R98-39 AUTHORIZING THE AMENDMENT OF AN AGREEMENT

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Layne GeoSciences� 'nCi. A Subsidiary of Layne Christensen Company 1900 Shawnee Mission Parkway•Mission Woods,Kansas 66205•913/362-9906•913/362-2359(FAX) March 9, 1998 Mr. William Ratekin Assistant City Engineer #1 Gary K. Anderson Plaza Decatur, Illinois, 62523-1196 RE: Additional Information on 30 Day Extended Pumping Test Dear Biil, Layne ('reoSciences, Inc. (LGI) is pleased to submit some additional information on the proposed 30 day extended pumping test. We recummend that six wells be pumped on a cc�ntinuous basis for 30 �iays without rotating wells or changing pumping rate. The wells will be selected by agreement between the City and Layne. This design is intended to provide the most useful aquifer data and duplicate previous pumping events to prevent new problems with private wells and unexpected problems with the well field. To address the points raised in your letter by number: 1). The daily �iast�f the 30 day test is $1,915.00 per day. This cost includes a man on site 24 hours a day (t�ree eight hour shifts), �ivzng costs for crew, support vehicles, I mobilization cosis to nnove crews in and out of the site, rental costs far up to 13 digital � data loggers, and equipment and personnel costs for monitoring a minimum of a two day recovery period after the test. Assumiiig 30 days of pumping, this amounts to a cost of $57,450.00. The remaining $39,550.00 of the $97,000.00 budget for the test includes $8,000.00 labor c�sts tu install tempor�ry flow xneasu.rement devices, installing two monitoring wells into the Glasford sand and one into the clay confining unit, and additional modeling work and repo�i preraration. 2). We will install temporary flow measurement devices to measure the discharge of the well field. The type af devices used will depend on the specific wells used for the test and the discharge piping at each well. We will use a combination of orifice plates flow meters plumbed off the pump discharge with discharge lines to the distribution collection points or temporary weirs or gauging stations along common discharge lines from multiple wells. As an option, we are willing to install permanent flow meters at each pumped well. The meters we propose to install are Micrometer MW500 ten inch meters. The specification sheets are attached. As described in our letter, we will install six meters for an additional [GI