These technical standards provide criteria for the design and
construction of onsite wastewater treatment and disposal technologies
and components, in order to obtain an OWTS construction permit.
(Ord. 435 § 3, 2018)
Definitions established in Section 15.40.020 (Chapter 15.40) of the Malibu Municipal Code shall apply to this chapter.
(Ord. 435 § 3, 2018)
Any new or replacement OWTS shall comply with the following
requirements. Repair of any lawfully existing OWTS, where no expansion
or intensification of use is proposed, shall conform to these requirements
to the greatest extent practicable as determined by the administrative
authority.
A.
Soil
Depth. For conventional OWTS discharging septic tank effluent, minimum
depth of soil beneath the bottom of the dispersal field shall be five
feet for leaching trenches/beds and 10 feet for seepage pits. Where
advanced treatment is provided, minimum soil depth for leaching trenches/beds
may be reduced to three feet. Where advanced treatment and subsurface
drip dispersal methods are used, minimum soil depth may be reduced
to two feet below the drip line.
B.
Vertical Separation to Groundwater. For new conventional OWTS discharging septic tank effluent, minimum vertical separation between the bottom of the dispersal system and seasonal high groundwater depth level shall be five feet for leaching trenches/beds and 10 feet for seepage pits. For advanced OWTS where supplemental treatment is provided, minimum groundwater separation for leaching trenches and beds may be reduced to three feet. For advanced OWTS where supplemental treatment and either pressure distribution or subsurface drip dispersal methods are used, minimum depth to groundwater may be reduced to two feet below the trench/bed or drip line, as applicable. Determination of compliance with the above groundwater separation requirements shall account for any projected water table rise as determined through groundwater mounding analysis, where applicable (see Section 15.40.090).
C.
Soil
Percolation. For conventional dispersal trenches/beds the soils shall
have a demonstrated percolation rate in the range of five to 60 minutes
per inch (mpi). Absorption rates for seepage pits must not be less
than 0.83 gallons per square foot and must include supplemental treatment.
Horizontal dispersal systems (trenches, beds, drip) in soils with
percolation rates in the range of one to five mpi (fast percolation)
must have supplemental treatment and pressure distribution. Soils
with percolation rates of 60 to 120 mpi (slow percolation) are only
permissible for effluent disposal with advanced OWTS that includes
supplemental treatment and subsurface drip dispersal. The applicable
percolation test method is described in the Malibu OWTS Manual.
D.
Ground
Slope. No soil absorption fields shall be located on slopes greater
than 45%. Conventional gravity trench leachfields shall not be installed
on slopes greater than 30%. Soil absorption fields located on slopes
between 30 and 45% shall be designed to address critical factors of
soil depth, restrictive horizons, soil permeability, application rates
and dispersal methods. Siting of effluent dispersal systems on slopes
greater than 10% shall be evaluated to assess possible impacts of
lateral migration of effluent. The evaluation results, along with
an evaluation of slope stability, shall be submitted for review and
approval.
E.
Horizontal
Setbacks. Minimum horizontal setback distances from various site features
to OWTS components shall be as listed in Table 15.42.030(E).
|
Table 15.42.030(E)
Minimum Horizontal Setback Distances for OWTS (feet)
| ||||
|---|---|---|---|---|
|
Site Feature
|
Building Sewer
|
Septic Tank
|
Dispersal Trench or Bed
|
Seepage Pit
|
|
Buildings or structures1
|
2
|
5
|
8
|
8
|
|
Property line
|
Clear2
|
5
|
5
|
8
|
|
Water supply wells
|
|
|
|
|
|
Domestic
|
503
|
150
|
150
|
150
|
|
Public
|
503
|
150
|
1504
|
2004
|
|
Springs
|
-
|
50
|
100
|
100
|
|
Streams
|
|
|
|
|
|
General (from top of bank)
|
50
|
100
|
100
|
150
|
|
Between 1,200'—2,500' of a public water intake5
|
-
|
-
|
200
|
200
|
|
Within 1,200' of a public water system intake5
|
-
|
-
|
400
|
400
|
|
Reservoirs
|
|
|
|
|
|
General
|
50
|
100
|
200
|
200
|
|
Within 1,200' of a public water supply intake5
|
-
|
-
|
400
|
400
|
|
Ocean waters (from mean high tide line)6
|
-
|
50
|
100
|
100
|
|
Storm drainage pipe7
|
|
5
|
50
|
50
|
|
Cut bank or embankment
|
-
|
10
|
4 x h8
|
4 x h8
|
|
Unstable land mass9
|
|
100
|
100
|
100
|
|
Trees
|
-
|
10
|
-
|
10
|
|
Seepage pit
|
-
|
5
|
5
|
12
|
|
Dispersal trench or bed
|
-
|
5
|
4
|
5
|
|
Distribution box
|
-
|
-
|
5
|
5
|
|
Onsite domestic service line
|
110
|
5
|
5
|
5
|
|
Pressure public water main
|
1011
|
10
|
10
|
10
|
|
Notes:
| |
|---|---|
|
1
|
Including porches and steps, whether covered or uncovered, breezeways,
roofed porte cocheres, roofed patios, carports, covered walks, covered
driveways, and similar structures and appurtenances.
|
|
2
|
See California Plumbing Code, Section 321.3.
|
|
3
|
Drainage piping shall clear domestic water supply wells by not
less than 50 feet. This distance shall be permitted to be reduced
to not less than 25 feet where the drainage piping is constructed
of materials approved for use within a building.
|
|
4
|
200 feet for trench or seepage pit 10 feet deep; 2-yr microbial
travel study required for seepage pit >20′ deep within 600
feet of public water well, per Statewide OWTS Policy Section 9.4.10.3.
|
|
5
|
For areas tributary to and upstream of water supply intake;
setback distance measured from high water mark. Exceptions allowed
per Statewide OWTS Policy, as follows: (a) for replacement OWTS, comply
to the maximum extent practicable and incorporate supplemental treatment
unless the administrative authority finds no impact or significant
threat to water source; (b) for new OWTS on pre-existing lot of record
(pre-May 13, 2013), comply to maximum extent practicable and incorporate
supplemental treatment for pathogens per Sections 10.8 and 10.10 of
Statewide OWTS Policy as detailed in the Malibu OWTS Manual.
|
|
6
|
Systems that provide supplemental (secondary or tertiary) effluent
treatment prior to discharge to the subsurface effluent dispersal
systems are not required to meet these minimum horizontal setback
requirements provided that no parts of the OWTS are, at any time,
submerged or exposed to direct contact with these surface water bodies.
In the case of beachfront developments and redevelopments, the OWTS
shall, to the maximum extent feasible, be located at the farthest
point from the ocean on a parcel to avoid the construction of protective
structures such as sea walls and shoreline protection devices.
|
|
7
|
Where publicly owned storm drainage pipes run across a property
rendering it impossible to meet these minimum horizontal setback requirements,
the effluent dispersal system is allowed to be located within 50 feet
of the pipes provided that these pipes are positioned vertically higher
than the bottom of the effluent dispersal system or the applicant
demonstrates that the pipes are sealed so that there is no possibility
for shallow groundwater to infiltrate the storm drain.
|
|
8
|
"h" equals the height of cut or embankment, in feet. Where a
California certified engineering geologist and/or registered geotechnical
engineer finds and states in writing that the stability of the fill
or cut bank will not be compromised by a shorter horizontal separation
and that a shorter horizontal separation will not result in sewage
effluent daylighting, a shorter horizontal setback for the effluent
dispersal system can be used per the said geologist's recommendation.
|
|
9
|
Setback distance may be reduced in accordance with recommendations
provided in a geotechnical report prepared by a civil engineer or
professional geologist and addressed in the OWTS design report and
accompanying geotechnical report.
|
|
10
|
See California Plumbing Code, Section 720.0.
|
|
11
|
For parallel construction; for crossings, approval by the Health
Department shall be required.
|
F.
Flood
Hazard Areas. Disposal systems shall be located outside of flood hazard
areas.
Exception: Where suitable sites outside of flood hazard areas
are not available, disposal systems shall be permitted to be located
in flood hazard areas on sites where the effects of inundation under
conditions of the design flood are minimized.
(Ord. 435 § 3, 2018)
For all locations where an OWTS is proposed to be installed, site evaluations per the OWTS Manual shall be conducted prior to issuance of an OWTS construction permit to verify conformance with applicable soils, groundwater, horizontal setbacks, ground slope and other requirements as prescribed in Chapters 15.40 and 15.42 of the Malibu Municipal Code. In addition, the following reports and tests shall be submitted.
A.
OWTS
Design Report. The permit application for a new or replacement OWTS
installation shall include an OWTS design report prepared by a qualified
professional. The report shall summarize and integrate the results
of supporting geotechnical soils analyses and/or percolation tests,
system design specifications and site limitations and special characteristics,
as per the technical standards.
B.
Supporting
Geology Report. Site evaluation methods shall include soil profiles,
borehole and test pit logs, slope stability report if applicable,
and other exploratory tests, as necessary, to verify adequate depth
and permeability of soil, soil thickness, and vertical separation
between dispersal field and groundwater for both primary and reserve
dispersal areas. Information in the report shall include, but not
be limited to: soil conditions, characteristics and estimated permeability,
depth of zones of saturation, depth to bedrock, surrounding geographic
and topographic features, direction of ground contour and percent
slopes, distance to drainages, water bodies and potential for flooding.
Soils classification testing shall be conducted in accordance with
the technical standards contained in this code and guidelines provided
in the Malibu OWTS Manual and the results expressed in United States
Department of Agriculture classification terminology including descriptions
of both soil texture and soil structure. Soils classification for
engineering properties shall be conducted by a California registered
geotechnical engineer or a California registered civil engineer in
the environmental/geo-technical field.
C.
Percolation/Infiltration
Testing. Percolation tests shall be conducted by a California registered
geologist, a California registered geotechnical engineer, a California
registered civil engineer, or a California registered environmental
health specialist. Where the administrative authority has been provided
adequate evidence to demonstrate suitable soil conditions and groundwater
separation, testing requirements may be waived.
D.
Land
Division. For new divisions of land, soil profiles, percolation tests
and groundwater determinations will be required on every parcel unless
the administrative authority determines, on a case-by-case basis,
that such testing is not necessary due to the availability of sufficient
information to demonstrate conformance with applicable siting criteria
for all proposed OWTS locations.
(Ord. 435 § 3, 2018)
A.
General.
Daily wastewater flow estimates shall be established by the registered
OWTS designer for use in design, evaluation and monitoring of all
OWTS. Flow rates are used for sizing treatment unit capacity and sizing
of the dispersal system.
Single-Family Residences and Second Units. Wastewater flows
used for design of OWTS treatment capacity for single-family residences
and second units shall be based on the number of bedrooms in accordance
with criteria in Table 15.42.030(B)-1. The flow is calculated as 300
gallons per day for the first bedroom (master) and 150 gallons per
day for each additional bedroom. The design flows for a primary residence
and secondary dwelling unit shall be determined independently, regardless
of whether the flows are treated separately or combined in a single
OWTS.
|
Table 15.42.050(B)-1
Wastewater Design Flows for OWTS Treatment Units Serving Single-Family
Residences and Second Units
| |
|---|---|
|
No. of Bedrooms
|
Design Flow (gal/day)
|
|
1 (Master bedroom)
|
300
|
|
2
|
450
|
|
3
|
600
|
|
4
|
750
|
|
5
|
900
|
|
6
|
1,050
|
|
>6
|
+ 150 per bedroom
|
B.
Multiple
Dwelling Units. Wastewater flows used for the design of OWTS for multiple
residential units shall be based on the number of dwelling units in
accordance with criteria in Table 15.42.030(B)-2. The flow is calculated
as 300 gallons per day for the first bedroom (master) and 150 gallons
per day for each additional bedroom.
|
Table 15.42.050(B)-2
Wastewater Design Flows for OWTS Treatment Units Serving Multiple
Dwelling Units
| |
|---|---|
|
No. of Dwelling Units
(1 bedroom each)*
|
Design Flow (gal/day)
|
|
2
|
600
|
|
3
|
900
|
|
4
|
1,200
|
|
5
|
1,500
|
|
6
|
1,800
|
|
7
|
2,100
|
|
8
|
2,400
|
|
9
|
2,700
|
|
10
|
3,000
|
|
>10
|
+300 per unit
|
|
Notes:
| |
|---|---|
|
*
|
Extra bedrooms add 150 gallons each.
|
Commercial and Home Occupation Uses Described in Section
15.40.050(A)(1). Wastewater flows used for design of OWTS for uses
other than residential shall be estimated based on the projected activities,
occupancy, and facilities, using wastewater generation guidelines
provided in Table 15.42.030(B)-3. For facilities not listed in Table
15.42.030(B)-3 the wastewater design flow shall be estimated based
on either: (1) appropriate literature references (e.g., US EPA) for
the type of facility proposed; or (2) documented wastewater flow monitoring
data for no less than three comparable facilities. Additionally, the
administrative authority may consider adjustment to the criteria listed
in Table 15.42.030(B)-3 for specific facilities based upon documented
wastewater flow monitoring data. In all cases, the design proposal
shall include sufficient technical information to support the proposed
design flow estimate. Notwithstanding the above, minimum design flow
for any OWTS shall not be less than 150 gpd.
C.
|
Table 15.42.050(B)-3
Estimated Sewage/Waste Flow Rates
| |
|---|---|
|
Type of Occupancy
|
Design Flow (gal/day)
|
|
Airports
|
|
|
-Per employee
|
15
|
|
-Per passenger
|
5
|
|
Auto washers
|
Per equipment mfg.
|
|
Bowling alleys, snack bar only (per lane)
|
75
|
|
Camps (per person)
|
|
|
-With central comfort station
|
35
|
|
-With flush toilets, no showers
|
25
|
|
-Day camps, no meals served
|
15
|
|
-Summer and seasonal
|
50
|
|
Churches, sanctuary, religious halls (per seat)
|
|
|
-without kitchen
|
5
|
|
-with kitchen waste
|
7
|
|
Dance halls (per person)
|
5
|
|
Day care (per patron, employee)
|
15
|
|
Factories and industrial buildings (per employee)
|
|
|
-no showers
|
25
|
|
-with showers
|
35
|
|
-cafeteria, add
|
5
|
|
Hospitals
|
|
|
-per bed
|
250
|
|
-kitchen waste only (per bed)
|
35
|
|
-laundry waste only (per bed)
|
5
|
|
Hotels, no kitchen waste (per bed x 2)
|
60
|
|
Institutions (per person)
|
|
|
-resident
|
75
|
|
-nursing home
|
125
|
|
-rest home
|
125
|
|
Laundries, self-service
|
|
|
-minimum 10 hours per day (per wash cycle)
|
50
|
|
-commercial
|
Per manufacturer
|
|
Motel (per bed space)
|
|
|
-no kitchen
|
50
|
|
-with kitchen
|
60
|
|
Offices (per employee)
|
20
|
|
Parks
|
|
|
-mobile homes (per space)
|
250
|
|
-picnic parks, toilets only (per parking space)
|
20
|
|
-Recreational vehicles (per space)
|
|
|
• without water hook-up
|
75
|
|
• with water and sewer hook-up
|
100
|
|
Restaurants – cafeterias
|
|
|
-per seat
|
50*
|
|
-per employee
|
20
|
|
-toilet (per customer)
|
7
|
|
-kitchen waste (per meal
|
6
|
|
-add for cocktail lounge (per customer)
|
2
|
|
-kitchen waste – disposable service (per meal)
|
2
|
|
Schools
|
|
|
-staff and office (per person)
|
20
|
|
-elementary students (per student)
|
15
|
|
-intermediate and high (per student)
|
20
|
|
• with gym and showers
|
5
|
|
• with cafeteria, add
|
3
|
|
-boarding, total waste (per person)
|
100
|
|
Service station, toilets
|
3
|
|
-for 1st bay
|
1,000
|
|
-add for each additional bay
|
500
|
|
Stores
|
|
|
-per employee
|
20
|
|
-public restrooms, add per 10 ft2 of floor space
|
1
|
|
Swimming pools, public (per person)
|
10
|
|
Theaters
|
|
|
-auditoriums (per seat)
|
5
|
|
-drive-in (per space)
|
10
|
|
Notes:
| |
|---|---|
|
*
|
Number of seats shall be determined based on 15 square feet
per seat in service area.
|
D.
Flow
Equalization. Flow equalization is the process of controlling the
rate of wastewater flow through an OWTS by providing surge capacity
storage and timed-dosing of the incoming flow. It allows peak surges
in wastewater flow (e.g., from a weekend event) to be temporarily
stored and metered into the treatment system and/or dispersal field
at a relatively even ("average") rate over an extended number of days
(e.g., during the subsequent week). This process may be used for commercial
and multifamily systems as recommended by the OWTS designer.
(Ord. 435 § 3, 2018; Ord. 517, 6/24/2024)
Special design measures will be required for high strength wastewater
and other instances where it is determined by the administrative authority
that the quantity and/or quality of wastewater poses unusual treatment
or disposal challenges not addressed by conventional or advanced treatment
methods. These systems shall be subject to review and approval by
the administrative authority on a case-by-case basis. Examples include,
but are not limited to:
A.
Installations
where appreciable amounts of industrial or indigestible wastes are
produced;
B.
Occupancies
producing abnormal quantities of sewage or liquid waste;
C.
Where
grease interceptors are required by the California Plumbing Code;
or
D.
As
required by the Regional Water Quality Control Board.
(Ord. 435 § 3, 2018)
A.
General.
New and replacement OWTS septic tanks shall be limited to those approved
by the IAPMO or designed by a California registered civil engineer
to meet structural design standards acceptable to the administrative
authority, and their installation shall be according to the manufacturer's
instructions.
B.
Capacity.
The liquid capacity of all septic tanks shall conform to Table 15.42.070
as determined by: (1) the number of bedrooms or dwelling units; and
(2) the number of plumbing fixture units, whichever is greater. The
minimum total capacity of a septic tank shall be at least 1,500 gallons.
|
Table 15.42.070
Septic Tank Capacity
| |||
|---|---|---|---|
|
Single-Family Dwellings/Second Dwelling Units # of Bedrooms
|
Multiple Dwelling Units (1 bedroom each)
|
Maximum Drainage Fixture Units
|
Minimum Septic Tank Capacity4 (gallons)
|
|
1 to 61
|
2 to 3 units
|
33
|
1,500
|
|
-
|
4
|
45
|
2,000
|
|
-
|
5
|
55
|
2,250
|
|
-
|
6
|
60
|
2,500
|
|
-
|
7
|
70
|
2,750
|
|
-
|
8
|
80
|
3,000
|
|
-
|
9
|
90
|
3,250
|
|
-
|
102
|
1003
|
3,500
|
|
Notes:
| |
|---|---|
|
1
|
Additional bedrooms, 150 gallons each.
|
|
2
|
Additional dwelling units, 250 gallons each.
|
|
3
|
Additional fixture units over 100, 25 gallons per fixture unit.
|
|
4
|
Septic tank sizes in this table include sludge storage capacity
and the connection of domestic food waste disposal units without further
volume increase.
|
C.
Plans.
Plans for septic tanks shall be submitted to the administrative authority
for approval. Such plans shall show dimensions, reinforcing, structural
calculations, and such other pertinent data as required.
D.
Design.
Septic tank design shall be such as to produce a clarified effluent
consistent with accepted standards and shall provide adequate space
for sludge and scum accumulations.
E.
Compartments.
Septic tanks shall have not less than two compartments unless otherwise
approved by the administrative authority. The inlet compartment of
any septic tank shall be not less than two-thirds of the total capacity
of the tank, nor less than 1,000 gallons liquid capacity. The secondary
compartment of a septic tank shall have a capacity of not less than
500 gallons and a capacity not exceeding one-third of the total capacity
of such tank.
F.
Access
Manholes. Access to each septic tank shall be provided by at least
two manholes 24 inches (610 mm) in minimum diameter. One access manhole
shall be located over the inlet and one access manhole shall be located
over the outlet. Wherever a first compartment exceeds 12 feet (3,658
mm) in length, an additional manhole shall be provided over the baffle
wall. Septic tanks shall have the required manholes accessible by
extending the manhole openings to grade in a manner acceptable to
the administrative authority.
G.
Pipe
Opening Sizes. The inlet and outlet pipe openings shall not be larger
in size than the connecting sewer pipe. The vertical leg of round
inlet and outlet fittings shall not be less in size than the connecting
sewer pipe nor less than four inches (102 mm). A baffle-type fitting
shall have the equivalent cross-sectional area of the connecting sewer
pipe and not less than a four-inch (102 mm) horizontal dimension where
measured at the inlet and outlet pipe inverts.
H.
Pipe
Extension. The inlet and outlet pipe or baffle shall extend four inches
(102 mm) above and not less than 12 inches (305 mm) below the water
surface. The invert of the inlet pipe shall be at a level not less
than two inches (51 mm) above the invert of the outlet pipe.
I.
Free
Vent Area. Inlet and outlet pipe fittings or baffles and compartment
partitions shall have a free vent area equal to the required cross-sectional
area of the house sewer or private sewer discharging therein to provide
free ventilation above the water surface from the disposal field or
seepage pit through the septic tank, house sewer, and stack, or other
approved vent, to the outer air.
J.
Sidewalls.
The sidewalls shall extend not less than nine inches (229 mm) above
the liquid depth. The cover of the septic tank shall be not less than
two inches (51 mm) above the back vent openings.
K.
Partitions
and Baffles. Partitions or baffles between compartments shall be of
solid, durable material and shall extend not less than four inches
(102 mm) above the liquid level. The transfer port between compartments
shall be a minimum size equivalent to the tank inlet, but in no case
less than four inches (102 mm) in size, shall be installed in the
inlet compartment side of the baffle so that the entry into the port
is placed 65% to 75% in the depth of the liquid. Wooden baffles are
prohibited.
L.
Effluent
Filter. New and replacement OWTS septic tanks shall be designed to
prevent solids in excess of three-sixteenths of an inch in diameter
from passing to the dispersal system. Septic tanks that use a NSF/ANSI
Standard 46 certified septic tank effluent filter at the final point
of effluent discharge from the OWTS and prior to the dispersal system
shall be deemed in compliance with this requirement.
M.
Structural
Design. Septic tanks shall be constructed of solid durable materials
not subject to excessive corrosion or decay and shall be watertight.
The structural design of septic tanks shall comply with the following
requirements:
1.
Each
such tank shall be structurally designed to withstand all anticipated
earth or other loads. Septic tank covers shall be capable of supporting
an earth load of not less than 500 pounds per square foot (lb/ft2) (2441 kg/m2) where the
maximum coverage does not exceed three feet (914 mm).
2.
In
flood hazard areas, and in areas where the groundwater elevation is
above the tank bottom, tanks shall be anchored to counter buoyant
forces. The vent termination and service manhole of the tank shall
be not less than two feet (610 mm) above the design flood elevation
or fitted with covers designed to prevent the inflow of floodwater
or the outflow of the contents of the tanks during conditions of the
design flood.
3.
Traffic
Rated Tanks. Septic tanks must be structurally designed to withstand
all anticipated earth or other loads. Septic tanks located in traffic
areas, including driveways, shall be designed to a minimum H-20 traffic
ratings as established by the American Association of State Highway
Transportation Officials.
N.
Materials.
The materials used for constructing a septic tank shall be in accordance
with the following:
1.
Materials
used in constructing a concrete septic tank shall be in accordance
with applicable standards in the California Plumbing Code, Table 1401.1.
2.
Septic
tanks constructed of alternate materials may be approved by the administrative
authority where in accordance with approved applicable standards.
Wooden septic tanks shall be prohibited.
O.
Prefabricated
Septic Tanks. Prefabricated septic tanks shall comply with the following
requirements:
1.
Manufactured
or prefabricated septic tanks shall comply with approved applicable
standards and be approved by the administrative authority.
2.
Independent
laboratory tests and engineering calculations certifying the tank
capacity and structural stability shall be provided as required by
the administrative authority.
P.
Water-Tightness
Testing Requirements. All new septic tank installations and modifications
to existing septic tanks shall undergo water-tightness testing as
follows:
1.
New
Tanks. For new tank installations, the testing shall be done with
the access risers in place and the inlet and outlet pipes plugged.
The tank shall be filled with water to a level extending a minimum
of two inches into the risers, and monitored for a minimum one-hour
period, with no measurable drop in the water level.
2.
Existing
Tanks. For existing tanks, the tank shall be filled with water to
a level even with the invert of the outlet pipe, and monitored for
a one-hour period, with no measurable drop in water level. However,
in cases where there the groundwater level is known or estimated to
rise above the level of the outlet pipe during any time of the year,
the water-tightness test shall be conducted following the procedure
for new tank installations; i.e., by filling the tank with water into
the risers.
(Ord. 435 § 3, 2018)
A.
Interceptor.
Where liquid wastes contain excessive amounts of grease, garbage,
flammable wastes, sand, or other ingredients that affect the operation
of a OWTS, an interceptor for such wastes shall be installed as designed
by the OWTS designer.
B.
Installation.
Installation of such interceptors shall comply with the applicable
sections of the California Plumbing Code, and they shall comply with
the siting requirements for septic tanks contained in this code. The
administrative authority may require and approve additional more restrictive
standards.
C.
Sampling
Box. A sampling box shall be installed when required by the administrative
authority.
D.
Design and Structural Requirement. Interceptors shall be of an approved design and include at least two compartments unless otherwise approved by the administrative authority for good cause. Structural requirements shall be in compliance with the applicable requirements for septic tanks, per Section 15.42.070 of this chapter.
E.
Location.
Interceptors shall be located as close to the source of waste as possible
and be accessible for servicing. Manholes for servicing shall be at
grade level and be gastight.
F.
Waste
Discharge. Waste discharge from interceptors may be connected to a
septic tank or other OWTS component or be disposed into an approved
separate disposal system.
G.
Sizing
and Design Criteria. Systems shall be designed based on wastewater
flow rates from Table 15.42.050(B)-3 of this chapter and applicable
sections of the California Plumbing Code.
(Ord. 435 § 3, 2018)
A.
General.
1.
Supplemental
treatment to provide secondary (or better) effluent quality may be
provided by: (a) site-specific application of sanitary engineering
principles/methods (e.g., intermittent sand, aerobic bioreactors with
clarifiers); and/or (b) proprietary treatment units.
2.
Propriety
treatment units cover a category of manufactured or "package" systems
specifically developed for residential and other small-scale sewage
treatment applications. Most proprietary designs currently available
fall into the following categories: (a) aerobic treatment units (ATUs);
(b) media filters; and (c) fixed-film activated sludge units.
3.
Disinfection
units are an example of a supplemental treatment component providing
tertiary treatment, but only have applicability with secondary (or
better) effluent quality produced by a supplemental treatment unit
per subsection (A)(2) above.
4.
Effluent
from supplemental treatment units may be discharged to an approved
type of dispersal system, including conventional and pressure distribution
trenches or beds, chamber systems, subsurface drip dispersal fields,
seepage pits, or combinations thereof.
5.
Supplemental
treatment may be required as part of an advanced protection management
program in conformance with Statewide OWTS Policy Sections 10.9 and
10.10.
B.
Design
Requirements.
1.
General.
The OWTS designer and OWTS installer shall follow the proprietary
manufacturer's design, installation, construction, and operations
procedures, as applicable. All supplemental treatment systems shall
be operated in compliance with applicable design requirements particular
to the type of system, the facility served, and the site conditions
in compliance with the manufacturer requirements.
2.
Tanks
and Components.
a.
All tanks shall be structurally sound, watertight, operate in such
a manner as to not create odors or vector attraction, be properly
vented, and have a functional baffle(s).
b.
All components of the system shall be functional, in good working
order, and shall meet the design requirements for the specific site
conditions and application for which they are approved.
c.
Proprietary treatment units and components shall be structurally
sound, free from defects, be watertight, and not create odor or vector
attraction nuisance. The unit shall be operated in accordance with
the approved manufacturer and certification/listing organization standards.
C.
Sizing
and Design Criteria.
1.
Design
Wastewater Flow. Sizing and design of supplemental treatment units
shall be based on the projected wastewater flow for the building or
facility being served, determined in accordance with wastewater flow
requirements contained in this code.
2.
Tanks.
Sizing and design of tanks shall be in accordance with the structural
and volumetric capacity requirements of this code. All tanks housing
a proprietary treatment unit shall be structurally sound, watertight
and capable of withstanding anticipated loads and buoyant forces,
as applicable.
3.
Controls.
Control panels shall be designed and configured in such a manner that,
in the event of a treatment unit malfunction, an alarm system will
be triggered and discharge from the treatment system to the dispersal
field will be interrupted until the treatment unit malfunction is
rectified. At a minimum, the alarm system shall include an audible
and visual alarm at building served by the system.
4.
Emergency
Storage Provisions. Where a supplemental treatment unit is used in
conjunction with a non-gravity fed dispersal system, the system shall
provide emergency storage capacity equal to at least the daily wastewater
flow (in gallons) or provide an audible and visible alarm with a telemetry
connection to the registered maintenance provider.
5.
Compliance
with Manufacturer Requirements. The design shall follow the proprietary
manufacturer's design, installation, construction, and operations
procedures, as applicable.
(Ord. 435 § 3, 2018)
A.
General.
The construction dimensions of the subsurface sewage effluent disposal
area of an onsite wastewater treatment system shall be based on soils
analysis and/or percolation tests. Soils analysis shall be conducted
by a licensed soils engineer and the results expressed in United States
Department of Agriculture classification terminology. Percolation
tests shall be conducted by a California registered professional geologist,
a California registered civil engineer, or a California registered
environmental health specialist. Specific methodologies for these
tests are provided in the Malibu OWTS Manual and design criteria listed
below.
B.
Sizing
and Design Criteria.
1.
Minimum
Effective Absorption Area. The minimum effective absorption area required
shall be sufficient for absorption of the daily quantity of liquid
waste discharging into the dispersal system, determined by either:
(a) the required septic tank capacity in gallons (liters); and/or
(b) the estimated daily waste/sewage flow, whichever is greater.
2.
Absorption
Capacity. The absorption capacity of disposal trenches and beds shall
be based on the effective absorption area and the percolation characteristics
of the underlying and surrounding soil, as determined from results
of field percolation testing and design criteria. Present and future
dispersal areas must be tested.
3.
Effective
Absorption Area. The effective absorption area of a disposal trench
shall normally be calculated as the bottom width. Sidewall area in
excess of the required 12 inches (305 mm) and not exceeding 36 inches
(914 mm) below the leach line shall be permitted to be added to the
trench bottom area where computing absorption areas.
4.
Leaching
Beds. Where leaching beds are permitted in lieu of trenches, the area
of each such bed shall be not less than 50% greater than the requirements
for trenches. Perimeter sidewall area in excess of the required 12
inches (305 mm) and not exceeding 36 inches (914 mm) below the leach
line shall be permitted to be added to the trench bottom area where
computing absorption areas.
5.
Leaching
Chambers. Leaching chambers shall be sized on the bottom absorption
area (nominal until width) in square feet with no reduction in sizing
less than 30%.
C.
Construction.
Disposal fields shall be constructed in accordance with Table 15.42.100
Disposal fields shall not be installed in uncompacted fill.
|
Table 15.42.100
General Disposal Field Requirements
| ||
|---|---|---|
|
Item
|
Minimum
|
Maximum
|
|
Number of drain lines per field
|
1
|
-
|
|
Length of each line
|
-
|
100 feet
|
|
Bottom width of trench
|
18 inches
|
36 inches
|
|
Spacing of lines, center-to-center
|
6 feet
|
-
|
|
Depth of earth cover of lines
|
12 inches
|
-
|
|
Grade of lines
|
Level
|
3 inches per 100 feet
|
|
Filter material under drain lines
|
121 inches
|
-
|
|
Filter material over drain lines
|
2 inches
|
-
|
D.
Distribution
Lines. Distribution lines shall be constructed of perforated ABS pipe,
perforated PVC pipe, or other materials approved by the administrative
authority, provided that sufficient openings are available for distribution
of the effluent into the trench area.
E.
Grade
Board. A grade board staked in the trench to the depth of filter material
shall be utilized when the distribution line is constructed of material
which will not maintain alignment without continuous support.
F.
Distribution
Boxes. Where two or more drain lines are installed, an approved distribution
box of sufficient size to receive lateral lines shall be installed
at the head of each disposal field. The inverts of outlets shall be
level, and the invert of the inlet shall be not less than one inch
(25.4 mm) above the outlets. Distribution boxes shall be designed
to ensure equal flow and shall be installed on a level concrete slab
in natural or compacted soil.
G.
Laterals.
Laterals from a distribution box to the disposal field shall be approved
pipe with watertight joints. Multiple disposal field laterals, where
practicable, shall be of uniform length.
H.
Connections.
Connections between a septic tank and a distribution box shall be
laid with approved pipe with watertight joints on natural ground or
compacted fill.
I.
Spacing.
1.
Minimum
spacing between trenches or leaching beds shall be not less than four
feet (1,219 mm) plus two feet (610 mm) for each additional foot (305
mm) of depth in excess of one foot (305 mm) below the bottom of the
drain line.
2.
Distribution
drain lines in leaching beds shall be not more than six feet (1,829
mm) apart on centers, and no part of the perimeter of the leaching
bed shall exceed three feet (914 mm) from a distribution drain line.
3.
When
seepage pits are used in combination with disposal fields, the filter
material in the trenches shall terminate at least five feet (1,524
mm) from the seepage pit excavation.
J.
Surface
Covering. Disposal fields, trenches, and leaching beds shall not be
paved over or covered by concrete or a material that is capable of
reducing or inhibiting a possible evaporation of sewer effluent. Exceptions
may be approved by the administrative authority for site with sand
soil type and alternate ventilation design.
K.
Joints.
Where necessary on sloping ground to prevent excessive line slope,
leach lines or leach beds shall be stepped. The lines between each
horizontal section shall be made with watertight joints and shall
be designed so each horizontal leaching trench or bed shall be utilized
to the maximum capacity before the effluent shall pass to the next
lower leach line or bed. The lines between each horizontal leaching
section shall be made with approved water-tight joints and installed
on natural or unfilled ground.
L.
Dosing
Tanks. Where approved by the administrative authority, dosing tanks
used in conjunction with an OWTS may be used. Automatic siphon or
dosing tanks shall be installed when required or as permitted by the
administrative authority.
(Ord. 435 § 3, 2018)
A.
General.
The construction dimensions of the subsurface sewage effluent disposal
area of an onsite wastewater treatment system utilizing seepage pits
shall be based on soils analysis and percolation tests. Soils analysis
shall be conducted by a licensed soils engineer and the results expressed
in United States Department of Agriculture classification terminology.
Percolation tests shall be conducted by a licensed geologist, a licensed
soils engineer, a licensed civil engineer, or a California registered
environmental health specialist. Specific methodologies for these
tests are provided in the Malibu OWTS Manual and design criteria listed
below.
B.
Sizing
and Design Criteria.
1.
Effective
Absorption Area. The effective absorption area of any seepage pit
shall be calculated as the excavation sidewall area in square feet
(ft2) below the inlet, excluding impermeable
soil zones where identified during field exploration.
2.
Absorption
Capacity. The absorption capacity of seepage pits shall be based on
the effective absorption area per effective absorption area requirements
and the percolation characteristics of the surrounding soil, as determined
from results of field percolation testing and design criteria. Present
and future dispersal areas must be tested.
3.
Minimum
Effective Absorption Area. The minimum effective absorption area required
shall be sufficient for absorption of the daily quantity of liquid
waste discharging into the dispersal system, based on either: (a)
the required septic tank capacity in gallons (liters); and/or (b)
the estimated daily waste/sewage flow, whichever is greater.
4.
Multiple
Pits and Disposal Combinations. The minimum required absorption area
may be provided in one or more seepage pits or in combination with
other dispersal methods, e.g., trenches, beds or subsurface drip dispersal.
C.
Multiple
Installations. Multiple seepage pit installations shall be served
through an approved distribution box. Distribution boxes shall have
their locations permanently marked with a steel post, concrete marker
or other durable material. Additionally, each distribution box shall
have an inspection riser of white PVC or concrete of at least eight
inches in diameter. The inspection riser shall allow inspection access
to the distribution box. Each riser shall terminate with an approved
screw type cap.
D.
Construction.
Each seepage pit shall be circular in shape and shall have an excavated
diameter of not less than four feet (1,219 mm). Approval shall be
obtained prior to construction for any pit having an excavated diameter
greater than six feet (1,829 mm). Seepage pits shall not be installed
in uncompacted fill.
F.
Lining.
Seepage pits may be constructed in one of two ways, as follows:
1.
An
eight-inch (204 mm) white, or other similar approved color, sewer
pipe of approved material shall be installed true and plumb in the
center of the seepage pit excavation extending from the bottom of
the seepage pit excavation to the inlet depth. The sewer pipe shall
have one-inch (25.5 mm) holes drill each 120 degrees of the sewer
pipe circumference at 12 inch (306 mm) intervals on center minimum
for the entire length of the sewer pipe to the inlet depth. The sewer
pipe shall then extend watertight to grade and shall be capped with
an approved screw type, accessible cap. The void between the sewer
pipe and the seepage pit excavation shall then be filled with clean
stone, gravel, or similar filter material acceptable to the administrative
authority, varying in size from three-fourths inch to two and one-half
inches (19.1 mm to 64 mm).
2.
Pre-cast
concrete circular sections approved by the administrative authority
may be used. The void between the pre-cast circular sections and the
seepage pit excavation shall have a minimum of six inches (152 mm)
of clean three-fourths inch (19.1 mm) gravel or rock filter material.
An approved type one- or two-piece reinforced concrete slab cover
shall be installed on top of the pre-cast concrete circular sections.
Each such cover shall have 2,500 pounds per square inch (17,238 kPa)
minimum compressive strength shall be not less than five inches (127
mm) thick and shall be designed to support an earth load of not less
than 400 pounds per square foot (19.2 kPa). Each such cover shall
be provided with an eight-inch (204 mm) minimum inspection hole and
shall be coated on the underside with an approved bituminous or other
nonpermeable protective compound. An eight-inch (204 mm) white, or
similar approved color, sewer pipe of approved material shall be installed
true and plumb extending watertight from the cover inspection hole
to grade and shall be capped with an approved accessible cap.
G.
Sidewall.
A seepage pit shall have a minimum side-wall of 10 feet (3,048 mm)
below the inlet.
H.
Cover.
The cover/cap of a seepage pit shall be constructed and located as
follows:
1.
Approved-type
one- or two-piece reinforced concrete slabs of not less than 2,500
lb/in2 (1,757,674 kg/m2) minimum compressive strength, not less than five inches (127 mm)
thick, and designed to support an earth load of not less than 400
pounds per square foot (lb/ft2) (1,953
kg/m2). Each such cover shall be provided
with a nine-inch (229 mm) minimum inspection hole with plug or cover
and shall be coated on the underside with an approved bituminous or
other nonpermeable protective compound.
2.
Cap
depth of the seepage pit (distance from the surface of the ground
to the top of the effective portion of the seepage pit) shall be specified
by the engineering geologist and incorporated as part of the OWTS
design.
I.
Inlet
Fitting. An approved vented inlet fitting shall be provided in the
seepage pit so arranged as to prevent the inflow from damaging the
sidewall.
Exception: Where using a one- or two-piece concrete slab cover
inlet, the fitting shall be permitted to be a one-fourth bend fitting
discharging through an opening in the top of the slab cover. On multiple
seepage pit installations, the outlet fittings shall comply with subsection
(H)(1) of this section.
(Ord. 435 § 3, 2018)
A.
General.
Pressure distribution systems are a variation of a conventional disposal
field system that use a pump and small-diameter pressure piping to
achieve broad, uniform distribution of wastewater throughout the dispersal
field for improved soil absorption and better treatment of percolating
effluent. Pressure distribution can be used in conjunction with rock-filled
trenches or leaching chamber dispersal fields, receiving either septic
tank effluent or secondary/tertiary effluent from a supplemental treatment
unit. Pressure distribution is not used with seepage pits. Specific
methodologies for siting and design of these systems are provided
in the Malibu OWTS Manual and the design criteria listed below.
B.
Applications.
Pressure distribution may be incorporated in any leaching trench/bed
disposal field, and is required for the following situations:
1.
Areas
with ground slopes between 30 to 45%, in conjunction with supplemental
treatment;
2.
Areas
with percolation rates of less than five mpi or greater than 60 mpi,
in conjunction with supplemental treatment;
3.
Beachfront
properties;
4.
To
allow reduction of minimum vertical separation to groundwater (below
trench bottom) from five feet to three feet or two feet for beachfront
properties, in conjunction with supplemental treatment;
5.
For
large flow systems, e.g., with dispersal field lengths exceeding 500
lineal feet;
6.
Disposal
fields with non-uniform lateral lengths or irregular (non-rectangular)
shapes; and
7.
Situations
as may be determined necessary due to site-specific soil, geology
or other conditions.
C.
Siting
Criteria.
1.
Setbacks.
Horizontal setback requirements for pressure distribution trench systems
shall be those applicable to conventional dispersal fields.
2.
Vertical
Separation Requirements.
a.
Depth to Groundwater. Minimum depth to seasonal high groundwater
for pressure distribution trench systems, as measured from trench
bottom, shall be three feet.
b.
Soil Depth. Minimum depth of soil, as measured from trench bottom
to impermeable soil or rock, for pressure distribution trench systems
shall be three feet.
3.
Percolation
Rate. Average percolation rate for pressure distribution trench systems
shall be within the range of one mpi to 120 mpi, as determined in
accordance with standard percolation requirements for conventional
dispersal trenches.
4.
Ground
Slope. Maximum ground slope in areas used for pressure distribution
systems shall be 45%. An evaluation of the disposal area shall be
included in a slope stability report.
D.
Sizing
and Design Criteria.
1.
Wastewater
Treatment. Pressure distribution trench systems may be used for dispersal
effluent that has received supplemental treatment (secondary or better),
using an approved advanced treatment system.
2.
Sizing.
Pressure distribution trench systems shall be sized by percolation
rates in the same manner as conventional dispersal trenches, according
to requirements in this code and the Malibu OWTS Manual.
3.
Pressure
Dosing. Septic tank effluent shall be applied to the pressure distribution
trench system by pressure dosing, utilizing a pump system or automatic
dosing siphon. The pressure distribution system shall be designed
in accordance with accepted engineering practices to achieve, at a
minimum:
a.
Uniform dosing of wastewater effluent throughout the system of pressure
distribution trenches;
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; and
d.
Dosing volume to achieve minimum of three to five doses per day at
design flow conditions.
4.
Pump
System or Dosing Siphon. The pump system or dosing siphon, as applicable,
shall be: (a) appropriate for sewage applications; (b) of the size
and type to meet hydraulic design requirements consistent with engineering
practice; and (c) designed and constructed in accordance with pump
system/dosing siphon requirements provided in the Malibu OWTS Manual.
E.
Construction
and Materials.
1.
Dispersal
Trenches. Pressure distribution trenches shall conform to the same
design and construction requirements as conventional trench requirements
contained in this code, with the exception that the piping system
shall consist of pressure piping rather than gravity piping and non-uniform
lateral lengths and nonuniform disposal field dimensions shall be
permitted.
2.
Pressure
Distribution Piping.
a.
Pressure-Rated Pipe Material. All pipe, fittings and valves shall
be pressure-rated PVC pipe, minimum 150 psi.
b.
Solvent Welded. All joints in the pressure piping system shall be
solvent welded.
c.
Pipe Sizing. All pressure distribution pipes and fittings, including
transport lines, manifolds, laterals and valves, must be adequately
sized for the design flow, and shall be designed to minimize frictional
losses to the maximum extent practicable.
d.
Thrust Blocks. Concrete thrust blocks, or equivalent restraint, shall
be provided at sharp changes in piping directions.
e.
Shut-Off Valves. The distribution lateral for each trench shall be
fitted with a shut-off valve to adjust or terminate the flow to individual
trenches. This valve may be either a ball or gate valve, and shall
be located in a utility/valve box.
f.
Lateral End Riser. The end of each lateral shall be fitted with a
90 degree long sweep to facilitate line cleaning and hydraulic testing.
The end riser pipe shall also be fitted with a ball valve and/or threaded
end cap or plug, housed in a valve box.
(Ord. 435 § 3, 2018)
A.
General.
Subsurface drip dispersal is a method for disposal of treated wastewater
that uses special drip tubing designed for use with wastewater. The
dripline is placed nine to 12 inches below ground surface and makes
use of the most biologically active soil zone for distribution, nutrient
uptake and evapotranspiration of the wastewater. A drip dispersal
system is comprised of small-diameter (one-half-inch to one-inch)
laterals ("driplines"), spaced 24 inches apart, with small-diameter
emitters (one-eighth-inch) located at 12 to 24 inches on-center along
the dripline. Effluent is conveyed under pressure to the laterals,
with timed doses. Prior to dispersal the effluent requires supplemental
treatment.
B.
Applications.
Subsurface drip dispersal may be incorporated into the OWTS design
for the following situations:
1.
Areas
with ground slopes between 30 to 45%;
2.
Areas
with percolation rates of less than five mpi or greater than 60 mpi;
3.
To
allow reduction of minimum vertical separation to groundwater (below
trench bottom) from five feet to three feet;
4.
To
allow reduction of horizontal setbacks as approved by the administrative
authority; and
5.
Situations
as may be determined necessary due to site-specific soil, geology
or other conditions with approval from the administrative authority.
C.
Siting
Criteria.
1.
Setbacks.
Horizontal setback requirements for drip dispersal systems shall be
those applicable to conventional dispersal fields, as specified in
this code or as otherwise approved by the administrative authority.
2.
Vertical
Separation Requirements.
a.
Depth to Groundwater. Minimum depth to seasonal high groundwater
for drip dispersal systems, as measured from the dripline, shall be
two feet.
b.
Soil Depth. Minimum depth of soil, as measured from bottom of dripline
to impermeable soil or rock, for drip dispersal systems shall be five
feet, unless otherwise approved by the administrative authority.
3.
Ground
Slope. Maximum ground slope in areas used for drip dispersal systems
shall be 45%. An evaluation of the disposal area shall be included
in a slope stability report.
D.
Sizing
and Design Criteria.
1.
Wastewater
Treatment.
a.
Wastewater effluent discharged to any drip dispersal system shall
be treated with an approved supplemental treatment system, in accordance
with applicable sections of this code.
b.
All drip dispersal systems shall include a filtering device capable
of filtering particles larger than 100 microns; this device shall
be located downstream of the supplemental treatment system.
c.
Additional requirements may be assigned in connection with criteria
for use in advanced protection management areas.
2.
Dripfield
Sizing.
a.
Wastewater Design Flow. Drip dispersal systems shall be designed to accept the design wastewater flow for the building or facility being served, determined in accordance with wastewater flow requirements contained in Section 15.42.050.
b.
Wastewater Application Rates. Wastewater application rates used for
sizing drip dispersal fields shall be based on either: (i) soil percolation
rate determined in accordance with methods described in the Malibu
OWTS Manual; or (ii) soil classification with hydraulic loading rates
found in the 2002 USEPA Manual as depicted in Table 15.42.100. In
applying these criteria, the wastewater application area refers to
the ground surface area encompassed by the drip dispersal field.
c.
Dripfield Area. Minimum sizing of the dripfield area shall be equal
to the design wastewater flow divided by the applicable wastewater
application rate from subsection (D)(2)(b) of this section.
d.
Drip Emitter Coverage. For sizing purposes, effective ground surface
area used for drip field sizing calculations shall be limited to no
more than four square feet per drip emitter. For 200 lineal feet of
dripline with emitters at two-foot spacing would provide a total of
100 emitters (200/2) and could be used for dispersal to an effective
area of up to 400 ft2 (100 emitters x 4
ft2/emitter). Conversely, if wastewater
flow and percolation/soils design information indicate the need for
an effective area of 1,000 ft2, the dripline
design and layout would have to be configured to provide a minimum
of 250 emitters spaced over the required 1,000 ft2 of dispersal area.
e.
Dripfield Zones. Dripfields may be divided into multiple zones which
may be located in different areas of a site, as desired or needed
to provide the required dripfield size. A single continuous dripfield
area is not required. However, any areas proposed for drip dispersal
shall be supported by field observations and measurements to verify
conformance with soil suitability and other site requirements. Differences
in soil conditions and percolation characteristics from one zone to
another may require the use of correspondingly different wastewater
application rates and dripfield sizing for each zone.
|
Table 15.42.130
Wastewater Application Rates for Subsurface Drip Dispersal Fields
(Adapted from 2002 USEPA Manual Table 4.3)
| ||
|---|---|---|
|
Soil Texture
|
Structure
|
Application Rate
(gpd/sf)
|
|
Gravelly coarse sand & coarser
|
Loose or cemented
|
0.0
|
|
Clay, sandy or silty clay silt loam
|
Weak or massive
|
0.0
|
|
Massive
|
0.0
| |
|
Sandy clay loam, clay loam or silty clay loam
|
Massive
|
0.0
|
|
Sandy clay, clay or silty clay
|
Moderate to strong
|
0.2
|
|
Sandy clay loam, clay loam or silty clay loam
|
Weak
|
0.2
|
|
Sandy clay loam, clay loam or silty clay loam
|
Moderate to strong
|
0.4
|
|
Sandy loam, loam or silt loam
|
Weak
|
0.4
|
|
Sandy loam, loam or silt loam
|
Moderate to strong
|
0.6
|
|
Fine, very fine, loamy fine and very loamy fine sand
|
Not Applicable
|
0.8
|
|
Coarse, single grain sand
|
Not Applicable
|
1.2
|
3.
Pressure
Dosing. Secondary-treated effluent shall be delivered to the dripfield
by pressure, employing a pump system and timed dosing. The pressure
distribution system shall be designed in accordance with accepted
engineering practices and manufacturer recommendations for drip dispersal
systems to achieve, at a minimum:
a.
Uniform dosing of treated effluent;
b.
An adequate dosing volume and pressure per manufacturer's guidelines;
c.
Adequate flow rate, final filtering of effluent and suitable piping
network to preclude solids accumulation in the pipes and driplines
or clogging of discharge emitters;
d.
A means of automatically flushing the filter and driplines at regular
intervals; and
e.
Suitable access provisions for inspection, testing and adjustment
of the dripfield and components.
f.
As applicable, additional requirements for design and construction
of pressure distribution piping systems specified for "pressure distribution
systems" in this code shall also apply.
E.
Construction
and Materials.
1.
Dripline
Material. Dripline shall be manufactured and intended for use with
secondary quality wastewater, with minimum 45 mil tubing wall thickness,
bacterial growth inhibitor(s), and means of protection against root
intrusion.
2.
Dripfield
Layout. The bottom of each dripline row shall be level and parallel
to the slope contour.
3.
Dripline
Depth. The dripline depth shall be installed at a minimum depth of
12 inches below grade and must be continuously covered by a minimum
depth of 12 inches of soil/mulch. Deeper placement of driplines may
be considered on a case-by-case basis.
4.
Length
of Individual Driplines. The maximum dripline length shall be designed
in accordance with accepted engineering practices and in accordance
with the manufacturer's criteria and recommendations.
5.
Line
and Emitter Spacing. Line and emitter spacing shall be designed as
appropriate for soil conditions, slope, and contour. There shall be
a minimum spacing of 12 inches between emitters and no emitter shall
be located less than 12 inches from the supply and return manifolds.
(Ord. 435 § 3, 2018)
A.
General.
All proposed OWTS on beachfront properties shall be designed and installed
in accordance with this code and city coastal engineering requirements
and shoreline protection requirements. Beachfront development that
includes new OWTS or expansion of existing OWTS shall include secondary
treatment with disinfection of effluent prior to discharging to any
subsurface disposal system. Seepage pits shall not be allowed unless
otherwise approved by the administrative authority for good cause.
B.
Siting
Criteria.
1.
Setbacks.
Horizontal setback requirements for beachfront OWTS shall be the same
as those applicable to conventional dispersal fields as specified
in this code and criteria contained in the Malibu OWTS Manual, or
as otherwise approved by the administrative authority for good cause.
2.
Vertical
Separation Requirements.
a.
Depth to Tidal Water and soil. The bottom of any leach trench or
drainfield shall have a minimum of two feet temporary (seasonal) clearance
and four feet (annual average) permanent clearance above the mean
high tide elevation, saturated zone or impervious soil or rock as
applicable.
b.
Depth to Groundwater. Minimum depth to seasonal high groundwater,
as measured from trench bottom, shall be five feet or as otherwise
approved by the administrative authority for good cause.
C.
Sizing
and Design Criteria. The dispersal system shall be sized and designed
in the same manner as pressure distribution systems, according to
requirements in this code and the Malibu OWTS Manual. Effluent dispersal/disposal
capacity shall be based on sand category design, for hydraulic loading.
1.
Wastewater
Treatment. Beachfront development that includes new OWTS or expansion
of existing OWTS shall include secondary treatment with disinfection
of effluent.
2.
Shoreline
Protection Devices. For new OWTS or expansion of existing OWTS, all
system components shall be protected from tidal and wave uprush action
by a shoreline protection device adequately designed and engineered
by a state of California licensed civil engineer specializing in coastal
engineering. Existing shoreline protection devices must provide protection
greater than or equal to current coastal engineering standards or
shall be modified to meet this code. The minimum horizontal distance
between and portion of the OWTS and shoreline protection device, including
returns shall not be less than five feet, or as otherwise approved
by the administrative authority for good cause.
3.
Vertical
Clearance. The space above the OWTS shall have a minimum of six feet
vertical clearance to the bottom of any structural element including
any cover such as stucco or wood siding. The required clearance shall
be maintained overall system components and shall extend horizontally
to the open ocean side of the building with no obstructions other
than shoreline protection devices.
4.
Access.
No portion of the OWTS shall be located under any portion of any structure
whether covered or uncovered except as approved in conformance with
criteria contained in the OWTS Manual or by the administrative authority
for good cause. OWTS shall have adequate access and clearances for
the purposes of system maintenance and repair without the removal
of any permanent structures, landscaping or other similar obstructions
to access the system.
(Ord. 435 § 3, 2018)
A.
General.
Construction and inspection of OWTS shall comply with the following:
1.
Applicable
provisions of the Malibu Municipal Code related to inspections for
construction permits shall be required. Approved OWTS plans shall
be required to be available for review at the construction site during
inspections.
2.
System
components shall be labeled to identify the manufacturer. Septic tanks
or other components of the OWTS shall have the rated capacity permanently
marked on the unit.
3.
Septic
tanks and other components of the OWTS shall be installed as required
by the administrative authority and manufacturer requirements.
4.
The
dispersal system shall be installed at the same location and depth
as shown on approved plans.
5.
Construction inspections by the project engineering geologist and OWTS designer shall be conducted as required by the qualified professional, as defined in Malibu Municipal Code Chapter 5.38, or administrative authority.
6.
Flow
Test. As part of the inspection a flow test shall be performed through
the system to the point of effluent disposal. All lines and components
shall be watertight as applicable. Capacities, required air space,
fittings and performance requirements shall comply with the provisions
set forth in these standards.
B.
Leach
Trenches/Beds. Filter Material. Before placing filter material or
drain lines in a prepared excavation, all smeared or compacted surfaces
shall be removed by raking to a depth of one inch (25.4 mm) and the
loose material removed. Clean stone, gravel, slag, or similar material
acceptable to the administrative authority, varying in size from three
fourths inch to two and one-half inches (19.1 mm to 64 mm) shall be
placed in the trench to the depth and grade required by this section.
Drain pipe shall be placed on the filter material in an approved manner.
The drain lines shall then be covered with filter material to the
minimum depth required by this section and covered with material approved
by the administrative authority to prevent closure of voids with earth
backfill. No earth backfill shall be placed over the filter material
until after inspection and acceptance.
Exception: Plastic leaching chambers approved by the administrative
authority may be used in lieu of pipe and filter material. Chamber
installations shall follow the rules for disposal fields, where applicable,
and shall conform to manufacturer's installation instructions.
C.
Seepage
Pits.
1.
Seepage
pits shall be located in accordance with the approved plot plan or
as otherwise approved by the administrative authority for good cause.
2.
All
seepage pits shall be fed through effluent laterals which are connected
to a distribution box. No seepage pits shall be installed in series.
3.
Filter
material, when used, is to be two- to two-and-one-half-inch washed
gravel. The filter material should not contain fine materials. The
installer must demonstrate the gravel is washed by submittal of documentation
from supplier or other approved means. Failure to comply may result
in rejection of the seepage pit installed.
4.
The
effluent line installed within the seepage pit shall be a minimum
eight-inch white (or similar approved color) PVC Schedule 40 or SDR
35 piping installed true and plumb. The effluent line shall have holes
drilled each 120 degrees of the pipe circumference at 12 inches on
center minimum for the entire length of the seepage pit below the
inlet. The riser will extend flush with the surrounding ground or
above and shall not be diminished in size. The riser shall be capped
with an approved cap and must remain accessible at all times.
5.
Lined
seepage pits shall be allowed when approved by the administrative
authority and comply with Section H 701.0 of the California Plumbing
Code.
D.
Pressure
Distribution Trench Systems. At a minimum, inspection of the pressure
distribution trench system installation shall include the items listed
below. This is in addition to inspection work required for a supplemental
treatment system, if used. Joint inspection by the OWTS designer,
contractor, and administrative authority may be required.
1.
Pre-construction
inspection where the construction staking or marking of the supply
and return piping, pump system and appurtenances is provided and construction
procedures discussed;
2.
Water
tightness of septic tank and dosing (pump) tank;
3.
Pipe
or drip field layout, piping materials and installation, and all associated
valves and connections;
4.
Hydraulic
testing of the pressure pipe system;
5.
Functioning
and setting of all control devices; and
6.
Final
inspection to verify that all construction elements are in conformance
with the approved plans and specifications, and operation and maintenance
guidelines/manual are provided to owner.
E.
Drip
Dispersal Systems. At a minimum, inspection of the drip dispersal
system installation should include the items listed below. This is
in addition to inspection work required for a supplemental treatment
system, if used. Joint inspection by the OWTS designer, contractor,
and administrative authority may be required.
1.
Pre-construction
inspection where the construction staking or marking of the drip lines,
supply and return piping, pump system and appurtenances is provided
and construction procedures discussed;
2.
Water
tightness of septic tank and dosing (pump) tank;
3.
Drip
field layout, piping materials and installation, and all associated
valves and connections;
4.
Hydraulic
testing of the drip system;
5.
Functioning
and setting of all control devices; and
6.
Final
inspection to verify that all construction elements are in conformance
with the approved plans and specifications, erosion control has been
completed; and operation and maintenance guidelines/manual are provided
to owner and administrative authority.
F.
Tanks.
Septic tanks and other OWTS vessels shall be filled with water to
flow line and piping as applicable prior to requesting inspection.
Seams or joints shall be left exposed (except the bottom), and the
tank shall remain water-tight.
G.
Supplemental
Treatment Units. The following minimum inspections prior to commencing
construction or covering any elements of the system shall be required.
Joint inspection by the OWTS designer, OWTS installer, and administrative
authority may be required.
1.
Pre-construction
inspection where the construction staking or marking of the treatment
unit is to be placed and installation procedures are discussed;
3.
At
final inspection completion and acceptance form signed/stamped by
the OWTS designer, OWTS installer, OWTS operation and maintenance
provider attesting that the treatment unit has been installed and
is operating in conformance with design specifications shall be provided.
(Ord. 435 § 3, 2018)
