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L � (§ 4.0) LOCAL GROUNDWATER AND SURFACE WATER INFORMATION (§4.1) The 1999 Lines of Equal Depth Map published by the San Joaquin County Flood Control illustrates the groundwater depth to be 105 feet below ground surface (b.g.s.). The 1999 Lines of /1 Equal Elevation Map illustrates the groundwater elevation to be relatively flat, with a flow in a J southwesterly direction. Deep, underground lithology specific to the subject property cannot be discerned since there were no well logs at EHD for any of the on-site wells. However, a Well Drillers' Logs was found for a J` nearby domestic well. The attached well log indicates the surrounding morphology shows intervening strata of clay, sand and gravel. It will be the determination of the surveyor of the project to determine if the property is subject to 100-year flooding. Surface water is managed by the surrounding farmland. (§ 4.3 and 4.5) A domestic well that serves the residence, located at the southwest corner of the /�3, barn,was sampled from the hose bibb next to the northwest corner of the hose. The well ran for `( 15 minutes to ensure the sampling of aquifer formation water before sampling. (§4.6) A plastic bottle was used for the nitrate sample and two amber VOC bottles with preservative were used for the Dibromochloropropane (DBCP), and Ethylene Dibromide (EDB) samples. The samples were placed in a cooled ice chest and transported under the attached Chain of Custody to A &L Labs in Modesto, California to be analyzed. 7 (§4.2 and 4.4) Water analysis reveals a low nitrate(as nitrate -N00 concentration of 13 ppm for the domestic well. DBCP and EDB were found to be Below Detectible Limits(BDL). The /y N Maximum Contaminant Level (MCL) for nitrate in drinking water is 45 ppm. This 13 ppm nitrate l J concentrations may be considered a background concentration that has accumulated over eons. Since 1.) The groundwater is deep, 2.) There are high clay content intervening soil strata, 3.) Low septic system density surrounds the property, nitrate impact may be attenuated over time. (§ 7.0) CONCLUSIONS The pere test results for the proposed three Parcels show acceptable percolation for the management of septic system effluent flows. Out of the six perc tests, only the shallow test on Parcel l had unacceptable perc rates. This maybe due to soil compaction in this area from farm equipment. Although the deep perc tests were run at depths shallower than 25 feet, it will be the requirement of (& EHD EHD to install 25 feet deep seepage pits for this property if an application to build is submitted. The underlying soils possess increasing moisture content with increasing depth. This may be due to last winters' heavy rainfall during 2004/2005. High moisture content clay soils are beneficial for the suppression of nitrification, and the promotion of denitrification of nitrate molecules that may r� have formed through nitrification in the upper, more favorable soil environments. This also may have contributed to the low nitrate concentration observed in the well water, along with attenuation of nitrification. Page -4- Chesney Consulting