To Learn More
To find out more about the storm water permit
program, or to get copies of the Construction
General Permit, the Notice of Intent application
form, or other related guidance materials, check out
the following EPA's websites:
www.epa.gov/r10earth/stormwater.htm
www.epa.gov/npdes/stormwater/cgp
Contact EPA:
Jeanne O'Dell
Region 10 Storm Water Program
(800) 424-4372, extension 6919
Email: odell.jeanne@epa.gov
For other information on impaired waterways,
contact:
Idaho Department of Environmental Quality
Boise Regional Office 208-373-0550
Pocatello Regional Office 208-236-6160
Idaho Falls Regional Office 208-528-2650
Twin Falls Regional Office 208-736-2190
Coeur d'Alene Regional Office .... 208-769-1422
Lewiston Regional Office 208-799-4370
For information on Best Management Practices:
Idaho Department of Environmental Quality's
Catalog of Stormwater Best Management
Practices for Idaho Cities and Counties:
www.deq.state.id.us/water/water1.htm
Go to Wastewater, and scroll to Stormwater
Ada County Highway Department:
www. achd.ada.id.us
Scroll to Stormwater
Boise City Storm Water Design Manual and
Ordinance:
www.cityofboise.org/pds/erosion.shtml
Other Resources:
International Erosion Control Association:
www.ieca.org
Idaho Associated General Contractors:
www.agcidaho.org
Click on Environmental Issues
Partners for Clean Water, Boise/Ada County:
www.partnersforcleanwater.org
Note: Website addresses listed are case sensitive.
EPA-910-F-03-002
&EFA
August 2003
Notice: The statements in this document are intended solely as
guidance to aid regulated entities in complying with the Clean Water
Act's storm water requirements. The guidance is not a substitute for
reading the Clean Water Act and its implementing regulations and
understanding all its requirements as they apply to your facility. This
guidance does not constitute rulemaking by the EPA and may not be
relied on to create a substantive or procedural right or benefit
enforceable, at law or in equity, by any person. EPA may decide to
update this guide without public notice to reflect changes in EPA's
approach to implementing the Clean Water Act. This document
reflects information available in EPA's NPDES General Permit for
Storm Water Discharges from Large and Small Construction
Activities.
United States
Environmental Protection
Agency
Region 10
1200 Sixth Avenue
Seattle WA 98101-1128
Construction
Projects in Idaho
Need Erosion and
Sediment Controls
The U.S. Environmental Protection Agency (EPA)
has issued a general permit containing
requirements for construction activities in Idaho
for sites where runoff may enter nearby surface
water.
If you are planning a construction project that will
disturb more than one acre of land, you are
required to have permit coverage. You should
also have erosion and sediment controls in place
for runoff from your site before construction
begins.
The information in this brochure summarizes your
responsibilities for permit coverage and for
erosion and sediment controls, as required under
the federal Clean Water Act to limit water
pollution from construction sites.
Erosion and sediment control practices are only
as good as their installation and maintenance.
Tips for Managing Storm Water
Protect Natural Features and Minimize Erosion
• Minimize clearing and amount of exposed soil.
• Leave more vegetation in place and only disturb the
smallest area of land possible.
• Protect streams, wild woodland, and wetlands from
construction activity by fencing the areas. Divert
runon/runoff away from exposed areas.
• Use slope breaks, temporary lined diversion ditches
or retention structures to slow runoff.
Covering dirt piles reduces storm water runoff velocity.
Terracing can be used to slow runoff. Lined diversion ditches direct
flow away from exposed areas toward stable portions of the site.
Construction Phasing
• Sequence construction activities to minimize the
amount of time soils remain disturbed.
• Install sediment controls before grading begins.
• Schedule or limit grading to small areas.
• Schedule construction so that large areas of bare soil
are exposed only during the dry season.
• Use temporary mulching, seeding or other ground
coverings on exposed areas, including all dirt
stockpiles.
• Stabilize the area immediately after the land has
been graded to its final contour.
Exposed soils are very vulnerable to erosion. Mulch or other
ground cover protects surfaces from wind and storm water
erosion, as well as allowing vegetative growth.
Silt Fencing
• Bury the bottom of the silt fence in the ground.
• Use stakes to support the back of the silt fence.
• Silt fences or other sediment traps should
capture sediment near its source.
• Inspect and maintain the fence after each
storm.
• Don't place the silt fence in the middle of a
waterway or use them as check dams.
• Make sure storm water is not flowing around or
under the silt fence.
Silt fences prevent the off site transport of sediment at
construction sites.
In phased construction, completed portions are permanently
stabilized before other areas are disturbed.
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More Tips for
Managing Storm Water
Controlling Pollution
• Maintain a clean and orderly construction site to
prevent storm water contamination from:
- hazardous materials
- cement/concrete truck washout
- oil spills
- waste and debris
Construction Entrances
• Install measures to remove dirt from tires of vehicles
before they enter a paved roadway.
• Keep entrances from becoming buried in soil.
• Stabilize entrances and exits with rock or other
materials.
Stabilized construction entrances allow dirt to be removed from tire
treads as trucks leave construction sites.
The Construction General Permit (CGP)
The Clean Water Act requires operators of construction
sites to obtain permit coverage to discharge storm
water to a water body or to a municipal storm sewer.
In Idaho, EPA has issued a general permit for storm
water discharges from construction sites.
If a construction project disturbs more than one acre of
land (or is part of a larger common development that
will disturb more than one acre), the operator is
required to apply for permit coverage from EPA after
developing a site-specific Storm Water Pollution
Prevention Plan.
For more information, please call Jeanne O'Dell at
206-553-6919 or toll free at 1-800-424-4372, extension
6919.
EPA's Inspection Plans in Idaho
As part of our effort to restore and maintain the
quality of Idaho's lakes, rivers, and streams, EPA
is increasing its inspections at construction sites.
If a site is found to be out of compliance with the
permit or the Clean Water Act, EPA has a range
of formal and informal responses, including:
warning letters; compliance orders; and penalties.
Penalties for not complying with the permit
requirements are determined on a case-by-case
basis and can range from $2,000 to $27,500 per
day for each violation. Criminal prosecution is
also an option if operators are caught knowingly
violating the Clean Water Act.
storm water from construction sites and to get a storm
water permit. Adequate pollution controls must be in
place to prevent storm water runoff from moving soil
and other pollutants into a nearby water body.
Improper management and disposal of wastes can result in
polluted storm water discharges.
Construction Activities That May Need
a Storm Water Permit
• Clearing & grubbing, except silviculture
• Grading
• Excavation and filling
• Road and bridge building and installation of
other infrastructure
Sediment is Usually the Main Pollutant
of Concern in Storm Water from
Construction Sites
Too much sediment in the water can destroy
aquatic habitat; interfere with fish rearing, feeding,
migration and spawning; interfere with
recreational uses; and threaten drinking water
supplies. Along with sediment, eroding soils also
release nutrients which act as pollutants once
they enter waterways, causing algae blooms and
low oxygen levels.
These pollutants affect water quality and can be
harmful to humans, fish and wildlife habitat. For
this reason, the federal Clean Water Act requires
construction operators to have erosion and
sediment controls in place before discharging
Lined sediment basins are used to collect runoff from disturbed areas
on construction sites and allow heavier solids to settle out.
Other Common Pollutants in Construction
Site Runoff
Construction materials and wastes can also release
pollutants, especially metals and organic chemicals.
Many of these are toxic to aquatic organisms and other
life. These toxins include:
• Pesticides
• Solid and sanitary wastes
• Oil and grease (from fuel containers and equipment)
• Phosphorus and nitrogen (from soil and artificial
fertilizers)
• High pH (from concrete truck washout)
• Metals (from pipe shavings, solder, etc.)
• Construction chemicals and debris (from poor
housekeeping)
Storm Water Pollution Prevention Plan
EPA's permit requires operators to develop a site-
specific Storm Water Pollution Prevention Plan
(SWPPP). As a condition of permit coverage, the
operator must document the erosion, sediment and
pollution controls they intend to use, inspect those
controls periodically, and maintain the best
management practices (BMPs) through the life of the
project. Operators must also update the plan as site
conditions change, and keep a copy of the plan on-site.
There are many cost effective ways to prevent soil
erosion and manage storm water runoff. Operators
may use the most appropriate techniques for the site to
protect water quality.
An ounce of prevention is worth a pound of
cure! It's far more efficient and cost-
effective to prevent pollution than it is to try
to correct problems later. Installing and
maintaining simple BMPs and pollution
prevention techniques on site can greatly
reduce the potential for storm water
pollution and can also save you money!
Constructed wetlands can be an effective - and attractive -
post-construction storm water control.
Other Related Requirements
The EPA Construction General Permit (Part 9)
also contains information relating to Total
Maximum Daily Loads (TMDL) for polluted or
impaired water bodies in Idaho. There may be
specific requirements you must follow to be
consistent with any local pollutant allocations.
Check with your local Idaho Department of
Environmental Quality office for more information
on TMDLs.
Check with your local authority regarding any
applicable rules about how to design your
construction project. Impervious surfaces may
affect storm water quality and quantity. Many
communities throughout Idaho are currently
developing rules for post-construction storm
water management.
Discharging storm water underground requires
prior approval from the Idaho Department of
Water Resources (IDWR). Call (208)327-7956
for more information.
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