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7.Wl <br /> March 8, 2021 <br /> FOR: San Joaquin County Environmental Health Department(EHD) <br /> Mr. Steven Shih, REHS, Unit lI Program Manager <br /> 1868 Hazelton Ave. <br /> Stockton,CA 95205 RECEIVED <br /> PROJECT: 21644 South Corral Hollow Road <br /> Tracy, California 95304 MAR 0 9 2021 <br /> SR0083278 ENVIRONMENTAL HEALTH <br /> DEPARTMENT <br /> SUBJECT: Soil Suitability/Nitrate Loading Study Addendum <br /> Reference is made to the project indicated above. The EHD has a question regarding the denitrification <br /> factor used in the Nitrate Loading Study for this project. A 60%denitrification percentage was used in the <br /> loading equation which is a higher figure than what is seen in the Studies of other consultants. <br /> This 60%figure was correlated with data obtained from the Tracy Islamic Center(TIC)project I completed <br /> in June 2009, approximately 650 ft to the north of the subject project. I retrieved surface and deep <br /> subsurface soil samples from the TIC project, conducted applicable chemistry on these samples, and <br /> observed a significant decrease in nitrate-nitrogen concentrations with increasing depth. <br /> The TIC project revealed a 90%reduction in nitrate-nitrogen concentration(11 ppm to 2 ppm)observed in <br /> the chemistry test results. The soil types in which this denitrification occurred is similar to the subject <br /> project soil type,as illustrated below in Table 1. <br /> TABLE 1 <br /> SOIL PROFILE CHARACTERISTICS AND <br /> ANALYTICAL TEST RESULTS <br /> SAMPLE I.D.DEPTH SOIL TEXTURE SOIL NITRATE- pH AND <br /> CLASSIFICATION NITROGEN CATION EXCHANGE CAPACITY <br /> AND SAND SILT AND CONTENT In meq/100g <br /> CLAY PERCENTAGES <br /> FILTER BED Clay Loam <br /> DISPOSAL AREA 35% 30% 35% 2 pprn NU;-N 8.9 25.9 meq/100g <br /> (SR0083278) <br /> TIC FILTER BED Clay <br /> DISPOSAL AREA 22% 30% 47% 11 ppm NO3-N 8.2 69.9 meq/100g <br /> 3.5 FEET DEPTH <br /> (3.5FT) <br /> TIC FILTER BED Sandy Clay Loam <br /> DISPOSAL AREA 50% 24% 25% 2 ppm NO,-N 8.4 27.0 meq/100g <br /> 11.0 FEET DEPTH <br /> (11FT) <br /> Page 1 of 2 <br /> P.O.Box 3794 ❑ Turlock,CA 95381 ❑ 209.402.1652 ❑ ddchesney(a charter.net <br />