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D. OPERATIONAL PARAMETERS AND COMPONENTS SSS§ 3.7. An overview of the system operation to serve the proposed residential structure is as follows: Influent will gravity flow into a P&L Concrete, Inc. standard precast, 1,200 gallon septic tank. The tank must be set perfectly level and as high in elevation as possible. A Polylok® PL-68 effluent filter is to be installed on the sanitary tees of both side outlets of this tank. Clarified effluent will gravity flow equally from both side outlets to 3" perforated pipe running down the centers of both 7 ft wide, 37 ft long filter beds. Perforated pipe is to run level, with capped ends to force as equal effluent distribution as possible. A minimum of 12" of washed drain rock, and preferably 18" of rock, is to be placed under the perforated pipe, and extending 2" above the perforated pipe. Geotechnical filter fabric is to be placed over the drain rock and backfilled to final grade with native soil. Due to the nitrate loading calculations demonstrating a loading theoretically exceeding the Maximum Contaminate Level, nitrate loading mitigation measures are discussed in the Conclusion Section below V. CONCLUSIONS AND RECOMMENDATIONS NLS§ 4.2. The shallow subsurface soils underlying the subject property where the two new filter bed disposal areas are to be installed, reveal a sandy loam soil structure with comparatively rapid permeability and a high degree of natural denitrification potential. This potential is based upon the observed significant decrease in nitrate-nitrogen concentration with increasing soil depth. NLS§ 4.1. As referenced, the nitrate loading calculations show the resultant effluent from the proposed primary residential structure will theoretically possess a concentration of approximately 32 ppm as nitrate-nitrogen, which exceeds the MCL for nitrate-nitrogen at 10 ppm. Consequently, nitrate impact mitigation measures must be implemented. The importation of organic material onto the floor of the filter bed must be done to prevent the nitrification process at the soil-effluent interface. A sample of sawdust (referenced as "White Wood Fines") was obtained from Recology Blossom Valley Organics, located at 6133 Hammett Ct., Modesto, CA and submitted for laboratory analysis with the following results: TABLE 2 ANALYTE 1 RESULTS Nitrate Nitrogen <0.003% Ammonia Nitrogen 0.010% Organic Nitrogen 0.27% E.C. 1 7 mmhos/cm pH 6.6 C:N Ratio 165:1 Page -7- f Chesney Consulting