FROM: Robert Thompson, General Manager
Originator: Mike Dorman, Director of Engineering
SUBJECT:
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CHEMICAL SYSTEMS REHABILITATION AT PLANT NO. 2, PROJECT NO. P2-135
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GENERAL MANAGER'S RECOMMENDATION
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RECOMMENDATION: Recommend to the Board of Directors to:
A. Receive and file Bid Tabulation and Recommendation for Chemical Systems Rehabilitation at Plant No. 2, Project No. P2-135;
B. Award a Construction Contract Agreement to Innovative Construction Solutions for Chemical Systems Rehabilitation at Plant No. 2, Project No. P2-135, for a total amount not to exceed $4,439,500; and
C. Approve a contingency of $443,950 (10%).
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BACKGROUND
Orange County Sanitation District (OC San) has a 120-inch, five-mile-long outfall and a 78-inch, emergency one-mile-long outfall. The National Pollutant Discharge Elimination System (NPDES) permit requires OC San to disinfect effluent when the 78-inch outfall is in operation. This may occur when the 120-inch outfall is scheduled for maintenance or during extreme high-flow events that exceed its capacity. The disinfection process involves adding sodium hypochlorite to destroy fecal coliform and other pathogens, followed by sodium bisulfite to dechlorinate the effluent and reduce environmental impact. The permanent Sodium Bisulfite Station has been taken offline due to its poor condition, and a temporary system has been installed for the 78-inch outfall effluent disinfection.
In addition, Plant No. 2 uses ferric chloride and an anionic polymer as coagulants in chemically enhanced primary treatment, which helps remove settleable solids. This process improves effluent quality and reduces hydrogen sulfide in digester gas. The anionic polymer system, located near the Primary Clarifiers, was constructed in 1988, and its electrical and instrumentation systems have not been upgraded since installation.
RELEVANT STANDARDS
* Comply with California Public Contract Code Section ...
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