Chicago Shoreline Protection Project - Chicago, Illinois

New stepped revetment and waterfront promenade. Source: Chicago Park District/MWH Global

Basic Facts Location: Chicago, Illinois, USA Main points: shoreline protection, revetment design, flood and storm damage reduction, public water access, recreation, construction phasing Size/length of waterfront: 8 miles of Lake Michigan shoreline Year implemented: 5.8 miles constructed, with completion anticipated in 2015 Clients: US Army Corps of Engineers, City of Chicago Department of Environment, Chicago Park District Cost: $354 million Relevant Issues Habitat and Environment: Littoral drift Dune habitat re-creation Migratory bird habitat Tree protection and preservation Public Use: Water access Gathering space Parkland and beaches Bicycle and pedestrian paths Design and Construction: Shoreline stabilization - construction over the existing revetment Phasing to allow concurrent construction contracts Maintaining public access

Original revetment deterioration. Source: Chicago Park District/MWH Global New stepped concrete and sheet pile revetment. Source: Chicago Park District/MWH Global

Overview

Chicago’s turn-of-the-century revetments have been degraded due to storm erosion and natural weathering, which led the City of Chicago Department of Environment and US Army Corps of Engineers to begin replacement of the eight-mile revetment. Stabilization of the shoreline is necessary to protect Lake Shore Drive, a federal highway, and the city’s lakefront park land. The primary means of stabilization is a steel sheet pile-faced, stepped concrete revetment. In select areas, the stepped revetment is interrupted by rubble mound revetment and by beaches. Most of Chicago’s beaches consist of natural, fine-grain sand captured from littoral drift with groins and protected by off-shore breakwaters. The project has also examined the creation of natural sand and gravel beaches with fore-dune, backdune, and wetland habitats that occur naturally in undisturbed shoreline areas.

Habitat and Environment

Chicago’s turn-of-the-century revetments have been degraded due to storm erosion and natural weathering, which led the City of Chicago Department of Environment and US Army Corps of Engineers to begin replacement of the eight-mile revetment. Stabilization of the shoreline is necessary to protect Lake Shore Drive, a federal highway, and the city’s lakefront park land. The primary means of stabilization is a steel sheet pile-faced, stepped concrete revetment. In select areas, the stepped revetment is interrupted by rubble mound revetment and by beaches. Most of Chicago’s beaches consist of natural, fine-grain sand captured from littoral drift with groins and protected by off-shore breakwaters. The project has also examined the creation of natural sand and gravel beaches with fore-dune, backdune, and wetland habitats that occur naturally in undisturbed shoreline areas.

Public Use

Proposed habitat beach. Source: Chicago Park District New 42nd Street recreational beach. Source: Google Earth

Located in the heart of 23 miles of continuous public shoreline, creating an accessible and recreational waterfront was crucial to the project. Planning was coordinated with the master plans for Lincoln, Grant, and Burnham Parks along the waterfront and included a public input process to protect and improve recreational access and use of the waterfront. The stepped revetment structure provides informal seating and a water-edge promenade for strolling, sun bathing, fishing, and gathering at events such as the annual air show, boat regattas, and fireworks displays. Periodic sloped walks between the stepped levels provide accessibility for people with disabilities. Along the promenade, ladders, throw buoys, and seiche cables (a cable one can grab onto in the instance of a large over-topping wave) were included for safety. Inland, an existing bicycle and pedestrian path was widened, enhanced, and rerouted to maintain use throughout construction. Beaches were established in areas with high access and visitor potential.

While the project has been publicly successful, controversy arose over replacing a small segment of original revetment surrounding Promontory Point, a historic park. Debate continues as to whether or not the original revetment contributes to the park’s historic significance; to date, this revetment has not been replaced.

Design and Construction

Construction is divided into multiple reaches and phased in order to address areas of highest need, coordinate with adjacent projects, maintain public access (especially during summer months), and allow multiple construction contracts. Because of the project’s size, multiple contracts allow several contractors to work on the shoreline in different areas. The new stepped revetment is constructed by driving steel sheet piles on the water side of the existing revetment, creating a coffer dam where the new stepped concrete revetment can be formed, poured, and finished. In most areas, the existing revetment was left in place as fill, with some intact stone or concrete blocks salvaged for reuse elsewhere. Construction began in 1999 and will be complete in 2015.

Lessons

• Sheet pile and stepped concrete revetment structure employed through most of the eight-mile project, with greater design attention given to beaches and water touch points in high public use areas
• Stepped levels and waterfront promenade in revetment provide for recreation and wave energy deflection
• Sloped walks traversing the stepped revetment levels provide accessibility
• Ladders, throw buoys, and seiche cables included as safety measures
• Aquatic and terrestrial plant, animal, and migratory bird habitat developed
• Revetment constructino provided opportunites for new parkland creation on file areas and improvements to existing parkland and bicycle/pedestrian path
• Construction phased to allow multiple contracts and maintain public shoreline access

Resources

City of Chicago project summary.
"Rehabilitation of the Chicago Shoreline: A Coastal Engineering Perspective."
Michael Krecic, P.E. Taylor Engineering, and Mark Wagstaff P.E. MWH Global.
Great Lakes Urban Habitat Symposium.
Chicago 2009 Morgan Shoal: Planning for a Sustainable Ecosystem & Shoreline Protection for Lake Michigan.
Rejman, Rob. Chicago Park District.