poe paddy state park Structural plate arch tunnel reline

Poe Paddy State Park Tunnel – 2016 NCSPA Rehabilitation Project of the Year

By: Lane Enterprises, Inc

Structural plate arch as a tunnel reline material was used to address safety concerns associated with falling rock fragments in a popular hiking/biking trail known as Poe Paddy.

The old tunnel was blast constructed around 1880 to an internal height of approximately 20-ft that became a hibernation locale to an Eastern Small-footed Bat population deemed an endangered species.

The reline design included the preservation of 5 to 7-ft of space below the existing tunnel ceiling to serve as a hibernation cave for the bat species.

The flowable fill reline encasement extended a minimum 1-ft above the arch as a floor to the cave, with several depressions to allow water to pool into small ponds 3 to 6-in deep for humidity control. The 307-ft curvilinear reline (radius of curvature around 745-ft) necessitated 10 horizontal elbows.

Bat friendly gates, designed to American Cave Conservation Association (ACCA) and Bat Conservation International standards, were installed in the headwalls at each end of the reline. They allow the bats ingress and egress for hibernation season. The different type and sized openings work together to regulate air flow mimicking what was naturally occurring before the renovation.
poe paddy state park Structural plate arch tunnel reline

Post-construction monitoring showed comparable humidity and temperature levels were maintained, and a recent hibernacula survey indicates a significant increase in the total number of bats using the site compared to a 2014 survey.

The success and importance of this project was further evidenced during a May 2016 dedication ceremony where numerous attendees and speakers gathered to celebrate the project completion alongside a continuous stream of foot and bike traffic through the renovated tunnel in the heart of Bald Eagle State Forest.
Congratulations to the cooperative undertakings of the Pennsylvania DCNR, NCSPA member – Lane Enterprises, Inc. and their partners for a job well done.
Originally published – August 23, 2016

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