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Lo KLEINFELDER N, = 1.1 2 70 1 —0.3 +0.5 9.4 = 107.8 +4.7 r 1.1(2) + 9.4 2.2 + 9.4 Lo 8. CONCLUSIONS The results of our percolation tests indicate that a suitable soil percolation stratum exists at depths of about 3 to 3!/2 feet below existing site grade at the percolation test locations in Lots 1, 5, 6, 7, and 13. A suitable soil condition for tests at this depth is defined as a stratum capable of percolating water at a rate of 60 min/inch or faster. Our tests indicate that in the remaining lots (Lots 2, 3, 4, 8, 9, 10, 11, and 12), suitable strata were encountered at the depths of our deeper percolation tests. A suitable soil condition for tests deeper than 3% feet is defined as a stratum capable of percolating water at a rate of 34 +-• min/inch or faster. Based on these results, conventional septic tank/leach trench sewage disposal systems designed* per SJCEHD criteria should adequately serve the proposed residences constructed on these lots. My see a _pits_should_extend-inxothe more so -that were encountered in our borings and in the passing percolation test holes. As previously discussed, for the proposed residential lots we calculate 4.5 m_g/l of nitrate- nitrogen (I) in groundwater resulting from the proposed leach fields. For the proposed I" comuu_ci a�amd, based on the assumptions discussed above, we calculate 9.6 mg/1 of nitrate- nitrogen (l) in groundwater resulting,-frotfi--thy roposed leach field. These results are below the state drinking water standard of 0 in 1. ased on these levels of nitrate-nitrogen, we anticipate that the impact on surrounding wells will be low. Bear Creek is located within the proposed southern most agricultural parcel, Due to the depth to groundwater (greater than 100 feet), the shallow nature of the creek, and the general groundwater gradient in the study area, we anticipate that the impact to surface water will be low. Based on our results we do not anticipate a need for engineered-systems to be�installed at then � � r . residentiaa cels or at,the. commercial parcel.provided,.our-assumptions are accurate. As stated previously, at the time of this writing the type of development that will be constructed on .L the proposed commercial property is not known. If more toilet fixtures are installed on the retail parcel than we assumed.orrif a restaurant or other t paobsXuenx�t is constructefi_at� uses more water than we assumed, the resulting nitrate loading,could._exceed the state drinking water standard of,10,mg/l,, and an engineered or alternative sew age_disposal Asystem may be required to reduce the loading of nitrates to groundwater. For this reason, if the actual uses are different t�an�assumed, our office should be contacted that we may reey_aluate._the,nitrate. Loading.of the commercial property. 4 55208.GOI/ST05R644 June 1,2005 OO 2005 Kleinfelder,Inc. Page 8 of 9