HOBSON CREEK CORRIDOR RESTORATION PROJECT, PHASE 2
TRIBUTARY 6 TO THE EAST BRANCH DUPAGE RIVER
Section 319 Project Report
Illinois EPA Agreement No. 3190325
Illinois Environmental Protection Agency
Bureau of Water
Watershed Management Section
November 2005
Phase 2 Hobson Creek Corridor Restoration Project Section 319 Final Report 2
HOBSON CREEK CORRIDOR RESTORATION PROJECT, PHASE 2
TRIBUTARY 6 TO THE EAST BRANCH DUPAGE RIVER
SECTION 319 FINAL REPORT
ILLINIOS EPA FAA # 3190325
NOVEMBER 2005
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 2 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 2 Hobson Creek Corridor Restoration Project Section 319 Final Report 4
Summary:
The Hobson Creek Community Council completed the Hobson Creek Corridor Restoration Project,
Phase 2 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 2 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, a project description and site tour for the River Restoration
Principles and Practices Conference sponsored by IL-IN Sea Grant, 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. 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 2 project area is the subject of this Final Report. Phase 2 included a 650 linear-foot
length of stream which had severely eroded streambanks and 1.31 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 has incised approximately one to two feet into the landscape, particularly the
upstream portion of the project reach. Moreover, significant channel widening has occurred.
There is one location in the Phase 2 project reach (Station 6+00) where streambank erosion is
within 10 feet of migrating out of the common open space area into private property of the
adjacent townhome structures. Several large trees have nearly fallen into the eroding stream
channel. The severe streambank erosion has resulted in significant sediment delivery to the
East Branch of the DuPage River. Moreover, the streambank riparian corridor has become
Phase 2 Hobson Creek Corridor Restoration Project Section 319 Final Report 5
encroached with a dense canopy of invasive, exotic shrubs including Buckthorn (Rhamnus
cathartica). This has provided little functional benefit to the site, and has contributed to site
degradation as discussed below (under Proposed Stabilization Plan). 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.
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 a channel grade control structure, 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
Project Site
Phase 2 Hobson Creek Corridor Restoration Project Section 319 Final Report 6
Project Schedule
Table 1 below indicates the project schedule and completion requirements. Permits for the
Phase 1 and Phase 2 Project Sites were received on September 24, 2003. Phase 2 project
construction began September 20, 2004 and native planting installations (native shrub live
stakes and herbaceous plant plugs) were completed June 2, 2005 according to approved Plans
and Specifications.
Table 1: Project Schedule.
Hobson Creek Corridor Restoration Project, Phase 2.
IEPA FAA 3190325.
Action Item Start Date Completion Date *
FAA 3190325 Award May 1, 2004 April 30, 2006
Design Engineering March 1, 2003 May 26, 2003
Permitting May 27, 2003 Sept. 24, 2003
Bidding August 1, 2004 August 19, 2004
Construction Contract Award N/A August 20, 2003
Riparian Invasive Species Removal Sept. 20, 2004 Oct. 15, 2004
Streambank Stabilization Construction Oct. 10, 2004 Oct. 25, 2004
Native Plantings Oct. 15, 2004 June 2, 2005
Project Final Report Dec. 15, 2005
* Items in Bold are expected completion dates.
Project Description and Stabilization Techniques
The Hobson Creek Corridor Restoration Project, Phase 2 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 was contracted to provide a
minimum of 3-years of site maintenance. However, Landscape Resources, Inc. (LRI) declared
bankruptcy in fall 2005. Therefore, HCCC is currently seeking Performance Bond payment for
native plant maintenance services from the insurance carrier that was contracted by LRI. The
best management practices described below were utilized to restore the riparian corridor and
to stabilize the streambanks of the mainstem of Hobson Creek.
Restoration of Riparian Corridor
Hobson Creek Corridor Restoration included vegetation management with replacement of 1.31
acres of dense stands on non-native and invasive shrubs and trees (such as Buckthorn) with 44
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
Phase 2 Hobson Creek Corridor Restoration Project Section 319 Final Report 7
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.
Table 2: Streambank Stabilization Practices.
Left Bank Right Bank Total
Stabilization Practice (LF) (LF) (LF)
1-Row A-Jacks / Vegetated Geogrid 80 0 80
3-Row A-Jacks / Vegetated Geogrid 0 75 75
Fiber Roll / Re-Shaped Slope 50 0 50
Fiber Roll / Vegetated Geogrid 100 130 230
Rock Riffles (1 @ 25 LF per bank) 25 25 50
Re-Shaped Slope / Native Plantings 29 27 56
Toe-of-Slope Native Plantings Only 0 175 175
Rock Placement At Storm Pipe Outfalls 15 0 15
Total (LF) 299 432 731
Rock Riffle Structure
Channel downcutting has been controlled with the installation of one (1) rock riffle grade control
structure. The constructed riffle structure not only controls and prevents further channel
downcutting but also dissipates excess stream energy and reduces extremely high erosive
forces against the streambanks. 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.
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. Approximately 75 linear feet of 3-rows a-jacks were installed, as well as
80 linear feet of 1-row a-jacks. All of the a-jacks were installed with bio-d block vegetated
geogrid above the a-jacks.
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
Phase 2 Hobson Creek Corridor Restoration Project Section 319 Final Report 8
(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 280 linear feet of fiber
roll were installed with re-shaped slopes above the fiber roll.
Rock Placement At Storm Pipe Outfall
One existing storm pipe outfall was stabilized by re-placing rock that had previously been
removed by the erosive force of the flowing stream. The left bank contained a storm pipe
outlet near stream station 5+50. The pipe outfall was stabilized by installing a rock toe. The
total length of streambank protected by rock placement near storm pipe outfall was 15 linear
feet.
Re-Shaped Slope / Native Plantings
Areas exhibiting low 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 56 linear feet of re-shaped slopes were installed with native plantings.
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 175 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-four (44)
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 2 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 4%
ASCLEPIAS INCARNATA MARSH MILKWEED 2%
ASTER SIMPLEX MARSH ASTER 2%
CAREX EMORYII RIVERBANK TUSSOCK SEDGE 5%
CAREX JAMESII GRASS SEDGE 3%
CAREX SPARGANOIDES BURRED SEDGE 1%
CAREX STIPATA COMMON FOX SEDGE 2%
CAREX VULPINODEA FOX SEDGE 2%
HYSTRIC PATULA BOTTLEBRUSH GRASS 2%
IRIS VIRGINICA BLUE FLAG IRIS 5%
JUNCUS TORREYI TORREY'S RUSH 1%
LEERSIA ORYZIODES RICE CUTGRASS 2%
PANICUM VIRGATUM SWITCHGRASS 10%
100%
Type 2 Native Plant Plugs
ALLIUM CERNUM NODDING WILD ONION 2%
ANDROPOGON GERARDII BIG BLUESTEM 2%
AQUILEGIA CANADENSIS COLUMBINE 3%
ASTER CORDIFOLIUS HEART-LEAVED BLUE WOOD ASTER 2%
ASTER LATERIFLORUS SIDE-FLOWERING ASTER 2%
ASTER NOVAE-ANGLIAE NEW ENGLAND ASTER 2%
CEANOTHUS AMERICANUS NEW JERSEY TEA 3%
ECHINACIA PURPURIA PURPLE CONEFLOWER 5%
ELYMUS CANADENSIS PRAIRIE WILD RYE 3%
ELYMUS VIRGINICUS VIRGINIA WILD RYE 3%
EUPATORIUM PURPUREUM SWEET JOE-PYE WEED 1%
GERANIUM MACULATUM WILD GERANIUM 2%
HELIANTHUS GROSSESERATUS SAWTOOTH SUNFLOWER 5%
LOBELIA CARDINALIS CARDINAL FLOWER 1%
LOBELIA SIPHILITICA GREAT BLUE LOBELIA 3%
PENSTEMON CALYCOSUS SMOOTH PENSTEMON 3%
PENSTEMON DIGITALIS FOXGLOVE PENSTEMON 3%
PYCNANTHEMUM VIRGINIANUM MOUNTAIN MINT 1%
SOLIDAGO OHIENSIS OHIO GOLDENROD 3%
SOLIDAGO GIGANTEA LATE GOLDENROD 2%
SOLIDAGO PATULA SWAMP GOLDENROD 1%
SOLIDAGO SPECIOSA SHOWY GOLDENROD 3%
SPARTINA PECTINATA PRAIRIE CORD GRASS 4%
100%
Phase 2 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-ANGLIAE NEW ENGLAND ASTER 3%
ANDROPOGON GERARDII BIG BLUESTEM 3%
ANDROPOGON SCOPARIUS LITTLE BLUESTEM 5%
AVENA SATIVA SEED OATS 10%
CAREX VULPINOIDEA FOX GRASS 3%
CAREX STIPATA COMMON FOX SEDGE 5%
ELYMUS CANADENSIS CANADA WILD RYE 5%
ELYMUS VIRGINICUS VIRGINIA WILD 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 6%
SCIRPUS ACUTUS HARDSTEM BULRUSH 6%
SORGHASTRUM NUTANS INDIAN GRASS 3%
SPARTINA PECTINATA PRAIRIE CORD GRASS 6%
TRADESCANTIA OHIENSIS SPIDERWORT 3%
VERNENA 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%
ELYMUS VIRGINICUS VIRGINIA WILD RYE 6%
EUPATORIUM PERFOLIATUM BONESET 4%
LOLIUM MULTIFLORUM ANNUAL RYE 10%
PANICUM VIRGATUM SWITCH GRASS 6%
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%
VERONIA FASCICULATE IRONWEED 3%
100%
Phase 2 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
Acer nigrum Black Maple 5%
Catalpa speciosa Catalpa 20%
Platanus occidentalis American Sycamore 25%
Quercus bicolor Swamp White Oak 25%
Quercus macrocarpa Burr 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 2 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
Quantit
y Units Unit Cost
Extended
Cost
1 Selective Removal of Invasive Species 1.31 ACRES $8,216.00 $10,762.96
2 Tree Removal, 6" to 12" Diameter 11 EA $128.00 $1,408.00
3 Tree Removal, Over 12" Diameter 2 EA $407.00 $814.00
4 Rock Riffle Structures 1 EA $3,362.00 $3,362.00
5 Fiber Roll 280 LF $35.00 $9,800.00
6 1-Row A-Jacks 80 LF $52.00 $4,160.00
7 3-Row A-Jacks 73 LF $95.00 $6,935.00
8 Vegetated Geogrid (Bio-D Block) 696 LF $32.00 $22,272.00
9 Re-Shaped Slope / Erosion Control Blanket 56 LF $28.00 $1,568.00
11 Rip-rap Installation 5 CY $249.00 $1,245.00
12 Native Tree / Shrub Clusters in Riparian Corridor 48 EA $314.00 $15,072.00
15 Native Plant Plugs (2-in. potted plants) at 2 per 1 LF 175 LF $6.20 $1,085.00
15 Native Plant Plugs 200 EA $3.10 $620.00
18 Rooftop Downspout Management 1 LS $1,385.00 $1,385.00
16 Post-Project Construction Fence 390 LF $2.30 $897.00
17 Erosion Control & Maintenance 1 LS $4,390.00 $4,390.00
20 Construction Access & Restoration 1 LS $2,088.00 $2,088.00
Owners and Contractors Insurance Policy 1 LS $2,575.00 $2,575.00
21 3-Year Vegetative Perf. Standards and Guarantee 1 LS
$12,368.0
0 $2,473.60
C01 Rip-rap credit on a-jacks 2 EA ($495.00) ($990.00)
C02 Bio D changed to erosion blanket 1 LS ($684.00) ($684.00)
C03 Black plastic pipe replaced PVC 1 LS ($885.00) ($885.00)
C04 Additional stone credit on rip-rap 1 EA ($450.00) ($450.00)
C05 Outlet Pipe Repair 1 LS $1,130.00 $1,130.00
C06 Wildflower seeding & blanket 1 LS $300.00 $300.00
C07 Credit for plantings 1 LS ($2,887.09) ($2,887.09)
Total $88,446.47
Total Contractor Costs to Date: $88,446.47
Phase 2 Hobson Creek Corridor Restoration Project Section 319 Final Report 13
Table 8: Project Cost Summary.
Hobson Creek Corridor Restoration Project, Phase 2.
IEPA FAA 3190325.
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 $31,517.50 $13,207.00 $18,310.50
Streambank Stabilization $82,797.20 $35,970.70 $46,826.50
SUBCONTRACTS $114,314.70 $49,177.70 $65,137.00
Totals $114,314.70 $49,177.70 $65,137.00
IEPA Grant Award: $72,374.00
Balance of Award: $7,237.00
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 2 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 riffle 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. Tree / shrub clusters which contain dead trees will be replaced according to the 3-
year Vegetative Performance Standards in the Specifications plan sheet. 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 2013
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 2 Hobson Creek Corridor Restoration Project Section 319 Final Report 15
Project Benefits
Water Quality
Most of the Phase 2 streambank stabilization construction was completed by October 25, 2004.
Final planting installations were completed by June 2, 2005. We observed rapid establishment
of temporary cover crop following slope stabilization. The banks remained protected and
erosion was greatly reduced. However, severe drought conditions through summer 2005
necessitated watering of streambank plantings to prevent a reduction in vegetative coverage.
Several site watering applications were performed by Hobson Creek Community Council and the
Contractor which helped to maintain vegetative growth. Selected replacement of invasive trees
and shrubs with native species in the 1.31-acre riparian area will also substantially reduce the
loss of bank soils and promote bank soils stability. Native riparian plantings will reduce sheet
erosion and mass wasting within the flood zone. 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 450 linear feet of severe erosion with a bank
height of 5 feet and an erosion rate of 0.55 ft/yr. We also included 281 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 53 tons
of sediment, 53 pounds of phosphorus, and 106 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.
Selected dead woody debris in the riparian corridor was 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
Phase 2 Hobson Creek Corridor Restoration Project Section 319 Final Report 16
were previously observed in the existing riparian area. Riparian restoration will increase
sunlight penetration and increase the density of desirable tree and shrub species.
• 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 2 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 Phase
1 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.
Phase 2 Hobson Creek Corridor Restoration Project Section 319 Final Report 17
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.
A project description was presented and a site tour conducted in September 2005 for the River
Restoration Principles and Practices Conference sponsored by IL-IN Sea Grant and hosted at
Illinois Institute of Technology. Ted Gray served as the presenter and tour guide.
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 2 Hobson Creek Corridor Restoration Project Section 319 Final Report 18
ATTACHMENT 1: PROJECT PHOTOS
Phase 2 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)
