Safely Applying Treated Effluent to Land

In 2006, Sheri Simmons found a previously unknown bacterium in Salt Pond in Falmouth, Mass. There's a story in Oceanus, and you can read it here.

Last March, a watershed manager contacted Environmental Protection for information on programs that apply treated effluent from publicly owned treatment works (POTW) directly to land. I didn't have any answers then but have gotten more information now.

Rick Otis, who is the former deputy associate administrator of EPA's Office of Policy, Economics, and Innovation, recalled a case in Falmouth, Mass., a costal town on Cape Cod. The town needed to build a POTW and could not build an outfall to the ocean. "I think the Clean Water Act bans or at least limits new POTW ocean—as opposed to river—outflows," Otis explained. Instead, the community pumped treated effluent to the Massachusetts Military Reservation, formerly known as Otis Air Force Base.

The POTW sprayed effluent on open fields. Otis said: "I think the effluent had been treated to remove phosphorous but not nitrogen compounds. The result was a groundwater plume under the fields that contained nitrates. The plume carried the contaminated groundwater to local drinking water wells. The base also had groundwater contamination from old Superfund sites and land applied effluent from its own sewage treatment plant (USGS study, 1984).

"The lesson learned is that the effluent needs to be treated so that such contaminants don't end up contaminating drinking water sources," Otis added.

Judging by the date on the study, I would guess that any current programs would have serious nutrient removal technologies in place to prevent this type of contamination.

I plan to contact Idaho's Department of Environmental Quality where I hear facilities have been safely land applying wastewater for 20 years. I want to find out what technologies and practices are in place. Stay tuned.

–L.K. Williams

Posted by L.K. Williams, EPonline on Aug 04, 2009