The excavation of Cascade Lake dam began Monday morning and may take several days to complete.
“What’s happening ... is the breach of the dam itself. So they’re not just going to actually cut a hole and have all the water flow downstream. They’re actually just going to cut the dam level out from the top down to the current water level. They’re going to continue to pump out,” said Tim Brown, the Carroll County Sheriff’s Office’s public information officer, on Monday. “And once the lake is a little bit lower, they’re going to come back in and they’re going to excavate more and keep taking that down until they get to a level that [the Maryland Department of the Environment] has said is where they want it to stop.”
Water will be released downstream at the same rate that has been occurring over the past several days, according to a news release from the sheriff’s office.
“So far, things are going well with the excavation,” Brown said. “Now there is still a possibility, because of the damage that preexisted, that the dam could still fail. However, the volume of water has been reduced greatly because of all the pumping that’s going on and that’s continuing.”
As pumping operations continue as the excavation process occurs, it’s possible that residents downstream may not notice any “significant effects” due to the breach, but increased water levels may still occur as the work progresses, according to the county.
If the dam fails and an uncontrolled breach occurs, areas downstream of Cascade Lake along the Tributary of the East Branch of the Patapsco River should be prepared for large amounts of water flowing downstream and possible flooding, according to the Sheriff’s Office. Affected areas include locations south of Cascade Lake including Snydersburg Road, Hampstead Mexico Road and Brodbeck Road.
Brown said continued rain has hindered the process, but though precipitation set the process back some, the lake’s water level is back down to where is was in the middle of last week, which allowed them to begin excavation Monday morning. He said if more rain comes, the water will flow downstream as opposed to being held because in the dam because of the excavation and controlled breaching.
“It can’t hold nearly the water that it could before,” Brown said.
Excavation operations at the dam are being monitored by the property owner’s engineers, and also by the MDE’s Division of Dam Safety, according to the county.
Snydersburg Road in the area of the dam, between Cape Horn Road and Hampstead Mexico Road (Md. 482), remains closed, and the closure will last until the emergency condition has been addressed. Plans have been made to close roads if necessary.