Empire Wastewater Treatment Plant (WWTP) Solids Improvements

MCES Project Nos. 807400, 807415, 807825, and 807826

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Project Updates: March 29, 2024 - Phase I (PDF) and Phase II (PDF).

Project Description

These projects increase capacity for solids storage and improve wastewater solids processing (Capital Program 8074) and improve and renew equipment and facilities (Capital Program 8078) at the Empire WWTP.  

These changes will also increase energy efficiency at the plant and help Metropolitan Council Environmental Services (MCES) operate the plant efficiently and cost-effectively into the future. Aerial photo of Empire Wastewater Treatment Plant

This project will be completed in two phases.  

Phase 1
Phase 1 construction, valued at $27 million, will occur between 2019 and 2021. Improvements include: 

  • Biosolids Pad Improvements - The biosolids storage pad is being expanded, resurfaced, and covered in order to increase storage capacity. Other improvements include a truck bay expansion, and drainage improvements. 

  • Road Improvements - Repair and reconstruct deteriorated asphalt road at Empire WWTP, including improvements to drainage facilities. 

  • Boiler System Improvements – The current boiler system is near the end of its service life and will be replaced. Along with a new boiler system, a sludge pumping station, waste gas flare, and new biogas treatment building will be installed. Biogas improves fuel quality in preparation for a future combined heat and power system that will better meet future plant-wide heating needs.  

  • High Strength Waste Receiving - Installing a new fill station and waste storage tanks, piping valves and controls to increase our biogas production for use as quality fuel in future combined heat and power system. 

  • Electrical improvements – To address plant-wide arc flash issues, MCES will add a new transformer and breaker, replace switch gear and motor control centers (MCCs), and re-cable existing transformers. 

Phase 2
Phase 2 construction, valued at $25 million, will occur between 2021 and 2023. Improvements include:  

  • Digester Improvements – New covers, mixing systems, and heating systems for Empire’s secondary digesters will more efficiently use existing tank volume to increase solids processing and storage capacity of the existing digestion system. 

  • Biogas Treatment and Storage – Hydrogen sulfide (H2S) and Siloxane removal systems will treat the digester gas before use as fuel in a new combined heat and power system. Increased biogas storage volume will increase use of biogas as fuel for on-site use.  

  • Combined Heat and Power System (CHP) – A new 1,000 kW biogas fueled engine generator will generate electricity and heat (in the form of hot water) for on-site use. Biogas generated from the digestion process and treated by the new H2S and Siloxane removal systems will provide fuel for the new CHP system.

Substantial completion of the project is tentatively scheduled for December of 2022, with final completion following in February 2023. 


Project Schedule

Project timeline showing Phase 1 Planning and Design from 2012 to 2019 Construction from 2020 to 2022 at a cost of $27 million and Phase 2 Planning and Design from 2012 to 2021 Construction from 2022 to 2024 at a cost of $20 million.

Project Updates

Project Update - Phase I - March 29, 2024 (PDF) 282 kB

Project Update - Phase II - March 29, 2024 (PDF) 232 kB

Project Update - Phase I - February 2024 (PDF) 216 kB

Project Update - Phase II - February 2024 (PDF) 284 kB

Project Update - Phase I - January 2024 (PDF) 297 kB

Project Update - Phase II - January 2024 (PDF) 271 kB

Project Staff

Project Manager: Heidi Hutter, Principal Engineer, Plant Engineering
Council's Authorized Representative: Marie Cramer, Principal Contract Administrator, Construction Services
Assistant Council's Authorized Representative: Matthew Amundson, Contract Administrator, Construction Services

Project Contacts

For information, please contact:

Email: [email protected]
Phone: 651-602-4618 (Marie Cramer)