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.k f l: OP_ Pk k" KLEINFELDER F . Nb = Background nitrate nitrogen concentration of rainfall recharge at the water table = F10.5 mg/l (per Technical Memorandum, Hydrologic and Soil Investigation for the Chico Urban Area,page 6, Dames and Moore, April 1996) � 2 Our calculation is as follows: !17 1 Ne = 0_40(2)(70)(1 —0.15) +0.5(6.7) = 47.6 + 3.4 = 6.8 mg/1 as N 0.40(2) + 6.7 0.8 + 6.7 F1 8. CONCLUSIONS ' The results of our percolation tests indicate that a suitable soil percolation stratum exists at the percolation test location at a depth of about 3 feet below existing site grade. A suitable soil condition for septic percolation tests is defined as a stratum capable of percolating water at a rate of 60 minutes per inch (min/inch) at a depth of up to 3.5 feet below existing site grade. Based on these results, it_isour professional ..op 'on-that the proposed septic tank/leach trench sewage ------------ dispo5a1 system should adequately serve the proposed structure. We do not antici fora e�age�ere or a1 er i tiv 's tic ss m,� F1 As discussed, we calculate 6.8 mg/l of nitrate-nitrogen (N) in groundwater resulting from the 11 proposed leach fields, a result that is below the state drinking water standard of 10 mg/l. Based I on this level of nitrate-nitrogen, we anticipate that the impact on surrounding wells will be minimal. The Upper Main Canal is the nearest water body to the site and is located about 2 F miles to the southwest. Based on the distance from the canal to the site, we anticipate that the impact to water bodies will be minimal. 9. LIMITATIONS 1 Kleinfelder has prepared this report in accordance with the generally accepted standards of care F 1 that exist in San Joaquin County at the time of writing. It should be recognized that definition and evaluation of geologic and chemical subsurface conditions are difficult. Judgments leading F1toconclusions and recommendations are generally made with an incomplete knowledge of the subsurface and/or historic conditions applicable to the site. The conclusions of this report are based on the information provided regarding the existing and proposed development and on-site conditions as well as our field observations, percolation test results, and experience in the project area. It was assumed that the percolation test results are representative of the subsurface conditions in the general area. No warranty, expressed or implied, is made. F1Regulations and professional standards applicable to Kleinfelder's services are continually evolving. Techniques are,by necessity, often new and relatively untried. Different professionals �^ may reasonably adopt different approaches to similar problems. Therefore, no warranty or j guarantee, expressed or implied, will be included in Kleinfelder's scope of service. •F 38058.GO1/ST04R650 May 14,2004 ©2004 Kleinfelder,Inc. Page 5 of 6 Fj