Ascension Parish government has one bidder planning to make a proposal for a 30-year contract to finance, design, build and run a $300 million to $500 million regional sewer system for the unincorporated parts of the parish.

A collection of companies led by GSA Consulting Engineers, of Gonzales, was the only group to meet the Monday deadline to submit a letter of intent and put down a refundable $75,000 deposit, parish officials said Wednesday.

The lack of competition for what will become a long-term marriage among the winning bidder, parish government and Ascension ratepayers comes after three prospective bidders asked earlier this month for three to six more months to work on proposals.

“Although the bid is within the scope of our business, it has been our experience for projects such as this elsewhere, response times for the RFP submission are double (or more) than that of this project (60 days),” Michael Rigby, of American Water Enterprises, wrote in an Oct. 2 email to parish officials.

American Water Enterprises is a subsidiary of Voorhees, New Jersey-based American Water, which bills itself as the nation’s largest publicly traded water and wastewater utility. Rigby asked for at least three more months.

Others seeking an extension were Hartman Engineering, of Louisiana, and Cintra, of Austin, Texas, according to a letter and emails obtained through a public records request.

Despite years of discussion and study, the parish has found itself unable to pay for the big sewer project without additional tax revenue, even with low-interest government loans because of a small initial customer base.

With the latest bidding effort, parish leaders are reverting back to a public-private partnership, a concept tried at least twice before without success.

Under the partnership, the bidders provide most of the upfront money and risk, then build and run the sewer system and earn back their costs, plus a profit, on sewer and hookup fees that residents pay.

Proposals aren’t due until Nov. 9, but bidders had to submit their letters of intent and deposit by Monday.

Lester Kenyon, parish government spokesman, said Thursday that under the parish’s request for proposals, only companies that have submitted the letter and deposit can submit bids.

GSA has been involved for years in discussions on the system and has had parish contracts for preliminary work tied to aborted attempts to finance and build the system.

American Water was GSA’s competitor in a previous attempt at a public-private partnership in 2010 and 2011. GSA and then-partner Integra Water won, but the plan fell apart in contract negotiations.

Hartman has offices in Prairieville and Kenner and would lead a group that includes Cajun Industries, Evans-Graves Engineers Inc. and Severn Trent Environmental Services. Hartman asked for six more months.

Cintra wanted two to three months.

Before Monday’s deadline passed, Parish President Tommy Martinez said he didn’t plan on extending deadlines and left any changes up to the Parish Council, which has had divided views on the question.

Councilman Randy Clouatre, who, as council chairman, sets meeting agendas, said Thursday he did not know whether the council would want to raise the issue but suspected that having only one bidder would generate some conversation.

Councilwoman Teri Casso, who has pushed for more time, said she is disappointed there is only one bidder.

“If we’re going to go buy something that costs $500 million, I would want more than one thing to look at,” she said.

But an extension or even restarting the process would mean the long-discussed sewer effort would be decided by a new Parish Council and administration.

In September, council members had an extended debate on the 60-day deadline and preserving their ability to vote on the winning bidder before their terms end in January.

Several council members who resisted a deadline extension aired concerns about squandering a hard-fought opportunity to deal with the parish’s sewer problems.

The time frame the council settled on — bids were going to be due in 32 days — gives the departing council a chance to vote.

Councilman Daniel “Doc” Satterlee is among those who had favored holding to the deadline even as companies asked for more time.

“Well, what do you tell the other people that didn’t procrastinate and are ready?” he asked.

Casso and Satterlee were re-elected Oct. 24, but the 11-person council will have three new members in January, with expected departures and an incumbent’s defeat Oct. 24.

Martinez has said he would include the parish’s president-elect on contract negotiations. Kenny Matassa and Clint Cointment are headed to the Nov. 21 runoff in that race.

Follow David J. Mitchell on Twitter, @NewsieDave.