COMPLIANCE INFO_FILE 2 - Laserfiche WebLink

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Gary A. Reents 5 14 April 1989 constructed adjacent to the well cluster 7A and 7B. This well is appropriate and will provide a vertical profile of contamination at this one location. However, it is recommended that another deep well be installed in the area containing the highest shallow zone levels of TDS. This would be within the 4000 mg/1 contour shown on Figure 6. 1. 1c, near the old leach field and northwest of the waste ponds. If this well , or any monitoring well, is installed within an area of soil contamination, then the design and construction of the well should preclude the contamination of that well from drill cuttings. In many instances a double cased well has proven successful in preventing cross- contamination. If it becomes necessary to install a well within a contaminated area, a detail of the proposed monitoring well design should be submitted for review. The report also includes a discussion on the off-site domestic and irrigation well sampling program. The conclusion was that the contaminant plume beneath Southwest Hide has not impacted current off- site beneficial uses of the aquifer. This was based on the fact that all off-site wells were below the California secondary drinking water standards of 250 mg/l for chlorides and 500 to 1000 mg/l for TDS and that the shallow wells (10, 12 and 14) across the freeway from the site create a line of wells with an average chloride concentration of 12 mg/l. This discussion on the current impact of the beneficial uses of the aquifer should be elaborated upon within the Beneficial Use Analysis and Ground Water Remedial Action Plan required in the Cleanup and Abatement Order and scheduled for submittal by 1 August 1989 . In order to demonstrate that the contaminant plume is not currently impacting off site wells, the complete delineation of the contaminant plume is necessary, both horizontally and vertically. Furthermore, in order to ensure that the future migration of the contaminant plume does not impact current and future uses of the aquifer, contaminant migration rates must be determined. It is recommended that the County be contacted regarding the future uses of the ground water in this area;• Section 8 of the report states that the two old production wells on the Southwest Hide property should be investigated to determine if they are acting as conduits to deeper zones. Southwest Hide should submit a work plan on how these old production wells will be investigated. PROPOSED WORK Section 9 of the report describes the future work to be done at this site. The above comments and recommendations on the installation of the new monitoring wells, the evaluation of the integrity of the hide processing water system, the investigation of the old production wells, and the delineation of potential locations of soil contamination, should all be addressed. A brief summary of the required information and their time lines follow: