Heavy rains cause headache for East Bay sewer treatment plant officials in East Bay

Eric Thomas Image
ByEric Thomas KGO logo
Friday, January 17, 2020
Heavy rains cause headache for sewer treatment plant officials in Concord
Heavy rains caused East Bay Municipal Utility District officials to open the Pt. Isabel facility in Richmond to divert excess water flow and prevent mixed stormwater and untreated sewer water from spewing into the bay.

CONCORD, Calif. (KGO) -- Thursday's heavy rains in the East Bay caused headaches for sewer treatment managers trying to handle a huge increase in water flows.

It's the rain effect you can't see that keeps East Bay Municipal Utility District (MUD) officials up at night.

RELATED: Storm brings heavy rain, flooding to Bay Area

The same rainwater that fills local reservoirs can get mixed in with untreated sewage, and under the right circumstances, end up in the bay untreated.

"The rain is coming into the sewer pipes of the cities and makes its way to our interceptors," says Eileen White, a wastewater treatment manager for the East Bay Municipal Utility District, standing in front of a bank of computers that keep track of water flows.

"Yesterday at this time when it wasn't raining, our flows were about 50-million gallons per day," she says.

RELATED: Fact check: Here's what actually happens to SF's sewage

That's the rate at which water comes into the system, projected out over a whole day. Today's rains changed tripled that amount.

"In the last hour we've seen the flows go all the way up to 165 million gallons per day" according to White.

She says the wastewater treatment system is designed to clean up water filled with sewage before it's returned to the bay. But, old, leaky municipal water mains and the pipes leading from homes allow millions of gallons of rainwater to mix in.

"We want to keep wastewater in the wastewater system and the separate system in the East Bay for the stormwater," she says.

Too much stormwater infiltration could create overflows and spew untreated sewer water into the bay.

RELATED: Crews in Oakland work overtime to keep sewage treatment plant from overflowing

Although the system can handle up to half a million gallons per day in an emergency, system operators start to worry when flows top 170 million gallons. By 1 p.m. this afternoon, they reached 200-million gallons.

That forced East Bay MUD to open it's Pt. Isabel facility in Richmond to divert and store some of that excess water until things calm down.