What We Propose Instead

What follows is a sequense of essays outining how we feel Promontory Point should be restored and maintained in the future, for both aesthetic and sound engineering reasons.

Balancing Planning Goals: The Case for Limestone Revetments

Good planning begins with goals, objectives and priorities. Three objectives are relevant in planning the revetments at the Point: (1) the integrity and continuity of the historical landscape design and its aesthetic; (2) recreational use of the park, shore and lake; and (3) protection of Lake Shore Drive. When there is a conflict, compromises should be made to maximize all objectives to the extent possible without significantly compromising any one.

1. Historical Landscape. The historical design of the Point as created by Alfred Caldwell used limestone blocks as the border between shore and lake, based on natural history and ecological fitness. Underlying this design is the fact that the entire surface rock formation of the Chicago region is fossil-laden limestone. The Park District recognized this recently when it restored the Council Circles from concrete to Caldwell's original limestone design. Caldwell's vision is precisely what gives Promontory Point its uniqueness, and it must be maintained.

2. Recreational functions and access of users. Most recreational sites have certain unique functions. These should not be compromised if they are to be optimally used. One of the Point's unique recreational functions, which emerged near the beginning of its construction, is its easy access for deep-water swimming. In addition, its steps provide places for congregating, strolling, and sunbathing by individuals and social groups along and among the limestone steps.
When access by wheelchairs, rollerblades, and bikes is being considered, care should be taken to adequately separate these functions so as not to compromise traditional uses and create the potential for accidents and conflict between pedestrian users and various forms of vehicular movement. Good recreational planning requires a degree of separation of conflicting functions. Needed wheelchair access should be balanced in the plan so as not to compromise or conflict with traditional uses and historical design features unique to Promontory Point.

3. Shoreline Protection. The Chicago Park District's mission encompasses the first two objectives cited above (aesthetics and recreation), but its plans for Promontory Point seriously compromise these functions in order to maximize the third goal, protection for Lake Shore Drive. The Park District's plan should optimize the original functions of the Point -- aesthetics and recreation -- by considering reasonable compromises regarding the third. Planning for shoreline protection for a period significantly less than 100 years, and with lower standards than those suggested (which are greater than the highest record storm waves) is reasonable in order to accommodate the two traditional functions. Long term maintenance costs should be figured in cost estimates, and the value of historical continuity, aesthetics, and variety of recreational uses must be given their full weight.

--Fred Blum

Comments from the Indiana Limestone Institute

[We asked the Indiana Limestone Institute of America to review the design teams' response to Community Task Force requests that limestone be considered in the Promontory Point project. Here are portions of his response.]

"From all indications, the failure of the existing shoreline project was traced to the wood cribs and concrete filler material [underneath the stones] (interesting in and of itself, given that the proposal is to replace the existing stone with concrete, after the concrete on the project has failed). This began to happen in the 1950s, according to Appendix A-1, some 20 to 40 years after the project had been in place. The report goes on to say that, while the stones are 'very strong,' the concrete and other binding material between the stones weakens and degrades, leaving holes that eventually undermine the structure. Again, one must wonder why concrete would be specified in a rebuild of the project, when, according to the report, it is one of the materials that failed and caused the problem....

"[T]he statement is made that rebuilding with new stone is not favorable due to the 'low availability and high cost of this type of stone.'... Our quarries have provided this type of stone for shorelines in various parts of the country for many, many years....

"Finally, in reading the various reports, it seems obvious that the concrete people have lobbied long and hard to get their product specified on this project to replace the stone that has been in place for the past 70 to 90 years. The report contends that the concrete proposed for the project will last 'closer to 100 years.' It might be educational for your group to request names and locations of similar projects that are 'closer to 100 years' old and go look at them to see how they've held up, both from the standpoint of durability and aesthetics....

"Indiana Limestone has been in use for over 170 years, since the first quarry opened in Stinesville in 1827. Breakwater applications, such as the Promontory Point project, have long been a staple of our industry. Buildings using the material exist in every type of climate and the industry can boast of many buildings that are 50, 60, 70, and even 100 years old and older.... With a projected 600 to 1000 year supply of our stone, 'the Nation's Building Stone,' remaining, we look forward to a bright future."

Jim Owens
Executive Director
Indiana Limestone Institute of America

Fred Blum
August 28, 2001
Quarry Stone for the Point

The task force has commendably raised most of the important issues about the Park District’s plan for Promontory Point. However, its recommendations for correcting the Park District’s proposal for the revetment should explicitly demand quarry stone rather than concrete. The decision to use quarry stone is very important because virtually all the concerns about lake access, visual beauty, long term shoreline protection, maintenance, and short and long term economy would be maximized and hinges on utilizing existing and additional quarry stone. Since the Park District has not, as yet, contracted for construction, there is time to redesign the shoreline revetment.

With the US Army Corps of Engineers administering the federal funds allocated to the Chicago Park District and the City of Chicago for Promontory Point , the Corps’ usually, when funding its projects, tends to emphasize the use of concrete and steel construction and to justify their allocations by designating such projects for storm and flood control (see US Army Corps of Engineers, Chicago District websites). The Chicago Park District’s support of the Corps’ designation as flood and storm control in order to get funding for the shoreline may be a significant factor in compromising its primary role to support the park and recreational use of the shoreline. However, the Corps usual tendency for its project designs to be under the influence of local concrete and steel contractors has occasionally been contradicted by the studies and information produced by its own capable national research staff . It has taken years for the technical staff to consider other solutions than the construction of levees, dams, and steel and concrete barriers to protect against floods and storms . One of the major influences to modify national and technical research staff findings from the Corps local projects has been that of natural hazards research and its emphasis on human adjustment to natural ecology led by Gilbert White at the University of Chicago’s Geography Department beginning in the early 1960’s.

Thus, by viewing the Corps national websites on revetments, one would discover that the Corps’ own research and information favor forms of quarry stone for its flexibility and durability against waves and storms . Specially prepared concrete is recommended by the Corps for possible use only when stone was unavailable. There is no evidence that specially prepared concrete was used for the northern segments of the lakefront shoreline. While specially prepared concrete deteriorates significantly faster than stone, non- special concrete is the least desirable and significantly increases long term maintenance costs. Furthermore, the research literature points out that solid walls, as currently being constructed and planned, even of a special mix are too inflexible in the face of heavy wave action. Stone blocks with some gaps and unevenness reduces the impact of waves and changing surface currents. According to research literature and the Corps’ studies, rip-rap revetments comprised of varied size stone designed in a slope has the maximum flexibility to reduce the impact of waves because of its shift with the changing dynamics of impact-- the favoring of soft vs. hard revetments. The U. Of Chicago’s Crerar Library is a source of current research and technical literature relating to revetments and shorelines including applied surface hydrology (TC330 to TC550, the Corps manuals on shoreline protection and revetments and technical studies by such foremost authorities as Pilarczyk and Wang are accessible).

Short and long term economies favor recycling existing stone even adding dolomite and limestone blocks which appear to be currently available in nearby quarries. Long term maintenance by the Park District leasing local construction cranes to correct excessively shifted blocks and to periodically replace severely damaged ones would be a less costly solution than major repairs of crumbling concrete.

The Chicago Park District , whose primary function is to enhance recreation should give top priority to the interactive as well as the passive nature of the recreational use of Promontory Point’s shoreline. Its design should incorporate the characteristics of its users. These are experienced swimmers unlike the users of the beach area. Easy access for older as well as younger swimmers along the entire point should be the park planning goal. The existing stone blocks have always provided such easy access , and with some replacement and stabilization should be the basis of the shoreline revetment plan. Excessive construction focused wholly on storm and flood control would pre-empt active recreation as well as the visual aesthetics of the Point.