This artist’s rendering depicts Trinity Financial’s planned $500 million development along the Hamilton Canal District in Lowell.

A Boston-based developer has been given the green light for a $500 million transit-oriented project that could remake downtown Lowell.

Following months of deliberations, the Lowell City Council has selected Trinity Financial to turn an underused 15-acre waterfront site into a neighborhood with apartments and condominiums, shops, offices and a $100 million courthouse near the city’s commuter rail station.

“Our vision presented a startling difference compared to the competing submissions,” said James Keefe, a Trinity principal. “The site offers opportunities and challenges. But now we can commence a comprehensive public approval and permitting process and at the end of it we will have a definitive sense of what the community wants.”

The area, dubbed the Hamilton Canal District, consists of several vacant buildings within walking distance of City Hall bounded by Jackson, Appleton and Middlesex streets. The Hamilton, Western, Merrimack and Pawtucket canals have the potential to form a grand waterfront backdrop for the retail and residential development, officials said. It could be the most ambitious redevelopment plan Lowell has undertaken since the Industrial Revolution, they added

Last year, the city issued a Request for Proposals and received submissions from seven developers. In February, two others in addition to Trinity were selected as finalists: Struever Brothers Eccles & Rouse of Baltimore, and the team of New York-based Leyland Alliance and Cornish Assoc. in Providence, R.I.

While Struever hired former Massachusetts Senate President Robert E. Travaglini to make its case to Lowell officials, and Alliance and Cornish asked Thaleia Schlesinger – twin sister of Paul Tsongas, the late U.S. senator and Lowell native – to lobby on their behalf, the council chose Trinity.

“Trinity presented the most complete and well-rounded response to the solicitation and demonstrated the best breadth of experience and skills related to all of the different components of this project,” Lowell City Manager Bernard Lynch said in a prepared statement. “They clearly demonstrated multiple successful examples of highly complex and difficult public-private mixed-use development projects in Massachusetts that represent all aspects of the proposed Hamilton Canal District project.”

‘Really Excited’

Trinity has earned praise for a variety of projects in its 20-year history. The company recently celebrated the opening of Maverick Landing, a mixed-income housing community located on East Boston’s waterfront. The $34 million HOPE VI development replaced Maverick Gardens, a deteriorated public housing development, with 396 units in 20 townhouses and six mid-rise buildings.

Another Trinity project, recently approved by the Boston Redevelopment Authority, is Avenier, a 10-story, mixed-use, transportation-oriented development that includes retail on the ground floor and 241 residential units. It is located in the Bulfinch Triangle near North Station.

Lowell’s project would be located along three canals near the Gallagher Terminal, Lowell’s commuter rail station. The project will consist of more than 1 million square feet of commercial, retail and office space, and up to 1,000 apartments and condominiums. Construction could begin as early as 2008

The RFP asked developers to devise a plan that includes a mix of commercial space – including small and large retail, as well as office space – and waterfront residential units. It also calls for the creation of a pedestrian link from the MBTA to the downtown and active first-floor uses, in addition to sidewalks, trees and lighting.

Trinity proposed a mixed-use development with a supermarket as an anchor, market-rate housing, the judicial center, public open spaces and a parking garage.

Lowell, the fourth-largest city in Massachusetts, is located at the intersections of Interstate 495, Route 3 and Interstate 93. During the 19th century it was a thriving industrial center, attracting immigrants and migrant workers. The city’s story is one of textile mills that were built around the Merrimac River.

But the companies began to shutter in the 1920s and the last ones closed in the 1950s. In the mid-1970s, Tsongas convinced local banks to provide low-interest loans to finance the preservation of historic buildings. Those efforts played a major role in spurring a revitalization and historic preservation of its 19th century brick mills.

Over the past 30 years, Lowell’s downtown has gone from boarded-up vacant buildings to businesses that are luring shoppers. Revival efforts since the 1980s have helped attract people to the downtown, helping to transform it from a center of industry to an urban village.

The rehabilitated mill buildings are complemented by nearly 3 miles of trolley and canal boat tours and several museums. Major initiatives such as the Lowell National Historic Park, the Tsongas Arena and the redevelopment of mill buildings into loft-style condominiums have helped boost the modest retail district.

Still, like many of the state’s older urban centers, Lowell has its problems. Its Massachusetts Comprehensive Assessment System scores are near the bottom. Last year, sixth graders placed 297th out of 308 Bay State school districts in English while student math scores ranked 298th. In addition, the city’s violent-crime rate in 2005 for rape and aggravated assaults exceeded Cambridge, a comparably sized city, according to the Massachusetts State Police.

Home prices have slipped in Lowell to their lowest levels in nearly four years. The median price for a single-family home fell to $230,000 during the first seven months of 2007, down from $256,250 for the same period last year – a 10.2 percent drop – according to statistics from The Warren Group, parent company of Banker & Tradesman.

Nevertheless, Trinity’s Keefe said the Hamilton project could spur development, making the city more attractive to buyers who are priced out of Boston.

“We’re really excited about putting together a New Urbanist style of development that will really feel like it is really part of the city and at the same time honor the city’s past and future,” he said.