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Fami.alytical al Test Results assessment of the subsurface soils was done on the samples retrieved from the deep he test results noted on the Soil Analysis Report in Appendix 3. This chemistry was done eral constituents that influence nitrate loading: specifically adsorption,nitrification and . The important soil parameters for nitrate assessment are the organic matter,pH,cation exchange capacity(CEC), and indigenous nitrate-nitrogen content. As noted from the test results,the organic matter within the soil profile is low. The nitrate-nitrogen content show a consistent nitrogen concentration throughout the soil profile that does not exceed 10 ppm as NO3-N. Although equating soil nitrate-nitrogen content with vadose zone water content is difficult, the concentration of 10 ppm NO3-N can be considered low,particularly in soils under past agricultural practices. Since septic tank effluent is composed predominately of ammonium(NH4),the pH, along with the CEC, have influence on ammonium molecules. The pH of the soil profile is alkaline with all samples above 8.0. This pH profile may have a defined suppression effect on nitrate stability after formation by increasing the potential for denitrification. The CEC measures the ability of the soil to theoretically trap and hold ammonium molecules. Cation Exchange Capacity test results for all of the soil sample depths, except the 20-ft depth, shows that CEC may also have an influence on suppression of nitrification. 3. GROUNDWATER / SURFACE WANER INFORMATION Ultimately, deep percolation of wastewat effluent, stormwer and domestic irrigation water recharge the underlying groundwater. This recharge volume difficult to determine due to several factors such as evapotranspiration (evaporaiaia "-anspifation), horizontal conductivity, and precipitation/domestic irrigation infiltration volumes. Stormwater from the project will be managed on-site by a shallow ballfield and subsurface drains. There will be drains downgradient from the wastewater disposal area,while the stormwater recharge from the ballfield will be cross- gradient. The subsurface fresh water recharge will have an unquantifiable dilution effect on the percolating wastewater effluent. Aquifer Information: Groundwater Historical Depths and Direction of Flow The attached well logs from domestic wells in proximity to the project illustrate potential water bearing strat istorical depth to the static water table. The closest domestic well, found at Corr w Ro , north of Valpico Road(26909 Corral Hollow) shows a water bearing strata fro 8 to 102 ft with the static water table depth to be at 30 ft in October 1973. Another nearby do m ell (11 45 West Valpico) suggests a water bearing strata from 163 to 183 ft,with a depth to fi ter at 58 feet below ground surface and a static water level depth of 54 feet in January 2001. This static water table depth is similar to that encountered in our deep boring. Additional well logs are attached, showing a significant depth to groundwater further south on Corral Hollow,primarily due to the increase in land surface elevation. The groundwater directional flow usually follows the topography of the land. It is generally accepted the groundwater flow in the Tracy area is toward the San Joaquin River. Since the declination of the subject property topography is due north, groundwater directional flow is between north and northeast. Page -8- Chesney Consulting