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.
Local Initiatives
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!
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)
Method: Straw Mulch over Grass Seed
ADVANTAGES
1.
2.
3.
4.
5.
Low material expense
Low manpower costs
Material readily available
Easy to apply
Straw works well as seed bedding if kept moist
DISADVANTAGES
1.
2.
3.
4.
Does not hold to sloped soils unless an
emulsion tackifier is added.
Must be kept moist for seed germination
Can 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
KEEPING THE SOIL ON THE SITE
Mulching & Seeding (continued)
Method: Hydroseeding
ADVANTAGES
1.
2.
3.
4.
5.
Seed, mulch, fertilizer & water applied
simultaneously
Low manpower costs, rapid application
Holds well to sloped soils
Less affected by wind forces
Mulch works well as seed bedding & holds
moisture longer than straw
DISADVANTAGES
1.
2.
3.
4.
Can be affected by large storm events
Must be kept moist for seed germination
Requires water source in order to be applied
Success of germination is affected greatly by
the manner in which the hydroseed is applied
Approximate Cost: $300 per 5000 sq ft coverage
KEEPING THE SOIL ON THE SITE
Mulching & Seeding (continued)
Method: Straw/Seed Blankets
ADVANTAGES
1.
2.
3.
4.
Seed, mulch & fertilizer applied
simultaneously
Holds well to sloped soils
Least affected by wind forces & rain events
Blanket works well as seed bedding
DISADVANTAGES
1.
2.
3.
4.
Labor intensive installation
Must spike down blanket with nonbiodegradable materials
More costly than other mulch/seed applications
More subject to on-going service &
maintenance
Approximate Cost: $400 per 5000 sq ft coverage
KEEPING THE SOIL ON THE SITE
Mulching & Seeding (continued)
Method: Sod
ADVANTAGES
1.
2.
3.
4.
5.
Immediate erosion/sediment control
Holds well to sloped soils
Unaffected by wind forces & rain events
Eliminates need for installation of intermediary
sediment and erosion control BMPs
Low maintenance and/or rework
DISADVANTAGES
1.
2.
3.
4.
The most labor intensive installation
Must be kept moist to allow sod to bond to soil
substrate
Will be cost prohibitive for most projects
Materials may not be readily available
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
SLOPE
LENGTH
< 50:1
250 FT
50:1 – 10:1
710
125 FT
708
10:1 – 5:1
100 FT
5:1 – 3:1
75 FT
706
3:1 – 2:1
50 FT
704
> 2:1
25 FT
702
710
SLOPE
LENGTH
Drainage Area
Prevent flow around ends
by bringing up slope
700
Set away from steep
slope or toe of fill
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
• TREE PLANTING
For
informationAREA
on these
and other agricultural
soil conservation
•CROP
ROTATIONmethods,
•CRITICAL
PLANTINGS
contact your local Natural Resources Conservation Service district office.
•DIVERSIONS
•COVER CROPS
•GRASSED WATERWAYS
•SEDIMENT CONTROL BASINS
•PASTURE PLANTING
•STREAM PROTECTION
KEEPING THE SOIL ON THE SITE
Miami County Engineer’s Office – Aug 2004