individual sewage disposal system. Any sys-
tem of piping, treatment devices or other facili-
INDIVIDUAL SEWAGE DISPOSAL ties (excluding chemical toilets) that store,
SYSTEMS. convey, treat or dispose of sewage which is dis-
charged anywhere other than into a public sewer
system.
Sections: Person. Any person, firm, association, corpo-
13C-L Purpose. ration or any members, agents or employees of
13C-2. Applicability of chapter. the foregoing.
13C-3. Definitions. Public sewer system. Any publicly owned and
13C-4. Prohibited acts. maintained system of sewage conveyance, piping
13C-5. Connection to public sewer or any part thereof, that transports sewage away
system and alternatives. from the properties of origin to publicly owned
13C-6. Regulations. and operated sewage treatment and disposal
13C-7. Application and fee. facilities.
13C-8. City health officer review. Sewage. Any and all wastes, substance, liquid
13C-9. Certificate of inspection. or solid, which contain or may be contaminated
13C-I0. Biennial inspection and renewal. by human excreta, excrement, offal or feculent
13C-ll. Recordation and transfer of matter or matters, or substances of any kind or
certificate. nature that may be injurious or dangerous to
13C-12. Defective systems. health, either directly or indirectly. (Ord. No. 141
13C-13. Enforcement of chapter. N.S., S 1.)
13C-14. Appeals. See"13C4. Prohibited acts.
13C-15. Violations.
It shall be unlawful for any person to do any of
the following without first obtaining approval
See. 13C-1. Purpose. from the town health officer in accordance with
The provisions of this chapter are intended to the provisions of this chapter and the regulations
insure that the disposal of sewage shall be accom- issued hereunder.
plished in a safe and sanitary manner in order to (a) Construct, alter, repair or replace an indi-
protect the public health, safety and welfare to vidual sewage disposal system or a component
the greatest extent possible. (Ord. No. 141 N.S., S element thereof, which system is subject to the
1.) provisions of this chapter.
(b) Construct, rebuild, use, occupy or main-
Sec. 13C-2. Applicability of chapter. tain any residence, place of business or other
This chapter is applicable to all individual structure where persons reside, congregate or are
sewage disposal systems heretofore or hereafter employed, which is not provided with a means of
constructed. (Ord. No. 141 N.S., S 1.) disposal of sewage by connection to a public
sewer system or which is not provided with a
See 13C-3. Definitions. sewage disposal system for which a prior permit
For the purposes of this chapter, the following has been lawfully issued. (Ord. No. 141 N.S., S 1.)
words and phrases shall have the meanings Sec. 13C-5. Connection to public sewer
re~ctively ascribed to them by this section: system and alternatives.
City .health officer. The Marin County health Sewage disposal shall be by means of a connec-
officer or his authorized representatives. tion to a public sewer system if the nearest sewer
96
T;"1..--.Tn-cr. . 1
li ~':i.ril ;:-..yu '::7--
_:...:..I-..t...L _~.L '__
~~- - ._~-~
.
-
~
Sec. 13C-5
is within four hundred lineal feet of the parcel in with this chapter, and any reguJations issued pur- ~.
which the structure generating the sewage is to be suant thereto. Any such approval shall become
constructed. This requirement may be waived by null and void under the following circumstances:
the town health officer ifhe finds connection to a (a) The work authorized has not been com-
public sewer is legally or physically impossible. If menced within one year after approval, unless an
the town health officer det=ines that connee- extension of an additional one year has been
tion to a public sewer is unfeasible, an applica- granted by the town health officer.
tion may be filed for a permit for an alternative (b) Construction of the approved system is
method of sewage disposal, utilizing an indi- commenced but subsequently abandoned for a
vidual sewage disposal system. (Ord. No. 141 continuous period of ninety days.
N.S.,~ 1.) (c) Construction of the approved system is
not proceeding in accordance with the terms of
See. 13C-6. Regulations. approval. (Ord. No. 141 N.S., ~ 1.)
The town health officer is authorized to issue
regulations, guidelines and criteria to carry out Sec.l3C-9. Certificate of inspection.
the purposes of this chapter. Such regulations
shall be approved by the town council prior to If the individual sewage disposal system is
their effectiveness. The town health officer is completed in accordance with the terms of the
authorized to waive any particular requirement town health officer's approval, a certificate of
imposed by such regulations if he determines inspection shall be issued by the town health
that the general purposes of this chapter will be officer, which certificate shall be effective for a I
achieved by such waiver. (Ord. No. 141 N.S., ~ 1.) period of two years. The town health officer may
revoke any certificate if he determines that the
See.l3C-7. Application and rei!. individual sewage disposal system does not coin-
All applications for individual sewage disposal ply with the provisions ofthis chapter, the regula-
systems shall be submitted in writing to the town tions issued hereunder, or the conditions of the
health officer on a form supplied by such officer. certificate. (Ord. No. 141 N.S., ~ I.)
The application shall be accompanied by a fee of I
-f'ortY'dollars to assist in covering the costs of See. l3C-10. Biennial inspection and
initial design review and field inspection. renewal.
Applications shall contain all appropriate infor- E very individual disposal system shall be sub-
mation regarding the site and the proposed sys- ject to a biennial inspection to assure its
tem. (Ord. No. 141 N.S., ~ 1.) continued proper functioning and for the pur-
pose of renewing the certificate of inspection.
See. 13C-8. CitY)ealth officer review. The town health officer shall renew a certificate
If, after investigation. the town health officer of inspection for a two-year period if the follow-
determines that the construction of the proposed ing conditions have been met:
facility is in accordance with the terms of this (a) A report of inspection of the individual
chapter and any regulations issued pursuant disposal system by an authorized inspector indi-
thereto, and will not be injurious to the public cates that the system is operating in a satisfactory
health and welfare, he shall approve or condi- manner.
tionally approve the application for an indi- (b) Proof of a septic tank pumping by a
vidual sewage disposal system. Such approval licensed septic tank pumper is submitted, when
may be made subject to such conditions as such such pumping is required by the report of the
officer deems necessary to insure compliance inspector.
97
-.......- ---~-- - - ----
~
Sec. 13C-1O
(c) Proof of repairs or alterations to an indi- obtained, the town health officer shall first obtain
vidual sewage disposal system is submitted, an inspection warrant pursuant to applicable
when such repairs have been _required by the law. (Ord. No. 141 N.S., ~ 1.)
report of the inspector. '/ Sec. l3C-I4. Appeals.
(d) A deposit of~~llar renewal fee If an applicant or holder of a certificate of
is made with the town ih officer. (Ord. No. inspection is dissatisfied with any action or deter-
141 N.S., ~ 1.) mination of the town health officer pursuant to
this chapter, he shall have the right to appeal to
Sec. l3C-H. Recordation and transfer of the town council, in writing, within ten days after
certificate. notification of the action of the town health
The certificate of inspection shall be recorded officer. Upon receipt of such appeal, the town
council shall set a hearing within thirty days. The
by the town health officer with the county appellant shall be given notice thereof at the
recorder, identifying the property by assessor's address shown on the application by registered or
parcel numbers. The certificate of inspection is certified mail. At the conclusion of the hearing,
transferable to a subsequent grantee or transferee the town council shall render a decision which
of the property, effective for the balance of the shall be final. (Ord. No. 141 N.S., ~ 1.)
two year period. (Ord. No. 141 N.S., ~ 1.) Sec. l3C-I5. Violations.
The construction, rebuilding, repair, use or
Sec l3C-l2. Defective systems. maintenance of any sewage disposal system in
Following the biennial inspection mentioned violation of the provisions of this chapter or any
above, if an individual sewage disposal system is regulation issued hereunder, or the construction,
found to be defective, the prior certificate of rebuilding, repair, use, maintenance or occu-
inspection may be extended for a period not to pancy of any structure in which persons reside,
exceed six months beyond its normal expiration congregate or are employed, which structure is
date, provided that corrective measures as rec- not provided with a means of disposal of sewage
ommended by the inspector are being under- by connection to a public sewer system or with a
taken. (Ord. No. 141 N.S., ~ 1.) sewage disposal system in compliance with the
provisions of this chapter and any regulations
Enforcement of chapter. issued hereunder, which system shall not be
Sec. l3C-l3. defective, is unlawful and constitutes a public
It shall be the duty of the town health officer or nuisance. The town attorney, upon order of the
his duly authorized representative to enforce the town council, shall immediately commence
provisions of this chapter and the regulations action for the abatement, restraining and enjoin-
issued thereunder. He may enter any premises at ment of such violation in the manner prescribed
any reasonable hour, with the owner's consent, by law. The remedies provided in this section are
to inspect the individual sewage disposal system cumulative and shall not exclude other remedies
to determine if it is functioning satisfactorily. for violation as provided by other laws or ordi-
Should for any reason the owners consent not be nances. (Ord. No. 141 N.S., ~ I.)
98
",_._--,.-, .-..-.....- --- --...-. _....._.~-~