SOIL CONSERVATION SERVICE 

CONSERVATION PRACTICE 

STANDARD 

 

IMPOUNDMENTS STRUCTURE – FULL FLO 

(no.) 

CODE 841 

 

DEFINITION. A dam or excavation 
which creates an impoundment to 
collect and store debris, sediment, or 
water. 

 

PURPOSE. The purpose of this 
practice is to reduce sediment and/or 
debris in runoff waters to prevent 
damage to downstream facilities; or to 
provide surface water for consumption, 
irrigation, wildlife habitat, recreation or 
fire protection. 

 

CONDITIONS WHERE PRACTICE 
APPLIES. This practice applies where 
sediment or debris are expected to be 
contained in runoff waters and may 
impair the capacity of the watercourse 
or damage other structures or where a 
surface water supply is desirable; where 
storage for at least one (1) inch of 
water from the contributing watershed is 
either impractical or undesirable and 
where any embankment does not 
exceed the limits for Class III, small 
dams, as defined by the IDOT-DWR in 
“Rules for Construction and 
Maintenance of Dams” and the 
landowner or other responsible party 
has secured necessary permits, if 
required, for design and construction 
from IDOT-DWR and any local 
governmental authorities. 

 

 

CRITERIA. 

Investigations. Sufficient investiga-
tions shall be made of the impoundment 
site and borrow areas to determine the 
suitability of site and materials for 
construction, water holding ability and 
structure stability. A complete analysis 
of foundation and proposed fill materials 
shall be made when, in the opinion of 
the responsible engineer, it is 
necessary. 

 

Hazard/Safety. Structures designed 
under criteria found in this practice shall 
fall within the Class III, small dam 
category, defined by the IDOT-DWR as 
follows: “Class III. Dams located where 
failure has low probability for causing 
loss of life, where there are no 
permanent structures for human 
habitation, or minimum economic loss in 
excess of that which naturally would 
occur downstream of the dam if the dam 
had not failed. A dam has a low 
probability for causing loss of life or 
minimal economic loss if it is located 
where its failure may cause damage to 
agricultural fields, timber areas, 
township roads, or similar type areas 
where people seldom are present and 
where there are few structures. This 
corresponds to US Army Corps of 
Engineers Low Hazard Potential and 
USDA SCS class a dams.” 


Small dams have a total impounding 
capacity of less than one thousand 
(1,000) acre-feet and dam height of less 
than forty (40) feet, where dam height 
is defined as “height of dam, in feet, as 
measured from the natural bed of the 
stream or watercourse at the 
downstream dam slope toe of the barrier 
to the top of the embankment or barrier.” 

 

Owners of impoundment structures shall 
obtain all necessary permits. IDOT-
DWR permits may be required for Class 
III, small dams where: 

1. The drainage area of the proposed 
dam is six thousand four hundred 
(6,400) acres or more in a rural area 
or six hundred forty (640) acres or 
more in an urban area, or 

2. The dam is twenty-five (25) feet or 
more in height, provided that the 
impounding capacity is greater than 
fifteen (15) acre-feet, or 

3. The dam has an impounding 
capacity of fifty (50) acre-feet or 
more provided that the dam height is 
greater than six (6) feet. 

 

Pool Capacities. Structures for the 
impoundment of debris or sediment 
shall have a capacity equal to the 
volume of sediment or debris expected 
to be trapped at the site during the 
planned useful life of the structure. That 
capacity may be proportionally reduced, 
if periodic removal of sediment/debris is 
planned. 

 

Structures that impound water for 
consumptive use shall have capacity as 
required by local consumptive use 
standards. 

 

Structures that impound water for 
irrigation, wildlife habitat or recreation 
shall have capacity and depth adequate 
for the intended use. 

 

Structures that impound water for fire 
protection shall have a capacity of at 
least four thousand (4,000) cubic feet 
per residence. That capacity shall exist 
between the inlet to hydrant and an 
elevation three (3) feet below the 
permanent pool elevation. 

 

Runoff Computation. Total runoff 
amounts and peak discharges may be 
computed using procedures found in 
SCS Engineering Field Handbook, SCS 
Engineering Handbook, SCS TR-55 and 
TR-20, US Army Corps of Engineers 
HEC-1 or other procedures designated 
by the appropriate regulatory authorities. 

 

Principal Spillways. Non-permit, IDOT 
Class III dams shall have a principal 
spillway structure capable of passing the 
peak discharge from a twenty-four (24) 
hour duration storm event of frequency 
specified in Table 1 with stage at or 
below emergency spillway crest. 

 

IDOT Class III, permit size dams shall 
have a principal spillway structure 
capable of passing the peak discharge 
from a twenty-four (24) hour, twenty-
five (25) year storm event with stage at 
or below the emergency spillway crest. 

 

Principal spillway structures may be 
conduits, weir-type straight drops, or 
chutes. 


Principal spillway pipe conduits and 
fittings may be metal, as per material 
specifications 551, 552, or 554 or non-
metal, as per SCS material 
specifications 541, 542, 544, or 547. 
Conduits or other materials may be 
used at the discretion of the appropriate 
regulatory authorities. 

 

Pipe conduits should meet the following 
requirements: 

 

The pipe should be capable of 
withstanding external loading without 
yielding, buckling, or cracking. Pipe 
strength should not be less than that of 
the grades indicated in Table 2 for 
plastic pipe and in Table 3 for 
corrugated aluminum and galvanized 
steel pipe. Flexible pipe strength shall 
not be less than that necessary to 
support the design load with maximum 
five percent (5%) deflection. The inlets 
and outlets should be structurally sound 
and made of materials compatible with 
that of the pipe. All pipe joints should be 
made watertight by the use of couplings 
or gaskets or by welding or caulking. 

 

Acceptable pipe materials are cast-iron, 
steel, corrugated steel, or aluminum, 
concrete, plastic, vitrified clay with 
rubber gaskets, and cast-in-place 
reinforced concrete. Aluminum pipe will 
not be used in soils with pH values 
outside the range of 4-9. Concrete and 
vitrified clay pipe should be laid in a 
concrete bedding. Plastic pipe that will 
be exposed to direct sunlight should be 
made of ultraviolet-resistant materials 
and projected by coating or shielding, or 
provisions for replacement should be 
specified. Connections of plastic pipe to 
less flexible pipe or structures must be 
designed to avoid stress concentrations 
that could rupture the plastic. Cantilever 
outlet sections, if used, should be 
designed to withstand the cantilever 
load. Pipe supports should be provided 
when needed. Other suitable outlet 
protection structure devices may also be 
used to provide a safe outlet. 

 

Anti-seep collars should be installed 
around the pipe conduit in the normal 
saturation zone if any of the following 
conditions exist: 

1. The settled dam height exceeds 
fifteen (15) feet. 

2. The conduit is of smooth exterior 
pipe larger than eight (8) inches in 
diameter. 

3. The conduit is of corrugated exterior 
pipe larger than twelve (12) inches 
in diameter. 

 

Anti-seep collars and their connections 
to the pipe should be watertight. The 
collar material should be compatible 
with pipe materials. The maximum 
spacing should be approximately 
fourteen (14) times the minimum 
projection of the collar measured 
perpendicular to the pipe. A minimum of 
one (1) anti-seep collar should be used 
on all conduits. 

 

Closed conduit spillways designed for 
pressure flow must have adequate 
antivortex devices at their inlets. 

 

If needed to prevent clogging of the 
conduit, an appropriate trash guard 
should be installed at the inlet or riser. 


For safety reasons, all vertical drop 
inlets should be constructed to prevent 
accidental injury. This may be 
accomplished by using a horizontal anti-
vortex baffle, trash rack or guard rail. 

 

Procedures for designing, dimensioning, 
and detailing pipe conduit spillways may 
be found in the SCS Engineering Field 
handbook, the SCS National 
Engineering Handbook and Illinois 
Procedures and Standards for Urban 
Soil Erosion and Sedimentation Control 
or other references specified by local 
regulatory authorities. 

 

Weir-type straight drops or box inlets 
and chutes shall be designed according 
to procedures in the SCS Engineering 
Field Handbook, the SCS National 
Engineering Handbook, and the USDA 
Agricultural Handbook No. 301, or as 
specified by the local regulatory 
authorities. 

 

SCS toe wall drop structures can be 
used if the vertical drop is four (4) feet 
or less, flows are intermittent, 
downstream grades are stable, and 
tailwater depth at design flow is equal to 
or greater than one-third (1/3) of the 
height of the overfall. 

 

The ratio of the capacity of drop boxes 
to road culverts shall be as required by 
the responsible road authority. The 
drop box capacity attached to a new or 
existing culvert must equal or exceed 
the culvert capacity at the design flow. 

 

Emergency Spillways. An emergency 
spillway must be provided for each dam, 
unless the principal spillways I large 
enough to pass peak discharge from the 
routed design hydrograph and the trash 
that comes to it without overtopping the 
dam. The following are minimum 
criteria for acceptable use of pipe 
conduit principal spillway without an 
emergency spillway: a conduit with a 
cross-sectional area of three (3) square 
feet or more, an inlet that will not clog, 
and an elbow designed to facilitate the 
passage of trash. 

 

The minimum capacity of a natural or 
constructed emergency spillway shall be 
that required to pass the peak flow 
expected from a design storm of the 
frequency and duration shown in Table 
1. IDOT Class III permit dams shall 
have an emergency spillway capable of 
passing the peak discharge from a 100-
year, 24-hour storm event less principal 
spillway discharge. 

 

Emergency spillways shall provide for 
passing the design flow at a safe 
velocity to a point downstream where 
the dam will not be endangered. 

 

Constructed emergency spillways are 
open channels that usually consist of an 
inlet channel, a control section, and an 
exit channel. They shall be stable for 
the material in which the spillway is to 
be constructed. The emergency 
spillway shall have a bottom width of not 
less than ten (10) feet. 

 

Upstream from the control section, the 
inlet channel shall be level for the 
distance needed to protect and maintain 
the crest elevation of the spillway. The 
inlet channel may be 


curved to fit existing topography. The 
grade of the exit channel of a 
constructed emergency spillway shall 
fall within the range established by 
discharge requirements and permissible 
velocities. Design procedures and 
details for vegetated earth emergency 
spillways may be found in the SCS 
Engineering Field Handbook, the SCS 
National Engineering Handbook, and 
SCS Technical Release 52, or other 
references specified by the local 
regulatory authorities. 

 

Foundation Cutoff. A cutoff of 
relatively impervious material shall be 
provided under the dam if necessary. 
The cutoff shall be located at or 
upstream from the centerline of the 
dam. It shall extend up the abutments 
as required and be deep enough to 
extend into a relatively impervious layer 
or provide for a stable dam when 
combined with seepage control. The 
cutoff trench shall have a bottom width 
adequate to accommodate the 
equipment used for excavation, backfill, 
and compaction operations. Side 
slopes shall not be steeper than one 
horizontal to one vertical. 

Seepage control. Seepage control is to 
be included if: 

1. Pervious layers are not intercepted 
by the cutoff. 

2. Seepage creates swamping 
downstream. 

3. Such control is needed to insure a 
stable embankment. 

4. Special problems require drainage 
for a stable dam. 

 

Seepage may be controlled by: 

1. Foundation, abutment, or 
embankment drains. 

2. Reservoir blanketing. 

3. A combination of these measures. 

 

Earth Embankment. The minimum top 
width for a dam is shown in Table 4. If 
the embankment top is to be used as a 
public road, the minimum width shall be 
sixteen (16) feet for one-way traffic and 
twenty-six (26) feet for two-way traffic. 
Guardrails or other safety measures 
shall be used where necessary and 
shall meet the requirements of the 
responsible road authority. 

 

The combined upstream and 
downstream side slopes of the settled 
embankments shall not be less than five 
horizontal to one vertical, and neither 
slope shall be steeper than two 
horizontal to one vertical. All slopes 
must be designed to be stable, even if 
flatter side slopes are required. 

 

If needed to protect the slopes of the 
dam, special measures, such as berms, 
rock riprap, sand-gravel, soil cement, or 
special vegetation, shall be provided. 

 

The minimum elevation of the top of the 
settled embankment shall be one (1) 
foot above the water surface in the 
reservoir with the emergency spillway 
flowing at design depth. The minimum 
difference in elevation between the crest 
of the emergency spillway and the 
settled top of the dam shall be two (2) 
feet for all dams having more than 
twenty (20) acre drainage area or more 
than twenty (20) feet in effective height. 


The design height of the dam shall be 
increased by the amount needed to 
insure that after settlement the height of 
the dam equals or exceeds the design 
height. This increase shall not be less 
than five percent (5%), except where 
detailed soil testing and laboratory 
analyses show that a lesser amount is 
adequate. 

 

EXCAVATED IMPOUNDMENTS. 

 

Runoff. Provisions shall be made for a 
pipe and emergency spillway if 
necessary. Runoff flow patterns shall 
be considered when locating the pit and 
placing the spoil. 

 

Side Slopes. Side slopes of excavated 
ponds shall be stable and shall not be 
steeper than one horizontal to one 
vertical. 

 

Perimeter Form. If the structures are to 
be used for recreation or are highly 
visible to the public, the perimeter or 
edge should be curvilinear. 

 

Inlet Protection. If surface water 
enters the pond in a natural or 
excavated channel, the side slope of the 
impoundment shall be protected against 
erosion. 

 

Excavated Material. The material 
excavated from the pond shall be placed 
so that its weight will not endanger the 
stability of the pond side slopes and so 
that it will not be washed back into the 
pond by rainfall. It shall be disposed of 
in one of the following ways: 

1. Uniformly spread to a height that 
does not exceed three (3) feet, with 
the top graded to a continuous slope 
away from the impoundment. 

2. Uniformly placed or shaped 
reasonably well, with side slopes 
assuming a natural angle of repose. 
The excavated material will be 
placed at a distance equal to the 
depth of the impoundment but not 
less than twelve (12) feet from the 
edge of the impoundment. 

3. Shaped to a designed form that 
blends visually with the landscape. 

4. Used for low embankment and 
leveling. 

5. Hauled away. 

 

Vegetation. Disturbed areas that are 
not to be cultivated shall be established 
as soon as practicable after 
construction. Seedbed preparation, 
seeding, fertilizing and mulching shall 
comply with practice standard 880 or 
970 Permanent or Temporary Seeding. 

 

CONSIDERATIONS. 

 

Site Safety. Impoundments are 
potential attractive nuisances and safety 
aspects must be considered in their 
design and layout. If the area is used or 
may be used for recreation, it is 
recommended that warning signs be 
erected, that lifesaving equipment be 
available on site and that emergency 
instructions be posted in a conspicuous 
location. 

 

Visual Resource Design. The visual 
design of impoundments shall be 
carefully considered in areas of high 
public visibility and those associated 
with recreation. The underlying criterion 
for all visual design is 


appropriateness. The shape and form 
of ponds, excavated material, and 
plantings are to relate visually to their 
surroundings and to their function. 

 

The embankment may be shaped to 
blend with the natural topography. The 
edge of the impoundment may be 
shaped so that it is generally curvilinear 
rather than rectangular. Excavated 
material can be shaped so that the final 
form is smooth, flowing, and fitting to the 
adjacent landscape rather than angular 
geometric mounds. If feasible, islands 
may be added for visual interest and to 
attract wildlife. 

 

Impoundments for water supply should 
have adequate drainage area to fill at 
least yearly. As a minimum, drainage 
area, in acres, where water supply is a 
primary purpose, shall equal permanent 
storage in acre-feet. 

 

PLANS AND SPECIFICATIONS. Plans 
and specifications for installing full flow 
impoundment structures shall be in 
keeping with this standard and shall 
describe the requirements for installing 
the practice. Items that specifications 
should address, if applicable, and 
appropriate construction/ material 
specifications, standard drawings and 
other standards are as follows: 

 

Site and Foundation Preparation. All 
site and foundation areas shall be 
prepared and maintained in such a 
manner that earthfill placement or other 
specified treatments allow the practice 
to achieve its intended purpose. 
Applicable construction specifications 
may include: 1 CLEARING, 2 
CLEARING AND GRUBBING, 8 
MOBILIZATION, 10 WATER FOR 
CONSTRUCTION, 11 REMOVAL OF 
WATER. 

 

Applicable material specifications may 
include: 521 AGGREGATES FOR 
DRAINFILL FILTERS, 592 
GEOTEXTILES. 

 

Applicable standard drawings may 
include drawing number IL-515 
DIVERSION PLAN, IL-585 EARTH DAM 
STRUCTURE PLAN, IL-630 
STABILIZED CONSTRUCTION 
ENTRANCE, IL-650 SUMP PIT PLAN, 
AND IL-610 TEMPORARY SLOPE 
DRAIN PLAN. 

 

Other applicable standards may include: 
315 DIVERSION, 950 SUMP PIT, 970 
TEMPORARY SLOPE DRAIN, 975 
TEMPORARY STREAM CROSSING. 

 

Excavations and Earthfill. All 
specified excavation shall be preformed 
and earthfills shall be placed in such a 
manner that allows the practice to 
achieve its intended purpose. 
Applicable construction specifications 
may include: 10 WATER FOR 
CONSTRUCTION, 21 EXCAVATION, 
23 EARTHFILL, 24 DRAINFILL, 25 
ROCKFILL, 26 SALVAGING AND 
SPREADING TOPSOIL, 61 LOOSE 
ROCK RIPRAP, 62 GROUTED ROCK 
RIPRAP, 95 GEOTEXTILE. 

 

Applicable material specifications may 
include: 521 AGGREGATES FOR 
DRAINFILL AND FILTERS, 523 ROCK 
FOR RIPRAP, 592 GEOTEXTILE. 


Applicable standard drawings may 
include: IL-585 EARTHDAM 
STRUCTURE PLAN. 

 

Spillway Structures. All spillways 
including inlet and outlet structures shall 
be constructed or installed in a manner 
that allows the practice to achieve its 
intended purpose. Materials and 
construction techniques specified shall 
be appropriate for the intended life and 
hazard classification of the practice. 
Where available, manufacturer’s 
installation recommendations may be 
included in specifications. Application 
construction specifications may include: 
24 DRAINFILL, 25 ROCKFILL, 32 
CONCRETE FOR MINOR 
STRUCTURES, 34 STEEL 
REINFORCEMENT, 41 REINFORCED 
CONCRETE PRESSURE PIPE 
PRINCIPAL SPILLWAY CONDUITS, 42 
CONCRETE PIPE CONDUITS AND 
DRAINS, 43 CLAY PIPE CONDUITS, 
51 CORRUGATED METAL PIPE 
CONDUITS, 41 REINFORCED 
CONCRETE PRESSURE PIPE 
PRINCIPAL SPILLWAY CONDUITS, 42 
CONCRETE PIPE CONDUITS AND 
DRAINS, 43 CLAY PIPE CONDUITS 
AND DRAINS, 51 CORRUGATED 
METAL PIPE CONDUITS, 52 STEEL 
PIPE CONDUITS, 53 DUCTILE-IRON 
PIPE CONDUITS, 61 LOOSE ROCK 
RIPRAP, 62 GROUTED ROCK 
RIPRAP, 64 WIRE MESH GABIONS, 71 
WATER CONTROL GATES, 81 METAL 
FABRICATION AND INSTALLATION, 
83 TIMBER FABRICATION & 
INSTALLATION, 95 GEOTEXTILES. 

 

Applicable material specifications may 
include: 521 AGGREGATES FOR 
DRAINFALL and FILTERS, 522 
AGGREGATES FOR CONCRETE, 523 
ROCK FOR RIPRAP, 531 PORTLAND 
CEMENT, 532 AIR ENTRAINING 
ADMIXTURES, 534 CURING 
COMPOIUND, 535 PREFORMED 
EXPANSION JOINT FILLER, 536 
SDEALING COMPOUND, 537 NON-
METALLIC WATERSTOPS, 538 
METAL WATERSTOPS, 539 STEEL 
REINFORCEMENT, 541 REINFORCED 
CONCRETE PRESSURE PIPE, 542 
CONCRETE CULVERT PIPE, 544 
CLAY PIPE AND CLAY DRAIN TILE, 
546 BITUMINIZED FIBER PIPE, 547 
PLASTIC (PVC, PE, ABS) PIPE, 551 
METALLIC COATED CORRUGATED 
STEEL PIPE, 552 ALUMINUM 
CORRUGATED PIPE, 554 STEEL PIPE 
& FITTINGS, 581 METAL, 582 
GALVANIZING, 584 STRUCTURAL 
TIMBER AND LUMBER, 585 WOOD 
PRESERVATIVES AND TREATMENT, 
592 GEOTEXTILE. 

 

Applicable standard drawings may 
include: IL-543 INLET FOR 
UNDERGROUND OUTLET, IL-545 
CULVERT FLARED END METAL 
SECTION, IL-576 HEADWALL & 
SAFETY GUARD FOR PIPE RISERS, 
IL-577 HOOD INLET WITH BAFFLE 
FOR CMP, IL-578 CMP DROP INLET & 
BAFFLE, IL-579 CMP PIPE 
DIAPHRAGM, IL-580 COUPLING 
BAND FOR CMP, IL-581 TIMBER 
PROP FOR 10” – 30” DIAMETER CMP, 
IL-582 TIMBER PROP FOR 36” – 48” 
DIAMETER CMP, IL-583 DROP INLET 
STRUCTURE PLAN, IL-584 HOOD 
INLET STRUCTURE PLAN, IL-585 
EARTH DAM STRUCTURE PLAN, IL-
586 CMP SUPPORT, IL-590 TRASH 
RACKS FOR PIPE DROP INLET, IL-
591 


TRASH RACKS FOR HOODED INLET, 
IL-592 DETAIL FOR PVC CANOPY 
INLET, IL-593 FLEXIBLE ANTISEEP 
COLLAR, IL-594 CMP WATER 
CONTROL STRUCTURE, IL-610 PIPE 
OUTLET TO FLAT AREA. 

 

Site Physical Protection Plan. 
Adequate measure shall be specified to 
control, on site, additional runoff and/or 
contaminants expected as a result of 
construction activities; to provide for the 
safety of the general public; and to 
provide a maintainable system of 
erosion protection for the constructed 
practice. Applicable construction 
specifications may include: 6 SEEDING, 
SPRIGGING, & MULCHING FOR 
PROTECTIVE COVER, 26 SALVAGING 
& SPREADING TOPSOIL, 27 
DIVERSIONS, 28 WATERWAYS, 46 
TILE DRAINS, 61 LOOSE ROCK 
RIPRAP, 62 GROUTED ROCK 
RIPRAP, 64 WIRE MESH GABIONS, 91 
CHAIN LINK FENCE, 95 
GEOTEXTILES. 

 

Applicable standard drawings may 
include: IL-515 DIVERSION PLAN, IL-
540 WATERWAY PLAN, IL-541 ROCK 
CHECKS FOR WATERWAYS, IL-543 
INLET FOR UNDERGROUND 
OUTLET, IL-595 PORTABLE 
SEDIMENT TANK PLAN, IL-620 SILT 
FENCE PLAN, IL-630 STABILIZED 
CONSTRUCTION ENTRANCE PLAN, 
IL-635 STRAW BALE DIKE PLAN, IL-
615 SEDIMENT BASIN DEWATERING 
PLAN, IL-660 TEMPORARY 
SEDIMENT TRAP. 

 

Other applicable standards may include: 
815 DIVERSION, 820 DIVERSION 
DIKE, 825 DUST CONTROL, 830 
EROSION BLANKET, 835 FILTER 
STRIP, 865 LAND GRADING, 895 
MULCHING, 880 PERMANENT 
SEEDING, 895 PORTLAND SEDIMENT 
TANK, 910 ROCK OUTLET 
PROTECTION, 920 SILT FENCE, 925 
SODDING, 935 STRAW BALE 
BARRIER, 945 SUBSURFACE DRAIN, 
955 TEMPORARY DIVERSION, 960 
TEMPORARY SEDIMENT TRAP, 965 
TEMPORARY SEEDING, 980 
TEMPORARY SWALE, 981 
TOPSOILING. 

 

OPERATION AND MAINTENANCE. 
An operation and maintenance plan 
should be developed and concurred in 
by the owners/operators of the 
impoundment structure. The operation 
plan shall establish a schedule for 
testing all operable facilities to ensure 
that they function as intended, or that 
necessary repairs are made. The 
maintenance plan shall specify 
responsible parties for maintaining or 
replacing, as necessary: all vegetative 
components of the structure, riprap for 
wave protection or outlet protection, inlet 
and outlet works, safety features 
including fences and signs, and on-site 
erosion/water control facilities. 

 

Procedures and responsible parties for 
removing and disposing of accumulated 
debris and/or sediment as necessary to 
ensure the function of the structure shall 
be specified. Procedures and 
responsible parties for repairing damage 
to embankment, spillway structures and 
other appurtenances shall be specified. 
The structure shall be inspected at least 
yearly and after every storm event 


causing flows through vegetated 
spillways or over top of embankment. 

 

If required by the IDOT-DWR, an 
emergency action plan shall be filed for 
permit structures. 

 

SCS IL August 1994 

 

Urb841.dcx