COMPLIANCE INFO_FILE 2 - Laserfiche WebLink

Home Browse Search

the highest shallow zone levels of T.D.S. ; although a deep well may be necessary to complete the site assessment, we feel that construction of the well at this time would be premature. We recommend that the proposed deep well , #7B, be installed first to obtain more information about the aquifer and vertical extent of the plume prior to committing to installation of additional deep wells. MEC feels that well #7B, planned to be installed to a depth of approximately 140' , with its proximity to #7 and #7A, would provide valuable information about the vertical continuity of the aquifer, while also depicting the vertical characteristics of the plume within a relatively highly concentrated area. The information obtained from the installation of well #7B will provide data necessary to determine the need and proper design for additional deep wells. Pump Test Work Plan Because uncertainty exists with regards to the details of the aquifer characteristics under the Southwest Hide property, MEC feels that it would be advantageous to first perform a slug test on several of the existing wells prior to designing a full scale pump test. The slug test should provide more information about the upper aquifer and enable MEC staff to better determine the method of pump test best suited for the Southwest Hide stratigraphic conditions. The additional information is desired in hopes that MEC might be able to utilize existing wells for both pumping and observation wells during the pump test. Also, before performing a full scale test it would be advantageous to first investigate the two old production wells so that they may be considered for use during the test. If the preliminary investigation reveals that use of existing wells is not feasible, new wells have to be designed so that depth, screening and spacing will provide the best information possible about the aquifer during the test. Another consideration of test design is the disposal method to be used for the pumped water. Due to the existence of highly permeable soil in the study area, discharge of water near the pump test will artificially recharge the aquifer and alter the results. A system must be designed to transport the excess water away from the test area. If the test is completed in an area of contamination, this excess water must be contained and treated or disposed of in a method consistent with state and local regulations. Furthermore, the test design must consider the potential of disturbing the existing plume. A considerable amount of caution must be exercised during the design stage of this test. Preliminary slug tests are scheduled for the week of May 22-26, 1989 and a full scale pump test is tentatively scheduled for early June 1989. 4 of 4