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Water Treatment Plant Upgrade

Lebanon, NH

Dufresne Group planned, designed and provided construction services for a project to update the City Water Treatment Plant to accomplish the following improvements:


  • Replace chemical bulk storage tanks and install a knock-out block wall in the existing Chemical Building to allow for future replacements.

  • Replace all chemical feed lines in the existing building and in conduits between buildings.

  • Construct a new Powder Activated Carbon silo and feed system.

  • Replacement of chemical feed pumps, dry feeder control panels and drive systems

  • Replace slide gates and sluice gates

  • Replace flocculator equipment and sludge collector equipment.

  • Replace automatic filter control and surface wash valves

  • Construct a building addition to the main Control Building

  • Construct a new phosphate storage and feed room


The replacement of the influent sluice gates, the flocculators and the sludge collectors required advance planning and a specific sequence of operations to minimize impacts on the existing treatment operations.  In addition, extended shutdown of each treatment train was required to allow time for repair of the existing cast-in-place concrete tanks.  These repair and replacement operations were completed with minimal impact and no effects to water quality.

Key Features

  • Funding through the NHDES Drinking Water and Groundwater Trust Fund

  • PAC facilities located remote from the main WTP included a Human Machine Interface to allow operator remote control all facility operations.

  • Construction occurred during the COVID pandemic with a contract time extension limited to 30 days.

Jay Cairelli, Asst. Director PW
193 Dartmouth College Hwy.
Lebanon, NH 03766
Phone: 603.448.0674

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