ATTLEBORO -- Officials led by Mayor Kevin Dumas aim to sit down over the coming weeks to hammer out a plan to fund the city's share of development costs for a major revamping of downtown now being planned by the Attleboro Redevelopment Authority.

The process could become dicey, with the city wary that funds committed to the downtown project could jeopardize future city services and the redevelopment authority pushing for money to get the project off the ground.

Dumas said Tuesday he's committed to the effort, which will use a state-authorized District Improvement Financing plan (DIF) that taps into new tax revenue created by the project to help pay for it.

The new revenue is partially given to the project and partially to the city for ongoing services to residents.

Development of a specific plan that determines percent ages and dollar amounts based on best estimates of revenue will be long and complicated, Dumas said. `` The DIF is in its early discussion phases and we are going to be meeting weekly to discuss what it means,'' he said. `` There's much groundwork that needs to be done.''

Determining the percentage of the split and funding totals are a way off, said Dumas, who added, `` We're still not in a position to nail down any specific dollar amounts.''

Not only does the city have to figure out what it can dedicate to the project, it has to figure out how to implement and track the funding mechanism.

`` When setting forth on a new venture, you have to make sure you cover every aspect of how it will function,'' the mayor said. `` You can't leave any stone unturned. We have to know how it's going to work.''

The mayor's comments came in response to an ARA meeting Tuesday that laid out basic funding mechanisms for the first and most important phase of the downtown project -- the development of a river front district.

That's considered a key component of downtown redevelopment because it includes a commuter rail parking garage and new housing expected to spark other new housing.

Costs for getting the riverfront district ready for private developers are estimated to be $60 million.

The price tag includes acquisition of property, environmental analysis and cleanup, moving the city's public works yard, the installation of infrastructure such as water and sewer lines and construction of the parking garage.

The parking garage and associated improvements are alone expected to cost $31 million.

Officials estimate the city's share of the entire project at $15 million, but the numbers are not set in stone, ARA Executive Director Mike Milanoksi said. While the city is working on its financing plan, the ARA will be refining costs for the project. Results from both will be needed in the coming months to get local and state approvals.

The riverfront phase includes construction of a 900-car parking garage for the MBTA rail line and up to 500 condominium, townhouse or apartment homes along Ten Mile River -- all on a 26-acre parcel now used for surface MBTA parking, the city's public works yard and some private industry.

Phase I would open the river for recreational use, relocate Wall Street, create commuter access via Olive Street, establish about 30,000 square feet for new commercial development, build a new GATRA bus station and create a new road between Olive and Wall streets.

The ARA is in the process of completing an urban renewal plan which, when combined with the DIF plan, will give it the legal power and financial wherewithal to develop the area.

Both plans need state and local approval to go forward.

Milanoski is hoping both will be done this summer and submitted to local and state officials for approval to get the project rolling.

Overall funding for the riverfront district includes $14 million in state and federal grants already approved, $21 million in future state and federal grants likely to be approved, $10 million in land sales following site development and at least $15 million in local new growth tax money coming from the project area.

Milanoski said private developers would likely bring an estimated $157 million to the table to actually build the homes and commercial areas.

Under the DIF plan, local money would come from new taxes garnered from increasing values in the project area as well as the new construction.

However, with a strained municipal budget and calls to maintain and even expand city services, a crucial question is how much of that money initially will be available.

Value increases are expected in the fourth year of the project's 20-year build-out timeline. New taxes would first be realized for improvements to surrounding property and then in new construction, which would create new growth money.

Most of the estimates are tentative, but officials are honing the numbers for the presentation of a formal plan.

The mayor's assistant, Jim Merriam, who attended the Tuesday ARA session, said the problem is not simple from the city's perspective and agreed with the mayor that it will take some time to work out the numbers.

Committing new revenue to purposes other than direct city services needs to be done carefully, he said.

`` The concern is if we earmark future new growth, we may not have the income to fund future services,'' he said.

However, Milanoski said that without the development there won't be any new growth money, and the city center will continue to stagnate.

`` Without the investment, there won't be any money,'' he said.

ARA member David Ramsay, a town administrator by profession, said he worries about the city's ability to share the cost and suggested the way to fund the city share is through a tax override or borrowing.

Both Dumas and Milanoski said neither of those suggestions is an option.

Funding comes from the DIF plan, some other outside source or not at all, they said.

Milanoski said the city is opting for the `` pay-as-you-go method,'' to avoid an impact on the already strained city budget and taxpayers.

He stressed that a city contribution is required by state and federal agencies that have already committed to providing millions of dollars to the project.

No city contribution would mean no development, he said.

Preliminary figures show that by the end of the 25-year DIF plan, the project will add $1.9 million a year to city coffers. Over the 2 1/sub 2 decades of its existence, the plan is expected to create a total of at least $42.1 million in new revenue.

That's the money that city officials have to figure out how to split up and cover both city and project expenses.

If the 26 acres set for Phase I is left undeveloped, the city would garner only $4.1 million during the same time period, Milanoski said.