Dam Safety

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Common Problems at Dams - Leakage in Principal Spillway

Probable Causes and Possible Consequences

Recommended Actions

  • Natural weathering will cause deterioration of poor quality concrete and corrosion of metals.
  • Poorly designed outlet conduits and structures will crack or fail when subjected to excessive pressures and forces.
  • Water can infiltrate cracks leading to corrosion of reinforcing steel and breakdown of concrete during freeze-thaw cycles.
  • Deterioration of outlet conduits and structures can lead to costly repairs, inadequate spillway capacity, leakage, and erosion of the dam.
  • Leakage is a serious sign of deterioration of outlet conduits and structures.
  • Leaks can develop through poorly sealed joints in pipes and concrete structures.
  • Water Leaking into or out of conduits will erode the dam, eventually leading to dam failure.
  • Small cracks in concrete structures should be sealed with a quality polyurethane caulk.
  • Maintain protective galvanization, paints and coatings on metal structures and reinforcing steel.
  • Apply concrete sealers or topcoats to protect slightly weathered concrete.
  • Slipline corroded corrugated metal pipes with pressuretight plastic pipe that is grouted in place or line the pipe with cast-in-place pipe.
  • Severely deteriorated outlet conduits and structures should be evaluated by a qualified engineer to determine the best course of action.
  • Poorly sealed joints in conduits should be sealed with expandable rubber gaskets or by injecting hydrophobic urethane sealant.
  • Severely deteriorated structures should be evaluated by a qualified engineer to determine the best course of action.
  • Corroded corrugated metal pipes with holes should be replaced. Plans for replacement must be prepared by a qualified engineer and submitted to NeDNR for approval.


coroded pipe

Corrosion of the corrugated metal principal spillway pipe led to this dam failure in Adams County.


HDPE pipe that is ready to be sliplined with pressure-tight, solid-wall in a pipe that is close to corrosion

Rusty corrugated metal pipes can be sliplined with pressure-tight, solid-wall, HDPE pipe that is grouted in place. (Photo source: FEMA)

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