The huge, ongoing sewage spill into the Merrimack River in Haverhill, Mass., definitely won’t flow 75 miles upstream to Concord, but officials are watching to see if any will drift four miles to Seabrook beaches after reaching the ocean.
The New Hampshire Department of Environmental Services said it has increased testing of New Hampshire coastal beaches to see if the fecal flotsam will have effects here. The NHDES Healthy Swimming Mapper lists the most recent findings of the tests.
For context, the spill is sending up to 10 million gallons of raw sewage into the river daily, which is enough to fill 15 Olympic-size swimming pools.
However, somewhere around 5 billion gallons of water flows out of the Merrimack River at its mouth every day, depending on the time of year. The Haverhill sewage release is about two-tenths of 1% of that total.
Tests of the Merrimack River itself below Haverhill have shown very high counts of the E. Coli bacteria, including one site (Ferry Park in West Newbury) registering 40 times the safety limit. People are being encouraged to stay out of the River at least through the July 4th weekend, and several beaches in Massachusetts near the river’s mouth have been closed.
It is not uncommon for large amounts of sewage to spill into the Merrimack River for a short period after a big rainstorm overwhelms a city’s wastewater treatment system. The current outbreak in Haverhill is very unusual, however, because two broken pipes mean that raw sewage undiluted by rainwater is continuing to pour into the river for days on end.
“It’s hard to compare” to other spills because “this is pure sewage, 10 million gallons, and it’s ongoing,” said Curt Rogers, executive director of the Merrimack River Watershed Council. “We don’t know what happens when it continues day after day after day, and the compounding impact.”
The release happened, according to the city of Haverill, when a 42-inch line that carries most of the city’s wastewater from the main pumping station to the treatment plant broke after heavy storm June 27. Haverhill is one of the cities on the Merrimack which has combined sewer outflow, or CSO, meaning that rainwater drains into the same pipes which carry sewage. That situation can lead to overflows in heavy storms.
Haverhill, like Manchester, is in the process of separating the two systems.
Concord has had two separate systems — one carrying rainwater, one carrying sewage — since the 1970s, when it built the current system, said Marco Philippon, deputy manager of Concord’s General Services department.
Philippon said rainwater sometimes does enter the sewer system, through newer drains or cracks in old pipes. That process, known as infiltration, is being measured by meters as part of updating the wastewater collection system master plan, he said.
“It takes a pulse of the health of our system, including infiltration. We do not see much infiltration at all,” he said.
