The North Chemical Building at the Water Treatment Plant has a height equivalent to a five story building in which the first two stories house chlorine gas cylinders, vacuum filters, and an electrical room.  The third floor houses lime slaker, and two lime storage hoppers (Hopper Nos. 3 and 4) occupy the top two stories of the building.  The bottom cone-shaped portion of the hoppers is of steel construction supported on reinforced concrete beams at the fifth floor level.  The top section of the hoppers is composed of reinforced concrete walls and top slab.  The USD staff indicate that intrusion of water into Hopper No. 3 caused an expansive reaction of the lime.  Expansion of the lime in Hopper No. 3 caused an outward pressure which caused failure of the south wall of the building.  Additional damage may have occurred but is not visible without a more in-depth inspection.  Observations and preliminary recommendations from Hazen and Sawyer are documented in two letters to USD dated November 22, 2013 and February 11, 2014.  The North Chemical Building feeds lime slurry to Hydrotreator No. 3.  Currently the hoppers at the North Chemical Building as well as Hydrotreator No. 3 are not in operation.  The USD wishes to place Hydrotreator No. 3 in service, thus the rehabilitation of the North Chemical Building is required.  The rehabilitation of the North Chemical Biulding must restore the structural integrity to the original as-designed level such that the lime storage hoppers can be used.