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KI KL ElNFELDER <br /> over theavel. Under er the observation of a sanitarian from the SJCEHD, the last 30-minute <br /> reading of the four-hour period was recorded and used to calculate the percolation rate in <br /> minutes per inch. The estimated percolation rates are summarized below. Copies of our field <br /> percolation test results for test numbers P-1 and P-2 are attached. <br /> ' 3 H 'Itt � ValrhQEaIe(m� lich)a <br /> 77 <br /> P-1 3.5 Did not percolate <br /> P-1 9,0 Did not percolate <br /> P-1 15.0 Did not percolate <br /> P-1 19.0 2 <br /> P-1 25.0 36 <br /> k P-1 (retest) 3.5 63 <br /> P-1 (retest) 10.0 Did not percolate <br /> P-2 3.5 25 <br /> P-2 12.5 28 <br /> P-2 20.0 31 <br /> Following our percolation testing in December 2001, a representative with our firm obtained a <br /> sample of groundwater using clean procedures from the well Iocated on 10834 Copperopolis <br /> Road (northern parcel). The same day, the water sample was submitted to Far West Laboratories <br /> using chain-of-custody procedures for DBCP and nitrate testing. The results of our tests and a <br /> copy of the chain-of-custody are attached. I <br /> NITRATE LOADING CALCULATIONS <br /> Per San Joaquin County Environmental Health Division (SJCEHD) requirements, the following <br /> summarizes our nitrate loading calculations for the proposed leach field. The drinking water <br /> standard for nitrate is 45 milligrams per liter (NOO and 10 mg/1 as Nitrogen (N) in groundwater. <br /> In our evaluation of nitrate loading, we have used the Hantzsche mass balance equation (source: <br /> Predicting Ground-Water Nitrate-Nitrogen Impacts, Hantzsche and Finnemore (1992)), which is <br /> presented below with an explanation for each factor and the value used in our study. The <br /> selection of parameters was based on previous studies and investigations performed by our firm <br /> and others, San Joaquin County Sewage Standards, and information provided in a report dated <br /> March 19, 1997 prepared by the Questa Engineering Corporation and authored by Mr. Hantzsche <br /> for a development in the Stockton area. <br /> N� =AWN,,S1-D) + N_bZ <br /> AW+r <br /> Where: <br /> N, = Average calculated nitrate-nitrogen in groundwater resulting from domestic sources <br /> and precipitation—mg/l, as N <br /> 204684-01.GO 1/ST02R731 <br /> ©2002 Kleinfelder,Inc. November 5,2002 <br /> Page 3 of 5 <br />