Table of Contentss

Acknowledgements

Introduction

Dinosaur

Wright Brothers

Gettysburg

Pertified Forest

Rocky Mountain

Cecil Doty

Conclusion

Bibliography

Appendix I

Appendix II

Appendix III

Appendix IV

Mission 66 Visitor Centers Chapter 1

A Bentonite Foundation

The scenery at Dinosaur National Monument is colorful mineral deposits, valleys revealing strata millions of years old, and fantastic shapes carved into solid rock by centuries of erosion. For Mission 66 designers who might have become jaded by this environment, geological power made its presence known in the form of bentonite deposits underneath the visitor center. When exposed to water, bentonite sprang into action, expanding at a force strong enough to move steel girders. Even before the building was completed, the Park Service observed damage to the parking area. Radiating cracks were first observed and reported by Construction Foreman Davis in November 1957. [63] During the first year the building was open to the public, the park staff felt an unsettling vibration in the upper gallery. Lyle Bennett advised performing a vibration test on the balcony slab by placing wooden posts at several points under the overhang. According to Supervisor McCune Ott, who conducted the test, the vibration could only be corrected by installing a post at every beam, a solution unacceptable to the park. Since visitors weren't complaining about the vibration, however, no further action was taken.

In 1962, WODC drew up plans for the reconstruction of the plaza area in an effort to improve the drainage system. These included details of the roof drains and a longitudinal section showing the "typical subsurface drain." At this time, the Park Service installed an aluminum handrail on the ramp and laid down a cobblestone and concrete slab around and under the ramp, which was extended slightly. [64] Despite these improvements, the plaza continued to be a problem. In March 1966, the maintenance division regraded the ground on the north and south sides of the building, realigned the pavement slabs in the east plaza, installed steel pipeline for roof drainage, cut several French drains, and patched other problem areas. The next year, the San Francisco Planning and Service Center grappled with repairs to the visitor center building, which included replacing some of the existing footings with new twenty-foot-deep caissons. In addition, the Park Service extended the lower level lobby, installed new handrails in the gallery, and replaced several of the fixed-sash windows on the east and west wall elevations with operable sashes. [65]

The geological situation was not seriously analyzed until 1966, when Dames and Moore, consultants in applied earth sciences, revealed the presence of bentonite in the soil. Their evaluation indicated that additional damage could be avoided if moisture were kept out of the foundation. After the first intensive season of rain and snow, the bentonite began to move. [66] Eugene T. Mott, who had witnessed similar subterranean action at the Painted Desert Community, compiled a detailed description of the building's damaged areas after inspecting the structure in 1968. Mott's list included two pages of "widening floor tile joints," and cracks in walls and ceilings; the south wall may have settled two inches. Like his predecessors, Mott recommended removal of moisture in the foundation as the park's highest priority. But while others blamed bentonite, Mott thought that the loose, sandy soil around the building was the most likely cause of problems. According to his assessment, the "beautiful" building was "constructed properly"; it displayed solid workmanship and the design was "adequate for construction in a stable area." As far as the moisture problem, Mott had little advice but hoped to avoid a concrete border that would obliterate the landscaping around the building. [67]

Over twenty years later, a 1993 Park Service study reported that Quarry Visitor Center would have a very short lifespan if serious measures were not taken to solve drainage issues. Biannual reports on the water levels in the well holes and west manhole were requested. Even more recently, in 1997, Dinosaur was still "settling and moving," but the cause was determined as both bentonite and a subterranean fault. After structural evaluation, a team of Park Service specialists advised "an overall plan to manage and stabilize" the building, preferably supervised by an architecture and engineering firm or the Denver Service Center. [68]

CONTINUED

http://www.cr.nps.gov/history/online_books/allaback/vc1e.htm