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. PRETREATMENT WORK SHEET A-1 Estimatai Sewage Flows in GPD <br /> 1. FLOW Bedrooms Class I Class II Class III Class IV <br /> A. Estimated �9Pd(see fgure A-1) 2 300 225 180 60%of <br /> measured x 1.5(safet factor� 0 gpd 3 450 300 218 the <br /> B. SEPTIC TANK CAPACITY 1,500 gallons(see figure C-1) 4 600 375 256 values <br /> o �ou 4�u ��+ in me <br /> 2. SOILS(Site evaluatlon data) 6 900 525 332 Ciass I, <br /> C. Depth to restrictin la er- 31'-34" feet 7 1050 600 370 II or II <br /> D. Texture LoamlCla Loam Percolation rate �.5 MPI 8 1200 675 408 cdumns <br /> E. SSF 0.83 ft/gpd(see downsizing or<3ff figure) <br /> F. Land Slope 8 to 12 % C-1 Se tic Tank Ca aci in Gallons <br /> Number of Minimum Capacity with Capacity with <br /> 3. Prcssure Distribution Trench Bottom Area Bedrooms Ca acit Garb.Dis . Dis .and Lift <br /> H. For trenches with 6'of rock below the pipe,Area=Flow(1A)divided by SSF(2E)= 2 a less 750 1125 1500 <br /> 300 gpd x 0.83 ftlgpd= 249.0 ft 3 or 4 1000 1500 2000 <br /> I. For trenches with 12'of rodc below the pipe,Area=Flow(1A)divided by SSF(2E)x 0.8 5 or 6 1500 2250 3000 <br /> 300 gpd x 0.83 fl�lgpd x 0.8 = 199.2 ft 7,8 or 9 2000 3000 4000 <br /> 4. ORGANIC LOADING('►f pretreabnent is 6eing useal) <br /> J. 1. Organic loading=flow(A)x estimated BOD in mglL leaving the Downsizing Chart with 3 ft of Separation <br /> preVeatrnent unit x 8.35/1,000,000 Soil Characterisitcs SSF 8�0 anic Laadin <br /> 300 gpd x 10 mglL x 8.35 /1,000,000= 0.02505 Ibs BOD Perc Rate Soil Tecture SSF Organic Ld <br /> 2. System loading=organic loadi J1 I area(H or I) m i s ft/ Ibs/da!ft <br /> 0.02505 Ibs BOD 1 204.0 il� = 0.0001 <0.1 Coarse sand 0.83 0.0020 <br /> 3. Check system loading rate on chart. Should be less than value. 0.1-5 Medium sand 0.83 0.0015 <br /> Loam sand <br /> 5. ROCK YOLUME 0.1-5 Fine sand 0.83 0.0012 <br /> K. Rock depth below disVibution pipe plus 0.5 foot times bottom area: 6-15 Sand loam 0.83 0.0011 <br /> _(Rock depth+0.5 foot x Area(H,or I) 16-30 Loam 0.83 0.0010 <br /> ( ft+0.5 ft)x � ft= 0 fl' 31-45 Silt loam,silt 1.00 0.0007 <br /> L. Volume in cubic yards=volume in cubic feet divided by 27 46-60 Clay loam, 1.10 0.0006 <br /> K/27=cubic yards 0 I 27= 0 yd3 sandy clay <br /> M. Weight of rock in tons=cubic yards times 1.4 or sil cla <br /> L x 1.4=tons 0 x 1.4= 0 tons 61-120 Clay,sandy 2.50 0.0005 <br /> or sil cla <br /> 6. SYSTEM LENGTH >120 Cla 3.25 0.0003 <br /> N. Select width= �3 ft <br /> 0. Divide bottom area width: H,I)divided by N=lineal feet Sizing Chart with<3 ft of Separallon <br /> 204.0 ft� I 3 fl = 68 lineal feet Sofl Characterisltcs 8 SSF <br /> Perc Rate Soil Tecture SSF <br /> a oam <br /> 7. SYSTEM LLR 16-30 Loam 1.67 <br /> P. Draw a line doumhill though soil Veatment system drawn in layout. 31-45 Sifl loam,silt 2.00 <br /> How many trenches dces it aoss? Add their widths together. 46-60 Clay loam, 2.20 <br /> width 1 +width 2+width 3+...... sandy day <br /> 03 ft + �3 ft + Oft + ft = 6 fl or siR cla <br /> Q. Divide total trench width(P)by SSF(F)=gallons per foot 61-120 Clay,sandy 4.00 <br /> 6 ft / 0.83 ft/gpd = 7.2 gaUft(Should be<12 gellons perfoof) or si cla <br /> >120 Cla 5 <br /> Page 1 of 1 <br />