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(YVATCo �- A S S O C I A T E S I N C Placement of Borings and Wells A total of three soil borings will be located in a triangular pattern in the vicinity of the "closed" or former underground storage tanks (USTs) to evaluate determine the lateral extent of petroleum affected soil and groundwater. One of these borings will be located in the inferred hydraulic upgradient (westerly) direction and completed as a groundwater monitoring well within 10 feet of the former USTs. The two remaining soil borings will be placed approximately 40 feet south and 25 feet east from the former USTs, respectively. The proposed eastern (inferred downgradient) monitoring well will be placed between the former USTs and the on-site supply well. Proposed monitoring well locations are shown on Figure 2. It is anticipated that the proposed drilling activities will generate approximately 4 cubic yards of soil and site conditions are such that available open space is limited to store the soil. Additionally, there are currently 8 drums of soil (approximately 2.2 cubic yards) stored on site from the previous June 1998 drilling activities. Immediately upon completion of the proposed drilling activities, all soil cuttings generated to date will be transported off-site to a Class II landfill for proper disposal, pending State Water Resources Board, Underground Storage Tank Cleanup Fund (Fund) pre-approval. Groundwater Monitoring Well Construction Details The three soil borings will be completed as groundwater monitoring wells. The monitoring wells will be constructed of 2-inch inside diameter schedule 40 PVC well screen and casing. A 0.020- inch well screen slot and #2/12 mesh sand pack will be used. Neat cement will be used to seal the wells in accordance with California Well Standards (December 1981). To protect the integrity of the wells, locking, water-tight well plugs will be installed on each well and a water-tight wellhead labeled "monitoring well" will be concreted over each well. Proposed well construction details are shown on Figure 3. The top of casing of the new wellheads will be surveyed to assess groundwater gradient and flow direction. Sample Analysis Selected soil samples will be immediately placed on ice and delivered under chain-of-custody documentation to a State-certified laboratory for analysis. Samples will be analyzed for total petroleum hydrocarbons as gasoline (TPHg, EPA Method 8015), benzene, toluene, ethylbenzene, and xylenes (BTEX, EPA Method 8020), and oxygenate fuel additives (EPA Method 8260). w:\14885\reports\wkpin.doe 3