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• not long after the warranty period When removing the pump and motor for motor repair, the pump is also serviced (wear rings, bearings, etc ) as necessary The pumps themselves have held up well It costs about $3,000 to pull the pump / motor assembly, about $1,000 to service the pump, about $5,000 to replace the motor, and about $3,000 to re-install the pump / motor assembly, for a total cost of about $12,000 4 1 5 3 Air Strippers The air strippers are consistently reducing TCE levels to below detection limits (less than 1 ppb) The strippers were designed to reduce TCE levels from of 250 to 0 78 ppb However, since 1995 influent TCE levels have been between 20 and 30 ppb SHMP is currently being fed upstream from the strippers to prevent precipitation in piping and injection wells (see Sec 4 2 3 3 Sequestration of Inorganic Precipitates) However, even before SHMP was being used, scaling or fouling of the stripper packing was not found to be a problem And there has not been evidence of scaling or fouling of the stripper packing since the use of the SHMP was initiated 4 1 5 4 Piping There have not been recent problems with the piping, however, prior to the addition of the SHMP, scale collected in the piping near the injection well head, especially at the valves This accumulation had to be removed by hand 4 1 5 5 Chemical Peed System A chemical feed system is being used to feed SHMP into the process stream through injection ports between the transfer pumps and the air strippers The SHMP being used is a Calgon product (CL-50), and is delivered to the site as a concentrated solution in plastic containers The feed-rate is not automatically regulated based on the flow rate of water being pumped to the strippers, but is adjusted manually if there is a significant change in influent flow rate The target concentration for SHMP in process water is 8 mg/L Although SHMP could be added downstream from the air strippers, it was more convenient to locate the feed system inside the treatment plant building 4 1 6 Components or Processes that Account for Majority of Costs 4 1 6 1 Electricity Electricity costs approximately $500,000 per year (5 1 - 5 2 cents per kW- hr) 4 1 6 2 SHMP Costs for SHMP now exceed $200,000 per year • 4 1 6 3 Labor The staff consists of a manager and a staff of three with an estimated annual cost exceeding $300,000 4 1 6 4 Chemical Analysis Sampling of approximately 45 monitoring wells occurs semiannually Treatment plant influent/effluent, and individual extraction wells concentrations are determined quarterly Analysis includes VOCs by methods 8010 aIId 08020 acid l.liromiwri by riicuiou 6010 Estimated annual cost for these analyses is $15,000-20,000 The existing staff conducts sampling 4 1 6 5 Welland Pump Maintenance Pump motors require replacement approximately every two years At a cost of$12,000 per well and assuming that seven extraction wells require work each year, the total cost per year is approximately $85,000 06/07/99 Page 7 of 14