Wastewater Treatment Plant Upgrades

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2006
The Saco Wastewater Treatment Plant underwent two separate upgrades with the goal to significantly enhance:

• Process Control
• Bio-Solids Processing
• CSO Treatment.

City staff partnered with DeLucca- Hoffman Associates to design the CSO Treatment upgrades which were was constructed by T Buck Construction located in Auburn, Maine. These improvements included:

• Increasing the west side influent line to 24 inch HDPE thus allowing additional flow into the facility,
• A flow control valve to limit flow through secondary treatment to its' designed maximum flow of 8.4 MGD,
• A CSO vortex separator to treat an additional 5.6 MGD to primary equivalence and provide disinfection
• The addition of a vortex grit system at the WWTP's headwork's facility.

This undertaking allows the facility to better treat its design flows while deverting all excess flow to primary treatment and disinfection. Included was the addition of a new grit handling building and the removal of two offline 50' clarifier that were no longer being utilized. This upgrade was a big step towards the city completing it's ultimate goal of eliminating all combined sewer overflows.

An alternative delivery approach was utilized on the second project. The city selected Woodard & Curran for the design and city staff acted as the General Contractor. This resulted in a $500,000 savings off the original cost estimate of $1.2 million dollars. The upgrade provided enhanced process control of the secondary treatment system and utilized newer technologies for dewatering. The upgrade included:

• Conversion of the existing conventional activated sludge process to BNR
• Two multi-stage centrifugal blowers,
• The addition of an aerated sludge holding tank,
• Replacement of the existing gravity belt thickener with a rotary screen thickener,
• Upgrades to the sludge blending tank,
• Replacement of a primary clarifier drive mechanism and rake arms
• A new main electrical feed and control panel.

Staff is happy with the improvements it brought including; improved to aeration efficiencies, consistent sludge cake production and odor control, while at the same time enhancing automation and decreasing staff time.

2009
The treatment facility is currently under construction of a third project to replace a structurally failed process building that currently houses sludge processing, chemical storage, electrical distribution, controls, utilities, and maintenance facilities. These failures were due to differential settling underneath the existing process building. The City is utilizing a design team of DeLucca-Hoffman Associates, Lincoln Haney Engineers, and Woodard & Curran for these upgrades. This is a phased construction that will first construct the new process building to house sludge processing, electrical distribution, controls, and utilities followed by a garage to house maintenance and chemical storage. The project is currently under construction and has a completion date of October 2010.

GOING GREEN
The City has sought out alternative energy opportunities in an effort to become energy self sufficient. Some of projects implemented include:

• Solar thermal panels feeding radiant tubing within the floor as the heat source for the grit handling building,
• 1.8 kW wind turbine to supply power to the administration building,
• Effluent thermal heat pump to heat the new process building and garage,
• Solar air panels for additional heat of the new process building, garage and administration buildings
• Solar tube lighting though out the buildings