FROM: Robert Thompson, General Manager
Originator: Mike Dorman, Director of Engineering
SUBJECT:
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DEWATERING CENTRIFUGE DIVERTER GATE IMPROVEMENTS AT PLANT NO. 1, PROJECT NO. FR1-0018
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GENERAL MANAGER'S RECOMMENDATION
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RECOMMENDATION:
A. Award a Construction Contract Agreement to Innovative Construction Solutions for Dewatering Centrifuge Diverter Gate Improvements at Plant No. 1, Project No. FR1-0018, for a total amount not to exceed $1,289,500; and
B. Approve a contingency of $193,425 (15%).
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BACKGROUND
The Orange County Sanitation District's (OC San's) Plant No. 1 Thickening and Dewatering (T&D) Building has three diverter gates installed. One diverter gate per dewatering centrifuge, at the basement level, to route unthickened solids, and wash water away from the centrifuge cake pump hopper to a drain during a centrifuge startup and shutdown.
RELEVANT STANDARDS
* Comply with California Public Contract Code Section 20103.8, award construction contract to lowest responsive, responsible bidder
* Maintain a proactive asset management program
PROBLEM
During a centrifuge startup, or water flushing cycle, water leaks through the closed diverter gate to the dewatering cake piston pump below, causing premature wear of the piston. Additionally, excessive water is being pumped to the biosolids cake silos creating a wetter cake, which impacts the truck loading process and biosolids handling costs.
PROPOSED SOLUTION
Award a construction contract to install three new water-tight diverter gates. The new diverter gates will be sourced from the same manufacturer that supplied the gates currently in use at Plant No. 2. These have demonstrated superior performance compared to the existing equipment at Plant No. 1.
TIMING CONCERNS
Delaying the project award increases the risk of premature wear or failure of the cake piston pumps.
RAMIFICATIONS OF NOT TAKING ACTION
If no action is taken, there is an increa...
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