Santa Rosa Board approves Llano Trunk rehabilitation GMP, construction management contract

Santa Rosa’s Board of Public Utilities on April 17 approved a progressive design‑build guaranteed maximum price (GMP) and related construction management and engineering services for the Llano Trunk Rehabilitation Phase 1 project.

The board voted unanimously, with Board Member DeWitt absent, to incorporate a $14,705,413.09 GMP for construction services with SAK Construction LLC, approve a 15% contingency for that GMP, and authorize engineering‑during‑construction services not to exceed $711,036.70. The board also approved a project work order with Coastal Civil Engineering for construction management and inspection services in an amount not to exceed $628,202.

The project will rehabilitate approximately 8,100 linear feet of 66‑inch trunk sewer that conveys roughly two‑thirds of the city’s wastewater between the Laguna Treatment Plant and north of the Lawn o/Todd Road intersection. Staff recommended cured‑in‑place pipelining (CIPP) as the trenchless rehabilitation method to limit excavation in areas with high groundwater and environmental constraints. The board heard staff explain bypass pumping needs, a temporary on‑site wet‑out facility for the large liner, and a June 15–Oct. 15 construction window tied to permit conditions.

City staff described the progressive design‑build delivery as advantageous for this complex job because it lets the contractor collaborate on constructability, refine work limits, and specify long‑lead equipment before construction. Under the agreement approved today, the design‑builder completed approximately 75% design and proposed a GMP. City staff and an independent auditor reviewed and negotiated that cost; staff said the auditor recommended acceptance after the design‑builder reduced its original proposal by roughly $500,000.

Rachelle Amayeda, associate civil engineer and the project presenter, told the board the liner is structural with an estimated service life of about 50 years and that portions of the existing reinforced concrete host pipe show exposed rebar. She said bypass pumping will discharge to the Laguna Treatment Plant’s emergency holding basin and that, per permit requirements, construction is limited to the June–October window. Amayeda also noted typical contingencies that would remain the city’s responsibility, including augmenting bypass pumping in the event of an extreme rain event or paying for unforeseen field conditions such as an unexpectedly high groundwater table.

The approved contract change order packages consist of three parts: (1) the engineering services during construction (not to exceed $711,036.70); (2) the GMP for construction ($14,705,413.09); and (3) a 15% GMP contingency yielding a total not‑to‑exceed construction amount of $17,622,261.75. Separately approved was the project work order for construction management and inspection services with Coastal Civil Engineering ($628,202).

Board members asked technical and contract questions before the vote. Board Member Wright asked about the resin supply for the liner and whether tariffs or supply chain issues might affect the schedule; staff said the resin source is currently Texas and no tariff impacts were reported by the contractor at this time. Wright also asked about liquidated damages and staff confirmed the existing contract includes liquidated damages if construction exceeds the contract time. When asked what would happen if outstanding permits or tasks were not finished by the target date, staff said the notice to proceed would not be issued, the GMP would be removed from the contract, and the city could either renegotiate the GMP or revert to preparing construction‑ready documents for a traditional bid process.

The board’s action allows staff to proceed with final design and procurement steps with the intent of starting construction in 2025 if outstanding permit conditions are met. If those items are not complete by the May 31 deadline in the change order language, the GMP will be removed and the city will not proceed with construction this year, staff said.

The project team emphasized that the Llano Trunk segment is the highest priority for rehabilitation because of the pipe’s condition and its role conveying the majority of the city’s wastewater. Staff said the progressive design‑build approach shifts some design risk to the design‑builder and can accelerate schedule and coordination for permits and work limits.

Implementation details and next steps include finishing the design, securing remaining permits by mid‑May where feasible, issuing the notice to proceed if all conditions are satisfied by May 31, and proceeding to construction within the June 15–Oct. 15 work window. If construction is delayed into 2026, staff said contracts with the selected consulting firm will be amended to reflect the later schedule and fees.

Votes at a glance: the motion to approve the change order and the project work order was moved by Vice Chair Arononi and seconded by Board Member Wright; the roll call was: Wright (Aye), Mullen (Aye), Bartholow (Aye), Bedingford (Aye), Vice Chair Arononi (Aye), Chair Galvin (Aye). Board Member DeWitt was absent.

Project proponents and staff said they will return to the board with construction progress and post‑construction debriefs once work is complete.