State transportation workers Tuesday scrambled to empty the swimming pool-sized hole that opened beneath MBTA tracks during the weekend rainstorm and will force thousands of commuters to rely on buses for another week or so.
‘‘Our goal is five to seven days, even if it’s a temporary fix,’’ said Michael Turcotte, director of systemwide maintenance and improvements for the Massachusetts Bay Transportation Authority. ‘‘That all depends on this water flowing...we have to wait till that’s done.’’
Even when full trolley service is restored, Turcotte said the MBTA may need to impose temporary speed restrictions in the Chestnut Hill area, where trolleys normally reach up to 40 miles per hour.
Passengers on the Green Line’s D-branch were shuttled on buses between the Newton Highlands and Reservoir stations, adding at least 20 to 30 minutes to most commutes.
Those caught unaware by the disruption were text-messaging friends to say they’d be late to appointments, and begging forgiveness from bosses. Many said they accepted the inconvenience as unavoidable, given that the four-day storm dumped more than 10 inches of water on the region.
‘‘As one of the drivers said yesterday, ‘For once, it wasn’t the T’s fault,’’ said Kyle Bozentko, a graduate student from Brighton who takes the T to a part-time job in Newton.
And Sean Staplefield, who was taking the D-branch as part of a commute home to Marlborough from downtown Boston, where he works as a cook, said, ‘‘It’s part of life. You’ve got to deal with public transportation. It’s either that, or pay $20 a day to park.’’
The D-Branch, also known as the Riverside Branch, carries about 23,000 people a day in each direction, and serves as an integral link between Boston and Newton. It also serves commuters who drive to Riverside from towns further west.
On Tuesday, 20 workers built makeshift dams, employed mechanical pumps, and unloaded gravel from specially equipped dump trucks that run on T tracks in an effort to divert and pump out the water that had rushed into the pit beneath the T tracks.
The sheer size and depth of the hole suggested there had been a powerful surge of downhill water, most likely coming from the nearby Webster Conservation Area. Turcotte said he plans to order 500 tons of ballast and earth to fill the 12-foot deep hole, which measured 50 feet across when it finally stopped expanding early Tuesday.
The T will also lay down boulder-sized rocks known as riprap to act as a retaining wall, and will install a 250-foot-long pipe to divert water permanently form the area.
The damage from the water did not stop with the MBTA’s breached trackbed. The mud, rocks, and dirt that were once holding up the trolley tracks continued to plunge downhill on Monday and Tuesday, landing in and around a 25,000 square-foot office building on Glen Road, pushing an 18-inch layer of fill across the entire first floor. Outside the building, the blob of mud and rocks reached as high as six feet, covering glass windows, and inside, the carpet was entirely covered with mud.
‘‘It’s all here,’’ said Mark MacNeill, chief operating officer of the group that owns the NormaTec building. ‘‘That’s a lot of earth moving.’’
Dan Green, a building owner who was surveying damage as tenants dragged out mud-covered computers and plodded through the parking lot with plastic trash bags around their legs, said ‘‘There’s a fundamental problem that that much water is flowing.’’
MBTA and city engineers from Newton are still researching the cause of the flooding. Bob Rooney, chief operating officer for Newton, said city officials are trying to determine whether a system of culverts intended to carry stormwater had failed. Rooney said it appears a nearby preservation area, which normally absorbs water that doesn’t make it into the culverts, was overwhelmed by the volume of water.
‘‘Typically, these systems are designed for the hundred-year storm,’’ Rooney said. ‘‘And I know we had a big one, but we want to make sure it was functioning correctly.’’
The damage is between the Chestnut Hill and Newton Centre stations, near Glen Avenue in Newton.
During Tuesday morning's commute, a fleet of eight T buses lined Walnut Street across from the Newton Highlands station as T workers ushered commuters onto the shuttle buses so they could catch a trolley at the Reservoir Station.
By the time the buses got to the Newton Centre station, many were packed. The crowd of commuters who gathered at the station waited about five minutes for the next round of buses to arrive.
“They are handling it pretty well,” said Anja Kuschpel, 25, of Newton. Kuschpel said she considered taking another shuttle but her Charlie Card kept her loyal to the Green line.
“As long as they are running, it doesn’t matter,” said Gerone Lockheart, a Boston University graduate student who was waiting at the Newton Centre station. “A shuttle is not a problem.”
Globe Staff Writer Lisa Kocian and Correspondent Caitlin Castello contributed to this report.