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<br />SURCHARGE <br /> <br />Every industry that has a BOD above 200 milligræTIs per liter <br />(mg/I)¡ a COD above 450 mg/l and/or suspended solids above 200 mg/l <br />must pay extra strength sewage. The formula for calculating the <br />surcharge is: <br /> <br />S = V x 8.34 [A (BOD-200) + B (SS-200)] or if the COD is <br />than 2.25 times greater than the BOD then the formula is: <br /> <br />more <br /> <br />S = V x 8.34 [C (COD-450) + B (5S-200)] <br />When S : Surcharge <br />V = Wastewater average or actual monthly consumption <br />whichever is less <br />8.34 : a constant <br />A = cost of treating one pound of BOD <br />C.: cost of treating one pound of COD <br />B = cost of treating one pound of SS <br />BOD = Biochemcial Oxygen Demand <br />COD = Chemical Oxygen Demand <br />SS = Suspended Solids <br />200 = Average concentra"tion of SS and BOD in domestic <br />wastewater <br />450 = Average concentration of COD in domestic waste <br />water <br /> <br />Procedure: <br /> <br />Twenty-four (24) hour composite samples shall be collected from <br />each industry that is suspected of requiring a surcharge in accordance <br />with the policy on sampling. These samples shall be analyzed in the <br />laboratory for BOD, COD, and suspended solids concentrations. If the <br />results of the samples taken are not within a reasonable range <br />(usually 10%) an additional composite sample shall be taken. The <br />results of the samples collected shall be averaged and a surcharge <br />factor (S.F.) calculated using one of the follo\iing formulas: <br /> <br />S.F. = [8.34 A (BOD-200) + B (SS-200)] <br />or if the BOD is less than 2.25 times <br />the COD the formula is S.F. = 8.34 <br />[C (COD-450 + B (SS-20Q)] <br /> <br />-61- <br />