HomeMy WebLinkAbout15- Stormwater_Erosion_and_Sediment_Control_Manual1
P.O. Box 1230
Bozeman, MT 59715
Phone: (406)582-2270
Stormwater Erosion and Sediment Control Manual
Stormwater is rain and snowmelt that flows over hard surfaces and
landscapes that does not infiltrate into the ground. Pollutants such as
sediment, garbage, animal wastes, fertilizers, and debris, can be picked up as
water moves over these surfaces. Stormwater then enters curb inlets and is
channeled through a network of underground pipes and is dumped into local
rivers.
Construction site runoff is a significant contributor to local water pollution
and results in extensive infrastructure maintenance costs. This manual
provides information regarding the selection, installation, and maintenance
of erosion and sediment control measures required to keep sediments,
debris, and pollution on-site. The City of Bozeman looks forward to working
with you in keeping our waterways clean and clear.
Figure 1 – Polluted stormwater entering Bozeman Creek.
Figure 2 – Polluted stormwater discharging from a non-compliant construction site. Figure 3 – Improperly protected excavated pile eroding into street inlet.
Figure 5 – Inlet sump and underground pipe filled with sediment from active construction. Figure 4 – Picture of a sediment filled underground stormwater pipe taken by city staff.
Stormwater Department
Version 1 – Created on May 3, 2015
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Table of Contents
Erosion and Sediment Control
1) Straw Wattle.………………………………………………………...……………………………………………………………….…Page 3
2) Silt Fence.………………………………………………………………………………………….……………………………………….Page 5
3) Gravel Approach…………………………………………………....………………………………….………………………………Page 7
Infrastructure Protection
1) Inlet Protection.…………………………………………………………………………………………………………………………Page 8
2) Rock Socks…………………..…………………………………………………………………………………………………………….Page 9
Site De-Watering
1) Filter Sock.………………………………………………………………………………………….……………………………………Page 10
Figure 6 – Example of hand drawn site map with appropriate stormwater erosion and sediment controls.
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Erosion and Sediment Control
Requirement - Applicant is required to protect and contain all disturbed areas preventing soil or debris from entering
into or being tracked onto any road, alley, gutter, storm drain, waterway, or adjacent property. Example stormwater
erosion and sediment control measures include:
1) Straw Wattle - Designed to slow, filter, and disperse the flow of stormwater preventing erosion and site runoff. Made
from straw, flax, or fiber wrapped by degradable poly-propylene netting secured with wooden stakes. Inspections
are required to identify rolls that have been driven over, torn, overwhelmed by sediment build up, or unraveled.
Maintenance, including re-staking, adjustments, clearing of built up debris, fixing gaps, and replacing flattened
sections, is often required. See page 4 for an installation guide.
Straw wattle should be used for the following applications:
Installed along the exterior of disturbed areas that neighbor roads, sidewalks, alleys, wetlands, or waterways.
Secured at the toe of excavated soil stockpiles and landscaping material storage areas.
Straw wattle must meet the following specifications:
Placed with ends turned upslope to prevent runoff from flowing around the straw wattle.
Trenched 2” below grade and secured with wooden stakes every 3’.
Secured with wooden stakes at alternating 45 degree angles.
Joined with an overlap of at least 1’.
Figure 7 – Image of a properly installed straw wattle along a concrete sidewalk. Figure 8 – Map showing the adequate use of straw wattles around the perimeter of a project site.
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Straw Wattle Installation Guide
1) Excavate below grade creating a
depression 2” deep for the
straw wattle to be laid. Pile
excavated debris on the interior
of the job site.
2) Lay straw wattle in the
excavated depression.
3) Drive stakes in at alternating
45 degree angles with spacing
no greater than 3’.
4) Backfill excavated areas 6) Completed straw wattle
installation
5) Compact disturbed areas on
the interior side of the job site.
Vegetation should be
preserved on the exterior side.
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2) Silt Fence – Designed to contain stormwater, soil, and debris preventing erosion and site runoff. Made from porous
fabric trenched into the ground and secured by wooden stakes. Inspections are required to identify silt fence that
has fallen down, torn, split, overwhelmed by sediment build up, or unraveled. Maintenance, including re-securing,
patching, replacement of stakes, and adjustments, is often required. See page 6 for an installation guide.
Silt fence should be used for the following applications:
Installed along the exterior of disturbed areas that neighbor roads, sidewalks, alleys, wetlands, or waterways.
Secured at the toe of excavated soil stockpiles and landscaping material storage areas.
Silt fence must meet the following specifications:
Placed with ends turned upslope to prevent runoff from flowing around the silt fence.
Secured with wooden stakes spaced no more than 10’ apart.
Trenched and buried no less than 6” below grade.
Figure 9 – Image of a properly installed silt fence along a concrete sidewalk. Figure 10 - Map showing the correct location of silt fence along the perimeter of a project site.
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Silt Fence Installation Guide
1) Excavate below grade creating a
6” x 6” square channel. Pile
excavated debris on the interior
of the job site.
2) Lay silt fence along the trench
making sure that the stakes are
facing towards the exterior of
the job site.
3) Drive stakes into the ground on
the exterior side of the
excavated trench.
4) Lay the bottom
fabric inside of the
6” x 6” trench in a U
shape.
5) Backfill the bottom
of the silt fence with
excavated soils.
6) Tighten fence by
pulling and stapling
slack to fence posts.
7) Completed silt fence
installation.
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3) Gravel Approach - Designed to prevent off-site tracking from vehicles entering and leaving construction sites.
Inspections must be completed to ensure gravel approaches are functioning properly and no built up debris are
present. Maintenance, including necessary adjustments, scraping, and or top dressing of additional aggregate, is
often required.
Gravel approaches must meet the following specifications:
Installed using ¾” to 6” crushed rock.
Installed and maintained to a thickness of 12” deep.
Accompanied by barriers limiting access solely to the installed gravel approach.
Figure 12 – Gravel approach example
Figure 14 – Map showing the proper location of a gravel approach.
Figure 11 – Gravel approach example
Figure 13 – Gravel approach example
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Infrastructure Protection
Requirement – Applicant is required to install adequate infrastructure protection measures for all inlets, curb chases,
curb cuts, ditches, or detention ponds receiving runoff from the permitted project site. Example stormwater
infrastructure protection measures include:
1) Inlet Protection - Designed to capture all sediment and debris from site erosion and runoff prior to entering
underground infrastructure. Inspections are required to ensure the protective measure chosen is installed properly
and no built up debris are present. Maintenance, including necessary adjustments and the clearing and disposing of
debris, is often required.
Inlet protection should be used for the following applications:
For downstream inlets receiving runoff from the permitted project site.
In locations where the street, curb, and underground stormwater infrastructure is already in place.
Inlet protection must meet the following specifications:
Installed in combination with other adequate onsite erosion and sediment control measures.
Installed in accordance with individual product requirements.
Figure 17 – Cover inlet protection example Figure 18 – Map showing the proper location of inlet protection. This map does not include all required measures.
Figure 15 – Cover inlet protection example Figure 16 – Cover inlet protection example
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2) Rock Socks - Designed to capture all sediment and debris from site erosion and runoff prior to entering underground
infrastructure. Constructed of 1 ½ minus crushed rock enclosed in a wire mesh or geotextile material. Inspections
are required to ensure the protective measure chosen is installed properly and no built up debris are present.
Maintenance, including necessary adjustments, repair of ripped fabrics, cleaning of sediment, and disposing of
debris, is often required. Note: Only fill 3/4 full with rock to ensure flexibility for adequate curb marriage.
Rock Socks should be used for the following applications:
For downstream inlets receiving runoff from the permitted project site.
In locations where the street, curb, and underground stormwater infrastructure is already in place.
Inlet protection must meet the following specifications:
Installed in combination with other adequate onsite erosion and sediment control measures.
Installed completely surrounding the infrastructure of concern.
Installed with full marriage to road and curb with no gapping.
Trenched 2” deep when used on vegetated surfaces.
Figure 20 – Properly installed rock sock inlet protection example
Figure 19 – Properly installed rock sock inlet protection example
Figure 21 – Properly installed inlet protection example
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Site De- Watering
Requirement – Applicant is required to ensure all construction dewatering is clear and does not pick up sediments or
pollution prior to reaching any stormwater inlet, curb chase, or ditch. Example stormwater site de-watering control
measures include:
1) Filter Socks - Designed to filter discharge water prior to entering any curb line, inlet, ditch, or surface water. Hourly
inspections while de-watering activities are occurring must be completed to ensure the protective measure chosen
is installed properly and the water being discharged from the hose is running clear. Maintenance, including
necessary adjustments, cleaning of filters, and the disposal of debris, must be completed immediately if any issues
are found. All de-watering activities may require additional permitting from the Montana Department of
Environmental Quality.
Filter socks must meet the following specifications:
Installed whenever de-watering is occurring.
Placed on an impervious, vegetated, or rip-rapped surface.
Set in a location that does not allow discharged water to pick up sediment in curb lines or cause erosion
of disturbed areas
Figure 25 – Filter sock example Figure 24 – Filter sock example
Figure 22 – Filter sock example Figure 23 – Filter sock example