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�- sides of the holes were scored, and significant loose material was removed from the bottom of the hole. The holes were drilled and prepared before noon on August 3, 2004, in accordance with SJCEHD criteria. Approximately 2 inches of fine gravel was placed at the bottom of each 6' test hole, and the holes were presoaked with a minimum of 12 inches or water at that time. The percolation tests P-2 and P-3 were started at about 7:30 under sunny and warm weather on August 4, 2004, in accordance with accepted guidelines using clear potable water. The 6. percolation test P-1 was started that same day at about 19.00 PM The approximate depth of each percolation test below existing site grade is shown on the following table. The holes did not exhibit sloughing or caving. At the time of testing, no standing water from the pesoaking 6. remained in the holes. From a fixed reference point, a marked location on the side of PVC pipe inserted into each hole, the drop in water level was measured in approximately 30-minute 6. intervals for four hours, refilling as necessary to maintain the prescribed amount of water over the gravel (SJCEHD Procedure #2). Due to the rapid percolation rates in percolation test holes at P-1 and the deeper test hole at P-3, readings toward the latter portion of the four hours were taken at 15-minute intervals. However, as specified, the last two 30-minute readings were 6. recorded under the observation of a representative from the SJCEHD and were used to calculate the percolation rate in minutes per inch. The estimated percolation rates are summarized below. A copy of our field percolation test results signed by a representative from SJCEHD is attached. Details of each test can be found on the percolation test sheet. Test Number Performed Depth (feet) Percolation Rate(min./inch) P-1 3.3 6.3 10.0 6.3 •� P-2 3.4 50.0 10.4 7.6 P-3 3.3 25.0 19.4 12.5 7. NITRATE LOADING CALCULATIONS ` Per SJCEHD requirements, the following summarizes our nitrate loading calculations for the proposed leach field. The state drinking water standard for nitrate is 45 milligrams per liter (NO3) and 10 mg/l as Nitrogen (1) in groundwater. In our evaluation of nitrate loading, we r have used the Hantzsche mass balance equation (source: Predicting Groundwater Nitrate- Nitrogen Impacts, Hantzsche and Finnemore (1992)), which is presented below with an explanation for each factor and the value used in our study. The selection of parameters was L, based on previous studies and investigations performed by our firm and others, San Joaquin County Sewage Standards, previous communication with Mr. Mike Huggins with SJCEHD, and information provided in a report dated March 19, 1997 prepared by the Questa Engineering L. Corporation and authored by Mr. Hantzsche for a development in the Stockton area. Current laws allow two homes on each parcel. We present these calculations based on two single- t. L 48524.G01/ST04R1163 September 3,2004 ©2004 Kleinfelder,Inc. Page 5 of 8 r