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Report of investigation Former Underground Storage Tanks 3105 South El Dorado Street Stockton California Sierra-Pacific Project No 96-620 01 ' 4 2, below, and Boring Logs in Appendix B) Other soil samples were collected to document the soil and/or stratigraphic profile beneath the project site, and to estimate the relative permeability of the ' subsurface materials ' Each boring was advanced slowly to allow for identification of changes in soil types The soil boring was logged and soils described in accordance with the Unified Soil Classification System Potable tap water was available at the site for hydrating bentonite, mixing grout, and washing sampling ' tools Drilling tools were pre-cleaned using high-pressure steam by the drilling contractor Auger cuttings were placed in labeled 55-gallon drums and were staged at the subject site for disposition Drums of equipment decontamination rinsate and purge water were also staged at the site pending sample analysis Disposal of these wastes will be the responsibility of the owner, but guidance and Massistance with waste disposal arrangements will be provided by Sierra-Pacific ' 3.3 Well Construction and Development ' Monitoring well MW-2 was constricted in soil boring B-2 The monitoring well was cased with 2-inch- diameter threaded, factory-perforated and blank Schedule 40 PVC casing pipe The perforated interval in the well (30 ft to 50 ft bgs ) consists of slotted casing with 0 010-inch wide by 1 5-inch long slots, with 42 slots per foot A threaded PVC cap was secured to the bottom of the casing, no solvents or cements were used The well casing was purchased pre-cleaned, and arrived at the site still stored in its original plastic wrapping After setting the casing inside the hollow-stem auger, RMC Lonestar#2/12 filter sand was poured into the annular space between the well screen/casing pipe from the bottom of the bore hole (50 feet bgs) I to 2 feet above the top of the well screen (28 feet bgs) The sand was emplaced slowly and the filling process was checked frequently with a weighted measuring tape to prevent bridging and creation of void Sierra-Pacific Groundwater Consultants, Inc 6