creating a storm water pollution prevention plan for construction activities

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


Assessment:

Measure the site area

Determine the drainage areas

Calculate the runoff coefficient


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


Control Selection / Plan Design Continued:

Prepare an inspection and maintenance plan

Prepare sequence of major activities

Incorporate State or local Requirements


Certification / Notification:

Certify the plan

Submit Notice of Intent

Plan location


Construction / Implementation:

Implement controls

Inspect and maintain controls

Update / change the plan

Report releases of reportable quantities


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


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


Prepare Pollution Prevention Site Map

Approximate slopes after grading

Indicate areas of soil disturbance

Indicate drainage patterns

Assessment

Measure site area

Indicate the total site area and the area which will be disturbed

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


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


Select storm water management controls

Storm water detention structures (including wet ponds)

Storm water retention structures

Open vegetated swales

Natural depressions

Infiltration measures


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


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


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


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


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


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


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


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


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


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


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


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

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


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

creating a storm water pollution prevention plan for construction activities

Documents