The Wells Sanitary District provides treatment for up to 2.0 million gallons per day of sanitary wastewater for the Town of Wells, Maine. The original wastewater treatment facility was constructed in the late 1970's. Over the years, the plant had suffered significant corrosion, and had areas that were not in compliance with the latest safety codes. In addition, a number of original equipment systems were worn out and the facility had faced some difficulties in consistently meeting a number of requirements contained in its wastewater discharge permits from the US Environmental Protection Agency and the Maine Department of Environmental Protection. As a result, by the end of the 1990's, the facility was in need of upgrade work.

To address these issues, the District selected Wright-Pierce to recommend short-term measures that could be undertaken to improve facility operations and compliance, while concurrently performing a comprehensive evaluation of the entire facility focusing on longer-term solutions.

Based on the results of the evaluation, Wright-Pierce completed the design of a major plant upgrade in early 1999. Construction of the upgrade was completed in January of 2002.

The upgrades to the facility feature:

New Preliminary Treatment
     -New two-story Headworks Building including state-of­the-art fine 
       screening unit.
     -New HEADWORKS BUILDING vortex grit removal chamber. water    
       regenerated granular activated carbon odor control unit.

Enhanced Biological Treatment
      -New fine bubble aeration sys­tem with new multiple sized blower units.   
      -Advanced design allows for SO percent increase in BOD. removal with  
        same horse­power requirements as pre­vious system.
      -With enhanced system, over­all plant power usage has been markedly
        reduced.

Solids Handling Improvements
      -New facilities for receiving, storing. and handling ferric chloride and lime.
      -New sludge press feed system. controls, and high-tech sludge pumps.
      -New innovative acid wash system to facilitate cleaning of dewatering
        equipment.

Disinfection
      -Retrofitted previously abandoned secondary clarifiers for use as chlorine 
        contact tanks and effluent pump wetwell.
      -Use of existing infrastructure dramatically lowered construction costs

Process Control and Instrumentation System
      -New SCADA system allows all equipment to be monitored and controlled.
      -SCADA system allows for trending screens, DO levels and adjustment of
       automatic control loops to improve operations.

New Aeration Blowers
        -Electrical Facilities Improvements
      -New transformer and upgrade to emergency generation system.
      -New separate electrical rooms to minimize corrosion

In summary. the upgrade was successful in improving process systems and overall facility operations. addressing worker health and safety needs. and increasing energy efficiency. The upgrade will allow the District to continue to provide reliable and environmentally sound wastewater treatment for the next twenty years.

Wells Sanitary District
P.O. Box 428
Wells, Maine 04090
(207) 646-5906
FAX (207) 646-4020

Website: www.wellssanitarydistrict.com
E-mail:  wsd@wellssanitarydistrict.com

The District's normal business hours are 8:00 a.m. to 4:30 p.m. Monday through Friday. Other hours are available by appointments made through the Superintendent's office.