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Design parameters for the proposed mound system can be found in Appendix G. Design of the mound system for the Temple is based upon operating parameters, specifically wastewater flows, longevity, and environmental protection. If plumbing fixtures do not presently consist of low volume units as specified in the Uniform Plumbing Code(UPC), new low volume fixtures must be installed. These fixtures (toilets, sinks, etc.)must be checked regularly for leaks which would cause excessive water flow to the septic tanks. SEPTIC TANKS There are presently three - 2,000 gallon septic tanks in series being used for wastewater treatment from the Temple. Based upon the anticipated sewage flow this, current septic tank capacity should be adequate. The following calculation indicates there is sufficient detention time: Detention Time= 6,000 gal tank capacity x 0.70 (30%volume lost to sludge/scum accumu_lation� 3 (Peaking factor) x 2,500 gallon/day Detention Time= 0.56 days. The minimum acceptable detention time should be approximately 0.5 day. This calculation excludes low use of the system Monday through Saturday. IMPACT MITIGATION Nitrate-nitrogen impact from the proposed mound system will theoretically be mitigated by the following design: First, by using three - 2,000 gallon septic tanks in series, there will be a higher percentage of solid organic material trapped within the tanks. Additionally, a filter should be installed on the last tank (e.g., Zabel® or OSI®Filters) before the effluent is pumped to the mound. Secondly, there is evidence that septic tanks have the capability to denitrify nitrate by the following process: As influent enters the first tank, the wastewater has been aerated from flushing action, the aerator on faucets, etc. But as the oxygen is consumed by microbiological processes,the tank becomes anaerobic and the microbes begin to use nitrate as an electron acceptor. When the effluent reaches the second tank and particularly the third tank,there is theoretically little oxygen within the tank contents,thus promoting denitrification. This is the reason 50%nitrogen removal was assigned in the calculations above. Thirdly, as the effluent travels through the "fill" portion of the mound system, environmental conditions (primarily aerobic conditions) may promote nitrification. However, when the effluent enters the native clay soil where the microsites within the clay lattice structure are anaerobic, denitrification should be promoted. A figure of 25%nitrogen removal by denitrification has been estimated in the above calculations. 6 Valley Ag PSjearch