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December 16,2002 , Job Number_: LG02�213 Page 11 ; Table 6. Suinmary of Nitrate Mass Balance Analysis: ." Result Acres- ;Average• Effluent Denitrification(d) Deep Percolation. (Ne) .(A) Daily Concentration of Rainfall(R) " (Plate 9) Flow(Q) (Nw•) (Plate 8) (Table 6) 4.0 mglL-N' 16.7 657 gpd " 45 mg/L-N ,, 10% 5.01 in *Note:Maximum contaminate level(MCL)for Nitrate is 10 mg/L-N and 45 mg/L as NO,. Please note that Nw ..(nitrate waste level of sewage)of 45 mg/L-N is not related to the nitrate drinking water MCL of 45 mg/L as NO3. VIII. CONCLUSIONS AND RECOMMENDATIONS In conclusion, a rapid percolation rate of less than 1.7 min/inch`was"measured within the percolation test boring.' Our office encountered loose sandy soils to a total depth of 1:0 feet during our field investigation. The depth to ground water.at the.site'was 23 feet according"to the most recent ground water depth maps. The nitrate level ineasured from'the onsite domestic well indicated high concentrations in the ground,water. The nitrate level measured"in the well was . collected and'tested.two..(2) different times and was found to be 77 and 120 mg/L as NO3. The Environmental Protection,Agency rhaximum contaminate level for drinking water for nitrate as NO3 is 45 mg/L(or 10 mg/L as nitrogen N). A nitrate plume in the ground water appears to exist -within the local area.which probably.originated from the use.of septic systems, agricultural, e ,fertilizers, or possibly'dairy.activities or a combination of the uses. _- The geologic map and soil maps of the local area indicate these sandy conditions also exist throughout the-area. The ground"water 'map indicates that shallow ground water exists throughout the area. It.is'well known that for sandy,soils of high permeability combined:with the g Y ,. shallow depth to ground water, the shallow aquifer is susceptible to.nitrate impacts from human '. ! . activities. , Lo ecause of the sandy conditions, the rapid percolation rate measured, the shallow depth water, and the pre-existing nitrate condition of the ground'watez, we recommend the engineered se tic system to reduce nitrates of t ewa e effluent. Since the nitrate alance indicated minimal long term impacts due mainly to the size of the"property, we r lieve that longterm verification monitoring is warrantied for this project. The ndations for the project areas follows: