These criteria prescribe conditions for waste disposal from septic tank-leaching systems for single family residential units or the equivalent and do not preclude the establishment of more stringent criteria by local agencies or the Board. The Board may prohibit the discharge from septic tank-leaching systems which do not conform to these criteria. Systems which cannot meet the following criteria may be allowed in selected areas if they are individually designed. The criteria may not be applicable in all cases to commercial or industrial developments. An adequate replacement area equivalent to at least the initial disposal area shall be required at the time of design of the initial installation and incompatible uses of the replacement area shall be prohibited.
Distance is measured from the top edge of the bank.
Minimum Criteria 1. The percolation rate shall not be faster than 5 minutes per inch unless it can be shown that a sufficient distance of soil is available to assure proper filtration. Soil depth below the bottom of the leaching trench shall not be less than 5 feet nor less than 10 feet below the bottom of a seepage pit. Depth to anticipated highest level of groundwater below the bottom of the leaching trench shall not be less than 5 feet nor less than 10 feet below the bottom of a seepage pit. Greater depths are required if soils do not provide adequate filtration.