Whetstone Contaminants Test Too High

With sediment samples showing three kinds of elevated contamination, county officials say they will not dump the tons of silt that will someday be dredged from Lake Whetstone at any of three Montgomery Village sites that were being considered—or near any neighborhood anywhere in Montgomery County.

The findings have left the Montgomery County Department of Environmental Protection without a plan for handling the roughly 10,000 cubic yards of sediment that will be pulled out of the lake, but officials are vowing to follow through on the $750,000 project, the largest and most expensive dredging the county has ever attempted.

DEP got the report results last week. Three sediment samples taken from the 26-acre manmade lake show:

• ”Elevated” levels of five kinds of Polycyclic Aromatic Hydrocarbons. Considered a carcinogen, excess PAH on its own prevents the county from disposing of the sediment in a residential setting.
• Heavy metals also tested high, though the three lake samples weren’t dissimilar from a background sample taken from Apple Ridge ballfield
• Heightened levels of fecal coliform bacteria, though the sampling was inconclusive as to its day-to-day presence, according to DEP. An abundance of the bacteria is a sign of sewage contamination, according to state officials.

DEP is conferring with the Maryland Department of the Environment and the U.S. Army Corps of Engineers, and will get a better grasp of the extent and significance of the contamination.

“We’ll be working with MDE and the Army Corps to determine and identify other management options, but that’s enough for us to say we’re not going to put it in any residential area,” said DEP director Bob Hoyt.

The project’s timeline had called for dredging to start sometime in 2013 or later. DEP hasn’t determined whether the timeline will now slow down or the costs mushroom, Hoyt said.

Lake Whetstone—built in the 1960s to function as a massive stormwater management pond—hasn’t been dredged since 1986. So much silt has since piled up that broad, vegetated sandbars rise out of the water at its southeastern end.

DEP had been looking at three sites for disposing the sediment, all owned by the Montgomery Village Foundation: Apple Ridge ballpark, Apple Ridge recreation area (the soccer field behind Apple Ridge pool) and the lower of the two fields behind the Montgomery Village Foundation’s office on Apple Ridge Road.

The prospect of tons of contaminated sediment being dumped nearby alarmed neighbors to those sites this summer. In response to the outcry, DEP agreed to test the sediment—a step the county has never been required to take in any prior dredging project, Hoyt said.

Given Lake Whetstone’s size and the volume of runoff it handles, DEP had expected to find excess chemicals—just not this much.

“This is a huge lake … so when it captures all that runoff, it may not be so surprising that a lake that big would have the kind of contamination that we’re finding,” Hoyt said. “These stormwater facilities are meant to capture contaminants. The fact that there’s contamination in there doesn’t surprise us. But it’s the levels—.”

The experience with Lake Whetstone has compelled DEP to test sediment prior to all future dredgings.

“We will be establishing protocols to deal with this,” Hoyt said. “It’s the right thing to do.”

County officials will explain the findings—and their impacts on the project—in greater detail at a forum on Tuesday night, from 7 p.m. to 8:30 p.m. in Watkins Mill High School’s cafeteria. After DEP’s presentation, the meeting will open to questions from the community.