The Kittery Water District’s (District) 1960 Conventional Water Treatment Plant had aging process equipment with a potential for failure of critical systems. The 5 million gallon per day (MGD) facility is a vital piece of infrastructure, supplying the Portsmouth Naval Shipyard.

The facility uses a conventional treatment process with gravity sedimentation basins and automatic backwash filtration (ABW). Because the District has always prioritized removal of total organic carbon (TOC), Ballasted Microsand and Dissolved Air Flotation (DAF) clarification technologies were piloted. Piloting showed that this conventional plant, although old, performed as well as newer technologies and the District decided to retain the current treatment technology and modernize the process equipment within the plant. The project included replacement of the automatic backwash traveling bridge systems, filter porous plate underdrain, sand filtration media, flocculator wetted components, mud valves within the filter channels, and refurbishment of sedimentation basin components (see featured photo above).

The District identified additional beneficial facility improvements during the project. These included the complete replacement of filter underdrains, new control and instrumentation with SCADA upgrades, a variable frequency drive with an inverter-duty rated motor for one of its three finished water pumps, new flocculator motors and gearboxes, replacement of a deteriorated entry/loading dock, and replacement of the lime metering pumps with associated discharge and flush piping.

Future upgrade phases may include clearwell rehabilitation and replacement of clearwell interconnection and drain valves, which would require shutdown of the treatment facility for several months. Wright-Pierce studied water transfer and infrastructure upgrades recommended to supply water from York and Kennebunk-Kennebunkport-Wells Water Districts to facilitate future plant upgrade phases and improve emergency interconnections.

Water Superintendent Michael Rogers commented, “Upgrading an actively operating water treatment plant was a challenge. Carefully designed phasing of work elements and extending the contract through high-water demand periods allowed the upgrades to be successfully accomplished without disruption to our customers. Now we have a modern plant, effectively upgraded re-using as much of our existing infrastructure as we could.”

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