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Orrs�Ta <br /> sew.w� future upper rock bed Job# <br /> TRCATM6IVT - <br /> P�coa�swwt --, ._.. <br /> University of Minnesota Mound Design Worksheet <br /> Greater than 1°/a Siopes <br /> a F�ow <br /> Estimated 750 gpd(see figure A-f) <br /> or measured i x 1.5(safety factor)= 0 igpd <br /> B. SEPTIC TANK LIQUID VOLUMES <br /> Septic tank capacity 2250 gallons(ses figure G1) <br /> Number of tanks/compartments 0 <br /> Effluent Filter (yes/no) yes <br /> C•1 Septic Tank Capacity in Gallons <br /> Number of Minimum Capacity with Capacity with <br /> Bedrooms Capacity Garb.Disp. Disp.and L�ft <br /> 2 or less 750 1125 :1500 <br /> 3 or 4 �<1000 1500 ;,�'OQD y. <br /> 5 or 6 ��' 1500 ' 2250 �3�0: � <br /> 7,8 or 9 2000 3000 40�0 . `' <br /> �. SOILS(Site evaluation data) <br /> 1. Depth to restricting layer- 2.0 feet <br /> 2. Depth of percolation tests= 12 inches <br /> 3. Texture loam <br /> 4, Soil loading rate(see Figure D-33) 0.60 gpd/ft2 <br /> Peroolation rate 10 MPI <br /> 5. %Land Slope 12.0 % <br /> D. ROCK LAYER DIMENS�ONS <br /> 1. Multiply average design flow(A)by 0.83 to obtain required area of rock layer:Item A x 0.83= <br /> 750 gpd x 0.83 ft2lgpd= 630 ftZ <br /> 2. Determine rock layer width =0.83 ft`/gpd x Linear Loading Rate(LLR)(see LLR chart <br /> 0.83 ft2lgpd x 12.00 = 10.0 ft <br /> LLR Chart <br /> Perk Rate LLR <br /> <120 MPI <=12 <br /> >=120 MPI <=6 <br /> 3. Length of rock layer=area divided by width= <br /> 630.0 ftZ / 10.0 feet= 63.0 ft <br /> E. ROCK VOLUME <br /> 1. Multiply rock area by rock depth to get cubic feet of rock <br /> 630.0 X 1.0 ft= 630.0 ft' <br /> 2. Divide ft3 by 27 ft31yd3 to get cubic yards <br /> 630.0 ft3 I 27 = 23.3 yd3 <br /> 3. Multiply cubic yards by 1.4 to get weight of rock in tons; <br /> 23.3 yd3 X 1.4 tonlyd3 = 32.7 tons <br /> Page 1 of 5 <br />