Description: The stream scoping application is used by county staff to determine if a stream is in need of restoration. Staff visit selected sites and input stream data into the app. Data collected in this manner helps prioritize future stormwater management improvement projects.

1. A Fairfax County, VA, publication
Department of Public Works and Environmental Services
Working for You!
Stream Scoping Application Overview
February 2018

2. The Technology…
• Application Map
2Stormwater Planning Division
Project Scoping Application

3. The Technology…
• Select Scoping Site (red star)
3Stormwater Planning Division
Project Scoping Application

4. The Technology…
• Edit Scoping Site
4Stormwater Planning Division
Project Scoping Application

5. Project Scoping Application
“Field Form” – Site Overview Information (red stars)
5Stormwater Planning Division
• Project Name, ID, Drainage
Area, and % Impervious are
pre-filled and do not need to
be changed
• Field staff to complete
Scoping Team with member
names, date and weather

6. Project Scoping Application
• Access, Utilities, Ownership,
and Stream Order are pre-
filled
• These fields need to be
confirmed by the staff in the
field
– If limits of site change,
easement and ownership may
also change
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“Field Form” – Planning Score (red star)
Stormwater Planning Division

7. Project Scoping Application
“Field Form” – Planning Score (red star)
7Stormwater Planning Division

8. Project Scoping Application
“Field Form” – Channel Dimensions
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• New reach examples:
– Change in channel dimensions
– Change in vegetative buffer
– Tributary confluence
– Road crossing
• Reaches are drawn in the
application and appear in
blue
Stormwater Planning Division
Image courtesy of Indiana Fluvial
Erosion Hazard Program

9. Project Scoping Application
“Field Form” – Channel Dimensions
9
• A, W, and D from the
Urban NC Regional Curve
are pre-loaded in the site
data
• Note this is based on the
DA at the pour point of
the site
Stormwater Planning Division
1
10
100
0.01 0.10 1.00 10.00
Cross-SectionalArea(sqft)
Drainage Area (sq mi)
Published Regional Curves for the
Piedmont Physiographic Region
NC Urban
(41% I.A.)
Graph
courtesy of
North
Carolina State
University
Cooperative
Extension

10. Project Scoping Application
“Field Form” – Channel Dimensions
10Stormwater Planning Division
• Pull down:
– I – Stable
– II – Incision
– III – Widening
– IV – Aggradation
– V – Quasi Stable

11. Project Scoping Application
Stormwater Planning Division
“Field Form” – Reach Comments
11
• Bridges:
– Note number, type and
condition
– Drop a purple square
“Scoping Issue”
• Outfall:
– Note number, condition
(good, fair, poor) and if
work is needed
– May be a note in Stormnet
Issues
• Safety Issues:
– May include infrastructure
loss
– Note key attributes
(distance from top of
bank)
– Drop a purple square
“Scoping Issue”

12. Project Scoping Application
Stormwater Planning Division
“Field Form” – Reach Comments
12
• Buffer – Left and Right:
– Input in feet
• Human Impact
– May include trails,
infrastructure, mowing,
clearing, dumping,
stabilization projects

13. Project Scoping Application
“Field Form” – Reach – Instability Score
• Based on BEHI (Bank Erosion
Hazard Index) and Pfankuch
Stability Index
• Comprised of:
– Four parameters:
• Streambank vegetation
• Bank slope
• Mass wasting
• Cutting of banks and bed
– Adjustment points
• Excessive aggradation
• Excessive scour to bedrock
13Stormwater Planning Division
Image courtesy of Rosgen

14. Project Scoping Application
“Field Form” – Instability Score - Vegetation
• Immediate area at top of
bank
• Rooting depth and
density
• Think about the ability of
roots to hold the banks
• This is NOT the condition
of the buffer or buffer
width
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15. Project Scoping Application
“Field Form” – Instability Score - Vegetation
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16. 16
Project Scoping Application
“Field Form” – Instability Score – Bank Slope
Stormwater Planning Division

17. Project Scoping Application
“Field Form” – Instability Score – Mass Wasting
• Mass wasting = slope failure
• Downslope movement of
soil/rock typically as a mass,
largely under the force of
gravity but frequently
affected by water
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18. Project Scoping Application
“Field Form” – Instability Score – Cutting
• Lateral migration and incision
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19. Project Scoping Application
“Field Form” – Instability Score – Cutting
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20. Project Scoping Application
“Field Form” – Instability Score – Team Score
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21. Project Scoping Application
“Field Form” – Instability Score – Adjustment Points
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22. Project Scoping Application
“Field Form” – Scoping Issues (purple squares)
• Headcuts
• Bridges
• Failed/threatened
infrastructure
• Exposed utilities
• Dumpsites
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23. Project Scoping Application
“Field Form” – Restoration Opportunity
23Stormwater Planning Division
• Priority Level 1
– New stable channel
– Use existing floodplain (raise
channel bed)
– Raises water table elevation
• Priority Level 2
– New stable channel
– Excavates new larger floodplain
(removing legacy sediments
– Significant impact to trees
• Priority Level 3
– Restore existing channel
– Excavate new (narrower)
floodplain or bench
• Priority Level 4
– Stabilize in place using armoring
techniques

24. Additional Information
For additional information, please contact
Project Scoping Application
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703.324.5500, TTY 711
Stormwater Planning Division
Irene Haske
www.fairfaxcounty.gov/publicworks