Title
Contract No. 2300154
PS 2 Bar Rack Replacement and Grit System Improvements
CIP #211007/BCE Score: 75.7
Body
Agenda of: September 25, 2024
Item No.: 2024-284
Amount: $224,985,000.00
TO: The Honorable
Board of Directors
Great Lakes Water Authority
FROM: Suzanne R. Coffey, P.E.
Chief Executive Officer
Great Lakes Water Authority
DATE: August 30, 2024
RE: Contract No. 2300154
PS 2 Bar Rack Replacement and Grit System Improvements
Vendor: Commercial Contracting Corporation
MOTION
Upon recommendation of Navid Mehram, Chief Operating Officer - Wastewater Operating Services, the Board of Directors (Board) of the Great Lakes Water Authority (GLWA), authorizes the Chief Executive Officer (CEO) to enter into Contract No. 2300154, “PS 2 Bar Rack Replacement and Grit System Improvements” with Commercial Contracting Corporation, at a cost not to exceed $224,985,000.00 for a duration of 2,008 days; and authorizes the CEO to take such other action as may be necessary to accomplish the intent of this vote.
BACKGROUND
The Pump Station 2 Rack and Grit (PS2RG) processing system for the Water Resource Recovery Facility (WRRF) was constructed in 1990 and last improved in 2015. The PS2RG system removes floating debris and grit from the waste stream before it enters the primary circular clarifiers for further treatment. It is estimated this system currently removes a combined ~15 tons per day of screenings and grit from Pump Station No. 2 influent. The existing system for PS2RG operates at 15% screenings removal efficiency and 32% grit removal efficiency. We estimate, as a result of this poor efficiency, that approximately 64 tons per day of screenings and grit pass through this process area and travel further into other plant processes, thereby causing other issues further downstream, such as greater wear and tear on pumping or solids processing equipment, or higher inorganic solids content making processing of the biosolids more difficult. The processing of biosolids is increasingly difficult during wet weather due to the inefficiencies of screenings and grit removal being even more burdensome on the rest of the treatment process areas. Sending these screenings and grit further down the system results in higher operations and maintenance costs because they are being processed by systems that weren’t designed to treat them. Ineffective handling of screenings and grit creates a risk of the National Pollutant Discharge Elimination System (NPDES) permit issued by Michigan Department of Environment, Great Lakes, and Energy (EGLE) violation due to potential treatment train or equipment failures, or water quality characteristics being affected by increased loading of screenings/grit throughout the process.
This project was identified in the most recent Wastewater Master Plan, finalized in 2020, and “The Master Planning evaluation confirms that it is imperative that these projects move forward in a timely fashion to maintain the EGLE/NPDES required capacity by improving the reliability of the existing system”. To address these challenges and the reliability of the WRRF, GLWA contracted the engineering firm of Hazen and Sawyer (Hazen) in October 2020 to perform planning, preliminary design, detailed design, and construction services for the PS2RG project. The design team, along with GLWA, evaluated 36 combinations of solids removal technology to determine which design concept balanced performance criteria and cost most effectively. The improvements to increase reliability and efficiency of this process include replacing the existing bar screens with new screens that have narrower openings (Currently ¾”, reducing to ¼”), adding two additional bar screens to maintain fluid capacity through the narrower openings, replacing the existing screenings conveyor belt with a sluicing trough flowing to dual drum screen and compactors, retrofitting the existing aerated grit tanks with vortex grit removal technology, and building a new grit processing facility including grit classifiers paired to each vortex grit tank for grit washing/dewatering.
JUSTIFICATION
By improving screenings and grit capture from Pump Station 2, before the flow enters our primary circular clarifiers, the reliability and resiliency of all downstream processes will be improved. The additional screenings recoalesce into large rag balls which can plug pumps, or wrap around the mixers in the aeration tanks, all leading to equipment failure and potentially process failure, which can lead to NPDES Permit violations. Better grit removal reduces abrasive wear and tear on downstream pumps, piping, and other equipment. Fewer process issues and less wear will lead to reduced maintenance costs and fewer equipment failures, ultimately improving the system reliability, and ensuring the WRRF is able to comply with the requirements of its NPDES permit. The improvements made in this project will affect several other projects currently in the wastewater Capital Improvement Program (CIP). A notable one is Pump Station 1 Rack & Grit improvements. This project will directly impact future improvements to the Pump Station 1 Rack & Grit improvements by incorporating all lessons learned from PS2RG on screening and grit handling equipment, and operational and maintenance challenges experienced. Another project directly influenced by the results of PS2RG is the Biosolids Improvements project and the sizing of the facility to handle solids into the foreseeable future for the GLWA WRRF. Failure to handle grit at the headworks portion of a WRRF hinders the ability of solids processing equipment and the future solid handling facility. This project will play a key role in the future of the capital improvement plan at the WRRF.
FINANCIAL PLAN IMPACT
Summary: Sufficient funds are provided in the financial plan for this project.
Funding Source: Sewer Construction Fund
Cost Center: Wastewater
Expense Type: Design (5421-892211.000-616900-211007)
Estimated Cost by Year and Related Estimating Variance: See table below.
Fiscal Year
FY 2025 Plan $9,528,776.00
FY 2026 Plan 27,559,660.00
FY 2027 Plan 57,268,909.00
FY 2028 Plan 57,268,909.00
FY 2029 Plan 45,516,852.00
FY 2030-34 Plan $27,841,894.00
Financial Plan Estimate $224,985,000.00
Proposed Contract Award 224,985,000.00
Estimating Variance $0.00
The Financial Plan Estimate above is the Revised Planned Spend by Fiscal Year from the Funds Approval, the change has been captured in the current CIP updates and will be reflected in the alignment.
COMMITTEE REVIEW
This item was presented to the Operations and Resources Committee at its meeting on September 11, 2024. The Operations and Resources Committee unanimously recommended that the GLWA Board adopt the resolution as presented.
SHARED SERVICES IMPACT
This item does not impact the shared services agreement between GLWA and DWSD.