CH2M HILL is supporting cleanup at the Fitzner/Eberhardt Arid Lands Ecology (ALE) Reserve, a National Environmental Research Park on the Hanford Site. ALE Reserve is a 120-square-mile area of native shrub steppe vegetation on the eastern flank of Rattlesnake Mountain. The site has historical significance for the Tribal Nations and was once used as a buffer zone for anti-aircraft defense missions for the U. S. Army. The site was closed to public access in the early 1940s. Challenges associated with the cleanup effort include minimizing damage to the ecosystem while removing material and debris from along the rugged terrain of the mountain.