SITE INFORMATION AND CORRESPONDENCE

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i 715 North Hunter Work Plan Approval Page2 D. Install four 2-inch diameter groundwater monitoring wells to approximately 40 feet bsg (screened from 20 to 40 feet bsg) to define the lateral extent of the ground water contamination at the site. Soil samples will also be collected to evaluate the extent of the soil impact. COMMENTS AND CONDITIONS: 1 . EHD recommends looking into using a slot size larger than 0.020 inch for the well screen of the DPE well to maximize extraction flow. Preferably, screen sections of different slot sizes should be available on site to provide flexibility of the slot-size selection based on field data. 2. Install the DPE well by September 30, 2005, and perform the dual phase extraction pilot test by October 15, 2005. EHD recommends you or your consultant apply for the necessary encroachment, revocable, and discharge permits from all the appropriate agencies (i.e. City of Stockton Public Works, etc) as soon as possible in order to comply with the above deadlines. 3. Implement the proposed CPT boring work and install the 4 lateral monitoring wells by October 15, 2005 . Ideally, the lateral monitoring wells should be installed at the same mobility as the DPE well to minimize additional mobility cost. However, due to the high level of contamination concentration found in groundwater and vadose zone, priority should be given to the installation of the DPE well and conducting the pilot testing in order to expedite interum remediation of the contamination. 4. Implementation of the proposed work or meeting the above deadlines is not contingent on pre-approval from the California State Clean Up Fund (Clean Up Fund) for reimbursement of the work. REASONS FOR DISAPPROVAL OF THE WORKPLAN (H&S 25299.371 subd. (C) (3) .): f ' $ None re DATED August 25, 2005 BY Teffxey C.F. Wong, Sr. REHS �., c: RWQCB, Central Valley Region — James L. L. Barton, PG c: Advanced GeoEnvironmental, Inc. (AGE) — Dan Kalmbach