The excavation of the Cascade Lake Dam that began Monday morning could take several days to complete, part of a project to reduce the risk of flooding from the damaged earth-and-stone dam.
Lt. Walter Dayton of the Carroll County Sheriff’s Office confirmed that work as ongoing Tuesday and, as of 5 p.m., there had been no issues.
Workers have been pumping water from the lake into the east branch of the Patapsco River since last week, lowering water levels in preparation for a controlled breach of the dam.
“The water is not being removed through the breach in the dam, which is in the top 8 feet of the dam, but through the continued pumping,” Maryland Department of the Environment Secretary Ben Grumbles said. “The breaching of the dam will continue and it will take several more days before the dam removal is completed.”
“They’re actually just going to cut the dam level out from the top down to the current water level,” Tim Brown, the Carroll County Sheriff’s Office’s public information officer, said 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.”
During the excavation of the dam, a hazard of dam failure still remains, according to a Facebook post from the Carroll County Department of Public Safety. With the possibility of dam failure, the county is warning area residents to be advised and remain vigilant and aware.
“So far, things are going well with the excavation,” Brown said. “Now there is still a possibility, because of the damage that pre-existed, 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.”
A controlled breach had been planned to take place Saturday, after pumping had significantly lowered the water level in the lake, but heavy overnight rains on Friday refilled the lake and further damaged the dam.
“What’s amazing to me, we were up there before the rain that was on Friday and how low the lake was at that time. It was well down below the dam. The slides coming down, there was no water there, you would hit the mud,” said Carroll County Commissioner Dennis Frazier, R-District 3, who visited the lake Friday, Saturday and again on Monday. “When I went back after the rain came, the water was up into the bottom of those slides. That’s how much it had risen up. It was unbelievable.”
With the possibility of dam failure present, the county is warning area residents to remain vigilant and aware.
As pumping continues while the excavation process occurs, it’s possible that residents downstream might not notice any “significant effects” due to the breach, but increased water levels could 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 such as 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 it was in the middle of last week, allowing excavation to begin Monday morning. He said that if more rain comes, the water will flow downstream as opposed to being held 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 by the MDE’s Division of Dam Safety, according to the county.
“We extended our notification to the dam owner to ensure that the work was completed by Aug. 13,” Grumbles said. “Initially we had stated that it had to be completed by Aug. 6.”
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 situation has been addressed. Plans have been made to close roads if necessary.
This situation is dynamic, and additional updates will be distributed via Twitter and Facebook from the Carroll County Sheriff’s Office as warranted.
MDE is responsible for ensuring the safety and maintenance of dams throughout the state through the Division of Dam Safety.
After heavy rains overnight Friday filled Cascade Lake to the brim by Saturday morning, Carroll County officials cautioned that an uncontrolled breach of the lake’s dam, and thus further flooding, was possible.
Dams are categorized as either high hazard, significant hazard or low hazard, and are inspected accordingly — annually for high hazard, every three years for significant hazard and every five to seven years for low hazard, according to the MDE website.
Cascade Lake dam was listed in the significant hazard category, MDE Communications Director Mark Shaffer confirmed Tuesday.
Earthen dams, of the type at Cascade Lake, are the most common type of dam in the state, according to the website.
Grumbles could not say whether the Cascade Lake Dam had been inspected recently— “I don’t know the status of the dam prior to the storm,” he said — but did say there was an emergency action plan in place, a requirement for high and significant hazard dams due to legislation signed by Gov. Larry Hogan.
What Grumbles could say was that he believes the severe weather had a significant impact on the dam.
“I don’t have all the technical information and facts from my staff, but what I can say without a doubt is this extremely heavy rainfall that we’ve been getting was really the straw to break the camel’s back,” he said. “This is an example of climate adaptation and resiliency ... of critical infrastructure that can be at risk due to increasingly wet weather and extreme weather events.”
As for the future of Cascade Lake, Grumbles said there is a permitting and environmental analysis process should the owners wish to build a new dam, but noted that it is a big undertaking.
“Today, constructing a dam and getting it permitted and doing all the environmental analysis amounts to considerable amounts of time and efforts,” he said. “There’s a lot of important environmental requirements and regulations that come into play when you are constructing a new facility like a dam.”
“What kind of grants or money could we get from the state or federal government? I don’t know. We haven’t looked into it yet,” he said. “But we would certainly be interested in helping out the owners of that property, as we would any other business that has a catastrophic event happen to them.”
And should the owners decide they don’t wish to rebuild? Frazier said people have already been making suggestions to him, including the idea that the county could take the property over as a park.