National Dam Inspection Program. Big Brown Dam. Susquehanna River Basin, Browns Run, Cambria County Pennsylvania (NDI I.D. Number PA-00502, DER I.D. Number 11-1). Phase I Inspection Report

摘要

Big Brown Dam consists of an earth embankment approximately 290 feet long with a maximum height of approximately 37 feet from the downstream toe, and a crest width in the range of 8 to 11 feet. The downstream slope of the dam is 1-1/2 horizontal to 1 vertical and is protected with well-established grass. The upstream slope is protected by riprap extending to the crest level of the dam. The flood discharge facilities for the dam consist of a primary spillway incorporated into the outlet facilities and an open channel emergency spillway located on the right abutment. The outlet facilities consist of a 20-inch cast-iron supply line and a 20-inch cast-iron blow-off pipe. Based on the evaluation of the existing conditions, the condition of Big Brown Dam is considered to be poor. Extensive swampy areas were observed along the toe of the dam. This condition, together with the steep downstream slope of the embankment raises concern as to the continued stability of the embankment. The flood discharge capacity of the dam was found to be at the lower limit of the recommended spillway capacity range of 50 percent to full PMF relative to the size and hazard classification of the dam.