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As referenced in the Soil Suitability Study Section, the on-site domestic well was analyzed for nitrate and found to be 70 ppm which is 25 ppm over the drinking water maximum contaminant level. It has been determined from documents at the County Environmental Health Department, that the well is 215 feet deep, with a 100-foot grout seal. The well was constructed as an open bottom well whereby it draws water from one specific aquifer. This aquifer has been impacted by nitrates from an upgradient source. V. PROPOSED SEPTIC SYSTEM LOADING AND OPERATIONAL DESIGN The final design of the septic system for the proposed project will be completed by the engineering firm of SKW & Associates of Modesto. The following information is based upon Environmental Health Department requirements: It is our understanding the Sant Nirankari Mission meets only on Sundays and this will also be the case for the new Mission. According to plans, there are to be 210 seats and no kitchen facilities in the new Mission. The total anticipated wastewater flow every Sunday will be: 210 Parishioners x 5 gals/person= 1,050 gallons (Average Daily Flow -ADF). The Calculated Tank Capacity(CTC) is as follows: Base Tank Capacity (BTC) = 1200 gals + 1050 gals ADF=2250 gals CTC. Therefore, a 2000 gallon septic tank must be used. Leachline requirements are as follows: 2250 gals CTC x 0.250 soil factor= 560 lineal feet of leachline, two feet wide (use 600 feet).. This equates to a 6,000 sq. ft leachfield area, which must be doubled for a 100% replacement area, for a total leachfield area of 12,000 sq. ft. 7 v Ao� �-"- '—f— C Sy S-t�, Additionally, there must be at least a five-foot minimum distance between the bottom of the leachlines and the highest anticipated depth to groundwater. This five-foot distance requirement provides an unsaturated vadose zone where high rates of biological, chemical and physical treatment of the wastewater can take place. Since the current groundwater is at approximately 7.5 feet below the leachfield area, the leachlines should be placed at a depth of 24 inches below grade. M ACX 1 ww In addition to estimating wastewater loading rates, climatic stress must also be considered regarding the loading of the septic system. Leachfields must transmit two hydraulic loads: the effluent load and the climatic load during the rainy season. The average yearly rainfall in the Tracy area is 12.50 inches which is significant enough to influence hydraulic loading. When soils with hydraulically limiting horizons (such as clays or a high groundwater table) are used for disposal, hydraulic stress occurs when the total effluent load plus precipitation exceeds the transmission rate through the limiting horizon. During the rainy season, both climatic and effluent loads may have to be stored above this limiting horizon. If the subject leachfield contains inadequate storage capacity, which is a possibility, it will eventually fail by surfacing effluent during climatic tress f4 j z (�-(va e,t,t rao ,•�j a cw. c,. v�C I I i v a`�°► Ldolo f = z a a Vaffey Ag Pfsearck