Creating a Storm Water Pollution Prevention Plan For Construction Activities.
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Transcript of Creating a Storm Water Pollution Prevention Plan For Construction Activities.
Creating a Storm Water Pollution Prevention Plan
A requirement of the construction storm water permit is to develop a storm water pollution prevention plan (SWPPP) before construction activities begin. The SWPPP should be complete before submitting the Notice of Intent (NOI). The following slide show will step through each item that is to be addressed in the SWPPP. By following this guide, you will be able to develop a SWPPP that fulfills the requirements of the Arkansas Department of Environmental Quality.
SWPPP Organization Guideline
Site Evaluation and Design Development:
Collect site information
Develop Site Plan
Prepare pollution prevention site map
SWPPP Organization Guideline
Assessment:
Measure the site area
Determine the drainage areas
Calculate the runoff coefficient
SWPPP Organization Guideline
Control Selection / Plan Design:
Select erosion and sediment controls
Select other controls
Select storm water management controls
Indicate the location of controls on the site map
Site map requirements
SWPPP Organization Guideline
Control Selection / Plan Design Continued:
Prepare an inspection and maintenance plan
Prepare sequence of major activities
Incorporate State or local Requirements
SWPPP Organization Guideline
Certification / Notification:
Certify the plan
Submit Notice of Intent
Plan location
SWPPP Organization Guideline
Construction / Implementation:
Implement controls
Inspect and maintain controls
Update / change the plan
Report releases of reportable quantities
SWPPP Organization Guideline
Final Stabilization / Termination
Final stabilization
Notice of Termination
SWPPP
The following is a step-by-step description of each item in the organizational list that was previously supplied. By addressing each item in the list, an acceptable SWPPP can be developed that meets ADEQs basic criteria.
Site Evaluation and Design
Collect site information
Existing conditions site map
Soils information
Runoff water quality
Name of receiving stream / water
Rainfall data
Site Evaluation and Design
Develop Site Plan
Disturb the smallest vegetated area possible
Keep the amount of cut and fill to a minimum
Limit impacts to sensitive areas such as:
Steep and / or unstable slopes Surface waters, including wetlands Areas with soil is likely to erode Existing drainage channels
Site Evaluation and Design
Prepare Pollution Prevention Site Map
Approximate slopes after grading
Indicate areas of soil disturbance
Indicate drainage patterns
Assessment
Determine the Drainage Area
Measure the size of each drainage basins for each point where concentrated flow will leave the site
Use the calculated concentrated flow to determine the appropriate sediment control measures
Assessment
Calculate the Runoff CoefficientDevelop an estimate of the development’s
impact on runoff after construction is complete. This can be done by estimating a runoff coefficient for post-construction conditions
Q = (C) * (I) * (A)
where
Q = the rate of runoff from an areaC = partial amount of the total rainfall
that will become runoff I = rainfall intensity, and
A = the area of the drainage basin
Assessment Continued
Calculate the Runoff Coefficient Continued Calculating a “weighted” runoff
coefficient:
where
A = acres and
C = coefficient
Assessment Continued
BusinessDowntown AreasNeighborhood Area
ResidentialSingle-family areasMultiunits, detachedMultiunits, attached
Residential (suburban)
Apartment dwelling areas
Industrial Light AreasHeavy Areas
Parks, cemeteries
Playgrounds
Railroad yard areas
Unimproved areas
Streets AsphaltConcreteBrick
Drives and walks
Roofs
Lawns - course textured soil (greater than 85% sand)Slope: Flat, 2%
Average, 2-7%Steep, 7%
Lawns - fine textured soil (greater than 40% clay)Slope: Flat, 2%
Average, 2-7%Steep, 7%
Description of Area Runoff Coefficients
0.70 - 0.950.50 - 0.70
0.30 - 0.500.40 - 0.600.60 - 0.75
0.25 - 0.40
0.50 - 0.70
0.50 - 0.800.6 - 0.90
0.10 - 0.25
0.75 - 0.95
0.20 - 0.35
0.20 - 0.40
0.10 - 0.30
0.70 - 0.95
0.18 - 0.220.25 - 0.35
Typical "C" Values (ASCE 1960)
0.05 - 0.100.10 - 0.150.15 - 0.20
0.13 - 0.17
0.80 - 0.950.70 - 0.85
0.75 - 0.85
Control Selection / Plan Development
Select erosion and sediment controls
Stabilization measures for disturbed areas
Structural controls to divert runoff and remove sediments
Erosion and sediment controls can include temporary or permanent measures
Control Selection / Plan Development
Select other controls
Proper waste disposal
Control of offsite vehicle tracking
Compliance with applicable State or local waste disposal
Sanitary sewer or septic system regulations
Control of allowable non-storm water discharges
Control Selection / Plan Development
Select storm water management controls
Storm water detention structures (including wet ponds)
Storm water retention structures
Open vegetated swales
Natural depressions
Infiltration measures
Control Selection / Plan Development
Indicate location of controls on the site map
Areas of permanent seeding
Areas of sod stabilization
Silt fence
Straw bale barrier
Earth dikes
Brush barriers
Drainage swales
Sediment traps
Control Selection / Plan Development
Indicate location of controls on the site map
Pipe slope drains
Level spreaders
Storm drain inlet protection
Reinforced soil retaining systems
Gabions
Temporary or permanent sediment basins
Stabilized construction entrances
Control Selection / Plan Development
Site map requirements
Drainage patterns
Approximate slopes after grading
Area of soil disturbance
Location of major structural and nonstructural controls
Areas where stabilization practices are expected to occur
Location of surface waters
Control Selection / Plan Development
Prepare an inspection and maintenance plan
Qualified personnel shall inspect disturbed areas of the construction site at least once every seven calendar days and within 24 hours of the end of a storm that
is 0.5 inches or greater
A description of procedures to maintain in good condition and effective operating condition
Vegetation Erosion and sediment control measures Other protective measures identified in the
site plan
Control Selection / Plan Development
Prepare sequence of major activities
The sequence of major activities should include a timeline for:
Construction of control measures Earth disturbing construction activities Maintenance activities for control
measures in the order in which they will occur
Down slope and side slope perimeter controls should be installed before the land disturbing activity occurs
Do not disturb an area until it is necessary for construction to proceed
Cover or stabilize as soon as possible
Control Selection / Plan Development
Prepare sequence of major activities continued
The sequence of major activities should include a timeline for:
Time activities to limit impact form seasonal climate changes or weather events
Construction of infiltration measures should be delayed to the end of the project when upstream drainage areas have been stabilized
Control Selection / Plan Development
Incorporate state or local requirements
Permittees shall incorporate all applicable requirements specified in State or local sediment and erosion control plans or permits, or storm water management plans or permits. This should include requirements such as
City ordinances City grading permit requirements
Certification and Notification
Certify the Plan
Your NPDES storm water permit requires that authorized representative(s) of the operator(s) sign and certify the plan. The authorized representative(s) should be individuals at or near the top of the management chain, such as:
The president Vice-president General partner, who has been delegated
the authority to sign and certify this type of document
Certification and Notification
Notice of Intent
You are required to submit a Notice of Intent (NOI) prior to commencement of construction
The NOI cannot be submitted until the SWPPP has been prepared
Certification and Notification
Plan location
SWPPPs for construction activities shall be maintained onsite of the activity unless the Director, or authorized representative, the operator of a large or medium MS4, or a State or local sediment and control agency requests that the plan be submitted.
Permittees should keep a copy of the plan at the construction site until the site is finally stabilized
Permittees are required to keep the plan, all reports and data for at least three years after the project is complete
Construction / Implementation
Implement controls
The controls should be constructed or applied in accordance with State or local standard specifications
If there are no State or local specifications for control measures then the controls should be constructed in accordance with good engineering practices
Improperly installed controls can have little or no effect and may actually increase the pollution of storm water
Construction / Implementation
Inspect and maintain controls Inspection should be performed at the
frequency specified in the SWPPP and / or the permit
The inspector should note any damage or deficiencies in the control measures in an inspection report
The inspector should correct damage or deficiencies as soon as practicable after the inspection
The operator should keep records of the construction activity on the site, such as:
Dates when major grading activities occur in a particular area
Dates when construction activities cease in an area
Dates when an area is stabilized
Construction / Implementation
Update / change plans
SWPPPs are developed based on site-specific features and functions. Where there are changes in design, construction, operation, or maintenance, and that change will have a significant effect on the potential for discharging pollutants in storm water at a site, the SWPPP should be modified by the permittee to reflect the changes and new conditions
The permittee is required to update the plan as necessary to reflect any changes onsite which may affect the potential for discharges of pollutants from the site
Construction / Implementation
Releases of reportable quantities
If the construction site has a release of a hazardous substance or of oil in an amount which exceeds a reportable quantity (RQ) as defined at 40 CFR Part 110, 40 CFR Part 117, or 40 CFR Part 302, then the permittee shall do several things:
The person in charge of the site at the time of the spill shall call the National Response Center to report the spill – 800-424-8802
Within 14 days after the release is detected, modify the site SWPPP
Within 14 days of the release, submit a written description of the release to ADEQ
Final Stabilization / Termination
Final stabilization
A site can be considered finally stabilized when all soil disturbing activities at the site have been completed and a uniform perennial vegetative cover with a density of 70 percent for the unpaved areas and areas not covered by permanent structures has been established or equivalent permanent stabilization measures have been employed
Final Stabilization / Termination
Notice of Termination
The Notice of Termination (NOT) is the final task required to comply with the requirements of an NPDES storm water permit for a construction activity. The NOT form is sent to the permittee with the confirmation letter. Additional NOTs can be obtained by contacting the storm water staff at ADEQ