Rush Creek: A Story of Redemption

Arlington Stormwater Division  Stormwater Division of Public Works is:  Engineers  Education  Environmental Compliance Officers  Operations and Maintenance  Stormwater Utility Fee  Based on impervious area  Funding raised from $1.30 in 2007 to $4.25 in 2010 ($3.8 million a year to $10.3)

Arlington Stormwater Background  Arlington Policy History  Rational Method Design  5-25 year storm sewer design  Detention only required if “downstream” structural flooding occurs  BMPs recently required based on site size  Erosion control projects only when infrastructure is threatened  Past Drainage Projects  Drainage projects were limited scope and highly localized  Buyout projects:  Johnson Creek area (140 structures in 2003)  Rush Creek – Shady Valley (6 structures in 2009)

Rush Creek Background  Rush Creek Watershed stats  ~28 square miles  ~260,000 linear feet of creek  ~1,500 structures in floodplain  Flooding history?

Rush Creek Development

September 8, 2010 – 50 Year Storm

Sept 8 th, 2010 Storm  Damage estimates  After the Storm  High water marks  Federal disaster declaration ???

Buyout Timeline  Decision timeline  Grants and federal uncertainty  Previous projects and conclusions  Letters, council executive sessions and waiting…  To wait or not to wait  COUNCIL APPROVAL and spontaneous impatience

Demo Timeline appraisal / offer closing internal permit Securit y and mowing testing gas and electric water service notify state habitattraining demo day pay people

Lessons Learned vegetation and restoration are costly unknown costs when testing is done coincidental to demo news of vacant houses travels fast make ownership as clear as possible, stop ANYONE on site make friends with your enemies (AKA unhappy residents) write a policy before you need it (lots of reasons against it come up after a flood) be annoying with coordination what SWPPP??? make sure all departments are speaking with “one voice”

What’s next  Park Plan  Public meetings  Other buyouts  Gauges  Watershed Study

Why bother with a watershed study  Regulation of development  Better CIP planning  Need accurate flood risk  Assessment of channel stability

Watershed Disorders  Watershed mixing  Development-friendly environment  Built-out  Large number of small tributaries  Unstable  Undersized bridges

 Unsteady Hec-RAS  2D Area  Hydrology  Sub- watershed boundaries  Channel stability analysis  Project Alternatives The Plan

City Project Manager (CDM-Smith) Hydrology Consultant (Halff Associates) Channel Stability (Michael Baker) Sub-Watershed Consultants RC-1 & Lower Rush (Dewberry) Middle Rush (AECOM) Upper Rush & Kee Branch (Michael Baker) The Structure

Project Schedule Project Kickoff with PMC July 2011 Hydrology Kickoff Nov 2011 Sub-Watershed Consultants Kickoff Jan 2012 Public Meeting Feb 2012 Survey Complete April 2012 Models Complete Oct 2012 Channel Stability Analysis Complete Oct 2012 Project Alternatives Complete Nov 2012 Submit Physical Map Revision to FEMA March 2013

Minor Details  Public meeting  Technical Standards  Website  Memos etc.  Survey  Coordination

Hydrology  Almost 300 sub-basins ranging from 5 acres to 163 acres  Submitting to FEMA in July  Example Discussion: Ultimate development assumptions  Assumed 75% impervious for all vacant land  Time of concentration

Fun Example

Questions