January 11, 2005
 

SUBJECT: Award of a Contract for Engineering Design and Construction Support Services for Digester Rehabilitation at the Water Pollution Control Plant (F0412-24)

REPORT IN BRIEF

Approval is requested for the award of a contract to Carollo Engineers of Walnut Creek to provide engineering design and construction support services for the rehabilitation of one of four digesters at the Water Pollution Control Plant for the Public Works Engineering Division (Project No. UY-04/01-07).

BACKGROUND

The Sunnyvale Water Pollution Control Plant (WPCP) has four “floating cover” anaerobic digesters which are an integral part of the wastewater treatment process.  Digesters #1 and #2 were constructed in 1955, #3 was constructed in 1961, and #4 was constructed in 1969.  The digester covers are rigid steel structures which were fabricated specifically for the Sunnyvale WPCP.  The oldest covers are nearing fifty years of age and may be past their useful life as there are some indications of failure in the covers' steel sheeting.

The sludge drain lines associated with each digester are the same age as the digesters and also need restoration.  The City recently had to make repairs to a leak in the #4 digester line.

Although all four anaerobic digesters need rehabilitation work, only one digester can be taken off-line at a time.  For that reason, the requested contract is for engineering design and construction support for the rehabilitation of only one digester.  The award of contracts for the remaining digesters will be recommended to Council sequentially over the next few years.

In addition to digester rehabilitation, the requested contract will result in process improvements.  For example, the design will include the installation of a gas conditioner which will improve the quality of the gas being removed from the digesters for use in the City’s Power Generation Facility (PGF).  The improved gas quality will make it possible to extend the maintenance intervals for the PGF generator sets.

The design will also improve the mixing of biosolids for greater methane production and replacement.  This will be accomplished through a redesign of ancillary equipment, including the heat exchanger sludge pump, control valves, recirculation blowers, and other equipment associated with the digester.

DISCUSSION

In 2003, Request for Proposals No. F0206-104 was issued, seeking proposals from qualified engineering firms for engineering design and construction support services related to the rehabilitation of all four anaerobic digesters, three digester drain lines and miscellaneous ancillary equipment at the Water Pollution Control Plant.  Two proposals were received and reviewed by an evaluation team who determined that Carollo Engineers was the most qualified proposer, based upon its experience with process and control and seismic/structural analysis as well as specific relevant experience with digester projects in several Bay Area communities.

Initially, a scope of services and fee was negotiated for the preliminary design services and analysis, including an evaluation of alternative technologies; and Council awarded a contract to Carollo Engineers for that phase of the work on February 24, 2004 (RTC 04-061).  This first phase has now been completed, and a scope of services and fee have been negotiated for the second phase of the project.

Staff recommends that Council authorize work to progress by awarding a second contract to Carollo Engineers to provide engineering design and construction support services for the rehabilitation of the first digester.

FISCAL IMPACT

Project costs are as follows:

Funds are available in Capital Project #824300 - Replacement of Digester Lids.

RECOMMENDATION

It is recommended that Council award a contract, in substantially the same form as the attached draft and in an amount not to exceed $502,134, to Carollo Engineers for engineering design and construction support services related to the rehabilitation of one digester at the Water Pollution Control Plant.

Prepared by:

Elaine Wesely

Purchasing Officer

Reviewed by:

Mary J, Bradley

Director, Finance

Reviewed by:

Marvin Rose

Director, Public Works

Approved by:

Amy Chan

City Manager

ATTACHMENTS

Draft Consultant Services Agreement(PDF)