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TC -------- 1117 Lone Palm Avenue, Suite B (YVAModesto, CA 95351 www.atcassociates.com 209-579-2221 ASSOCIATES I N C . Fax 209-579-2225 Environmental, Geotechnical and Materials Engineers groundwater plume, two off-site monitoring wells are proposed to be installed east of the former Apache Plastic facility at the Central Valley Lift Truck property. The intermediate groundwater monitoring wells are proposed to be installed east, northeast of existing Apache Plastics monitoring well MWI0 and southeast of MW6 at the locations shown on Figure 3 . The four proposed groundwater monitoring wells will be installed using a hollow stem auger equipped drilling rig. Drilling will be conducted by a State-licensed (C57) drilling company. A field geologist will be present to log drill cuttings. Descriptions of soil types encountered will be recorded on well logs. Soil samples will not be collected for laboratory analyses. The monitoring wells will be constructed of 2-inch inside diameter schedule 40 PVC well screen and casing. The two shallow groundwater monitoring wells will be installed to a depth of approximately 60 feet below grade with approximately 20 feet of 0.020 inch slot screened PVC. The two intermediate groundwater monitoring wells will be installed to a depth of approximately 90 feet below grade with approximately five feet of 0.020 inch slot screened PVC. A sand pack will be placed in the annulus of each well extending from the bottom of the well screen to approximately three feet above the top of the screen. Approximately three feet of bentonite will be placed on top of the sand pack and hydrated with potable water. The remaining annulus will be grouted to surface with cement grout. To protect the integrity of the wells, locking, watertight well plugs will be installed on each well and a watertight wellhead labeled "monitoring well" will be set in concrete over each well. Once the wells are installed, the tops of the well casings will be surveyed to sub-meter accuracy relative to a known benchmark. At least 48 hours after installation, the four new wells will be developed using surging and bailing techniques until the purged groundwater is relatively sediment free. The wells will be sampled at least 48 hours after they are developed. Prior to the collection of groundwater samples, the depth to groundwater will be measured in each well to evaluate the direction and magnitude of the groundwater gradient beneath the site and a minimum of three well volumes (casing and sand pack) of groundwater will be purged from each well. Temperature, pH, and electric conductivity will be measured and allowed to stabilize. Water samples will be collected using disposable bailers, one dedicated to each well. Sample Analyses Groundwater samples collected from the monitoring wells will be submitted under chain-of-custody procedures to a State-certified laboratory. The groundwater samples will be analyzed for gasoline ranged organics (GRO) utilizing EPA Method 8015B, and benzene, toluene, ethylbenzene, and xylenes (BTEX), methyl tertiary butyl ether (MTBE), ethyl tertiary butyl ether (ETBE) di-isopropyl ether (RIPE), tertiary amyl ether (TAME), tertiary butyl ether (TBA), 1 ,2-dichloroethane (1 ,2-DCA), and 1 ,2-dibromoethane (EDB) utilizing EPA Method 8260B . S:\Environmental\28349\wkp.doc 4 ATC Associates Inc.