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(moi, r�Innaccordance with EHD standards, greater than 6 inches of head water was introduced into the test boring, thus illustrating that the soil characteristics are too porous for acceptable permeability. To mitigate this problem, any future seepage pit drilled on this parcel should be drilled to only 18 feet allowing an approximate five foot buffer of clay soil before effluent would enter this porous sandy material. Or, a seepage pit could be drilled to 25 feet and backfilled with a loamy material to the depth of the encountered sandy interval. With regard to the shallow perc test at 42 inches, the test result shows.a perc rate of 62.5 min/in. However, observing the mathematical calculations, it is noted that four hundreds of tenths of a foot (0.04 ft) translate to 0.48 inches when converted. This should be rounded up to 0.05 inches since it is impossible to measure a perc rate in hundreds of an inch. This places the perc rate right at the passing rate of 60 min/in. All of the above information regarding parcel S; the shallow and deep perc tests, mitigation measures and mathematical calculations were verbally discussed with Mike Huggins of EHD on May 24, 2005, with his concurrence. As noted on Table 1, the original perc tests on parcel 4 had failing rates. It was subsequently decided to drill further into the interior of the parcel from MacArthur Road. Care was taken to drill in a safe location since there are natural gas and oil pipelines traversing this parcel. The second tests illustrates marginally passing rates for the shallow boring based upon the mathematical discrepancies discussed above, and an acceptable rate for the sump-depth perc test at 22.7 min/in. Sumps may provide a higher level of protection against nitrate loading. Considering a new law that maybe implemented which may ban seepage pits (Assembly Bill 885), EHD may require sumps be installed for all of the proposed Parcels. It will be at the discretion of EHD to 1.) Install leachlines exclusively on the Parcels with acceptable shallow perc rates, 2.) Install leachlines and sumps, or 3.) Install leachlines and seepage pits based on the criteria explained above. EHD requires that there be sufficient distance for"treatment" of septic effluent before it encounters the groundwater table. This distance is normally regarded to be five feet in leachlines and 10 feet with seepage pits. Therefore, sufficient distance exists between the bottom of a maximum depth seepage pit of 25 feet and the assumed groundwater depth of 78 feet. The number of leachlines, sumps and/or seepage pits, and septic tank sizes are unknown for each of�thearcels at this time since the number of bedrooms for each structure is unknown. V o engineered septic systems are anticipated for this subdivision. Each new system must have a 50% standby replacement area incorporated into the design of the septic system. All related septic system structures and the new domestic wells must comply with the published "distance" requirements from property borders, roads, irrigation fields, irrigation canals, and all pipelines. The observed nitrate concentration of 48 ppm as nitrate may be attributed to the seepage pit/outhouse that served the old residential structure. The indigenous clay surface soil would be expected to offer some mitigation effect against nitrate formation and movement from agricultural inputs. j, Page A 0- Chesney Consulting