Seneca Wastewater Treatment Plant Improvements Project

MCES Project No. 807520

Understandably, the spread of COVID-19, also known as the coronavirus, has raised questions about the status of Metropolitan Council Environmental Services (MCES) plant and interceptor construction projects. Please note the following:

  • Construction on wastewater treatment plants and sewer interceptors will continue. The contractors are following working environment protocols (asking employees to stay home if they are sick, social distancing, etc.) as outlined by public health agencies.

  • Some project staff are working remotely while others remain on-site to ensure proper oversight of the project. Staff will stay connected through emails, conference calls, and web-based meetings to manage construction activities.

Contact information

For information regarding construction, please call the construction hotline or send an email to the contact information listed on the bottom of that project’s website.

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While the response to COVID-19 continues to evolve, we will continue to monitor and review construction activities and conditions through our field inspectors and their on-site reporting.

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Minnesota's response to COVID-19

The latest information on the state’s response can be found on the Minnesota Department of Health website.


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Project Update - March 2021.  See Project Updates below.

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Project Description

Metropolitan Council Environmental Services (MCES) began making several improvements in summer 2018 to its Seneca Wastewater Treatment Plant in Eagan. The plant serves the cities of Eagan, Bloomington, Burnsville, and Savage, and small portions of Lakeville, Apple Valley, Inver Grove Heights, and Edina. The plant treats approximately 22 million gallons of wastewater daily.

The improvements will preserve and renew aging equipment and facilities, increase energy efficiency, and help MCES operate the plant efficiently and cost-effectively into the future. The major components of the improvements are:

  • Upgrading the wastewater solids incineration exhaust system to meet new federal air emission limits.
  • Replacing solids thickening equipment, along with the related odor control system.
  • Replacing the roof and safety railing on the Solids Processing Building.
  • Replacing lighting, aeration equipment, boilers, and solids processing equipment to decrease energy use (estimated $200,000 annual energy savings).
  • Repairing deteriorated concrete and installing a liner in primary wastewater treatment facilities.
  • Reconfiguring a plant building for additional maintenance work areas and equipment storage.

A separate construction project involves installation of the Seneca Community Solar Garden three blocks east of the treatment plant. The solar garden will produce just under 1 megawatt of electricity – the equivalent of powering about 164 homes. Subscribers to the solar garden currently include the cities of Eagan and Burnsville, Dakota County, MCES, and Metro Transit. The solar garden will be installed on 4 acres of a 7-acre site where the Seneca Plant landfilled ash from its solids incinerator from the mid-1970s to the mid-1980s. MCES closed the landfill in 1986 and continues to do post-closure monitoring. MCES leases the land to solar facility owner Cyprus Creek Renewables. 

The Ash Landfill site presents a unique challenge to developers attempting to install solar panels without being able to make any permanent footings into the soil.  Two feet underground is a membrane covering the buried ash.  Because this membrane cannot be penetrated, all solar panels and electrical conduits must be supported above ground, including the perimeter fence.  To accomplish this, concrete platforms or “ballasts” are used as structural load-bearing platforms to support all the solar arrays, electrical conduits and fencing that are mounted on top of the membrane.

Map showing location of Seneca Wastewater Treatment Plant southeast of the Minnesota River and northwest of Highway 13.  The Seneca Community Solar Garden is perpendicular to Highway 13, to the east of the plant.

Map of Plant and Solar Garden

Project Updates

Project Update - March 3, 2021 273 kB

Project Update - December 2019 (PDF) 237 kB

Project Contacts

For information, please contact:


Tim O'Donnell, MCES Project Citizen Liaison, 651.602.1269 or
Jason Peterson, Project Manager, 651.602.1614

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