FROM: Robert Thompson, General Manager
Originator: Mike Dorman, Director of Engineering
SUBJECT:
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PRIMARY CLARIFIERS F AND G ROTATING MECHANISM REHABILITATION AT PLANT NO. 2, PROJECT NO. FE23-09, SPECIFICATION NO. S-2024-612BD
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GENERAL MANAGER'S RECOMMENDATION
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RECOMMENDATION:
Approve a contingency increase of $850,500 (27%) to the existing Services Contract with Vicon Enterprises, Inc., for Primary Clarifiers F and G Rotating Mechanism Rehabilitation at Plant No. 2, Project No. FE23-09, Specification No. S-2024-612BD, for a new total contingency of $1,323,000 (42%).
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BACKGROUND
The A-side Primary Clarifiers (clarifiers), originally constructed in 1962, consist of four circular clarifiers responsible for treating non-reclaimable flows at Orange County Sanitation District (OC San) Plant No. 2. During normal operations, three clarifiers are in service, while the fourth is kept in reserve as a backup unit. In February of 2023, Clarifier F failed due to metal loss from corrosion at the connections between the rake arms and center cage structure, which resulted in the failure of the rotating mechanism. An inspection of Clarifier G showed similar levels of corrosion, raising concerns that its rotating mechanisms could fail at any time. Consequently, Clarifiers F and G have remained offline since then. The A-side is currently operating with only Clarifiers D and E in service.
RELEVANT STANDARDS
* Meet volume and water quality needs for the GWRS
* 24/7/365 treatment plant reliability
PROBLEM
Currently, only Clarifiers D and E are running, providing no redundancy during dry weather operating conditions due to Clarifiers F and G being out of service. The reduced A-side treatment capacity is straining the secondary treatment process and impacting secondary effluent quality when operating in separated mode for the Orange County Water District's Ground Water Replenishment System (GWRS).
Following the completion of sandbl...
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