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January 29, 2015 Building Design Branch Huntington Levee Community Meeting
| Date post: | 15-Jul-2015 |
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January 29, 2015
Building Design Branch
Huntington Levee Community Meeting
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
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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
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Project Background
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
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Project Background
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
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Project Background
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
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Building Design Branch
Interior Drainage Analysis
Interior Levee Exterior
Note: Exterior (Cameron Run) Modeling Completed July 2014
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
Building Design Branch 9
Existing 100-year Water Surface Elevation
Interior Drainage Analysis
Building Design Branch
Interior Drainage Analysis
Building Design Branch
Interior Drainage Analysis
HEC-HMS Modeling Approach
Building Design Branch
Interior Drainage Analysis
HEC-HMS Results – Hypothetical EventsClosed 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
Building Design Branch
Interior Drainage Analysis
Project Cross-Section Key Elevations
Building Design Branch 14
100-year stormwater ponding at elevation 8.0’
Interior Drainage Analysis
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
Building Design Branch
Interior Drainage Analysis
Historical Flood Events - Cameron Run – Jones Point Rainfall
Peak Water Surface Elevation based on HEC-HMS modelling
Building Design Branch 17
25-year stormwater ponding
Interior Drainage Analysis
Building Design Branch 18
10-year stormwater ponding
Interior Drainage Analysis
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
Building Design Branch 20
Levee impact and storage requirements
Interior Drainage Analysis
Building Design Branch 21
Pump Station
Building Design Branch 22
Pump Station
Pump Station Equipment
• 3 Active Stormwater Pumps
• 1 Backup Stormwater Pump
• 2 Dewatering Pumps
• Generator for Emergency Power
Building Design Branch 23
Preliminary Interior Rendering
Pump Station
Building Design Branch 24
Scaled Model of PumpingConfiguration
Pump Station
Building Design Branch 25
Preliminary Exterior Rendering
Pump Station
Building Design Branch 26
Preliminary Exterior Rendering
Pump Station
Building Design Branch 27
Construction and Maintenance Access
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
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Schedule
Schedule
Building Design Branch
• Next Steps
• Site Permit Submission – February 2015
• Pump Station Work Session – February 2015
• Design Development Submission (60%) – April 2015
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Schedule
Schedule
Building Design Branch
Schedule
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Building Design Branch
Community Outreach
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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
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Building Design Branch
Community Outreach
• Bi-annually
• Important Milestones
• Next Community meeting – July 2015
• Updates on Permitting
• Interior Ponding Development
• Pump Station
Community Meetings
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Building Design Branch
Questions
Contact Information – Huntington Levee Project Phone #: 703-324-5800
Email address: [email protected]
Contact Information – Stormwater Questions Phone #: 703-324-5821
Email address: [email protected]
Huntington Levee Website: www.fairfaxcounty.gov/dpwes/huntingtonlevee
To request this document in an alternate format call 703-324-5800, TTY 711.
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