ANNAPOLIS – The potential for terrorist attacks has Maryland water authorities rethinking their use of potentially risky chlorine for disinfection and seeking alternative ways to make water safe.
“It’s a gas that asphyxiates and kills very quickly, so it’s a very hazardous gas to deal with,” said Stephen Gerwin, operations support manager for the Washington Suburban Sanitary Commission.
The chemical, he said, was even employed as a weapon during World War I. Consequently, stockpiles of chlorine, used to effectively treat water for about a century, need to be examined, Gerwin said.
“We need to take a harder look at the storage of chlorine . . . it’s a different world now.”
Aside from reviewing ways to better store the chemical, state water treatment plants have zeroed in on disinfection alternatives such as ultraviolet light, sodium hypochlorite (bleach) and ozone. However, each alternative has a catch: Ultraviolet light is safer, but very expensive; sodium hypochlorite is also safer, but takes up too much space; ozone is less toxic, but highly explosive and difficult to monitor.
WSSC, which serves 1.6 million residents in Montgomery and Prince George’s counties, tested ultraviolet disinfection at one plant and now plans to convert three other wastewater treatment plants to that method within four years at a cost of $2 million per plant, Gerwin said.
“We’re trying to make investments to reduce risks,” he said.
The Bureau of Water and Wastewater, which provides water to 1.8 million people around Baltimore, has converted one plant and will convert its other two water filtration plants to bleach disinfection, said Ralph Cullison, BWW chief of environmental services.
“There’s less concern handling it,” he said. “It’s proven to be pretty workable.” The conversion was made for the sake of security.
But plant officials aren’t the only ones taking a closer look at chlorine. Since May, a joint committee called the Water Security and Wastewater Systems Advisory Council/Interagency Technical Assistance Committee on Wastewater Treatment Systems has been drafting a report on water treatment plant reforms, to be presented to the General Assembly in December.
“The problem with gaseous chlorine is that it’s volatile,” said Virginia Kearney, deputy director of the state Water Management Administration and committee member. “It can be harmful to public health and that is why we want to at least look at other options.”
All but one of the 500 community drinking water systems in the state now use some form of chlorine, the committee found.
More than $5 billion is needed over the next 20 years for overall water plant improvements, the joint committee determined, up from the $4.3 billion recommended by a 2001 task force. That figure does not even factor in chlorine alternatives. The committee estimated the cost of converting all the systems in Maryland to ultraviolet disinfection at $75 million.
The key issue at hand, said C. Victoria Woodward, co-chairwoman of the joint committee, is environmental responsibility. “That goes down to quality of life and health and safety,” she said. “We are here not just to protect ourselves, but to protect our future.”