Casa Grande Ruins Casa Grande Ruins National Monument, Arizona: A Centennial History of the First Prehistoric Reserve 1892 - 1992

The protection and preservation of a precious and valuable resource was utmost in the mind of Sylvester Baxter when he sought to convince influential Bostonians to lend their support to have the Casa Grande ruins preserved for the future. It was through the efforts of these people that the first preservation and protection measures were taken in 1891. This early stabilization work, combined with future endeavors, has attempted to stop natural deterioration and repair damage. Although it has frequently proved to be a maze of dead ends, the preservation objective has remained a vital part of the monument management. The construction of shelter roofs over the Great House, combined with major stabilization efforts in 1906-08, 1924-28, 1955-56, and 1967, has slowed natural deterioration. Besides these endeavors, experimentation with chemical preservatives occurred in the 1930s, 1940s, 1970s, and 1980s in an attempt to harden the earthen remains against erosion. The ultimate, but not final, solution in this ongoing effort for stabilization has been the use of a commercial cement binder product called Daraweld-C to produce "Amended Mud" which is coated on the remains by using whisk brooms.

Because it was the most visible and spectacular part of the prehistoric remains, the first preservation efforts focused on the Great House. In 1891 a $2,000 appropriation was used to underpin the walls with brick as well as fill the largest, lower wall holes. The surface of the brick in these holes was set back one inch from the face of the walls to allow the brick to be covered with a concrete plaster. Some lintels over doors and windows were replaced and the cavities above them were filled with brick. Three internal braces were used to support the south wall. In October 1902, S. J. Holsinger did not approve of the use of brick or concrete on the ruins. He felt that restoration work should be done with original material. If an ambitious program had been developed at that time to periodically repair the ruins with caliche, the walls probably would not have suffered as much. Even if such a plan had been developed, the frequent lack of preservation funds would have prevented its implementation. Holsinger's major accomplishment, however, was not the development of a policy to use natural material for repairs, but the design of a corrugated iron roof supported on redwood posts which was built over the Great House in 1903. [1]

In the period 1906-08 J. Walter Fewkes spent two winter seasons at Casa Grande. Part of his work involved exposing more than half of the room walls and the entire enclosure walls in Compounds A and B. This effort amounted to uncovering some 100 rooms. Fewkes did not replace the earth over the walls. The intent, in keeping the walls exposed, was to provide an additional attraction for visitors. Occasionally, decisions regarding interpretation made preservation more difficult. Fewkes recognized that the uncovered walls would be subject to deterioration, but, he thought, the greatest threat to the walls would come from moisture undercutting or sapping them. In Compound A, his solution to keep water away from the base of the walls was to grade the surface and dig a series of drainage ditches to conduct water to the northeast corner of the compound. From that location the water was diverted to a depression 200 feet northeast of the compound. In addition Fewkes placed a layer of concrete along the base of the Compound A walls to prevent undermining. In Compound B, Fewkes dug a drainage ditch around the outside of the compound wall. [2]

Left uncovered, the compound and room walls soon began to erode from the action of rain and wind. Beginning with his annual report for fiscal year 1910, Pinkley noted the erosion, but he concluded that there was no practical way to protect the walls. Consequently, the walls were left to the effects of nature for the rest of Pinkley's first custodianship and that of James Bates, Pinkley's successor. Although he was unsuccessful, Bates did advocate putting a concrete cap on the exposed walls to keep them from crumbling. [3]

When Frank Pinkley returned as custodian in 1918, he began to give some thought to a means by which the exposed walls could be protected. He wrote to National Park Service Director Stephen Mather that he had considered spraying the walls with silicate of soda, but he did not do so. Instead, Pinkley asked Fewkes to send him suggestions for wall protection. Fewkes replied in May 1918, but that letter does not exist. One can only guess that he had not changed his views in the time since he had excavated the walls. When Pinkley sent Mather his idea of the causes of wall destruction in July 1918, he repeated Fewkes' earlier conclusion that water rising by capillary action caused sapping or erosion at the base of the wall. [4]

Despite his concerns, Pinkley received no preservation money until the 1925 fiscal year which began July 1, 1924. Preservation work continued until February 1928 with the initial goal to stop wall sapping. Following that work, a concrete cap was placed on the walls as a means to prevent crumbling of the soil. In the first two years, repair work concentrated on Compound A. George Boundey, who became Pinkley's full time assistant on July 1, 1924, was placed in charge of the work. With two Pima men to aid him, Boundey ran a trench along the inside and outside of the walls for some two feet below the floor line. Then the wall surface was covered with concrete for about two feet above and below the floor level. By the end of April 1925 the base of Compound A walls had been covered in that manner. Soon thereafter and continuing into 1926 the walls were given a concrete cap. Some of the exposed walls were given a concrete coating. Daring the winter of 1927-28, Martin L. Jackson, the Montezuma Castle custodian, supervised the stabilization work. More exposed walls in Compound A were given a concrete coating. Stucco was placed on the concrete coating that Mindeleff had used to cover the great house brickwork in 1891. Concrete plaster was used on two groups of rooms to the east of the Great House and on the multi-story remains to the southwest of that structure. Areas where the concrete wall cap had cracked or broken off were patched. [5]

When Thomas Vint visited Casa Grande toward the end of 1930, he and Pinkley discussed ruin preservation techniques. Pinkley decided that he did not like coating walls with concrete. He found it objectionable because it hid the walls. Consequently, Pinkley and Vint talked about the possibility of using some transparent waterproofing chemical to coat and harden the ruin walls. Toward the end of January 1931, Vint wrote to Pinkley to tell him that he had obtained a gallon of a product called Dehydratine which was manufactured by the A. C. Horn Company. Vint's action evidently caused Pinkley to decide that it was time to more actively seek a chemical preservative. Pinkley replied that he would test the product on the ruins. At the same time, Pinkley sought more information on the subject of waterproofing materials. He wrote to the Bureau of Standards in Washington, D.C. to request a copy of "A Preliminary Report of Exposure Tests on Colorless Waterproofing Materials" published in 1921. Pinkley evidently took one further step to obtain chemical preservatives. In early February 1931, a National Park Service article titled "Solution to Preserve old Masonry is sought" appeared in newspapers almost nationwide. This appeal brought letters from companies in such states as New York, Michigan, Ohio, California, and Arizona with offers to send test samples. [6]

The newspaper article resulted in a flood of chemical preservatives being sent to the monument. When tested on small wall areas, none gave satisfactory results. The Horn Company product Dehydratine #2 turned dark. A liquid "Ankerite", received from the Lucille Chemical Company of Glendale, California, was not quite colorless and it gave the test area a glossy appearance. After four months, it cracked. Product samples continued to arrive at Casa Grande from 1931 into 1934. This parade of products carried such names as Amoglaze, Inwood, Stucco Waterproofing Compound, Oronite Waterproofing, Hornstone Crystals, Forex, Unicrete, Permo #4, and PeneTex. Some companies sent representatives with samples to apply on test areas. In November 1932 an agent of the Air-Spray Company of Washington, D.C. applied two test applications of his material on eighteen small wall areas. By January 1933 the product had cracked and in March of that year it began to peel from the wall. [7]

L. E. Peterson of the Truscon Laboratories in California came on April 20, 1933, to apply his company's product "PeneTex." Since rain had made the walls wet, he had to delay his experiment. Consequently, he talked Custodian Hilding Palmer into letting him remove a small section of the concrete plaster so he could apply the chemical to a dry area beneath the concrete. To their surprise, the wall section under the concrete plaster had decomposed for varying depths. A wall segment that had never been plastered was in better shape than the concrete-covered walls. Peterson and Palmer decided to remove several more sections of wall plaster. They found that the caliche in these areas had also become a powdered mass which fell out when the concrete was removed. In addition these exposed sections contained much greater moisture, even to a considerable depth, than walls which had no concrete covering. The walls had absorbed ground moisture which was prevented from escaping by the concrete plaster. So, they concluded that no wall treatment would be successful until the absorption of ground moisture could be stopped. Peterson suggested that concrete mixed with Truscon Waterproofing Paste should be used as curtain walls to a depth of two to three feet below ground to stop the flow of a major portion of ground water. Once built it needed to be coated with PeneTex. Peterson also advocated that drain tile covered with gravel be placed below the curtain walls. [8]

Hopeful that curtain walls were the answer to ruins preservation, Custodian Palmer requested that a Park Service engineer read Peterson's report. Assistant Engineer J. B. Hamilton came to the monument and examined the ruins. He consented to a curtain wall, but he cautioned that the trench for such a wall should not be dug straight down. To do so could cause the ruin wall to become unstable. Hamilton also warned that the concrete in a curtain wall needed reinforcement and expansion joints. As a result, Palmer decided to discontinue the experiment of spraying the walls with waterproofing material until curtain walls could be built. He, no doubt, expected to wait for some time to install curtain walls because he had no money. [9]

Fortunately for Palmer, the federal depression era work programs came to his aid. The brief Civil Works Administration program gave Palmer his opportunity to have curtain walls built. On November 21, 1933, he applied to have CWA monies used at Casa Grande for ruins preservation. Between December 1933 and February 1934 CWA workmen laid 600 feet of curtain wall along the south and west walls of Compound A. In addition, by grading the inside of the compound, the northeast water drainage, as established by Fewkes in 1907, was changed to the northwest corner. [10]

At the same time as the Casa Grande curtain wall work, the Engineering Section of the National Park Service field office in San Francisco obtained some CWA money to use for experiments with caliche and adobe preservatives. That office made an arrangement with Stanford University for laboratory space in which to conduct the work. F. A. Kittredge contacted Southwestern Monuments Superintendent Pinkley and asked that he send 100 adobe brick made from Casa Grande soil so that the waterproofing experiments could begin. He proposed to first perform a physical and chemical analysis of the adobe soil so that a determination could be made if a potential preservative would cause a chemical reaction with the soil. Kittredge hoped to find a colorless waterproofing fluid that would not peel or crack. In addition he sought to design a concrete cap which would keep wall tops dry. [11]

Pinkley had Casa Grande Custodian Palmer send ninety-seven adobe brick to Kittredge. Palmer evidently had no objection to turning over the preservative testing to the San Francisco field office. At the same time, however, he wanted to make sure that the new Park Service laboratory received a sample of his favorite waterproofing chemical. Within days of sending the adobe to Kittredge, Palmer wrote to M. J. Cavalier of the Truscon Steel Company in Phoenix and asked that he send a sample of PeneTex to be tested. [12]

In addition to Palmer's help, Kittredge asked companies that produced chemical preservatives to send samples of their products to the engineering laboratory. By March 28, 1934, fifty-two different preservatives had been received. Of that number, forty-three had been tested by August 18, 1934. Kittredge felt that only one of the forty-three chemicals had proved worthwhile. That solution, named Por-Lox, came from the Truscon Laboratories. His assessment, however, proved premature. By early March 1935 Por-Lox failed an ultra-violet test. [13]

When all the commercial preservatives failed to pass National Park Service tests, the field office engineering staff set out to develop its own product. Frederick Martius began with celluloid solutions, but any mixture over one percent proved glossy, and glossy material would not penetrate. Soon, however, Martius produced a colorless chemical that did not gloss but penetrated and was not affected by ultra-violet rays. He called this vinyl resin in acetone and toluene solution NPSX. On March 20, 1935, field work began at Casa Grande with that chemical. He covered several test areas in the southwest corner of Compound A with two coats of two, three, three and one-half, and five percent NPSX solutions. NPSX worked for two years, but when it was examined in 1938, in the third year, it failed to repel water. In fact the NPSX-treated areas absorbed as much moisture as the untreated walls. These results were very disappointing because NPSX cost too much to apply every two years. Consequently, it was back to the 1931 starting point to find a means to preserve the ruin walls. [14]

In mid-1939, frustrated with watching the old cement plaster scale off the rapidly deteriorating ruin walls, the Casa Grande Custodian A. T. Bicknell decided to experiment with "bitudobe." At the time, the Civilian Conservation Corps work force used this product to cover the exterior of the adobe buildings being constructed at Casa Grande. On June 27 Bicknell had two small wall sections of the Clan House coated with bitudobe. After a month it seemed to be effective. As a result, the custodian sought official approval to put bitudobe on all standing ruin walls. The value of bitudobe was never determined, however, because no funds were available to purchase it. At that point Bicknell settled for stabilizing ruin floors by using a caliche base with a top dressing of bitumuls oil. The CCC workers employed on that project had all the floors covered by September. [15]

Although the 1930s tests failed, Casa Grande and Southwestern Monuments personnel could not give up on chemical preservatives. Charlie Steen seemed determined to find some liquid that would work. In the spring of 1940, he removed the concrete cap from the east half of the Clan House. Then he dug trenches beside and under those walls in which he placed a six-inch curtain of caliche waterproofed with emulsified asphalt. As the final step he sprayed the wall area with two coats of "Themec" which was an emulsified cement paint. In a month the Themec turned lavender and in a year it had cracked and peeled. [16]

Monitoring equipment was installed for the first time in the Great House during the summer of 1940. Brass rods were placed across the corners of the building in such a way as to show wall movement. Monel metal rivets were imbedded in the top of the center walls of this structure to measure wind erosion. [17]

In 1941 heavy rains damaged the ruins. Because no satisfactory stabilization method had been found, the damage was accepted as an act of nature and no action was taken to repair the walls. Charlie Steen, however, undertook to backfill Compound F as a means of saving the remaining walls from further erosion. That compound had been excavated in 1930 and left exposed. Steen then applied for soil and moisture conservation work funds to backfill Compound E. The concrete cap at this site had failed and allowed serious wind and water erosion. He completed that job by March 1942. This compound was covered to a level of six inches above the walls by using the old excavated soil. Following the Compound E work, Steen backfilled the excavated area of Compound D. This site had been partly uncovered by Fewkes in the 1907-08 era. [18]

In 1943 Charlie Steen turned his attention to Compound A. In January and February he removed the concrete cap from the south and west walls and the old concrete plaster from about half of the walls. Steen replaced the old concrete work with a cement stabilized soil. Work was halted prematurely because the war had caused a labor shortage. [19]

Lack of money and a labor shortage prevented further preservation activity until after the Second World War. Although he had read about the earlier experiments with chemical preservatives and had done some testing himself, Charlie Steen still hoped to succeed where others had failed. He decided to perform more tests with water-repellent products. In these experiments to find an adequate preservative, Steen spent October and November 1946 at Casa Grande treating caliche walls and blocks with eight commercial products. He began with test areas on the Clan House walls, but switched to caliche blocks which he obtained from the nearby prehistoric Adamsville site. Of the eight water-repellent chemicals, Ethyl Silicate seemed the most promising. It, however, had no long-lasting effect. One product, Sodium Silicate, which had been suggested by Frank Pinkley in 1918, failed. Of the other substances, Diamond Seal resisted water for only several minutes. PeneTex, Hilding Palmer's favorite from the previous decade, separated with its oil being absorbed but not the wax portion. The kerosene-based wax substance, Dehydratine 2a, left a dark stain without soaking into the soil. Paraffin, a wax mixed with white gasoline, did penetrate two inches. Emulsified Asphalt did not work because of the high salt content in the caliche. Steen merely listed the last product, Synasol, without comment. [20]

Since the 1930s experiments with chemical preservatives had involved only surface applications, Steen decided to use other methods on the Adamsville caliche blocks. He tried to drill holes in the caliche, but frequently the blocks would break when the drill encountered a pebble. Absorption in holes, however, was hardly greater than with surface treatment. A capillary action test failed from lack of absorption. Steen tried to force liquid into the blocks under low pressure, but this attempt failed "miserably." Placing a block in a liquid in an effort to have complete saturation only caused the block to become soft and weak. Like his predecessors, Steen had to concede defeat. In any case, sealing the walls with a water-proofing agent could only promote greater damage to them if the capillary action of ground water could not be controlled. [21]

Considering that the greatest threat to the ruins walls came from ground water, which entered the walls through capillary action, the focus of preservation efforts changed in early 1947 to that problem. Steen proposed that a system of tiled drainage ditches be placed along the walls of Compounds A and B as well as the Clan House to divert ground water from them. He also advocated using caliche for repairs rather than concrete because concrete, especially when used as a cap, would trap water in the walls. [22]

Steen returned to Casa Grande on February 11, 1948 to begin stabilization work on Compound A. He dug a drainage trench around the walls of the north building in that enclosure and filled it with paper and pea-sized gravel in an attempt to stop ground water from entering those walls. All of the previous wall capping was removed and replaced with a two-inch-thick caliche cap. When it dried, it cracked, but Steen brushed a caliche grout over the cap with a straw broom. It successfully filled the cap cracks. Undercut walls were covered with a wire mesh and coated with caliche. A source of caliche on the monument caused Steen problems, but he finally obtained a "good" supply from the Arizona State Prison at Florence. [23]

In the next stabilization phase, Steen focused on Compound B. He, along with Gordon Vivian and Raymond Rixley, came to Casa Grande in February 1949 to begin that project. Rixley remained to oversee the work of replacing the concrete wall cap with caliche. On this occasion Randolph served as the caliche source. In early April, after recapping all but the west and half of the north compound walls, the work had to be abandoned for lack of money. Rixley remained for another week to install drain tile through some Compound A walls. Two months later, on June 29, Steen filed a proposal for the next fiscal year to complete the Compound B work and cap the walls of the Clan House. Despite the fact that, on July 23, 1949, a bad rainstorm damaged the Compound B walls that Rixley had not stabilized, no funds were available to repair ruins walls until 1955. [24]

In 1954 John Davis, the General Superintendent of the Southwestern Monuments, wrote to the Region Three director about an urgent need for money to stabilize the walls of Compound A and the unfinished part of Compound B. This reminder that no work had been done at Casa Grande for five years finally brought funds for stabilization in 1955. Roland Richert and Gordon Vivian worked between February 3 and March 8, 1955 on a major stabilization effort on Compound A. They had originally planned to cap and veneer the walls with caliche, but they were unable to make a suitable caliche, sand, and chat mixture that would work. Therefore, they fell back on the old concrete-stabilized soil solution. Before the veneer was applied, trenches were first dug along each wall to a depth of six to twelve inches to encounter Fewkes' 1906-07 concrete apron and Steen's 1948 gravel-filled trench. The walls were cleaned by raking away loose material, and then a new wire net was placed on them where needed to hold the cement-stabilized soil in place. The new veneer on the north building walls was sprayed with Daracone, a silicone water repellent, as an experiment. As a final measure the trenches were backfilled. Only forty percent of Compound A had been completed when Richert and his crew left on March 9. The greatest amount of work had been done on eighteen room walls. [25]

A heavy rain on August 2, 1955, seemingly did not affect the newly stabilized area of Compound A. Superintendent Bicknell thought the area sprayed with Daracone fared better. At the Great House, however, a 338-pound piece of caliche fell from the upper part of the south wall. Bicknell hoped to have that area patched. [26]

On February 29,1956, Vivian and Richert returned to finish the stabilization work on Compound A. Working until April 3, they used the same procedures and techniques that they had used in the previous year. In addition they reinforced and patched the area from which the caliche had fallen from the Great House, and sprayed it with Daracone. That silicone substance was also sprayed on the walls of Font's Room as well as on the southwest building and the newly stabilized walls. At the staff's request the concrete steps were removed from the north entrance to the Great House and the doorway partly filled. In this manner the staff hoped to show visitors that the lower part of the Great House had been filled with earth in the prehistoric days and, thus, it was necessary to use a ladder to enter the building on the second floor. [27]

Funds to stabilize the walls of Compound B were approved for 1958. Consequently, Vivian and Richert returned between April 16 and May 19 to attend to those enclosure walls. On this occasion, Vivian and Richert decided that, since the thin, concrete wall veneer had never really worked, they would try to preserve these walls by enclosing them within new walls. These new walls would only cover the old ones, so that the new material would not have to bond with the old wall surface or be dependent on the prehistoric walls for support. To accomplish this task, they dug a twelve-to eighteen-inch-deep trench on each side of the compound walls to permit forms to be placed two inches away from the base of the walls. Vivian and Richert then filled the forms with a concrete-caliche mixture and tamped it to a height about two inches below the top of the prehistoric walls. The caliche came from a Coolidge Sand and Rock Company pit about five miles east of the monument. After the forms were removed, they sprayed the new walls with Daracone. The impression marks left by the forms were not removed from the new walls until 1972. [28]

Until 1967 little more stabilization work was accomplished at the monument. In December 1960, Richert inspected the previous work. He felt that the hand-mixed, concrete-stabilized soil used for a veneer on Compound A walls in 1955 was not holding up as well as that produced in a cement mixer the following year. Consequently, he thought that area should be replaced in 1962. Both Compound A and Compound B walls soon needed to be sprayed with another covering of Daracone. The asphalt floor in the Great House needed to be replaced. The last time it had been coated with bitumuls was 1939. When Park Service archeologist Albert Schroeder visited Casa Grande five weeks later, he echoed Steen's 1959 appraisal that the pyramids in Compound B and all of the Clan House needed to be backfilled. The Clan House, located about 300 yards southeast of the visitor center, had been excavated by Fewkes in 1907-08. Superintendent Houston thought that canal silt could be used for the fill. It seems that the Indian Service had been piling silt on the monument once more and had nearly covered the south fence. [29]

Gordon Vivian was supposed to backfill the Clan House in the fall of 1961, but he decided that he first wanted to experiment on part of a wall with an electro-chemical soil hardening technique. The process evidently proved a failure since no more correspondence was exchanged about the test. Consequently, Joel Shiner backfilled the Clan House at the end of March 1962 with earth obtained from the north side of a modern mound which was located just west of Compound B. By 1963, the backfill had eroded somewhat, so Vivian had more dirt placed on that site. [30]

Like many an archeologist before him, Gordon Vivian could not help but try one more chemical preservative experiment. On October 2 and 3, 1963, he sprayed thirty-four gallons of Texas Refining Company sand and adobe preservative on both sides of the largest east-west wall of Compound B. This epoxy solution darkened the wall and formed a glaze which continued to look wet although it had set up very hard. [31]

A major stabilization project focused on Compound A between March 6 and April 28, 1967 with some work done on Compound B. Martin Mayer performed maintenance work on all walls and buildings including the Great House. He either patched and/or replaced disintegrated soil cement caps and veneer on all walls and treated them with silicone. In the Great House, Mayer plastered the lintels over seven doorways, replastered loose and missing concrete stucco on the building's base, and repaired minor breaks and holes in walls. A new product, Daraweld-C, was mixed with the soil-cement to help new patches bond better. In Compound B Mayer sprayed silicone on the compound walls and stabilized rooms 3 and 4. [32]

In 1969 and 1970 Martin Mayer returned to Casa Grande to work on the Great House. During the winter of 1968-69 a five-pound wall section had fallen in the north room. In May 1969 Mayer inspected the room and repaired sections of the walls. The next year, during February, he stabilized an upper pair of holes in the east wall of the center room and an upper pair of holes in the west wall of the east room, as well as the cracks at the top of the walls. Mayer also reconstructed the doorway to the east room. [33]

W. E. Sudderth came to Casa Grande between May 16 and June 8, 1972 to continue the never-ending stabilization work. He patched cracks in the compound walls and a number of the rooms of Compound A. In addition Sudderth put a number of test finishes on walls to find the one that would be most in harmony with the Great House for uniformity of color and texture. He was instructed to apply the finish judged to be best to the walls of both Compounds A and B. He decided that a commercial product called Daraweld-C proved to be the most satisfactory. Daraweld-C was mixed with caliche and sand to produce an "Amended Mud" which was then applied to the ruins walls with whisk brooms. It was found that a coating of this brownish-colored substance allowed the capillary moisture in the walls to evaporate. The only disadvantage to Amended Mud was that it had to be applied every two years. Despite this fact, Amended Mud has been used ever since to coat the ruins walls. [34]

Although the walls of Compound B had been periodically stabilized, visitors had not been allowed to view this ruin since about 1945. A question of its interpretive potential arose in 1973. Duane Spears of the Arizona State University Anthropology Department received a contract to make test excavations at Compound B to determine the extent of original features and their condition. From this information, it was hoped that a decision could be made whether to further stabilize and interpret this compound or to backfill it. Spears found that many original features remained even though the ruin had been exposed since the Fewkes excavation in 1907-08. He determined, however, that the wall remains and other features had been badly eroded. Consequently, Spears recommended that the interpretive potential of Compound B did not warrant the cost of further excavation, stabilization, and maintenance. Further development of that ruin would only result in more damage from erosion. Spears advised that the compound should be backfilled as soon as possible. Temporary backfilling followed the conclusion of his tests with a second backfill in 1974. [35]

In late 1972 the structural stability of the Great House came into question. It was feared that entire wall sections could collapse and thus not only further destroy its prehistoric integrity, but also endanger visitors. A contract was given to James Kriegh and Hassan A. Sultan of the University of Arizona College of Engineering to study the Great House walls. Their study extended over approximately a year's time in 1973-74. They were to evaluate the stability of the Great House walls, and study and assess techniques to restore and maintain structural integrity. On July 14, 1973, just prior to their study, the interior of the Great House was closed to all visitors. It has never been reopened to the public. Kriegh and Sultan found that the walls of the Great House were unsafe since they were not tied together. They believed that an earthquake represented the greatest danger to the building. Consequently, the two engineers thought that the Great House needed both vertical and horizontal ties to improve its structural integrity. They recommended that pipes be placed in vertical holes drilled through the walls after which each pipe and hole would be filled with epoxy. The addition of horizontal pipes would make the building more rigid. Kriegh and Sultan were also asked to find or formulate a sealing chemical which could either be sprayed or painted on the walls. In testing twenty chemicals they found one to be superior to the others, but they suggested that experimentation be continued with four of the chemicals. As part of the trial, Kriegh and Sultan called for the installation of a moisture barrier which sloped away from the base of the walls as a means to stop capillary action. Otherwise, as in past experiments with waterproofing chemicals, water would be trapped in the walls. [36]

Kriegh and Sultan's stabilization recommendations for the Great House were ignored. Drilling holes in the Great House walls and filling them with pipes and epoxy was considered to be too drastic. Instead, a different plan was prepared which urged that the walls be stabilized by filling all the second-story beam holes, roof grooves, and erosion grooves with caliche. To follow this course of action meant covering over one-third of the culturally significant features on wall surfaces. In a meeting held at the monument on January 17, 1980, Howard Chapman, the Western Regional Director, decided not to follow this plan because it would destroy too many of the Great House features that were being preserved for the visitors' benefit. [37]

The chemical experimentation that Kriegh and Sultan suggested was also not done. Instead, a three-phase chemical research plan was developed by the Western Archeological Center. It was intended that the first two phases would involve the testing of chemical soil amendments to find one that would effectively protect badly eroded walls and the development of a durable overcoat mortar for soil cement walls which would give a more natural appearance. Twenty-eight test walls were constructed at Casa Grande from soil taken from the prehistoric Escalante Ruins. These walls were allowed to weather for nine months between March 1977 and January 1978 before they were treated with ten water-based chemicals. The effectiveness of these chemicals was monitored over a twelve-month period. They evidently were not found to provide protection. No overcoat mortar was tested. [38]

Phase three of the chemical testing on the experimental walls came about through a contract with the Arizona State University College of Engineering. Its purpose was to determine the effectiveness of electro-chemical treatment of earthen walls in terms of compressive strength, decreased capillary action, appearance, and weathering. The Arizona State engineers recommended the use of aluminum sulfate for an electro-chemical treatment. It increased the compressive strength and reduced capillary action. Thus, walls were subject to less weathering. This remedy also had less effect on wall color than other treatments. Again no action was taken to implement the study's recommendation. [39]

As part of the wall monitoring and stabilization program for the Great House, seven gauges were installed in the Great House walls in 1984. They are still in place. The purpose of these gauges has been to detect wall movement and changes in corner cracks. [40]

A plan surfaced in early 1986 to remove the old concrete plaster from the Compound A walls and merely cover the walls with Amended Mud. Believing that all of the preservation treatments over the years, with the possible exception of Amended Mnd, might have weakened the prehistoric caliche walls, Dennis Fenn, of the Western Archeological Center, recommended that the concrete plaster not be removed. He thought that to do so might cause irreversible damage to the original material. As a result, a decision was made to continue to apply the Amended Mud coating every two years with annual applications as needed. [41]

Compound B was again considered for re-excavation and stabilization in early 1986. In a meeting at Casa Grande, it was decided not to follow that course of action. Instead, the entire compound was given another backfill covering. Since erosion washes some of the dirt away, it has to be replaced about every six years. In that same year, to lessen water damage at the compound, the older closed pipe drainage system was changed to an open slide one. [42]

Experiments to cover the prehistoric caliche walls with concrete and chemical preservatives failed to adequately preserve them. On some occasions, these measures damaged the walls resulting in the loss of prehistoric material. Probably the best preservation technique, as advocated in 1902 by S. J. Holsinger, would have been the use of caliche for repairs.