BLAIRS POND DAM - DE00070-1205
Dam Name: BLAIRS POND DAM
State: DE
Downstream Hazard Potential: H
Incident Type: Non-Failure
Incident Date: 08/28/2011
Incident Driver: Hydrologic/Flooding
Incident Mechanism 1: Erosion
Incident Mechanism 2
Incident Mechanism 3
Incident IDDE00070-1205
Incident DescriptionProlonged discharge at a higher than normal rate through a concrete overflow spillway exacerbated erosion of a known void in the soil beneath the spillway.
Named Hydrologic EventIrene
EAP Enacted (Y/N) due to IncidentNo
Fatalities (Number)
Number of People Evacuated0
Number of Habitable Structures Evacuated
Number of Habitable Structures Flooded0
Other Infrastructure Impacts
Economic Damages (in $)None
Response
Volume released at failure (ac-ft)0
Additional Remarks or UpdatesVoid was discovered under the left downstream edge of the spillway during an inspection in August 2011, and had not been repaired prior to Irene. The immediate post-Irene inspection did not reveal any change in the size of the void, but 11 days after the storm a sinkhole developed near the left upstream corner of the spillway. The remaining flashboards were removed from the spillway to lower the pond level below the spillway elevation and the void was filled with concrete on 9/9/2011. Subsequent repairs will be made to seal open construction joints and cracks in the spillway slab, which are thought to be the source of leakage through the slab that caused the void to develop.
Owner TypeS
Dam TypeREPG
Primary Purpose(s)RF
EAPN
Dam Height15 ft
Max Storage (ac-ft)611.00
Surface Area (acres)48.00
Year Completed
NID NumberDE00070
River NameBEAVERDAM BRANCH
Latitude38.904
Longitude-75.4848
Year Modified
Regulatory Agency(ies)DNREC
Incident Time
Incident Duration
Incident Report Produced
Information Sources
