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Item 1.B.4.
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| City Council Regular | |
| Date: | 02/14/2022 |
| Title: | Bid Award: W.O. 22-17 WRF Primary Digester No. 1 Cleaning and Improvements |
| Presented by: | Debi Meling |
| Department: | Public Works |
| Presentation: | No |
RECOMMENDATION
Staff recommends the City Council award a contract for W.O. 22-17, WRF Primary Digester No. 1 Cleaning & Improvements, to MP Environmental Services, Inc. in the amount of $681,218.00.
BACKGROUND (Consistency with Adopted Plans and Policies, if applicable)
The W.O. 22-17 WRF Primary Digester No. 1 Cleaning & Improvements project will clean Primary Digester No.1 at the Water Reclamation Facility. The WRF has two primary digesters and one secondary digester. Cleaning the primary digester is scheduled to occur every 5 to 7 years to remove contents that cannot be broken down by natural biological processes. A similar digester cleaning process was completed in 2021 for Primary Digester No. 2. The cleanup has been deferred for several years due to the ongoing construction activities of the multi-year water reclamation plant upgrade project and is overdue. Digester No 1. was last cleaned in 2012. While the digester is taken out of service for cleaning, the following additional maintenance activities will occur:
- The digester contents are continually mixed with digester gas using long 2-inch 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 1980's and are no longer functioning at their intended capacity and require replacement. Some lances are degraded to the point of not operating and do not delivery gas as intended.
- The digester roof has three 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. The metal that is compromised will be removed and the current assembly will be replaced with a one-piece, non-hinged design.
- 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 and will be removed and replaced. This seal is the main gas seal that prevents the hazardous digester gases (which include methane and hydrogen sulfide gas) from leaking out into the atmosphere.
- The exterior tank roof coating has failed and needs to be sand blasted and re-painted before permanent damage to the roof occurs.
ALTERNATIVES
City Council may:
- Award W.O. 22-17, WRF Primary Digester No.1 Cleaning & Improvements, to MP Environmental Services Inc. in the amount of $681,218.00; 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.
FISCAL EFFECTS
The following bid was received:
The project was budgeted in FY22 using wastewater operations and maintenance funds. City staff determined the bid was reasonable based on the cost of the work on the other digester last year combined with the additional work necessary on this digester.
| Contractor | Base Bid |
| MP Environmental Services, Inc. | $681,218.00 |
The project was budgeted in FY22 using wastewater operations and maintenance funds. City staff determined the bid was reasonable based on the cost of the work on the other digester last year combined with the additional work necessary on this digester.