Consultants Recommend Pilot Sewer Infiltration Program

The engineering consultant hired to analyze Whitefish Bay's sewers is recommending the village adopt a pilot project to eliminate clear water in the sanitary sewer system, which contributes to basement backups.

Steve Sticklen, of Donohue and Associates, recommended at Monday night's board meeting that the village implement a pilot private property inflow and infiltration program in the southeast corner of the village, an area of the village that he said poses less variables because it is at a higher elevation.

Sticklen said a pilot program would demonstrate the effectiveness of a PPII program, which could require homeowners to disconnect their foundation drain and/or repair or replace their lateral.

“The evidence overwhelmingly indicates private property is producing the majority of inflow and infiltration,” Sticklen said. “The idea of a pilot program is to clearly demonstrate that.”

Village Engineer Dan Naze said 25 percent of the sanitary sewers in the village have been upgraded, and about 95 percent of the sewers in the public right-of-way have been monitored with cameras, which suggests much of the clear water is coming from leaky private laterals.

Based on findings from gathering flow data from across the village between May and August, the consultant showed the areas that have more clear water in the sanitary sewer in the north and in the southwest area of the village. Some areas in the southwest area of the village have very little clear water entering the sanitary sewer system, though. Sticklen said the majority of the clear water is coming from private property.

As part of the consultants’ report finalized in December, Sticklen said they believe about 75 percent or 80 percent homes have gravity foundation drains, while the other 15 percent of homes may have downspouts contributing to infiltration by being tied into their service lateral, which is illegal.

Naze said downspouts have been inspected during the time of a home sale since about 2004 or 2005. Out of 220 homes served by an eight-inch sanitary sewer, Naze said it only takes 10 to 12 homes with illegal connections to overwhelm that sewer.

Trustee Kevin Buckley asked whether the village should launch a program to inspect illegally connected downspouts to fix the infiltration problem.

"We are missing an opportunity, I think, to do something that is not massively capital-intensive, that with some labor and some enforcement and paperwork, we could remove some gallons. That's the object of the game," he said. "If we're not going to do any big construction projects this year, let's focus on some of the stuff they've talked about."

The flow monitoring conducted last summer showed Whitefish Bay’s rainfall is relatively higher than other communities when analyzed by gallons per acre per day, but is closer to the middle of the pack when analyzed per capita. The amount of rain received in the village during that period of time was moderate, with the largest amount calculated being 3.6 inches in a day.

Because of infrastructure improvements made in recent years, Naze said the village is now able to handle 3.6 inches, whereas some of the storms that caused basement backups in 2008 were of lesser magnitude.