Dinosaur Historic Structure Report Quarry Visitor Center

EXECUTIVE SUMMARY

Introduction

The Quarry Visitor Center at Dinosaur National Monument, recognized as a National Landmark and one of the most significant structures produced by the Mission 66 program, is in dire need of stabilization treatment. It could be argued that in its current state, the Quarry Visitor Center is marginally habitable. Despite major interventions over the years, the building continues to move, even as this report is being written. Due to the advanced nature of the structural failure, there is primarily only one recommended alternative for treatment presented in this report: total replacement of the South and Administration wings. This will result in the reconstruction of both wings to their former 1958 appearance, reusing as many architectural features as possible. In addition, the Exhibit Shelter is in need of rehabilitation and modification to complete the stabilization treatment.

Overview of Recommended Treatments and Use:

Stabilizing the Quarry Visitor Center will be a highly unusual, if not paradoxical, undertaking because the period of significance is an extremely short time frame: The National Register Nomination cites "1957-1958". Essentially, this is the period of time during which the structure was initially constructed and first opened to the public (dedicated on June 1, 1958), prior to few if any subsequent modifications. Therefore, the recommendations set forth in this report lean heavily on a combination of the original design documents and verification of their execution. Known alterations, implemented after the period of significance, are recommended to be removed. Conversely, known historic (executed during the two-year period of significance) design features are recommended to be restored to, or retained at, their historic 1958 appearance. Features of unknown origin are recommended to be retained in place, or salvaged and reinstalled, if they have to be removed.

Below is a summary of the primary recommended treatments presented in this report:

• Move, rehabilitate, and reinstall historic serpentine entrance ramp on a new expansive soil tolerant foundation.

• Demolish and reconstruct the Administration Wing, salvaging, rehabilitating and reusing historic window wall frames, windows, doors, door frames, characterdefining finishes, and stair assembly. A new expansive soil tolerant foundation will be installed.

• Demolish and reconstruct the South Wing, salvaging, rehabilitating and reusing historic window frames, windows, doors, door frames, and character-defining finishes. A new expansive soil tolerant foundation will be installed.

• Demolish and reconstruct the Visitor Gallery second floor concrete deck and floor slab below.

• Salvage Exhibit Shelter stair assembly. Rehabilitate and reinstall as part of South Wing and Visitor Gallery reconstruction.

• Rehabilitate the Exhibit Shelter exterior steel frame and glazed wall system by removing and reinstalling historic glass in a flexible glazing system.

Since the period of significance does not cover a period of time when the Quarry Visitor Center was substantially in operation (one summer), it is difficult to recommend any ultimate use that does not in some way conflict with or modify the character-defining features. With that in mind, this report recommends restoring the structure to its initially-constructed appearance, the only variance from the original design being accessibility, egress, and structural treatments. Further analysis of a future program for use, interpretation, and their subsequent impacts on the Quarry Visitor CenterÕs National Register qualities, will have to be evaluated as they develop and then weighed during the schematic design process. The Historic Structure Report will set the philosophical sideboards for these discussions.

This report is not intended to be the schematic design for treatment; rather it is baseline information for future use in preparation of the final design program, future schematic design and construction documents.

Research, Findings and Major Issues:

Initial Historic Structure Investigation performed on January 21 through 23, 2003

Ron Shields, Project Manager, Denver Service Center
Dave Snow, Supervisory Historical Architect
Geoff Yost, Architect
Bruce Keller, Job Captain and Structural Engineer
Mark Matheny, Geotechnical Specialist

PURPOSE:

The purpose of the field visit was to perform the initial investigation required for the preparation of a Historic Structure Report. Overall, the structure was found to be in an advanced state of structural distress and deficient in Life Safety Code compliance.

DISCUSSION:

Fire and Life Safety (Egress)

There is only one exit from the building, which serves both park staff and visitors. The two existing public entries at the east end are so close together (even though they are on different levels) they are considered as one exit. Sizable groups of visitors congregate at the second-floor mezzanine and first floor visitor gallery. Egress is neither adequate nor code compliant. In a fire or catastrophic event (falling glass), the visitors are at risk. By code, additional emergency egress is required. Additionally, neither public nor staff areas are completely protected by a fire suppression system. An early warning fire detection and alarm system is required by policy - (D.O. 50B, Reference Manual 50B, Section 12.2.A.5 & 6).

According to DirectorÕs Order 58, the AHJ (Authority Having Jurisdiction) in these matters is the Regional Structural Fire Management Officer, Bruce Goodwin.

Occupational Safety and Health

Due to prolonged structural movement over the years caused by expansive soils under building foundations, openings now exist in the building envelope, allowing access by rodents. This has created an active infestation, thus raising Hantavirus, rabies, and other sanitation concerns. Other hazards to health could include the following products. Window glazing putty likely contains lead and/or asbestos (samples taken will be tested). Lead paint, halon gas, asbestos pipe insulation, and radon gas are likely part of or affect the building environment.

Roof Drainage

Historically, the Exhibit Shelter roof had six drains discharging to ground level. Currently, there are still six drains from the roof, but they all connect to one pipe that is no larger than any one of the six original collectors. In the event of a heavy rain, the current drainage configuration could be overwhelmed, forcing the storm overflow into the moisture sensitive foundation soil at the building perimeter. Additionally, due to the exposure of this main roof drain in the unheated upper reaches of the gallery above the mezzanine, freezing is a possibility.

Currently all roof drains discharge into the sanitary sewer system and there is potential for the NPS sewage treatment plant at the base of the hill near the maintenance and residential area to overwhelmed.

Habitability

The staff offices and public restrooms are marginally habitable. The swelling of subsoils beneath office floor slabs has caused the floors to heave and slope in two directions, with as much as 8 vertical inches in 15 horizontal feet. Supplemental workstation floor systems are now required to utilize these offices.

Toilet fixtures in the public restrooms are far enough out of plumb to make a normal flush exit the bowl and deposit waste water on the floor.

Glazing

The Exhibit Shelter window walls are not constructed like a typical contemporary curtain wall, rather the glass is integral with the structural system. All window mullions and muntins are steel channels welded to the structural wall assembly which acts much like a rigid steel framework. Accordingly, any movement of the structure exerts shear stresses on the glass. There have been numerous instances of window panes spontaneously breaking. All that holds the 36" by 36" glass panels in place are small wire retainers and putty. The lack of flexibility in this window system increases the likelihood of glass breakage when the structure moves with the soil expansion. It appears that most of the glass is non-tempered float glass. Park staff has applied an interior plastic safety film to help consolidate any breakage, but its effectiveness is unknown.

Accessibility

Only the first floor is accessible to handicapped visitors. All public toilet facilities are located on the second floor and the toilets and stalls do not meet ADA requirements. The exterior ramp, a primary character defining feature, is an illusive detriment to visitors in wheelchairs by "appearing" to be accessible when in fact it is not because it is too steep and to long without landing.

Soils

The primary cause of distress to the building is the expansive soils. The building is founded on a shallow foundation system that is not strong enough to resist soil swelling and uplift. The soils have a very high expansive, or swell, potential when moisture comes in contact with them. The drainage in the area of the building has been improved but from conversations with the park staff and visual observation, parts of the building are still moving due to swelling of the soils. The upward movement of the soil has caused interior slabs to heave as much as 8 inches and because of the construction of the viewing area and gallery, this upward movement has caused the interior viewing gallery to drop by as much as 12 inches. In addition, the entry ramp to the second floor near the entrance has broken at its support and separated from the building due to movement. Non-historic, visible, structural steel columns and beams currently support the ramp above the entrance. Cracks are also evident in the side walls of the ramp at each pier support suggesting the pier supports are also moving. It does not appear that drainage improvements alone have significantly reduced the potential for movement caused by the expansive soils.

Structural Distress

The continuing deterioration of the Quarry Visitor Center has been documented in previous trip reports and memoranda. Please refer to "Chronology of Use and Development".

Of particular concern are the continuing movement of the floor slabs in the laboratory areas and administrative wing and the progressive cracking of interior wall sheathing in the laboratory areas and widening cracks in the exterior CMU of the administrative wing. These problems are related to the movement of surface soils which is causing floor heaving and excessive stress in interior partition walls.

Some of the interior walls near the laboratory spaces span between the concrete floor slab and the steel roof beams. These roof beams cantilever into the exhibit shelter space to support the second floor visitor gallery. The lifting of the floor slab under these wood framed interior walls is causing the wall framing to be crushed between the floor and the roof beams. This causes cracking in the drywall of the walls and may lead to buckling of the walls or breaking of the anchorages for the roof/gallery support beams. The lifting of the roof beams also causes compression in the south glazed curtain wall of the exhibit shelter. This stress causes cracking of the glass panels and can lead to falling glass on the visitor gallery.

Shallow footings under these interior walls and under the circular shaped exterior masonry walls of the administration wing are being moved by the soil expansion. This is causing severe distortion to the cylindrical shape of the building. The distortions result in the circular roof deck buckling into an elliptical shape. Progressive cracking is evident in the exterior walls and bowing is apparent in the interior walls.

Although the structural system is tenuously stable at present, un-checked deterioration of the distressed roof, floor deck, or a buckled interior wall may result in sudden redistribution of loads and a chain reaction of material failures. At a minimum, this condition aggravates the ability of the park maintenance staff to seal the building from infiltration by air or vermin. While currently not a life-safety hazard (we are reasonably sure), future movements or distress could indicate the beginning of a rapid sequence of damage that could ultimately require closing the area to the public. The operation of the building currently requires any new or significant progressive damage in the walls or ceilings of the administration area be immediately reported to a building professional for safety evaluation.

Utilities

Most of the building and utilities distress is related to and caused by expansion of the supporting soil and rock strata beneath the building. These materials are moisture sensitive and expand with great pressures if moisture is introduced. The following memorandum previously indicated some of the sources of water and recommended repairs to the buildingÕs utilities:

Memorandum to: Regional Director, Rocky Mountain Region From: Chief, Professional Support Division, Denver Service Center Dated: Aug. 31, 1989

Our understanding is that the recommendations were implemented. However, a regular review of this memorandum would be useful to ensure on-going utility maintenance and testing is properly conducted.

RECOMMENDATIONS:

1. Develop a Fire Protection and Life Safety Master Plan to address the fire and life safety deficiencies. A performance-based (use of owner-set criteria) approach may be appropriate to address the unique characteristics of this facility.

2. A second emergency egress for the public should be developed at the west end of the building.

3. Consider alternate staff offices locations.

4. Review possibilities to accelerate out-year construction funding.

5. Develop an interim strategy for the safe use of the building and health of all its occupants.

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