MMSD: Estimated combined sewer overflow of over 500 million gallons

MILWAUKEE (WITI) -- The Milwaukee Metropolitan Sewerage District (MMSD) is reporting the following information to the Wisconsin Department of Natural Resources regarding sewer overflows that resulted from heavy rain April 17 and 18, 2013.

Two to three inches of rain fell on most of the MMSD service area, further saturating the ground after heavy rain the previous week.  April 8 through 18, more than five inches of rain soaked the service area, producing more than 35 billion gallons of water (see attached maps).  Every inch of rain on the District equals 7.1 billion gallons of water.

To reduce the risk of basement backups and reserve room in the Deep Tunnel for separate sewer flows, combined sewer overflows were initiated around 4:30 a.m. on April 18 and ended April 19.  The total combined sewer overflow is estimated at 524.9 million gallons.

MMSD took emergency steps to increase treatment capacity and reduce the volume of combined sewer overflows by conducting combined sewage treatment at the Jones Island Water Reclamation Facility starting around 3:00 p.m. on April 17 and ending on April 19.  The treatment procedure is estimated to have reduced combined sewer overflows by 130 million gallons.  Combined sewage treatment involves pumping water directly out of the Deep Tunnel into disinfection chambers at Jones Island.