The plan included major pumping stations at Deptford (1864) and at Crossness (1865) on the Erith marshes, both on the south side of the Thames, and at Abbey Mills (in the River Lea valley, 1868) and on the Chelsea Embankment (close to Grosvenor Bridge; 1875), north of the river. The outflows were diverted downstream where they were collected in two large sewage outfall systems on the north and south sides of the Thames called the Northern and Southern Outfall sewers. The sewage from the Northern Outfall sewer and that from the Southern Outfall were originally collected in balancing tanks in Beckton and Crossness, respectively, before being dumped, untreated, into the Thames at high tide.