Chlorine System Replacement and Scrubber Rehabilitation

Chlorine System Replacement and Scrubber Rehabilitation

Project Manager

Water Utilities Engineering  / Bill Millis, P.E.

SUA Project No. 16WG08

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What We're Doing

The City of Stillwater and the Stillwater Utilities Authority will be rehabilitating the chlorine scrubber and replacing the chlorine feed system at the Water Treatment Plant (WTP).

Anticipated Milestones

  • Anticipated Date (Design): Design began FY2018
  • Anticipated Date (Construction): TBD
  • Anticipated Date (Completion): TBD

Benefits of the Project

The chlorine system is aging and deteriorating. WTP staff currently rely on outdated instruments for measurement and control. The chlorine system replacement will include new cylinder regulators, chlorine feeders and fine-tuned measurements and control. The chlorine scrubber rehabilitation will extend the life of the scrubber.

Budget & Funding

  • Year Funded: FY2019
  • Funding Source: Water Fund
  • Project Budget: $409,601
  • Expenditures to date: $316,000

Project Management


February 7, 2017: Black and Veatch has been hired to provide conceptual design services.

March 12, 2018: After evaluation most of the process and chemical feed systems at the WTP, a priority has been assigned to each individual component. The Project Team will prepare a Facilities Plan to develop a conceptual and phasing plan for the work to include the chlorine system.

December 10, 2018: A 65% Design Workshop was held with Project Team members. The chlorine design effort was put on hold until the Facilities Plan is complete. This will minimize the number of phases needed to construct the new chlorine system.

April 15, 2019: The WTP Scrubber Replacement quote submissions were opened on March 4, 2019. Integrity Municipal Systems was awarded the work and will begin the rehabilitation effort on April 22, 2019. Rehabilitation will include a pump replacement, replacing belts and seals, and replenishing the chemical that treats the chlorine if a release were to occur.

April 22, 2019: Work on the WTP Scrubber Replacement is underway.

View of barrels stacked outside chemical building

May 10, 2019: The chlorine scrubber rehabilitation and testing is complete. This system provides protection to employees and the public during an emergency chlorine spill.

picture of the new scrubber installed outside the chemical building at the water treatment plant

August 13, 2019: The Facilities Plan is 75% complete and presents multiple options for process and chemical system locations, all of which include expanding the footprint of the chlorine feed system.

October 28, 2019: The Facilities Plan is 90% complete. The Project Team is considering phasing options while striving to minimize project costs. 

January 22, 2020: WTP maintenance staff are preparing to procure chlorine feed equipment in order to replace aging equipment that no longer has available parts. Alternative Project Delivery (APD) methods are being considered for the overall WTP needed improvements which have a combined design and construction cost estimate of up to $60 Million.

April 23, 2020: The warranty period for the scrubber rehabilitation effort has ended with no identified deficiencies. The delivery of the replacement parts for chlorine system repairs has been delayed due to the COVID-19 Pandemic. Evaluation of the overall disinfection approach is ongoing with recent pilot test results providing new insights to optional treatment strategies.

July 14, 2020: A technical memorandum comparing chlorine gas to liquid sodium hypochlorite is complete. Results suggest that changing to sodium hypochlorite for primary and secondary disinfection will prove to be beneficial to the WTP's overall process based on cost and non-cost factors. Staff is considering the recommendations and path forward.

September 28, 2020: A presentation was delivered to City Council and SUA describing various scenarios for the future of the Water Treatment Plant and the Raw Water Supply Line. The presentation included early planning level cost estimates and rankings, among other topics. Staff will move forward with solicitation of a Designer/CMAR team (CMAR: Construction Manager at Risk). 

Actions Authorized by Stillwater Utilities Authority (SUA)

  • 1.9.17  I  SUA-17-01  I  Professional Services Agreement

  • 7.17.17  I  SUA-17-22  I  Amendment to Professional Services Agreement

  • 9.10.18  I  SUA-18-34  I  Request for Additional Expenditures and to Execute Contract Amendments to the Professional Services Agreement

  • 3.11.19  I  SUA-19-08  I  Request to Award Chlorine Scrubber Construction Quotes Package.

  • 9.28.20  I  Presentation I  Stillwater Water Treatment Plant & Raw Water Supply Scenarios


Existing out-dated chemical feed system.
View of existing chemical feed system

chlorine tanks in the chemical feed building at the water plant