Casa Grande Ruins Administrative History

APPENDIX F: CASA GRANDE RUINS NATIONAL MONUMENT
NATIONAL PARK SERVICE BUILDINGS (continued)

Ruins Shelter Roof

Although this 1932 shelter roof has no unique engineering or architectural features because it was constructed by using common steel frame techniques of the day, it has historical importance. Even though it was not the first roof to cover the Great House, this roof represents early National Park Service preservation efforts. Consequently, this structure will be nominated to the National Register of Historic Places.

By the mid-1920s the original shelter roof had begun to deteriorate. Although Frederick Law Olmsted, Jr. designed a new roof in 1928, a design competition was soon held. It was not until 1932, however, that funds were appropriated to build the roof. Consequently, the Chief National Park Service landscape architect, Thomas Vint, became involved with the roof design. He wanted a distinctive roof, not one that would blend with the ruins. The National Park Service Director, Horace Albright, however, advocated that Olmsted's design be followed. Olmsted planned a structure with a hipped roof supported on leaning posts that was secured with guy wires much like the ropes used on a circus tent. He designed the roof with these wires because he feared that the upward lift of the wind on such a structure could damage it and the ruins. [16]

On April 28, 1932 the National Park Service Washington office notified the San Francisco Field Office that funds were available to construct the ruins shelter. Soon thereafter, the design was finalized. For the most part, Vint followed Olmsted's plan with the exception that he omitted the guy wire arrangement and he made some changes in the cantilever trusses that supported the eaves. Otherwise, the hipped roof supported by leaning posts followed Olmsted's proposal. Allen Brothers, a bridge construction firm from Los Angeles, won the bid. That company sublet the excavation and footings to Clinton Campbell and the steel fabrication to the Virginia Bridge and Iron Company of Birmingham, Alabama. Campbell began work on September 19 to excavate for the footings. Soon thereafter, a railroad car of cement arrived along with 126 yards of gravel and sixty yards of sand. Campbell used that material to pour the footings. Each of the four, ten foot long footings was twelve feet square at the base and tapered to four foot, six inches at the top. The footings weighed seventy-eight tons each and had eight, one and one-half inch diameter bolts, twelve feet long imbedded in the concrete. The roof support columns were attached to these bolts. [17]

Before construction began on the new roof, the old 1903 shelter roof was removed and a temporary timber shelter erected over the Great House. The old roof was in such poor condition that it would not have protected the ruins from potential damage during construction. [18]

Figure 50: Ruin Shelter Roof.
Constructed in 1932 to protect the Great House.

When the new ruins shelter was completed on December 12, 1932, it stood forty-six feet from the ground to the eaves. Four slanted columns of round, welded steel pipe with interior steel reinforcing supported the roof. A two-way steel truss system covered the entire bay of the hipped roof. The shelter roof had an overall dimension of ninety-eight feet north and south and eighty-two feet east to west. It had a slope of three inches in each foot. Its roof ridge was approximately fifty-eight feet, eleven inches above the ground. A copper louvered ventilator was designed for the roof ridge to reduce upward wind pressure. The highest point of the structure, the top of the monel metal ball used for a lightning rod, reached sixty-nine feet, three inches above the ground (figure 50). Its roof was covered with transite sheets of corrugated asbestos-cement material. Each sheet measured forty-two inches wide and six-feet, six-inches long and weighed ninety-six pounds. The sheets were fastened with bolts every twelve inches along each purlin. In addition the roof incorporated four corrugated glass skylights which measured six-by sixteen-feet on the short roof side and six-by thirty-two-feet on the long side. Lightning protection came from an eight- inch monel metal ball atop a two-foot vertical section of Bakelite tubing insulation which was screwed to an eight-foot hollow steel tube fastened to the center of the ridge. A three-eighths-inch strand copper cable passed through the tube from the ball and followed the hip rafter to the southwest corner column. The cable ran through that column and the concrete footing to be grounded to a one yard square, twenty-two gauge copper plate buried fifteen feet below the surface in a bed of charcoal and rock salt. Each of the four columns were grounded in a similar manner. The roof drainage was accomplished by an eight-by ten-inch copper gutter forming the roof cornice. Two, six-inch copper downspouts connected with two six-inch wrought iron downspouts placed inside the two west columns. Water ran from there through two, eight-inch vitrified clay pipes in the ground to a low point sixty feet west of the compound. [19]

In the final construction report, the National Park Service structural engineer, Edward Nickel, who supervised much of the shelter's construction, described the care involved in the roof's design and construction. What he wrote described the modifications that Thomas Vint made to Olmsted's design. Vint's concern was that, although a roof would have an architectural value of its own, it should be designed to contrast with the Great House ruin and not blend with it. It should not detract from the ruin that it was intended to protect. Nickel stated that,

In designing the various structural members consideration was given to the architectural proportions so that the final appearance of the steel frame would be the best possible. For this reason angle sections were used in place of channels in the trusses, with the least dimension vertical, resulting in the desired appearance of lightness to contrast with the massive adobe walls.

Greater symmetry and architectural beauty was obtained in the steel frame and bracing, by using sections of similar overall size where possible. [20]

Upon completion, the shelter was painted a sage green to harmonize with the mountains and vegetation as well as provide a contrast with the ruin's walls. In subsequent years, little maintenance has been required for the shelter beyond periodic repainting. In 1955 some cracks, that had appeared in the support columns, were welded. The last coat of paint, applied in 1989-90, changed the shelter color from sage green to light tan. [21]

Footnotes

1. Southwestern Monuments Monthly Reports, May 1932 and April 1934; Van Valkenburg, "Area History Casa Grande National Monument;" Casa Grande Superintendent's Annual Reports for 1976 and 1977.

2. Southwestern Monuments Monthly Report, January 1932, December 1940, January 1941; "The Six Year Program for the Casa Grande National Monument - 1934," 45-46; Master Plan, 1941.

3. Aubrey F. Houston to the National Park Service Director, January 15, 1964; Casa Grande Ruins National Monument maintenance records.

4. Southwestern Monuments Monthly Reports, November 1928 and April 1929.

5. information obtained from the monument maintenance records.

6. Ibid.

7. Information from the monument maintenance files; Addition to custodian's residence, June 30, 1940, Folder, 620-58 (CCC), Quarters for Employees (Res.) C.G., Container No. 789205, Accession No. 52-A-100, Record Group 79, Records of the National Park Service, Regional Archives and Record Center, Denver, Colorado.

8. Information from the monument maintenance files.

9. Information from the monument maintenance files and the List of Classified Structures; Donald L. Spencer to Chief Archeologist, Western Archeological and Conservation Center, August 27, 1987, Casa Grande Ruins National Monument Outgoing Correspondence File July 1, 1987 — December 31, 1987; Final Construction Report — Oil House — Approved CCC Project 52, June 30, 1939, Folder, 620-105 (CCC) — Oil Station C.G., Container No. 789205, Accession No. 52-A-100, Record Group 79, Records of the National Park Service, Regional Archives and Record Center, Denver, Colorado.

10. Information from the monument maintenance files and the List of Classified Structures; Final Construction Report — Warehouse-Approved CCC Projects 51 and 69, January 16, 1940, Folder, 620-100 (CCC) — Warehouse, Container No. 789205, Accession No. 52-A-100, Record Group 79, Records of the National Park Service, Regional Archives and Record Center, Denver, Colorado.

11. Information from the monument maintenance files and the List of Classified Structures.

12. Information from the monument maintenance files and the List of Classified Structures.

13. Information from the monument maintenance files.

14. Information from the monument maintenance files; Final Construction Report — Pump House — Approved CCC Project 74, July 24, 1941, Folder, 620-54 (CCC) — Pump House C.G., Container No. 789205, Accession No. 52-A-100, Record Group 79, Records of the National Park Service, Regional Archives and Record Center, Denver, Colorado.

15. Information from the monument maintenance files.

16. "Casa Grande Ruin Shelter: — (Nickel);" Final Construction Report on Casa Grande Ruin Shelter by Edward A. Nickel, January 1933; Thomas C. Vint to the National Park Service Director, March 20, 1931; Frederick Law Olmsted, Jr. to Horace M. Albright, March 26, 1931.

17. Arizona Republic (Phoenix), September 25, 1932; Rose to Watson Davis, Managing Editor, Science Service, Washington, D.C., September 29, 1932; Southwestern Monuments Monthly Reports, May and September 1932.

18. Nickel, "Final Construction Report on Casa Grande Ruin Shelter," January 1933; Southwestern Monuments Monthly Report, October 1932.

19. Nickel, "Final Construction Report on Casa Grande Ruin Shelter," January 1933; Attwell, "3 Roofs in 1,000 Years," 27; Information from the List of Classified Structures; Southwestern Monuments Monthly Reports, May 1932.

20. Nickel, "Final Construction Report on Casa Grande Ruin Shelter," January 1933.

21. Southwestern Monuments Monthly Reports, April 1955.