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LOGE 1847: Jhamat SS/NLS Addendum 2 Page 3 <br /> March 18, 2019 <br /> radius surrounding the Site, five wells have been tested for nitrate. Nitrate was <br /> not detected above the MCL in any of the wells, and was detected below 5 mg/L- <br /> N in four of the wells (Plate 4). The Morada area is almost completely developed <br /> with residential parcels similar in size to the subject Site, and it does not appear <br /> that water quality has been degraded substantially. <br /> • Additionally, depth to ground water beneath the Site is estimated to be 88 to 95 <br /> feet, as discussed in the original report. San Joaquin County experienced its <br /> highest recent ground-water levels in 1983 and 1999. Review of ground-water <br /> maps for these years (Plates 5 and 6) reveals that depth to water would have <br /> been approximately 65 feet during these high periods. Even assuming the most <br /> conservative (shallowest) ground-water depth, the vadose zone of the new septic <br /> system will be relatively deep, extending from the bottom of the 25-foot seepage <br /> pits to 65 feet below ground surface. Significant nitrate attenuation would be <br /> anticipated over the course of this 40-foot span. <br /> • As discussed above, the area is underlain by approximately 30 feet of clay strata <br /> within the vadose zone. Clay is known to inhibit the downward percolation of <br /> water and may mitigate nitrate as well through adhesion to the soil particles. <br /> It is our professional opinion that, based on the factors discussed above, septic effluent <br /> from the subject Site is unlikely to raise nitrate levels in the ground-water to above the <br /> MCL. Use of a standard septic system with leach lines and seepage pits should be <br /> permitted. <br /> Sincerely, <br /> Live Oak GeoEnvironmental, Inc. <br /> SS%pNAL �Fo �c,`ptrAt GF0 <br /> pkv' �O �� �i.•. � <br /> Abigail Racco, REPA Q <br /> Q DAVID J.WELCH <br /> * N0.2151 <br /> CERTIFIED * ♦[ C� <br /> �S, ; <br /> AJENGINEERING <br /> ��OGEDlOG15TF �R�P � �. <br /> David J. Welch, CEG, CHG, PGP CAUL OF C�,\� <br /> CC: Manjinder Jhamat <br /> 5310 Las Positas Cir. <br /> Stockton, CA 95212 <br /> Attachments: <br /> Plate 1. Recharge Calculation (Evapotranspiration Method), Holt Station <br /> Plate 2. Recharge Calculation (Evapotranspiration Method), Staten Island Station <br /> Plate 3. Nitrate Loading Calculation (Evapotranspiration Method) <br /> Plate 4. Nitrate Detections in Nearby Wells <br /> Plate 5. Depth to Water, 1983 <br /> Plate 6. Depth to Water, 1999 <br />