Kinnickinnic River Environmental Restoration Project

The Kinnickinnic (KK) River discharges into Lake Michigan via the Federal navigation harbor at Milwaukee, Wisconsin. The project area, part of the Milwaukee Estuary Area of Concern (AOC), is an approximately 2000-foot long and 200-foot wide section located between KK Avenue, the downstream limit, and Becher Street, the upstream limit.

Historically, the project area was designed to accommodate navigation with a water depth as deep as 21 feet as recorded between 1915 and 1936. However, due to a decline in commercial navigation traffic, routine dredging stopped for the project area in the early 1940s, but has continued for downstream from KK Avenue by the US Army Corps of Engineers (ACE). At the cease of dredging, sediment has been accumulating in the area and resulted in a very shallow condition. According to a survey conducted in 2002, the water depth in approximately 90% of the area ranges from 0-10 feet. Unfortunately the accumulated sediment is contaminated as a result of evolving urban growth and development and lack of regulations before the mid 1970s. PCBs and PAHs are the primary contaminants of concern.

Efforts have been ongoing through Remedial Action Plan since the 1980s to address the residual contaminated sediment issue and more recently, new navigation needs. Studies conducted between 1980 and 1995 revealed maximum concentrations of 45 parts per million (ppm) and 1,022 ppm for PCBs and PAHs, respectively. A 2002 sediment assessment effort, funded by an USEPA-Great Lakes National Program Office (GLNPO) grant, defined the extent of contamination in the project area. Maximum concentrations of 36 ppm and 244 ppm were detected for PCBs and PAHs, respectively. The results are documented in the sediment assessment report (Altech, 2003). Based on the findings from the assessment, WDNR with the assistance from the USACE completed a pre-engineering design. Eleven project alternatives, including no action and five dredging alternatives combined with two disposal options were evaluated. The details of the evaluation can be found in the Concept Design Documentation Report (USACE and WDNR, 2004). With respect to the project objective to improve the water quality and navigation condition, the restoration alternative has been selected. The alternative calls for dredging up to170,000 cubic yards of contaminated sediments, approximately 90% of PCB mass in the project area, creating an 80-ft navigational channel of 20-24 feet deep with side sloped to 11 feet below the Lake Michigan chart datum (577.5 feet IGLD85) . The dredged sediment is planned to be disposed of on the USACE operated Jones Island CDF.

Over the course of the project a partnership has been established among federal and local government agencies and riparian property owners adjacent to the project area. The WDNR with tremendous support from USEPA-GLNPO, USACE, Port of Milwaukee, Milwaukee Metropolitan Sewerage District, and Kinnickinnic River Business Improvement District is currently working on the final engineering design to further define the restoration specifications. The final engineering design for sediment removal was completed in March 2008. A supplemental design is on-going.