By Brent Killackey
Journal Times | Posted: Monday, August 20, 2007 12:00 am
RACINE - The weekend's record heavy rains overwhelmed the Racine's Water and Wastewater Utility, prompting the discharge of 3.78 million gallons of untreated wastewater into the Root River and Lake Michigan.
That quantity is the equivalent of filling a football field-sized space with 30 feet of water, according to Keith Haas, general manager of the utility.
The wastewater was deliberately dumped to prevent sewage backups into basements, Haas said. Despite the utility's efforts, sewage entered a few dozen homes.
The wastewater treatment plant reached a new peak flow of 231 million gallons per day during the weekend, he said. That is still well below the 308 million gallons per day capacity. However, the wastewater sewers could not handle the heavy volumes, which prompted the discharges.
Racine's utility has separate storm water and wastewater sewer systems. But water still enters Racine's wastewater system through foundation drains in homes built before regulations changed in 1960, Haas said. The water percolates through the ground - a phenomenon dubbed "clear water infiltration" - into the wastewater sewers; it is cleaner than storm water, he said.
Because of this weekend's high volume of clear water infiltration, the sewage discharged into the Root River and Lake Michigan was "very dilute," Haas said.
The 24 hours from 8 a.m. Saturday morning to 8 a.m. Sunday set a record with 4.1 inches of rain, beating the record of 4 inches set on Sept. 11, 1933, Haas said.
During a 48-hour period this weekend, 6.25 inches of rain fell on Racine; normal rainfall for the entire month of August is 4.08 inches, he said.
Racine's last major discharge of wastewater occurred in April 1999, when 7.5 million gallons of wastewater were dumped into the lake, Haas said.
The Milwaukee Metropolitan Sewerage District began discharging combined storm water and untreated wastewater into Lake Michigan at 5:13 a.m. Monday. Information on the volume of the MMSD discharge wasn't expected for several days.
After heavy rains in April, MMSD dumped nearly 400 million gallons of a combination of storm water and untreated wastewater into the lake.