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08/16/01 THU 16:55 F.a1 [a 005 k'9 KLEINFELt7ER High Estimate N, = 0.3(1.75)(45)(1 —0.1)+1.0(3) = 21.3 +3.0 = 6.9 m-/I as N 03(l.75)+3 0.52 + 3 Average N,= 6.21 rag/1 as N One of the factors that is required by the SICPPIS is to det.ennine the existing value of nitrate in the groundwater below the site. A groundwater sample was obtained for the existing on-site well using "clean" methods. At least 5 gallons of water was first bailed from the well prior to obtaining our earnple. The wator sairple was submitted to Cec►Analytical Lahorataries, hir,. using chain-of-custody procedures to evaluate nitrate as N in accordance with EPA Test Method 300. Results of the test showed a non-detectable nitrate as N concentration. A copy of our test rc,sttlts and chain of custt,dy a1c wtt4,Amd. VvIliru this valor-, is cumbivCd With Our loin and high nitrate-nitrogen (N) in groundwater calculated above, the total nitrate-nitrogen is well below the state drinking water MCL standard. eALQrCrdjngly. we conclude. that placement of the new s.-ptic system on the site should not cause a rise of nitrate levels above State standards. DRAINAGE BASIN There are many factors that influence storm water disposal Clear water was used in our tests, whereas oil residue, silt, organic matter and other deleterious material will likely oe included in the actual storm water. Varations in soil conditions within the basin will also likely affect percolation characteristics. For use in design, a factor of safety on the order of 1.5 to 2 should be applied to ll?rt puQ914:iun rafe5 d51imal-d, The above percolation values apply to drainage trenches or drywells installed in the basins and possibly to the sides of the basins. Depending on the depth of the basins, the design percolation rates for the basin sides should be farther mviewed. Over time, very little percolation should be assumed through the basin bottoms due to silting and organic build-up unless a vigorous program is followed to maintain the basins by frequent cleaning and discing to reduce silt build-up. Subsurface drain trenches andlor drywells should be equipped with filtered intakes. Our representative should be allowed to observe the soils exposed daring construction of the basins and subsurface trenches or drywells in order to confirm that the design rates used are appropriatc for the actual soils encountered. 20-4630-01.G01/2011 R9E6 Page 4 of 5 Copyright 2001 Kleinfelder,Inc. August 16,2001