Topic:
Consider and take action on a resolution authorizing an amendment to the reimbursement agreement with ExxonMobil Pipeline Company, LLC. for the relocation of the existing 6” ExxonMobil Pipeline as part of the North Extension of Landing Blvd Project (ST1914) in the amount of $719,747.38 (Executive Director of Capital Projects)
Background:
Approval of this item will authorize an amendment to the Reimbursement Agreement with ExxonMobil Pipeline Company, LLC. for the relocation of the existing 6” ExxonMobil Pipeline as part of the North Extension of Landing Blvd Project (ST1914) in the amount of $719,747.38. The increase in cost is due to a change in construction scope. The previously approved estimate assumed a conventional dig method for the installation of the new pipeline. However, after further design and coordination with adjacent pipeline companies, ExxonMobil Pipeline Company has determined that due to location, depth, and constructability issues, the new pipeline should be installed using a Horizontal Directional Drilling method. However, the HDD method requires installation of a much longer length of pipe to accomplish the relocation. Utilizing this method will provide deeper cover over the new pipeline, faster installation time and greater safety during construction. By eliminating 15-foot-deep open-cut trenches, it is estimated that the safety concerns can be mitigated by 80-90%.
This relocation is necessary due to two conflicts with the 6” pipeline. The first conflict is the likely exposure of the pipeline during the excavation for the ground improvements for the retaining wall leading up to the bridge crossing at Clear Creek. Per the retaining wall design, the excavation will be 5 feet of removal and replacement with cement-stabilized backfill. The second conflict is in Webster city limits on the NASA 1 Extension segment of the project. The storm sewer box culvert is proposed at the same depth as the 6” pipeline. The proposed res...
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