BANGOR, Maine — For the past two years, it hasn’t looked like much was happening at the Margaret Chase Smith Federal Building on Harlow Street, despite the allocation of $53 million in stimulus money for major renovations.

Today, the 44-year-old building is surrounded by scaffolding, and workers clad in hard hats can be seen scurrying in and around the building day and night.

The project is 65 percent complete, on budget, and is expected to be finished in September 2013, about three months ahead of schedule, according to Patrick J. Sclafani, public affairs officer, congressional and intergovernmental affairs, for the General Services Administration’s New England region in Boston.

The cost of construction is estimated at $33.88 million with the remaining money going toward design services, according to the GSA, which oversees federal facilities.

The GSA estimated in 2010 that nearly 300 people would be employed at times on different aspects of the project. Sclafani said that as of Friday, 382 people have been employed during some phase of the project.

“The vast majority of employees contracted under the project have been Maine residents,” Sclafani said in an email. “An average of 75 trade workers currently are on-site each day in addition to the numerous vendors, inspectors, engineers, service companies and management personnel.”

A majority of the upgrades to the building are being implemented to improve energy efficiency, Sclafani said earlier this week.

Systems designed to reduce water consumption by 40 percent and energy use by 30 percent are expected to be completed in September. In addition to the geothermal heating and cooling system, advanced heating, cooling and lighting controls are being installed. The old underground oil tanks have been removed and natural gas lines have been connected to the building.

The building also will be made compliant with the Americans With Disabilities Act through renovations to public restrooms and the front plaza slope and the proper placement of elevator controls and door hardware. An additional elevator also has been installed.

“A lot of this job isn’t very exciting,” Gianne P. Conard, regional chief architect and regional recovery executive for the GSA in Boston, said Thursday on a construction tour. “This building is more than 40 years old. It needed to have its systems completely replaced.”

Work on the project began in September 2010.

The federal building houses the U.S. District Court, U.S. attorney’s office, U.S. Bankruptcy Court, U.S. Marshals Service, U.S. Probation and Pre-trial Services, Social Security Administration, Federal Bureau of Investigation and offices for other federal agencies. U.S. Sens. Olympia Snowe and Susan Collins both have field offices on the second floor.

Most of the work on the building takes place from 5:30 p.m. to 3:30 a.m. Monday through Friday, according to Sclafani.

The biggest challenge, he said, is working in an occupied building, which is heavily used by the public, with the least possible disruption.

“We have had very little impact in our office from the construction,” Carol Woodcock, who works in Collins’ office, said Thursday. “The most important thing we do is constituent services. We really aren’t bothered by it.”

Collins’ office, however, temporarily will move next month to a smaller space in the building while the ceiling tiles, lights and windows are replaced. That work, which includes asbestos abatement of old ceiling material, appears to temporarily have displaced other tenants in the building.

All tenants have been able to remain in the building during the renovations, according to the GSA.

Conard declined Thursday to discuss how much asbestos was in the building, whether a majority of the ceiling tiles contained asbestos or if the cancer-causing substance was found elsewhere in the building. She referred questions to Sclafani.

“There is no health risk to tenants at the Margaret Chase Smith Federal Building and Courthouse, and the entire restoration project has complied with abatement standards,” Sclafani said in an email Friday. “No one has been exposed to hazardous materials as a result of the work conducted by GSA or its contractors at the site.”

Sclafani added: “A hazardous material survey for the building conducted in November 2009 did reveal that the ceiling tiles in Senator Collins’ office contain asbestos, and therefore all employees in that office will be temporarily relocated while the tiles are being removed as the restoration project continues.”

Air quality tests have been taken since the project began, according to the GSA.

“Consistent with major renovation projects of occupied buildings, GSA performs necessary air-quality testing,” Sclafani said earlier this week in an email response to questions about the project. “At the [federal] building, GSA has performed random air-quality tests every other week for the duration of the major demolition work, and the reports were consistently clean. Whenever a specific concern has been expressed — there have been a total of five over the course of the project — we have responded by testing the area in question and working with the tenants to address their concerns.

“Responses have included not only air testing, but also creating additional containment, providing additional filters, performing additional cleaning, and providing a detailed work schedule to inform tenants when work will take place in their areas,” he continued. “Air tests have consistently demonstrated that the work meets or exceeds the standards set by [the U.S. Environmental Protection Agency].”

While most of the renovations to the building won’t be visible from the sidewalk, major changes to the entry and lobby area will give the building a face-lift. Instead of two entrances at either end of the building, there will be one entry at the center.

The lobby, located at the front of the building where the post office boxes were for more than four decades, will include a large portrait on glass of Sen. Margaret Chase Smith, for whom the building is named, Conard said Thursday. Offices for the Social Security Administration will be relocated from the second floor to larger quarters on the first floor where the post office used to be.

The post office moved to the former Bangor District Court building on Hammond Street in October 2010.

“SSA needs to be easily accessible to the public,” Conard said. “The more accessible it is, the better it is for everyone.”

In a statement Friday afternoon, Snowe cited stimulus projects, including the renovations at the federal building, that have provided temporary economic benefits for Maine, but she faulted the Obama administration and Congress for failing to “to foster policies to help restore the right environment enabling businesses to create jobs.”

She added: “In projects across the country — including the infusion of $25 million for broadband and fiber-optic expansion in Maine, the rehabilitation of a stretch of highway on I-295 from Brunswick to Gardiner, $35 million to extend the Downeaster passenger rail service from Portland to Freeport and Brunswick, and renovations [at] the Margaret Chase Smith Federal Building in Bangor with over 300 new jobs — temporary jobs certainly were created for vital projects in our state, but it is absolutely imperative that Washington put partisan politics aside to instill confidence and certainty in the long term so that businesses can appropriately plan for their future, create additional jobs, and contribute to the growth of the overall economy.”

While the project at the federal building in Bangor is on budget, any unused money allocated for it would not remain in Maine but would be returned to the GSA’s Central Offices in Washington for redistribution to other projects funded by the American Recovery and Reinvestment Act, according to the GSA.

Fast facts

The planned renovations to the Margaret Chase Smith Federal Building include:

• New mechanical, electrical, lighting and plumbing systems, including high-performance green building components.

• New life safety systems, including sprinklers and fire alarm systems.

• New and renovated elevators.

• New energy-efficient windows.

• New telecommunications systems.

• Tenant space improvements and renovations to vacant spaces for occupancy.

• A new entry pavilion and security screening area.

• Building security upgrades.

• Site and plaza improvements.

• Accessibility upgrades.

• Relocation of the Social Security Administration’s office from the second to the first floor.