FROM: James D. Herberg, General Manager
Originator: Kathy Millea, Director of Engineering
SUBJECT:
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PRIMARY SEDIMENTATION BASINS NO. 3-5 REPLACEMENT AT PLANT NO. 1, PROJECT NO. P1-126
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GENERAL MANAGER'S RECOMMENDATION
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RECOMMENDATION: Recommend to the Board of Directors to:
A. Approve a Professional Design Services Agreement with Black & Veatch to provide engineering services for Primary Sedimentation Basins No. 3-5 Replacement at Plant No. 1, Project No. P1-126, for an amount not to exceed $14,163,000; and
B. Approve a contingency of $1,416,300 (10%).
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BACKGROUND
Primary treatment is the second of three liquid treatment steps at Orange County Sanitation District (OC San) Plant No. 1. Primary treatment reduces wastewater suspended solids using large concrete basins known as primary clarifiers or primary sedimentation basins.
Plant No. 1 includes two sets of primary clarifiers; a set of 26 rectangular clarifiers and a much older set of three circular clarifiers constructed in the late 1950s and early 1960s. The rectangular clarifiers have enough capacity for normal flows, but in the event of peak wet weather flows or when one side the rectangular basins must be taken out of service for maintenance or condition assessments, the circular basins are needed.
A concept study was performed in 2017 to assess the condition of the circular clarifiers and related facilities and to identify recommended improvements. The study recommended replacing rather than rehabilitating them.
RELEVANT STANDARDS
* Comply with California Government Code ?4526: Select the "best qualified firm" and "negotiate fair and equitable fees"
* Protect OC San assets
* 24/7/365 treatment plant reliability
PROBLEM
The circular primary clarifiers at Plant No. 1 and many of their associated support facilities including the primary odor control facility are nearing the end of their useful life. In fact, the circular clarifiers were taken...
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