After more than 30 years of inspections and 10 years of talks between the Pennsylvania Department of Environmental Protection (PADEP) and Tamaqua officials, a full drainage and drawdown of the Upper Owl Creek Reservoir started Thursday morning and will take weeks or even months to completely empty into the Little Schuylkill River.
On Thursday morning, Tamaqua borough officials opened a valve that started the gravity-fed drainage of the reservoir into Owl Creek's dry lower reservoir bed, which empties into the Little Schuylkill River via a drop-box spillway. Following a PADEP inspection of all Pennsylvania dams in the 1970s, PADEP categorized both the upper and lower dams of Owl Creek reservoir as Hazard Category 1 (high) Size Class B structures, which state failure of the dam may result in probable loss of life and/or extensive property damage. This gave the Tamaqua Borough Council two options, to breach the dam permanently or redevelop it.
In 1883, the lower dam, the only dam at the time, was created to provide a water supply for Tamaqua and area residents. The lower dam was also reconstructed and raised six feet in 1928. Following size limitations and other factors, the upper Owl Creek Dam was constructed in 1921 to replace the older lower reservoir. In the late 90s, the Still Creek reservoir becoming Tamaqua's residential water supply, which resulted in the Owl Creek reservoir being sold back to the Tamaqua Borough.
Earlier this week, Tamaqua Borough and Water Authority workers performed a short test-run of the reservoir's drainage to inspect and prepare a drainage path on the west side of the Upper Owl Creek Dam in preparation for the constant water flow and drainage of the upper reservoir. PADEP's inspections, as well as recent inspections done via Benesch Engineering of Pottsville, showed many outlet works deficiencies and other factors that are in need of repair to keep the dam operating safely.
In October of 1999 and later meetings, the Tamaqua borough eventually opted for redevelopment of both dams for recreational use rather than permanently breaching the dam. In 2001, the dam was put on the PADEP's hit-list of dams that need destroyed or placed. In August of 2010, Schnabel Engineering of Pottsville, which used underwater cameras to inspect the dam and its pipes, released its Outlet Works Inspection Report of the Upper Owl Creek Dam they performed in May 2010.
The report included replacement or removal to the upper dam's concrete intake tower, control house, sluice gates, trash racks, pedestrian bridge, as well and many other required repairs. Based on the findings of the outlet inspection, a number of repairs were included in the final rehabilitation design of the Upper Owl Creek Dam, such as demolishing the intake tower, gates and pedestrian bridge, provide upstream closure for the two outlet conduits and other needed repairs. It also requires the raising of the upper dam four feet with earthfill, thus requiring that the toe of the dam be extended downstream. The upper Owl Creek dam is a 1,300-foot long earthfill embankment with a slender concrete core wall located along the centerline of the dam. The nine-inch core wall is reportedly founded on rock over most its length, the left side is reportedly founded on natural soil.
The dam has a maximum height of about 38 feet and the upstream slope is covered with hand-placed sloped riprap, while the downstream slope is covered with tall weeds and brush. Its labyrinth spillway, which will be moved closer to the center of the dam, is located on an abutment and consists of a 50 foot concrete trapezoidal weir and chute. The well-known water intake house will also be destroyed and new system built closer to the breach of the dam. The spillway chute converges with the valve house's drainage channel and eventually drains into the lower dam which withdraws into the Little Schuylkill River.
Currently, drawdown is provided through a concrete intake tower located in the reservoir at the upstream toe of the dam. Two 20-inch diameter cast iron pipes encased in concrete extend through the embankment to a valve house located at the downstream toe of the upper dam.
Jennifer Kowalonek, PE, LEED AP, Project Manager with Benesch Engineering, and Rob Jones, Tamaqua Public Works Director, stated that sediment deposit levels, well-being of aquatic life, water temperature and oxygen levels will be watched and monitored during the drainage. The Tamaqua Borough received $5,322,400 in grant funding for rehabilitation of the Upper and Lower Owl Creek dams via the H2O PA High Hazard Unsafe Dam grant program. The Lower Owl Creek received $1,668,000 and Upper Owl Creek received $3,654,400. The Tamaqua Borough is responsible for about 20 percent of the total cost. Repair work to both dams is expected to be advertised and put out for bid in the next few months and could possibly involve two contracting companies. The grant also requires the repair work to both dams to be completed by July 2012. "Owl Creek dams are a valuable and beautiful natural resource, and we would not be able to make these much-needed improvements without this funding," said Tamaqua Borough Council President Micah Gursky previously. "I am thankful that this funding will allow us to preserve this vital resource for future generations." After final completion of the project, both drainages to the dams will be closed to allow the reservoirs to fill back up with water and be used for recreational purposes. Jones pointed out that, under normal conditions, work to both the upper and lower Owl Creek dams is projected to be completed by the summer or early fall of next year.
The grant also requires the repair work to both dams to be completed by July 2012.
After final completion of the project, both dams will be closed to allow the reservoirs to fill back up with water and be used for recreational purposes.
Jones pointed out that, under normal conditions, work to both the upper and lower Owl Creek dams is projected to be completed by the summer or early fall of next year.
On May 7, John A. Arway, Executive Director of the Pennsylvania Fish and Boat Commission (PFBC), lifted all seasons, sizes and creel limits on the upper Owl Creek reservoir in anticipation of the reservoirs complete drawdown. The temporary modification will remain in effect until further notice; but in no event will it remain in place after Jan. 1, 2012. The PFBC is encouraging fisherman to visit the upper Owl Creek Reservoir over the next few weeks and catch as many fish as they can before the reservoir is completely drained and construction begins to repair both dams. Dave Miko, Chief of the PFBC Division of Fisheries Management said in a previously published interview, "Removing all harvest restrictions provides additional recreational opportunities for anglers and can help reduce the number of fish that could potentially be stranded when the water level drops. He added, "Once the draining of the reservoir begins, all public access to the facility will be prohibited."