Carroll will study Piney Run Dam
County cites state concerns about emergency risks
Carroll County has launched what’s expected to be a two-year-long study to assess possible deficiencies in Piney Run Dam, provoked by concerns raised by the Maryland Department of the Environment.
The water of Piney Run Reservoir, in which local residents fish and boat, is held back by a 74-foot-tall earthen dam built in 1974, according to Chris Heyn, county watershed restoration engineer.
MDE, boosted by grant funding in 2016, inspected a number of dams across the state, including Carroll County’s dam at Piney Run, Heyn said.
“With changes to the climate and some failures of dams nationwide, MDE is evaluating dams around the state and recently expressed concern that the Piney Run Dam may not meet current criteria,” Heyn wrote in the environmental restoration quarterly newsletter for this fall.
Route 32 and t he Warfield Complex are downstream from the dam. The study will consider how possible changes to the dam would affect the surrounding area, according to Heyn.
“I wouldn’t anticipate any, but that’s why we have to do the study,” Heyn said.
Piney Run Dam is one of 93 high hazard dams in the state, according to MDE.
It is the only dam Carroll County owns that MDE classified as “high hazard,” according to Heyn.
“Failure of a high hazard dam would likely result in the loss of human life, extensive property damage to homes and other structures, or cause flooding of major highways such as state roads or interstates,” states an online MDE dam hazard classification fact sheet.
MDE officials expressed concern regarding Piney Run Dam’s emergency spillway capacity and tasked Carroll with analyzing the dam’s potential deficiencies, according to Heyn.
Upon learning of MDE’s concerns for Piney Run Dam, Carroll County began developing a request for proposals to have contractors look into the issue and, in the process, learned grant funding was available for the study, Heyn said. The county then shifted its focus to obtaining said grant funding.
Carroll County received a $500,000 grant from the Natural Resources Conservation Service in July, which will cover the cost of the study, Heyn said. National engineering firm AECOM, which has an office in Germantown, is conducting the study and AECOM staff had its kickoff meeting Friday with county staff, Heyn said.
The study is broken down into three phases, he said. In the first phase, AECOM will conduct field investigations that involve examining existing conditions such as sediment, soil, rock and erosion. Next, AECOM will evaluate options to address any deficiencies it might find, and the final phase will be the writing of the final report.
MDE will be kept up to date, and a draft report will be shared with the department so it can offer feedback along the way to the study’s completion, Heyn said.
The dam’s emergency spillway is designed to hold 27 inches of rain over a period of six hours, and the closest Carroll County has come to experiencing that level of precipitation was shortly after the dam was built, according to Heyn. In 1975, Hurricane Eloise dumped a little more than 14 inches of rain over a few days, he said.
“Twenty-seven inches in six hours is the largest anticipated storm that could ever happen in our area,” Heyn said.
He wrote in the environmental restoration newsletter it is “unlikely” Carroll would experience a storm of this size, but the county sided with MDE’s stance of prioritizing public safety and moved forward with starting a study.
Heyn said MDE inspects the dam annually.
There are “hundreds” of low-hazard dams throughout the county, as well as one significant hazard dam on a pond by the Carroll County Farm Museum and Agriculture Center, Heyn said.
There will be a public meeting after the first phase of the Piney Run watershed study is complete, which is expected to be in January or February, according to Heyn. Residents will be invited to offer comments on the study, he said. The date and time of the meeting will be publicized closer to then.