ARCHIVED REPORTS_1995 - Laserfiche WebLink

Home Browse Search

VOCs. In its March 23, 1992, letter to the RWQCB, the County proposed that well MW-5 be sampled quarterly for VOCs. Quarterly VOC sampling at well MW-5 has been conducted since the first quarter of 1992. The RWQCB has been updated on the results of the program with each quarterly report. In June 1992,consistent with the newly promulgated version of Article 5 of Title 22 of the CCR (Article 5), the County submitted to the RWQCB the report entitled the Financial Assurance Provisions and Article 5 Monitoring Program, Corral Hollow Sanitary Landfill (EMCON, June 1992). The report provided a discussion of the impact observed at well MW-5. It was discussed that Freon 11 and PCE had been detected in well MW-5 during the last monitoring events previous to the report (December 1991, February 1992, and March 1992), and that dichlorodifluoromethane (Freon 12) and methylene chloride were detected during the March 1992 event. The Article 5 Monitoring Program (EMCON, 1992) recommended that for continued groundwater evaluation at the site, a trend analysis method be used to monitor increasing concentration trends in groundwater from well MW-5. The Mann-Kendall test for trend was proposed for the site monitoring program to evaluate the correlation between time and monitoring parameter concentrations. Consistent with the use of trend analysis, the report proposed that the concentration limits for the organic monitoring parameters in well MW-5 be "no statistically significant upward trend." It was also proposed that if the primary MCLS were exceeded, an investigation of the horizontal and vertical extent of contamination may be implemented. In response to a November 2, 1992,letter from the RWQCB to the County concerning the detection of VOCs in MW-5 at Corral Hollow Landfill, an Evaluation Monitoring Program (EMP) was prepared by EMCON. It was submitted in January 1993 to the RWQCB on behalf of the County. The EMP proposed monitoring MW-5 for VOCs by EPA Method 601 on a quarterly basis, as opposed to annually, as specified in the WDR Order No. 89-046. The EMP also proposed adding SB-1 to the monitoring program for the parameters listed in the WDR plus VOCs by EPA 601 on a quarterly basis. Since the EMP was submitted, Part 258 of Title 40 of the Code of Federal Regulations (CFR), Subtitle D, was implemented into California regulations. The RWQCB issued WDR Order No. 93-200 to incorporate Subtitle D requirements into the existing state regulations. As part of the new General Order No. 93-200, a Water Quality Protection Standard Report (WQPS Report) for Corral Hollow Sanitary Landfill was prepared and submitted to the RWQCB in December 1993 by EMCON on behalf of the County. The WQPS Report reiterated many aspects of the previously submitted Article 5 Monitoring Program (EMCON, 1992), as well as incorporated the new requirements specified in the General Order WDR 93-200. SAC\N-\PJ0039M390031.9BG-94\sdg:l Rev.0,420/95 0939-003.19 2-6