CC MEETING: June 20, 2023
DATE: June 12, 2023
TO: Erin Rinehart, City Manager
FROM: Jonathan Wheat, P.E., Director of Engineering
Marc Guy, Assistant City Manager
Title
Consider Authorizing The City Manager To Execute Change Order No. 1 With A&B Construction, LLC For Additional Work Related To The Crosby Road Tract Drainage Improvements Project And The Crosby At Broadway Sidewalk Project In An Amount Not To Exceed $82,779.60, Increasing The Total Project To An Amount Not To Exceed $1,331,120.60.
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BACKGROUND:
There is an existing drainage culvert south of Crosby Road under the freight railroad tracks that is severely undersized to accommodate the stormwater flow it receives. The tracks are owned by DART and used by the DG&NO Railroad. The area immediately upstream of the culvert is the Carroll Crest residential development, which is currently under construction. To develop the property, the undersized culvert had to be replaced in order to eliminate the stormwater bottleneck at the railroad tracks and associated upstream ponding.
A drainage study performed by the engineering firm TNP identified the necessary improvements to address the bottleneck conditions under the railroad tracks and the associated overtopping of the rail. The engineering firm of Pacheco Koch designed the construction plans in accordance with the findings from the drainage study and input from DART. A&B Construction was awarded the bid for the construction of the culverts and began construction of the project in the fall of 2021.
The items below need to be added to the construction contract to ensure the project is completed in a satisfactory and sustainable manner.
Change Order No. 1 addresses the following issues:
• Installation of 8” Water Valves - This item reflects a change to install additional water valves on the 8” water main that parallels the property on the west side. The water main was lowered, and the additional valves will allow the main to be shut down on either side of the lowered portion if needed.
• Lowering of the Water Line - The 8” water main which runs perpendicular to the box culverts had to be field-adjusted to ensure that enough clearance was maintained under the culverts. Approximately 70 feet of water line had to be lowered for the culvert installation.
• Headwall removal/rock riprap added for erosion control - Due to the box culvert being enlarged to accommodate the drainage for the Carroll Crest development, and that the development would likely begin construction within 12 months of the box culverts being completed, it became apparent during construction that any end treatment on the box culverts would have to be demolished and replaced to accommodate the development’s layout. It was determined that the best temporary solution was to leave the upstream end treatment off of the box culverts and accommodate for this situation with additional upstream riprap to ensure that erosive water velocities from the creek did not undermine the box culverts.
• Increased Manhole Size - An old existing manhole in the project area needs to be replaced and enlarged to meet current City standards.
FINANCIAL IMPLICATIONS:
This change order is for an amount not to exceed $82,779.60, which increases the construction contract from $1,248,341.00 to $1,331,120.60, which is a 6.63% increase. Funding for the additional amount is available in the Drainage Consolidated Fund.
IMPACT ON COMMUNITY SUSTAINABILITY:
This project will support the City Council’s strategic objectives and vision of building a community that families and businesses want to call home by:
• Serving as an enabling component for the Carroll Crest development.
• Reduce the potential of flood damage to businesses along Broadway and upstream from the railroad tracks.
• Reduce cleanup in the area after major storm events.
STAFF RECOMMENDATION/ACTION DESIRED:
Staff recommends that City Council authorize the City Manager to execute Change Order No. 1 with A&B Construction in an amount not to exceed $82,779.60, increasing the construction contract to an amount not to exceed $1,331,120.60.