Sphinx Cave - Bat Gating Project
Coronado National Forest, Arizona.

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A safety briefing was held, both at the staging site near the vehicles and again outside the cave, prior to work beginning at either location. The focus of the brief was the safety of the workers and to minimize the impact to the cave.   Work was initiated at the site by moving unstable rock from the vicinity, making the area safe to work for the teams.   Moving breakdown rocks that would later be used to reinforce the footer of the gate also required several people. Crews then set to dressing up a few of the attachment points for the gate to the rock. After clearing the site and moving the welding equipment, powered by a generator outside the cave, to the site, work was begun on the setting of the anchors and footers. Two welding teams worked the site at different points, while another team moved rocks and mixed concrete for the final installation. All teams wore appropriate safety equipment, including helmets, safety glasses, gloves, and respirators where appropriate.


Safety Meeting

Safety Meeting Before Beginning any Work


Gate Placement

Gate Inside of Cave and Ready for Placement


This bat gate, as with most, was to be installed nearly perpendicular to the flight path of the bats that use the cave.   This configuration allows the bats to pass most comfortably through the gate, thereby eliminating the risk for them to be intimidated by the gate and not returning. The gate location pictured here proved a convenient spot for installation. It is small, requiring fewer materials, and still close enough to the entrance to be accessible to our installation equipment such as welders and concrete.   



The gate is made of heavy mild steel, 2 x 2 inch tubing, reinforced with re-bar and concrete inside the tubing. The welding has continuous seams all the way around each bar sealing and strengthening the gate bars. This gate design makes it very resistant to decay and possible vandal attacks. The dimensions of the gate are approximately 36 inches wide and 24 inches tall. It took 2 people almost an hour to carry the gate nearly one quarter of a mile from the staging site to the cave entrance. Due to its weight, water was pumped from a US Forestry Fire truck parked at the staging site to large plastic trashcans located just inside the cave entrance. This water was used for the concrete mixing. Re-bar reinforcements, steel mounting anchors and many yards of concrete make this gate very resistant to vandalism and damage from the elements. We also inset rocks and buried the concrete to make the area around the gate look as natural as possible.

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Bat Gate Mounting

Welding the Bat Gate into Position


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