Tuolumne County Municipal Code Ch. 13.04 Onsite Wastewater Treatment Systems

Sections:

• 13.04.010

• Definitions.

• 13.04.020

• Purpose - Construction.

• 13.04.030

• Compliance - Exceptions.

• 13.04.040

• Authority to enforce Uniform Codes.

• 13.04.050

• Enforcement authority.

• 13.04.060

• Horizontal distances.

• 13.04.070

• Minimum criteria.

• 13.04.080

• Procedures.

Chapter, the following words or phrases have the following meanings:

A. “Disposal area” is the potential disposal area available for the installation of an onsite wastewater treatment system within any lot or parcel, excluding therefrom all unsuitable areas.
Unsuitable areas include all areas within required zoning setbacks, areas within dedicated easements unless the easements are dedicated for liquid waste disposal purposes, areas not owned or controlled by the property owner, areas occupied or to be occupied by structures and paved areas.

B. “Ground slope” shall be measured in percent of grade and is classified in the following categories:

Category

Slope Percent I

Less than 10 percent II

11-20 III

21-30 IV

Greater than 30

C. “Horizontal distance” is the distance in lineal feet measured in a horizontal plane from the nearest edge of any structure, opening or excavation.

D. “Impaired water body” means a surface water body or segment thereof that is identified on a list approved by the State Water Resources Control Board and the US EPA pursuant to Section 303(d) of the federal Clean Water Act.

E. “Net area” of a lot or parcel means the area of such lot or parcel measured in acres less any road rights-of-way, whether dedicated or not.

F. “Onsite wastewater treatment system(s)” (OWTS) means individual disposal systems, community collection and disposal systems, and alternative collection and disposal systems that use subsurface disposal. OWTS do not include “graywater” systems pursuant to Health and Safety Code section 17922.12.

G. “Percolation rate” is the rate determined in accordance with procedures contained in the current United States Department of Health, Education and Welfare “Manual of Septic Tank Practice.”

H. “Public sewer” is a common sewer directly controlled by a public authority.

I. “Shall” is mandatory and “may” or “should” is permissive.

J. “Soil” is a granular or weathered material that can be excavated and handled with a pick and shovel.

K. “Uniform Plumbing Code” is the latest version of such code adopted by Section 15.04.010.

L. Any other word or phrase shall be interpreted and construed in a manner consistent with the Uniform Plumbing Code. (Ord. 3324 § 1, 2018; Ord. 784 § 1 (part), 1974; prior code § 7- 18.1).

Supervisors finds that the uncontrolled installation and maintenance of OWTS have the potential to degrade water quality and to cause health hazards and nuisance conditions, and, therefore, enacts this Chapter to regulate such systems in order to protect the public health and safety. Every effort should be made to connect to a public sewer where reasonably available. This Chapter shall be liberally construed to effectuate its purposes. (Ord. 3324 § 1, 2018; Ord. 784 § 1 (part), 1974; prior code § 7-18.0(a)).

A. Notwithstanding any other provision of this Code except as provided in subdivisions B, C, D, E or F of this Section, no lot or parcel of a gross area of ten acres or less, shall be created or approved on and after January 2, 1975, pursuant to Title 16, unless a tentative subdivision or parcel map including such lot or parcel was approved prior to 13-2

January 2, 1975, without fully complying with this Chapter.

B. This Chapter shall not apply to a lot or parcel that is required to be connected to a public sewer by the Uniform Plumbing Code as adopted by Chapter 15 or unless each such lot or parcel is guaranteed connection to a public sewer, which guarantee shall be in writing from the authority operating the public sewer; if such guarantee is received, resulting in the creation and approval of such lot or parcel, no building permit shall be issued thereafter for any building on such lot or parcel unless such building will be connected to the public sewer.

C. A lot or parcel zoned as an Open Space (O) District may be created and approved without complying with this Chapter. Such a parcel may not be rezoned to any other zoning district unless and until it fully complies with this Chapter. This restriction shall be noted by a certificate on the map. However, failure to place such a certificate on the map shall not affect the enforceability of this restriction.

D. A lot or parcel may be created and approved if an OWTS connected to an approved structure exists on the parcel and the Environmental Health Division of the Community Resources Agency determines that the required subsurface drain field for expansion of the system will exist on the parcel, minimum horizontal distances will be maintained, and that compliance with other provisions of this Chapter are not required to protect the public health or safety. The Environmental Health Division may require an inspection of the existing system and proof of one or more of the minimum criteria pursuant to Section 13.04.070. The applicant may obtain approval of the lot or parcel under subsection A of this Section without reference to this subsection.

E. Existing lots may be combined by merger or reversion to acreage as defined in Title 16, without complying with this Chapter. The reestablishment of the original lot configuration or a proposal to resubdivide shall fully comply with this Chapter.

F. A lot line adjustment or resubdivision shall not be approved without complying with this subsection:

1. Lots developed after March 6, 1974: A lot line adjustment or resubdivision may be approved, as provided for in Title 16, without otherwise complying with this Chapter if an acceptable OWTS connected to a structure exists on the lot or parcel, if the Environmental Health Division determines that existing OWTS will meet setbacks pursuant to Chapter 13.08, or Chapter 13.04 for developed lots created or approved for individual wells after January 2, 1975, and that the minimum required subsurface drainfield expansion area for repair of the existing OWTS will exist on each applicable lot or parcel after the lot line adjustment or resubdivision.

2. Lots developed prior to March 6, 1974: For purposes of this Section, on lots or parcels with OWTS installed before March 6, 1974, minimum required expansion area shall be any existing expansion area up to 100 percent of that required for the original system, unless a reduction of that area is approved by the Environmental Health Division. A reduction may be approved only upon a determination by the Environmental Health Division that doing so does not create a condition that upon failure of the existing system will create a greater potential to degrade water quality, or to cause health hazards or nuisance that existed before the proposed lot line adjustment or resubdivision.

3. Vacant lots created after January 2, 1975: For a lot line adjustment or resubdivision on a lot or parcel created or approved on or after January 2, 1975, unless a tentative map including such lot or parcel was approved prior to January 2, 1975, and where such a lot or parcel is not developed with a structure requiring an OWTS:

a. May be approved without complying with this Chapter if the adjustment or resubdivision will not eliminate any portion of the lot or parcel that was the site of any testing for purposes of originally complying with this Chapter.

b. May not be approved until compliance with this Chapter if the adjustment or resubdivision will eliminate any portion of the lot or parcel that was the site of acceptable testing for purposes of originally complying with this Chapter.

4. Vacant lots created prior to January 2, 1975: A lot line adjustment or resubdivision on a lot or parcel created or approved prior to January 2, 1975, and that is not developed with a structure requiring a septic disposal system, may be approved without complying with this Chapter.

5. An appeal from decisions concerning lot line adjustments or resubdivisions may be made to the Board of Supervisors pursuant to the procedure set forth in Section 13.04.050(B). (Ord. 3324 § 1, 2018; Ord. 3134 §§ 3, 4, 2010; Ord. 2351 § 1, 2000; Ord. 2132 § 9 (part), 1996; Ord. 1863 §§ 1, 2, 1991; Ord. 1803 § 1, 1990; Ord. 1253 § 1, 1983; Ord. 784 § 1 (part), 1974; prior code § 7-18.0(b)).

The enactment of this Chapter is not intended to, and does not, supersede the authority of the Building and Safety Division of the Community 13-3

Resources Agency to enforce the Codes adopted pursuant to Section 15.04.010 on lots or parcels created before or after January 2, 1975. Further, the enactment of this Chapter does not relieve anyone from complying with all other ordinances, statutes, rules and regulations pertaining to the creation or approval of lots or pertaining to the permit requirements of Chapter 13.08 of this Title. (Ord. 3324 § 1, 2018; Ord. 3134 § 5, 2010; Ord. 2314 § 38, 1999; Ord. 1863 § 3, 1991; Ord. 784 § 1 (part), 1974; prior code § 7-18.0(c)).

A. Enforcement authority. The Environmental Health Division of the Community Resources Agency of the County shall enforce this Chapter and is delegated full authority to do so. No parcel shall be approved without the written approval of the Environmental Health Division. The Environmental Health Division shall not approve any parcel unless each complies with this Chapter.
In conjunction with a tentative map application, the owner or his/her agent shall submit to the Environmental Health Division the information necessary to evaluate the disposal area as prescribed by the Director of Environmental Health and include, but not be limited to: soil percolation rates (where required), soil depth to groundwater, ground slope, and horizontal distances. The Director of Environmental Health may require additional information or data which shall be supplied prior to the approval of the parcel. In areas with known groundwater problems, the Environmental Health Division may require additional testing during the crucial months of March through May.

B. Appeals to the Board. In the event that approval of a parcel proposed by a tentative subdivision or parcel map is denied by the Environmental Health Director with the concurrence of the Tuolumne County Health Officer, and the owner or his/her agent have reason to believe that one or more procedural errors had been made, an appeal may be made to the Board of Supervisors whose decision shall be final. The decision to deny the approval of a parcel shall be set forth in writing and shall specify the grounds for the denial. The appeal shall be filed with the clerk of the Board of Supervisors within ten calendar days following the date of the written denial, and shall specifically state the grounds on which the appeal is based. (Ord. 3324 § 1, 2018; Ord. 3134 § 6, 2010; Ord. 2314 §39, 1999; Ord.1560 § 1, 1987; Ord. 784 § 1 (part), 1974; prior code § 7-18.2).

: 13-4

A. The following minimum horizontal distances are necessary to provide protection to water quality and for public health:

HORIZONTAL DISTANCES

WELLS SURFACE DRAINAGE Facility Domestic Public Drainage Course Ephemeral Stream (1) Intermittent Stream (1) Perennial Stream (2) Impaired Water Body
Drinking Water Supply Surface Water Body (3) Lake or Reservoir (above) (4) or Spring Domestic Water Supply Canal, Above Domestic Water Supply Canal, Below (7) Cut or Fill Bank Property Line (6) Septic Tank 50’ 150’ 10’ 25’ 25’ 50’ 600’ 50’ 50’ 100’ 25’ 10’ 25’ Sewer Line 50’ 100’ 10’ 25’ 25’ 50’ 50’ 50’ 50’ 100’ 25’ 10’ 25’ Leaching Field 100’ 150’ 25’ 50’ 75’ 100’ 600’ 200- 400’ 200’ 250’ 25’ 4xH (5) 50’ 13-5

Explanatory Notes:

1. As measured from the apparent edge of channel.

2. As measured from the high water mark which would result from a ten-year frequency flood.

3. Where the effluent dispersal system is within the catchment of a public water system’s surface water intake point, and located such that it may impact water quality at the intake point such as upstream of the intake point for flowing water bodies and the dispersal system is located:

a. Within 1,200 feet from a public water system’s surface water intake point, the dispersal system shall be no less than 400 feet from the high water mark of the reservoir, lake or flowing water body.

b. More than 1,200 feet but less than 2,500 feet from a public water system’s intake point, the dispersal system shall be no less than 200 feet from the high water mark of the reservoir, lake or flowing water body.

4. As measured from the high water line.

5. Distance in feet equals four times the vertical height of the cut or fill bank. Distance is measured from the bottom of the bank.
   Setback is not required if the top of the drain rock is one foot below the bottom of the cut bank. Total distance need not exceed thirty-five feet from top of the bank.

6. When individual wells are used.

7. Below canal means below the bottom of the canal (invert).

B. Encasement in approved pressure pipe or other special protection required if at less distance than shown.

C. Lesser setbacks may be permitted with approved safety provisions. No part of an OWTS shall be located closer than the above minimum horizontal distance for each part of such system. (Ord. 3324 § 1, 2018; Ord. 784 § 1 (part), 1974; prior code § 7-18.3).

A. The following minimum criteria are necessary for the proper functioning of an OWTS on each lot or parcel:

1. The percolation rate in the disposal area should not be greater than sixty minutes per inch.

2. Soil depth should not be less than eight feet. Greater depths shall be required if soils have a percolation rate less than ten minutes per inch.

3. Depth to groundwater shall not be less than eight feet. Greater depths shall be required if soils have a percolation rate less than ten minutes per inch.

4. Ground slope in the disposal area should not be greater than thirty percent.

5. The minimum disposal area should conform to the following:

Minimum Useable Disposal Area Percolation Rate Area in Square Feet

41-60

12,000

21-40

10,000

11-20

8,000

10 or less

6,000

6. Percolation rate tests shall be required in accordance with the following:

Parcel Size

Test Requirements 5-10 acres

If slope in category IV

A. The following procedure has been formulated to recognize the interplay among the minimum criteria set forth in Section 13.04.070. Point allowances are provided for the magnitude of each factor set forth in such criteria. No lot or parcel shall be approved on which a single-family residence could be physically located unless such lot or parcel attains at least thirty-five points by applying the facts relating to each such lot or parcel to the four following graphs:

13-6

SOIL ABSORPTION CAPACITY

13-7

NET USABLE

DISPOSAL AREA vs. SLOPE

13-8

DEPTH TO GROUNDWATER

SOIL DEPTH

13-9

B. Land divisions in areas mapped as “limestone” on the general plan geotechnical maps shall meet the following requirements:

Computation of the points needed for approval of each parcel to be created shall include not less than six points for soil depth and not less than ten points for ground water pursuant to subsection A above. These points may be added to points attained through slope- area and percolation to meet minimum total required per parcel.

Percolation rate shall not be faster than fifteen minutes per inch at a depth of three feet below the ground surface. (Ord. 3324 § 1, 2018; Ord. 1560 § 2, 1987; Ord, 784 § 1 (part). 1974; prior code § 7-18.5) 13-10