HeatherRidge Report

What You Can Do

REDUCING RUNOFF AND ADDING BIODIVERSITY
at the HeatherRidge Community of Gurnee, Illinois

EXECUTIVE SUMMARY

The members of the HeatherRidge Conservation Club had become concerned about erosion and water quality problems at the ponds in their community. They wished to solve local drainage problems in ways that improve the health of the entire watershed. Beginning in 1998 and assisted by a consulting team funded by the Conservation 2000 Program of the Illinois Department of Natural Resources, they developed a plan that they will begin implementing during 1999. The plan encourages runoff reduction, which is accomplished by establishing deep-rooted native vegetation where it can intercept significant quantities of stormwater and soak it into the ground before the water reaches a pond or stream.

Public agencies often spend decades seeking sites to store water in sufficient quantities to reduce flooding downstream in a watershed. Sites for these structures can rarely be found and developed fast enough to make up for the additional runoff from impervious surfaces of residential, retail and industrial areas. In order to avoid increased damages from flooding in rapidly developing areas, and to mitigate related problems of streambank erosion caused by flow instability, an aggressive effort should be made to provide land for infiltration as development occurs. This could offset the effects of increased runoff from land made impervious. Runoff reduction, fortunately, can be accommodated on both new and existing development sites. Runoff reduction has the additional benefits of reducing the load of pollutants from urban areas, a major cause of the deterioration of urban streams, and recharging local groundwater aquifers and supplementing stream baseflows. And the establishment of native plants increases the biodiversity of the landscape and reduces long-term maintenance needs. The lessons learned at HeatherRidge could be important throughout the Des Plaines Watershed, where flood damages average over $21 million per year. If runoff reduction can become widespread in the Des Plaines watershed, there is hope that flood damages can stop inevitably growing as new development continues.

HeatherRidge, a community of 900 residences on 300 acres, is an attractive location to demonstrate the potential for reducing runoff, and to demonstrate the acceptability of modified landscapes to local residents. Developed in the late 1970s, HeatherRidge won awards for its innovative landscape design. The community still takes great pride in the beauty and intricacy of its neighborhoods. A nine-hole golf course parallels Spinney Run, a tributary of the Des Plaines River, as it flows through HeatherRidge. The most striking features of the site are 29 ponds, ranging from 0.05 acres to 2 acres in surface area. Four of the ponds are behind dams in Spinney Run.

Even though HeatherRidge was designed more than 20 years ago, there are numerous examples of attractive features that subtly move stormwater from roofs, parking areas and lawns to ponds and drain pipes. But, as with parts of all large systems, problems have developed with some of the HeatherRidge ponds. Erosion of grassed areas and pond banks occurs, and pond water quality and habitats could use improvement. It is suggested here that parts of the stormwater management system be improved by replacing some of the turf grass with native vegetation. The changes will enhance the filtering of water, and will increase the infiltration of water into the ground. Infiltration will have local benefits by reducing the "bounce," or frequent rise and fall of the water level that causes erosion of pond banks. Infiltration will also have regional benefits by reducing the flow of stormwater during flood periods from HeatherRidge to the Des Plaines River.

The potential benefits to be gained from installation of native vegetation in parts of the HeatherRidge landscape were estimated using computer modeling. Although measurements of infiltration rates for native vegetation are still being made, and are not yet available, conservative assumptions were used to prepare graphs that can be used for design of these and other projects.

Four projects are recommended. Each of them consists of several tasks that can be accomplished within a year of two with modest budgets. The locations of the projects are shown in Figure 1.

Project I - Ponds 1 and 2 and the Golf Course Swale

This area contains the two ponds that are most visible to the average resident or visitor to HeatherRidge. The first task, which can be implemented starting this Spring, is to improve the erosion resistance of the swale bordering the first fairway of the golf course by incorporating native vegetation at key locations. Another task would improve Pond 1 with shoreline and emergent pond vegetation that will provide additional habitat, reduce erosion, and make the pond more interesting and attractive. Whenever it is practical, another task could incorporate native vegetation into the steep slope north of Pond 2 to reduce runoff of lawn chemicals and grass clippings to the pond. And a fourth task could include construction of a small wetland or stilling basin in Pond 2 to capture sediment from the street and parking areas.

Project II - Ponds 5 and 6

These two ponds are contained in a large, attractive glade set among about 40 residences.

A modest effort could incorporate native vegetation into shorelines and swales that transmit water to the ponds, starting with those that are eroding. Emergent and floating- leaved vegetation could be added to the ponds. And Pond 6 could be deepened in the future by moving sediment to the south end where wetland vegetation can be attractively placed.

Project III - Pond 3

This pond has been a problem for years, and is a priority because of the fervor of its neighbors. The pond is very small and hidden from the streets, so that only 20 residences are affected by it. But the pond dries up most summers, which greatly disturbs the neighbors. The old liner and riprap could be removed and replaced with natural shoreline. Sediment could be moved within the pond to deepen the north end and reduce the depth at the south end so that emergent vegetation can be added at the pond outlet. An additional option would be the inclusion of a recirculating pump and filter so that water could flow continuously through the wetland into the pond.

Project IV - The Golf Course

The manager of the golf course, golfers and members of the Umbrella Board are discussing overdue improvements to the course. Some of these have to do with safety, since there are places in the course where golfers are tempted to cut close to residences with their shots. Other improvements would improve the playability of the course for the average golfer by reducing the difficulty of shots over ponds and along streams. An effort should be made as construction is planned to identify areas on and adjacent to the golf course where attractive, low maintenance native plant materials can be used to reduce erosion and runoff. Two areas that have already been identified are near the 5th and 7th greens. Restoration of eroded banks is recommended on the west branch of Spinney Run along the 3rd and 4th fairways and at the confluence of the north and west branches. The golf course managers should investigate and seek Audubon certification for habitat enhancement. Many local clubs have done this.