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2017 Wastewater Treatment Plant Improvements Change Order 1
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SUMMARY: Change order number 1 is attached in the amount of $21,785.25. The change order does not include any additional time for the contractor and the contract time overrun will be discussed with the City Council at a later date.
The explanation for the items in the change order are as follows:
Item 1. Installation of Temporary Return Activated Sludge Bypass Line
As designed and spec by GRW Engineering it was assumed that a new 18 inch valve could be installed to isolate Basin 3 & 4 prior to the Contractor (J.S. Haren) removing and disposing solids in Basin 3 & 4 for the installation of a baffle curtain wall and 8 mixers. The level of the valve installed would be approximately 7 feet deep. Sequence of completion is not possible as specified. An option to isolate Basin 4 by routing RAS to Basin 3 was considered however the valve on this line has never been used and there is risk of valve failure in opening and closing this valve which is approximated 12 feet deep and near the wall at Basin 3. There would be serious concerns if the valve had to be excavated regarding the risk of structure failure due to location. Working with J.S. Haren an alternative would be to install a temporary RAS bypass line so that Basin 3&4 can be isolated and the upgrade move forward. This item includes labor and materials in an additional amount of $11,656.00 as summited by J.S Haren.
Item 2. Relocate mixer control panels to end of aeration Basin to improve walkway access.
As designed and spec by GRW Engineering the 4 duel mixer control panels cannot be installed by the drawing due to the size of the control panels. The control panel doors could not be opened enough for access without modification. The best alternative is to relocate the control panels to the end wall of Basin 3 which requires addition conduit, electrical wiring, and disconnects on the walkway. This item includes labor and materials in an ad...
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