MILWAUKEE COUNTY

MMSD plans to dredge contaminated muck before demolishing Estabrook Park dam

Milwaukee Journal Sentinel

A small pocket of contaminated muck in front of this serpentine concrete and stone wall in the Milwaukee River will be dredged next year, as part of the demolition of the Estabrook Park dam. The deteriorated wall and dam will be removed by the Milwaukee Metropolitan Sewerage District.

A preliminary plan for removal of the Estabrook Park dam on the Milwaukee River calls first for dredging a pocket of contaminated muck that has accumulated in front of one section of the structure, Milwaukee Metropolitan Sewerage District officials said Monday.

An estimated 250 cubic yards of sand and muck will be scooped out of the riverbed immediately upstream of a serpentine concrete and stone wall south of an island in the river, MMSD Project Manager Tom Chapman said. A dam with floodgates is north of the island.

The riverbed in front of the dam wall must be drained of water prior to dredging. To do that, contractors will install a temporary dam around the muck to block out the river, Chapman said. He spoke Monday at a meeting of the MMSD commission.

Dredging and dam demolition are scheduled to begin in the spring of 2018, according to Chapman.

About 2,000 cubic yards of concrete and stone debris — at least 200 truckloads — will be removed from the river during demolition, he said.

MMSD will present preliminary plans for the work at a May 31 public meeting to be held at the Holiday Inn-Milwaukee Riverfront, 4700 N. Port Washington Road. The meeting is scheduled from 4 to 7 p.m.

The project includes removal of the deteriorated, 1930s-era dam with floodgates, ice barriers upstream of the dam, and the concrete wall. Cost of the work is estimated at $1.7 million.

In January, the district bought 45.7 acres at Estabrook Park from Milwaukee County for $1 for the purpose of demolishing the dam. Much of the property was returned to the county for park use at the time of the sale.

MMSD held on to a narrow 3.9-acre parcel along the river on the north end of the dam, and the island at midstream, for equipment access during demolition. That parcel will be returned to the county for park use after the work is done.

The district currently is seeking federal and state permits needed to do the work. Final demolition plans will be presented to the public at a meeting in September, according to Chapman. Officials expect to award a demolition contract by the end of this year.

MMSD Executive Director Kevin Shafer said most, if not all, of the estimated $1.7 million cost will be financed with grants. To date, the Fund for Lake Michigan awarded a $250,000 grant to help pay for the project.

Demolishing the dam will save public funds while improving water quality and reducing flood risks to upstream properties in the river's floodplain, according to Shafer. Repairing the dam and its upstream ice barriers, along with providing a fish passage, would have cost the county an estimated $4.1 million.

Dam gates have been open since state inspections in 2008 found numerous safety problems and confirmed the need for extensive repairs. In 2009, the state Department of Natural Resources ordered the county to remove or repair the dam.

The deteriorated, 1930s-era Estabrook Park dam on the Milwaukee River will be demolished in 2018, Milwaukee Metropolitan Sewerage District officials said.

Two years ago, a sand cover was placed over the small pocket of contaminated muck in front of the serpentine dam wall as a barrier to prevent toxic chemicals known as PCBs from being released to the environment, Chapman said.

This deposit was left behind during the federally managed cleanup of PCBs in the river bottom upstream of the dam to Lincoln Park because it contained such a low level of contamination, less than 1 part of chemicals per million of muck. But one sample of the muck contained 1.3 ppm of PCBs so the district chose to remove the deposit and sand cover as part of the demolition project, he said.