Stream Stabilization for Emergency Sewer Breaks in Fairfax County

Edward Umbrell, PE, Rosgen Level IV, Senior Project Manager, Dewberry Engineers Inc

Joshua Abreu, EIT, Staff Engineer, Dewberry Engineers Inc


Stream Stabilization for Emergency Sewer Repairs in Fairfax County

Edward Umbrell, PE, Dewberry 

Joshua Abreu, EIT, Dewberry  

Historically, stream valleys are prime real estate for sanitary sewer systems due to their low elevation and natural drainage capability.  Fairfax County (County) has thousands of sewer segments that are in and around these urban stream corridors.  Since their original installation over 40 years ago, streams have eroded and sewer lines have become exposed, posing risk of failure.  Over the past several years, the County has responded to numerous locations of exposed sewers to perform emergency protection and replacements.  Recently, the County has developed a holistic approach to assess, repair and/or replace these exposed sewer lines in their urban stream corridors.  As part of the repair effort, the eroded streams in the vicinity of the exposed sewer lines have had to be stabilized using a variety of stream restoration techniques.

This presentation will include the following “Lessons Learned”

  1. Assessment procedure and risk
  2. Immediate actions (sewer bypassing, access, coordination)
  3. Field Survey
  4. Environmental Permitting
    1. Wetland delineation
    2. Tree preservation
  5. E&S Plans
    1. Clean water bypass
    2. Site access & staging
  6. Sewer Repair
    1. Geotechnical considerations
  7. Stream Bank Grading
  8. Stream Bank Armoring
  9. Instream Structures
  10. Stream and Riparian Vegetation
  11. Floodplain Evaluation
  12. Construction Administration & Monitoring
    1. Specialty Stream Restoration Contractor
    2. Safety
    3. Stream Valley Trails & Pedestrians
  13. Community Relations
    1. Sound Attenuation

Author Bio

Edward Umbrell is a professional engineer and project manager in Dewberry's Gainesville, VA office. He has extensive experience in water resources, stream restoration, natural channel design, storm outfall retrofits, stormwater management facility design, best management practices (BMPs), MS4 permitting, floodplain studies, and land development. His experience in stream restoration and stormwater design, along with his familiarity in all aspects of land development including design, approval, permitting, construction administration and surveying makes him uniquely qualified as an expert in water resources and land development engineering.

Joshua Abreu is a staff engineer with experience in water resources which includes the design of stormwater management facilities, performing surface hydrologic and hydraulic analysis, preparing dam break and floodplain studies, site plan preparation, and inspection of stormwater management facilities.