The cost to construct the 8.2-mile segment of the Napa Valley Vine Trail from Calistoga to St. Helena has risen by $420,000, owing in part to an inaccurate forecast of funding needs by the Napa Valley Transportation Authority.

The total cost of the trail segment, which opened to the public in August, has jumped 28% over roughly the past two years, from an original projection of $13.2 million to now $16.96 million, including the latest increase.

Reasons given by the authority for the increases include construction delays related to work on a Pacific Gas & Electric Co. gas line. Megan McFarland, a PG&E spokesperson, previously said much of the work to replace the gas pipeline had been completed by June 2022, before the Vine Trail project broke ground in July 2022.

The most significant increase, $1.9 million approved by the transportation authority’s board in September, went to settle a claim about time-related compensation costs with Santa Rosa-based Ghilotti Construction Co., which built the trail, and to close out the construction contract.

The latest increase of $420,000, approved at a Dec. 18 board meeting of the transportation authority, was needed to repair recent storm damage and pay Ghilotti for carrying out an “extensive punch list of items” at the end of construction that were beyond the original scope of the contract, according to Grant Bailey, program manager for the agency.

He said staff had underestimated in September the additional costs of the extra, approved work on the trail.

“NVTA’s construction management team, myself included, did not accurately forecast the budget needs,” Bailey said at the December meeting.

The increase also covers disputed extra work items carried out by Ghilotti, which Bailey said have partial merit for payment, but weren’t “formally agreed upon.”

The latest funding allocation is covered by money from Regional Measure 3 — an increase to Bay Area bridge tolls that voters approved in 2018, to raise funds for highway and transit improvements. Past increases were split between project stakeholders, including Napa County, St. Helena, Calistoga and the nonprofit Napa Valley Vine Trail Coalition.

Much of the cost overrun could end up being filled by a roughly $3 million claim submitted by the transportation authority to PGE in September that contends the utility company is responsible for causing delays and cost overruns on the trail project because of unforeseen underground utility conflicts and utility replacement work.

If the claim is successful — it’s expected to be in review for a year — the authority will reimburse stakeholders for their additional contributions.

The new $420,000 cost bump would also be backfilled by that possible funding should the claim succeed, allowing for the bridge toll money to be used for other purposes.

Transportation board member Mark Joseph, who sits on the city council in American Canyon, on the opposite end of the valley, said at the December meeting that some bridge toll funding is set to go toward transportation projects for the city, and the use of the funds for the Vine Trail could impact the funding that’s available for such projects.

But he added that the vine trail segment is “really important.”

“Just everything that could go wrong went wrong, including weather,” Joseph said. “So it’s unfortunate, but hopefully this is the end.”

Distributed by Tribune News Service