The Chicago Park District and Westrec Marinas are building a new breakwater at the mouth of the Jackson Park Outer Harbor to combat wave damage and reduce silting of the harbor.
Unlike much of the other work being done along Chicago’s lakefront this winter in response to high lake levels and wave damage, the 204-foot-long and 24-foot-wide breakwater is a new build, not just a repair to an existing structure.
The Park District is paying for the $2.3 million project, which will be completed on May 1, according to agency spokesperson Michele Lemons.
The project, which intentionally shifts navigation pathways and sediment transport dynamics in the mouth and offshore of Jackson Park Harbor, was initiated in response to “conditions that have caused the failure of a floating breakwater in the harbor and exacerbated the deposition of sediment in the harbor in the past,” according to the project permit application.
The permit was submitted in 2019 to the US Army Corps of Engineers (USACE) by the Chicago Park District, Westrec Marinas, the firm that manages Jackson Park Harbor, and AECOM, the project engineer. The USACE approved the permit application for the work in August of 2020.
“Lake currents and waves regularly transport sediment into Jackson Harbor and especially the east portion of the harbor where boat docking takes place,” states the permit application report produced by AECOM. Sedimentation is an issue because it decreases the depth of the harbor, limiting the draft of vessels that can enter. Buildup of sediment has occurred in the past, and has required dredging to clear the harbor.
Although the harbor is “partially protected from large waves originating from the north,” by the 63rd Street Beach south pier, the report notes that waves diffracted into the harbor mouth as they pass by that pier are “significant and have caused the failure of the existing floating breakwater” in the harbor.
In the permit application, the City proposed to “implement harbor mouth improvements on a fast track basis to address the ongoing failure of the existing floating breakwater that has caused a partial harbor closure.”
The project went through the USACE’s Agency Request for Comment (ARC) process that involved notification of relevant local, state, and federal agencies.
During the review process, responses from the US Coast Guard and users of Jackson Park Harbor concerning the width of the navigable channel between the lake and the harbor led to substantial design changes in the project. An early design proposed the construction of two breakwaters at the mouth to the harbor. The current working design involves the construction of a single breakwater that results in a harbor entry channel that is more than half the width of the existing channel.
According to internal communications between the USACE and AECOM obtained by the Herald through a Freedom of Information Act, a particular concern of the project’s engineers was its impact on the extant promenade wall along Promontory Drive that was constructed in 1893 as part of the Columbian Exposition. The communications reveal that the historic promenade wall will be maintained in its current state and be separated from the new breakwater by the promenade itself (which is about nine feet wide) and a one-foot gap between the outer edge of the promenade and the new breakwater.
Jackson Park Harbor sits within the area covered by the South Lakefront Framework Plan, a working “vision” for Jackson and South Shore Cultural Center Parks that was updated and presented to the Chicago Park District Board of Commissioners in April of 2018. The Framework Plan is not prescriptive, but it is the document that the Park District uses as a guide as it plans and executes projects.
The framework plan includes the combining of the South Shore and Jackson Park Golf Courses into a single golf course; the construction of the Obama Presidential Center; the enhancement of water interconnectivity within the lagoons of Jackson Park; Jackson Park Harbor improvements; and, significantly, shoreline enhancements along the La Rabida Children’s Hospital and South Shore Golf Course lakefronts including construction of beaches and breakwaters.
In response to questions from the Herald, Heather Gleason, Director of Planning and Development at the Chicago Park District, wrote, “The work going on at Outer Harbor adheres to the principles laid out in the South Lakefront Framework Plan, which include leveraging infrastructure improvements and catalytic projects to springboard the parks to ‘another century of greatness.’”
“The South Lakefront Framework Plan called for a habitat beach and stone breakwater for the La Rabida edge and still remains the long-term plan for that portion of shoreline. Among many other water-based recommendations in the plan, it also called for an increase in harbor slips and docks in Outer Harbor.
“The groin project and seawall repairs in Outer Harbor are in direct response to historic storm damage and wave action. The erosion experienced on the south edge of Outer Harbor threatened to undermine the Lakefront Trail—a major investment and community amenity. Significant wave action also caused damage to harbor docks and erosion to the Coast Guard Station,” concluded Gleason.