Fort Loudoun Lock HVAC Rehab, Operations Bldg

The Corps of Engineers has need of a single fixed price construction contract for rehabilitation of the HVAC system in the Operations Building at Fort Loudoun Lock. The operations building at Fort Loudoun houses existing system(s) that do not provide adequate cooling, ventilation, or exhaust. The lack of air being exhausted contributes to the rise in temperature for the building along with the absence of cooling system. There is a lack of fresh air coming into the structure as well which violates ASHRAE 62.1 standards. This project will include the removal of existing exhaust fan systems, ductwork, and other misc. items. The heaters alongside the operations building lock will be left in place as is whether in working condition or not. Also, the mini-split system units that are being used by the project personnel will not be removed by the contractor. These units will remain in place, and they will be removed by the project personnel after the new system has been installed. The newly installed system will consist of one 5-ton packaged heat pump that will service the downstream side of the operations building, and one 6-ton packaged heat pump that will service the upstream side of the operations buildings. Each packaged heat pump will service approximately one half of the operations building, and they will be placed on the roof adjacent to the 3rd floor (El. 832.00) offices. The new system will require new ductwork for supply, return, and exhaust. The supply and return ductwork will be routed from the Roof Top Units (RTU) to the designated rooms to condition. New exhaust ductwork will be routed from the existing exhaust shafts and the upstream women’s toilet to the large existing louver (Mk67N793-5). Exhaust ductwork will be sized by the airflow required by ASHRAE 62.1 2019 Table 6-2 “Minimum Exhaust Rates” (50 cfm per bathroom). Inline exhaust fans will be installed in each of the new ductwork runs in order to have a more balanced system. The exact location of the fans must be at a location which allows ease of accessibility for maintenance. Exhaust fans will also be placed in each bathroom that will turn on when the lights turn on for personal relief. The outdoor fresh air rate must satisfy ASHRAE 62.1 2019 Table 6-1 “Minimum Ventilation Rates in Breathing Zone” (0.06 cfm/ft2), and this will be achieved by adding an economizer to the packaged heat pump. Since we will not be using the upstream louver as a fresh air intake, the contractor will cover the upstream louver without altering the external look of the building. Portions of the existing ductwork that will remain and be used alongside the new system will be so indicated on the contract drawings. Package units and outside ductwork shall be placed in such a way that it maintains the historical appearance of the building. The downstream rooftop has a 32 inch tall parapet wall. The parapet wall has a width of 12 inches, and the top of the railing is 42 inches. Ductwork will run along the wall over the edge of the roof and access the ventilation shaft on both the upstream and downstream units. For the downstream unit, the roof downspouts will have to be relocated towards the landside of the building. The upstream rooftop does not have a parapet wall. As a fall protection system, the contractor will install/construct a horizontal lifeline (HLL) that meets all EM 385-1-1 and OSHA requirements. This HLL will be used by the contractor while installing the packaged unit and ductwork on the upstream roof, and it will be left in place for the future use by the government. Contractor shall also construct a ladder on the upstream landside wall of the building which meets or exceeds EM 385-1-1, ANSI/American Ladder Institute (ALI) A14 series, and OSHA requirements. The ladder shall remain for future use by the Government. The current electrical distribution system in the operations building has limited additional capability; there is only one 208/120V panel in the Motor Control Center (MCC) at elevation 808.0 and it has few remaining spaces. The only other available sources of power are two pairs of heating and lighting 208/120V panels located on elevation 822.33, one pair each for the upstream and downstream ends of the building. Due to the construction of the building and the limited number of existing embedded conduits it would be difficult to route power to each rooftop unit from these locations; therefore new distribution will need to be added. The new distribution panelboard will be located in in the mechanical equipment room. This new main panelboard shall be a 208/120 V three phase, four wire wye distribution. The RTUs shall use 208 V, three phase power while single phase 120 V will be used to power the exhaust fans and fan control devices. Because each RTU requires a disconnecting means to comply with the NEC a sub-panelboard, same electrical characteristics to the main, and motor disconnect shall be located within reasonable distance of each unit. A receptacle is must also be installed for servicing the roof equipment as needed. The enclosure for these exterior panelboards and motor disconnects shall be rated NEMA 4X and shall be grounded as well as the RTUs. An additional sub-panelboard will be added in the storage room to provide power to the control box and convenient power to site personal. As mentioned the 208/120 V three phase power will be needed for the new distribution system. A new transformer of 480/208 V three phase, wye to wye will be installed. The 480 V will be provided through lighting panel near the MCC labeled PNL-RLP-1 as space is available. The transformer will be dry-type and mounted on a stand to prevent damaged that may be caused by possible room flooding. Transformer shall have required capacity to power the new existing system plus an additional reserved capacity for future loads. The wiring and conduit entering and leaving each panel shall be installed as shown in the drawings. Conduit material will differ depending on electrical and temperature characteristics. The conduit used at the transformer shall be Flexible Metal Conduit (FMC) to reduce noise from possible vibrations near the transformer, while the outdoor conduit shall be Rigid Metal Conduit (RMC) used for wet and damp locations. The rest of the interior shall be Electric Metallic Rube (EMT) and all wire shall be copper. Motor disconnects shall be manual lever switches with locks installed to ensure service is done by qualified personal. The fan controls will be will be tuned at necessary dc voltage level to ensure the proper exhaust rate for exhaust fan is selected. A 2 minute delay will added to prevent exhaust fan to run while RTU air handlers are running. The existing lighting and heating panels located in the control room are outdated and shall be replaced, with panels not less than in size then the current existing ones. The new system will be tested with the Duct Air Leakage Test method (DALT) and the Testing and Balancing Procedures (TAB) as per the specifications.

Division 23 -

Heating, Ventilating, and Air Conditioning (HVAC), Instrumentation and Control for HVAC, HVAC Air Distribution, Central HVAC Equipment.