SITE INFORMATION AND CORRESPONDENCE_1988-1991

Home Browse Search

ENCLOSURE PRELIMINARY SUMMARY PROBLEM S AND GAT ON (RI) REPORT RECOMMENDATIONS FOR THE REMEDIAL SUMMARY OF PROBLEMS WITH HYDROGEOLOGIC ANALYSIS AND PRESENTATIONS • Cross-sections were drawn incorrectly which reduces the reliability of the sections and conclusions drawn from the sections. The following deficiencies or errors in the construction were found with the cross- sections. • Redundant sections; some sections fold back on each other. • Discrepancies between same wells on different cross-sections. • Some well lithology as shown on cross-sections are inconsistent with the actual well log. • Cross-sections contain acute angles. • No cross-section in north-south direction off-site. • There were no horizontal scales on the sections. Vertical exaggeration cannot be determined. • Classification of sandy-clay (SC) and sometimes sandy silts with clay (ML) , as an aquifer. These type of sediments tend to be more of an aquitard to the movement of fluids rather than as an "aquifer" . The term "aquifer" in the sense which it has been used, implies a rather transmissive unit. However, the transmissivity (T) values calculated for the A and B zones are more representative of an aquitard, and not an aquifer. If the cross- sections were redrafted classifying these type of sediments as aquitards, then it may be that there are fewer significant correlatable, highly transmissive hydrostratigraphic units than is currently depicted. • No typing of the different water bearing zones. Minerals analyses have not been consistently performed from different well clusters to type the water bearing zones and to verify if the water bearing zones are indeed different. • Conceptual model which consists of four different aquifers (A, B, C, and D zones) may be wrong. My preliminary scan of the data indicated that only the D zone could consistently be differentiated based on heads and aquifer parameters. The A and B zone may be one zone or may be combined with the C zone. • Only about six hydrographs were presented in the Report. Hydrographs need to be constructed especially for the wells with the longest historical record and the well clusters within the four zones. • The water level contour maps were computer generated and apparently were not verified by hand contouring. These maps show equipotential lines with acute angles. The flow maps were constructed for November of 1984, 1985, 1987, 1988 and 1989. This does not give enough information about the seasonal changes which occur due to pumpage by the agricultural supply wells, of which is acknowledged throughout the report. November is neither at the height of the wet or dry season.