HomeMy WebLinkAbout12-135RESOLUTION ADOPTING UPDATES TO ON-SITE WASTEWATER MANUAL
WHEREAS, the science and technology of wastewater treatment, dispersal, and management is rapidly changing
and advancing; and
WHEREAS, practices, procedures, and interpretations of wastewater requirements adopted by the Board need to
be continually evaluated so that the public needs are met in the most user-friendly and cost-effective means possible, and
WHEREAS, Butte County Code Chapter 19 recognized this need for continual quality improvement by
establishing an On-Site Wastewater Manual setting forth parameters for the application and use of wastewater technology;
and
WHEREAS, Butte County Code Chapter 19 established the Wastewater Advisory Committee to assist in the
development and future revision of the On-Site Wastewater Manual in order to provide continual quality improvement;
and
WHEREAS, the Wastewater Advisory Committee has recommended certain updates to the On-Site Wastewater
Manual to reduce the required setback between septic tanks and drainfields and wells supplying water for public water
systems and to establish wastewater system standards for system repairs.
NOW, THEREFORE, SE IT RESOLVED that the Board of Supervisors of the County of Butte hereby adopts
the changes to the On-Site Wastewater Manual as set forth in Exhibit A.
PASSED AND ADOPTED this 11th day of December, 2012, by the following votes:
AYES: Supervisors Connelly, Wahl, Kirk, Yamaguchi and Chair Lambert
NOES: None
NOT VOTING: None
ABSENT: None
AT7
PA[
and
By:
~~~~
STEVE LA RT, Chair
Butte County Board of Supervisors
Exhibit A
Revisions to On-Site Wastewater Manual Part 3 System Requirements
Chapter 2. Location and Setbacks
The setbacks shown in the following table will apply to all on-site wastewater
systems unless otherwise specified in this Manual.
Minimum Horizontal Separation
From Septic Tank,
From Disposal
Distance Required From: ATU, or Lined Sand
Field
Filter
Wells
Public well 100' 100'
Private well 100' 50'
Other wells, excluding monitoring wells 100' 50'
Surface waters
Reservoirs or lakes 200' 50'
Year-Round Springs, Streams, Creeks, or
Ponds 100' 50'
Intermittent streams, drainage swales 50' 50'
Curtain drains--Vertical/Curtain drains
Up gradient of system 20' 20'
Down radient of s stem 50' 25'
Cuts manmade in excess of 2.5 feet (top of down 4 X height of the bank, 20'
slope cut) or escarpments to a maximum of 50'
Property lines, foundation lines of any structure
including garages, out-buildings, in-ground swim 5' 5'
pools, water linesa.s
Easements
Public access easement 20' 20'
Other easement Clear Clear
Table Footnotes
If a setback is not specified in this Table, the most recent Uniform Plumbing Code setback adopted by the Board of
Supervisors will be applied.
1 Additional setback may be required from dispersal field for community or larger wastewater systems
2 Setbacks from streams and creeks must be measured from bank drop-off or mean yearly high water
mark; reservoirs and lakes are differentiated from ponds by being greater than 1 acre-feet in size;
landscape ponds less than 5,000 gallons are exempt from these setbacks.
3 The height (in feet) of the cut or escarpment as measured from the toe of the cut or vertically to the
projection of the natural ground slope.
4 The LEA encourages the placement of septic tanks and other treatment units as close as feasible to
the minimum separation from the building foundation in order to minimize possible clogging of the
building sewer.
5 Unless otherwise approved by the LEA, crossing of water lines and effluent sewer lines is prohibited.
6 A system may be installed underneath overhead power lines or cross other utilities (e.g., canals) providing all of
the following conditions are met:
a. Written authorization is received from the utility company operating and maintaining the utility
affected or for which the easement or restriction was granted;
b. The LEA determines that the encroachment is necessary and there is no other viable area in
which to install the system; and
c. All construction modifications required by the LEA and the affected utility company(ies) are
instituted to carry out the purposes of this Manual.
[NEW CHAPTER]
Chapter 18. Requirements for the Repair/Replacement of Failing Systems
When on-site wastewater system repairs are made, the system must be brought into
compliance with the provisions specified in the new On-Site Wastewater Systems Ordinance
and On-Site Wastewater Manual "...to the maximum extent feasible."
The following guidance outlines how this requirement is to be interpreted; however the EH
Director may consider exceptions based on unique circumstances.
A. Any on-site wastewater system that has been permitted by this office will not be
required to upgrade to current standards as long as the system does not fail, resulting in
backup of sewage into the structure being served or surfacing sewage.
B. Septic Tank
1. Upgrade to current tank capacity standards1 will be required when either:
a. The existing tank is significantly undersized, substandard in construction,
or located with inadequate setbacks to prevent maintenance; or
b. The existing tank is found to be leaking.
2. Existing septic tanks will be considered significantly undersized and must be
brought up to current standards when the tank volume is less than the minimum
volume shown in the following table:
Number of Bedrooms Minimum Tank
Volume(gallons)
1 750
2-4 1,000
5 1,250
6 1,500
3. Mobile Home Park Community Systems: When determining whether a septic
tank needs to be upgraded, based on volume considerations, the following
design factors need to be considered by staff:
a. Actual and potential daily wastewater volume:
• Design flow (250 gpd/mobile home)
• Number of bedrooms
• Occupancy
b. Generally, two mobile home units are the most that can be allowed to be
served by a single 1,000 gallon septic tank.
1 Current standards require a 1,500 gallon septic tank for up to a 4-bedroom residence and an
additional 200 gallons for each bedroom thereafter.
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4. Wooden, leaking, or deteriorating tanks will need to be replaced due to concerns
about structural integrity, substandard construction, and potential leakage. Note:
Wooden tanks identified through routine septic pumping will be considered
substandard and require replacing with an approved tank as specified in the On-
Site Wastewater Manual.
5. The LEA will not authorize installation of a wooden cover on a septic tank due to
the inability of the replacement lid to be watertight and have the needed
structural integrity to be safe. On a case-by-case basis, the LEA may consider
approval of an engineered concrete top replacement for a concrete septic tank,
provided the tank is not located in an area with high seasonal groundwater.
6. Leaking clamshell septic tanks may be sealed rather than replaced, provided:
a. The work is performed by a Certified Installer;
b. The Certified Installer notifies the LEA as provided in the On-Site
Wastewater Ordinance;
c. The Certified Installer completes and submits to the LEA an As-Built on
the form provided by the LEA that verifies that the 24-hour leak test was
performed and the tank did not leak; and
7. Septic tank leak testing will be required for all septic system repairs, except this
requirement may be waived by the LEA for existing septic tanks serving occupied
dwellings when the following conditions are met:
a. The tank is pumped and observed to be in good structural condition; and
b. The tank is not located in an area with high watertable.
C. Test Hole Analysis
Soil test holes will be required for determining dispersal field size and depth except
when soil records in the files are sufficiently detailed and complete for determining
optimal dispersal field size and depth. In order to meet this requirement, soil log data
must be from a location in proximity to the proposed dispersal field and recorded in
sufficient detail to determine application rate and depth to a restrictive layer, if present.
D. Guidance for Requiring a Certified Designer
1. Some parcels requiring wastewater system repair have one or more site
constraints making design of the replacement system challenging and more
complex. Site constraints could be due to parcel size, location of existing
structures, landscaping features, and site characteristics requiring setbacks.
2. When the LEA believes site constraints are of such a serious nature as to require
the use of a Certified Designer, the property owner will select a Certified
Designer to assist with evaluating the site and designing the replacement
wastewater system.
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3. Unless an exemption is granted by the Environmental Health Director or Land
Use Manager, the LEA will REQUIRE use of a Certified Designer when BOTH of
the following site constraints apply:
a. Insufficient useable drainfield area is available for dispersal field sized on
the basis of trench bottom area only; and
b. No additional area is available for future repair after placement of current
repair.
4. When parcels have only ONE of the two site constraints listed above, but also
have one or both of the following additional site constraints: (i.) Less than 12
inches of vertical separation (distance between dispersal field bottom and
restrictive layer or seasonal water table) for dispersal field; or (ii.) Receiving soil
identified as a Class A, E, (or undesignated), the LEA will meet with the property
owner and the Certified Installer to:
a. Explain to the homeowner the risk and potential cost of future repairs;
and
b. RECOMMEND that the homeowner utilize the services of a Certified
Designer to design the repair system.
E. Insufficient Useable Drainfield Area
When there is insufficient useable area on a parcel to repair a system using bottom area
only for drainfield sizing, the LEA may consider one of the following alternatives:
1. Determining required bottom area using percolation testing;
2. Increasing trench width;
3. Use of a bed instead of trenches;
4. Use of pressurized distribution fora 25% sizing reduction;
5. Use of supplemental treatment and pressurized distribution fora 50% sizing
reduction; or
6. Use of sidewall area using the calculations specified in the Manual of Septic Tank
Practice.
F. The LEA may require additional design features when there is evidence that a
wastewater system sized on the basis of the number of bedrooms alone would be
undersized and subject to premature failure. The following table shows the maximum
occupancy for a residence when the design flow is based solely on the number of
bedrooms:
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Number of Bedrooms
Maximum
Occupancy
Design Flow
(based on 60 gpd/occupant)
2 4 240
3 6 360
4 7 420
5 8 480
G. Use of a Bed in Lieu of Trenches
1. Definition of a "Bed System": A dispersal system is designated a "bed" system or
a "seepage bed" when the excavation width exceeds 36 inches. Bed systems may
be a viable option for system design when site constraints do not allow
placement of a conventional trench system meeting current sizing requirements.
2. Special distribution considerations: To assure that the entire bottom area of the
bed will be utilized for dispersal, that treatment by the receiving soil will be
maximized, and that localized groundwater mounding will be minimized, bed
systems may be required by the LEA to utilize pressurized distribution.
3. Special sizing considerations for bed systems wider than 4 ft: Dispersal systems
are sized based on the anticipated quantity of wastewater (design flow) and the
capacity of the receiving soil to disperse the wastewater (application rate). Only
the bottom area of the dispersal field is used for its sizing. From time to time,
however, the design flow may be exceeded for short periods of time. Under such
conditions of peak loading, trench sidewall dispersal provides an additional
safety factor for conventional trench systems. Because bed systems have limited
sidewall area in relationship to bottom area, bed systems wider than 4 ft need to
be increased in size by 50%. If pressurized distribution is utilized the size will only
need to be increased by 25% (based on a 50% increase per the UCP, minus the
25% credit for the use of pressurized distribution).
4. Special construction considerations:
a. Beds should be constructed only when the soil is sufficiently dry so that it
will not seal or compact during installation
b. No excavation equipment, including tracked vehicles, should be used
inside of the bed
H. Equal Distribution
1. Equal distribution by appropriate placement of "T"s and distribution boxes will
be required within the dispersal field;
2. When site conditions do not allow equal distribution using gravity dispersal,
pressurized distribution will be required.
Pump and Pressure Distribution
Gravity systems will be required to utilize pumps and pressurized distribution as follows:
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1. Utilization of an Effluent Pump: An effluent pump is required when the depth of
the plumbing without its use would result in either:
a. Effluent discharged less than 12 inches above a restrictive layer such as
hardpan or a seasonal watertable (as evidenced by mottling or presence
of groundwater) and use of the pump would significantly increase the
vertical separation, or
b. The bottom of the dispersal field being deeper than 5 ft below finished
grade.
2. Utilization of Pressurized Distribution: Whenever a pump is required for a
system repair, as specified in Subsection a, above:
a. Staff will explain the benefits of using pressurized distribution;
b. Pressure distribution will only be required when a pump is needed as
specified in Subsection 1.a. of this section, and when equal distribution
utilizing gravity dispersal is not feasible due to site constraints.
Supplemental Treatment
Wastewater systems will be required to utilize supplemental treatment when one of the
following conditions has occurred and an alternate remedy is unavailable:
1. The site is located in a designated Area of Environmental Concern and
supplemental treatment is specified as a mitigation; or
2. Effluent dispersal is into a soil that is seasonally inundated by groundwater (i.e., 0
vertical separation); or
3. Available area for the dispersal field is significantly undersized based on the daily
design flow and application rate of the receiving soil; or
4. The dispersal field will be excavated closer than 50 ft to a down gradient
(unlined) surface water or closer than 25 ft to an up-gradient (unlined) surface
water; or
5. Wastewater strength is significantly greater than domestic strength.
K. Requirements Pertaining to Minor Repairs Requiring LEA Notification and Plan Review
under Section 19-7 D.2. of On-Site Wastewater Ordinance:
1. In general, a minor wastewater system modification or repair that does not
require completion of a Site Assessment or soil evaluation, or involves
replacement of no more than 10 ft of drainpipe due to crushing or root intrusion
does not require a full Construction Permit.
2. No on-site wastewater system components can be serviced or repaired without
notifying the LEA for plan review.
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3. Other than replacement of septic tank inlet and outlet T's or replacement of
septic tank lids, LEA Notification and Plan Review must take place BEFORE the
service is performed.
4. LEA staff will make plan review a high priority activity, typically performed by a
simple telephone call to the LEA and conversation with an inspector. Photographs
sent via email may, at the LEA's discretion, be accepted in lieu of an actual site
inspection.
5. When a site inspection is not waived by the LEA, an inspection by the LEA will be
performed whenever possible while the installer is on site performing the
component replacement or modification and no later than one working day from
the date of notification and plan review or else the installer is authorized to
complete the work and cover the system.
L. Whenever, in the determination of the LEA, insufficient area will remain for system
replacement in the event of failure of the current repair being permitted, the APN file
will be clearly flagged with this information and Trakit will be flagged so that the
information will be readily accessible by future property owners.
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