To: Honorable Mayor and Members of Town Council
Through: David L. Corliss, Town Manager
From: Mark Marlowe, P.E., Director of Castle Rock Water
Title
Resolution Approving Change Order No. 1 to the Construction Contract Between the Town of Castle Rock and 53 Corporation, LLC, for the Fair Street Storm Sewer Project
Body
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Executive Summary
Castle Rock Water (CR Water) is seeking Town Council approval of a change order (Attachment A) to the construction contract with 53 Corporation, LLC (53 Corp.) for the Fair Street Storm Sewer Project. The Fair Street Storm Sewer Project is replacing the existing failing storm sewer in Fair Street (Attachment B). A contract with 53 Corp. was executed in September 2020 for $163,392 plus a Town-managed contingency of $6,608 for a total approved authorization of $170,000. During the construction of the project and once Fair Street was shut down, 53 Corp. encountered a large amount of buried trash. The extent of this material was unknown and it could only be estimated until it was excavated. There was a need to get the material removed quickly to keep the project on track and get the new storm sewer main installed to prevent flooding and also so the street could be reopened. Staff reviewed closely the unit rates for disposal of the trash and backfill with clean fill material. Unit rates were determined to be consistent with previous work of this type. This trash material was hauled to the landfill and replaced with clean fill material. The total change order request is $127,093 and the requested additional funding authorization is $120,485.
Notification and Outreach Efforts
CR Water sent a construction letter notice in November in advance of the construction to the impacted business owners on the west side of Wilcox. Additionally, information about this project is posted on the Town’s website.
History of Past Town Council, Boards & Commissions, or Other Discussions
The Town Manager approved the Construction Contract for the Fair Street Storm Sewer Project, and it was executed on September 30, 2020.
Discussion
The Fair Street Storm Sewer failed in the spring of 2020. CR Water staff were able to temporarily repair the damaged section of pipe, but it was determined that the existing pipe was at the end of its useful life. This project is replacing the existing corrugated metal pipe with a new reinforced concrete pipe. The project is also adding three new manholes, an outlet structure, and an asphalt patch for the emergency pipe repair.
During the construction of the new storm sewer, the contractor encountered trash in the excavated material. The material was encountered starting at the outfall into East Plum Creek and continuing to the east to the alley. The extent of this material was unknown and it could only be estimated until it was excavated. This material was not suitable for the trench backfill for the new storm sewer pipe. It could not be properly compacted and would be a known hazard for future maintenance of the asset. In addition, a piece of the old CR Water wooden waterline installed over 100 years ago was found. This item was photographed and brought to CR Water’s operations facility for potential preservation.
The volume of material that was removed and hauled to the landfill was 1,333 cubic yards. The contractor also removed 151 tires from the excavation. The tires were separated from the trash filled dirt and taken to a tire recycler. The contractor also hauled in 748 cubic yards of clean fill material to backfill the trench. The cost for the trash removal was $101,593.
The contractor also encountered unstable material near the existing water and sanitary sewer mains located in the alley. The project team was concerned that the trench may collapse when the trench box was removed. The project team decided that the best approach to protect the existing utilities was to flow fill this area with concrete. This will provide a stable material to support the existing utilities and the pavement in the alley. The cost of the flowable fill was $4,500.
CR Water staff met with Public Works staff to evaluate the required concrete road restoration that will be needed for the project in Wilcox Street. Typically, projects are allowed to replace half panels of concrete sections, but since this project is located in the downtown area, Public Works has requested full panel replacements. The additional cost for this quantity adjustment is $30,000.
The project also included a line item for a water main depression. The depth of the existing water main in the alley was unknown. The contractor potholed the water main and determined that it was not in conflict with the new storm pipe. The water main depression will be removed from the contract. The reduction to the contract is $9,000.
The total change order request is $127,093. This project was approved with a Town-managed contingency of $6,608. The resulting additional authorization request for this project is $120,485.
Budget Impact
Funding for this project is available in the approved 2021 Budget. The project will be funded from the Storm Sewer Rehabilitation Account (Account No. 212-4475-444.79-19). A budget transfer request of $120,485 has been submitted from 212-4475-444-76-37 to 212-4475-444-79-19. Staff requests that an additional $120,485 be authorized for this project. The resulting total authorization and cost for this project is $290,485.
Staff Recommendation
Staff recommends the Town Council’s approval of a change order to the construction contract between the Town of Castle Rock and 53 Corporation, LLC, for the construction of the Fair Street Storm Sewer Project for $120,485.
Proposed Motion
“I move to approve the resolution as introduced by title.”
Attachments
Attachment A: Resolution
Exhibit 1: Construction Change Order
Attachment B: Map of the Project