(A) General provisions.
(1) There are three ways to accomplish urban soil erosion and sedimentation control:
(a) Allow erosion to take place and then control sediment before it leaves a site;
(b) Stop erosion in the watershed (project area) by soil stabilization or runoff control measures; and
(c) A combination of the two (most desirable).
(2) The following is a list of common measures that can be used to control erosion and sediment. It is by no means an exhaustive list. Some standard drawings are included in this appendix. Additional drawings, standards, and specifications can be found in the Illinois Urban Manual, IEPA and USDA, NRCS, 1995 and the Illinois Standards for Urban Soil Erosion and Sediment Control, the Urban Committee of the Association of the state’s Soil and Water Conservation Districts, revised July 1988.
(B) Control measures.
(1) (a) Perimeter sediment control measures are to be installed between disturbed areas (including stockpiles) and property lines or drainage ways in order to protect off-site areas.
(b) Control measures should be installed on the down-slope sides of the disturbed areas where runoff will leave the site.
(2) Control measures for different slopes.
Slope Range | Control Measure | Comments |
Slope Range | Control Measure | Comments |
Less than 2% | Vegetative (grass) filter strips; no minimum width requirement | |
2% to < 5% | Vegetative (grass) filter strips; ten feet wide, minimum | Size should be increased in proportion to the drainage area and slope |
Filter fence | Drainage area less than one-half acre per 100 feet; see standard for spacing criteria | |
Straw bales | For use in small drainage areas, see standard for spacing criteria, maximum life is three months | |
Vegetative buffer area (other than grass), about 50 feet wide, minimum | Minimizing disturbed areas is desirable; increase buffer size in proportion to drainage area and slope | |
Sediment basin | Can handle sediment from a larger area | |
5% to < 10% | Vegetative (grass) filter strips 20 feet wide, minimum | Size should be increased in proportion to the drainage area and slope |
Filter fence | Drainage area less than one-half acre per 100 feet, see standard for spacing criteria | |
Straw bales | For use in small drainage areas, see standard for spacing criteria, maximum life is three months | |
Vegetative buffer area (other than grass), about 100 feet wide, minimum | Minimizing disturbed areas is desirable; increase buffer size in proportion to drainage area and slope | |
Sediment basin | Can handle sediment from a larger area | |
> 10% | Filter fence | Drainage area less than one-half acre per 100 feet, see standard for spacing criteria |
Sediment basin | Can handle sediment from a larger area | |
(3) (a) Inlet sediment control is to be installed around storm sewer of other inlets to prevent sediment from entering the system. There are many different types depending on the type of inlet.
(b) Common measures include:
1. Inlet protection - excavated drain (division (F) below);
2. Inlet protection - block and gravel (division (G) below); and
3. Inlet protection - staked straw bales (division (H) below).
(4) (a) Mud and dust control is used to prevent mud and dust from leaving the site.
(b) Common measures include:
1. Stabilized construction entrance (division (I) below); and
2. Dust control, see the standards and specifications.
(C) Runoff control.
(1) Concentrated flow areas.
(a) Temporary erosion control measures should be installed to protect drainage ways such as road ditches and waterways until the area is permanently stabilized.
(b) Common measures include:
1. Rock checks for waterways (division (J) below);
2. Fabric checks for waterways (division (K) below); and
3. Erosion blanket.
(2) Outlet protection.
(a) All outlets should be stabilized to prevent downstream areas from erosion.
(b) Common practices include:
1. Pipe outlet channel (division (L) below); and
2. Pipe outlet to flat area.
(3) Diversions. Surface runoff from adjacent areas should be diverted around disturbed areas to stable outlets to reduce erosion due to surface runoff.
(D) Soil stabilization. (Recommended seeding dates for central Illinois are shown in bold.)
(1) Vegetative soil cover.
(a) Temporary seeding is proved a temporary quick cover to control erosion when permanent seeding is not desired or the time of year is inappropriate. (Early Spring - September 30.)
(b) Permanent seeding provides permanent vegetative cover to control erosion, filters sediment from water; may be part of final landscaping plan. (Spring seeding: early Spring - May 15; Fall seeding: August 1 - September 10.)
(c) Dormant seeding is the same as permanent seeding except seeding is done during dormant season. Higher rates of seed application are required. If no mulch is applied, then perimeter controls should be maintained until the vegetation is established. (November 15 - March 1.)
(d) Sodding is quick, permanent cover to control erosion; quick way to establish vegetative filter strip; and can be used on steep slopes or in drainage ways where seeding may be difficult. (Anytime, except when the ground if frozen.)
(e) Ground cover provides ground cover, shrubs, and trees in addition to permanent vegetation; may be used as part of a final landscape plan along with shrubs and trees.
(2) Non-vegetative soil cover.
(a) Mulching provides added insurance of a successful temporary or permanent seeding, controls unwanted vegetation and preserves moisture, and provides cover where vegetation cannot be established.
(b) Aggregate cover provides soil cover on roads and parking lots and areas where vegetation cannot be established; prevents mud from being picked up and transported off-site.
(c) Paving provides permanent cover on parking lots, roads, or other areas where vegetation cannot be established.
(E) Silt fence plan.
(F) Inlet protection, excavated drain plan.
(G) Inlet protection, block and gravel plan.
(H) Straw bale barrier plan.
(I) Stabilized construction entrance plan.
(J) Rock checks for waterways.
(K) Fabric checks for waterways.
(L) Pipe outlet to channel.
(Prior Code, 8 TCC 3-Appendix B)