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Race to the Finish

Coordinating the Construction Phase of Plum Island’s Phase 3 CIP

Jared Hartwig - Hazen and Sawyer

Last Modified Jul 05, 2022

Located on a 22-acre island in Charleston Harbor, the 36-mgd Plum Island WPCP required improvements after 50 years of operation. For Phase 3 of the Capital Improvements Project at the facility, we helped Charleston Water Systems evaluate several potential delivery methods. They selected the CMAR approach based on the opportunities it offered to optimize the design related to construction sequencing, stay on schedule, and secure available funding.

This presentation will discuss the background, design, and construction of the Plum Island WPCP Phase 3 Capital Improvements project, specifically related to the collaborative effort with the contractor as part of a Construction Manager at Risk (CMAR) contract. The purpose of this presentation will be to highlight the coordination of startup for the 36 mgd facility between two (2) onsite contractors. The presentation will outline the steps taken to coordinate startup of the proposed Phase 3 facilities pending the availability of an onsite pump station being constructed under a different contract.

Following the completion of the latest Plum Island WPCP Master Plan update, improvements for the Phase 3 Capital Improvements Project were identified. These improvements were recommended to improve plant operation and provide improvements to outdated facilities. Facilities constructed as part of the Phase 3 Improvements include the following:

  • 150 mgd Preliminary Treatment Facility
  • Two (2) 110-foot Primary Clarifiers
  • Anoxic Selector with Mixed Liquor Distribution Improvements
  • One (1) Final Settling Tank
  • New Electrical Distribution and Emergency Power Generation Facility

A Construction Manager at Risk (CMAR) contract was selected as the appropriate delivery method through design and construction to maximize project value for construction sequencing, schedule and available funding. Utilizing this method provided additional flexibility to modify the design as required to meet the variable schedules of each construction project.