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i Resultant Recharge(Nr)from the Gas Station and Convenience Store exclusively is at the Maximum Contaminant Level(MCL)for nitrate-nitrogen of 10 ppm. 5.3 Crites / Tchobanoglous Formula (Phase 1 & Complete Build-Out) LN = Lµ,CNF where: LN = nitrate-nitrogen loading in lbs/ac-day LW = wastewater loading in gals/ac-day= 25,830 gals/day= 11 ac=2,350 gals/ac-day CN = nitrogen concentration: average determined to be 87 mg N/L F = conversion factor: 8.34 lbs/[106 gal-(mg/L)] LN= 2,350 gals/ac-day x 87 mg N/L x (8.34)(10-6) = 1.71 lbs N/ac•day x 365 days/yr= 622.4 lbs N/ac/yr. The disposal area could be a maximum of 3.1 acres. Therefore,the Crites/Tchobanoglous Formula nitrate-nitrogen loading is approximately 622.4 lbs N/ac/yr x 3.0 acre =1,870 lbs N/yr. Comparing the Hantzsche/Finnemore Equation with the Crites/Tchobanoglous Formula by using the results from the Hantzsche/Finnemore Equation of 50.5 ppm NO3 N (223.6 ppm NO3): 50.5 ppm nitrate-nitrogen x 2.72 (conversion factor) = 137.4 lbs N in an acre-foot of water. 9,428,000 gallons wastewater/yr '. 325,851 gals/ac-ft water=28.9 ac-ft of wastewater disposed/yr x 137.4 lbs N/ac-ft= 3,975 lbs N/yr according to the Hantzsche/Finnemore Equation. Therefore, the Crites/ Tchobanoglous Formula predicts approximately 2.1 times less (approx. one-half) nitrate-nitrogen loading (in terms of lbs N/yr) than predicted by the Hantzsche/Finnemore Equation (1,870 lbs N/yr vs. 3,975 lbs N/yr). ! 5.4 Kaplan Parallelepiped Method (Phase 1 & Complete Build-Out) NLS§3.6 Assumptions: 1.) The entire concentration of Total Nitrogen (87 ppm) is completely nitrified and percolates to the water table, 2.) Water table depth of 22 ft, and a 15 ft mixing layer thickness of the first aquifer, 3.) Porosity is 33%, 4.) The entire length(N-S) of the disposal area is used (250 ft), 5.)No nitrogen input from on-site landscape fertilization or indigenous soil nitrogen, 6.) Water table Darcy velocity has been calculated on Pg. 12 to be 1.0 ft/day, 7.) Groundwater flow direction is due north. Volume of dilution: 250 ft length x 15 ft depth mixing layer x 1 foot/day x 365 days/yr x 1 m'/35.3 ft' = 38,775 m'/yr=38,775,000 kg water/yr x 33%porosity= 12,796,000 kg water/yr. Amount of Nitrate: Taking the average of the lbs N/yr as determined from the Hantzsche/Finnemore Equation= 3,975 lbs N/yr x 0.4536 (conversion factor) = 1,803.1 kg N/yr Increase in Mixing Laver Concentration: 1,803.1 kg N_ 12.796 million kg water= 140.9 ppm NO3-N (624.0 ppm NO3). The increase in mixing layer nitrate concentration as predicted by the Kaplan Method is 2.8 times greater than the Hantzsche/Finnemore Equation determination (140.9 ppm N0;N vs. 50.5 ppm NO3-N)' Page -21- Chesney Consulting