This story was updated at 4:05 p.m. Aug. 10, 2021, to correct the start date of the project. Montgomery County provided the incorrect date in a press release.

Pepco’s work on a new substation on Randolph Road in the Rockville area — starting Aug. 30 — will significantly affect traffic there for at least the rest of the year, according to the Montgomery County Department of Transportation.

In a press release, the county urges travelers to find alternate routes because of “major traffic disruptions that will last through early 2022.”

The county estimates that construction will take six months, but it could go longer if there are delays from weather or other factors.

The work will extend on Randolph Road from Parklawn Drive to Nebel Street.

Traffic headed west on Randolph Road will be detoured to Parklawn Drive, then to Md. 355.

Sidewalks will stay open throughout construction, the county DOT press release says.

The press release says a subcontractor for Pepco will excavate “a 27-foot x 40-foot entry pit for a microtunnel operation” that’s part of the substation construction

The subcontractor will then create two microtunnels that will go under the nearby CSX railroad tracks.

The DOT’s press release that was emailed on Friday said the work will start on Aug. 9. However, Pepco already had announced by then that it changed the start date, Sean Matthews, a senior communications specialist for Pepco Holdings, said Tuesday.

Matthews said the new start date is Aug. 30.

Emily DeTitta of Montgomery County DOT said Tuesday that the county heard from Pepco on Saturday about the error.

The DOT told the county’s communications office, which removed the press release from the county’s website, she said. However, the county did not send a follow-up email noting the date change to those who received the press release.