Somehow the cache for lter_ units in my site was empty.  In looking at the MySQL database units-option:en and units:scope=2 were empty arrays.  This cache is created from the deims custom module lter_unit. Specifically in the lib/LterUnitHelper.php

This a drupal_static(__FUNCTION__) .  There is not a way for the cache to expire and get reloaded.  I add the following code to check if the cache data is empty and reload the database if it is.

      $cache = cache_get($cid, 'cache_lter_unit');
      if (!empty($cache->data)

I will make a patch file and post it later.

I would also like to have the option of take my own file of units since this is only the scope=2 units.

Jim L