SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

Mr. Robert Garcia • - 4 - • 25 May 2000 migration of contaminants. MW-13 has also not contained detectable levels of contaminants since March 1997. Leprino should abandon MW-13 to minimize the potential for vertical contaminant migration. • The report recommends that monitoring well MW-15 be abandoned. We concur that MW-15 may be abandoned, as there are additional wells in the vicinity to provide adequate monitoring coverage and no constituents of concern have been detected in MW- 15 since December 1995. • HSI also recommends abandonment of MW-17 due to nondetection of BTEX and TEH (except for"low level detections attributed to laboratory error" in third and fourth quarter 1999 monitoring events). This well contained BTEX constituents in 1995 and 1996 and TEH in third and fourth quarter 1999 monitoring events slightly above the detection limits. Also, MW-17 provides downgradient monitoring of Mobil,.which is upgradient of Leprino. Therefore, it is prudent to retain monitoring of MW-17 for at least two more quarters to confirm whether recent TEH detections are "laboratory error"or an influx of TEH contaminants from Mobil, and to show at least four consecutive quarters of nondetections for BTEX. 16. In a 23 May 2000 telephone conversation with Mr. Shine, we discussed the operation of the product recovery system. Mr. Shine stated that the recovery system operates continuously, extracting groundwater and product from wells RW-4a and RW-5a. The extracted groundwater and product are fed into an oil/water separator, and the groundwater is discharged to the local wastewater treatment facility. Mr. Shine is not certain where the extracted product is stored and disposed of, or how volumes of recovered product are estimated. Leprino needs to specify where the recovered product is stored and disposal of, and provide rationale for recovered product estimates. 17. In our 23 May conversation,we also discussed product removal occurring in monitoring wells onsite. Mr. Shine explained that prior to construction activities, Leprino examined wells bi-weekly for the presence of product. If product was found in a monitoring well, Leprino installed a skimmer to recover product from the well. Monitoring and product removal (as needed) should continue on a bi-weekly basis to further product removal from groundwater. 18. Due to the continued presence of free-phase product at the site, Leprino needs to prepare an evaluation of feasible remedial alternatives to expedite removal of free-phase and dissolved contaminants from groundwater at the site. The remedial alternatives evaluation must include the items in the attached Feasibility Study/Remedial Options Evaluation Report.