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Thornton On-site Waste Water Feasibility Study Page 8 of 9 Our Project Number: 2017-00010 December 1, 2017 The base tank capacity for the proposed project, as discussed above, per the SJC standard size for the base tank capacity (BTC) of a commercial establishment is 1125 gallons when over 1500 gallons. The average daily flow is 6,089 gallons per day. A soil factor of 0.225 for silt and or sandy cla r�loam is considered appropriate based on the permit and soil survey review data. The total lineal feet of leach line required is calculated below: 1125 BTC + 61089 ADF = 7,214 CTC 7,214 CTC x 0.225 Soil Factor = 1,623.15 lineal feet of leach line (two feet wide) The leach line dispersal field requires a maximum length of 100 feet per leas I ,ie 3,-,d 10 feet between each leach line. Assuming there would be 100-foot length leach lines, this would amount to sixteen (16) leach lines; the SJC OWDS call for a distance of 10 feet distance between leach line, therefore, a minimum of 16-leach lines with a required distance of 10 feet between amounts to approximately 15,000 square feet of space for the dispersal field. Based on this method for calculating leach line requirements, the dispersal field would require approximately 15,000 square feet. The SJC OWDS call for an additional 100 percent of the initial land area required by the original onsite wastewater treatment system leach field to be available for expansion in case of failure. Based on the 15,000 square feet required for the initial dispersal field the 0.55 acr%24,000 square foot lot is ,not large enough to accommodate the 100percent exexpansion rewired.,However, general engineering measures can be utilized in order to reduce the length of the leach lines, increase surface area within proposed trenches, and or reduce flow values through restriction measures. In addition, other systems such as filter beds, and/or modifications for_closer spaced leach lines would allow for sufficient spagp. Based on this information, and or experience in the area, there are measures available to design a system that will fit the space limitations of the parcel available for the proposed leach field. The proposed septic system is located in an area with a known high-water table. Per Gui- initial septic permit review the distance to groundwater was 10 feet below ground surface at the planned location. Per the OWDS, in areas of known high ground water tables, a subsurface boring or trench shall be completed to determine the depth of the water table. If the water table does not allow for a minimum of a five (5) foot separation between the bottom of the trench and the groundwater table, an engineered mound system will be recommended. t Gletraloylx Eng ineering,Inc. 2,6575 Bruell a Rood,Galt.Ca 95h32 12041-400-5729 4�2C>r5 K mnv.pMralogix,c�-n _z61;��ru