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Program Coordinator Unit IV <br />Cc: SWRCB-Cleanup Fund <br />CVRWQCB-James Barton <br />AGE-Bill Little <br />A"..........) <br />Harlin Knoll, Senior REHS <br />LOP/Site Mitigation Unit IV <br />Margarettagorio, REHS <br />3032 East Waterloo Road <br />Page 2 <br />EHD has received the Interim Remediation Addendum and Site Assessment dated 25 <br />January prepared by AGE. EHD has completed review of the 15 January 2007 and the 25 <br />January 2007 proposals by AGE and has the following comments: <br />Approved is the installation of the 4 shallow groundwater extraction wells on-site to <br />extend the plume capture zone; <br />Approved is the installation of 11 off-site MWs to define the western edge of the <br />plume in 3 distinct water bearing units identified during previous investigations and <br />on-site CMT data; <br />Approved is the installation of 4 twin CPTs to approximately 175 feet below ground <br />surface (BGS). The CPTs are located west of the proposed MWs to assess <br />groundwater and to model the migration of the dissolved MTBE plume; <br />Approved are: groundwater sampling, analysis, and reporting as proposed for this <br />phase of work. The analyses of the samples are to include: TPH-gas, BTEX, MTBE, <br />and fuel additive compounds. <br />EHD has concerns with the contamination found in the water samples from MW7E screened <br />in HU6 from 180-185 feet BGS. In addition, contamination in first water (HU1/2) is not <br />defined to the southwest of the site along Waterloo Road. These concerns were discussed <br />at the 17 January 2007 meeting and are not addressed in the 25 January 2007 addendum. <br />Therefore, EHD requires installation of one additional deep MW on-site (screened in HU6) <br />and one additional shallow MW (screened in HU1/2) off-site to the southwest next to the HU4 <br />and HU5L wells proposed for placement on 3012 Waterloo Road. <br />The EHD does not approve the installation of the four proposed deep extraction wells, but <br />will reconsider the proposal if EHD is provided a technical justification for their installation. <br />Please prepare and submit an addendum that includes the 2 additional MWs, permit <br />applications, and fees by 1 June 2007 and have this phase of work complete by 1 August <br />2007. <br />After completion of the work, a report of findings with an updated Site Conceptual Model will <br />be due 15 September 2007. <br />If you have any further questions regarding this matter, contact Harlin Knoll at (209) 468- <br />3442. <br />Donna Heran, REHS, Director <br />Environmental Health Department