Hobson Creek Corridor Restoration Project, Phase 1%3A Tributary 6 to the East Branch DuPage River%3A Section 319 Project Report

              HOBSON CREEK CORRIDOR RESTORATION PROJECT, PHASE 1
TRIBUTARY 6 TO THE EAST BRANCH DUPAGE RIVER
Section 319 Project Report
Illinois EPA Agreement No. 3190213
Illinois Environmental Protection Agency
Bureau of Water
Watershed Management Section
December 2004
Phase 1 Hobson Creek Corridor Restoration Project Section 319 Final Report 2
HOBSON CREEK CORRIDOR RESTORATION PROJECT, PHASE 1
TRIBUTARY 6 TO THE EAST BRANCH DUPAGE RIVER
SECTION 319 FINAL REPORT
ILLINIOS EPA FAA # 3190213
DECEMBER 2004
Prepared For:
ILLINOIS ENVIRONMENTAL PROTECTION AGENCY
BUREAU OF WATER – WATERSHED MANAGEMENT SECTION
1021 NORTH GRAND AVENUE EAST
SPRINGFIELD, IL 62702
Prepared by:
TED GRAY & ASSOCIATES, INC.
1 SOUTH 132 SUMMIT AVENUE, SUITE 304
OAKBROOK TERRACE, IL 60181
Ph: 630-261-1133 Fax: 630-261-1144
This report was prepared using United States Environmental Protection Agency funds under Section 319
of the Clean Water Act distributed through the Illinois Environmental Protection Agency. The findings
and recommendations contained herein are not necessarily those of the funding agencies.
Phase 1 Hobson Creek Corridor Restoration Project Section 319 Final Report 3
HOBSON CREEK CORRIDOR RESTORATION PROJECT
TABLE OF CONTENTS
Report Section Page #
Summary 4
Introduction 4
Project Schedule 6
Project Description and Stabilization Techniques 6
Restoration of Riparian Corridor 6
Rock Riffle Structures and Stable Channel Construction 7
A-Jacks and Vegetated Geogrid 7
Fiber Roll and Re-Shaped Slopes 8
Rock Placement at Storm Pipe Outfalls 8
Native Plantings 8
Project Costs and Quantities 12
Operation and Maintenance Plan 13
Project Benefits 15
Photos Attachment 1
Project Articles Attachment 2
Land & Water Magazine Sept. / Oct. 2004 Attachment 2
Watershed Currents (by Conservation Foundation) Attachment 2
Phase 1 Hobson Creek Corridor Restoration Project Section 319 Final Report 4
Summary:
The Hobson Creek Community Council completed the Hobson Creek Corridor Restoration Project,
Phase 1 in order to protect against severe streambank erosion, to provide nonpoint source
pollution control along Hobson Creek and to improve water quality of the downstream East
Branch DuPage River. Installed stream stabilization techniques have provided effective and
environmentally sound bank protection and channel stability for the Phase 1 reach. The Hobson
Creek Community Council will provide long-term maintenance for the project site. Public
involvement to date includes awareness of adjacent homeowners, numerous trail and parkway
visitors near existing signage, and publication of three newspaper articles, one environmental
newsletter article, and three professional trade magazine publications.
Introduction:
The Hobson Creek Corridor Restoration Project is located on common space owned by the
Hobson Creek Community Council in unincorporated Naperville, DuPage County, Illinois. A small
portion of the project area is located on private property within the Hobson Creek Community
subdivision where the stream has migrated out of the subdivision common space. Hobson Creek
has a 1.71 square mile watershed. The watershed is primarily comprised of single family and
multi-family residential areas. Hobson Creek has also been identified as Tributary #6 to the
East Branch DuPage River. The East Branch DuPage River is located approximately 1,100 linear
feet downstream of the project site. The entire Hobson Creek Corridor has been divided into 3
reaches for construction implementation purposes:
Phase 1 – Upstream project boundary downstream to stream station 10+00 (Sta. 17+50 to 10+00)
Phase 2 – Stream station 10+00 downstream to Green Trails Drive (Sta. 10+00 to 3+50)
Phase 3 – Green Trails Drive downstream to Woodridge Park District (Sta. 3+50 to 0+00) and
also the Hobson Creek Inlet Channel (additional 250 linear feet)
The Phase 1 project area is the subject of this Final Report. Phase 1 included a 750 linear-foot
length of stream which had severely eroded streambanks and 1.61 acres of degraded riparian
corridor. Severe streambank erosion was due several factors. Most of the watershed was
developed prior to the enforcement of stormwater detention ordinances, resulting in the rapid
discharge of large volumes of urban runoff. The streambank riparian corridor was impacted by
a dense canopy of invasive shrubs including Buckthorn (Rhamnus cathartica) and Honeysuckle
(Lonicera tatarica). The highly eroded streambanks contain little to no ground-stabilizing
vegetation. This provided little functional benefit and contributed to site degradation. The
stream channel had also incised approximately one to two feet into the landscape. Moreover,
significant channel widening has occurred. There are several locations where bank erosion had
forced channel migration out of the common space area into rear yards of individual townhome
units. In some areas the streambanks were within 12 feet of undermining structural home
foundations and within 5 feet of buried utilities. The Illinois EPA Load Reduction Spreadsheet
was utilized to quantify the significant sediment delivery to the East Branch of the DuPage
River as described below under Project Benefits.
Phase 1 Hobson Creek Corridor Restoration Project Section 319 Final Report 5
A primary objective of the Hobson Creek Corridor Restoration Project was to improve the water
quality in the project area and to reduce the sediment loading caused by streambank erosion
into Hobson Creek and the East Branch DuPage River. This objective was accomplished by
extensive streambank stabilization, installation of channel grade control structures, removal of
invasive shrub species in the riparian area, and installation of native plantings along the
stabilized streambanks and within the riparian area.
Location Map
Phase 1 Hobson Creek Corridor Restoration Project Section 319 Final Report 6
Project Schedule
Table 1 below indicates the project schedule and completion requirements. Permits were
received on September 24, 2003. Construction began September 30, 2003 and native planting
installations (native shrub live stakes (and previously herbaceous plant plugs) were completed on
December 9, 2004 according to approved Plans and Specifications.
Table 1: Project Schedule.
Hobson Creek Corridor Restoration Project, Phase 1.
IEPA FAA 3190213.
Action Item Start Date Completion Date *
FAA 3190213 Award Feb. 18, 2003 Feb. 30, 2005
Design Engineering March 1, 2003 May 26, 2003
Permitting May 27, 2003 Sept. 24, 2003
Bidding August 1, 2003 August 20, 2003
Construction Contract Award N/A August 25, 2003
Riparian Invasive Species Removal Sept. 30, 2003 Oct. 15, 2003
Streambank Stabilization Construction Oct. 10, 2003 June 30, 2004
Native Plantings Oct. 15, 2003 Dec. 9, 2004
Project Final Report Jan. 7, 2005
* Items in Bold are expected completion dates.
Project Description and Stabilization Techniques
The Hobson Creek Corridor Restoration Project, Phase 1 included lead engineering, surveying and
drafting by Patrick Engineering, Inc. Stream stabilization design, native planting selection,
construction observation, and maintenance assistance was provided by Ted Gray & Associates,
Inc. Landscape Resources, Inc. provided construction services and will provide a minimum of 3-
years of site maintenance. The best management practices described below were utilized to
restore the riparian corridor and to stabilize the streambanks of the mainstem of Hobson Creek
and the south tributary stream channel (which discharges to mainstem at stream station 16+25).
Restoration of Riparian Corridor
Hobson Creek Corridor Restoration included vegetation management with replacement of 1.61
acres of dense stands on non-native and invasive shrubs and trees (such as Buckthorn) with 45
native tree-shrub clusters, along with native herbaceous species. The replacement of
undesirable vegetation with native species prevents loss of bank soils and promotes bank
stability. This will reduce non-point source pollutant loadings to the downstream East Branch
DuPage River. Replacement of invasive species with native tree and shrub clusters, grasses, and
forbs will also promote filtration and assimilation of nutrients as well as contaminated runoff
that can be discharged from surrounding upland areas. Aquatic habitat along the Hobson Creek
riparian corridor will be enhanced and diversified.
Phase 1 Hobson Creek Corridor Restoration Project Section 319 Final Report 7
Table 2: Streambank Stabilization Practices.
Left Bank Right Bank Total
Stabilization Practice (LF) (LF) (LF)
1-Row A-Jacks / Vegetated Geogrid 0 86 86
3-Row A-Jacks / Vegetated Geogrid 93 355 448
3-Row A-Jacks / Re-Shape Slope 40 0 40
Fiber Roll / Re-Shaped Slope 145 40 185
Rock Riffles (3 @ 25 LF per bank) 75 75 150
Toe-of-Slope Native Plantings Only 80 70 150
Widen Channel / Re-Shape Slope 120 130 250
Rock Placement At Storm Pipe Outfalls 50 20 70
Total (LF) 603 776 1379
Rock Riffle Structures and Stable Channel Construction
Severe channel downcutting has been controlled with installation of rock riffle grade control
structures. Riffles not only control channel downcutting but also dissipate excess stream
energy and reduce extremely high erosive forces against the streambanks. Three (3) rock
riffles were installed in the Phase 1 project area. Materials utilized ranged from 0.5-inch
subsurface gravel to 18-inch surface boulders. The rock riffle structures also diversify and
improve in-stream habitat, diversify stream substrate materials, and enhance aesthetics.
Channel widening was performed in selected areas to re-construct a stable stream channel
configuration in areas which had become severely downcut. Approximately 250 cubic yards of
excavation was performed to re-construct a stable baseflow channel along approximately 250
linear feet of the stream reach.
A-Jacks and Vegetated Geogrid
Streambank stabilization was the most important feature to prevent additional soil pollutant
transport throughout Hobson Creek and the downstream East Branch DuPage River. In the
more severely eroded areas, the streambanks were graded to a flatter slope (excess cut
removed), seeded and planted using native vegetation (described below), stabilized with
vegetated geogrid (Bio-D Block), with toe of slope protection using 1 row or 3 rows of A-jacks.
The permanent A-Jacks structures have a high energy-dissipation capability. The vegetated
geogrid provided biodegradable erosion control along tall slopes as steep as 2.5:1 (H:V). These
techniques were suited for areas that could be stabilized with vegetation alone, such as areas
with high flow velocities along erodible soils, and where high bank shear stresses and sharp
meander bends occur. A-Jacks biotechnical measures were also utilized where the stream
channel migrated out of the common area into private lands and where the erosion threatened
building structures or private properties. Approximately 488 linear feet of 3-rows a-jacks were
installed, as well as 86 linear feet of 1-row a-jacks. All of the a-jacks were installed with bio-d
block vegetated geogrid above the a-jacks with the exception of 40 linear feet of 3-row a-jacks
which were installed with a re-shaped slope.
Phase 1 Hobson Creek Corridor Restoration Project Section 319 Final Report 8
Fiber Roll and Re-Shaped Slopes
Streambanks with moderate erosion were lightly graded back, on a cut-and-fill balance, seeded
and planted with native plant vegetation, covered with an erosion control blanket, with toe
(base) stabilization using coconut (coir) fiber roll. Areas exhibiting only minor erosion were
stabilized by re-shaping bank slopes, seeding and planting with native vegetation, and installing
erosion control blanket. Plant communities were improved by removing the non-native / invasive
vegetation, as well as introducing rooted plant materials. Approximately 185 linear feet of fiber
roll were installed with re-shaped slopes above the fiber roll.
Rock Placement At Storm Pipe Outfalls
Existing storm pipe outfalls were stabilized by re-placing rock that had previously been removed
by the erosive force of the flowing stream. There were two storm pipe outfalls which were
stabilized using rock. The left bank contained a storm pipe outlet near stream station 14+75.
This pipe contained a 25-foot long outlet ditch leading to Hobson Creek. The pipe outfall and
ditch were stabilized by installing a rock toe, re-shaped slopes, and shrub live stakes along 50
linear feet which includes both banks of the outfall ditch. The right bank at stream station
11+90 contained a storm pipe outfall which previously contained little to no rock protection. This
outfall was stabilized using a rock wall over 20 linear feet in length that was built up to the
height of the top of the outfall pipe. The total length of streambank protected by rock
placement near storm pipe outfalls was 70 linear feet.
Native Plantings
Proper selection and installation of native plantings and seed is instrumental to project success.
Native seed and plantings were installed along all stabilized streambank areas. Effective native
plant installations improve long-term streambank stabilization, pollutant filtration, wildlife
habitat, dissipation flow energy, and improvement of site aesthetic values. Toe-of-slope (Type
1) native seed and plug lists, and mid-slope to upper slope native seed (Type 2) plug lists are
provided in Tables 3 and 4 below. Native shrub live stakes (cut live stems) were utilized in
shaded areas with high erosive forces (Table 5). Approximately 150 linear feet of stream
channel was stabilized using native plantings alone without other streambank stabilization
treatments. Also, as described above under Restoration of Riparian Corridor, forty-five (45)
native tree-shrub clusters were installed throughout the riparian area. The ball-and-burlap tree
and shrub species used for the tree-shrub clusters are described in Table 6.
Phase 1 Hobson Creek Corridor Restoration Project Section 319 Final Report 9
Table 3. Native Herbaceous Plant Plugs Species List.
Scientific Name Common Name Percent of Total
Type 1 Native Plant Plugs
Acorus calamus Sweet Flag 5%
Andropogon gerardii Big Bluestem 10%
Andropogon scoparius Little Bluestem 5%
Asclepias incarnata Swamp Milkweed 5%
Carex stipata Common Fox Sedge 5%
Elymus virginicus Virginia Wild Rye 3%
Hystrix patula Bottlebrush Grass 3%
Iris virginica Blue Flag Iris 10%
Juncus tenuis Path Rush 5%
Panicum virgatum Switch Grass 14%
Scirpus acutus Hardstem Bulrush 5%
Scirpus cyperinus Wool Grass 5%
Sorghastrum nutans Indian Grass 10%
Spartina pectinata Prairie Cord Grass 10%
Verbena hastata Blue Vervain 5%
100%
Type 2 Native Plant Plugs
Allium cernuum Nodding Wild Onion 3%
Andropogon scoparius Little Bluestem 3%
Aster novae-anglia New England Aster 6%
Ceanothus americanus New Jersey Tea 3%
Echinacea purpurea Purple Coneflower 9%
Elymus canadensis Wild Canada Rye 6%
Elymus virginica Virginia Canada Rye 4%
Eurythronium americanum Trout Lily 3%
Eupatorium maculatum Joe-Pye Weed 5%
Helianthus grosseseratus Sawtooth Sunflower 3%
Juncus tenuis Path Rush 3%
Lobelia cardinalis Cardinal Flower 3%
Lobelia siphilitica Great Blue Lobelia 3%
Monarda fistulosa Bergamont 5%
Panicum virgatum Switch Grass 9%
Parthenium integrifolium Quinine 3%
Pycnanthemum virginianum Mountain Mint 3%c
Ratibida pinnata Yellow coneflower 3%
Solidago speciosa Showy Goldenrod 3%
Solidago patula Swamp Goldenrod 3%
Sporobolous heterolepsis Prairie Dropseed 6%
Tradescantia ohiensis Spiderwort 3%
Trillium erectum Trillium 3%
Zizea aurea Golden Alexander 5%
100%
Phase 1 Hobson Creek Corridor Restoration Project Section 319 Final Report 10
Table 4. Native Plant Seed List.
Scientific Name Common Name Percent of Total
Type 1 Native Plant Seed
Aster laevis Smooth Aster 3%
Aster novae-anglia New England Aster 3%
Andropogon gerardii Big Bluestem 3%
Andropogon scoparius Little Bluestem 5%
Avena sativa Seed Oats 10%
Carex stipata Common Fox Sedge 5%
Elymus canadensis Wild Canada Rye 5%
Elymus virginica Virginia Canada Rye 3%
Gentiana andrewsii Bottle Gentian 3%
Gilardia pulchella Indian Blanket 5%
Iris virginica Blue Flag Iris 5%
Lolium multiflorum Annual Rye 12%
Panicum virgatum Switch Grass 6%
Phlox divartica Blue Phlox 2%
Rudbeckia hirta Black-Eyed Susan 10%
Scirpus acutus Hardstem Bulrush 5%
Sorghastrum nutans Indian Grass 3%
Spartina pectinata Prairie Cord Grass 6%
Tradescantia ohiensis Spiderwort 3%
Verbena hastata Blue Vervain 3%
100%
Type 2 Native Plant Seed
Allium cernuum Nodding Wild Onion 3%
Andropogon scoparius Little Bluestem 6%
Aquilegia canadensis Columbine 3%
Avena sativa Seed Oats 10%
Cassia fasciculata Partridge Pea 3%
Echinacea purpurea Purple Coneflower 5%
Elymus canadensis Wild Canada Rye 5%
Eupatorium perfoliatum Boneset 5%
Lolium multiflorum Annual Rye 10%
Panicum virgatum Switch Grass 9%
Parthenium integrifolium Quinine 5%
Ratibida pinnata Yellow coneflower 5%
Rudbeckia hirta Black-Eyed Susan 8%
Solidago speciosia Showy Goldenrod 5%
Solidago patula Swamp Goldenrod 5%
Sporobolous heterolepsis Prairie Dropseed 5%
Veronica fasciculata Ironweed 3%
100%
Phase 1 Hobson Creek Corridor Restoration Project Section 319 Final Report 11
Table 5. Native Shrub Live Stakes.
Scientific Name Common Name Percent of Total
Cornus stolonifera Red-Osier Dogwood 40%
Cornus racemosa Gray Dogwood 10%
Salix Interior Sandbar Willow 20%
Viburnum dentatum Arrowwood Viburnum 15%
Viburnum lentago Nannyberry Viburnum 15%
100%
Table 6. Native Tree-Shrub Clusters.
Scientific Name Common Name Percent of Total
Trees
Juglans nigra Black Walnut 25%
Platanus occidentalis American Sycamore 25%
Tilia americana Basswood 25%
Quercus bicolor Swamp White Oak 25%
100%
Shrubs
Cephalanthus occidentalis Button Bush 25%
Cornus stolonifera Red-Osier Dogwood 15%
Salix Interior Sandbar Willow 15%
Sambucus canadensis Elderberry 15%
Viburnum dentatum Arrowwood Viburnum 15%
Viburnum lentago Nannyberry Viburnum 15%
100%
Phase 1 Hobson Creek Corridor Restoration Project Section 319 Final Report 12
Project Costs and Quantities
A summary of quantities and costs are listed below.
Table 7: Summary of Quantities.
BASE BID SCHEDULE OF QUANTITIES AND PRICES
Item No. Stream Restoration Practice Quantity Units Unit Cost Extended Cost
1 Selective Removal of Invasive Species 1.61 ACRES $7,000.00 $11,270.00
2 Tree Removal, 6" to 12" Diameter 8 EA $121.00 $968.00
3 Tree Removal, Over 12" Diameter 3 EA $240.00 $720.00
4 Rock Riffle Structures 3 EA $2,888.00 $8,664.00
5 Fiber Roll 185 LF $34.00 $6,290.00
6 1-Row A-Jacks 81 LF $46.00 $3,726.00
7 3-Row A-Jacks 488 LF $86.00 $41,968.00
8 Vegetated Geogrid (Bio-D Block) 1064 LF $30.00 $31,92.00
9 Re-Shaped Slope / Erosion Control Blanket 311 LF $26.00 $8,086.00
10 Excavation of Stable Baseflow Channel 250 CY $38.00 $9,500.00
11 Rip-rap Installation 9 CY $185.00 $1,665.00
12 Native Tree / Shrub Clusters in Riparian Corridor 45 EA $217.00 $9,765.00
13 Native Shrub Live Stakes (3 per 1 LF) 140 LF $23.00 $3,220.00
14 Native Shrub Live Stakes (1 per 6 LF) 70 LF $2.00 $140.00
15 Native Plant Plugs (2-in. potted plants) at 2 per 1 LF 70 LF $6.00 $420.00
16 Post-Project Construction Fence 500 LF $2.00 $1,000.00
17 Erosion Control & Maintenance 1 LS $4,263.00 $4,263.00
18 Rooftop Downspout Management 1 LS $3,600.00 $3,600.00
19 Project Signs 2 EA $1,572.00 $3,144.00
20 Construction Access & Restoration 1 LS $1,592.00 $1,592.00
21 3-Year Vegetative Perf. Standards and Guarantee 1 LS $12,198.00 $2,439.60
CO001 Outfall Structure Rip-rap & re-shaping 1 LS $1,271.49 $1,271.49
CO002 Decale for Signs 2 LS $50.00 $100.00
CO003 Wildflower Seeding 1 LS $957.00 $957.00
Total $156,689.09
ITEMS AS ORDERED BY ENGINEER
IAOE # Stream Restoration Practice Quantity Units Unit Cost Extended Cost
3a 1-Row A-Jacks 5 LF $46.00 $230.00
3d Re-Shaped Slope / Erosion Control Blanket 14 LF $26.00 $364.00
Total $594.00
Total Contractor Costs to Date: $157,283.09
Phase 1 Hobson Creek Corridor Restoration Project Section 319 Final Report 13
Table 8: Project Cost Summary.
Hobson Creek Corridor Restoration Project, Phase 1.
IEPA FAA 3190213.
Project Cost Summary Total Cost Local Match Grant Assistance
to Date Share Amount
Clerical $0.00 $0.00 $0.00
Supervisor $0.00 $0.00 $0.00
DIRECT LABOR $0.00 $0.00 $0.00
Fringe Benefits $0.00 $0.00 $0.00
Overhead Costs $0.00 $0.00 $0.00
INDIRECT COSTS $0.00 $0.00 $0.00
EQUIPMENT, MATERIALS, SUPPLIES $0.00 $0.00 $0.00
Engineering $48,629.47 $19,451.79 $29,177.68
Permit Fees & Legal Fees $10,786.34 $4,314.54 $6,471.80
Streambank Stabilization $157,283.09 $95,759.58 $61,523.51
SUBCONTRACTS $216,698.90 $119,525.90 $97,173.00
Totals $216,698.90 $119,525.90 $97,173.00
IEPA Grant Award: $107,970.00
Balance of Award: $10,797.00
Operation and Maintenance Plan
Maintenance of native plantings along the stabilized streambanks and within the riparian
corridor is critical to project success. The Hobson Creek Community Council will take
responsibility for the EPA Section 319 grant 10-year Operations & Maintenance agreement for
streambank bioengineering protection measures and plant maintenance. The following are
provisions for this Agreement.
Bioengineering Materials Inspections
Bioengineering materials inspections for the constructed streambank stabilization area will
occur at least two times per year according to the attached schedule in Table 9. Repairs will be
made as necessary, as determined by the Owner and their designated Representative.
Phase 1 Hobson Creek Corridor Restoration Project Section 319 Final Report 14
1. A-Jacks: Inspections will occur for dislodgement or relocation of A-Jacks components if any,
broken pieces, or other indications of potential stabilization concerns.
2. Fiber Roll: Inspections will occur for the staking, undercutting, cord fasteners, and integrity
of the Fiber Roll.
3. Rock Riffles: Some rock displacement at the riffles is expected, but significant relocation
of larger rock materials is not desirable. Major relocation of rock will be inspected and
noted.
4. Re-Shaped Slopes and Vegetated Geogrid: The performance of the re-shaped slopes and
vegetated geogrid to stabilize the site slopes will be inspected. Growth of vegetation and
locations requiring additional planting will be inspected. Eventually, the vegetated geogrid will
biodegrade presumably within a few years. The capability of plantings to stabilize the
resulting angle of repose will be noted.
Native Plant Maintenance
Conditions will be monitored and maintenance will be performed as described in the attached
schedule. Native plant maintenance will occur using spot herbicide applications, hand removal of
nuisance weeds, and related activities performed at least three times per year per the attached
schedule. Non-native species will be removed from the streambank stabilization area.
Maintenance Costs
We estimate that the annual site maintenance budget will be approximately $5,000 annually,
primarily to control re-introduced invasive species such as Buckthorn (Rhamnus cathartica), and
Tartarian Honeysuckle (Lonicera tatarica) from taking over the newly establishing native plants.
Expenditures may be higher expenditures during the first three years for native plant
maintenance and nuisance weed control as the native plantings become established. Costs for
Operations and Maintenance shall be paid by the Owner, the Hobson Creek Community Council.
Table 9. Site Maintenance Schedule.
Post-Construction through 2012
Activity late March mid-May mid-June mid-July mid-August
Mow and/or Cut Natives X
Spot Herbicide / Remove Weeds X X X
Bioengineering Materials Inspection X X
Responsibilities
The Hobson Creek Community Council Board and their designated Representative shall be
responsible for project site maintenance. Participating parties will include the Owner’s
Representative, professional Contractor services support, or possibly volunteers of the Hobson
Creek Community.
Phase 1 Hobson Creek Corridor Restoration Project Section 319 Final Report 15
Project Benefits
Water Quality
Most of the Phase 1 streambank stabilization construction was completed by December 15,
2003. Final planting installations were completed by December 9, 2004. We observed rapid
establishment of temporary cover crop following slope stabilization. Despite significant rainfall
events in June 2004, the banks remained protected and erosion was greatly reduced. Selected
replacement of invasive trees and shrubs with native species in the 1.61-acre riparian area will
also substantially reduce the loss of bank soils and promote bank soils stability. Native riparian
plantings will substantially not only reduce sheet erosion but also mass wasting within the region.
This will significantly reduce non-point source pollutant loadings to the downstream East Branch
DuPage River. Based on site observations, there is minimal sediment delivered to the stream
from the restoration site.
The Illinois EPA Load Reduction Spreadsheet was used to calculate pollutant loading rates from
the project site. Input data included a combined streambank (left and right bank) length of
1,379 linear feet (see Table 2). We included 794 linear feet of severe erosion with a bank
height of 5 feet and an erosion rate of 0.55 ft/yr. We also included 585 linear feet of
moderate streambank erosion with a bank height of 3 feet and an erosion rate of 0.40 ft/yr.
Based on these assumptions, the project site had previously contributed approximately 115 tons
of sediment, 115 pounds of phosphorus, and 231 pounds of nitrogen annually to Tributary # 6.
These estimates do not include historic sediment loss due to severe channel downcutting which
has also occurred at this site. Due to stream stabilization, these pollutant loading rates to
Hobson Creek have been dramatically reduced at the project site.
Habitat and Riparian Function
• Selected replacement of invasive species with native tree and shrub clusters, grasses, and
forbs will protect and diversify wildlife habitat corridor along Hobson Creek, as well as
diversity the native plant understory which is an indicator of a healthy ecosystem. The
proposed plant species will also increase the diversity of foraging opportunities for wildlife.
Significant amounts of dead woody debris in the riparian corridor were not removed, as this
provides habitat for invertebrates, amphibians, birds, and mammals.
• Selected removal of invasive species will allow more desirable and beneficial species to
flourish. There were numerous impacts to ecological integrity caused by the previously
existing invasive plant species in the riparian zone. Dense stands of invasive shrubs such as
common buckthorn and Tartarian honeysuckle previously shaded and out-competed growth of
seedlings of black walnut (Juglans nigra) and bur oak (Quercus macrocarpa) which occur in
limited number in the riparian area. Indeed, few seedlings of these desirable tree species
were previously observed in the existing riparian area. Riparian restoration will increase
sunlight penetration and increase the density of desirable tree and shrub species.
Phase 1 Hobson Creek Corridor Restoration Project Section 319 Final Report 16
• The proposed riparian planting restoration will enhance the function of interception of
rainfall. Deep-rooted trees and plants have increased absorption properties over the
existing riparian species.
• The proposed density of trees, shrubs, forbs and grasses will enhance pollutant filtration
and assimilation of nutrients as well as contaminated runoff discharged from surrounding
upland areas, or through the project site. Native groundcover such as grasses and forbs are
particularly efficient at trapping sediment in the uptake of phosphorus and nitrogen
nutrients which otherwise cause pollution within the waterway. The proposed planting plan
will significantly increase the abundance of groundcover species. Deep-rooted trees will
increase the uptake of nitrogen from shallow groundwater, improving water quality of the
stream.
• The proposed planting plan will help restore in-stream vegetative cover by encouraging
partial sunlight penetration into the water column to enhance growth of shoreline forbs and
grasses, as well as potentially allowing in-stream aquatic macrophytes. This will enhance the
function of in-stream habitat conditions.
Public Outreach / Education
Project Signage (per project plans) placed at strategic locations at Green Trails Drive and at
Green Briar Drive are being utilized to notify motorists, pedestrians, and visitors regarding the
project, funding sources, and proposed improvements and activities. The project site adjoins a
walking trail and outdoor athletic facilities at Seven Bridges Park owned by the Woodridge Park
District that receives thousands of visitors annually. This park is located immediately
downstream of Green Trails Drive. In addition, Caddy Corner Park is located adjacent to the
upstream end of the project site, along the Hobson Creek corridor. Many of these park visitors
use trails and sidewalks along the Hobson Creek stream corridor which will further enhance
community educational outreach from the project site.
The Hobson Creek Community Council (HCCC) Board and members have been active over the last
several years in acquiring Phase 1 Section 319 Clean Water Act grant funding through the
Illinois EPA and U.S. EPA, acquiring DuPage County Water Quality Improvement Program
funding, completing final engineering design, obtaining regulatory permit approvals for the
Phase1 and Phase 2 project areas, educating homeowners, acquiring landowner signoffs for the
proposed work in the common area, setting aside matching funds to complete portions of this
project, contracting with stream consultants, and other activities. Over 20 landowners along
the project site have been contacted by HCCC regarding the project for easement agreements
associated with the proposed work. Additional HCCC education includes Board meetings,
quarterly newsletter updates, and announcements in meetings of the Conservation Foundation.
According to Mr. Bob Longacre of HCCC, in part as a result of these efforts and a successful
project, the residents of HCCC have been pleased with the project results to date.
Phase 1 Hobson Creek Corridor Restoration Project Section 319 Final Report 17
Various newsletter, newspaper and periodical articles have been published regarding the Hobson
Creek Corridor Restoration Project. The Conservation Foundation newsletter Watershed
Currents published a project article in 2003, Vol. 2, Issue 2. Three newspaper articles have
been published regarding the project. Meg Dedolph published “Homeowners Work to Restore
Creek” in The Naperville Sun in mid-November, 2003. A letter to the editor of the Naperville
Sun was published in response to the newspaper article was submitted by the Commissioner of
the Forest Preserve District of DuPage County, entitled “Hobson Creek Restoration Lifts
Quality of Life.” One pre-construction newspaper article was published in the Daily Herald,
Section 1. This newspaper article was entitled “Your Actions May Be Key to Water Quality,
County Says.” One professional publicist published three professional journal articles featuring
the Hobson Creek Corridor Restoration Project. An article entitled “Hobson Creek Restoration
Project” was published in the November / December 2004 Land & Water Magazine by Greg
Northcutt including interviews with Ted Gray. An article entitled “Stable Streams” was
published by Mr. Northcutt in December 2004 Civil Engineering News Magazine. November
2004. An article titled “Stabilizing an Urban Streambank” was published by Mr. Northcutt in
the November, 2004 Landscape Architect and Specifier News.
Phase 1 Hobson Creek Corridor Restoration Project Section 319 Final Report 18
ATTACHMENT 1: PROJECT PHOTOS
Phase 1 Hobson Creek Corridor Restoration Project Section 319 Final Report 19
ATTACHMENT 2: PROJECT ARTICLES
A) LAND & WATER MAGAZINE SEPT./ OCT. 2004
B) WATERSHED CURRENTS (CONSERVATION FOUNDATION)