West Basin approves $24.8m control-system replacement despite cost challenge
West Basin Municipal Water District, California · Meeting date: October 26, 2026 · Published: October 27, 2026
West Basin Municipal Water District has authorised Tetra Tech to begin construction on the replacement of the control backbone serving its recycled-water facilities. The 3-1 vote moves the project into construction with a guaranteed completion date of 31 December 2029.
Key points
- The board approved $22,653,892 of construction services under Tetra Tech’s progressive design-build contract, taking the contract’s not-to-exceed value to $24,776,303.
- Staff said the overall programme’s maximum anticipated cost is $26.5 million, compared with an approximately $15 million estimate made in 2024.
- The replacement addresses unsupported control-system equipment and is intended to provide a modern, secure and vendor-supported platform for recycled-water operations.
- Director Desi Alvarez voted against the measure, arguing that West Basin should use the off-ramp to rebid the now better-defined scope.
Full report
West Basin Municipal Water District has approved a $22.65 million guaranteed maximum price (GMP) to move its distributed control system (DCS) replacement into construction, committing a total of $24.78 million under its progressive design-build contract with Tetra Tech.
The board approved the measure 3-1 on 26 October, with Director Desi Alvarez dissenting. The GMP covers the remaining design work, equipment and software procurement, programming, installation, commissioning, testing, five years of 24/7 support and spare parts, according to staff.
The project replaces the backbone control system for West Basin’s recycled-water operations. Staff said the existing system was found in 2021 to be largely unsupported, exposing the district to an increasing risk of a prolonged outage. The new system is intended to be vendor-supported for decades, with dedicated 24/7 support and expanded documentation and redundancy.
The board’s approval represents the go/no-go point in the progressive design-build process. Had directors rejected the GMP, West Basin could have ended the Tetra Tech contract, taken ownership of work completed to date and either rebid the remaining work or discontinued the project.
Staff said the overall project’s maximum anticipated cost is $26.5 million, compared with an approximately $15 million estimate in 2024. The principal scope change identified during design was the discovery of 4,800 additional input/output points, on top of the roughly 10,000 identified in a 2021 audit. Each point must be transferred from the old system, programmed and added to operator screens.
Other cited cost drivers included $3 million for five years of post-project support, spare parts and prepaid subscriptions; at least $2 million in higher computing-component costs since 2024; approximately $400,000 from software sales-tax changes and tax increases; and approximately $2 million associated with an additional 3.5 years in the project schedule. Staff said value engineering had reduced total costs by at least $1.2 million.
An independent estimate by owner’s adviser Arcadis put the GMP at $24.1 million, $1.5 million above Tetra Tech’s final GMP, staff said. The GMP includes $10.4 million of construction costs, $1.4 million in district contingency for district-directed changes or government impacts, $870,000 in design-builder contingency and $690,000 in optional allowances.
Alvarez argued that the district now had enough project information to competitively rebid the work. “The increase that we’re looking at here is significant,” he said, noting that the cost had risen sharply from the initial estimate. He also said a proposed backup potable-water connection needed to support DCS shutdowns could add around $1 million beyond the DCS programme.
Staff countered that rebidding would introduce further delay and cost. It estimated that even a three-month rebid process could add about $1.5 million in material costs, while a new contractor would need to reassess field conditions and assume responsibility for complex cutovers. The GMP provides for completion by 31 December 2029, with system cutover and associated shutdowns planned for the first quarter of that year.
This summary was generated by AI based on the source document and may contain errors.
Source: Board of Directors Meeting, West Basin Municipal Water District