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w w <br /> Sy= specific yield of receiving soil in percent <br /> t =time since the beginning of wastewater application in days <br /> Substituting known constants for the variables, we find the following: <br /> Q = 1,000 gpd-7.48 gals/ft' = 134 ft' <br /> /day <br /> A = 1,600 ft' (See Section IV C.) <br /> C=Length to width ratio= 1, therefore, C=3.4179 <br /> L=35 ft <br /> K=Using vertical permeability as most conservative=8.5 cm/hr x 24 hr/day x 0.0328 ft/cm=6.7 ft/day <br /> h= 15 (See above) <br /> n=Length to width ratio= 1,therefore,n= 1.7193 <br /> Sy=27% (coarse sand) <br /> t =3,650 days (10 yrs) <br /> Zm =0.286 x 41.65 x 0.0190 x 3.79 = 0.86 ft <br /> It appears that the maximum mound height that may occur under the filter bed, and above the <br /> current static water table depth is 0.86 feet after 10 years of effluent application. This maintains <br /> an acceptable distance of approximately eight feet between the soil/effluent interface and the top <br /> of the mound (11 ft to water table minus 2 ft depth of filter bed minus 1.0 feet mound rise= 8 ft <br /> separation distance between soil/effluent interface and top of effluent induced mound). For <br /> wastewater treatment to occur,the distance effluent must travel through the soil environment <br /> under unsaturated conditions is generally regarded to be five feet. Wastewater treatment in this <br /> respect is taken to be destruction of bacteria and viruses. <br /> If it is determined at some time in the future that mounding effects are preventing proper effluent <br /> treatment and disposal, the additional area may have to be activated. This may occur prior to <br /> attaining a 1,000 gpd effluent flow volume, but is unlikely. <br /> IV. SEPTIC SYSTEM OPERATIONAL CRITERIA AND DESIGN <br /> A. Anticipated Wastewater Flow Volumes <br /> EHD uses a number of criteria to project wastewater flow volumes,typically based upon Published <br /> Sewage Standards Data: 1.) 15 gals per industrial employee and customers per day, 2.) The number <br /> of bathroom fixtures, or bedrooms (e.g., 150 gal/toilet fixture for store employee/public use), 3.) <br /> The number of parking stalls, and/or 4.) Historical wastewater flow data for a similar facility that is <br /> comparable to the new facility. The following Chart illustrates wastewater flow using each of these <br /> applicable parameters: <br /> Page-6- <br /> Chesrrey Consufting <br />