SITE INFORMATION AND CORRESPONDENCE

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Mr. Joseph Salazar, Jr Former Busy Bee Cleaners -2 - 10/20/03 Phase 3 Groundwater Characterization Work Plan 1. In some circumstances, it is advantageous to locate monitoring wells and select screen intervals by first taking grab groundwater samples. This procedure is not being used in this case due to a number of factors including the inconsistency between previous grab samples and monitoring well results. At any rate, there remains the possibility that the information collected under Phase 3 work plan, combined with previously collected information,may not be sufficient for the purposes of preparing the RDFS. In that case,the Regional Board may require additional investigation activities. 2. Proposed aquifer test well (EX-1BB) shall be sampled during installation and quarterly thereafter for one year, at which time the need for continued monitoring can be re-evaluated. 3. Continuous cores in the saturated zone will be taken, logged and photographed during the construction of one of the deep monitoring wells and three of the shallow monitoring wells. E2C will review the shallow cores to determine the degree of correlation in lithology between the cores. If good correlation is found, additional continuous cores will not be needed. However, if there is poor lithologic correlation between cores, additional continuous cores should be taken. 4. Collection and/or chemical analysis of soil samples shall no longer be part of the proposed work. 5. Soil gas samples will not be taken from the borings associated with the seven perimeter well locations. For the interior well locations, soil gas samples will be collected and analyzed from an additional interval of 5 to 10 feet below ground surface. This data will be used qualitatively and for determining whether soil vapor extraction is needed in that area. The soil gas information to be collected under the Phase 3 Work Plan will not be in accordance with the January 28, 2003 joint LA Regional Water Quality Control Board/DTSC Advisory for Active Soil Gas Investigations. This is mainly due to the fact that compliance with the advisory would require the presence of an on-site laboratory and, in the case of the Phase 3 work plan, it is not cost-effective to have an on-site laboratory when the focus of the work is the installation of monitoring wells. It is understood that the to-be-revised RI/FS work plan should, for risk assessment purposes, include a soil gas collection element that complies with the advisory. 6. Water quality parameters including pH,temperature, conductivity,turbidity, and dissolved oxygen will be monitored during development of new wells.