The document summarizes stormwater management activities and projects in Fairfax County. It discusses regulatory drivers for stormwater management including permits and TMDLs. It provides data on inspections and maintenance of stormwater infrastructure. Examples are given of completed stream restoration, outfall improvement, and low impact development projects. Budget information is presented showing funding sources for operations and capital costs.

1. January 21, 2015

2. Stormwater Drivers
• MS4 Permit
• Bay TMDL
• Other Local TMDLs
• Maintenance of existing facilities
• Public Safety /Emergency Response
• Dam Regulations

3. • Conveyance Systems
• Dam Safety and Facility
Rehabilitation
• Emergency and Flood
Response
• Operations
• Stormwater
Regulatory Program
• Streams and Water
Quality

4. • Inspect and maintain
approximately 1,500 miles of
storm sewer
• Investigate storm drainage
and flooding complaints
• Maintain inventory of
county facilities
Pipe Before Lining
Pipe After Lining
2013:
• Inspected 255 miles of pipe and
12,000 structures
• Relined/repaired over 19,000 LF
of storm sewer

5. • Dam certification and
regulatory compliance
• Dam inspection and
maintenance
• Dredging
2014:
• County SWM Facilities: 1749
• Inspected: 486
• Cleaned and mowed: 1,355
• Maintenance work orders: 3,432
• Private SWM Facilities: 3825
• Inspected: 744

6. Trends
6

7. • National Flood Insurance
Program
Community Rating
System (CRS)
• Storm monitoring
2013:
• Flood response events: 8
• Snow removal events: 20

8. • TMDL compliance
• MS4 permit
• 18 permit elements
• 16 Tactical Plans Complete
• 229 Action Items

9. • Wet and dry weather monitoring
• Annual stream bio-assessments (since 1999)
• Evaluate trends in stream
health countywide
2014:
• Dry Weather Monitoring:
• Screened: 102 outfalls
• 47 wet
• 0 required track down
• Benthic Macroinvertebrates:
• Sites Monitored: 70
• Fish Community:
• Sites Monitored: 23
• Bacteria Monitoring:
• Samples Taken: 176

10. Stream Quality Index

11. USGS Stream Gage Study
Evaluate long-term
trends in flow, nutrients
and sediment
2014:
• Streamflow data: 120,000
measurements
• Water Quality data: 96,000
measurements
• Monthly Grab Samples: 264
• Storm Event Samples: 136
• 42 manual streamflow
measurements made at the 20
sites to maintain streamflow
rating curve

12. •Rain Barrel Program
•Reforestation
•Community Outreach
& Public Education
•Stream clean-ups

13. • Stormwater Pond
Retrofits
• LID Implementation
• Outfall Improvement
• Stream restoration
• Area-Wide Drainage
Improvement
http://www.fairfaxcounty.gov/dpwes/stormwater/projects/project_list.htm

14. Completed Water Quality Projects
7
12
12
1
4
8
2
104
2
1
12
Completed Water Quality
Projects FY09-14
Number of Projects 83
Acres Treated 9,172
Linear Feet Treated 19,800
Phosphorous
Removed
1,262 lb/yr
Nitrogen Removed 3,591 lb/yr
Sediment Removed 277 tons/yr
2
3
1
1
1

15. Completed Facilities FY09-14
Cost Per Pound of Pollutant Removal
Practices Number
Installed TP TN TSS
Stream Restoration 21 $ 22,000 $ 20,000 $ 17
Infiltration Swales & Trenches 5 $ 24,000 $ 4,100 $ 146
Pond Retrofits 40 $ 37,700 $ 8,300 $ 192
Soil Compost Amendment 20 $ 108,000 $ 15,200 $ 700
Dry Swales 9 $ 120,700 $ 20,700 $ 732
Bioretention (Rain Gardens) 24 $ 52,400 $ 26,100 $ 925
Pervious Pavement 6 $ 190,300 $ 32,400 $ 1,200
Capital Cost($/lb/yr)

16. History of Stormwater Funding
$0.0
$5.0
$10.0
$15.0
$20.0
$25.0
$30.0
$35.0
$40.0
$45.0
$50.0
FY05 FY06 FY07 FY08 FY09 FY10 FY11 FY12 FY13 FY14 FY15
Operations (General Fund) Fringe (General Fund)
Public Works Construction (Fund 308) Operations (Fund 318)
Penny Dedication (Fund 318) Operations, Fringe & Contributory (Fund 125)
Stormwater Service District (Fund 125)

17. Stormwater FY15 Budget
(2%) NVSWCD, Occoquan Lab,
Towns, $1.0 M
(12%) Stormwater Regulatory
Programs, $5.5 M
(9%) Dam Saftey and Facility
Rehabilitation, $4.5M
(27%) Streams and Water
Quality, $13.2M
(10%) Conveyance Systems,
$5.0M
(38%) Operations, $18.1M
(2%) Emergency and Flood
Response, 0.9M
38% Operations
2% NVSWCD, Lab,
Towns
2% Emergency &
Flood Response

19. 19
Uncontrolled overland
flow leads to …
Flooding
Flooding Managed flow

20. Outfall Restoration
Loftridge- Before & After
Drainage Area
(acres)
Phosphorous Removal
(lbs/yr)
Nitrogen Removal
(lbs/yr)
Sediment Removal
(tons/yr)
34 11 13 3.8

21. Outfall Restoration
Loftridge- Now
Drainage Area
(acres)
Phosphorous Removal
(lbs/yr)
Nitrogen Removal
(lbs/yr)
Sediment Removal
(tons/yr)
34 11 13 3.8

22. Outfall Restoration
Sheffield Hunt– Before & After
Drainage Area
(acres)
Phosphorous Removal
(lbs/yr)
Nitrogen Removal
(lbs/yr)
Sediment Removal
(tons/yr)
29 64 188 25

23. Stream Restoration
Sheffield Hunt - Now

24. Stream Restoration
Bridal Path - Before & After
Drainage Area
(acres)
Phosphorous Removal
(lbs/yr)
Nitrogen Removal
(lbs/yr)
Sediment Removal
(tons/yr)
162 138 790 132

25. Stream Restoration
Dead Run – Before

26. Stream Restoration
Dead Run – During & After
Drainage Area
(acres)
Phosphorous Removal
(lbs/yr)
Nitrogen Removal
(lbs/yr)
Sediment Removal
(tons/yr)
415 15 283 2.5

27. Stream Restoration
Wolftrap Creek- Before & After
Drainage Area
(acres)
Phosphorous Removal
(lbs/yr)
Nitrogen Removal
(lbs/yr)
Sediment Removal
(tons/yr)
766 90 1,016 172

28. Fair Woods- Before & After
Area Treated
(acres)
Phosphorous Removal
(lbs/yr)
Nitrogen Removal
(lbs/yr)
Sediment Removal
(tons/yr)
26 9 44 0.9
Pond Retrofits

29. Fair Woods- Now
Area Treated
(acres)
Phosphorous Removal
(lbs/yr)
Nitrogen Removal
(lbs/yr)
Sediment Removal
(tons/yr)
26 9 44 0.9
Pond Retrofits

30. Low Impact Development
Spring Hill RECenter - After
Area Treated
(acres)
Phosphorous Removal
(lbs/yr)
Nitrogen Removal
(lbs/yr)
Sediment Removal
(tons/yr)
14 2.5 11.5 0.2

31. Kings Park West- Bioretention and Reforestation
Before
Drainage Area
(acres)
Phosphorous Removal
(lbs/yr)
Nitrogen Removal
(lbs/yr)
Sediment Removal
(tons/yr)
3 5 35 0.3
Low Impact Development

32. Kings Park West- Bioretention and Reforestation
now
Drainage Area
(acres)
Phosphorous Removal
(lbs/yr)
Nitrogen Removal
(lbs/yr)
Sediment Removal
(tons/yr)
3 5 35 0.3
Low Impact Development

33. Fred McMath Facility - Bioretention Before & After
Drainage Area
(acres)
Phosphorous Removal
(lbs/yr)
Nitrogen Removal
(lbs/yr)
Sediment Removal
(tons/yr)
1 1 9 0.1
Low Impact Development

34. Low Impact Development
Noman Cole WWTP- Before & After
Area Treated
(acres)
Phosphorous Removal
(lbs/yr)
Nitrogen Removal
(lbs/yr)
Sediment Removal
(tons/yr)
0.6 0.4 2

35. Questions?
Stormwater Planning Division 703-324-5500, TTY 711
www.fairfaxcounty.gov/dpwes/stormwater
www.fairfaxcounty.gov/dpwes/watersheds
SWPDmail@fairfaxcounty.gov
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