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V V §5.4. A Well Driller's Log exists for the Silva's on-site domestic well. Underground lithology specific to the subject property consists of hardpan, sandy clay, clay coarse sand and gravel. Clay strata down to 38 feet may have an attenuating effect on nitrate formation. §4.2. and §4.4. The two well water constituents typically sampled for EHD requirements are nitrate and the agrichemical DBCP (Dibromochloropropane) and EDB (Ethylene Dibromide). Since the region has been in agricultural production for several decades, nitrate impact was to be expected. DBCP was not expected in this area due to lack of vineyard production, and was not detected in the analysis. §4.3 and §4.5. A water sample was obtained from a hose bibb next to the garage/shed at Mr. Inman's residence (16426 Steinegul Road), and a sample from a hose bibb at the pressure tank of the Silva's domestic well (28851 Kelly Road). Both samples were taken after the wells cycled three times to ensure the sampling of aquifer formation water. VOA amber glass sample bottles were used for DBCP/EDB analysis and one-half lite plastic bottles were used for nitrate analysis. §4.6. The samples were placed in a cooled ice chest and transported under the attached Chain of Custody to A &L Labs in Modesto, California, found in Appendix B. I Water anal veals medium-to-high nitrate concentrations,- ,_21 ppm nitra for Mr. Inman's well anm nitrate_ r the Silva's well. The Maximum Contamman 3 dPrlg;Tg-�-w-at-e-r-i-s-4-5--p-p--m-.-"These nitrate concentrations can be attributed to the comparatively deep groundwater, high clay content intervening strata, and very low septic system density. Otherwise, under different conditions, such as a high water table, the nitrate concentration may be much higher. §7.0 CONCLUSIONS The perc test results for proposed Parcels 1 and 2 show acceptable percolation for the management of septic system effluent flows at the deeper depths representative of sumps. As noted for the shallow tests on Parcels 1 and 2, there will be some effluent percolation at leachline depth, but if the soil becomes saturated, percolation will cease and the sumps will manage effluent flows. The deep perc tests were run at simulated sump depths due to the encountered material which was the most favorable material at the highest elevations. Consequently, sumps and possibly limited depth seepage pits may be installed on these two Parcels in the location of percolation testing. A new law that is to be enacted may restrict the installation of seepage pits (Assembly Bill 885). Before this law is implemented, EHD may require the installation of seepage pits on Parcels 1 and 2 for a number of reasons: 1.) They are the typical and principle effluent management structure installed in this area, 2.) There is a distance of approximately 45 feet between the bottom of a seepage pit at 25 feet b.g.s. and the current groundwater depth of 70 feet, 3.) Seepage pits allow head pressure buildup to force effluent into the underlying anaerobic clay soils, 4.) If effluent levels rise 10 feet above the bottom of the seepage pit, the effluent could then be managed by the more permeable silty sand strata encountered at the tested depths. Page-4- Chesney Consulting