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Wastewater Treatment Facility Upgrade

Winner "Grand Concepter" Award by ACEC-ME

Wright-Pierce has represented the Sanford Sewerage District since the mid-1990’s. Initially, we assisted them in the development of a comprehensive facilities plan to address stringent water quality standards. We subsequently designed a major facility upgrade for this 3.48 mgd facility that included:

  • Upgrade of influent pumping station (11mgd; CSO abatement).
  • New influent screening and grit removal.
  • New septage receiving equipment.
  • New biological nutrient removal oxidation ditch system designed for ammonia and phosphorous removal.
  • New spiral-blade circular secondary clarifiers.
  • Upgrade of tertiary flocculation, and chemical feed processes, (polyaluminum chloride and caustic).
  • New effluent, post-aeration tank with dedicated aeration system.
  • New medium-pressure, ultraviolet disinfection system.
  • New solids handling system, including aerated sludge storage tanks, sludge feed pumps and centrifuge dewatering equipment.
  • Conversion of existing lagoons into equalization basins for discharge management.
  • Subsequent pilot testing and Phase 2 implementation advanced phosphorus reduction facilities.

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Project Highlights
  • Major plant upgrade
  • Most stringent discharge standards in Maine
  • Energy efficiency

Challenges
During the multi-year planning process, DEP performed a TMDL study and calculated extremely stringent limits for ammonia (0.5 mg/l) and total phosphorus (0.1 mg/l) to maintain a river discharge.

Solutions
Wright-Pierce provided planning, design and construction engineering services for the recommended improvements.  The bid price for the construction project was significantly below the District’s budget.