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7 F commercial properties to the west, toward the City of Tracy, and medium density the southwest, all of which are on septic systems. The Parcel Viewer Map illustrates he subject property is situated downgradient from this entire approximate one-square mposed of this commercial/residential section. Applications on file with the County Environmental Health Department reveal that there have been five permits issued for repairs/additions to existing systems on Chrisman Road, north of I I" Street, including for th subject site itself. This can be regarded as a high number of repairs/additions, and can be attributed to: 1.) The clay soil structure existing at typical leachline depths, and 2.) Inadequate disposal area due to parcel area constraints. B. SOIL PHYSICAL CHARACTERISTICS AND ANALYTICAL TEST RESULTS The project site has level terrain; consequently,there will be no need to incorporate design considerations for slopes within the filter bed area. The United States Department of Agriculture - Soil Conservation Service(USDA-SCS) indicates the on-site soils to consist of a Capay Clay- Urban Land Complex (122). This soil unit contains 50% Capay clay which correlates with the clay soil texture test results of the future filter bed soil of 53%. Three, 10-foot deep hand borings were completed for this study. The first boring was drilled in the northeast corner of the proposed new filter bed, near the entrance to the facility. The second boring was drilled also in the northeast corner of the existing leachfield area. These three borings provided: 1.) A profile of the underlying soil characteristics, 2.) Depth to groundwater and 3.) A water table sample for analysis. The log of boring illustrates the subsurface soil characteristics encountered in the proposed future filter bed area: The surface soils to 1.0 ft consist of aggregate base (AB)material that is highly compacted, yet somewhat permeable. Below this base and extending to 3.5 ft is a dark brown, fractured clay with consistent moisture. From 4 ft to boring termination at 10 ft, the soil consists of a yellowish brown silty clay with a higher moisture content. At 7.5-8.0 ft is the capillary fringe with the zone of saturation at 9.0 feet. The static water level was 9.0 ft. No rust mottling was observed which would be indicative of seasonal soil saturation. Two soil samples were obtained from the proposed future filter bed area for chemical analyses, from depths of 36 inches (Sample Number FFB36) and seven feet (Sample Number FB7FT) . As the noted on the SOIL ANALYSIS REPORT, the nitrate-nitrogen (NO3-N) concentration at the 36- inch depth elevation is 66 ppm, which is very high, but drops to a medium concentration of 13 ppm at 7 ft. This concentration difference may be attributed to denitrification occurring within the indigenous clay soils profile. The 66 ppm NO -N is inexplicable_ but could be attributed to historical agricultural practices. Additional chemistry of the soil sample was also done to analyze several constituents related to nitrate loading. The important parameters for nitrate loading assessment are the organic matter, pH, cation exchange capacity(CEC), clay content percentage, along with nitrate-nitrogen content. Chesney Consulting