The document summarizes a community meeting about the design of the Huntington Levee project. It discusses the project background and completed tasks like surveys and conceptual design. It also describes the interior drainage analysis that was conducted to understand water flow behind the levee and size pumps and storage areas. Upcoming steps include permit submissions and a pump station design session. The schedule forecasts completing design in 2017 and construction from 2017-2019. Future community outreach plans are also outlined.

1. January 29, 2015
Building Design Branch
Huntington Levee
Community Meeting

2. Building Design Branch
Agenda
I. Project Background & Completed Tasks
II. Interior Drainage Analysis
III. Pump Station Design
IV. Construction Access
V. Schedule and Next Steps
VI. Community Outreach
VII. Questions
2

3. Building Design Branch
• June 2006 -160 homes
were flooded from a storm
event
• 2009 – US Army Corps of
Engineers (USACE)
completed a study to
evaluate flood damage
reduction measures in the
Huntington Community
3
Project Background

4. Building Design Branch
• November 6, 2012 – Fairfax County voters approved stormwater
bond referendum to fund design and construction of flood damage
reduction measures proposed by the USACE
• June 2013 – Fairfax County awarded the levee design contract to
ARCADIS
• November 2013 – ARCADIS submitted the Phase I design package to
Fairfax County
• Survey, Geotechnical Investigation, Wetland Delineation, and
Conceptual Design
• January 2014 – Fairfax County and Huntington Community reach
consensus on conceptual design features
4
Project Background

5. Building Design Branch
• July 2014 – ARCADIS completed Hydraulic and Hydrologic Modelling
for Cameron Run
• September 2014 – ARCADIS submitted Schematic (30%) Design
package to Fairfax County
• October 2014 - Fairfax County conducted Value Engineering
Workshop
• December 2014 – ARCADIS began Design Development (60%) phase
• December 2014 – Geotechnical Report submitted for Permitting
• January 2015 – ARCADIS completed the Interior Drainage Analysis
5
Project Background

6. Building Design Branch
Project Background
• Earthen Levee/I-Wall Combination
• Collection Drains
• Pump Station Location – East end of levee
• Stormwater Diversion – Concrete box culverts
Key Design Features
6

7. Building Design Branch
Interior Drainage Analysis
Interior Levee Exterior
Note: Exterior (Cameron Run) Modeling Completed July 2014

8. Building Design Branch
Interior Drainage Analysis
Purpose
• Understand how water flows on land behind levee
• Understand how adding the levee will change the water flow
• Set design water elevation
• Size pumps and interior water storage area
• Provides the data necessary for the FEMA Accreditation
package and revision to the Floodplain Maps.
• Support the Floodplain Study for submission to the County
Land Development Services

9. Building Design Branch 9
Existing 100-year Water Surface Elevation
Interior Drainage Analysis

10. Building Design Branch
Interior Drainage Analysis

11. Building Design Branch
Interior Drainage Analysis
HEC-HMS Modeling Approach

12. Building Design Branch
Interior Drainage Analysis
HEC-HMS Results – Hypothetical Events
Closed Drainage Structures
Peak Pond Elevation based on HEC-HMS modelling
Storm Intensity Rainfall Depth (in.) Peak Pond Elevation
(ft.)
2- year 3.17 5.5
5- year 4.07 6.1
10- year 4.87 6.6
25- year 6.09 7.1
50- year 7.18 7.5
100- year 8.41 8.0
500- year 12.00 9.1

13. Building Design Branch
Interior Drainage Analysis
Project Cross-Section
Key Elevations

14. Building Design Branch 14
100-year stormwater ponding at elevation 8.0’
Interior Drainage Analysis

15. Building Design Branch
Interior Drainage Analysis
Historical Flood Events - Cameron Run – Jones Point Rainfall
Historical Event Rainfall at Jones
Point Station
(Inches)
Peak Water
Surface Elevation
(Feet)
July 28, 2000 1.12 4.1
September 23, 2003* 1.80 4.6
June 25, 2006 3.51 5.1
September 6, 2008 3.40 4.4
September 8, 2011** 2.64 4.5
June 10, 2013 2.30 4.6
June 28, 2013 1.59 4.4
July 12, 2013 2.46 4.8
May 16, 2014 2.68 4.5
Peak Water Surface Elevation based on HEC-HMS modelling
* Tropical Storm Isabel
** Tropical Storm Lee

16. Building Design Branch
Interior Drainage Analysis
Historical Flood Events - Cameron Run – Jones Point Rainfall
Peak Water Surface Elevation based on HEC-HMS modelling

17. Building Design Branch 17
25-year stormwater ponding
Interior Drainage Analysis

18. Building Design Branch 18
10-year stormwater ponding
Interior Drainage Analysis

19. Building Design Branch
Interior Drainage Analysis
Interior Ponding Area
• Provides location for stormwater until it can be pumped out
• Controlled flooding area
• Coordinating with Fairfax County Park Authority on design
and possible amenities
• Likely not athletic fields

20. Building Design Branch 20
Levee impact and storage requirements
Interior Drainage Analysis

21. Building Design Branch 21
Pump Station

22. Building Design Branch 22
Pump Station
Pump Station Equipment
• 3 Active Stormwater Pumps
• 1 Backup Stormwater Pump
• 2 Dewatering Pumps
• Generator for Emergency Power

23. Building Design Branch 23
Preliminary Interior Rendering
Pump Station

24. Building Design Branch 24
Scaled Model of Pumping
Configuration
Pump Station

25. Building Design Branch 25
Preliminary Exterior Rendering
Pump Station

26. Building Design Branch 26
Preliminary Exterior Rendering
Pump Station

27. Building Design Branch 27
Construction and Maintenance Access

28. Building Design Branch
• Phase II (January 2014-Winter 2017)
• Schematic Design (30%)
• Design Development (60%)
• Permitting
• Land Acquisition
• Construction Documents (100%)
• Bidding
• Phase III (Winter 2017-Spring 2019)
• Construction
28
Schedule
Schedule

29. Building Design Branch
• Next Steps
• Site Permit Submission – February 2015
• Pump Station Work Session – February 2015
• Design Development Submission (60%) – April 2015
29
Schedule
Schedule

30. Building Design Branch
Schedule
30

31. Building Design Branch
Community Outreach
31

32. Building Design Branch
Community Outreach
• Community Meeting notes will be placed on the web site 2
weeks after the meeting
• Quarterly emails sent out to the project listserv with progress
made in the past three months and what to expect in the next
three months
• Schedule – added a feature to the web site to help the
Community track the progress of the active components of the
project.
Communication
32

33. Building Design Branch
Community Outreach
• Bi-annually
• Important Milestones
• Next Community meeting – July 2015
• Updates on Permitting
• Interior Ponding Development
• Pump Station
Community Meetings
33

34. Building Design Branch
Questions
 Contact Information – Huntington Levee Project
 Phone #: 703-324-5800
 Email address: HuntingtonLevee@fairfaxcounty.gov
 Contact Information – Stormwater Questions
 Phone #: 703-324-5821
 Email address: SWPDmail@fairfaxcounty.gov
 Huntington Levee Website:
www.fairfaxcounty.gov/dpwes/huntingtonlevee
To request this document in an alternate format call 703-324-5800, TTY 711.
34