Saturday, June 19, 2010

PAINFULLY PANELESS

The design of the Quarry Visitor Center utilized natural rather than electric light in displaying the bones. To that end, the building had expansive glass walls on the south, east, and west side to take advantage of the large amount of ambient light on the top of the hill. Those glass faces are one of the most striking design elements of the building. It was a brilliant and highly successful idea. However, as with most things in the Quarry Visitor Center, some difficulties popped up down the road.

First, as time went on and the building began to move, the glass walls came under stress. Glass cracked or sometimes an entire pane would pop out of its frame. They could be replaced, although over time glass was replaced with plexiglass to reduce dangers from falling glass. The plexiglass sometimes cracked, but more often the panes would bow but stay in the frame.

As heating and cooling costs rose, UV filtering plastic sheeting was applied to the plexiglass panels. This helped prevent cracked panes from falling out, but did little in the long run to control temperature. Over the last several decades much more energy efficient plexiglass and other plastics have been developed for use in windows. So it is no surprise that the design for the new building would include totally new glass walls. Just replace the old panes with the new ones and voila, problems solved! Well not quite….

First, as you may recall from an earlier post constant reader, the entire east glass wall has pulled off of its concrete foundation wall. What this means is that this huge wall, including the panes, the frames, and the major steel vertical beams, are simply hanging by the welds at the top of the wall, where it joins the steel roof beams. ALL of this will need to be removed and replaced with an entirely new system. However, the east wall can’t simply be pulled down because the east wall immediately adjacent to the most fossil rich part of the quarry face, with hundreds of bones piled up in a bone jam. So the wall will need to be cut up and removed in sections --- first the glass and frames, then the beams. And that’s where the next difficulty appeared.

It was known that lead paint was almost certainly present on the frames. Fifty years of painting in the Quarry Visitor Center has left a structure with a paint stratigraphy in which the oldest layers are lead based. So lead abatement was planned for in the removal. What was unexpected was that asbestos was in the glazing holding the panes in their frames. That discovery delayed the project as a new abatement plan was developed. Ultimately a crane was brought in and the contractors erected a negative pressure chamber on the basket and dressed in “moon suits” and wearing breathing apparatus, used electric saws to cut away the panes and their frames. At the end of this part of the rehab project, only the vertical steel beams are left, to be removed at a later date. The same removal and safety system will be used to remove the glass on the other walls.

Surprisingly, there is a bright side to all this drama. The complete removal of the east wall ends up providing a solution to the most vexing problem in the QVC project --- how to get the 4 ton crane out of the building. More on that later.

Photos courtesy of Dinosaur National Monument

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