Minnesota Department of Transportation

511 Travel Info

Bridges and Structures

Design, construction and maintenance resources

Do It Right! Lessons from the field not to be repeated


  • Structures are to be backfilled with clean sand, not oversize rocks, bricks and construction debris.
  • A one-foot maximum lift is allowed when using a vibratory roller . . . but here, only a plate tamper is available, so they will need
    compact and water every 6” lift.
  • Backfill with sand, not steel
    plates and bituminous chunks!
  • The Contractor should fill the bug
    holes before backfilling . . . and make sure to clean the dried concrete off the rebar prior to pouring the end block.
  • How will they ever get density
    behind this abutment now?
  • More debris in backfill . . .
  • Ripples in waterproofing, burying lumber, rebar and concrete rubble in the fill.
  • Is there fabric on the conduit? Don’t damage the drainage system while backfilling the wall!
  • When backfilling structures, make sure to use only clean sand. Sod, protection fencing and other debris are not allowed.
  • Make sure the drainage system is protected from damage when backfilling any structure, but be especially careful when backfilling retaining walls with weep holes.
  • This pipe can be sheared off and lead to big problems.
  • Before backfilling abutments or retaining walls, make sure that surface cavities are filled and waterproofing has been installed
  • Backfill using clean sand, not garbage and concrete.
  • Make sure waterproofing stays in
    place during backfilling operations.
  • Don’t permit material in backfill
    that might damage waterproofing.
  • When backfilling retaining walls with
    daylight drains, make sure the drainage system stays intact.
  • All the money spent on all the
    aesthetic treatment in this corridor, only to end up with this mess...