SITE INFORMATION AND CORRESPONDENCE FILE 1

Home Browse Search

Circle K Store #1205 page 2 16470 Cambridge St, Lathrop. EHD will require the closest irrigation well, located at Lathrop Grammar School 1,584 feet northeast of the site, to be sampled and analyzed for the same petroleum constituents being analyzed for in the samples from the monitoring wells on site. You are hereby directed to contact the owner of the well and gain access for sampling the groundwater from it. The sample should be collected at the end of the period the well has been operating to ensure that any pumping influence this well may have on the shallow groundwater will be represented. If this well is impacted with petroleum constituents, you are to take actions to also obtain access to the next, further out, irrigation well, and have the sample from it analyzed for petroleum. The extent of influence from these large pumping wells should be evaluated with respect to the offsite migration of the petroleum plume as soon as possible. Developing effective corrective actions for the site depend on a thorough understanding of the influence effecting plume migration. If the petroleum plume has migrated to these irrigation wells, you are to immediately evaluate an interim remedial action that will effectively control the offsite migration. The interim plan should be submitted to EHD as soon as the need is determined and the action evaluated. On March 7, 2002, EHD approved the work plan to install MW-10 thru MW-15. Conditions of the approval included a requirement to analyze "a representative groundwater sample for Total Lead by EPA 6010 and Methanol by EPA 8015m". The report of the monitoring well installation and groundwater data did not include this required data. You are hereby directed to additionally sample and analyze a groundwater sample from each monitoring well associated with this site for Total Lead by EPA "LUFT" method and Methanol by EPA 8015m at the next quarterly monitoring and sampling event. When the lateral and vertical extents of the petroleum constituents associated with this site have been defined, you should present the report of findings to EHD in the context of a site conceptual model. Conclusions for delineation of petroleum in the groundwater should be supported by laboratory data at approved detection limits and QA/QC. The Corrective Action Plan (CAP) that includes a Feasibility Study should be submitted to EHD that evaluates at least two remedial alternatives that could return the groundwater to 'pre-release' conditions. The CAP should include the 'chosen' alternative that your consultant has determined to be the most cost- effective and feasible for site-specific conditions.