CHAPTER 13 - Design & Construction Standards for Sediment and Erosion Control
13.01 Introduction
13.02 Applicability
13.03 Design Standards
13.04 Temporary Storm Water Control Measures
13.05 Temporary Ground Surface
13.06 Permanent Ground Surface
13.07
Standard Details
13.01 INTRODUCTION
The intent of this section is to require erosion control and storm water practices that will reduce the amount of sediment and other pollutants leaving development sites, both during and after construction and reduce the impact of development on erosion in receiving streams. It is also the intent of the section to promote design and construction practices that 1) minimize ground disturbances during development; 2) maintain natural drainage and 3) provide storm water storage. Erosion, sediment, and storm water control measures are needed for the following reasons:
- High rates of soil loss may occur from areas undergoing
development for nonagricultural use including, but not limited
to, the construction of dwelling units, commercial buildings,
industrial plans, and public works.
- The washing, blowing and falling of eroded soil across and
upon roadways endangers the health and safety of users thereof
by decreasing vision and reducing traction of road vehicles.
- Soil erosion necessitates the costly repair of gullies,
washouts, embankments, drainage structures, and stream banks.
- Sediment from soil erosion can clog or reduce the flow and
storage capacity of sewers, ponds, ditches, and streams.
- Sediment and associated pollutants can pollute the waters
of streams, ponds, lakes, and rivers, creating far-reaching
biological impacts to aquatic life and species dependent upon
aquatic life.
- Sediment limits the use of water and waterways for beneficial
uses, including water supply, navigation, recreation, fishery
resources, drainage, and flood control.
- Development, if not controlled, causes increases in peak
storm water runoff rates which can lead to increased stream
bed and stream bank erosion and flooding in receiving streams.
- Erosion and stream bank instability caused by altered stream
flow rates due to development can create unsafe conditions,
adverse environmental impacts, and other conditions that require
costly repairs or preventative measures to protect private and
public structures and facilities.
- To meet the requirements of the Federal Water
Pollution Control Act Amendments of 1972,1977, and
subsequent amendments, commonly known as the Clean Water
Act.
- To comply with the City of Normal Storm Water Management Plan.
13.02 APPLICABILITY
- No person shall commence or perform any clearing,
grading, stripping, excavating, or filling of land which
meets the following provisions unless an Erosion and
Sediment Control Permit has first been obtained for that
activity from the Engineering Department:
- Any land disturbing activity (i.e., clearing,
grading, stripping, excavating, fill, or any
combination thereof) that will affect an area in
excess of 5,000 square feet; or
- Any land disturbing activity that will affect an
area in excess of 1,000 square feet if the activity
is within 25 feet of a lake, pond, stream, or
wetland; or
- Excavation, fill or any combination thereof that
will exceed 100 cubic yards.
- Any land disturbing activity (i.e., clearing,
grading, stripping, excavating, fill, or any
combination thereof) that will affect an area in
excess of 5,000 square feet; or
- A permit shall not be required for any of the
following provided that the person responsible for any
such development shall implement necessary soil erosion
and sediment control measures to satisfy the principles
set forth in section 6.2 of Chapter 24 of City Code and
in this Manual:
- Excavation below final grade for the basement and footings of one (1) single family residence and appurtenant structures on a site in excess of five (5) acres, which disturbs less than one (1) acre of land, for which a building permit has been issued by the City. All properties which disturb greater than one (1) acre of land shall provide the City with a copy of all National Pollutant Discharge Elimination System permits, a copy of the site Storm Water Pollution Prevention Plan and a site erosion control plan; or
- Agricultural use of land including the implementation of conservation measures included in a farm conservation plan approved by the Soil and Water Conservation District, and including the construction of agricultural structures; or
- Installation, renovation, or replacement of a
septic system to serve an existing dwelling or
structure.
- The Director of Public Works reserves the right to
require any nonagricultural, construction activity,
regardless of land disturbance area or type of activity,
to comply with these requirements if it is determined to
be the cause of or a contributor to an existing or
potential adverse erosion, sediment, or storm water
impact.
- Erosion Control Plan
- An Erosion Control Plan is required for any
activity which disturbs more than one acre in area.
The Erosion Control plan shall be submitted and
approved prior to the issuance of a permit.
- For activities which disturb more than 5000
square feet but less than one acre (43,560 square
feet) the party requesting the permit shall have the
choice of either:
- Submitting a formal Erosion Control Plan or
- Providing perimeter erosion control around
the entire perimeter of the disturbed area,
excepting the entrance, in accordance with the
details herein.
- Submitting a formal Erosion Control Plan or
- For any site one acre or larger in area, the
Erosion Control Plan shall be prepared by a Licensed
Professional Engineer or a Certified Professional in
Erosion and Sediment Control.
- The stabilized construction entrance must be installed prior to any grading or excavation work being performed and in accordance with standard details13.07-K1 and 1307-K2 or bay an equivalent method approved by the Director of Public Works. Developers or builders performing work at construction activities where the sewer and/or water services must be installed under the permanent drive my request permission to install the stabilized construction entrance after the sewer and/or water services are installed. Permission may be granted by the Director of Public Works or their appointee on a case by case basis.
- An Erosion Control Plan is required for any
activity which disturbs more than one acre in area.
The Erosion Control plan shall be submitted and
approved prior to the issuance of a permit.
13.03 DESIGN STANDARDS
- Unless otherwise stated in section 13.04 of this Manual,
all temporary sediment control measures shall be designed to
control sediment from a development for a five (5) year
frequency storm event.
- Design standards for erosion and sediment control
measure shall comply with provisions of this Manual of
Practice and the "Illinois Urban Manual, A Technical Manual
Designed for Urban Ecosystem Protection and Enhancement,"
Prepared by the United States Department of Agriculture -
Natural Resources Conservation Service, as accepted by the
Illinois Environmental Protection Agency, latest edition,
and the Illinois Procedures and Standards for Urban Soil
Erosion and Sedimentation Control (the Green Book, issued by
the Association of Illinois Soil and Water Conservation
Districts) unless otherwise stated by this Manual. In the
event of conflict between provisions of said manuals and of
this ordinance, the following order of precedence procedure
shall apply:
- Town of Normal Ordinances and A Manual of Practice
For The Design of Public Improvements
- Illinois Urban Manual
(Blue Book).
- Illinois Procedures and Standards for Urban Soil Erosion and Sedimentation Control (Green Book)
- Town of Normal Ordinances and A Manual of Practice
For The Design of Public Improvements
13.04 TEMPORARY STORM WATER CONTROL MEASURES
All inlets within the site and any effected inlets off-site shall be protected by one of the methods shown in the Inlet Protection Details included in this chapter (13.07-D, 13.07-E, 13.07-F, or 13.07-G) and in accordance with the approved Erosion Control Plan. On-site sediment control measures shall be constructed and functional prior to initiating clearing, grading, stripping, excavation or fill activities on the site as specified by the following criteria:
- For disturbed areas draining one (1) acre or less,
filter barriers (including filter fences, straw bales,
or equivalent control measures) shall be constructed to
control all runoff leaving the site as specified in this
Manual and in the handbooks referenced in section
13.03-B. Vegetated filter strips, with a minimum width
of 25 feet, may be used as an alternative only with the
permission of the Director of Public Works where runoff
in sheet flow is expected. Perimeter Barrier consisting
of Silt Fence or Straw Bales shall be in accordance with
the Perimeter Barrier Details included in this chapter
(13.07-A1 & 13.07-A2, 13.07-B1 & 13.07-B2, or 13.07-C).
Construction Entrances shall be stabilized in accordance
with the Stabilized Construction Entrance Details
included in this chapter (13.07-K1 & 13.07-K2).
- For disturbed areas draining more than one (1) acre
but less than or equal to five (5) acres, in addition to
the requirements in "A" above, a sediment trap(s) or
equivalent control measure(s), in accordance with the
approved Erosion Control Plan, shall be constructed at
all downslope point(s) of the disturbed area.
- For disturbed areas draining more than 5 acres, in
addition to the requirements of "A" and "B" above,
sediment basin(s) or equivalent control measure(s) shall
be constructed at the downslope point(s) of the
disturbed area.
- Sediment basins and sediment traps designs may
provide for both detention storage and sediment storage.
Sediment basins and sediment traps shall be sized for
the 2-year, 24- hour runoff from the site under maximum
runoff conditions during construction. The release rate
of the sediment basin shall be that rate required to
achieve minimum detention times of at least 8 hours.
- The sediment storage shall be sized to store the
estimated sediment load generated from the site over the
duration of the construction period with a minimum
storage equivalent to the volume of sediment generated
in one year. For construction periods exceeding 1 year,
the 1-year sediment load and a sediment removal schedule
may be substituted.
- Storm water conveyance channels, including ditches,
swales, and diversions, and the outlets of all channels
and pipes shall be designed and constructed to withstand
the expected flow velocity from the 10-year frequency
storm without erosion. All constructed or modified
channels shall be stabilized within 48 hours, consistent
with the following standards:
- For grades up to 4 percent, seeding in
combination with mulch, erosion blanket, or an
equivalent control measure shall be applied. Sod or
erosion blanket or mat shall be applied to the
bottom of the channel (unless a continuous flow of
water is present).
- For grades of 4 to 8 percent, sod or an
equivalent control measure shall be applied in the
channel.
- For grades greater than 8 percent, rock, riprap,
or an equivalent control measure shall be applied,
or the grade shall be effectively reduced using drop
structures. Ditch checks, shall be constructed in
accordance with the Ditch Check Details included in
this chapter (13.07-H, 13.07-I, or 13.07-J) and in
accordance with the approved Erosion Control Plan.
Straw bale ditch checks shall not be allowed.
- For grades up to 4 percent, seeding in
combination with mulch, erosion blanket, or an
equivalent control measure shall be applied. Sod or
erosion blanket or mat shall be applied to the
bottom of the channel (unless a continuous flow of
water is present).
- Disturbed areas shall be stabilized with temporary
or permanent measures within 7 calendar days following
the end of active disturbance, or re-disturbance,
consistent with the following criteria, weather
conditions permitting.
- Appropriate temporary or permanent stabilization
measures shall include seeding, mulching, sodding,
and/or non-vegetative measures.
- Areas having slopes 25 percent or greater shall
be stabilized with sod, mat or blanket in
combination with seeding, or equivalent.
- Appropriate temporary or permanent stabilization
measures shall include seeding, mulching, sodding,
and/or non-vegetative measures.
- Land disturbance activities in stream channels with
permanent or semi-permanent flow shall be avoided, where
possible. If disturbance activities are unavoidable, the
following requirements shall be met:
- Construction vehicles shall be kept out of the
stream channel to the maximum extent practicable.
Where construction crossings are necessary,
temporary crossings shall be constructed of
non-erosive material, such as riprap or gravel.
- The time and area of disturbance of stream
channels shall be kept to a minimum. The stream
channel, including bed and banks, shall be
restabilized within 48 hours after channel
disturbance is completed, interrupted, or stopped.
- Whenever channel relocation is necessary, the
new channel shall, where possible, be constructed in
the dry and fully stabilized before flow is
diverted.
- Construction vehicles shall be kept out of the
stream channel to the maximum extent practicable.
Where construction crossings are necessary,
temporary crossings shall be constructed of
non-erosive material, such as riprap or gravel.
- Storm sewer inlets and culverts shall be protected
by sediment traps or filter barriers in accordance with
the Pipe Outlet Details included in this chapter
(13.07-L or 13.07-M) and the Inlet Protection Details
included in this chapter (13.07-D, 13.07-E, 13.07-F, or
13.07-G) and in accordance with the approved Erosion
Control Plan.
- Soil storage piles containing more than 10 cubic
yards of material shall not be located with a downslope
drainage length of less than 15 feet to a roadway or
drainage channel. Filter barriers, including straw
bales, filter fence, or equivalent, shall be installed
immediately on the downslope side of the piles.
- If dewatering devices are used, discharge locations
shall be protected from erosion. All pumped discharges
shall be routed through appropriately designed sediment
traps or basins, or equivalent.L. Each site shall have
graveled (or equivalent) entrance roads, access drives,
and parking areas of sufficient length and width to
prevent sediment from being tracked onto public or
private roadways. Any sediment reaching a public or
private road shall be removed by shoveling or street
cleaning (not flushing) before the end of each workday.
Any tracked material causing a hazard on a public or
private road shall be removed (as defined above)
immediately.
- All temporary and permanent erosion and sediment
control practices must be maintained and repaired as
needed to assure effective performance of their intended
function until permanent ground surface protection and
permanent storm water control measures are established.
- All temporary erosion and sediment control measures
shall be disposed of within 30 days after final site
stabilization is achieved with permanent soil
stabilization measures. Trapped sediment and other
disturbed soils resulting from the disposition of
temporary measures should be permanently stabilized to
prevent further erosion and sedimentation.
- The Director of Public Works may require additional
control measures as necessary after site inspection if
sedimentation controls are not functioning properly.
- A performance guarantee will be required for erosion, sediment, and storm water control measures.
13.05 TEMPORARY SEEDING
All disturbed areas including lots not anticipating further construction within fourteen (14) days shall have ground surface seeded within seven (7) days, weather and soil conditions permitting in accordance with Illinois Urban Manual Practice Standard 965. Where the initiation of stabilization measures by the 14th day after construction activity temporarily cease is precluded by snow cover, stabilization measures shall be initiated as soon as practicable.
13.06 PERMANENT SEEDING
Within seven (7) days after completion of construction and soil conditions are suitable, and before final inspection, the development must have permanent seeding or other ground cover planted or installed. Where the initiation of stabilization measures by the 7th day after construction activity permanently cease is precluded by snow cover, stabilization measures shall be initiated as soon as practicable. Public improvements will not be accepted until all public right-of-ways and all other areas (not under construction) have permanent seeding established
Final plat public improvement payment, performance and workmanship bonds will not be released except in accordance with Section 24-3.9 of the City Code until all public right-of-ways and all other areas (not under construction) have permanent seeding established.
Permanent seeding shall be in accordance with Illinois Urban Manual Practice Standard 880. Seed mixtures shall be as follows:
Seeding Rate
| Seed Mixture | lbs/ac | lbs/1000sq. ft. | Use |
| Kentucky blue grass | 110-130 | 2.5 - 3.0 | adjacent to residential properties(use at least 3 varieties) |
| Kentucky blue grass | 110 | 2.5 | |
| Red fescue | 44 | 1.0 | ditches and nonresidential areas |
13.07 STANDARD DETAILS
| Standard Drawing No.td> | Title |
| 13.07-A1 & 13.07-A2 | Perimeter Barrier - Silt Fence |
| 13.07-B1 & 13.07-B2 | Perimeter Barrier - Silt Fence with Wire Support |
| 13.07-C | Perimeter Barrier - Straw Bale |
| 13.07-D | Inlet Protection - Block and Gravel |
| 13.07-E | Inlet Protection - Fabric Drop |
| 13.07-F | Inlet Protection - Gravel and Wire Mesh |
| 13.07-G | Inlet Protection - Straw Bale Barrier |
| 13.07-H | Rock Ditch Check - Coarse Aggregate |
| 13.07-I | Rock Ditch Check - Rip rap |
| 13.07-J | Silt Fence Ditch Check |
| 13.07-K1 and 13.07-K2 | Stabilized Construction Entrance |
| 13.07-L | Pipe Outlet to Flat Area |
| 13.07-M | Pipe Outlet to Channel |