Efforts at cleaning up groundwater contamination on Joint Base Cape Cod have been proving successful. However, a portion of the base, highly contaminated from munitions and fireworks use, could take more than two decades to clean up.
That was the advisory offered to the Bourne Board of Selectmen during its meeting last Tuesday, August 17. Benjamin P. Gregson, remediation manager for the Army National Guard’s Impact Area/Groundwater Study Program, spoke to the board about efforts underway to mitigate what he referred to as “plumes” of contamination in several areas of the base.
Mr. Gregson said the largest plume of contamination is in the northern portion of JBCC, called the central impact area. He explained that the high amount of contamination results from “years and years of artillery firing that occurred on base, targeting the central impact area, right in the middle of the base.”
There are two main contaminants the groundwater study program is dealing with, Mr. Gregson said. First, there is RDX, which stands for Royal Demolition Explosive, a component of military explosives. In addition, there is perchlorate, an ingredient used in rocket propellant that is also used in commercial fireworks, he said.
Groundwater in that plume, he said, is moving in a northwesterly direction, toward the Cape Cod Canal.
Approximately eight years ago, a pump-and-treat system was installed, Mr. Gregson said, with two wells in the center of the plume. A third well was positioned to catch any contamination before it wound up off-base and in the Town of Bourne, he said.
With all three in place, he said, “we have the final remedies in place for that plume,” and it is being cleaned up. However, it is the largest plume and will take the longest amount of time to clean up, he admitted.
“It’s going to take us 20 to 25 years before we reach the cleanup level on that particular plume,” he said.
Mr. Gregson said there are approximately 17 technicians on the base this summer working in the central impact area. Crews are removing unexploded munitions that could be a potential future source of groundwater contamination, he said.
“We have the teams in place to take care of those items and to remove them and to dispose of them safely, both from a safety standpoint and an environmental standpoint,” he said.
Mr. Gregson said the cleanup program was started in 1997. It was initiated by administrative orders issued by the US Environmental Protection Agency. He said he has been working on the cleanup program since 1999.
Other areas with plumes impacting the Town of Bourne, he said, include the western side of the base as well as to the south, near the Otis Rotary. Also, Monument Beach and a small portion of land north of the town landfill. He assured the board members that his program is “not just cleaning up the base.”
“Since 2004, the program has had groundwater treatment systems in place to pump and treat the groundwater,” he said. “That has had a result of both shrinking the size of the plumes and decreasing the concentration of contaminants in the plumes.”
He pointed to a southern portion of a map of the base called Demolition Area 1. That particular area, he said, is where training with demolitions and explosives took place. It was also where law enforcement agencies, such as Massachusetts State Police, would destroy confiscated fireworks, he said.
Selectwoman Judith M. Froman asked how long fireworks displays took place at that site, and Mr. Gregson said it lasted six to eight years. Contamination from the demolition, he said, was first detected around 2006.
Ms. Froman asked if groundwater contamination from fireworks should be a concern for other locations, and Mr. Gregson said absolutely. He noted that many fireworks displays are done over the ocean, so it is not as big a concern. The situation on the base, he said, was the repetitive nature of the activity.
“Year after year, and with the prevailing winds that time of year,” he said, “the smoke and debris always landed in the same spot, on the high ground in the northern part of the base, so there was just a concentration of that smoke and debris from the fireworks.”
Those activities were discontinued, but they resulted in a contaminant plume of RDX and perchlorate. The contamination migrated from the base to the west and crossed over into Bourne, just north of the Otis Rotary, he said.
Treatment systems were installed, the first one in 2004, he said, and since then the level of contamination in that plume has dropped significantly.
“The maximum level of perchlorate, off-base now, as a part of that plume in the Town of Bourne is now at 2.7 parts per billion,” he said. “That’s just above the state drinking water standard of 2, so levels have been coming down successfully.”
Board chairman Peter J. Meier asked Mr. Gregson about the likelihood of federal resources drying up relative to the project. Mr. Gregson said that was unlikely given the program is acting under orders from the EPA. The program is also under scrutiny by the Massachusetts Department of Environmental Protection, he said.
“So there’s a regulatory hammer for us to continue to do this work or be subject to fines and penalties if the EPA’s not happy with the way things are going,” he said.