National Dam Inspection Program. Pioneer Lake Dam (NDI ID Number PA-431, DER ID Number 32-80), Susquehanna River Basin, Offstream, Hazelet Run, Indiana County, Pennsylvania. Phase I Inspection Report

Abstract

Abstract : The assessment of Pioneer Lake Dam is based upon visual observations made at the time of inspection, review of available records and data, hydraulic and hydrologic computations and past operational performance. The dam and appurtenant structures appear to be in fair condition. No major erosion was observed on the embankment crest. An erosion area was observed at the outlet for the 12 in. diameter cast iron pipe. Erosion at the outlet of the 12 in. diameter pipe exists on the downstream slope of the dam near the toe. Seepage 100 ft. right of the spillway channel was measured to be approximately 50 gallons per minute. A 30 in. corrugated metal pipe exists beneath the roadway near the outlet for the emergency spillway. It was observed during the inspection that the pipe is collapsing near the center of the pipe. Trees were observed growing along the upstream edge of the crest, and dense vegetation was observed along the entire length of the downstream slope. The Pioneer Lake Dam is a high hazard-small size dam. The recommended spillway design flood (SDF) for a dam of this size and classification is in the range of the 1/2 PMF to PMF. Due to the downstream potential for loss of life and property damage, the spillway design flood has been selected as the PMF. The spillway and reservoir are capable of controlling approximately 11% of the PMF without overtopping the embankment. Based on criteria established by the Corps of Engineers, the spillway is termed seriously inadequate. Pioneer Lake Dam is classified as unsafe, non-emergency.