S02 SOW - Retro-Commissioning Mech Corrections Construction 595-18-101_Rev1.docx

STATEMENT OF WORK

Retro-Commissioning Mechanical Corrections Project #595-18-101

In general, work shall include all labor, material, equipment and supervision to perform the required mechanical and electrical construction work as shown on the contract drawings and in the specifications. The bid item includes the following:

Replacement of AC-9-1: This cooling-only air handling unit (AHU) is positioned at high level in the Penthouse of Building 1 and cools the elevator machinery. The unit shall be replaced in kind and a new duct main shall be installed. All ductwork branches shall remain unchanged, as practical. New AHU suspension structure and a new hoist hook shall be installed in the Penthouse. The existing Chilled Water (CHW) piping shall be fitted with manual valves allowing AC-9-1 to be isolated without inhibiting the operations of the adjacent AHU. Part of the (CHW) piping shall be relocated so that it does not pass over the top of an existing electrical cabinet. The thermostat shall be relocated from the exterior wall to the column near the elevator machine room.

Replacement of AC-1-24: The existing AHU serving the Gym in Building 24 is positioned at high level and shall be removed entirely, including all supply air ductwork. A new AHU shall be installed in the store room, which shall be repurposed to serve as a mechanical room. The new AHU shall include CHW cooling and steam heating coils, including condensate pump. A mixed air system shall be incorporated, including a return fan at high level. New exhaust hardware shall be included. Ductsox shall be used for supply air, which is positioned at high level above the Gym space.

Replacement of ERU-1-22: The existing energy recovery unit (ERU) positioned on the flat roof of Building 22 shall be replaced in kind. This shall include the installation of occupancy sensors within the corridors at all three floors in Building 22, which allow energy-conservation control sequences to be implemented within the Building. The entire ventilation system within Building 22 shall be balanced upon the completion of a separate renovation project at the Second Floor of the Building. The existing toilet vent pipe shall be re-routed above roof level.

Geothermal Temperature Sensor Corrections: The four energy recovery units in Buildings 34, 35 and 36 are each fitted with four temperature sensors which are not operating correctly. All 16 temperature sensors shall be re-calibrated and the Building Automation System (BAS) reviewed to ensure that they are operating correctly. Any temperature sensors which are identified as not operating correctly shall be replaced in kind.

Geothermal ERU Control Sequence Corrections: The control sequences for all four energy recovery units in Buildings 34, 35 and 36 shall be updated as follows:

• Cooling mode – Supply air (SA) discharge temperature 55°F/48°F (Dry Bulb/Wet Bulb)

• Heating Mode – SA discharge temperature 63°F (DB)

Geothermal Heat Pump Control Sequence and Valve Corrections: A total of 16 valves in the geothermal mechanical room in Building 35 shall be replaced with eight, three-way valves with automatic actuators, which are linked to the BAS. The control sequences for the water-to-water heat pumps shall be modified to allow all four units to operate in heating or cooling mode by operating the eight, three-way actuated valves.

Cross-Connections on ERU-1S, -2S and -1P: The flex cross-connections between the exhaust duct and the outside air duct for all three energy recovery units shall be removed and all openings in the ductwork shall be repaired. The ducts shall undergo leak testing.

Cross-Connection on ERU-1C: The flex cross-connection between the exhaust duct and the outside air duct for this energy recovery unit shall be removed and replaced with a new rigid duct and a balancing damper. Further, the exhaust from several toilets and store rooms at the ground and first floors shall be rerouted and served by a dedicated new exhaust fan and duct run. The exhaust and return systems shall be fully balanced, and the ducts shall undergo leak testing.

Humidity Sensor Corrections: A total of 70 new humidity and temperature sensors shall be installed throughout Buildings 34, 35 and 36 in place of existing thermostats. These humidity and temperature sensors shall be linked to the BAS. The control sequences for the existing chilled beams throughout these buildings shall be modified so that the chilled water supply to the chilled beams is always at least two degrees Fahrenheit (°F) greater than the dew point within the room.

Geothermal ERU Discharge Static Pressure Corrections: A total of four supply fans in the four energy recovery units in Buildings 34, 35 and 36 shall be replaced with fans which are capable of maintaining higher supply air static pressure at the same airflow rate.

ERU Design Improvements: A total of four new direct expansion (DX) condensing units shall be mounted outside Buildings 34, 35 and 36, which shall provide supplemental cooling within the energy recovery units. The existing hot gas reheat coils shall be relocated outside the ERUs and new supplemental cooling coils shall be positioned within the ERUs. A new temperature sensor shall be located downstream of the relocated hot gas reheat coils in each ERU (i.e. four new temperature sensors shall be provided). The Contractor shall also arrange for the heat pumps serving each ERU to be serviced by a manufacturer-certified technician, at any time during the construction period.

BAS Improvements: AC-4-1 shall have a discharge air temperature setpoint reset implemented based on outside air conditions and satisfying all zone cooling requirements. A total of 13 AHUs shall have a static pressure setpoint reset implemented based on the variable air volume (VAV) damper position. Eight AHUs shall have their variable frequency drive (VFD) scaling and drive settings corrected so that field and BAS values are accurate. A factory representative shall work alongside the controls contractor to reprogram the VFDs. AC-3-17 exhaust fan interlock programming shall be rectified to correct an error which allows the exhaust fan to continue running upon a hardwired safety trip of the unit.

Pneumatic Control Upgrades: The existing pneumatic valves for AC-3-18 and AC-4-18 in Building 18 shall be replaced with new direct digital control (DDC) valves which shall be tied into the existing BAS. The existing damper and valve pneumatic actuators shall be replaced with new electric actuators, removing the electric-to-pneumatic transducers, and re-program the unit controller to provide full DDC control. Removal of all existing pneumatic tubing associated with both units and the installation of new control wiring between the actuators and transducers is also included.

Mechanical Improvements: The outside air damper linkage for AC-2-1 in Building 1 shall be repaired. The energy recovery wheel for AC-3-1 in Building 1 is in a deteriorating condition. The energy recovery wheel shall be replaced in kind. Building 136 currently has staged electric heating for most of the VAV terminal units. The electric heating shall be switched from the existing staged electric heat to silicon-controlled rectifier (SCR) electric heating.

Insulation Repairs: Damaged or missing insulation was noted for heating and cooling piping, and for air ducts in different areas of Buildings 1, 18, 22, 34, 36 and 102. All damaged or missing insulation noted shall be reinsulated.

Sensor Corrections: The high static safety sensor switch for AC-3-1 shall be replaced. The discharge air humidity sensor and the mixed air temperature sensor for AC-14-1 shall be replaced in kind.

Chilled Water System Testing, Adjusting, and Balancing (TAB): Testing, Adjusting, and Balancing of the entire campus secondary Chilled Water System loop. Results of the TAB process shall be submitted to the Contracting Officer’s Representative (COR) and Architect/Engineer (AE).

Chilled Water System Upgrades: Existing flow meters for chilled water in Buildings 1, 2, 10, 17, 18, 19, 22, 23 and 104 shall be replaced. Flow meters shall be installed on the primary and secondary chilled water piping for Building 136. Existing temperature sensors for chilled water in Buildings 1 and 19 shall be replaced. New Differential Pressure sensors shall be installed in Buildings 1, 18, 19, and 101, and linked to the BAS for control purposes. New circuit setters shall also be installed in Buildings 1, 24, 104, and 136. Testing and Balancing shall be performed on all primary and secondary chilled water flows for the campus, including but not limited to pumps and circuit setters.

Chilled Water System – Bypass Line Modification: There are currently two bypass lines between primary and secondary loop in chilled water system in Buildings 1, 2, 17, 28, 29, 22, 23, 24, 104, and 136. First bypass has a check valve, second bypass has a check valve and a three-way automatic control valve. First bypass line shall be removed entirely. Check valve and three-way automatic control valve on second bypass line shall be removed. Provide all necessary piping and fitting to reconnect bypass line 2. All removed equipment shall be turned over to the Lebanon VA Medical Center (LVAMC) for future use. Rebalance the primary chilled water flow required for each building base on TAB result.

Chilled Water System – New Secondary Loop: Building 106 is currently connected directly to the primary chilled water loop. Provide two new pumps, two new flow meters, two three-way automatic control valves, a new differential pressure sensor, a new circuit setter, and necessary piping and fittings to create a new secondary bypass loop.

The Contractor shall assume responsibility for all temporary measures adopted during the construction period, to maintain operation of the LVAMC Lebanon VA Hospital and buildings. This shall include but not be limited to temporary heating/cooling/ventilation, coordinating with the COR to relocate personnel and/or ensuring that adequate facilities are provided, where deemed necessary.

The Contractor is responsible to verify the location of all utilities, and other buried or obscured lines (electrical, hydronic, plumbing, etc.) that may be exposed or could be impacted by the work and are within and adjacent to any demolition work. The Contractor shall enlist the assistance of the COR or appointed facility personnel to obtain their opinion as to the locations of such items that may exist within any and all construction areas and that may or may not be presented in the contract documents.

Mobilization/Demobilization: The bid item shall include but not be limited to all work related to moving personnel and equipment to the site, establish temporary access, install staging areas and installing project signs.

Traffic Management: This bid item shall include but not be limited to all work relating to maintaining traffic during construction, including the preparation of traffic management plans, furnishing, installing and maintaining traffic controls (signs, barriers, etc.) and the removal of all traffic controls at the completion of the work, as necessary.

Confined Spaces: All contractors shall be Occupational Safety and Health Administration (OSHA) trained and provide all required safety equipment and monitors for confined space entry.

1. All contractors entering any confined space shall request hot work and confined space permits from the LVAMC VA facility.

2. Contractors shall provide the required OSHA ventilation rates when working in any areas considered confined spaces. All confined spaces shall be purged with ventilation air for 30 minutes before contractor entry.

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