Regional Water System
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Wylie Water Treatment Plant Conversion to Biologically Active Filtration; Project No. 101-0390-15; Change Order No. 11
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SUBJECT
recommendation
Authorize funding in the amount of $704,669 to RAVA Construction, LLC for Change Order No. 11for replacement of Clearwell 3-2 damaged stop-logs weir wall.
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PURPOSE
During initial startup and testing of a newly constructed weir wall, the wall experienced a partial structural failure. Subsequent structural analysis determined the wall design required major modifications or replacement of the wall to function over full operating range of the system. The District staff and Engineer determined that replacement of the existing stop-log design in favor of a cast-in place wall provided the best long-term solution to maintain proper flow metering of the Wylie WTP III’s effluent for chemical flow pacing and completion of the project.
RECOMMENDATION
The Executive Director, NTMWD staff, and Carollo Engineers, Inc. recommend the Board of Directors authorize a construction change order as follows:
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Contractor: |
RAVA Construction, LLC |
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Scope: |
Construction Change Order No.11 |
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Project: |
101-0390-15, Wylie Water Treatment Plant Conversion to Biologically Active Filtration |
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Amount: |
$704,669 |
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Committee: |
This will be an item on the November 18, 2026, Water Committee meeting agenda. |
DRIVER(S) FOR THIS PROJECT
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Strategic Objective: |
1.1. High-Quality Services |
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☒ Regulatory Compliance |
☐ Asset Condition |
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☐ Capacity |
☒ Redundancy/Resiliency |
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☐ Relocation or External Requests |
☐ Operational Efficiency |
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☐ Safety |
☐ Administrative |
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☐ Policy |
☐ Other _____________ |
BACKGROUND
PROJECT PURPOSE
• Improve finished water quality by enhancing the removal of organics and thereby producing water less prone to residual disinfection depletion.
• Moderate the flow rate variability through the filters to maintain particulate capture and protect against flow-related turbidity volatility.
• Accomplish miscellaneous upgrades to support chemical addition, contact time, polishing capabilities, and in-plant water quality monitoring and control that is critical to effective initial BAF operations.
PROJECT COMPONENTS
• Filter control modification at WTP’s II and III involving programmable logic controller (PLC) based filter automation and valve controller improvements.
• Major piping relocations and interconnections to accommodate revised flow paths. Major piping includes pipe upsizing and installation of a large flow meter and vault.
• Installation of chemical injection points and associated piping and trenches.
PROPOSED CHANGE ORDER
• This change order will replace a failed project element with a more robust design. Original baffle wall design was solely structural steel. Replacement will be a cast-in place concrete wall which is a longer term and more durable solution.
• Carollo Engineers, Inc. and IMEG have agreed to contribute $376,000 toward the cost of this improvement.
CHANGE ORDER NO. 11
Description Amount Days
Original Contract $22,375,000.00 750
Prior Change Order(s) Total $420,561.56 0
Proposed Change Order No. 11
Weir wall replacement $704,669.00 150
Proposed Change Order No. 11 Amounts $704,669.00 0
Revised Contract Amount $23,500,230.56 900
FUNDING
Funding in the amount of $704,669 to RAVA Construction, LLC is to be made available via a $376,000 participation from Carollo Engineers, Inc and IMEG and $328,669 from the Regional Water System Construction Funds.