Sewage backed up into a Prince George's County condo building, causing the evacuation of four units after midnight on Sunday.
A malfunction at the Greenbriar Wastewater Pumping Station in Greenbelt led to the overflow. In addition to fouling the condominium units, some sewer water spilled out near the plant, at 8021 Mandan Road in Greenbelt.
Washington Suburban Sanitary Commission said 46,000 gallons of wastewater ran out onto the ground there. The commission said the spilled sewage did not reach any waterways.
The problem originated with a mechanical failure in the pumping system, WSSC said. The Maryland Department of Environment has been notified.
