SITE INFORMATION AND CORRESPONDENCE_FILE 2

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Mr. Ken Gillies Gillies Trucking 3931 Newton Road, Stockton Page 2 of Impacted groundwater in the 1St RBA is currently monitored by three monitoring wells (GT5, GT-6 and GT-9); the 2nd RBA is monitored by two monitoring wells (GT-1 and GT-3). The 3`d RBA is not monitored by any wells. UEC has proposed installation of up to 18 wells, both nested and individual, in 10 borings, to better characterize the sand bodies and impacted groundwater. Impacted groundwater in the 3`d RBA is not characterized in any direction from the initial hit in CPT-1. Proposed monitoring wells GT-12 through GT-15 appear to be a reasonable approach toward characterizing the sand body and delineation of impacted groundwater and are approved. Impacted groundwater in the 2nd RBA has been encountered in CPT-1 and has been variably present or absent in GTA, GT-2 and GT-3 immediately southeast and southwest of the former tank pit. The 2nd RBA sand appears to be thin or absent south-southeast or northwest of the inferred channel sand (CPT-3, CPT-5 and CPT-6). The extent of impacted groundwater in the 2nd RBA has not been determined toward the domestic well (G-1), or northeastward or southwestward of the former tank pit along the inferred channel axis. UEC has proposed installing monitoring wells GT-12 and GT-14 through GT-18 in the 2nd RBA to assess groundwater and to further characterize the sand bodies.. Proposed wells GT-12 and GT-15 are located near the domestic well and the former UST pit, respectively, are necessary and are approved. Proposed wells GT-14 in the 2nd RBA to some degree duplicates GT-3, but being nestled with the 3`d RBA well may provide useful information and is tentatively approved. Proposed GT-16 is along the inferred channel axis and will monitor the northeast extent of the dissolved plume and is approved. Proposed well GT-17 appears to be on the margin of the modeled 2nd RBA aquifer. The EHD approves advancing the boring and tentatively approves installation of the well if the 2nd RBA sand is present; otherwise good professional judgment should be exercised based on field evidence whether the well should be installed. Proposed well GT-18 is located along one possible channel axis, and is approved. Impacted groundwater in the 1St RBA is currently monitored by GT-5, GT-6 and GT-9; wells GT-5 and GT-9 are variably impacted or not impacted while GT-6 is generally impacted, the lateral extent of impacted groundwater requires further assessment. Proposed wells GT-13, GT-16, GT-19 and GT-20 are located along the inferred channel axis and are approved. Proposed wells GT-17 and GT-21 are located along the inferred southeast channel margin and are needed for lateral assessment of the plume and channel definition and are therefore approved. An undesignated monitoring well near the domestic well G-1 is approved as necessary to protect G-1.