SITE INFORMATION AND CORRESPONDENCE

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J&L Market - 2 - 5 December 2007 8125 S. EI Dorado St., FrenL amp • ' that Methyl tert-Butyl Ether (MtBE, maximum at JLM-3, 6.1 ug/L) and 1,2-dichloroethane (1,2- DCA, maximum at JLM-13, 200 ug/L) appear to be stable or declining. The Workplan proposes installation of two monitoring wells (enclosed Figure 2) to investigate and confirm grab groundwater sample results for 1,2-DCA from the July 2005 investigation, at Cone Penetrometer Testing (CPT)-1 (18 micrograms ug/L; 87 feet below ground surface, or bgs), and at CPT-3 (6.1 ug/L, 130 feet bgs). The Workplan also proposes four additional direct push borings and grab groundwater sampling near previously sampled CPT-1 , CPT -2, and CPT-3 in the permeable sand/gravel intervals between 40 and 65 feet bgs, which were identified from CPT boring logs in July 2005 but not sampled. Comments: 1) The laboratory reporting data sheets supplied in the 2Q2007 and the 3Q2007 do not state the diesel found in groundwater at JLM-13 is weathered; nor are the TPHd chromatographs provided. A review of the chromatographs is necessary to evaluate whether a new release has occurred. 2) The installation of monitoring wells, rather than additional CPT borings, is necessary for the intermediate permeable zones. Monitoring wells will provide repeatable data sampling points, and would be more cost effective with a single drill rig mobilization, in light of the fact that the Workplan also proposes two deeper wells for this phase of the investigation. 3) The investigation will need to provide groundwater flow direction and gradients from each permeable zone, which requires a minimum of three wells per zone to triangulate across each zone. Since the previous three CPT locations are located along a straight-line axis, and do not provide adequate lateral separation to determine groundwater flow directions and gradients by triangulation, additional well locations are needed. 4) In response to the request to modify the monitoring schedule, all wells that have shown at least four consecutive quarters of non-detect for all constituents may be sampled annually during the fourth quarter of each year. Offsite monitoring wells JLM-18 and JLM-19 are currently the only wells that fit the criteria listed above. When additional wells meet the criteria for annual sampling, then those wells will be added to the annual sampling schedule with prior notification, and concurrence to the rationale for the changes by, Regional Board staff. Continue to monitor water levels in all wells on a quarterly basis. Directives: By 31 December 2007, please provide the following: • Copies of the TPHd and TPHg chromatographs for: 1) JLM-13, 2) their Standards, 3) the Blanks, and 4) the Quality Assurance, from fourth quarter 2006 through the present, with the scale noted, for review by the Regional Board Chemist. • Copies of all laboratory documentation and your communications to support or deny the 2Q2007 claim for a new TPHd release.