MMSD to remove toxic PCBs
Chemicals cling to north side pipe
The Milwaukee Metropolitan Sewerage District plans to hire an engineering consultant this month to recommend how to remove a few hundred cubic yards of thick and oily, toxic sediment in a major regional sewer on the north side of Milwaukee.
The sediment is contaminated with heavy amounts of chemicals known as PCBs, so a contractor cannot simply wash the gooey mess down the pipe to a wastewater treatment plant.
It looks like molasses mixed with dirt. Paper and plastic trash has stuck to it over the years.
The sticky sediment clings to the bottom of 8,000 feet of this pipe, known as a metropol considered itan interceptor sewer, that runs underground along the west bank of the Milwaukee River from Lincoln Park south to Auer Ave., said Mike Mar-tin MMSD technical services director. Cost of removal is estimated at $3.8 million.
Concentrations of PCBs above 50 parts per million are a hazardous waste. Levels in the sediment range from less than 100 ppm in most locations to a high of 1,660 ppm, according to Martin.
Use of PCBs, or polychlorinated biphenyls, was banned in 1979 after studies linked exposure to the chemicals to immune system damage and cancer.
The primary source of the PCBs in the regional sewer was a former factory, Milwaukee Die Casting Co., 4132 N. Holton St., that used hydraulic fluids containing the chemicals in its die-casting machines.
Fluids leaked from storage tanks and hydraulic lines and accumulated in a city sewer that drains to the regional pipe immediately east of the former factory site north of Capitol Drive at Olive St.
Removal of the sediment will close a costly pollution sto
ry that first gained public attention and notoriety in 2007, a decade after metal casting ended at the plant.
At that time, PCBs were dislodged from the city sewer by an unsuspecting cleaning crew. The toxic load flowed downstream to the regional sewer and on to the Jones Island sewage treatment plant.
Before they were detected in routine tests, the chemicals contaminated tons of Milorganite fertilizer made from sewage sludge removed from the plant, including thousands of pounds that already had been distributed for free for use at Milwaukee County Parks and Milwaukee Public Schools recreational areas. Thirty recreational fields were closed in the summer of 2007 until top
could be scraped off.
Lost sales of Milorganite, disposal of contaminated product and cleanup of the recreation fields cost MMSD nearly $5 million. To prevent another incident of contamination, the fertilizer is tested daily, said Sharon Mertens, MMSD director of water quality protection.
After an investigation, the factory was found to be the primary source of the PCBs, and the district in 2008 ordered the owners, an Ohio couple, to disconnect the plant from the city sewer. In the past, water, sewage and hydraulic fluids collected in pipes beneath the buildings drained to an outdoor sump. The sump drained to the city sewer.
In 2012, the U.S. Environmental Protection Agency determined the closed factory was “an imminent and substantial threat to public health and the environment.”
In 2014, two companies affiliated with past operators
agreed to pay for the EPAmanaged cleanup of the property and removal of buildings at an estimated cost of more than $4 million.
Even though the district started working with the EPA in 2008 on plans for cleaning up the regional sewer, the agency did not approve MMSD’s work plan until December 2015, Martin said.
On Monday, a committee of the MMSD commission will consider the district’s request to pay CDM Smith Inc. of Milwaukee up to $718,766 to provide recommendations on cleanup methods and other engineering services during both remediation of the toxic sediment and subsequent rehabilitation of the regional sewer.
The full commission will act on the contract at its Jan. 23 meeting.
This sewer collects flows from combined sanitary and storm sewers in central Milwaukee and eastern Shoresoil wood.
A cleanup contractor will be hired after CDM completes its recommendations and updates both estimates of the volume of sediment to be removed and cost of the work, Martin said.