We have underground collection storage at the Folger Library, built in the early 1980s, and it has its good and bad points.

Good:
-- low light levels can be maintained
-- outside climate influences are minimal because it is completely underground (i.e. insulated on all sides by dirt)
-- dedicated air handler unit with back-up generator means, in theory, it could be used if we have to "shelter in place" because of outside disaster (we're a block from the U.S. Capitol, and diagonally across the street from the Supreme Court; since 9/11 we have started keeping emergency food, water, blankets and porta-potties as part of our disaster supplies)
-- sump pumps and a drainage ditch down the middle of the floor mean that if water does come cascading in it will get pumped out again (the floors were supposed to be slightly angled so that water would flow to the drain, but the wall seepage always just puddled near the wall. So much for that plan).

Bad:
-- inadequate (non-existant?) drainage field surrounding the concrete meant that heavy rainwater and groundwater seeped in instead of percolating through the drainage field on its way down to bedrock (the surrounding earth was tight-packed, so the water took the path of least resistance: the concrete). Luckily, the air flow down there was excellent, so despite the periodic wet walls and puddles, we never had a mold problem. A book was damaged (but saved) when its paper call number flag drooped and touched the wall, wicking water into the book. To guard against that happening again, all books were moved so that they were at least a foot from the wall instead of a few inches (there went the growth space!). 
-- blocked drain by an outside door caused water to back up into the building and run down inside walls where no one had anticipated a water problem (guards patrol 24-7 so the problem was caught in time and we moved collections).

Two years ago we were finally able to dig down and replace the drainage field, and haven't had a water problem since.  

Ideally, we would have had an underground collection storage area like the one I just toured at the University of Virginia. Their new Special Collections Library is entirely underground, but instead of having a drainage field and single concrete wall like we do, they have (from the outside in) a drainage field, then a concrete wall, then a corridor (containing pipes and wiring in its ceiling) and *then* the wall for the collections area. Their collections are essentially in a box inside a box.

If you do go ahead with the underground storage area, and don't have the space for the double-hull construction like at UVa, then make absolutely certain your air handling system and air flow design are up to the task. When we put in compact shelving, we insisted on perforated sides to maintain air flow, and cut back on capacity in order to maintain a central aisle for even air flow. 

Best wishes,

  Erin.

--------------------------------------------------
Erin C. Blake, Ph.D.  
Curator of Art & Special Collections  
Folger Shakespeare Library  
201 E. Capitol St. SE  
Washington, DC 20003-1094  
office tel. (202) 675-0323  
fax: (202) 675-0328  
e-mail: [log in to unmask]  
www.folger.edu

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