Developers of a proposed mixed-use development at Napa Pipe have portrayed their project as a shining example of “smart growth” that would preserve Napa County agriculture by diverting future county housing to an old industrial site.

That’s not how the Napa City Council sees it. City officials cast the proposed 3,200-home project as a planning blunder of major proportions, jeopardizing city residents’ quality of life.

Generating 26,000 or more vehicle trips a day, most of them funneled onto Highway 221, Napa Pipe would worsen traffic between American Canyon and downtown Napa, consultant Harry Burrowes of dk Consulting said Thursday night.

City Public Works Director Jacques LaRochelle said Highway 29 in American Canyon, Highway 221 in front of Napa Valley Corporate Park as well as Soscol Avenue and Silverado Trail leading to downtown would have to be widened to six lanes to handle the added crush of vehicles.

All told, Napa Pipe would be expected to pay $60 million as its share of area street and highway improvements, with no guarantee that public matching money to actually build new road capacity would be forthcoming, Burrowes said.

Napa Pipe developers tout planned environmental features, yet “the development is very car-centered. It requires residents to drive everywhere,” Assistant City Manager Dana Smith said.

Napa Redevelopment Partners’ plan for Napa Pipe would be “unprecedented in its density and scale in the North Bay region,” Burrowes said. The project would create burdens on public services and Napa infrastructure that have not been fully measured, he said.

About 100 people turned out for the City Council’s special meeting on Napa Pipe. The council called the session earlier this week after negotiations with Napa County to bring Napa Pipe into the city collapsed.

As the city sees it, the 152-acre former industrial site should be planned to meet public needs. This might mean shifting some light industrial and corporation yard functions from the central city to Napa Pipe, freeing up sites for new housing close to schools, shopping and transit.

Napa County wants to use Napa Pipe to meet its mandated share of the Bay Area’s housing needs unless a long-term deal can be struck with Napa to absorb most of this housing.

City-county talks over bringing Napa Pipe into the city stumbled over the city’s inability to guarantee that it could meet 70 percent or more of the county’s housing share for the next 21 years.

The city could easily take 456 county housing units over the next seven years without hurting existing Napa neighborhoods, Jean Hasser, a city planner said.

Since a housing deal with the city is impossible in the short term, the county is planning to launch an environmental impact study for the Napa Pipe proposal. This study could take a year.

Burrowes said there is a good possibility that the planned project will be found “economically infeasible.” The promised lower-priced condos intended for so-called workforce housing may end up costing much more, he said.

During public comment, consultants to Napa Pipe said city figures for the project’s traffic and economic impacts were inflated. Because Napa Pipe would be a high-density, mixed-use development located near south county jobs, projected traffic counts could be 30 percent to 40 percent too high.

Napa Pipe would be willing to build its own sewage treatment plant, if necessary, consultants said. The impact on the city’s water system would be minimal if the project is allowed to tap a giant aquifer under the property, the council was told.

The council received a flurry of e-mails in support of Napa Pipe, with people saying they liked proposed artist studios and the project’s cultural amenities. Several others voiced concerns over traffic and water.

Judy du Monde, a Napa Pipe supporter, urged the council not to get locked into old ways of thinking. “It is past time to be bold,” she said. The smaller housing units proposed for Napa Pipe are exactly what the public needs, she said.

The city has reserved the right to sue Napa County if the outcome of Napa Pipe planning presents unacceptable burdens to the city. Until now, the council has been discussing the project in closed session as a topic of “anticipated litigation.”