FROM: Robert Thompson, General Manager
Originator: Mike Dorman, 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
recommendation
RECOMMENDATION: Recommend to the Board of Directors to:
Approve a contingency increase of $849,780 (6%) to the existing Professional Design Services Agreement with Black & Veatch Corporation to provide design services for Primary Sedimentation Basins No. 3-5 Replacement at Plant No. 1, Project No. P1-126, for a total contingency not to exceed $2,266,080 (16%).
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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 which removes suspended solids using large concrete primary sedimentation basins. Plant No. 1 has 26 rectangular clarifiers constructed in the 1980s and 1990s and three circular clarifiers constructed in the late 1950s and early 1960s. Due to the current degraded condition of the circular clarifiers, they currently provide additional capacity during peak wet weather flows and when rectangular clarifiers are unavailable for maintenance or condition assessments. The project will replace the three circular clarifiers and related primary treatment facilities to restore reliable treatment capacity.
RELEVANT STANDARDS
• Ensure the public’s money is wisely spent
• 24/7/365 treatment plant reliability
PROBLEM
The original Professional Design Services Agreement included a 10% contingency to address changes to the original Scope of Work. A significant portion of the contingency has been used to reevaluate the rehabilitation versus replacement concept, perform system-wide electrical power system studies, review updated structural code requirements, and design a new primary effluent junction box. The new junction box reduces the need for bypass pumping during construction and provides a long-term hydraulic benefit by allowing the upstream junction box to operate at a higher water level. This improves peak wet weather flow handling and reduces the risk of an unanticipated primary overflow.
The remaining contingency is insufficient to complete additional design changes, including a temporary motor control center for the existing odor control facility during construction, pipe material revisions and design changes to address liquefaction settlement risks, and design modifications around existing piles to reduce construction risks and delays.
PROPOSED SOLUTION
Approve the contingency increase to complete the remaining design changes needed to address temporary electrical equipment for support construction sequencing, liquefaction settlement, and existing site conditions.
TIMING CONCERNS
Delaying approval could postpone authorization of the remaining design changes and delay design completion.
RAMIFICATIONS OF NOT TAKING ACTION
Without the additional contingency, OC San would need to remove or reduce portions of the design scope to remain within the existing agreement budget. This could require future projects to complete omitted work or increase construction risks.
PRIOR COMMITTEE/BOARD ACTIONS
April 2022 - Approved a Professional Design Services Agreement with Black & Veatch Corporation 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 approved a contingency of $1,416,300 (10%).
ADDITIONAL INFORMATION
N/A
CEQA
The project is exempt from CEQA under the Class 2 categorical exemptions set forth in California Code of Regulations sections 15302 Replacement or Reconstruction of Existing Structures and Facilities. A Notice of Exemption was filed with the OC Clerk-Recorder on April 29, 2022.
FINANCIAL CONSIDERATIONS
This request complies with the authority levels of OC San’s Purchasing Ordinance. This item has been budgeted (Budget FY 2026-27 and FY 2027-28, Section 8, Page 50, Primary Sedimentation Basins No. 3-5 Replacement at Plant No. 1, Project No. P1-126. This item will be funded from the CIP budget.
|
Date of Approval |
Contract Amount |
Contingency |
|
04/22/2022 10/28/2026 |
$ 14,163.000 |
$ 1,416,300 (10%) $ 849,780 (6%) |
ATTACHMENT
The following attachment(s) may be viewed on-line at the OC San website (www.ocsan.gov) with the complete agenda package:
• Presentation
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