Without $1.5 million from voters, commercial and industrial development, even some major residential subdivisions, will come to a halt, say Hooksett Sewer Department representatives.

All of the town’s sewer capacity is either being used or has been pre-sold to developers for upcoming projects, said Sewer Commissioner Sid Baines.

In May, voters will be asked to fund $1.5 million of a $14 million expansion project to double capacity to 2.2 million gallons – the first time in 38 years tax dollars will pay for plant upgrades, said Superintendent Bruce Kudrick.

“For what that $1.5 million will give them, there should not even be a question,” said Baines. “If the (voters) refuse us, we’ll close our doors.”

This is the third time the warrant article will appear on the ballot and needs a three-fifths majority to pass. If approved, it’s expected to add 15 cents to 17 cents to the tax rate, or $45 to $51 to the tax bill for a $300,000 home.

Planning Board Chairman *** Marshall said that without the sewer expansion, single-family homes using septic and well will drive the town’s growth, putting strain on town services, especially schools.

Commercial and industrial projects can help to offset the residential tax rate.

Already the Sewer Department has started turning down some proposed projects in town, including two over-55 housing developments and a self-storage facility, making it impossible for those developers to bring their proposals to the Planning Board.

The Sewer Department has raised more than $6 million for the expansion, which was once enough to complete the work, Baines said. But delays and statemandated changes have driven up costs.

The Sewer Commission has agreed to a number of statemandated changes, including rerouting a small stream by cutting down trees, re-sloping the area and replanting trees. That change alone increased the project’s cost from $10,000 to $250,000, Baines said.

Hooksett’s treatment plant has undergone five expansions since 1970, but the only time taxpayers contributed was in 1970, to the tune of $125,000, 5 percent of the project’s cost, said Kudrick. In the early 1980s, the Sewer Commission started charging users a system development fee, paid upfront per user. That money is used to upgrade the plant as necessary. But with no more capacity to sell, the Sewer Department is stuck.

Even the 428-unit Head’s Pond development has sewer capacity for only 130 units, said developer David Campbell. He bought that capacity three years ago and won’t need to buy any additional for at least four more years.

If taxpayers approve the warrant article in May, the Sewer Department can do enough upgrades to convince the state to expand capacity by 10 percent, and then they can sell capacity to fund the remaining upgrades.

There is a possibility that the Cabela’s developer will pay for the $1.5 million upgrades if all goes well with the planning process this spring. But the money wouldn’t come to the town until the store’s possible opening in early 2010 and then the taxpayers’ debt would be repaid, said developer Gene Beaudoin.