FROM: James D. Herberg, General Manager
Originator: Kathy Millea, Director of Engineering
SUBJECT:
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TPAD DIGESTER FACILITY AT PLANT NO. 2, PROJECT NO. P2-128
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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 Brown and Caldwell to provide engineering services for Temperature Phased Anaerobic Digestion (TPAD) Digester Facility at Plant No. 2, Project No. P2-128, for an amount not to exceed $39,300,000; and
B. Approve a contingency of $3,930,000 (10%).
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BACKGROUND
Sludge is a byproduct of wastewater treatment that requires further processing to reduce pathogens and volatile organic carbon content so the remaining material can be beneficially reused in compliance with state and federal requirements. The Orange County Sanitation District (Sanitation District) uses anaerobic digesters at both plants to stabilize sludge prior to dewatering. Anaerobic digesters are large enclosed concrete structures that require pumping, mixing, heating, and gas handling systems. Anaerobic digesters also generate methane gas used to produce power and heat.
The Sanitation District has 18 digesters at Plant No. 2 that were built from 1959 through 1979. In 2017, the Sanitation District completed a comprehensive Biosolids Master Plan that provided a roadmap and framework for sustainable and cost-effective biosolids management options. The study recommended upgrading the existing digester complex by adding Temperature Phased Anerobic Digestion (TPAD) facilities including new thermophilic digesters and batch tanks, and refurbishing some existing digesters as the most resilient, lowest lifecycle cost.
RELEVANT STANDARDS
* 24/7/365 treatment plant reliability
* Safe, beneficial reuse of Biosolids
* Use all practical and effective means for resource recovery
* Comply with Government Code Section 4526: Select the "best qualified firm" an...
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