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I Groundwater Monitoring Well Installation Groundwater monitoring wells associated with the subject site (Figure 3) are screened in three zones. MWl , MW2, MW3, MW8, MW9, MW10, and MW11R are screened from approximately 45 to 68 feet bgs in the shallow groundwater zone. MW4, MW5, MW6, and MW12 are screened from approximately 85 to 90 feet bgs in the intermediate zone. MW7 is screened from approximately 116 to 121 feet bgs. Based on recent subsurface investigation activities conducted at the site, the shallow groundwater plume appears to be adequately defined to the west and north in the vicinities of MW10 and MW 11R, but is not defined to the east and south. The intermediate groundwater plume appears to be generally defined to the northwest in the vicinities of MW12 and MW4, but not well defined in other directions. Groundwater flow in the shallow zone in March and June of 2005 was variable with eastward and northward components flowing toward the center of the site. Groundwater flow in the intermediate zone in March and June of 2005 was towards the south. In order to further evaluate the lateral extent of the shallow groundwater plume, one on-site monitoring well will be installed in the northeastern portion of the site and one monitoring well will be installed off-site on the adjacent property to the east. ATC proposes to pursue access to selected existing off-site wells associated with the former Apache Plastics facility. Cooperative efforts from ATC, the former Apache Plastics facility owner, and the environmental consultant for the former Apache Plastics facility (Stratus Environmental, Inc .) should result in improved understanding of subsurface conditions for both sites and reduce redundant expenses and investigation efforts. Existing groundwater monitoring wells associated with the former Apache Plastics facility are screened in similar depth intervals as the wells associated with the subject site, and are well positioned to help define the extent of groundwater contamination. According to Stratus ' quarterly groundwater monitoring report for the second quarter of 2005, the shallow groundwater flow direction has consistently been toward the east and southeast except for the first quarter of 2005, when the reported flow direction was toward the east, northeast. Apache Plastics facility well MW2 (designated as A-MW2 on Figure 3) can provide groundwater quality data southeast of the subject site. The two proposed shallow 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 with approximately 15 feet of 0.020 inch slot screened PVC. The wells will be installed to a depth of approximately 60 feet below grade. 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 . The locations of the proposed monitoring wells and existing Apache Plastics facility well MW2 are shown on Figure 3 . In order to further evaluate the lateral extent of the intermediate groundwater plume, ATC proposes to utilize off-site Apache Plastics wells MW8, MW9, and MW l l (designated A-MW8, A-MW9, and A- SAEnvironmental\28349\wkp.doe 3 ATC Associates Inc.