georgia dot’s revised stormwater manual session 1 gdot...•new npdes construction general permit...
TRANSCRIPT
Georgia DOT’s Revised
Stormwater Manual
Georgia Association of Floodplain ManagementAnnual Technical Conference
March 2014
Presentation Topics
• Purpose of the Manual Update• Research Conducted• What’s New
– Policies– Stormwater Planning– Post-Construction Best
Management Practices (BMPs)– Infeasibility
• Status
Source: WSDOT
• New NPDES Construction General Permit– Issued September 24, 2013
• New NPDES Municipal Separate Storm Sewer (MS4) Permit– Issued January 3, 2012
• New GDOT Stormwater Policy• Revised Manual for Erosion and
Sediment Control– Issued January 1, 2014
• Manual Modernization
Purpose of the Manual Update
Purpose of the Manual Update
New GDOT MS4 Permit requirements:• Address post-construction stormwater runoff• Implement checklists
– Post-construction BMPs– Low Impact Development (LID)/Green
Infrastructure (GI) practices• Incorporate standard six minimum control
measures
Purpose of the Manual Update
Key Policy Updates Include:• Design of Post-Construction BMPs• MS4 Permit
Afforded GDOT the option of adopting the GSWMM or developing their own manual.
• LID/GI Requirements• US Army Corps of Engineers
– Fish Passage– 404 Nationwide Permit Regional Conditions
Proposed Scope of the Manual
Policy BasedIncorporate New MS4
Permit Requirements
Georgia Specific
Linear (Highway) Focused
Research Conducted
GDOT document review:• MS4 Permit • Current Drainage Manual• Policies• Standards, Details, and SpecificationsGeorgia document review:• Georgia Stormwater Management Manual • Coastal Stormwater Supplement • Georgia Erosion Control Manual
Research Conducted
State of the Practice/Literature Review:• National Sources (FHWA, AASHTO, EPA, etc.)• State policies, practices, and BMPs
– North Carolina– Tennessee– South Carolina– Washington– Maryland– Pennsylvania Source: FHWA
Revised Table of Contents
• Ch. 1 - Introduction• Ch. 2 - Agency Coordination and Regulations• Ch. 3 - Stormwater Planning• Ch. 4 - Hydrology & Hydraulics• Ch. 5 - Channels• Ch. 6 - Pavement Drainage• Ch. 7 - Storm Drain Design• Ch. 8 - Culverts• Ch. 9 - Erosion and Sediment Control Guidelines• Ch. 10 - Post-Construction Stormwater Design Guidelines• Ch. 11 - Stream & Wetland Restoration Concepts• Ch. 12 - Bridge Hydraulic Design Criteria• Ch. 13 - Bridge Deck Drainage Systems
Permitting Agencies &
Coordination
Hydrology &
Hydraulics
Construction Stormwater
Requirements
Stormwater Planning
Post-Construction Stormwater
Requirements
Stormwater Planning
Incorporate stormwater early to avoid project delays
Stormwater Planning
Public SafetyMotorists, pedestrians, maintenance personnel
Protection of GDOT facilitiesReducing erosive damage
Protection of Private Property– Flood damage– Upstream & Downstream affects
Protection of the surrounding environmentHarming receiving waters, ecosystem, or wildlife
Initial Planning Concepts
1. Avoidance: avoid disturbing environmentally sensitive areas (e.g. changing the roadway alignment to avoid these areas)
• Wetlands • Rivers• Lakes• Streams• Floodplains• Sensitive habitats
Initial Planning Concepts
2. Minimization: minimize the disturbance required for the project (both immediate and long term)
• Buried culverts or bridges • Selective clearing practices
Source: NPS
Initial Planning Concepts
3. Footprint reduction: reduce the roadway footprint by considering different alternatives
• Reduce the lane width• Reduce median width• Reduce shoulder width
Source: www.PPS.org
Other Planning Concepts
Context Sensitive Solutions • Planning involving all stakeholders • Design enhances scenic, aesthetic, historic, and
environmental resources while improving safety and other fundamental design requirements
LID/GI Practices• Strongly encouraged and are required when feasible• Must be considered during the design phase
LID and GI Practices
LID/GI Checklist• Design Considerations• Design Documentation• Inspection &
Maintenance Responsibility
Submitted with plans at milestone submittals
Submitted to EPD with MS4 annual report
Primary Planning Resources• GDOT Stormwater Manual• GDOT Policy• Georgia Stormwater Management Manual &
Coastal Supplement
Post-Construction Stormwater
1. Filter Strip2. Grass Channel3. Enhanced Swales4. Infiltration Trench5. Sand Filter6. Dry Detention Basin
7. Wet Detention Pond 8. Stormwater Wetland9. Bioslope10. Open Graded Friction
Course (OGFC)11. Bioretention
Post-Construction Stormwater
GDOT’s current list of preapproved BMPs (Structural)
Post-Construction Stormwater
Applies to new projects that are:
• Within MS4 permitted areas areas (shown on the map)
• Linear roadway projects disturbing >1 acre or site development projects adding more than 5,000 square feet of impervious area
Post-Construction Stormwater
Exclusions include:• Maintenance and safety improvements that do not
disturb > 1 acre (shoulder building, sound barrier construction, etc.)
• Non-GDOT owned or operated (maintained) roadways
Source: GDOT
Post-Construction Stormwater
Exclusions include:• Sites where runoff exits the R/W as sheet flow and
does not cause instability, erosion, or flooding.• Scenarios where individual post-construction BMPs
are deemed infeasible.
Infeasibility Criteria
BMP cost (>10%)
Schedule delay (>90 days)
T&E species impact
Community/cultural resource damage
Residence or business
displacement
State, Federal Law, or
regulation violation
Infeasibility Report (GDOT template) to include the following information:
• Reason
• Location
• Alternatives analysis
• Cost analysis
Status
Under final review by GDOT
and FHWA
MS4 Permit elements must be
reviewed and approved by EPD
Anticipated Release in the 2nd quarter of
2014
Stay Tuned…
Questions?
Source: GDOT
Brad McManus, PE – GDOT Office of Design Policy & Support [email protected]
Charles Crowell, PE – [email protected]
Contact Information