SILVER LAKE DAM - MIDDLETOWN - DE00051-3531

Incident ID DE00051-3531
Dam Name SILVER LAKE DAM - MIDDLETOWN
Downstream Hazard Potential H
State DE
Incident Date 07/27/2022
Incident Type Non-failure
Incident Driver Seepage/internal Erosion
Incident Mechanism 1 Piping
Incident Mechanism 2 Sinkhole
Incident Mechanism 3 Excessive/increased Seepage
Incident Description On 7/27/2022 a sinkhole was discovered on the upstream slope adjacent to the right winwall of 1 of the bridge/spillway structures (this dam has two bridges with gates on the upstream side and a smaller culvert with boards on the upstream side) with an active boil on the downstream side of the dam. The piping/voids were under the bridge slab. The road was closed, the pond level was lowered and immeadiate measures including a liner and large sand sacks were placed on the upstream seepage entry point to prevent progression. Permanent repairs included flowable fill to fill the sinkhole and holes were drilled thru the slab to inject flowable fill in the voids under the bridge slab. All trees were clearded along the upstream slope and a sheet pile cutoff and riprap were installed.
Named Hydrologic Event
EAP Enacted (Y/N) due to Incident Yes
Fatalities (Number)
Number of People Evacuated 0
Number of Habitable Structures Evacuated 0
Number of Habitable Structures Flooded 0
Other Infrastructure Impacts Bridges
Economic Damages (in $) $1 million to $5 million
Volume released at failure (ac-ft)
Response
Additional Remarks or Updates
Incident Time
Incident Duration
Incident Report Produced No
Information Sources DE Dam Safety
Owner Type S
Dam Type PGRE
Primary Purpose(s) R
EAP Y
Year Completed 1945
Year Modified 0
Dam Height 18 ft
Max Storage (ac-ft) 591 ac-ft
Surface Area (acres) 39 acres
River Name DEEP CREEK
Latitude 39.438
Longitude -75.6934
Regulatory Agency(ies) DNREC
NID Number DE00051
Attachments