(a) An applicant initiating a land use project that cannot be served by a public sewer system shall complete a site evaluation to determine suitability to meet system requirements for onsite wastewater dispersal as described in this chapter and the Manual.
(b) Unless waived by the Director of Environmental Health, no lot shall be created, no parcel or subdivision map shall be recorded, nor shall a lot line adjustment be approved unless all proposed lots or parcels which rely, or will rely on a system, as defined in this chapter, have an approved site evaluation report that verifies the existing and/or proposed lots or parcels have the required minimum usable wastewater dispersal area (MUWDA) in accordance with the horizontal setback requirements shown on Table 1 for each existing or proposed residence. Non-residential land use project(s) shall submit a site evaluation report and proposed system design.
Table 1: MUWDA Requirements per Residence
USDA Soil Texture Classification | Percolation Rate (minutes/inch) | MUWDA (square feet) | |
Gravity Distribution | Pressure Distribution | ||
USDA Soil Texture Classification | Percolation Rate (minutes/inch) | MUWDA (square feet) | |
Gravity Distribution | Pressure Distribution | ||
Coarse sand | <1 | Not Suitable for Lot Creation
| |
Coarse to medium sand
1,2 | 1-5 | Not Allowed | 6,000 |
Fine sand and loamy sand 3 | >5-10 | 9,000 | 6,000 |
Sandy loam, loam, sandy clay loam | >10-24 | 12,000 | 8,000 |
Silt loam | >24-60 | 15,000 | 10,000 |
Clay loam, silty clay loam, sandy clay 4 | >60-120 | Not Allowed | 15,000 |
Clay 4, highly compacted soil | >120 | Not Suitable for Lot Creation | |
Imported soil | Not applicable | Not Suitable for Lot Creation | |
1 Subject to percolation test in addition to using soil texture determination.
2 Must demonstrate adequate filtration capacity
3 Subject to percolation test in addition to soil textural determination if 35% or more (by volume) coarse fragments (defined as > 2 mm size)
4 Clay shall be non-expansive
(c) No lot shall be created, no parcel or subdivision map shall be recorded, nor shall a lot line adjustment be approved where a non-discharging wastewater disposal unit is the proposed method of wastewater disposal in lieu of an onsite wastewater treatment system.
(d) No reduction in MUWDA size shall be granted for proposed supplemental systems.
(e) Except for community systems, no new lot or parcels shall be created where the lot or parcel relies on a system that cannot be sited within the boundaries of the proposed lot or parcel.
(f) The Director of Environmental Health may approve specifications for MUWDAs for non-residential projects, cluster systems, and community systems that vary from Table 3 on a case-by-case basis under the requirements of this ordinance and Manual.
(g) The minimum size of a newly created individual lot within the unincorporated area of the County that is served by a system shall be two (2) acres. The minimum size of a newly created individual lot within the jurisdiction of the City of West Sacramento shall be one (1) acre. Minimum lot sizes within geographic areas will be re-evaluated periodically based on results of the Water Quality Assessment Program.
(h) Within the unincorporated areas of Yolo County, no system shall be constructed within a residential subdivision of five (5) or more lots, or parcels in which any one (1) parcel is less than five (5) acres net size, for which a tentative subdivision map is approved after October 7, 1976.
(i) The maximum slope for the designated MUWDA on newly created lots served by a system shall be no greater than thirty percent (30%).
(j) No new lot or parcel shall be created where the vertical separation is less than two (2) feet.
(k) Proposed new lots or parcels shall specify the MUWDA on all maps. The MUWDA shall be outside of the following:
(1) Minimum horizontal setbacks as specified in Table 1.
(2) Easements dedicated to surface or underground improvements.
(3) Easements for access for roadway purposes.
(4) Paved areas
(5) Areas with a slope in excess of thirty (30) percent.
(6) Areas subject to flooding as determined in the site evaluation
(7) Areas within required setbacks to a flood control levee.
(Ord. 1469, eff. July 14, 2016)