A simulation of a minor rainstorm found that four times more stormwater would leak into sewer laterals in several neighborhoods in the City of Wauwatosa than into the city sewers under the streets, according to an engineering consultant’s report described in The Milwaukee Journal Sentinel.

The report found that a total of 380 gpm of infiltration would come from a group of homes along one street, and city engineer Bill Wehrley said that showed a need for all communities in the area to identify and help fix leaky laterals. The report said actual leakage from the laterals would have been much greater during the extremely heavy rains that hit the area in July.

"If 20 percent of our problem is from public sewers and we fix that, then 80 percent of our problem still looms out there," Wehrley told the newspaper.

The paper reported, “After severe flooding and widespread basement backups July 22, the Milwaukee Metropolitan Sewerage District has proposed spending $150 million in the next 10 years to inspect and help repair private laterals in the 28 communities served by the district. Last month, the commission hired a Chicago company [National Power Rodding] to televise up to 6,000 private laterals in the next 12 months within communities that ask for the help.”