EBMUD Digester Upgrade – Wastewater Treatment Plant Upgrade – Phase 1

Location: Oakland, CA

Owner: East Bay Municipal Utility District (EBMUD)

Contract: $24.5 Million

Role: General Contractor

Delivery Method: Design-Bid-Build

Result and Benefit to Client

A quality project was successfully delivered on time and within budget with no safety issues, claims or liquidated damages. There were no unscheduled interruptions to the plant’s treatment capacity during construction.

Project Description

This project was Phase 1 of a two-phase upgrade to EBMUD’s main water treatment plan. The project included replacement of digester covers past their useful life, installation of a pile supported gas collection header, and modifications to the power generation station.

As the General Contractor, Monterey Mechanical constructed:

  • 4 new 95-ft. diameter steel fixed digester covers
  • 16 new 36-inch-diameter draft tube mixers and appurtenant piping
  • Instrumentation, controls, and electrical facilities
  • Structural steel overhead pipe rack and pile-supported foundations to support a new 840 LF of 36-inch-diameter stainless steel digester gas headers
  • New digester gas-fired hot water boiler on pile-supported foundations

We also designed, furnished and installed new digital controls on three existing 2-MW engine generators. The work included touch screen graphical HMI control stations, PLC panels, MCCs, engine-mounted instrumentation, controls, and programming.

Engine control system work included modifications of the natural gas and biogas blending systems along with the emissions sensing system requiring modifications and refurbishment of various engine-related equipment, cooling water pumps, and heat exchangers.

A scaffolding system was used to install the new digester covers. The scaffolding system could be lowered incrementally for installation of coating after covers were in place.

Monterey Mechanical self-performed approximately 68% of the work. We retrofitted the existing concrete digester structures to install the new covers. We performed the civil work and installed all process equipment and piping. We procured and installed complex equipment and electrical systems, coordinated with local utilities and the Bay Area Air Quality Management District.

Challenges | Solutions

The primary challenges on Phase 1 of the Digester Upgrade – Wastewater Treatment Plant Upgrade were maintaining continuous plant operations during construction, avoiding schedule delays, and ensuring there was no miscommunication that could impact the quality, schedule, or budget.

Monterey Mechanical maintained continuous plant operations by sequencing construction to take only one digester out of service at a time. We developed a startup, testing and commissioning plan to document testing and readiness for service, which was successfully implemented.

We coordinated electrical and controls work with all process equipment procurement to ensure trouble-free system start-up activities. We worked with the covers manufacturer to expedite delivery to stay ahead of the construction schedule.

Monterey Mechanical employed a cooperative partnering relationship with all stakeholders early in the project with constant communication to foster cooperative relationships.

Leaving nothing to chance, Monterey Mechanical proactively verified that required scopes of work had been included by conducting a thorough analysis of the subcontractors’ proposals during the bidding phase.

To assure site safety, quality construction, and to resolve any issues in real time that might interrupt the schedule, we located our Project Manager, Safety Manager, and engineers on site.