SITE INFORMATION AND CORRESPONDENCE

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Antonia Vorster -2- 24 May 1990 MAJOR COMMENTS 1. Much of the information required to be included in the Technical Report, as requested in our letter of 6 February 1990, was provided in the Report, and the time schedule for items 1-2, above, are acceptable. However, the Report did not meet the major objectives: a) to provide a work plan and time schedule detailing how the extent of pollution will be determined, b) to control high TDS sources. 2. The ponds were not proposed to be closed or upgraded to Subchapter 15 standards within a reasonable time period in order to control the major source of pollutants. 3. No actions are proposed to prevent further vertical pumping induced spreading of salt pollution. SMS therefore should consider providing interim ground water mitigation. DETAILED COMMENTS A: GENERAL 1. The figures used in the report were unclear. Several , as discussed below, were either of a scale to make them not legible, or had errors which made them confusing to interpret. It will be necessary to resubmit several of them after corrections are made. B: GROUND WATER 1. Monitoring wells 1, 2, 3A, and 3B all are constructed wi :.h gravel filters of excessive lengths (up to 96 feet) which effectively can draw in water from long intervals, and act as conduits for contaminant migration. All future well designs should be submitted to this office for approval prior to installation, and should have filters of appropriate lengths to draw water only from the specific interval of concern. Interpretation of data from these wells must be done very carefully, keeping in mind the potential vertical connection of aquifers. 2. Well 3B has shown TDS and chloride concentrations up to 2510 and 938 mg/L, respectively, to a depth of 220 feet, the depth of the bottom of the gravel filter. This can be compared to the maximum TDS and chloride concentrations found in well B of 360 and 22.8 mg/L, respectively, indicating significant water quality impairment at depth. The use of filler material (Schwartzgruber Birdseye) in the bottom of well 3B, from 231 to 292 feet depth at the bottom of the boring, may have provided a conduit for additional pollution of the lower aquifer. In comparison with the well log, the 11 foot bentonite plug may not have effectively sealed off the sand zones, leaving a pathway for contaminant migration. Any future well(s) should be properly grouted.