SITE INFORMATION AND CORRESPONDENCE_1988-1991

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Antonia Vorster -3- 25 August 1989 Hunter/ESE even by reference. In fact, two proposed well locations, 12 (a three well cluster) and 15 (an A-zone well ) , are not even shown on the Work Plan maps. Proposed well locations should be shown and discussed in relation to existing wells, sources, gradients, and plume extents. Well should also be located using definite coordinates and accurate, surveyed maps. A single base map must be selected, preferably the one used by the agencies for plume analysis, and used for all RI work. The proper approach for data correlation, integration, and presentation was carefully detailed in our 27 January 1988 memorandum. These are basic requirements for an adequate RI . That Hunter/ESE has yet to accomplish these basics makes me question their ability to adequately conduct the RI . 2. The following comments regarding data needs for individual plumes are essentially a reiteration of the comments contained in the 17 January 1989 Agencies' comments. Some of the following comments are a result of the shortcomings discussed in #1 above. For example, if accurate locations of wells were known, some of the issues may no longer be applicable. My comments, segregated by plumes as identified in our 17 January 1989 memo, are: a. South Balloon - the need for further definition in the A and B zones is dependent upon remediation; no further definition is required as long as soil hotspots to the south and north are completely captured by a final extraction system. On this basis, the A-zone is presently defined by wells 431, 404, and 440 on the south; by 428, A-1 , and A-4 on the north; and 440, 415 and 445 downgradient (downgradient extent is dependent upon agricultural well influences, however) . The B-zone is defined by the same limits as in the A-zone except the downgradient extent is again dependent upon agricultural well influences. Proper analysis of water level data is necessary to determine agricultural well influences, or lack thereof. Definition of the C-zone is not complete either to the southwest or northwest. The southwest extent can be considered coincident with the A and B-zones unless additional monitoring wells are installed to show otherwise. Proposed well locations 2C and 3C are apparently intended to define the northwest extent of the plume, but do not appear to be optimally located considering their close proximity to one another, being upgradient (south) of the soil gas hotspots near AW and AO-40 (consider contaminant levels in A-3 and A-1) , and possible agricultural well influences. Additionally, as in the A and B-zones, the downgradient extent is dependent upon agricultural influences. Such influence is most evident in the C-zone (and possibly the D-zone but no data exists) as discussed in comments regarding the Monthly Capture Zone Maps (below in this memo and in EPA' s comments) submitted by USATHMA. Definition in the D-zone is essentially nonexistent. Only two D-zone wells, 401 and 402, exist in the South Balloon. Although 402 has been nondetect for VOC's, it is at the upgradient end of the source area.