SITE INFORMATION AND CORRESPONDENCE FILE 2

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Page 1 of 1 Vicki McCartney [EH] From: Joseph Krohn [JKrohn@taberconsultants.com] Sent: Monday, November 14, 2011 10:57 AM To: Vicki McCartney [EH] Cc: Tom Ballard; eieng@pacbell.net Subject: Cal Tanks Status Attachments: 01 N06E140003M.png Vicki, I wanted to give you an update on the project and a schedule for submittal of documents. As you know, a new well MW-5 was installed on September 23, 2011 adjacent to the existing well MW-2 which has historically shown free product. MW-5 was screened from 17-37' bgs, and MW-2 is screened from 30-50'. The intent of the new well was to intercept the existing water table surface currently found at approximately 25' bgs and check for the presence of free product. The results of free product measurements conducted on September 26, 2011 indicated no free product in MW-5, and about a foot of product in MW-2. These results, along with the soil testing results from MW-5, indicate that we may be dealing with a submerged plume in the area of the old waste oil tank. Review of DWR water level data (attached) for well 01N06E14Q003M located in McKinley Park about 0.5 miles north of the site indicates that the water table elevation in 1990 was about -30 feet msl when the waste oil tanks were taken out of service. This elevation is about 18 feet lower than the current elevation of about-12 feet msl. A release of heavy product to the 1990 water table may have become trapped and submerged due to the rising water table. In accordance with our Corrective Action Plan Feasibility Study, a free product recovery test was to be performed on the new well MW-5. Based on the preliminary data from September 2011, no free product is encountered on the current water table surface in MW-5. In lieu of the recovery test recommended in the CAPFS, we plan on checking for free product in well MW-5 on a weekly basis for about one month to confirm either the presence or absence of free product in well MW-5. Free product will continue to be removed from MW-2 as before. In addition to the above, a slug test on MW-4 is planned per the CAPFS to provide hydraulic conductivity data needed to perform the Monitored Natural Attenuation analysis. The slug test is currently schedule,4o occur in early December. After the slug test and free product monitoring is complete, we will issue a report summarizing the findings of this work as well as the well installation work. As far as the preparation of a work plan to perform batch extraction of groundwater at MW-4, we want to evaluate the most recent groundwater analytical data from September 2011 first. Based on the February 2011 data, there was a significant order of magnitude reduction in both TPH-Gasoline and benzene in groundwater samples from MW-4. Should this trend continue, groundwater extraction may not be warranted. Please contact us if you have any questions. Joseph Krohn, PG Taber Consultants 707 365 5843 jkrohn@taberconsultants.com 11/14/2011