What happens when tens of thousands of gallons of water are poured on top of a landfill?
That’s exactly what happens every time it rains on the Dewey Daggett Landfill, an old dump site sitting inside Rumney Marsh.
When an inch and a half of rain fall here, just as it did during the recent nor'easter, more than 50,000 gallons of water hit the surface. There’s no real cap.. just about a foot of soil and grass covering more than 20 feet of buried waste from mid-century Saugus and Revere.
Dewey Daggett Landfill -- Rumney Marsh, Saugus
Images via Massachusetts EEA / MassDEP (Dewey Daggett Landfill Shoreline Restoration, 2022)
Here’s where that rain goes:
Infiltration
The thin soil layer slows the water, but can’t stop it. Rain seeps downward through sand and fill, then into layers of buried debris.
Percolation through waste
Below that surface is a jumble of household garbage, ash from local incinerators, industrial cast-offs, demolition rubble, and even oily rags and metals... the kind of mixed municipal waste common before environmental laws existed. As water moves through it, it becomes a dark, chemical-rich liquid called leachate. It's like brewing coffee, but with World War II era waste.
Lateral seepage
Because the landfill sits directly in a tidal wetland, this contaminated water doesn’t stay contained. It moves sideways through the saturated layers, following the natural groundwater gradient, oozing toward the salt marsh, creeks, and the Pines River.
Diffuse discharge
Instead of a single pipe, it seeps out everywhere: tiny seeps along the riprap, small trickles through mud, and invisible groundwater flow beneath the marsh surface. With every tide, that contaminated porewater mixes into the ecosystem that supports fish, crabs, and migratory birds.
So when it rains, it’s not just “runoff.” It’s an invisible exchange.. stormwater in, polluted water out.
The recent shoreline stabilization project was an important start, reinforcing the eroding bank and preventing waste from washing out directly. But it doesn’t address what’s happening from above and within.
A true solution would mean a full engineered cap; multiple layers that shed rain, seal waste, and stop leachate from forming at all.
Rumney Marsh deserves more than erosion control. It deserves clean water from the top down.
