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R&B CASE # I WELL NO. 3 AND NO. 4 UPDATE By: Steve Jankowski, City Engineer Background: The purpose of this case is to discuss with the committee three proposed change orders associated with Well No. 3 and the proposed work for Well No. 4. At the present time, Well No. 3 is operable and can produce water for the utility pending a safe bacteriological sample which is expected prior to the R&B meeting. Staff is asking for approval of three modifications to the existing contract on Well No. 3. First, we are requesting authorization of a $701 contract addition to cover the cost of two concrete- filled protective bullards and a concrete pad to accommodate the electrical power transformer. It was anticipated that the electric utility would supply these as a part of their installation, but the power utility does not provide for these materials. Second, we are requesting an increase of $645.45 to accommodate a larger chlorine booster pump. The pump specified was based on an anticipated well capacity of 1,000 gallons per minute. The actual capacity is 20% higher. A third modification involves the addition of a pressure switch to serve as a control for Well No. 3. Until the SCADA system is installed in late 1997, the pressure switch will automatically control the starting and stopping of Well No. 3. After the SCADA system is installed, this pressure switch will continue to serve as automatic back-up control if for any reason the well house should lose communication with the SCADA system. The cost of the addition of the pressure switch is $4,418. As you may recall, the Council authorized the construction of Well No. 4 on May 13 and it was proposed to locate the well approximately 2,000 feet west of Well No. 3 on the comer of the Menkveld property. Mr. Dick Foster, the consulting engineer, has advised that the City may wish to have a test well drilled at this location prior to constructing the production well. Although Well No. 3 produced more than the targeted output of 1,000 gallons per minute, the thickness of the aquifer was thinner than expected. The generalized bedrock surface elevation map shows that the proposed site for Well No. 4 would be located in approximately the center of a minor bedrock valley, which suggests that the water-bearing aquifers might be still thinner than Well No. 3. A thinner aquifer would reduce the potential capacity of the well or could prohibit the use of blasting for the development of the well and consequently the production may be only in the usage of 600 to 800 gallons per minute. (Blasting was utilized to develop Well No. 3.) Mr. Foster is obtaining quotations from four well developers to perform a four-inch test well, and these should be available at the meeting. The cost is expected to be in the range of $6,000-7,000 for the test wells.