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

E&SC Fundamental Reminders

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

Erosion Process – Which are we dealing with?

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

It’s Tool Time

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)

Photo courtesy of NCDEMLR

Triple Threat Treatment on Slopes: Berm, Slope Drain, and Groundcover

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.

Area downstream of culvert still has leaf/straw litter after 2” storm event

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

What about on asphalt?

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

Stream Diversion & “Construction in the dry”

Courtesy of DEMLR

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!

Groundcover

More Groundcover

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

Let’s Practice: Which tool(s) would you use?

When the problem exceeds your toolbelt…

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• karyn.pageau@wakegov.com• 919-796-8769