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FReference <br /> Analysis <br /> made to the encountered groundwater from the geotechnical investigation t 7 et <br /> ng grade. This depth to groundwater can be considered very shallow andduce a <br /> known as the "mounding effect"in which percolating effluent encounters the water <br /> rictive stratum and cannot disperse laterally in a certain time frame. Consequently, a <br /> mound forms under the disposal field creating saturated flow conditions and decreasing the <br /> distance the effluent must travel under unsaturated flow for effluent treatment to occur. An <br /> equation developed by Finnemore and Hantzsche(1983) is used below to predict the long-term <br /> maximum rise of the mound: <br /> h=H+Zn-2 <br /> where: h=distance from boundary to mid-point of the long-term mound, in ft <br /> H=height of stable groundwater table above impermeable boundary, in ft ' <br /> Z.=long-term maximum rise of the mound, in ft <br /> Substituting known and estimated values for the variables,we find the following: <br /> H=The height of stable groundwater above an impermeable boundary is estimated to be 4 ased upon the <br /> measured standing water depth in thewell. Therefore, it will be assumed that a boundary ists at H=7 - <br /> 4(Highest measured water table depth)�3 . Long-term maximum rise of mound is estimated at 0.5 ft. <br /> Therefore, It=3 +(0.5 _2)=s <br /> 7 _ ( "4 1n )O.So �.0.50 <br /> Kh <br /> where: Q=average daily flow in ft /day r <br /> A=area of disposal field in ft' <br /> C=mounding equation constant ' <br /> L=length of disposal field in ft ' <br /> K=horizontal permeability of soil in ft/day <br /> n=mounding equation exponent <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 =375 gpd(From Max. flow volume calcs.,Page 12)_7.48 gals/ft=50 ft'/day' <br /> A =2,550 ft'(From mound system sizing calcs,Page 17) <br /> C=Length to width ratio = 2.8,therefore,C= 1.1348 <br /> L=85ft — <br /> K=Using average vertical permeability as most conservative= min/in: 1440 min/day= 15 min/in=8 ft/day <br /> h=3.25 (See above)' <br /> n=Length to width ratio =3,therefore,n= 1.7716 <br /> sy=7% - <br /> t =3,650 days(10 yrs) <br /> Zm =0.02225 x 224.67 x 0.055798 x 2.043 0.57 ft) <br /> 8 <br /> Chesney Consulting <br />