Technologies and Costs for Removal of Arsenic From Drinking Water

the labor rates for both large and small systems may be very conservative and that actual laborrates may be much lower.17. O&M Costs were calculated using the data on regeneration dose, regeneration frequency,labor hours per week and adjusted labor rates using the equation in the Very Small SystemsDocument.Basis. The equation allows the critical variables to be used to estimate O&M costs. Theequation produces O&M cost in cents per thousand gallons, so it must be converted to dollarsper year. Run lengths of 700 BV and 1500 BV were included in the November 1999Technology and Cost Document (2). The O&M costs produced by this costing procedure areconsistently higher than those in the November 1999 Technology and Cost Document even atthe higher flow rates. This is true for both run lengths. Even though the equation in the VerySmall Systems Document listed a domain up to 0.27 mgd, it appears to function over the entireflow range.E.3 WASTE DISPOSAL COSTS18. The primary waste is the regenerant brine stream. Since arsenic in the brine stream wouldlikely exceed the toxicity characteristic regulatory level of 5 mg/L, it could be consideredhazardous waste. Any mixture of domestic sewage and other wastes that passes through asewer system to a publicly-owned treatment works for treatment is excluded from being solidwaste and thus can’t be hazardous waste. Discharge to a POTW is the only waste disposaloption being considered for anion exchange brine.Basis. The proposed rule listed three mechanisms to dispose of the brine stream used forregeneration. The options were: sanitary sewer, evaporation pond, and chemicalprecipitation. Many comments on the proposed rule were concerned about waste streamsbeing considered hazardous waste. Waste streams containing less than 0.5% solids areevaluated against the toxicity characteristic directly to determine if the waste is hazardous.E-10