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Mr.Raymond Vaz December 14,2001 a i Page 3 Nitrate Loading Analysis To determine the general nitrate concentration of the soil, a soil sample was collected and submitted to FGL(analytical laboratory) for general soil suitability analysis(see attachment). The sample was collected at a depth of 3 feet on parcel 7 within the percolation test boring. The result indicates that the nitrate in soil was found to be 5.0 ppm as NO3. This concentration is within normal soil concentration of Nitrate. A ground water sample was also collected on May 11, 2000 from an onsite well for testing of DBCP and Nitrate. Test results are presented in the original Soil Suitability Study report and indicated that DBCP was found to be non-detectable and nitrate was found at 29.3 zewj mgll as NO3 (equivalent to 6.5 mg/1 as N). The DBCP detected in the ground water was non- detectable and below the maximum contaminate level of 0.02 ug/l. The nitrate detected in the ground water was reported as NO3 and is below the maximum drinking water standard of 45 mg/l. Both grab sample tests for soil and ground water do not appear to have excessive concentrations of nitrogen. Because of the concern of nitrate leaching into ground water from septic systems, a nitrate loading analysis was required by the San Joaquin County Public Health Services, Environmental Health Division, (PHS-EHD). If the proposed development is disposing of septic effluent to land,ground water quality may be impacted to some degree. Nitrate sources considered for this project are percolating septic effluent from a residence constructed on each of the four 5-acre arcels and deep percolation of rain water contamin nitrate. �7,1,i/G DCS+/ arm` e method utilized in the nitiffe loading analysis is bas on a simple mass balance formula, discussed in a published article by Hantzsche and Finnemore,' which provides a convenient and simplified method to estimate long-term ground-water nitrate impacts on an area- wide basis. Hantzsche and Finnemore found that over a long period of time, water quality in the upper saturated ground-water zone closely approximates the quality of percolating recharge waters. They believe that their method is a good planning tool and provides useful information to planners and local officials but with some real limitations. In their article published in Ground Water, Hantzsche and Finnemore mention that"...the equation ignores dispersion, lateral flow„r.)a 7 and mixing with ground water flow from up-gradient areas. These processes would generally contribute to additional reduction of nitrate-nitrogen concentrations in ground water to the extent t Haatzshe N.N.,Finnemore,E.J. 1991,Predicating Ground-Water Nitrate-Nitrogen Impacts. Ground Water,Vol.30,No.4. pE�Spy 4 i O ISSOC\