Ravine Erosion Control
City of Highland Park , IL
Basin Program Funds:
$49,500 (phase I); $10,000 (phase II)
Highland Park storm sewers empty directly into ravines which then drain into
Lake Michigan. During storm events they produce high speed runoff with short
detention time that create heavy erosion from the ravines.
The City of Highland Park, Illinois, population 34,000, has ten (10) separate
ravines, totaling over eleven (11) miles of channel that drain the eastern third
of the city into Lake Michigan. This watershed is highly urbanized and contains
approximately 2,500 residential, commercial, and retail properties. The separate
ravine drainage basins have impervious surface ratios (square footage of impervious
surface divided by the total area square footage) of 20 percent to 48 percent.
Sanitary sewers were installed in Highland Park 70 to 90 years ago to convey
wastewater to Lake Michigan. Such sewers, along with a large interceptor sewer
which receives and transports the conveyed wastewater to a treatment plant,
are still in use. The construction of the sanitary sewers and other infrastructure
improvements resulted in increased development of surrounding properties for
residential, commercial and retail use. The result of this urbanization in and
near the City of Highland Park has been storm sewers that directly discharge
into the ravine channels at various locations, producing high runoff rates,
short detention times, high peak flows and velocities. The energy produced from
the high flows and velocity have substantially eroded the ravine channel, clay
and silt banks and slope toe leading to slope failures and slumping.
The goal of this project was to construct an in-channel "Gabion"
basket detention basin at a strategically located site to detain the selected
ravine sub-watershed runoff up to a 10 year storm event. This in-channel detention
basin was designed to restrict downstream flow and control erosion from a 3.5
square mile highly urbanized watershed that flows into Lake Michigan. Other
goals of the one year project included verification of the success of the detention
basin with respect to limiting ravine slope and bank erosion and developing
criteria for future ravine stormwater detention projects.
This project was funded in two phases. The first phase was conducted from 1993
through 1995 and included the project design, site selection, and most of the
treatment construction. The second phase, conducted from 1995 through October
1997, involved construction completion, follow-up measurement and testing, and
publication and distribution of results.
Project personnel chose two ravine sites, Lake Bluff and Highland
Park, which were susceptible to rapid erosion and exhibited various stages of
renewed down cutting with associated bank slumping and structural rotary failures.
Lake Bluff Ravine – This ravine is about 3,000 feet long draining directly
into Lake Michigan. The project focused on a 450 foot previously restored section
and another 100 foot unrestored section upstream with an average slope 1:42.
The intent was to augment or reestablish natural stream bed and stream bank
armor. Project personnel graded out stream bed irregularities, laid down geotextile
in slumped areas. These were then filled with quarried limestone cobble and
concrete rubble. The slumps were covered with soil and hydro-seeded with temporary
annual grass in order for natural vegetation to have an opportunity to reestablish
Highland Park Ravine 10 – Interceptor sanitary sewers
installed in some of the ravines appear to have added to increased erosion because
their installation disturbed the natural stream bed armoring from cobble. The
project focused on 900 feet of ravine beginning at its head with an average
slope 1:53. Project personnel utilized several methods for remediating this
ravine section. They built gabion baskets out of galvanized steel mesh, filled
them with 3-6 inch quarried limestone and installed 3X3X9 and 3X3X12 units along
the toes of ravine slopes where erosion was active. They also installed Reno
Mattresses which were constructed like the gabion baskets except they were only
9 inches thick. The Reno Mattresses were installed over geotextile on the base
of the ravine bed. A-Jacks are concrete or plastic structures shaped like a
6-arm toy jack. These were installed at the toe of the ravine slope on either
or both sides of the ravine bed or adjacent to and downstream of a Reno Mattress.
Project personnel then planted willow cuttings between the jacks. Finally geo-web,
a plastic textile which holds cobblestones in place, was used in areas of actively
Project personnel measured the effectiveness of ravine stabilization
in three ways: sediment transport sampling stations, stream bed down cutting
measured with rod and transit, and visual survey. The various techniques showed
different rates of success. Least successful were the A-Jacks and willow plantings
because there was too much erosion and not enough sunlight to enable the willows
to grow. The restored stream bed armor in Lake Bluff exceeded expectations.
Project personnel were able to demonstrate a savings of 13.2 ton/year/100 feet
of restored ravine at the Lake Bluff site. They concluded that the installation
of a continuous layer of streambed armor most closely mimics nature, is the
least expensive solution and is less obtrusive than other methods.
Contact: James H. Johnson, (847) 926-1144