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II. SANITARY DESIGN CALCULATIONS • <br />Hydraulic and Organic Calculations <br />Hydraulic <br />Showers <br />250 people/day x 3.33 gal/minx 8 min/person = 6, 600 gpd <br />Toilets <br />8 toilets x 200 gpd/toilet = 1,600 gpd <br />Sinks <br />8 sinks x 50 gpd/sink = 400 gpd <br />Fountains <br />2 fountains x 20 gpd/fountain = 40 gpd <br />TOTAL 8, 700 gpd <br />Runoff Period = 16 hours <br />Organic <br />BOD (5 day) <br />250 people/day x 0.083 lbs(1)/person/day = 20.75 lbs/day <br />Plant Sizing <br />1. Determine air requirements: <br />Use 2,100 cu.ft. of air/lb BOD to be treated. <br />2,100 ft3/lb BOD x 20.75 lbs BOD/day = 43,575 ft3/day <br />43,575 ft3/day x 1 day/1,440 = 30.26 CFM1A <br />2. Determine aeration chamger size: <br />Use a factor of 15 lbs BOD per day per 1,000 cu.ft. of aeration chamber. <br />Volume = 20.75 Ib BOD/15 lb BOD x 1,000 ft3 x 7.48 gal/ft3 <br />Volume = 10,347 gallons <br />3. Determine clarifier tank size: <br />Allow 4 hours retention time of daily flow using a runoff period of 16 hours. <br />Volume = 8,700 gpd x 4 hours/16 hours = 2,175 Gal <br />4. Determine chlorine contact tank size: <br />Allow for 45 minutes of retention time. <br />Volume = 8,700 gpd x 3/4 hour/16 hours = 408 gallons <br />(1) Water Treatment Systems for Rural Communiti.:s; Goldstein and !Moberg <br />-3- <br />