Presentation on theme: "KEEPING THE SOIL ON THE SITE Miami County Engineer’s Office – Aug 2004."— Presentation transcript:
KEEPING THE SOIL ON THE SITE Miami County Engineer’s Office – Aug 2004
KEEPING THE SOIL ON THE SITE What 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.
KEEPING THE SOIL ON THE SITE Why is Sediment & Erosion Control Necessary? 1.There is a legal requirement to practice sediment & erosion control on most construction sites. 2.Proper erosion controls will prevent expensive, time-consuming rework of finish-grade landscape areas after heavy rains. 3.Keeping soil on the construction site will prevent polluted runoff from entering local streams, lakes, and rivers. 4.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.
KEEPING THE SOIL ON THE SITE It’s the Law Phase 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.
KEEPING THE SOIL ON THE SITE Pay Now, or Pay Later Sediment 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.
KEEPING THE SOIL ON THE SITE Clean Water is Everyone’s Business Storm 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.
KEEPING THE SOIL ON THE SITE Miami County Commissioners Bethel, Concord, Monroe, & Union Townships Miami Conservancy District Miami Soil & Water Conservation District Miami County Health Department Miami County Planning & Zoning Miami County Engineer’s Office Local Watershed Groups OSU Extension Ohio Environmental Protection Agency You! Local Initiatives
On average, how many years does it take to form one inch of topsoil? Around 500 years
The scientific study of soil is called what? Pedology
KEEPING THE SOIL ON THE SITE Sediment & Erosion Control Methods Construction Project Phasing Mulching & Seeding Soil Bank Stabilization Silt Fence Installation Inlet Protection Ditch Checks Concrete Washout Procedures Construction Entrance/Exit Road Composition Sediment Basins
KEEPING THE SOIL ON THE SITE Sediment & Erosion Control First things First Sediment 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. =
KEEPING THE SOIL ON THE SITE Construction Project Phasing Completion 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.
KEEPING THE SOIL ON THE SITE Construction 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.
KEEPING THE SOIL ON THE SITE Mulching & Seeding EPA 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.
KEEPING THE SOIL ON THE SITE Mulching & Seeding (continued) ADVANTAGESDISADVANTAGES 1.Low material expense 2.Low manpower costs 3.Material readily available 4.Easy to apply 5.Straw works well as seed bedding if kept moist 1.Does not hold to sloped soils unless an emulsion tackifier is added. 2.Must be kept moist for seed germination 3.Can be blown off-site by passing cars, wind, or large storm event. 4.Straw waste can contribute to site drainage problems. Method: Straw Mulch over Grass Seed Approximate Cost: $150 per 5000 sq ft coverage
KEEPING THE SOIL ON THE SITE Mulching & Seeding (continued) ADVANTAGESDISADVANTAGES 1.Seed, mulch, fertilizer & water applied simultaneously 2.Low manpower costs, rapid application 3.Holds well to sloped soils 4.Less affected by wind forces 5.Mulch works well as seed bedding & holds moisture longer than straw 1.Can be affected by large storm events 2.Must be kept moist for seed germination 3.Requires water source in order to be applied 4.Success of germination is affected greatly by the manner in which the hydroseed is applied Method: Hydroseeding Approximate Cost: $300 per 5000 sq ft coverage
KEEPING THE SOIL ON THE SITE Mulching & Seeding (continued) ADVANTAGESDISADVANTAGES 1.Seed, mulch & fertilizer applied simultaneously 2.Holds well to sloped soils 3.Least affected by wind forces & rain events 4.Blanket works well as seed bedding 1.Labor intensive installation 2.Must spike down blanket with non- biodegradable materials 3.More costly than other mulch/seed applications 4.More subject to on-going service & maintenance Method: Straw/Seed Blankets Approximate Cost: $400 per 5000 sq ft coverage
KEEPING THE SOIL ON THE SITE Mulching & Seeding (continued) ADVANTAGESDISADVANTAGES 1.Immediate erosion/sediment control 2.Holds well to sloped soils 3.Unaffected by wind forces & rain events 4.Eliminates need for installation of intermediary sediment and erosion control BMPs 5.Low maintenance and/or rework 1.The most labor intensive installation 2.Must be kept moist to allow sod to bond to soil substrate 3.Will be cost prohibitive for most projects 4.Materials may not be readily available Method: Sod Approximate Cost: $675 per 5000 sq ft coverage
Soil scientists have identified more than how many thousands of soil types in the United States? More than 70,000
An annelid is an animal that lives in the soil. What is its common name? An earthworm
KEEPING THE SOIL ON THE SITE Soil Bank Stabilization To 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.
KEEPING THE SOIL ON THE SITE Silt Fence Installation Silt 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.
KEEPING THE SOIL ON THE SITE Silt Fence Installation (continued) SLOPE LENGTH Drainage Area Prevent flow around ends by bringing up slope Set away from steep slope or toe of fill SLOPESLOPE LENGTH < 50:1250 FT 50:1 – 10:1125 FT 10:1 – 5:1100 FT 5:1 – 3:175 FT 3:1 – 2:150 FT > 2:125 FT
KEEPING THE SOIL ON THE SITE Silt Fence Installation - Summary Silt fence needs to be: Installed on the contour Trenched to a depth of 6” Stretched until tight All joining sections rolled Stakes on downslope side, from 4’ to 6’ apart Top of fence 16” above ground Ends of fence elevated
KEEPING THE SOIL ON THE SITE Silt Fence - Maintenance Regular maintenance is needed to assure the silt fence continues to function properly: Inspect installation weekly and after each heavy rain Re-anchor where needed Remove accumulated sediment as necessary, to restore capacity Repair any tears in the geotextile material
KEEPING THE SOIL ON THE SITE Silt Fence – Improper Uses Silt 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.
KEEPING THE SOIL ON THE SITE Silt Fence – Rule of Thumb If it doesn’t pond water, it doesn’t work.
These are primarily responsible for keeping soil in its place? Roots
A handful of soil contains more of these than the number of people alive on Earth? Bacteria
KEEPING THE SOIL ON THE SITE Inlet Protection Storm 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.
KEEPING THE SOIL ON THE SITE Inlet Protection - Types Various 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.
KEEPING THE SOIL ON THE SITE Inlet Protection - Geotextile These units use silt fence fabric and wire mesh, wrapped around a metal or wooden frame, as a means to pond water around inlets.
KEEPING THE SOIL ON THE SITE Inlet Protection – Manufactured Units Some 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.
KEEPING THE SOIL ON THE SITE Inlet Protection Using Construction Materials Gravel, 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.
KEEPING THE SOIL ON THE SITE Check Dams A 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.
KEEPING THE SOIL ON THE SITE Check Dams - Application Prevents 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.
KEEPING THE SOIL ON THE SITE Check Dams - Construction Dams 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.
KEEPING THE SOIL ON THE SITE Check Dams - Limitations Not 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.
KEEPING THE SOIL ON THE SITE Concrete Washout Procedures A 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.
KEEPING THE SOIL ON THE SITE Stabilized Construction Entrance Road A 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.
KEEPING THE SOIL ON THE SITE Construction Entrance Road - Composition Rock size: 2 to 3 inches Foundation:Geotextile material placed beneath rock Thickness: 6 inches minimum Placement:Rock dumped/spread evenly, compacted by roller Width:Minimum of 14 ft. Length:70 ft. minimum, 30 ft. for single lot
KEEPING THE SOIL ON THE SITE Sediment Basins Per 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.
KEEPING THE SOIL ON THE SITE Sediment Basins - Sizing Must 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).
Air and water make up what percentage of all the ingredients in soil? 50%. Other ingredients are organic material (5%) and minerals (45%)
In a typical year, how many tons of dry soil per acre pass through earthworms living in the soil ? 15 tons
KEEPING THE SOIL ON THE SITE Other Sediment & Erosion Control Methods DUST CONTROL COVERING SOIL STOCKPILES STREET CLEANING
KEEPING THE SOIL ON THE SITE Agricultural Sediment & Erosion Control BMPs FILTER STRIPS CRITICAL AREA PLANTINGS DIVERSIONS GRASSED WATERWAYS PASTURE PLANTING TREE PLANTING CROP ROTATION COVER CROPS SEDIMENT CONTROL BASINS STREAM PROTECTION For information on these and other agricultural soil conservation methods, contact your local Natural Resources Conservation Service district office.
KEEPING THE SOIL ON THE SITE Miami County Engineer’s Office – Aug 2004