ARCHIVED REPORTS_XR0009937 - Laserfiche WebLink

Home Browse Search

' 01 November 2005 • AGE-NC Project No 02-0950 ' Page 6 of 9 ' 2 3 5 Well Head Survey On 21 September 2005, a California state-licensed surveying engineer from Morrow Surveying ' surveyed the location and elevation of monitoring wells MW-4 and MW-5, the global positioning system (GPS) location was surveyed to the nearest 0 1-foot relative to coordinate datum NAD 83 (1986), and the elevation at the notch in the top of the well casing was surveyed to the nearest 0 01- foot relative to City of Stockton Benchmark#102 The elevations of wells MW-4 and MW-5 were determined to be 7 53 feet and 7 52 feet above mean sea level (MSL), respectively The surveying report is included in Appendix E 3.0. FINDINGS ' Soil descriptions from borings B5, B6, MW-4, MW-5 and the computer-generated CPT lithologic logs were Integrated with previous subsurface soil descriptions to construct cross-sections B-B' and C-C' (Figures 3 and 4, respectively) Hydrocarbon Impact to ground water and soil was quantified by laboratory analysis of ground water and soil samples • 3 1 STRATIGRAPHY In general, silty clay and clayey slit, with lesser, discontinuous layers of sandy material, were encountered from surface grade to approximately 23 feet to 25 feet bsg From between 23 feet and ' 25 feet to approximately 29 feet bsg,silty sand and fine-to coarse-grained sand was identified, grain size appeared to Increase with depth From 29 feet to approximately 67 feet bsg,silty clay and clayey silt were encountered,with a thin,discontinous layer of sandy material encountered at approximately ' 34 feet bsg in borings MW-4 and MW-5, a thin layer of sandy sediments and stiff, fine-grained material was encountered at approximately 52 feet bsg,as well From 67 feet bsg to 76 feet bsg,silty sand and sand,underlain by silt, was Identified in boring CPT-1,with silty clay,clay,and stiff,fine- grained material encountered from 76 feet to the total depth of boring CPT-1 at 97 feet bsg Geologic cross-sections B-B' and C-C' are illustrated on Figures 3 and 4, respectively Soil boring logs are provided in Appendix B i 3 2 HYDROGEOLOGIC MODEL iBased on the soil boring and CPT results and comparison with soil descriptions from borings previously advanced on the site,AGE has developed a preliminary subsurface model of the site soil istratigraphy comprised of six informal zones - a vadose (unsaturated) zone and five hydrogeologic units Hydrogeologic units may be defined as distinctive vertical intervals of soil with a significant iAdvanced GeoEnvironmental,Inc i