SITE INFORMATION AND CORRESPONDENCE

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• • Figure 2 The following steps should be taken on a regular basis to reduce the use of oversized motors: Maximum RI Concentrations Overestimate Actual Concentrations During P&T • inventory all pumps,blowers,and air compressors Maz. Rlco ncenira tion 6 • note their power requirements (in horsepower) • to use their manuals and O&M data to compare a le n a e e influent � y rfrom ealm ant plant om their specifications to the actual task E extra clip n w e Its w a • conduct a cost-benefit analysis of replacing y 2 oversized equipment with new equipment or installing a variable speed drive that will allow an operator to control its power usage 0 RI Design & 0&M O&M O&M • replace equipment that demonstrate significant In a Is Ila do n Yr. 1 Yr. 3 Yr. 5 cost savings (i.e., can pay off cost of rim a (ye a rs I replacement in a few years) The concentration of PCE is measured during the remedial investigation and then during O&M. Due to In general, assuming 75%motor efficiency and pumping and the blending of water from different extraction wells and overall mass reduction in ground $0.10/kilowatt-hour(kWh), water,the influent concentration to the treatment plant during O&M is often much lower than the maximum RI 1 horsepower = $70/month concentration observed in the aquifer. The cost savings of replacing a large blower for a smaller, more efficient one is shown in Example 3. determine if components are oversized. As shown in Example 4,conducting a cost-benefit analyses will help determine if it is cost-effective to eliminate or Example 3 replace oversized components. Savings from Replacing a 50-hp Blower with a 15-hp Blower Example 4 50 hp x $70/month/hp $3,500/month Evaluating Over-design of Treatment for Air 15 hp x S70/month/hp — $1,050/month Stripper Offgas Savings $2,450/month Operational Parameters 36 lbs of VOCs per day in plant influent Payoff time: Less than one year assuming a capital 0 lbs of VOCs per day in plant effluent cost of$25,000 to replace the blower. 36 lbs of VOCs per day in air stripper offgas Off.-as Treatment(Thermal Oxidizer)Parameters designed for 160 lbs of VOCs per hour Over-designed Treatment Components requires$22,000/month for natural gas requires$3,000/month for electricity Individual components of the treatment system may be Solution: Replace thermal oxidizer with an onsite over-designed with respect to the operational parameters of the system, such as pumping rate or carbon regeneration system. influent concentration. Figure 2 illustrates why some designed for over 50 lbs of VOCs per day systems may be over-designed. capital costs for implementation: $370,000 utility costs of$2,000 per month estimated annual cost savings: $276,000 per year Comparing design parameters and actual parameters for a treatment system and its components will help 13