Thornton Wes Brown Water Treatment Plant Expansion

Client: Thornton, Colo.
Completion Date: 2005
Location: Thornton, Colo.

Summary

Burns & McDonnell provided design and construction administration services for the expansion of the Wes Brown (formerly Columbine) Water Treatment Plant in Thornton, Colo. The project addressed water quality concerns as a result of upstream discharges in the source water, and increased the capacity of the plant to accommodate future water demands.

The existing conventional treatment plant was nominally rated at 28 million gallons per day (MGD). This project, completed in August 2005, involved upgrading the entire plant and increasing the plant capacity to 50 MGD using advanced membrane treatment processes. As of completion, the plant is the largest immersed membrane plant in the country, and the largest membrane retrofit in the world.

This complex design involved retrofitting the existing Wes Brown Water Treatment Plant with 50 MGD of enhanced pretreatment, low-pressure ultrafiltration (UF) membranes, and ultraviolet (UV) disinfection. New chemical storage facilities, a new 3-MG clearwell, and a new 60-MGD high service pump station were also included in the design, and the existing chlorine gas disinfection facility was replaced with a new disinfection facility utilizing bulk sodium hypochlorite. The plant is designed for the future addition of 15-MGD of reverse osmosis (RO) capacity to treat a portion of the flow to reduce TDS and nitrate concentrations. In addition to providing excellent finished water quality and ease of operation and maintenance, the plant includes a secondary recovery system that provides a potential water savings of 1.7 billion gallons of water per year.

To provide the City of Thornton with the most cost-effective and reliable solution, five MF/UF membrane systems were pilot tested along with three RO membranes. The MF/UF pilot systems included three submerged vacuum systems, and two low-pressure systems. Data collected during this phase was used to evaluate performance, develop preliminary cost estimates and develop design criteria.

Our in-house engineers were responsible for all aspects of the project including pre-design evaluations, pilot testing design and evaluation, process and ancillary equipment design, preparation of bid documents, oversight of construction, and preparation of zoning and annexation applications to accommodate future needs at the plant. The retrofit was designed with innovation and constructability as key considerations to meet an extremely tight construction schedule, since the plant could only be taken out of service for six months. The fast-track project utilized a Construction Management at Risk (Modified Design-Build) approach to expedite the project and accelerate the schedule by approximately one year.  The project was completed on schedule and under budget.

Services

  • Ultrafiltration
  • Reverse osmosis
  • Advanced membrane treatment
  • Membrane pilot testing
  • Ultraviolet (UV) disinfection
  • Enhanced pretreatment
  • New clearwell
  • New chemical feed storage/feed
  • New high service pump station

Features

  • The largest immersed membrane plant in the country and the largest membrane retrofit in the world.
  • Winner of the American Council of Engineering Companies of Colorado Excellence in Engineering Award.
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