ARCHIVED REPORTS_FOURTH QUARTER AND ANNUAL 2010 SITE STATUS, REMEDIAL SUMMARY, AND GROUNDWATER MONITORING REPORT

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Stantec L & M OPERABLE UNIT- FOURTH QUARTER AND ANNUAL 2010 SITE STATUS, REMEDIAL SUMMARY, AND GROUNDWATER MONITORING REPORT Introduction January 31, 2011 In March 2009, Wallace Kuhl Associates (WKA), on behalf of the SRDA, concluded excavation, installation of exploratory borings, and UST removal activities on the property adjacent to the Waterfront Towers Parking Facility to the north and west. Wallace Kuhl and Associates submitted their report of findings entitled Stockton Promenade Underground Storage Tank Removal Report-Former North Edison Street to the RWQCB-CVR on June 8, 2009. In early 2010, T&R, on behalf of the SRDA, abandoned Morton Operable Unit wells MW-06R and 2BMW-1 due to the development of the DMV on the Morton-Alco Operable Unit southeast of the L&M OU. The DMV was completed and has been in operation since November 17, 2010. 1.3 REGIONAL GEOLOGY/HYDROGEOLOGY The shallow groundwater bearing zone (A-Zone) primarily extends from the ground surface to depths ranging from approximately 25 ft bgs to 40 ft bgs. Subsurface material in the shallow zone predominantly consists of silts, silty sands, and silty gravels from four to 10 ft bgs, and then organic clays, clays, high permeability silts, and lenses of silty sands and poorly graded sands to depths ranging from 25 to 40 ft bgs. The shallow zone is generally underlain by low permeability silts and clays (with an occasional, thin, silty sand or poorly graded sand lens) of highly variable thickness. A deeper groundwater bearing zone (B-Zone) is encountered at a depth of approximately 42 ft bgs and extends to approximately 50 ft bgs. Subsurface material in the B-zone consists of poorly graded sands and silty sands. Below 50 ft bgs, clay and silt with some imbedded sand is encountered and extends to a depth of approximately 64 ft bgs, underlain by sands and silty sands of varying moisture extending to a depth of approximately 73 ft bgs. Clay is encountered below the sands to an approximate depth of 84 ft bgs, underlain by a sand/silty sand layer extending to approximately 92 ft bgs. This stratum is a water-bearing zone identified as the C-Zone. Below this sand layer, imbedded clays and silts are encountered to a depth of approximately 115 ft bgs, underlain by a sand/silty sand layer with some imbedded clay to a depth of approximately 130 ft bgs. This stratum is designated as the D-Zone. Clay and silt is encountered below this sand layer to a total depth explored of 140 ft bgs. Groundwater beneath the Site is influenced by the Stockton Channel to the north and the Mormon Slough to the south. The regional groundwater flow direction for the shallow and deeper groundwater bearing zones is generally to the east-northeast. I:\Tidewater\TW Stockton(Parcel 2A-0415)\Reports\QMR\2010\4010-Annual\4Q10 and Annual OSSRQRSRQMR Stockton_FINAL.doc 1.9