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[5] LOCAL GROUNDWATER AND SURFACE WATER INFORMATION The groundwater, or the zone of saturation is located approximately 75 ft below grade according to information from the Flood Control District. There was no evidence of a perched water table condition during our exploratory boring procedures. Analysis of water drawn from a well at the west end of the entrance road to the ranch, illustrates a concentration of nitrate at 46 ppm NO3. This is 1 ppm over the Maximum Contaminant Level (MCL) of 45 ppm. Although it is unknown if this well is used for domestic purposes, water from it should not be consumed by infants. This increased level of nitrate is probably due to the farming intensity in the region. Per the requirements of the Environmental Health Department, DBCP was also analyzed and found to be non-detect(ND) in the well water. There are three surface water conveyance structures in the locale of the project: The Banta Carbona Irrigation District Middle and Main Canal, and the Mendota Canal. There is no potential impact from the proposed septic system to these surface waters. [6] CONCLUSIONS The percolation test results indicate a septic system with a 8,000 to 10,000 square foot leachfield may be utilized. The proposed structure on Parcel'I must have seepage pits installed at the ends of the leachlines. The final length of leachline and the final number of seepage pits will be dependant upon the number of bedrooms the residence will have. If there will be three or more children within the household, additional pits should be considered. A 50% standby replacement area must also be incorporated into the leachfield area. It is our recommendation that a perc test should be conducted in the exact location of a proposed septic system on any of the other parcels to test for adequate effluent acceptance. The Permit Applications for repair/additions indicate seepage pits are warranted. The referenced septic design for leachfield and pits will help ensure stability and guard against leachfield and pit failure. A failure would primarily result from the formation of a "biomat" or "clogging mat" on the wetted soil where the effluent enters the soil. This mat is composed mostly of aerobic and anaerobic bacteria and bacterial products consisting of a slime of polyuronides and Vafley Ag Psearck