R97-146 ACCEPTING THE PROPOSAL AND AUTHORIZING AN AGREEMENT

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Mr. Stephen P. Swanson August 28, 1997 Page 4 Water samples will be collected periodically during the step drawdown test and field tested for iron. Field samples from near the start and near the end of test on each well will be sent to a laboratory for analysis. This data will be used to determine the time related variation in iron concentrations in the well to determine if the pumping schedule of the constant rate test must be modified to meet the discharge pernut requirements. Additional samples can be submitted for laboratory analysis of additional parameters at your direction for the additional cost of the analysis. At the completion of the step test, we will prepare a brief letter report that summarizes the condition of the well and pump. We will make recommendations of the permanent or temporary repairs that are required to complete this project and bring the wellfields into reliable and efficient operational conditions. Additional wells can be tested at additional cost at your direction. Task 3)Measure Aquifer Parameters After the condition of the wells have been assessed, we propose to conduct three constant rate pumping tests to determine the transmissivity, storage coefficient and boundary conditions of the aquifer and the vertical hydraulic conductivity of the confining layer between the Mahomet Sand aquifer and the overlying Glasford Sand aquifer. We believe that a single well constant rate pumping test will provide a more accurate measurement of aquifer properties than can be obtained by the extended multiple pumping well test suggested in the RFP. We propose to conduct one pumping tests on wells in the DeWitt County wellfield. The pumping well will be selected on the basis of the well capacity, water quality, and position in the well field as deternuned in Task 2. At this point, we anticipate running tests on well 6, 7, 9 or 10 in the DeWitt County wellfield. The tests will be conducted for seven days at ', the highest practical pumping rate with a minimum two day recovery period. Additional ' five day constant rate pumping tests on different wells can be conducted at additional cost at your direction. The City already has an extensive network of monitoring wells in the Mahomet Sand ' aquifer. We will make as much use of these wells as possible during the pumping test. In I addition to these wells, we will install three additional observations wells, two in the I Glasford Sand aquifer and one in the clay confining unit between the aquifers. Water ',, levels will be measured in the wells for; one day prior to the start of the test, during the ' test, and for two days following the test. Water levels in the existing monitoring wells will �� be measured using the chart recorders already in place. For the DeWitt County wellfield tests, water levels in at least four of the non-pumping municipal wells will be measured i using down hole pressure transducers with digital data loggers(Hermits). Water levels in �