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2020 NC Erosion & Sediment Control Design Workshop
Webinar Series
#3 – Oct. 20, 2020 – Transitioning E&SC Between Phases
Karyn Pageau, EI, CPESCWake County
About Karyn:
• I enjoy all things E&SC – plan review, design, construction…
• My favorite tools: Groundcover, Big Holes, and Big Berms
• Happy to share and be in the role of teacher today
• But the reality, I will forever be a student in the EC cycle
What’s in it for me/Takeaways?
• Designers – include transitional items on the plan
• Contractors – rely on the tools in your toolbelt, assess, and change as needed
• Developers – Save money by learning to pay now and not 3 times as much later
• Regulators – toolbelt review, reminder of our important roles
• 3rd Party Inspector – toolbelt review, reminder of your important role
• Neighbors – Less potential for offsite sediment on your properties
Today’s Journey:
• E&SC Fundamentals/Building Blocks• Erosion Control vs Sediment Control
• Discuss a few tools in your E&SC Toolbelt• Practice• What to do onsite if problem exceeds what your toolbelt can handle
Plan, Construction,andInspection Considerations
Basic Control Objectives:
1)Identify Critical Areas – Identify areas subject to erosion & offsite areas vulnerable to erosion and sedimentation
2) Limit Exposed Areas – Limit the size of the area to be exposed at any one time
3) Limit Time of Exposure – Limit exposure to shortest time
4) Control Surface Water – Control upstream surface water to reduce erosion and sediment loss during exposure
5) Control Sedimentation/Manage Stormwater Runoff –land disturbances planned to prevent offsite-sedimentation
Not all measures treat the same particle size
• Silt fence - Mostly Sands• Basins/Traps – Fines
• PONDING = Best Treatment for fines
Erosion Control vs. Sediment Control• Erosion Control
• Primary focus is on “prevention”
• Goal: to hold in place and “not to chase” soil particles
• Very effective, Looks good
• Sediment Control• Primary defense in mass grading
with large bare areas• Goal: to capture sediment after
soil detachment• Low/Medium effectiveness,
Doesn’t always look good
Tool #1 – Triple Threat Treatment for slopes
• Berms, Slope Drains, and groundcover are the primary E&SC devices:• 1) Control Upstream surface
water through use of diversions/berms
• 2) Slope drains to convey runoff from upstream area to the toe of the slope
• 3) Groundcover, Groundcover, Groundcover!!!! (Preferably vegetative)
Tool #2 – Excavated Storage/Hole
• Check dam w/ weir and temporary sediment traps are the primary E&SC devices:1) Place in front of silt fence and outlets2) Utilize in Ditches upstream of check dams3) Utilize on upstream side of slope drains4) Utilize on downstream side of pipes w/ dissipator padThis tool can decrease repair frequency, provide more treatment of smaller particles, slow runoff, etc.
Tool #3 – Berms/Diversions
• Temporary Diversions/Berms, are the primary E&SC devices:1) Top of slopes >8-10ft
2) Route bare areas to basins/traps, excavated storage areas
3) Route runoff to Storm drain inlets
4) Route extra drainage area to basin
Tool #4 – Stream Crossings: If adequate sediment storage is not provided onsite, our
streams will become our sediment basins!
• 2/4 Corner Basins/Traps fed by diversions/berms provide E&SC upstream of Crossing:1) “Construction in the Dry” and Stream Bypass2) Stable stone approaches at least 50 ft on both sides3) Temporary Equipment Xing: timber/composite mat, stone?, or piped (incl. detail)4) Timber Mat Crossings – No gap between boards, geotextile underlayment, and provide side protection5) RECP on slopes6) Install in dry weather pattern7) More measures needed if install exceeds 1 day
2/4 Corner Basins/Traps
- Engineers: Please include 2 or 4 basins/traps with runoff conveyance on plans prior to submitting.
- Developers: If these measures aren’t on your plans, request them
- What happens when inadequate sediment storage and runoff conveyance are missing? OUR STREAMS BECOME OUR SEDIMENT BASINS!!!
What’s Missing from this Phase 1 E&SC Plan? Red = Stream CrossingBlue = Stream CrossingGreen = Stream Crossing
What’s Missing from this Phase 1 E&SC Plan?
Timber Mat Xing
Pipe Xing
Repeat for 3rd Xing
Excavated storage area w/ berms
Excavated Storage in DitchCourtesy of NCDOT
Tool #5 – Groundcover
• Temporary and Permanent Groundcover Choices:1) Rolled Erosion Control
Product (RECP)2) Vegetation3) Anchored Straw Mulch4) Single Shredded Coarse
Ground Wood Mulch5) Asphalt6) Concrete7) Soil Cement8) Geotextile/Tarps/Plastic
Sheathing9) Stone
Single Shredded Coarse Ground Mulch
• Drought tolerant groundcover
• Wet tolerant groundcover
• Easy application• Slopes and flat areas• Re-usable• Residential,
commercial, industrial, linear, and solar sites!
Tool #1 – Triple Threat Treatment
Tool #2 – Excavated Storage/Hole
Tool #3 – Stream Crossings
Tool #4 – Berms & Diversions
Tool #5 - Groundcover
Remember the Tools that we Sharpened in our Toolbelt Today
Goal – Keep Our Soil on our Site
It’s Time to
Contact Someone
Else:
• Designer/Consultant • Site Inspector/Regulator• 3rd Party Consultant• Developer• Contractor
Questions?
• Karyn Pageau, EI, CPESC• Environmental Consultant • Wake County• [email protected]• 919-796-8769