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FTheUpercolation COLATION TEST RESULTS tests were conducted on February 24, 2000 under U.S.E.P.A. and San Joaquinironmental Health guidelines. Two perc tests were completed in the proposed primary leachfield area, both displaying comparatively rapid perc test results. One test was done at the anticipated leachline depth of 42 inches and the other test at an anticipated sump depth of 11 ft below grade. As illustrated on the attached FIELD PERCOLATION TESTING REPORT, the perc rate at the shallow depth was approximately 3 times faster than at the deeper depth (10 min/in vs. 33min/in). The perc rates became slower over the test period, indicating the soil was becoming increasingly saturated. D. GROUNDWATER INFORMATION Groundwater elevation are illustrated on maps published by the San Joaquin County Flood Control and Water Conservation District. The Lines of Equal Depth map denote the water table depth at approximately 28 feet below grade. The Line of Equal Elevation indicate the groundwater elevation to be approximately -2 ft below mean sea level. The groundwater under the subject property may be influenced by French Camp Road, the Union Pacific Railroad, Lone Tree Creek and the Stockton Airport. Influence by these structures can be quantified, but is beyond the scope of these studies. As with all groundwater tables, there will be fluctuations in elevation. The critical issue regarding the groundwater elevation under the subject property is that there is sufficient distance between the bottom of the leachline trench (or sumps) and the highest anticipated depth to groundwater for sufficient wastewater treatment to occur. The groundwater directional flow appears to be toward the northeast. As it travels in this direction, the groundwater elevation falls dramatically near the Airport indicating the potential for comparatively rapid groundwater movement. The directional flow of the groundwater should be assumed to be approximate since there are many influences on flow such as the aforementioned structures, and domestic and irrigation wells. To determine the extent of nitrate impact to the underlying drinking water aquifers,two water samples were taken from domestic wells at the east and west properties adjacent to the subject property. There is an irrigation well at the west property border of the subject property, unfortunately it was locked and could not be sampled. A well log was available for this irrigation well and indicates varied soil strata of sand and clay down to the completion depth of 436 ft. When this well was drilled in 1980,the standing water level was 65 ft below grade. The 1992 groundwater Lines of Equal Depth denote the depth to water at 40 ft and it is currently at 28 ft. Therefore,the water table has risen substantially over the last 20 years. Well water from the east well contains a relatively high nitrate concentration at 37 ppm. Water m the west well has a very high nitrate concentration of 52 ppm. The Maximum Contaminant Level (MCL) for nitrate (NO3) in drinking water is 45 ppm. from . 3 va!!ey Ag Research