Montgomery County Department of Environmental Protection officials said that the elevated levels of contaminants in the sediment being dredged in Lake Whetstone do not present health risks to residents.
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Montgomery County chose to dredge the lake because a significant amount of silt or sediments built up and caused a little island to form at the mouth where the stream comes in, Scott Gole, staff liaison for Montgomery Village Foundation Committee on the Environment, said.
The Montgomery Village Foundation owns Lake Whetstone.
Sediment buildup naturally occurs, Gole said. When it storms and rains, water moves at a velocity that erodes the side of the streams, picking up sediment, Gole said.
Biological, chemical and physical analyses were performed on the sediment before the dredging project was finalized, Kapenko said.
Elevated levels of polycyclic aromatic hydrocarbons, chemicals dangerous to animals that often appear in groups of two or more, were found in the sediment tested, Kapenko said.
Kapenko said the PAH are bound to the sediment chemically, and therefore it should not be of any risk to humans.
Even if humans, such as the laborers, did encounter the sediment, the PAH bound to it would be harmful only if digested in large quantities, Kapenko said.
Tests performed on the sediment revealed the presence of PAH, but Kapenko said they were bound to the sediment and is therefore not harmful to humans. Tests were not performed on the sediment when the lake was last dredged in 1986, Kapenko said.
According to the Environmental Protection Agency, PAH caused reproductive problems and birth defects in mice whose food contained a large amount of PAH. According to EPA, these effects have not been seen in humans. Damage to body fluids, skin and the immune system was also found in mice that consumed a large amount of PAH, according to EPA.
The contractors were aware of the levels of PAH in the sediment because the test results were included with the contract, Kapenko said.
Amy Stevens, manager of Stormwater Facilities Maintenance Program for the county, said it was residents who originally requested the dredging. Stevens said meetings were held prior to finalize the dredging design and to reveal the testing results.
Stevens said elevated levels of PAH were present in the sediment that was tested. The department determined after consulting with the Maryland Department of the Environment that the sediment could not be placed in a residential setting and that the sediment would have to be taken offsite, Stevens said.
According to the EPA, PAH can be transmitted through breathing, eating or drinking something contaminated with the group of chemicals.
Kapenko said neither the air nor the water in Lake Whetstone is contaminated with PAH and that only the sediment being dredged is contaminated.
Stevens said department members do not think that enough PAH would be released into the air to be a health concern for the residents. Stevens said that since the project should not increase the amount of PAH that may be in the air already, the dredging does not pose a risk to residents.
PAH comes from burning wood and coal products, Stevens said.
Stevens said the project was approved by the Maryland Department of Natural Resources. The project meets all noise ordinance requirements for the county, Stevens said.
People might hear the sounds of the dewatering equipment, trucks backing in and maybe dredging itself.
Commuters who drive on Montgomery Village Avenue probably noticed equipment floating in the lake.
The pipeline floating in the water “is not hooked up to anything,” Kapenko said.
Parties involved in the procedure will connect the equipment to the pipeline and run tests to make sure everything is watertight and in working condition by next week, Kapenko said.
As government requires, all involved parties gathered at the lake June 15 for a preconstruction meeting before the equipment was brought on site, Kapenko said.
Workers can begin grading and preparing the location only once they have received approval to move equipment to the site, Kapenko said.
The Montgomery Village Foundation is not paying for the dredging, Gole said.
Montgomery County will cover the cost because it assumed structural maintenance of Lake Whetstone and similar structures such as Lake Needwood and Gunners Lake in Germantown in 2005, Gole said. The foundation was responsible for the dredging in 1986, Gole said.
The county has chosen to begin the dredging after the great blue heron birds finish nesting, out of concern for wildlife.
Dredging will begin in Lake Whetstone at the end of this week.
Gene Kapenko, senior engineer and project manager for the procedure, said the mobilization of equipment is complete and that all of the equipment is now on site.
The total cost for the project is $2.84 million, Kapenko said. The company Mobile Dredging and Pluming Co. will dredge only the north and south portions of the lake, Kapenko said.
The sediment will temporarily be stored at Clean Earth in Upper Marlboro because that is the only facility that can store sediment containing hydrocarbons, Kapenko said.