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kn KLEINFELDER <br /> y We do not know of any existing and/or potential groundwater contamination issues in <br /> the project vicinity. There are no existing gas s a Ions or dairies adjacen e <br /> property. A gas tank located in its trunk powers the wind machine located on site. <br /> Seasonal fertilization of the on-site and off-site agricultural land, if performed, and <br /> other septic tank/leach field systems in the project area are probably the largest <br /> contributors of nitrogen to groundwater in the project vicinity. <br /> 5 7. SOIL PROFILE <br /> The subsurface soil encountered in our soil profile boring consisted of silty sand to a <br /> depth of about 6 feet below the existing ground surface, underlain by gravely sand to <br /> the maximum depth explored. A detailed description of the subsurface soil <br /> encountered is presented on Plate 7. <br /> The Soil Survey of San Joaquin County, California published by the U.S. Department <br /> of Agriculture, Soil Conservation Service (1992) refers to the near-surface soil within <br /> the project area as belonging to the Delhi loamy sand soil series (Map Symbol 142). <br /> + This soil is described as having "severe' percolation characteristics for septic tank <br /> absorption. Other attributes are given in the table below: <br /> •- Map Available Water Capacity, H Organic Content, <br /> J< -Symbol Soil Name inches/inch p percent <br /> 142 Delhi loamy sand 0.06 - 0.10 6.1 - 7.8 <1 <br /> + <br /> 8. PERCOLATION TESTING <br /> The results of our percolation tests are presented below. A copy of our field <br /> + percolation test results is attached as Plates 8 and 9. <br /> Test Soil Test Hole Percolation Rate <br /> Number Descriptio Depth ft.) min./inch) <br /> P-1 Silty Sand 3 <br /> P-2 Gravely Sand 7 G� <br /> 9. NITRATE LOADING CALCULATIONS <br /> cif.�:i✓,— �S� O��/ /J/`j //�ir!`t <br /> Per SJCEHD requirements, the following summarizes our nitrate loading calculations C�� <br /> for the proposed leach field. The state drinking water standard for nitrate is 45 y <br /> milligrams per liter (NO3) and 10 mg/I as Nitrogen (N) in groundwater. In <br /> evaluation of nitrate loading, we have used the Hantzsche mass balance equation <br /> (source: Predicting Groundwater Nitrate-Nitrogen Impacts, Hantzsche and Finnemore <br /> (1992)), which is presented below. <br /> L <br /> 43498.G011ST05R1014 September 27,2005 <br /> ` Copyright 2005 Kleinfelder, Inc. Page 4 of 7 <br />