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V. CONCLUSIONS AND RECOMMENDATIONS NLS§ 4.1, 4.2., As referenced on Page 6, the nitrate loading calculations theoretically demonstrate an exceedance of the MCL by 2.2 mg/L NO3-N. Also as referenced, the effluent system for the HOP facility is composed of two separate disposal structures (leachlines and a large sump structure) that can be switched back and forth between the two structures by a bull-run valve that is located directly north of the septic tank. As illustrated in Appendix G, Richard's Pumping and Excavation Service, Inc. excavated above one of the leachlines revealing a substantial root system from the surrounding trees. Although root systems can create problems with effluent disposal, there are several materials on the market that mitigate root intrusion into leachlines. Richard's Pumping can monitor this potential and take corrective action, if needed. The Water Balance Analysis for the Stockton area illustrates the adjusted Et (evapotranspiration adjusted with 0.6 Landscape Coefficient multiplier) for the six months of April through September, totaling 24.19 inches. The volume rate of wastewater entering the soil averaged over the gross developed area was calculated to total 23.14 in/yr or 1.93 in/mo. During the warm and windy months of April through September, approximately: 1.93 in/mo x 6 mos. = 11.58 inches of effluent can be theoretically transpired by the extensive root system, leaving 24.19 - 11.58 = 12.61 inches of domestic irrigation water to be potentially evapotranspired (Et) also by the trees and lawn grass during these warm/windy six months. Since most of the remaining nitrate loading parameters (i.e., the total nitrogen concentration of wastewater, the denitrification factor, and background NO3-N) should not vary dramatically, the 11.58 inches of transpired effluent can be removed from the total volume of wastewater entering the soil: 23.14 - 11.58 = 11.56 inches of effluent may now be entering the soil since this volume will be discharged through the sump structure with very little-to-no Et and nitrification, during the colder six months of any given year. The nitrate loading calculation now becomes: 11.56 in/yr (67.4 mg NIL) (1 - 0.75) + (8.82 in/yr x 0.1 mg/L) Nr = (11.56 in/yr + 8.82 in/yr) Nr = 9.6 ppm as nitrate-nitrogen (NO3-N) or 42.7 ppm as nitrate (NO3) Therefore, to mitigate the nitrate loading and bring it under the MCL, it shall be a requirement that the effluent be diverted to the leachline structures during the warmer months of April through September, then switch the bull-run valve so effluent flows to the sump structure during the cooler six months of the year. Since Richard's Pumping Service pumps the septic tank approximately every three months, the service technician can switch the bull-run valve accordingly and monitor effluent flows during the time the effluent is diverted to the leachlines. Page -8- Chesney Consulting