Staff recommends the City Council award a contract for WO 20-19 WRF Primary Digester Cleaning & Improvements to MP Environmental Services Inc. in the amount of $495,719.28.

The W.O. 21-19 WRF Primary Digester Cleaning & Improvements project will clean one primary digester at the Water Reclamation Facility. Cleaning the digester is scheduled to occur every 5 to 7 years to remove contents that cannot be broken down. The cleanup has been deferred for the past several years due to the ongoing construction activities of the multi-year plant upgrade project and is overdue. While the digester is down for cleaning, the following additional maintenance activities will occur:

• The digester contents are continually mixed with digester gas using long 2" stainless steel pipes, known as gas lances, that inject gas into the digester at the base of the tank and agitate the digester contents.  These components are original equipment from the 1980s and are no longer functioning at their intended capacity and require replacement. 
• The digester roof has 3 large rectangular mixer access openings.  These large openings have a two-piece hinged access door, which is prone to leakage, and is starting to deteriorate around the hinge bolt holes.  The metal that is compromised is to be removed and the current assembly is to be replaced with a one-piece, non-hinged design that will not only replace the metal that has deteriorated, but will also mitigate the leak points present.
• The perimeter seal around the outer edge of the tank roof seals the metal roof structure to the concrete tank walls.  This seal has been repaired in-place over the top of existing seal settlement and is due to be removed completely and resealed.  This seal is the main gas seal that prevents the hazardous digester gases (which include methane and H2S gas) from leaking out into the atmosphere.  
• The exterior tank roof coating has failed and needs to be sand blasted and re-coated before permanent damage to the roof occurs.

The project was advertised on March 19, 26, and April 2, 9, 16, 23, 2021 in the Yellowstone County News and on the City's website. Bids were opened on April 27, 2021. Two bids were received. MP Environmental Services Inc. submitted the lowest responsible bid.

City Council may:

• Award W.O. 21-19 WRF Primary Digester Cleaning & Improvements to MP Environmental Services, in the amount of $495,719.28; or,
• Not award a contract and reject all bids.  If this project is not constructed, required and overdue maintenance will not be performed and the digester will continue to accumulate non-digestible solids and not achieve proper mixing, leading to operating problems.  Failures to replace seals and other sealing components could lead to gas leaks which pose environmental and safety risk, and lead to the digester running outside of state compliance limits.  Lastly, delaying roof painting activities could lead to additional roof corrosion and premature roof repair or roof replacement.  

The following bids were received and evaluated:
 

NAME OF BIDDER	BASE BID
MP Environmental Services, Inc.	$495,719.28
Star Service, Inc.	$698,000.00

The funding for the project was budgeted in the FY21 wastewater operations and maintenance fund in the amount of $800,000.