In 2016 Limbach Mid-Atlantic won a design build contract to repair aging air handlers at the Walter Reed Army Institute of Research in Silver Spring, Maryland. The original award or CLIN (Contract Line Item Number) was to repair/replace (2) air handling units with an additional CLIN of (8) air handling units to follow. Because the facility being used primarily for animal research, it was essential that the design and sequencing of work minimized impacts and shutdowns. LEDS design drawings were sequenced to properly identify the scope of work at each phase of the project in an effort to support the construction team during the project. Furthermore, (4) temporary air handlers were designed and built to minimize impacts and maintain research spaces served by the air handler in construction.
The air handlers to be repaired were large, built-in-place air handlers. The first air handlers to be worked on were the largest at the facility and included AHU-1 (144,000 cfm) and AHU-2 (106,000 cfm). Repair/replacement of the air handlers consisted of replacing all internal components including fans, coils, humidifiers, air to air heat exchangers, filter banks, and dampers. Furthermore, a complete overhaul of the unit was accomplished through new access doors, internal and external casing repair and painting, and a unique redesign and installation of a dividing wall within the units. This redesign incorporating the center dividing wall helped facilitate construction and minimize downtime as well as ultimately provide the facility with (2) full stand alone air handlers in the existing single air handler footprint. The center wall design was further applied to other air handlers that provided the facility with (15) stand alone air handlers where originally there were (10).
Also, included in the design build contract was to redesign (5) failed steam generator installations. Previous incorrect installations had caused the equipment to fail prematurely, after roughly five years. LEDS identified the problem with the existing installation, protested the direction for a similar replacement, and took the necessary measures to redesign and correct the previous installation with a corrected new design and installation. This change required the addition of new equipment for which Limbach received an additional scope modification once the facility and US Army Corp of Engineers agreed to and confirmed the corrected design. The corrected design included new deaerator tanks, steam generators, and automatic condensate pump traps.
Further work was awarded to the design and construction team based on the success of these projects. A scope modification was added to the contract to replace (43) fans associated with the repaired/replaced air handling units and some animal laboratory spaces. The government and facility opted to award the scope modification to the existing contract and team rather than putting it out on the street for bid.
While the project is still ongoing, it has been quite successful to date. The first (2) air handlers and (1) steam generator system are complete and in operation. The second CLIN of air handler work is currently in construction and design has just kicked off for the second CLIN of fan replacement work.