Converting a degraded quarry into a community asset

March 2012 » Web Exclusive » PROJECT CASE STUDY
Multiple stormwater best management practices and erosion controls improve water quality and reduce flooding.
Ted Gray, P.E., CFM, CPESC

The Jelke Creek Bird Sanctuary is a 239-acre area located in the Village of Sleepy Hollow, Kane County, Ill. The site was purchased by Dundee Township in 2000. The Jelke Site contains a large area of open space — a rare resource for northeastern Illinois. The site is bordered by 2,000 feet of Jelke Creek to the west, Boncosky Road to the south, and residential areas to the north and east. Jelke Creek contains fantail darters (E. flabellare), orangethroat darters (E. spectabile), smallmouth bass (M. dolomieu), as well as a variety of freshwater mussels including White Heelsplitters (Laesmigonia complanata). 

However, the value of the site was compromised by due to historic aggregate mining activities. It is estimated that approximately 120 acres or 50 percent of the project site had been disturbed and degraded by quarry activities. Example impacts included approximately 4,300 linear feet of steeply sloped, 20-foot-tall, 2:1 (H:V) or steeper, moderately to severely eroding slopes along the perimeters of the site. Sheet, rill, and/or gully erosion was common throughout the area. Also, soil-stabilizing vegetative cover was lacking due to the lack of organic topsoil covering the site.

Quarrying activities had included topsoil removal, excavation of aggregate resources, and truck hauling. Resulting impacts include unstabilized piles of sand, gravel, and spoil lacking ground-stabilizing vegetation. Moderately eroded slopes ranged up to 20 feet in height. Stormwater runoff from the site contributed to pollution impacts at downstream Jelke Creek.

Three onsite ponds were disturbed at least in part by quarrying activities. The degraded ponds contained more than 2,000 linear feet of eroding banks. In some cases, unconsolidated quarry spoil materials were deposited within or adjacent to the ponds. Shoreline erosion was aggravated by wave action and a lack of ground-stabilizing vegetation. 

Before construction, ponds were degraded by quarrying impacts. Bank-stabilizing native vegetation was lacking.

During flood events, silt-laden runoff had discharged through the gated south entrance toward Jelke Creek. Water quality impacts included siltation, sedimentation, nutrient enrichment, and habitat degradation. Together, these impacts extended downstream to water quality impacts on nearby Jelke Creek, as well as the downstream Fox River. 

Flood impacts included discharge of silt-laden runoff through the south entrance onto adjacent private lands. Ultimately, the polluted runoff would discharge into nearby Jelke Creek.

Project goals
One of the primary Jelke Reclamation Project goals of Dundee Township was to improve water quality and to reduce 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. One of the goals was to strive to achieve zero discharge to offsite areas during major rain events. It was thought that this could be provided from restored portions of the site. Reducing offsite runoff would reduce associated flooding of polluted runoff into Jelke Creek. Augmenting infiltration of runoff at the project site could also increase the percent of groundwater recharge flowing into Jelke Creek.

Groundwater recharge is important to stream hydrology and ecology because it can help augment low-flow conditions, protecting aquatic and riparian habitat. Converting the eroding site conditions into stabilized areas was considered essential to accomplish project goals. Establishing deep-rooted native vegetation was an important part of project success. In addition, Dundee Township sought to improve recreational opportunities for the community. Wetland areas would be restored, diverse habitat would be provided, wildlife species diversity would increase, and expansive hiking trails and fishing areas would be offered. A small entrance road, parking lot, and picnic pavilion would be the finishing touch.

Concept plan
In 2007, Dundee Township prepared the Jelke Reclamation Project Concept Plan with engineering assistance from Living Waters Consultants Inc. “Preparing a Concept Plan was an important first step to get grant funding and to build public support,” according to Sue Harney, Dundee Township supervisor. 

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. 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 regrading for naturalized appearance, and/or other measures. Methods to install these BMPs included respreading topsoil stockpiles to renovate soil quality, re-establishing native vegetation, site grading to construct additional wetland habitat, stabilizing steeply sloped areas, reusing aggregate materials to reduce flood impacts and increase infiltration, installing walking trails, and providing extensive recreational opportunities. 

Grant funding
Based on the Concept Plan, Dundee Township applied for and received two major grant awards for the project. The Illinois Environmental Protection Agency through the Section 319 Grant Program awarded $897,735 to implement the project.  More than $400,000 was received through the Open Space Land Acquisition Fund (OSLAD). The township would not have been able to do this project without grant money from EPA’s Section 319 program and Illinois’ OSLAD program. 

Final engineering and construction
Final engineering was provided by applying environmentally sound restoration engineering techniques within the context of a comprehensive site evaluation. Living Waters Consultants was hired to provide comprehensive services including stormwater final engineering plans, ecological design, stormwater modeling, permitting, bidding assistance, construction observation, grant acquisition assistance, as well as ongoing maintenance and monitoring inspections. 

Photo shows the project area soon after construction (facing south). Eroding slopes were converted into a series of eight terraced wetlands (front left foreground). More than 84 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 evapotranspired or infiltrated in the ground.

In hindsight, a humorous but fitting site condition was encountered the day of the pre-bid meeting. Due to flooding, meeting attendees had to drive through a two-foot-deep flooded entrance area just to access and view the site. Certainly this helped the bidders prepare for what they could expect. Bidders were warned to bring off-road vehicles to the pre-bid meeting. The lowest qualified bidder selected was a contractor well suited to large-scale, earth-moving projects, G.A. Blocker, Inc. The contractor prepared an efficient and effective plan of action to implement the project. The engineer was hired to provide construction observation for the owner. G. A. Blocker was also willing to adapt the plans to site conditions based on subsoils encountered, and other factors. 

Construction activities included moving dirt from the south to construct wetland filtration basins. Fill was placed in the north to construct terraced wetlands. Road graders, dozers, watering trucks, and other equipment were utilized. Aggregate materials encountered were stockpiled (right foreground of photo).

Even though soil borings were obtained, excavation was necessary to reveal, the diversity of subterranean conditions. Subsoil conditions ranged from coarse aggregate remnants to unconsolidated, non-cohesive spoil piles, to some areas with tight clay deposits. Multi-ton chunks of concrete were occasionally unearthed, presumably used for past quarry operations. More than 50 boulders were recovered and utilized for the restoration project. Boulders were used for benches, parking lot bumpers, aquatic habitat, or other uses. 

With approximately 260,000 cubic yards of earthwork over approximately 84 acres, previously unvegetated berms, stockpile areas, and spoil piles were converted into stable slopes vegetated with deep-rooted native plantings. Exposed and eroded substrate soils were regraded to stable conditions for slopes, basins, or BMPs. Topsoil stockpiles around the perimeter were respread over graded areas. Respreading “A horizon” topsoil over the project site was critical to facilitate the growth of ground-stabilizing native plant materials.

However, due to years of neglect and past erosion, topsoil quality was at best marginal. The average topsoil respread depth was at most approximately six inches. For instance, poor soil conditions made trenching of erosion blanket around proposed basin shoreline areas difficult. Due to the site’s permeable soils and thin topsoil layer, areas only 2 feet above saturated soils could become quite droughty. In general, soil conditions caused some concern over the length of time it would take to establish temporary vegetative cover crop and native plant materials.

After completion of earthwork, exposed soils were stabilized with native plant seeding. Native plant species were selected which are relatively tolerant of site conditions such as coarse aggregate subgrade soils. Plant species tolerant of “dry prairie” conditions were selected and installed in many areas above the water table. Erosion blanket was installed around proposed basin shoreline areas, and straw mulch was hydroseeded in sloped areas to provide temporary site stabilization. In some areas where concentrated flow could occur, rock checks were installed.

After construction, wetland filtration basins responded with extensive growth of native plant species. However, control of invasive cattails was also essential to allow native plantings to become established.

Despite the challenges, through regrading of slopes and stabilization of stockpiles, berms, and spoil piles, more than 84 acres of the project site now retain and infiltrate runoff from the sub-watershed through the 100-year, 24-hour rainfall recurrence interval. Retention of runoff occurs through absorption by native plants, infiltration within extensive onsite coarse aggregate soils, establishment of deep-rooted native plants, enhancement of existing ponds and wetlands to provide pollutant filtration and increased infiltration, and construction of new basins and wetlands to maximize runoff retention. 

Native habitats at the project site include deep emergent wetland, emergent areas, mesic shorelines, hillside seeps, upland dry prairie habitat, and woodland areas. A restored wetland filtration basin is depicted. Two rock checks are evident in the foreground. Rock checks were installed to prevent gully formation from upgradient slopes. The site provides a regional amenity for flood control, hiking, fishing, aquatic habitat, species diversity, and other benefits.

Terraced wetlands
Eroding 15- to 20-foot-tall slopes were converted into terraced wetlands. The eight terraced wetlands were built across a 25-foot grade differential, from upstream to downstream. The outer edge of each terraced wetland was bermed to retain runoff. A rock overflow spillway conveyed runoff from upstream to the next lowest terraced wetland. The combined flow path through all terraced wetlands is more than 4,000 linear feet. The wetlands filter, detain, and/or infiltrate runoff from upgradient areas. Downgradient of the terraced wetlands, runoff is discharged into a sequence of four wetland filtration basins (see below). Fill used to construct the northerly terraced wetlands was generated from the excavation of central and southerly wetland filtration basins and biofiltration swales. During most rainfall events, runoff is either retained, absorbed by native plantings, or infiltrated into soils. 

Terraced wetlands, soon after construction, are stabilized with erosion blanket. These wetlands were constructed along previously eroding slide slopes taller than 20 feet tall. Terraced wetlands filter, detain, or infiltrate runoff in sequence along an extensive flow path.

The terraced wetlands function differently based on location, elevation, subsoils, and other characteristics. In most areas, terraced wetlands provide emergent wetland habitat. In some areas, deep emergent habitat or open water habitat occurs. In one area, infiltration has eliminated standing water, but saturated soils remain likely due to subsurface flow from upgradient areas. From a wildlife and aquatic habitat perspective, the various types of terraced wetlands provide a range of habitat diversity. In all cases, terraced wetlands improve water quality. 

Temporary cover crop and native plant coverage was established early along terraced wetlands. A rock overflow spillway serves to release excess runoff from upgradient to downgradient terraced wetlands. A walking trail (foreground) provides access to many of the restored areas at the project site.

Wetland filtration basins
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. Each wetland filtration basin was stabilized through regrading shoreline slopes. In many areas, shoreline grades in these basins were graded to 10:1 or 20:1 (H:V) or flatter. Variable grades along wetland basin shoreline areas were constructed, including installations of islands, deep potholes, or containment berms to provide a variety of elevations over which to establish diverse native vegetation.

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. Erosion control blanket was installed along shoreline areas. In areas that did not receive erosion blanket, straw mulch was hydroseeded to provide temporary stabilization.

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. 

Diverse water depths were provided to facilitate establishing various native plant species. Recreational opportunities are enhanced with walking trails, fishing piers, and wildlife viewing. Dundee Township provided more than 3.6 miles of walking trails.

Biofiltration swales
Eight biofiltration swales totaling 3,670 linear feet were constructed. Biofiltration swales treat and infiltrate runoff from impervious surfaces such as the 30-stall parking lot, entrance road, or adjacent hillslope areas. The biofiltration swales will help to remove suspended sediment, heavy metals, oil and grease, nutrients, and other suspended and soluble nonpoint source pollutants. 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 were also installed. 

Biofiltration swales along the entrance road filter, detain, and infiltrate runoff from impervious surfaces. Onsite gravel and sand aggregate materials were used to provide subgrade materials. In some cases, rock checks were installed. Rock checks were keyed into subgrade aggregate materials to enhance infiltration of runoff.

Rock checks
Rock checks were particularly important to stabilize areas prone to form gullies. Rock checks prevented downcutting at gully areas and reduced runoff velocities. Rock materials utilized ranged from 2-inch cobble to 9-inch or larger rock materials. Since onsite aggregate materials were typically 2 inches or smaller, in some cases, larger rock materials needed to be imported to stabilize steeply slopes areas. Native plant seed was installed along rock checks.

Rock checks were graded into vegetated swales along steeply sloped constructed trail areas to reduce gully formation from tall adjacent slopes.

Natural log toe
Several dozen felled trees were reused as natural log toe structures to provide natural shoreline stabilization. In most cases, the trees were obtained during the removal of invasive trees from topsoil stockpile areas. Selected logs were installed along shoreline areas parallel to the shoreline to maximize the length of shoreline protection. Cut logs with minimum 10-inch diameter and 20-foot length were used for natural log toe structures. Logs were secured to the subgrade using wood stakes fastened with rope. The natural log toe was installed to protect shoreline soils from erosive wave action. They also promote wetland formation. Shoreline areas were also stabilized with erosion control blanket, native plant seed, and native plant plugs. 

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.

Log habitat structures
Log habitat structures were also obtained during the removal of invasive trees from topsoil stockpile areas. The habitat structures were typically offshore within wetland filtration basins. The structures not only dissipate wave action in the wetland filtration basins but also provide aquatic habitat diversity. Wetlands adjacent to log habitat structures were seeded with native plant seed and native plant plugs. 

Native plant seed, plugs, shrubs, and trees
Selection and installation of native plant seed, plugs, shrubs, and trees was important for project success. More than 111.4 acres of native plant seeding has occurred throughout the project site. 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. Native plant plug mixes included shoreline, mesic prairie, dry prairie, and aquatic tuber lists.

Establishment of native plant materials will increase long-term stabilization, pollutant filtration, nutrient reduction, habitat diversity, and site aesthetic values. Native plants have the capability to develop deep and dense root zones to enhance stabilization, filter polluted runoff, and improve species biodiversity. This is critical considering the fragile nature of the site’s mineral soils.   

Recreation
A self-guided environmental education trail was provided to enhance public education and outreach. More than 3.6 miles of walking trails were provided with educational signage explaining the BMPs used and the concept for the project. Other site improvements included an entrance road, a 30-car parking facility, picnic tables, benches, and a pavilion shelter. Pollutant discharge from these future improvements is being controlled by minimization of impervious areas, parking lot BMPs including biofiltration swales, and native plant buffers to maximize pollutant filtration and reduction. 

Public recreation is enhanced through a picnic shelter, shoreline piers, ADA-accessible paved trails, and other amenities.
The Jelke Reclamation Project grand opening ceremony engaged hundreds of visitors with a variety of tours, fishing contests, educational booths, workshops, and other activities.

Problems encountered and lessons learned
Reuse of onsite course aggregate materials provides a cost savings for construction of gravel trails. However, aggregate materials along gravel trails had eroded in part in at least some locations. To overcome this, culvert pipes were installed across the gravel trail in locations where concentrated runoff occurred adjacent to the trail. Although it was budgeted, ongoing native plant maintenance will be required to control invasive spurge, thistle, mullein, and other invasive plant species. 

Even though more than 49 rock checks were installed, the initial budget did not allow for rock checks in all steeply sloped areas where they would have been helpful. In some cases, erosion along a tall side slope will require additional rock checks to be installed for long-term stabilization. 

Cobble or larger rock materials were lacking for use as rock checks at the project site. Moreover, the initial budget did not allow for import of rock materials at all areas where they would have been helpful. In this case, erosion along a tall side slope will require rock check installations for long-term stabilization in addition to the wattles previously installed.

Project summary
The 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 log habitat structures;
• 111 acres of native plant seeding; and
• 3.6 miles of walking trails.

Project implementation provided 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. More than $1.3 million in grant funding was obtained for implementation. Total construction costs were approximately $1.76 million. 

The Jelke Creek Restoration Project received the Illinois Association for Floodplain and Stormwater Management Award for Stormwater Project of the Year in 2011. 

Acknowledgements
The project was a cooperative effort funded in part through the Illinois Environmental Protection Agency and the Section 319 Grant Program, and The Open Space Land Acquisition Fund (OSLAD) administered through the Illinois Department of Natural Resources. In addition, the Chicago Metropolitan Agency for Planning provided grant administration. Local watershed support was received from the Fox River Ecosystem Partnership. Engineering services were provided by Living Waters Consultants; construction was provided by G.A. Blocker Grading Inc.; and native plant material installations and maintenance were provided by subcontractor Applied Ecological Services. Dundee Township natural areas staff members continue to maintain the project site. 

Ted Gray, P.E., CFM, CPESC, is an engineer/fluvial geomorphologist with Living Waters Consultants Inc. (www.livingwatersconsultants.com). He can be contacted at 630-261-1133 or tgray@livingwatersconsultants.com.


Upcoming Events

See All Upcoming Events