Presentation on theme: "Sediment & Erosion Control"— Presentation transcript:
1Sediment & Erosion Control KEEPING THE SOIL ON THE SITEMiami County Engineer’s Office – Aug 2004
2Sediment & Erosion Control KEEPING THE SOIL ON THE SITEWhat is Sediment & Erosion Control?The use of various methods to reduce or eliminate the amount of erosion, and resulting sediment loss, that can occur on a construction site when bare soil is exposed to rain and/or snowmelt.
3Sediment & Erosion Control KEEPING THE SOIL ON THE SITEWhy is Sediment & Erosion Control Necessary?There is a legal requirement to practice sediment & erosion control on most construction sites.Proper erosion controls will prevent expensive, time-consuming rework of finish-grade landscape areas after heavy rains.Keeping soil on the construction site will prevent polluted runoff from entering local streams, lakes, and rivers.The Miami County Commissioners and other local political subdivisions are committed to the use of effective sediment & erosion control methods on construction projects undertaken by county, township, and municipal agencies.
4Sediment & Erosion Control KEEPING THE SOIL ON THE SITEIt’s the LawPhase II of the EPA Clean Water Act requires that soil and sediment from construction sites be contained on-site, rather than being carried off the site by rainwater or snowmelt into lakes, rivers, streams, etc.Non point-source pollution, such as sediment from construction sites, is currently the most significant threat to clean water in the United States.
5Sediment & Erosion Control KEEPING THE SOIL ON THE SITEPay Now, or Pay LaterSediment and erosion control practices, such as seeding and mulching, stabilize the soil and prevent costly and time-consuming site rework. It makes sense to do it right the first time to keep from having to come back to do the job over again.
6Sediment & Erosion Control KEEPING THE SOIL ON THE SITEClean Water is Everyone’s BusinessStorm water runoff and the pollution it carries can threaten drinking water supplies, harm fish and wildlife, and ruin recreational opportunities in lakes and rivers. These negative effects harm the economy, degrade our natural resources, and pose a potential health risk.Doing our part to conserve and preserve clean water resources is a responsibility each of us shares.
7Sediment & Erosion Control KEEPING THE SOIL ON THE SITELocal InitiativesMiami County CommissionersBethel, Concord, Monroe, & Union TownshipsMiami Conservancy DistrictMiami Soil & Water Conservation DistrictMiami County Health DepartmentMiami County Planning & ZoningMiami County Engineer’s OfficeLocal Watershed GroupsOSU ExtensionOhio Environmental Protection AgencyYou!
8Know Your Dirt!On average, how many years does it take to form one inch of topsoil?Around 500 years
9Know Your Dirt!The scientific study of soil is called what?Pedology
10Sediment & Erosion Control KEEPING THE SOIL ON THE SITESediment & Erosion Control MethodsConstruction Project PhasingMulching & SeedingSoil Bank StabilizationSilt Fence InstallationInlet ProtectionDitch ChecksConcrete Washout ProceduresConstruction Entrance/Exit Road CompositionSediment Basins
11X X = Sediment & Erosion Control EROSION SEDIMENT KEEPING THE SOIL ON THE SITESediment & Erosion ControlFirst things FirstSediment results from Erosion. Therefore, if you effectively apply erosion controls as a first priority on any project, you will eliminate the need to deal with sediment control.XXEROSIONSEDIMENT=
12Sediment & Erosion Control KEEPING THE SOIL ON THE SITEConstruction Project PhasingCompletion of a construction project in planned phases to minimize the amount of disturbed soil subject to erosion and sediment runoff.EXAMPLE: In a ditch setback improvement involving 6,000 feet of ditch line, typically the entire length of ditch line is roughed up at project onset. This has normally been considered the most efficient use of manpower and machinery.After ditch improvements are made over the course of several weeks, seed/mulch is applied to the entire area at project completion. This subjects the entire 6,000 feet of disturbed soil to the effects of erosion and/or sediment runoff for the life of the project, however long that may be.
13Sediment & Erosion Control KEEPING THE SOIL ON THE SITEConstruction Project Phasing (continued)ALTERNATIVE: Phase the work so only the first 2000 feet of ditch line is disturbed (use some natural terminus like a culvert, field drive, etc.). Make improvements and complete that section of ditch line, up to and including the application of seed & mulch. Then move to the next “phase” of the project, and so on, until the entire project is complete. This approach keeps the soil vegetated or covered as long as possible, prolonging protection from erosion and sediment runoff.
14Sediment & Erosion Control KEEPING THE SOIL ON THE SITEMulching & SeedingEPA regulations require that permanent ground cover in the form of seed and/or mulch be applied no later than seven days after reaching final grade on a project site.If no construction activity is planned at a site for 21 days or longer, temporary ground cover must be applied no later than seven days after soil is first disturbed.In either of the above cases, if the disturbed area is within 50 feet of a stream, the time frame for the application of ground cover is reduced to two days.
15Sediment & Erosion Control KEEPING THE SOIL ON THE SITEMulching & Seeding (continued)Method: Straw Mulch over Grass SeedADVANTAGESDISADVANTAGESLow material expenseLow manpower costsMaterial readily availableEasy to applyStraw works well as seed bedding if kept moistDoes not hold to sloped soils unless an emulsion tackifier is added.Must be kept moist for seed germinationCan be blown off-site by passing cars, wind, or large storm event.Straw waste can contribute to site drainage problems.Approximate Cost: $150 per 5000 sq ft coverage
16Sediment & Erosion Control KEEPING THE SOIL ON THE SITEMulching & Seeding (continued)Method: HydroseedingADVANTAGESDISADVANTAGESSeed, mulch, fertilizer & water applied simultaneouslyLow manpower costs, rapid applicationHolds well to sloped soilsLess affected by wind forcesMulch works well as seed bedding & holds moisture longer than strawCan be affected by large storm eventsMust be kept moist for seed germinationRequires water source in order to be appliedSuccess of germination is affected greatly by the manner in which the hydroseed is appliedApproximate Cost: $300 per 5000 sq ft coverage
17Sediment & Erosion Control KEEPING THE SOIL ON THE SITEMulching & Seeding (continued)Method: Straw/Seed BlanketsADVANTAGESDISADVANTAGESSeed, mulch & fertilizer applied simultaneouslyHolds well to sloped soilsLeast affected by wind forces & rain eventsBlanket works well as seed beddingLabor intensive installationMust spike down blanket with non-biodegradable materialsMore costly than other mulch/seed applicationsMore subject to on-going service & maintenanceApproximate Cost: $400 per 5000 sq ft coverage
18Sediment & Erosion Control KEEPING THE SOIL ON THE SITEMulching & Seeding (continued)Method: SodADVANTAGESDISADVANTAGESImmediate erosion/sediment controlHolds well to sloped soilsUnaffected by wind forces & rain eventsEliminates need for installation of intermediary sediment and erosion control BMPsLow maintenance and/or reworkThe most labor intensive installationMust be kept moist to allow sod to bond to soil substrateWill be cost prohibitive for most projectsMaterials may not be readily availableApproximate Cost: $675 per 5000 sq ft coverage
19Know Your Dirt!Soil scientists have identified more than how many thousands of soil types in the United States?More than 70,000
20Know Your Dirt!An annelid is an animal that lives in the soil. What is its common name?An earthworm
21Sediment & Erosion Control KEEPING THE SOIL ON THE SITESoil Bank StabilizationTo prevent erosive forces from undercutting stream banks or other steep contours, rocks or gabions may be used to stabilize the bank. This application has the side benefit of preventing rain droplet impact with underlying soils, which keeps sediment from leaving the site.
22Sediment & Erosion Control KEEPING THE SOIL ON THE SITESilt Fence InstallationSilt fence is a geotextile screen used to pond storm water and allow sediment to settle out before the water migrates to catch basins, ditches, streams, or lakes. The screen is placed on the downslope side of a construction site, along the contour of the project topography, with enough room behind the silt fence to allow ponding to occur. At each end of the silt fence, the fabric must be directed up-slope so water does not flow around the ends of the material.
23Sediment & Erosion Control KEEPING THE SOIL ON THE SITESilt Fence Installation (continued)SLOPESLOPE LENGTH< 50:1250 FT50:1 – 10:1125 FT10:1 – 5:1100 FT5:1 – 3:175 FT3:1 – 2:150 FT> 2:125 FTSLOPE LENGTH710710708706Drainage Area704Prevent flow around ends by bringing up slopeSet away from steep slope or toe of fill702700
24Sediment & Erosion Control KEEPING THE SOIL ON THE SITESilt Fence Installation - SummarySilt fence needs to be:Installed on the contourTrenched to a depth of 6”Stretched until tightAll joining sections rolledStakes on downslope side, from 4’ to 6’ apartTop of fence 16” above groundEnds of fence elevated
25Sediment & Erosion Control KEEPING THE SOIL ON THE SITESilt Fence - MaintenanceRegular maintenance is needed to assure the silt fence continues to function properly:Inspect installation weekly and after each heavy rainRe-anchor where neededRemove accumulated sediment as necessary, to restore capacityRepair any tears in the geotextile material
26Sediment & Erosion Control KEEPING THE SOIL ON THE SITESilt Fence – Improper UsesSilt fence should never be placed in flowing channels, streams or waterways. The fabric cannot withstand the velocity and volume of water in concentrated flows and will fail quickly.
27Sediment & Erosion Control KEEPING THE SOIL ON THE SITESilt Fence – Rule of ThumbIf it doesn’t pond water, it doesn’t work.
28Know Your Dirt!These are primarily responsible for keeping soil in its place?Roots
29Know Your Dirt!A handful of soil contains more of these than the number of people alive on Earth?Bacteria
30Sediment & Erosion Control KEEPING THE SOIL ON THE SITEInlet ProtectionStorm drain inlet protection is designed to increase the time it takes for sediment-laden water to enter the storm sewer system, through the use of short-term ponding. Ponding allows the sediment to settle out before storm water enters the drain.
31Sediment & Erosion Control KEEPING THE SOIL ON THE SITEInlet Protection - TypesVarious methods can be used to control excess sediment from entering curb drains and surface flow inlets. While ponding is the overall objective, it is not the intent of inlet protection to totally restrict water from flowing into the drain. A measured flow can be achieved through the use of geotextile silt fence material, manufactured inlet control units, or utilization of construction materials available onsite.
32Sediment & Erosion Control KEEPING THE SOIL ON THE SITEInlet Protection - GeotextileThese units use silt fence fabric and wire mesh, wrapped around a metal or wooden frame, as a means to pond water around inlets.
33Sediment & Erosion Control KEEPING THE SOIL ON THE SITEInlet Protection – Manufactured UnitsSome of these units use the weight of the metal inlet grate to hold them in place. Others merely “snake” around the inlet to form a makeshift dam. Usually they are constructed of florescent material in order to be seen clearly on the construction site. As with all Inlet Protection BMPs, their success depends upon maintenance and upkeep throughout the construction project and into the post-construction phase, until vegetation is established on the site.
34Sediment & Erosion Control KEEPING THE SOIL ON THE SITEInlet Protection Using Construction MaterialsGravel, concrete block, and wire screen can be used to make an effective inlet protection device. As always, the objective is temporary, short-term ponding while allowing filtered water to pass through.
35Sediment & Erosion Control KEEPING THE SOIL ON THE SITECheck DamsA check dam is a small, temporary barrier constructed in an open channel, swale, or drainageway. The dam may be constructed of stone, logs, brush, straw bales, or any other material that effectively prevents the flow of water. The primary purpose of check dams is to reduce the velocity of concentrated storm water flows in order to limit erosion. Some settling of water-borne sediment may also occur behind the dam.
36Sediment & Erosion Control KEEPING THE SOIL ON THE SITECheck Dams - ApplicationPrevents erosion in small channels, ditches, and swales draining 10 acres or less.Promotes settling of sediment, but not a primary sediment trapping method.Used during the establishment of grass linings in drainage ditches or channels.
37Sediment & Erosion Control KEEPING THE SOIL ON THE SITECheck Dams - ConstructionDams must be spaced so the toe of the upstream dam is never any higher than the top of the downstream dam.Maximum dam height should be 2 feet. The center of the dam must be 10 to 16 inches lower than either edge, to form a weir for outfall in flood event.Stabilize dams with riprap where appropriate to limit washout and erosion around the periphery of the structure.Use stone 2 to 16 inches in diameter, logs 6 to 8 inches in diameter, sandbags filled with pea gravel, or other sturdy, impervious material to construct the dams.
38Sediment & Erosion Control KEEPING THE SOIL ON THE SITECheck Dams - LimitationsNot to be used in live streams.Not appropriate in channels that drain areas greater than 10 acres.Not to be placed in channels that are already grass-lined unless erosion is expected, as installation may damage vegetation.Require extensive maintenance following high velocity flows.Must remember to remove the dam once soil is stabilized with vegetation.
39Sediment & Erosion Control KEEPING THE SOIL ON THE SITEConcrete Washout ProceduresA central, controlled area should be established on the construction site so concrete byproducts from concrete trucks and other equipment can be contained and disposed of properly, rather than being subject to runoff into catch basins or nearby waterbodies.
40Sediment & Erosion Control KEEPING THE SOIL ON THE SITEStabilized Construction Entrance RoadA primary construction entrance should be identified for access to and from the construction site. This entry should be graveled to prevent sediment and soil from being tracked onto impervious surfaces by vehicles and heavy machinery.
41Sediment & Erosion Control KEEPING THE SOIL ON THE SITEConstruction Entrance Road - CompositionRock size: 2 to 3 inchesFoundation: Geotextile material placed beneath rockThickness: 6 inches minimumPlacement: Rock dumped/spread evenly, compacted by rollerWidth: Minimum of 14 ft.Length: 70 ft. minimum, 30 ft. for single lot
42Sediment & Erosion Control KEEPING THE SOIL ON THE SITESediment BasinsPer Ohio EPA, a sediment settling pond must be established for common drainage locations that serve an area with 10 or more disturbed acres.The pond shall be constructed prior to grading and within 7 days from the start of grubbing, and must continue to function until the development is restabilized.
43Sediment & Erosion Control KEEPING THE SOIL ON THE SITESediment Basins - SizingMust be sized to provide at least 67 cubic yards of storage per acre of total contributing drainage area. Depth must be five feet or less, and total pond length must be at least twice the width.Sediment must be removed from the pond when capacity has been reduced by 40% (typically, that point at which sediment occupies one-half of the basin depth).
44Other ingredients are organic material (5%) and minerals (45%) Know Your Dirt!Air and water make up what percentage of all the ingredients in soil?50%.Other ingredients are organic material (5%) and minerals (45%)
45Know Your Dirt!In a typical year, how many tons of dry soil per acre pass through earthworms living in the soil ?15 tons
46Sediment & Erosion Control KEEPING THE SOIL ON THE SITEOther Sediment & Erosion Control MethodsDUST CONTROLCOVERING SOIL STOCKPILESSTREET CLEANING
47Sediment & Erosion Control KEEPING THE SOIL ON THE SITEAgricultural Sediment & Erosion Control BMPsFILTER STRIPSCRITICAL AREA PLANTINGSDIVERSIONSGRASSED WATERWAYSPASTURE PLANTINGTREE PLANTINGCROP ROTATIONCOVER CROPSSEDIMENT CONTROL BASINSSTREAM PROTECTIONFor information on these and other agricultural soil conservation methods, contact your local Natural Resources Conservation Service district office.
48Sediment & Erosion Control KEEPING THE SOIL ON THE SITEMiami County Engineer’s Office – Aug 2004