Client: Polk Center, Venango County, PA
Year Completed: 2009
Project Cost: $1,000,000
Gwin, Dobson & Foreman, Inc. was selected by the Commonwealth of Pennsylvania to design the breaching of Piffer Dam and the replacement of Lake Saguin. Because of overtopping during a May 2006 flood and its overall poor condition, the Commonwealth elected to remove the dam. The former impoundment (Lake Saguin) was replaced with a 1.9 million gallon pond to provide institutional fire protection. Constructed in two phases, the project included the following work elements:
- Piffer Dam was an earthen dam, 377-feet long and 26 feet high. Classified as a “high hazard”” dam by DEP Division of Dam Safety, the 8-acre reservoir had a capacity of 19 million gallons.
- Breaching of 110-year old Piffer Dam (Phase I) with earthwork excavation, channel stabilization, storm sewer extension, rock lining of the breach area, spillway demolition, sedimentation control and water management. The breach opening was hydraulically sized for the “probable maximum flood” condition.
- Waterline relocations including a 12-inch transmission main near the dam embankment and a 12-inch line through the reservoir area.
- Sanitary sewer relocations including a 12-inch sewer along the south dam abutment and a 110-foot long, 36-inch deep wide-flange beam over the breach opening to support an existing 10-inch gravity sewer (with expansion system, interconnection and pipe insulation). See photo.
- Earthwork excavation and embankment for the new 1.9 million gallon pond construction with geosynthetic clay liner and rock lining.
- Sandy Lick Creek intake structure including reinforced concrete intake, screens, outlet works, 12-inch pond fill line, channel modification, stream diversion and appurtenances.
- Installation of “dry” hydrants and suction lines to the pond.
The project was completed within the Department’s budget. GD&F performed all professional services including design, plans/specifications, cost estimates, permit applications and construction phase support. Engineering work included hydrology/hydraulic design of the dam breach and institutional fire flows and durations for required pond storage.