Converting a degraded quarry into a community asset

September 2012 » Features » PROJECT CASE STUDY
Multiple stormwater best management practices and erosion controls improve water quality and reduce flooding.
Ted Gray, P.E., CFM, CPESC
The project area is shown soon after construction. Eroding slopes were converted into a series of eight terraced wetlands (front left foreground). More than 86 acres of restored area has zero discharge of runoff to offsite areas through the 100-year, 24-hour storm recurrence interval. Runoff is filtered through native plantings, retained, stored onsite, and either evapo-transpired or infiltrated in the ground.

The Jelke Creek Bird Sanctuary is a 239-acre area located in the Village of Sleepy Hollow, Kane County, Ill. The site, purchased by Dundee Township in 2000, is bordered by 2,000 feet of Jelke Creek to the west and residential subdivisions in other areas. Jelke Creek contains several desirable fish species as well as a variety of freshwater mussels.

Project
Jelke Reclamation Project, Kane County, Ill.

Participants

Dundee Township, Ill.
Living Waters Consultants Inc.
G.A. Blocker Grading Inc.
Applied Ecological Services

Plan

Create a natural recreation area that enhances the community and improves water quality.

However, the value of Jelke Creek and the newly acquired Bird Sanctuary were compromised by historic aggregate mining activities. Approximately 50 percent of the project site (120 acres) had been disturbed and degraded by quarry activities. Moderately eroding slopes occurred along approximately 4,300 linear feet of the project perimeter. Typical conditions included 2:1 (H:V) or steeper unvegetated areas with heights extending to 20 feet. Sheet, rill, and/or gully erosion was common throughout the area. Soil-stabilizing vegetative cover was lacking because of a lack of organic matrix in the topsoil.

Three degraded onsite ponds contained more than 2,000 linear feet of eroding banks. Despite permeable soils, disturbance and compaction caused silt-laden runoff to discharge through the gated south entrance toward Jelke Creek during flood events. Water quality impacts, including siltation, sedimentation, nutrient enrichment, and habitat degradation, extended downstream to Jelke Creek.

Project goals
Dundee Township's primary goals for the Jelke Reclamation Project included improving water quality and reducing flooding from the degraded site. Project engineers determined this could be accomplished by retaining as much rainwater onsite as practicable through storage, infiltration, and retention. Reducing offsite runoff would reduce the discharge of pollution into Jelke Creek, increase infiltration, and increase groundwater recharge. Groundwater recharge could help protect regional groundwater aquifers as well as stream hydrology and ecology.

Terraced wetlands, stabilized with erosion blanket after construction, were constructed along previously eroding slopes exceeding 20 feet in height. The eight terraced wetlands have a combined flow path of 4,000 linear feet and filter, detain, and infiltrate runoff.

Converting the eroding site into stabilized areas with deep-rooted native vegetation was considered essential to accomplish these goals. In addition, Dundee Township sought to improve recreational opportunities for the community.

Natural log toe structures were used to stabilize deeper shoreline areas subject to wave erosion. Erosion blanket was installed in shoreline areas adjacent to the natural log toe. In most cases, wetland plantings have become established between the logs and the shoreline areas.

In 2007, Dundee Township prepared the Jelke Reclamation Project Concept Plan with engineering assistance from Living Waters Consultants Inc. The Concept Plan process began by first evaluating site resources rather than focusing on existing problems. The goal was to take advantage of the site's permeable soils, aggregate stockpiles, limited topsoil stockpiles, ponded areas, as well as proposed wetlands to achieve project goals.

Before reclamation, pond shoreline areas were disturbed by quarrying impacts and bank-stabilizing native vegetation was lacking.

Final engineering included the application of environmentally sound restoration engineering techniques within the context of the comprehensive site evaluation. Living Waters Consultants was hired to provide stormwater design, final engineering plans, ecological design, permitting, bidding assistance, construction observation, grant acquisition assistance, and ongoing maintenance and monitoring inspections. The lowest qualified bidding contractor, G.A. Blocker Inc., was well-suited to large-scale, earth-moving projects.

Project summary
Stormwater best management practices (BMPs) included minimization of impervious areas, minimization of storm piping or curbed drainage, installation of bioswales, filter strips, native vegetation, infiltration areas, rock checks, wetland detention, sediment forebays, pond shoreline re-grading for naturalized appearance, and other measures.

BMPs installed over 120 acres of degraded project area included the following:

  • conversion of 40 acres of eroding berms and stockpiles into stable slopes supporting native plantings;
  • seven wetland filtration basins totaling 18.2 acres in area;
  • conversion of one existing pond into a naturalized detention basin 0.5 acre in area;
  • eight biofiltration swales totaling 3,670 linear feet;
  • eight terraced swales more than 4,000 linear feet in combined flow path length;
  • 49 rock checks;
  • five sediment forebays;
  • more than 875 linear feet of natural log toe and/or log habitat structures;
  • 111 acres of native plant seeding; and
  • 3.6 miles of walking trails.

Approximately 260,000 cubic yards of earthwork was applied over approximately 84 acres of area. Exposed and eroded substrate soils were re-graded to stable slopes, recreational areas, or converted into BMPs. Topsoil stockpiles around the perimeter were re-spread over graded areas.

Five sediment forebays were installed at various major inlet areas. Sediment forebays detain and store inflowing suspended solids and allow for periodic cleanout of the solids. Shoreline areas were stabilized with North American Green S150 BN or S75 BN biodegradable erosion control blanket, depending on site slopes. Native plant seed and native plant plugs were installed at each wetland and erosion control blanket was installed along shoreline areas. In areas that did not receive erosion blanket, straw mulch was hydroseeded to provide temporary stabilization. In areas where concentrated flow could occur, rock checks were installed. Previously unvegetated berms, stockpile areas, and spoil piles were converted into stable slopes vegetated with deep-rooted native plantings.

A restored wetland filtration basin is depicted with two rock checks in the foreground. The site provides a regional amenity for flood control, hiking, fishing, aquatic habitat, species diversity, and other benefits.

Seven wetland filtration basins were constructed with a total area of 18.2 acres. The wetland filtration basins ranged from 0.5 acre to 6.9 acres in area. Four wetland filtration basins are equipped with Agri-Drain type inline water level control structures to regulate water levels. The adjustable water level control structures allow for periodic water level drawdowns, if necessary, to provide wetland maintenance. The seven wetland filtration basins will improve water quality through filtering suspended and soluble nonpoint source pollutants, increasing retention and infiltration of runoff, recharging groundwater, and reducing offsite polluted runoff.

Eight biofiltration swales totaling 3,670 linear feet were constructed along impervious surfaces such as the 30-stall parking lot or the entrance road, or along adjacent hillslope areas. The biofiltration swales were composed of modest depressions lined with topsoil amended with sand to increase permeability. The topsoil typically was underlain with 2 feet of course aggregate (from onsite sources) to enhance infiltration and provide subsurface runoff storage. Biofiltration swales were stabilized with erosion control blanket. Native plant seed and plugs also were installed.

More than 111.4 acres of native plant seeding was installed. Native plant seed mixes included shoreline, mesic prairie, dry prairie, emergent wetland, biofiltration swale, and mowed trail lists. More than 54,000 native plant plugs or tubers were installed in 2010.

More than 86 acres of the project site now retain and infiltrate runoff from the sub-watershed through the 100-year, 24-hour rainfall recurrence interval. Flood control, water quality, and ecological benefits include retention and filtration of runoff by wetlands, native plants, bioswales, and onsite aggregate soils; long-term site stabilization; habitat diversity; species recovery; improved site aesthetics; and protection of downstream Jelke Creek and the Fox River basin. Native habitats range from deep emergent wetland to emergent areas, mesic shorelines, hillside seeps, upland dry prairie habitat, and woodland areas.

Project implementation demonstrated environmentally sound stormwater management, conversion of a degraded facility into a restored area suitable for community recreation, enhanced ecological diversity, improved water quality, community education, and improved property values. Construction costs were approximately $1.76 million.

Dundee Township acquired $897,735 in grant funding from the Illinois Environmental Protection Agency (Section 319 Grant Program). In addition, more than $400,000 in grant funding was received through the Illinois Department of Natural Resources Open Space Land Acquisition Fund. The Chicago Metropolitan Agency for Planning provided grant administration.

Living Waters Consultants provided engineering services, G.A. Blocker Grading Inc. provided construction, and Applied Ecological Services provided native plant installation and maintenance. Project owner Dundee Township continues to manage and maintain the project site. The Jelke Creek Restoration Project recently was awarded the Stormwater Project of the Year by the Illinois Association for Floodplain and Stormwater Management.

Ted Gray, P.E., CFM, CPESC, is an engineer/fluvial geomorphologist with Living Waters Consultants Inc. (www.livingwatersconsultants.com). He can be contacted at 630-321-1133 or tgray@livingwatersconsultants.com.

Read more about the Jelke Reclamation Project and view additional photos online at http://tinyurl.com/JelkeReclaim.


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