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` GEOTECHNICAL <br /> NEIL U. ANDERSON ENVIRONMENTAL <br /> A N D A S S O C I A T E S INSPECTIONS & TESTING <br /> LABORATORY SERVICES <br /> POOL ENGINEERING <br /> POST TENSION DESIGN <br /> March 12,2004 <br /> NOA Project Number: LE03-465 n CIE(,� IE�\ <br /> Send Via U.S. Mail and Fax: (209) 464-0138 �f,] (J v U <br /> MAR 1 5 2004 <br /> Mr. Mike Huggins, Supervising R.E.H.S.,R.D.I. <br /> San Joaquin County Environmental Health Department ENVIRu divl pt=Q"^ITiSERER HEALTH <br /> VICES <br /> 304 East Weber Avenue,Third Floor <br /> Stockton, CA 95202-2708 <br /> Subject: SOIL SUITABILITY NITRATE LOADING STUDY <br /> 3269 EAST TOMAHAWK DRIVE <br /> STOCKTON,CALIFORNIA <br /> Dear Mr. Huggins, <br /> Per our telephone conversation today,you mentioned after initially reviewing the subject report,you <br /> were concerned that the Nw value appeared low. Also,we discussed whether the project could <br /> potentially impact drinking water quality. <br /> I have attached a table from Crites and Tchobanoglous textbook titled Small and Decentralized <br /> Waste Water Management Systems which I have been recently using on related projects. The table <br /> indicates the total nitrogen level (Nw) for domestic waste water ranges from 20 to 85 mg/L-N with <br /> a typical value of 35 mg/L-N. This is the value selected for this project. <br /> Our office has typically used values between 35 mg/L-N to 45-mg/L-N depending on the use <br /> permit. With the use of large septic tank sizes,the Nw value of 35 mg/L-N seems reasonable. <br /> Please see the attached table from Crites and Tchobanoglous. <br /> It is worth mentioning that a typical denitrification value of 25%was selected for this project. After <br /> reviewing the nitrate balance, a case for 35%could be made reflecting the fine-grained surface soils <br /> at the site. <br /> I recall that we have discussed on numerous occasions the absence of ground water impacts from <br /> septic system in ground water below Morada area developments. A great many of the Morada <br /> homes were built in the 1940's thru the 1960's. I believe we share the view that the lack of any <br /> impact is probably due to the nature of the fine grained surface soils which exist in that part of the <br /> County and the depth to ground water. We have confirmed that fine-grained soils exist below the <br /> subject site and the depth to ground water is fairly deep (about 83 to 92 feet). <br /> LODI ■ SACRAMENTO ■ MODESTO <br /> ENVIRONMENTAL DIVISION 902 Industrial Way,Lodi,California 95240 ■209.367.3701 0 209.369.4228 ■www.noandersonxom <br />