SITE INFORMATION AND CORRESPONDENCE

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S V 2 hours,to a depth of 4 feet below the surface. Add more hydrated bentonite chips as needed. Place a cement plug above the hydrated bentonite flush with the vault floor. Remove the 3 foot by 3 foot by 3 foot deep well vault and compact backfill with clean road base to 4 inches of the surface prior to resurfacing with hot asphalt. The groundwater contamination that was present from the last well sampling on May 25, 2011 is not only in MW 10, but the entire excavated pea gravel area. The hydrated bentonite would prevent any surface spills from entering the pea gravel backfill and would seal the well screen as it expands. The May 25, 2011 sample results showed the following contaminants of concern in uglL of the pea gravel backfill MW10 and surroun ing native formation wells, MW6A, MWBA and MWBB. Well ID TPHIZ Benzene Toluene EBenzene Xylenes MtBE TBA MW 10 400 2.3 <0.5 <0.5 1.3 <0.5 <5 MW6A 2600 <0.5 0.8 5.3 48 <0.5 <5 MWBA 380 1.2 <0.5 <0.5 3.7 <0.5 <5 MW 8B <50 <0.5 <0.5 <0.5 <0.5 1 2.0 <5 Also an error in describing MW 10 construction was noted in the February 6, 2012 San Joaquin County letter. There is no 12-inch diameter by 4 foot deep steel conductor casing just below the 3 foot deep traffic vault. I have attached both the construction log and bore hole logs for MW 10 along with a cross section representation showing the relationship of MW I O to the pea gravel backfilled excavation area and the native formations. LIMITATIONS The information presented in this report is based on the following: 1. The observations and data collected by field personnel. 2. The result of laboratory analyzes performed by a state certified analytical laboratory_ 3. Our understanding of the regulations of San Joaquin County, the City of Stockton and the State of California. 4. References reviewed for this report. Changes in groundwater conditions can occur due to variations in rainfall, temperature, local and regional water use and local construction practices. In addition, variations in the soil and groundwater conditions could exist beyond the points explored in this investigation. State Certified Laboratory analytical results are included in this report. This laboratory follows EPA and State of California approved procedures; however, WEGE is not responsible for errors in these laboratory results. The services performed by Western Geo-Engineers, a corporation under California Registered Geologist #3037, have been conducted in a manner consistent with the level of care and skill ordinarily exercised by members of our profession currently practicing under similar conditions in the State of California, the City of Stockton and San Joaquin County. Our work and/or supervision of remediation and/or abatement operations, active or preliminary at this site is in no way meant to imply that we are owners or operators of this site. Please note that MW 10 Destruction Addendum to January 19,2012 Site Restoration Work Plan