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Urban Soil Erosion and Sediment Control

Urban Soil Erosion and Sediment Control

United States Department of Association of Illinois Natural Resources and Conservation Service Conservation Districts

Urban Soil and Control

Conservation Practices for Protecting and Enhancing Soil and Water Resources in Growing and Changing Communities

March 2008

Urban and Conservation Practices for Protecting and Enhancing Soil and Water Resources

Introduction What’s inside change is a fact of life for many communities in Illinois. From cities to suburbs to rural villages, farmland Page Topic is being developed to accommodate a population that wants larger homes, larger lots and more shopping, 2 Regulations for Illinois recreation, schools and . 3 What is Soil Erosion and What is Sediment? 4 How to Control Erosion? These land use changes are intensifying pressure on the 5 Strategies and Dust Control 6 Temporary/Permanent and Mulching natural environment. When land is under construction, 7 Rolled Products (RECPs) and soil erosion can be significant – often many times greater Compost Blanket than on land used for agriculture. The resulting sediment 8 PAM* Application for Erosion Control and Outlet damages resources (including community Protection water supplies), obstructs roads and degrades wildlife 9 How to Control Sediment? habitat. 10 Barriers/Filters and Stabilized Construction Entrance Once developed, the land has more roofs, roads, parking 11 Inlet Protection and /Trap lots, and compacted turf. Impervious surfaces like these 12 PAM* Application for Sediment Control and Filter send more runoff across landscapes, and consequently, Strips the risk of flooding is increased. impairs 13 Where to go for help and Additional Information water quality in , and by delivering *PAM = polyacrylamide (water-soluble anionic) sediment, nutrients, hydrocarbons and other pollutants. Ground water recharge is also reduced by impervious surfaces.

This brochure provides information about specific strategies for addressing soil erosion and sediment control on construction sites and on land that is already developed. It will help local decision-makers meet the changing land use needs of communities without compromising the need for clean and abundant water, protection from flooding, recreation amenities, and preserving wildlife habitat.

Developers, planners, engineers, local units of government, and interested citizens will find this brochure helpful for understanding: • Soil erosion and processes and issues, • Illinois water quality laws and regulations related to erosion and sedimentation, Aerial photo with contour lines showing lakes and wetlands • Specific practices that protect local natural that will need protection if adjacent upland areas are resources by controlling soil erosion and disturbed for future development. sedimentation. For each practice, this guide will: • Provide a description, For more information on practice selection, design, • List design techniques for implementation, implementation and maintenance, refer to the most • Indicate challenges or limitations that may limit edition of the Illinois Environmental Protection Agency’s effectiveness, “Illinois Urban Manual: A Technical Manual Designed for • Illustrate with photos. Urban Ecosystem Protection and Enhancement.” (This list of practices is not all inclusive and may not work for every situation. Evaluation of each situation must be made before deciding on a specific practice.)

1 Why be concerned? Urban runoff and construction Nonpoint Pollutants site erosion have been identified as Most common pollutants from Urban Land after Construction is significant sources of pollution for surface completed: water quality. • Nutrients Sediment deposits destroy fish • Hydrocarbons spawning areas, resulting in the loss • Pathogens of sensitive or threatened fish species; • Sediment & Grit adversely impact aquatic insects which • Organic Matter (e.g. lawn clippings, leaves) are at the base of the chain; reduce • Litter capacity; and decrease the • Thermal Pollution (heated runoff from impervious surfaces) overall quality of lakes, streams and wetlands. Sedimentation can cause flooding; piers, pipelines, , discharging or In addition, in designated require additional water treatment; pose other work in navigational of the urbanized areas, there are regulations safety and nuisance issues on roadways; U.S. requiring permit applications for storm and increase cost of construction and water discharges for industrial sources maintenance. Chemicals (such as Clean Water Act of 1977 (CWA) and municipal separate storm sewer some , , as Formerly known as the Federal Water systems (MS4’s). Communities with as toxicants and trace metals) can be Pollution Control Act, this statute was greater than 10,000 population (ILR40 transported with sediment to receiving enacted to address the problem of water permit) are required to implement six waters where they cause additional quality by reducing the of minimum control measures to improve damage to aquatic ecosystems. pollutants into lakes, , streams and the quality of storm water runoff. The And lastly, it is a Federal, state and wetlands. The CWA established a system control measures include the following: sometimes local law to place good soil of water quality standards, discharge • Storm water runoff control from erosion and sediment control practices limitations and permits. construction sites. on construction sites. In Illinois, US-EPA has delegated • Post-construction storm water responsibility for Section 401 and 402 to management for developments. the Illinois EPA. Prior to the issuance of • Detection and elimination of illicit Nonpoint Pollutants either a Section 402 or 404 permit, you discharges to storm sewer systems. Most common pollutants from must obtain a Section 401 certification. • Public education and outreach construction sites: This states that any discharge complies regarding storm water runoff • Sediment with all applicable effluent limitations impacts. • Oil & Greases and water quality standards in Illinois. • Public involvement in storm water • Concrete Truck Washout See the following for each Section runoff related issues. • Construction Debris explanation. • Good housekeeping procedures and • Construction Chemicals practices. Section 401-Water Quality Water Quality Regulations Certification Section 404-Dredge or Fill (What the Law Requires) You must receive the Section Permitting You should be aware that the US Army 401 certification before applying for a Establishes a permit program to Corps of Engineers (Corps) and the US federal permit for any work, which may regulate the discharge of dredged or Environmental Protection Agency (US- result in a discharge to waters of the fill material into waters of the U.S., EPA) are the two federal agencies that U.S., to ensure that actions would not including some wetlands. This section regulate water quality. Both agencies violate Illinois’ water quality standards. of the CWA is administered by the have authority under Section 404 of the Corps. Clean Water Act (CWA), but only the Section 402 – National Pollutant Corps has the authority under Section 10 Discharge Elimination System Ordinances in Illinois of the Rivers and Harbors Act. A review (NPDES) Check to see if your county or by other federal and state agencies, as NPDES requires that a Storm municipality has implemented ordinances well as public notification, is provided Prevention Plan or other enforcement mechanisms prior to the issuance or denial of permit. (SWPPP), including a soil erosion and that require water quality and quantity sediment control plan, be developed issues be addressed during the land Section 10 – Rivers and Harbors Act for all construction activity projects that development process. Ordinances often of 1899 (RHA) require a permit. require the implementation of both Under the RHA, the Corps regulates Current regulations require a temporary and permanent “Practices”. “all work or structures” placed in or permit for ALL construction activities in The development of a soil erosion affecting the navigational waters of the Illinois (ILR10 permit) that disturb one and sediment control plan prior to the U.S. You are required to get a permit (1) acre or more, or smaller projects onset of construction is also often a from the Corps for marinas, bulkheads, that are part of a larger common plan requirement of these ordinances. stabilization, shoreline protection, of development or sale. 2 What is Soil Erosion? Erosion is a three-step process involving the detachment, transport and of soil particles. There are many kinds of erosion. Sheet and erosion, erosion, streambank/bed erosion and erosion are the primary concerns. Each of these types of erosion involves the detachment and transport of soil and downstream/downwind deposition of sediment.

What is Sediment? Sediment is the result of erosion. Once soil particles have detached from the surface, are transported from their site of origin and have come to rest on other ground surfaces or in lakes, ponds, watercourses, or wetlands, they are referred to as sediment. The process of soil particles being transported and deposited is known as sedimentation.

Types of Erosion

Mechanism for Sheet & Rill Erosion: Gully Erosion: Rill Streambank and Wind Erosion: Wind Erosion: When Sheet erosion is the uniform erosion evolves into Streambed Erosion: erosion is similar to impacts exposed soil movement of a thin layer gully erosion as runoff This type of erosion is the sheet erosion in that particles, the particles of soil from sloping, bare, increases, from one scouring away of detachment, transport, dislodge and splash into unprotected land. Falling heavy rain or a series of banks. Degrading or and deposition of soil the air. The dislodged raindrops detach soil particles storms over time. A gully streambeds particles occur, except that particles can become which go into as is generally defined as a and/or repeated high wind is the transportation suspended in the runoff occurs. Detached scoured out area that is flows for extended mechanism rather than water and can easily particles are transported not crossable with duration causes bank water. be transported great down slope/ to a point or grading equipment. erosion. Streambank and distances by surface of deposition. form with streambed erosion is a water runoff. longer, harder when significant contributor of runoff volumes accelerate. sediment loads to surface Erosion increases as slope/ water resources. grade becomes steeper and with longer slope length.

What are the Issues? All sites being developed will vary in their suitability for different types of development. Knowing the , topography, features, area, on and off-site , flooding potential, and other pertinent data help identify both beneficial features and potential problems of a site and adjacent areas. Generally, the location of the site has already been determined. What is needed then are the best procedures for identifying and addressing potential or existing problems, or for addressing established restrictions, ordinances, or regulations to develop a site in a quality manner.

Proper site planning can identify areas particularly susceptible to erosion. These areas should be avoided if possible. If not, planning and timely implementation of practices will be needed to minimize negative on and off- site impacts. Graphic shows site analysis including land features such as rivers, lakes, wetlands, life, , structures, etc. Planning Process The process outlined in the Illinois Urban Manual is a standard process used by the Natural Resources Conservation Service (NRCS) and others. It is a nine-step process that is fully explained in NRCS’s National Planning Procedures Handbook. The nine steps are:

1. Identify problems 4. Analyze resource data 7. Make decisions 2. Determine objectives 5. Formulate alternatives 8. Implement plan 3. Inventory resources 6. Evaluate alternatives 9. Evaluate plan

3 How to Control Erosion? Understanding how erosion occurs is essential to the design and implementation of effective erosion control plans. Two main keys to erosion control are preventing the detachment of soil particles and reducing the volume of runoff. Erosion control may also be achieved by establishing protective cover such as temporary or permanent seeding, mulching, applying a compost blanket, or installing rolled erosion control products (mats or blankets).

Erosion control should be emphasized as the primary design goal before sediment control in a soil erosion and sediment control plan. Once erosion control is implemented, sediment control should be utilized. Controlling erosion is easier and less expensive than sediment control. By preventing soil particles from being detached, less sediment will need to be controlled.

Grading strategies, such as minimizing the area exposed at any given time, is the most effective way of reducing the potential for erosion to occur.

Erosion Control Practices Erosion control practices discussed and examined in this section:

• Grading Strategies 1 • Dust Control2 • Temporary/Permanent Vegetation 3 • Mulching4 • Rolled Erosion Control Products (R.E.C.P.)5 • Compost Blanket 6 • PAM (polyacrylamide) Application for Erosion Control 7 • Outlet Protection 8 2 1

3

4 5

7 8

6

4 Grading Strategies . . . designing developments to fit the existing landscape minimizes the amount of required grading. Minimizing grading reduces the amount of land exposed to erosion and saves money. Coordinate essential grading to minimize the potential for erosion.

Design Techniques Challenges/Limitations • Phased grading maintains • Each grading phase needs to be strategic vegetative cover planned carefully to assure time and cost and minimizes the amount efficiencies are realized. of disturbed land at any • Marginal or steep sites may require given time to reduce extensive grading to allow for building erosion. sites and road construction. • Phasing divides essential • Mass grading is a standard practice in grading into distinct portions. some areas due to costs and contractor Grading of each phase is specialization. started, completed and stabilized in sequence. • Generally, it is best to start . This increases grading activities at the top of , decreases runoff, and a site first and then move down improves rooting depth. the gradient. Maintain vegetative • Use temporary or permanent cover (buffer strips) as the site stabilization techniques as soon work progresses. as site grading is completed. • Deep tillage should be done as • Protect areas of existing the final step of grading activity and other natural vegetation that at each phase to reduce soil will be preserved.

Dust Control. . . a temporary control of dust blowing and movement from exposed soil surfaces on construction sites and roads. Typical methods of dust control include , vegetative barriers, binding agents and irrigation.

• Irrigation is commonly used and affords fast protection for haul roads and other heavy traffic roads. The site is sprinkled with water until the surface is moist. Repeat as needed. • Barriers such as solid board fences, fences, burlap fences, crate walls, Design Techniques bales of hay and similar material can be • - Chemical or wood cellulose used to control air currents and blowing fiber binders should be used instead soil. of emulsified asphalt to bind mulch • Calcium chloride can be applied at a material due to environmental rate that will keep the surface moist. considerations. Application rates should be strictly in • Existing trees or large shrubs may Challenges/Limitations accordance with the manufacturer’s afford valuable protection if left in place. • When temporary dust control measures specified rates. • Spray-on binding agents, such as PAM are used, repetitive treatment may need • Crushed stone or coarse may be (polyacrylamide), may be used on to be applied as needed to accomplish used to control dust on roads or other . They should not be used control. areas during construction. on organic soils. Keep traffic off these • Paved areas that have soil on them areas after application. from construction sites should be • Roughen the surface and bring clods cleaned daily, or as needed, utilizing to the surface. This is an emergency a street sweeper or bucket-type end- measure that should be used before loader or scraper. soil blowing starts. 5 Temporary and Permanent Vegetation . . . temporary seeding helps reduce runoff and erosion during construction. Permanent seeding stabilizes disturbed or exposed areas in a manner that adapts to site conditions and allows selection of the most appropriate plant materials for long-term erosion control.

• Reseed areas as soon as possible where seedling emergence is poor or where erosion occurs.

Challenges/Limitations • Temporary seeding provides protection for no more than one year, during which Permanent Seeding time permanent stabilization should be initiated. • All permanent seeding should be Temporary Seeding mulched upon completion of seed application or planting. Design Techniques (Permanent) • Native species are recommended Design Techniques (Temporary) • Prior to seeding or planting, the due to their deep structure and • Temporary seeding applies to all seedbed should be relatively free cleared, unvegetated, or sparsely of all weeds, stones, , sticks, increased infiltration and filtering vegetated soil surfaces where rivulets, , crusting and caking, abilities. vegetative cover is needed for less than or debris which may interfere with • Follow seeding rate recommendations. one year. seeding or planting operations or plant • Prior to seeding, install other necessary establishment. Challenges/Limitations erosion control and sediment control • All legumes should be inoculated with • The site should not be worked when practices if possible to avoid disturbing the proper inoculant prior to seeding. frozen or saturated. the area being planted. • Seeding may be done by any of the • The grading plan should utilize • Seed should be evenly applied with a following methods: techniques and equipment that cyclone seeder, drill, cultipacker seeder • Conventional Drill minimize . or hydroseeder. • Broadcast Seeding • Some cannot be grown readily • Seeding made during optimum • Hydroseeding from seed and should be planted using and late summer seeding dates, with • Dormant Seeding , transplant, or other planting favorable soil and site conditions, will • No- methods. not require mulch.

Mulching . . . is applying vegetative residue, tackifier or other material to ensure the residue remains in place to protect the soil surface from the impact of raindrops or the erosive of wind until vegetative cover is established. Mulching conserves moisture for seedlings and protects them from temperature extremes. Mulching limits soil erosion and lessens the need to contain sediment. Mulches most often used include straw, fiber or wood chips.

Design Techniques Challenges/Limitations • Mulching is one of the best ways to • Mulches are limited by severe slopes. provide instant erosion control on a On steeper slopes, rolled erosion bare site to protect it until vegetation control products should be used. can be established. • Mulch is not effective at stabilizing • Straw mulches do not bond to the soil. channels or other areas of They must be crimped in by disking to concentrated flows. A rolled erosion prevent them from blowing away. They control product is recommended for can also be held in place by spraying areas of concentrated flow. on a tackifier (glue) or fiber mulch to • Too much mulch or uneven distribution hold the straw in place. of mulch can smother new grass • Straw mulch is usually applied at a rate seedlings. of 1-2 tons per acre. • Fiber mulches are chopped up paper or wood fiber and are typically sprayed on as a slurry along with seed.

6 Rolled Erosion Control Products (RECPs) . . . apply Turf Reinforcement Mats (TRM) or Erosion Control Blankets (ECB) of organic or synthetic materials to the soil surface to protect disturbed areas from erosion until vegetative cover is established. Rolled erosion control products are especially effective at controlling erosion on severe slopes or areas of concentrated flows.

Design Techniques Challenges/Limitations continued • Choose TRMs or ECBs depending on • ECBs are temporary products with application and site conditions. Proper typical life spans ranging from 3 to 36 selection and installation of RECPs months. They are used in situations is critical to successful use of these where natural vegetation alone will provide sufficient permanent erosion products. control protection. • Trenching, overlapping, and stapling • TRMs are permanent products that must be completed according to provide reinforcement manufacturer’s recommendations. to natural vegetation • Seedbed preparation and seeding are during and after done prior to blanket installation (some maturation. They blankets have seed embedded). are typically used • RECPs are highly recommended with in high flow ditches other velocity minimization practices for and channels, steep protecting areas of concentrated flows. slopes, streambanks, and shorelines Challenges/Limitations where erosive forces • Labor intensive. exceed what natural • Cannot use on frozen ground, vegetation can sustain roughened ground, or established or in areas where only vegetation. limited vegetation • More expensive than mulching. establishment can be • Careful consideration to grading and expected. shaping is required. Shown here are different types of RECPs and coir fiber roll being used to stabilize the shoreline.

Compost Blanket . . . provides a soil amendment consisting of decomposed organic waste with a consistency similar to high quality but with a much higher organic matter content. The high organic matter content of compost absorbs the impact of raindrops, which prevents detachment of soil particles. Organic matter also retains water on site to reduce runoff and potential transportation of sediment or other pollutants.

Design Techniques Challenges/Limitations • Compost can be applied to a depth • Compost blankets should specified for site conditions using not be used in areas of manure spreaders, bulldozers, end concentrated water flow or loaders, or pneumatic blower trucks. slopes steeper than 3(H) to Generally, a two-inch minimum blanket 1(V). depth is recommended. • Access to composting • Compost blankets are effective as facilities and adequate temporary site stabilization while supplies of compost may vegetation is established. limit use of compost • Seeding is completed after the compost blankets in some locations. blanket has been installed or as the blanket is being installed with a blower truck. • Compost amended soils contribute to rapid establishment of vegetative cover and water retention. • Before applying the compost blanket, construction surface should first be scarified or tilled. 7 PAM Application for Erosion Control . . . a land application of products containing water-soluble anionic polyacrylamide (PAM) as temporary soil binding agents to reduce erosion. The purpose of this practice is to reduce erosion from wind and water on construction sites and agricultural lands.

should follow manufacturer’s • PAM for erosion control is a temporary recommendations but should not practice, with effectiveness limited to a exceed limits established in Material maximum of four months. Data Safety (MDS) sheets. • PAM use should be limited to finely • PAM may be applied either in solution textured , clays and colloidal or in granular form. The method particles. chosen should ensure a uniform • PAM must be reapplied to areas coverage of active polymer over the disturbed after initial application. area to be stabilized. • Overuse of PAM application can lead • Additional practices such as to clogging of soil pores, resulting in seeding and mulching enhance PAM reduced infiltration and increase runoff effectiveness and duration. and erosion. Design Techniques • Consider the cost of PAM compared • PAM is intended for direct soil surface to other forms of treatment such as application to sites where the timely mulching or RECPs. Depending on the establishment of vegetation may not application where it is used, PAM may be feasible. Such areas may include Challenges/Limitations be a more cost effective alternative. construction sites where land disturbing • PAM for erosion control should only • Inhaling granular polymer may cause activities or winter shutdown prevent be used in areas of sheet flow. PAM choking or difficulty breathing. Persons establishment or maintenance of a is not designed for use in areas of handling and mixing polymer should temporary or permanent seeding. concentrated flows. use personal protective equipment • Only the anionic form of PAM should be • PAM should not be applied on frozen of a type recommended by the used. Cationic PAM is toxic. soils or when is present at the manufacturer. • Soils on-site should be tested for the surface. • Polymer mixtures combined with water appropriate PAM to ensure successful • Additional practices will be required are very slippery and can pose a safety applications and results. when PAM is applied to slopes steeper hazard. • Application rates and methods than 3(H) to 1(V).

Outlet Protection . . . a section of protection placed at the outlet end of culverts, conduits or channels. Rock outlet protection prevents scour erosion, protects the outlet structure and minimizes the potential for downstream erosion by reducing the velocity and energy of concentrated flows.

Design Techniques Challenges/Limitations • A -lined apron is the • Inspect riprap outlet structures after most commonly used practice heavy rains to see if any erosion for this purpose because of its around or below the riprap has taken relatively low cost and ease of place or if stones have been dislodged installation. and take steps to repair. • Apron length and width • Stilling basins or plunge pools may be should be determined based required where overfalls exist or where on appropriate tail water excessive apron length is required. condition, discharge velocity • Discharge velocities greater than 10 and shape of outlet area. feet per second will require special • Stone for riprap should consist design for energy dissipation. of field stone or rough quarry • This practice applies to the immediate stone. • In all cases, filter fabric shall be placed area or reach below the pipe or channel • Recycled concrete equivalent may between the riprap and the underlying and does not apply to continuous rock be used provided it has a density of soil to protect soil movement into and linings of channels or streams. at least 150 pounds per cubic foot, through the riprap. • Pipe outlets at the top of cuts or on does not have any exposed steel or • The riprap should be extended slopes steeper than 10 percent cannot reinforcing bars, and provided the downstream until stable conditions are be protected by rock aprons or riprap longest dimension (length, width, reached even though this may exceed sections due to reconcentration of flows thickness) of each piece is not more the length calculated for velocity and high velocities encountered after than 3 times its smallest dimension. control. the flow leaves the apron.

8 What is Sediment Control? Sediment control, which is often confused with erosion control, is trapping detached soil particles that are already moving in the erosion process. Slowing the velocity of runoff and providing vegetative filtering helps trap sediment on-site, but typically, sediment control is achieved by temporarily impounding flows to allow sediment to settle out. It is critical that effective sediment control practices be installed and maintained when soil is exposed to the erosive of rain and wind. Sediment control should be a secondary design goal in a soil erosion and sediment control plan, after erosion control is addressed to the extent practical.

Sediment Control Practices Sediment control practices discussed and examined in this section:

• Barriers/Filters1

• Stabilized Construction Entrance2

• Inlet Protection Devices3

• Sediment Basins/Trap4

• PAM Application for Sediment Control5

• Filter Strips6 1

2

4 3

6 5

9 Silt Fence Barriers/Filters . . . temporary barrier of fabric anchored in the ground and supported by posts on the downstream side of the fabric. Some fabrics are designed to allow water to pass through and filter out the sediment. Other materials act as a barrier, not allowing water to flow, but redirecting water runoff to a suitable outlet. Design Techniques Challenges/Limitations • Silt fences can be sliced or trenched • Silt fences should not be placed in into the ground. Slicing normally areas of concentrated flows. creates a more secure system as the • Sediment deposits should be removed ground can be compacted more fully after each rainfall, and must be to prevent undercutting of the fence. removed after reaching one-half the • Install silt fences on the contour with height of the silt fence. the ends extending upslope. • Compacted material may • Maximum allowable slope length prevent wooden supporting posts contributing to a silt fence is being driven in to the depth required dependent on slope steepness. The to adequately support the geotextile steeper the slope, the shorter the fabric. The use of metal posts may allowable contributing slope length alleviate this problem. (shorter the distance). • Other practices may also need to be • The maximum drainage area for allow opening sizes to be specified, considered. overland sheet flow to a silt fence allowing targeted particle sizes to be • Silt fences are a high maintenance should not exceed 1/2 acre per 100 feet trapped. practices. of fence. • When silt fence is used for perimeter • The use of wire backing may interfere • Wire backing may be used to increase sediment control, it should be installed with easy removal and disposal once post spacing and strength of the fence. and functioning prior to upslope land the contributing drainage area has been • Choose geotextile fabric based on disturbance. stabilized. maximum post spacing, grab strength, • Ensure a water tight seal is formed permitivity, apparent opening size and when joining two sections of silt fence. ultraviolet stability. Some fabrics will

Stabilized Construction Entrance . . . stabilized pad of aggregate underlain with filter fabric, located at any point where vehicular traffic will be entering or leaving a construction site to or from a public right-of-way, street, alley, sidewalk, or parking area. Stabilized construction entrances prevent the tracking of sediment off-site. Design Techniques must wash the tires before entering a • A stabilized construction entrance public road. A wash rack may be used should be used at all points of to make washing more convenient and construction ingress and egress. effective. • The graveled access should be • The washing station should be located installed before or as soon as practical to provide for maximum utility by all after the start of site disturbance. construction vehicles. • The entrance should remain in place • All sediment from tire wash and pad and be maintained until the disturbed should be prevented from entering area is stabilized by permanent storm drains, ditches, watercourses, or practices. surface waters, including wetlands. • Filter fabric should be used under the aggregate to minimize the migration of Challenges/Limitations stone into the underlying soil by heavy • Maintenance may require periodic top vehicle loads. dressing with additional aggregate to • All surface water flowing or diverted prevent tracking sediment off-site. toward construction entrances should • All sediment spilled, dropped, or washed be piped across the entrance. If piping onto public right-of-way must be removed is impractical, a mountable with immediately. 5(H) to 1(V) side slopes should be used • Periodic inspection and needed to prevent sediment laden water from maintenance should be provided after leaving the construction site. each rain. • If conditions on the site are such that the majority of the is not removed, the vehicles traveling over the gravel 10 Inlet Protection . . . traps and filters sediment before runoff enters storm sewer inlets or culverts. Inlet protection serves as a last line of defense for keeping sediment on-site. Construction sites will always generate some sediment-laden runoff, making inlet protection an important practice. A variety of products and techniques are available to provide inlet protection. Challenges/Limitations • Since inlet protection devices impede direct flow into the , streets may become temporarily flooded or covered with deposited sediment. This may pose a safety issue. • Designers should provide a plan for dealing with impounded water. Deposited sediment should be cleaned promptly. Sediment can also clog the filtering medium, requiring regular Design Techniques maintenance to prevent extended • Inlet protection devices can include constructed in such a manner that ponding of runoff water. surrounding or covering inlets with silt any resultant ponding of storm water • Inlet protection devices must be fences, compost socks or rock filter will not cause inconvenience, safety designed to withstand the expected around the inlet. issue, or damage to adjacent areas or velocity of water under the expected • Traditional control detention structures. sediment load. basins can be retrofitted with an inlet • The maximum area draining to a stone • Inlet protection devices should not be culvert inlet protection should be no protection system to provide water subjected to large sediment loads. Inlet more than 3 acres. quality benefits while maintaining flood protection should provide a final filtering • For drainage areas larger than 3 acres, of runoff, after other components of a control functions. install a sediment basin/trap. • All culvert inlet protection should be storm water pollution prevention plan have done their job.

Sediment Basin or Trap . . . an impoundment for storm water to retain sediment by slowly releasing runoff. Sediment settles out of standing water, so maximizing the time water is impounded increases the amount of sediment retained on site. Basin outlets can be wrapped in geotextile or bedded in gravel to enhance trap efficiency. Design Techniques • Sediment traps are used where • Basins and traps should drainage areas are between 1-5 be designed to include acres in size and have a stone sediment storage, as well outlet structure. Sediment basins as wet (permanent) and dry are used where drainage areas are (temporary) storage. greater than 5 acres in size and utilize • Bed outlets in gravel or an engineered pipe outlet principal wrap them with geotextile spillway with an auxiliary spillway. to help trap fine particles. • Traps can be placed strategically Coagulating agents throughout the construction site and (polymers) are also be temporary in . For instance, available, which cause fine a trap can be installed as part of a particles to clump together phased grading plan and removed as and fall out of . the phase is completed. • Often, a large basin is installed as a Challenges/Limitations perimeter protection practice. Large • Trapped sediment should be cleaned out volumes of water can be captured and • In many cases, sediment basins can regularly to maintain storage capacity retained with this approach. be multi-functional. They can serve as and maximize time of impoundment. • Perimeter basins can be removed and sediment basins during construction • Sediment basins and traps are not the site landscaped after grading is and as wet detention ponds that help efficient for trapping very fine silt and completed and the site is stabilized. manage storm water after development soil particles that stay in suspension is completed. for extended periods. 11 PAM Application for Sediment Control . . . use of products containing water-soluble anionic polyacrylamide (PAM) as temporary soil binding agents to reduce off-site sedimentation into water bodies. The purpose of this practice is to remove sediment from turbid discharged water. Design Techniques • Polymer mixtures should be applied • Only anionic polymers should be used. in conjunction with other erosion Cationic forms are toxic. control practices and under an erosion • The selection of polymer type is site and sediment control or storm water specific. Soil samples should be used management plan. to determine the right polymer to use. • Use PAM treated jute yarn or a floc pit • The key factor to the performance of to trap the floc from sediment-laden polymer is to make sure it is thoroughly water. dissolved and mixed with the turbid • PAM application frequency is water before the floc is able to form. dependent on the volume of water • Application rates and methods being treated. Follow manufacturer’s of application should follow recommendations to determine when manufacturer’s recommendations but floc logs or granules need to be should not exceed Material Data Safety replaced. (MDS) sheets. • All the floc formed from the mixture process must be trapped before water is discharged from the site. Challenges/Limitations • Placement of semi-hydrated block • Inhaling granular polymer may cause should be as close to the source of choking or difficulty breathing. Persons particles as possible. handling and mixing polymer should • When using products in impoundments • Select the form of polymer to be used use personal protective equipment immediately adjacent to, or within (, granulated, or gel block) of a type recommended by the waters of the state, consider using based on location where turbid water manufacturer. products for which the manufacturer’s will be treated. (Examples include • Polymer mixtures combined with water recommended application rate is pipe inlet or discharges, channelized are very slippery and can pose a safety considerably lower than the use or concentrated flows, and bypass hazard. channels.) restriction.

Filter Strips. . . permanent herbaceous vegetation situated between developed land and environmentally sensitive areas to trap sediment, particulate organic matter and/or dissolved contaminants.

Design Techniques • Filter strips should be located along the spreaders, or other measures are down-slope edge of a disturbed area on often required to ensure maximum the approximate contour. effectiveness of the filter strip. • Filter strips should be permanently designated plantings to treat runoff. • Permanent herbaceous vegetation should consist of grasses or a mixture Challenges/Limitations of grasses, legumes and/or other forbs • Filter strips cannot be installed on adapted to the soil and . unstable, eroding channel banks due to • Native species are preferred due to undercutting of the bank toe. their deep root structure and increased • Inspect and repair filter strips after storm infiltration and filtering abilities. events to fill in gullies, remove flow sized according to the area draining to • Filter strips should be maintained to disturbing sediment accumulation, re- the filter strip. function properly. seed disturbed areas, and take other • Filter strips should be used where • Filter strips should be strategically measures to prevent concentrated flow. surface water runoff occurs as overland • The maximum area draining to a filter located to intercept contaminants and sheet flow. strip is 5 acres, the maximum slope of reduce runoff by increasing infiltration • Land grading, the creation of level and ground water recharge, thereby a filter strip is 15 percent. Filter strips protecting water quality. perform best on slopes of 5 percent or • The length and width of the filter strip is less. 12 Where to go for help Soil and Water Conservation Districts http://www.ilconservation.com/soilandwater/htdocs/MEMBERS/ILSWCDs.html

USDA-Illinois Natural Resources Conservation Service (USDA-NRCS) http://www.il.nrcs.usda.gov/technical/ http://www.il.nrcs.usda.gov/contact/directory/ilcntys.html

Illinois Environmental Protection Agency - Bureau of Water http://www.epa.state.il.us/water/

Credits Photography by Illinois Soil and Water Conservation Districts and USDA-NRCS.

Special thanks to Iowa USDA-NRCS for their contributions from the Conservation Strategies for Growing Communities publication.

Additional information Procedures and Standards for Urban Soil Erosion and Sedimentation Control in Illinois; 1988 (Green Book)

Illinois Field Manual for Implementation and Inspection of Erosion and Sediment Control Plans; 1990 (Brown Book)

US Environmental Protection Agency - Menu of Practices http://cfpub.epa.gov/npdes/storm water/menuofbmps/index.cfm?action=min_measure&min_measure_id=4 http://cfpub.epa.gov/npdes/storm water/menuofbmps/index.cfm?action=min_measure&min_measure_id=5

Illinois Urban Manual http://www.il.nrcs.usda.gov/technical/engineer/urban/index.html

USDA-Natural Resources Conservation Service (NRCS): Electronic Field Office Technical Guide (eFOTG) http://www.nrcs.usda.gov/technical/efotg/

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