Rehabilitation at a Historic Landmark Sparks Innovation
Who would ever think fabricated rock would be eligible to receive a preservation award? This was the facetious question that crossed my mind as I headed out with my fellow Preservation Awards Selection Committee members for an unusual site visit at none other than Diamond Head State Park, a state monument that is perhaps THE most iconic natural landmark in Hawai‘i. Known to the ancient Hawaiians as Le‘ahi, and better known today as Diamond Head Crater, it is the dramatic remnant of a once-active volcano consisting of a type of highly erodible rock called volcanic tuff. In 1908, the U.S. Army built a trail from the crater floor up the interior crater wall to the lookout at the Fire Control Station on the summit. This has become the Diamond Head Visitor Trail which now hosts nearly 1 million visitors every year. But this trail is not without its dangers; the volcanic tuff along the trail is prone to rock falls and rock slides that have long been a safety hazard. The trail hugs the tuff rock wall of the crater on one side, with railings protecting hikers against sheer drops on the other. The goal of this preservation project was to prevent hazardous rock fall from the unstable slopes while preserving the appearance of the historic visitor trail. The project included rockfall mitigation at 15 sites along the trail. The slopes of weathered tuff were highly fractured, with multiple cracks showing imminent potential for rock to fall directly on the trail and potentially injuring unsuspecting hikers. The scope of work consisted of clearing the slopes and scaling lose rocks, drilling and installing steel reinforcing anchors, and adding geo-composite drain strips to relieve hydrostatic pressure behind [...]