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Holt Bros. <br /> Proposed Groundwater Contaminant Mitigation Measures <br /> Project No.W0402.00 <br /> Page 2 <br /> In December of 1989 Bio National Corporation installed a cycle skimmer pump and prototype <br /> biologic treatment system for operation on effluent from MW 1. The skimmer pump had limited <br /> success in free product removal due to the apparent small volume of floating free product and <br /> low pumping yields. <br /> RESNA (formerly WaterWork Corporation) was retained by Holt Bros. to continue work at the <br /> subject site. On December 19, 1990 RESNA performed quarterly groundwater monitoring and <br /> sampling. Free product was observed in well MW L Laboratory analyses detected hydrocarbon <br /> analytes and halogenated volatile organics in monitoring well MW5. Groundwater flow beneath <br /> the site was determined to be southwesterly, which is consistent with observations presented in <br /> Dames & Moore's earlier reports. <br /> On January 9, 1991 RESNA performed a short term step drawdown test and longer term (4 hr) <br /> constant rate pumping test using well MW6. The step test indicated the well does not exhibit <br /> significant well losses and is reasonably efficient. This is discussed in detail in RESNA's April <br /> 19, 1991, Progress Report/Remediation Feasibility Study for the subject site. <br /> At the request of PHS/EHD, RESNA performed quarterly monitoring and sampling on July 28, <br /> 1992. Free product was again observed in well MWI, with a thickness of less than 0.03 feet. <br /> Laboratory analyses detected hydrocarbon and halogenated volatile organic constituents in MW5. <br /> Groundwater flow beneath the site was to the southwest. <br /> PROPOSED MITIGATION MEASURES <br /> To actively remove floating free product from groundwater beneath the site, Holt Bros. will <br /> initiate free product removal from well MW 1. Due to the low volume of product and <br /> demonstrated low yields, product removal will initially consist of handbailing product from the <br /> well twice per month. Bailing will be accomplished using a disposable bailer. Recovered <br /> product will be stored in the permitted on site above ground waste oil tank pending disposal. <br /> All personnel performing product removal will be trained in accordance with OSHA standards <br /> and will utilize appropriate personal protective equipment. Product removal frequency will be <br /> evaluated as additional data regarding product volume and yields are obtained. Holt Bros. will <br /> evaluate low volume product skimmers for potential use at the site. <br /> In addition to product removal, groundwater beneath the site will be monitored periodically. <br /> Initially, this will consist of monitoring fluid levels and collecting groundwater samples from <br /> each site monitoring well on a quarterly basis. Groundwater monitoring reports will be prepared <br /> and submitted to PHS/EHD and the California Regional Water Quality Control Board, Central <br /> Valley Region (RWQCB). Reports will summarize site activities during the reporting period. <br /> Holt Bros. is currently evaluating the feasibility of active soil remediation at the site. <br /> L021093.JPL <br />