Updated 5:15 p.m. Tuesday: Blasting in downtown Bethesda that’s required to help dig a 150-foot elevator shaft for a planned station on the Purple Line will now begin Monday at 9:30 a.m.
Crews will be blasting through hard rock every day at 9:30 a.m. until further notice. The construction will not occur on weekends or holidays, according to the website of the Purple Line Transit Partners, a public-private partnership that is building the light-rail line.
When completed, the Bethesda station will be the western terminus for the 16-mile, 21-station line, which will stretch as far as New Carrollton in Prince George’s County. The line is expected to open in late 2022.
Work has been ongoing on the planned Bethesda station, which will lie just above the existing Metro Red Line station at 7450 Wisconsin Ave. In the current phase, workers will dig a shaft that is 150 feet deep in order to connect the two train lines.
Blasting was originally scheduled to start this past Tuesday and occur between 5 a.m. and 8 p.m. However, Ken Hartman, director of the Bethesda-Chevy Chase Regional Services Center, said in an interview Tuesday that community members were concerned about a lack of information after receiving a notice Friday announcing that the blasting would begin.
Also, Hartman said the start of the blasting was delayed because Purple Line Transit Partners needed additional time to coordinate with the Washington Metropolitan Area Transit Authority (WMATA).
The information about WMATA came as a result of an email sent from Tim Cupples, the implementation manager with the Montgomery County Department of Transportation, to Purple Line Transit Partners outreach manager Carla Julian on Monday.
“Folks are asking for more specific information about the start time and what to expect. Am I correct in understanding that 5 AM is highly unlikely based on transit time to deliver charges and the prep work necessary?” Cupples wrote.
Julian replied by saying that Purple Line Transit Partners was still coordinating with WMATA.
“The preferred blasting time is 9:30 a.m. every day. If they miss that window for some reason, it would then be 1:30 p.m. People will hear the horn prior to blasting and then the actual blast lasts about 6 to 8 seconds. The blasting area will be covered with mats and a cover. Another notice for Monday will go out Friday and then we will notify at 9:30 a.m. each morning for the following day and so on,” Julian wrote.
Purple Line Transit Partners spokesman John Undeland said in an interview Tuesday that he wasn’t sure exactly how many days the blasting would take. During the periods when blasts are occurring, he said Red Line Metro trains would briefly stop outside of the Bethesda station for a period of five to 10 seconds. Passengers in the station, he said, may hear some noise but that it would be muffled by the mats covering the blasting area.
“They may hear some thumping and rumbling,” he said.
Undeland said that the six-to-eight second intervals are meant to minimize the noise and vibratory impacts from each of the blasts. The goal is to dislodge hard rock that cannot be moved by another method.
“Blasting is done in a very controlled method. No explosives are kept on-site. They’re brought in in the morning and taken out in the evening,” Undeland said.
In addition to the noise of the blasting, sirens will also sound to alert construction workers of when a blast is about to occur. Undeland said he wasn’t sure how loud the noise would be, but that it would “depend on where you are,” in relation to the construction site, which is on the 7200 block of Wisconsin Avenue.
Last month, a number of Silver Spring residents complained of being awakened at night due to noise from drilling occurring as part of the construction of a Purple Line tunnel in Silver Spring’s Long Branch neighborhood. After a group of residents visited Maryland Transportation Secretary Pete Rahn in his office to air their concerns, workers stopped drilling at night.
Undeland said he didn’t think the blasting would have the same side effects in Bethesda as it has in Silver Spring.
“It’s mostly a commercial area. Unlike other areas of the project, we’re not on top of folks’ homes to nearly the degree we are in Silver Spring,” Undeland said.
Undeland added that work on the Bethesda station needs to be done in “close coordination with WMATA.” He said he was not sure if the Bethesda construction would disrupt Metro service.
Dan Schere can be reached at Daniel.schere@moco360.media
