S06 36C24624B0008-A00005 Attachment I - Phasing - Sequencing of Works.pdf
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- Attached to
- N045--Replace and Upgrade Chilled Water System
- Solicitation number
- 36C24624B0008
About this file
This document appears to be an attachment outlining the proposed sequence of work for the "Replace and Upgrade Chilled Water System" contract opportunity at the Charles George VA Medical Center.
The key details are:
- The work will be executed in multiple phases, including installing a new 14" chilled water supply/return main, installing new branch lines to serve various HVAC equipment, and replacing the main pipes from the chiller plant to the secondary pumps in Building 47. This will require several short-term and longer shutdowns of the chilled water system to tie-in the new piping.
- The contractor will have 20-30 days to complete each section of the work in the East, North-West, South-East, and South-West areas of the 1st and 3rd floors before turning over those areas to the VA.
- The work is expected to be performed from December 1 to March 1 when cooling demand is lowest, with short shutdowns not exceeding 8 hours and major shutdowns not exceeding 20 working days.
- The contract also includes control system updates, testing, adjusting, balancing, and commissioning of the entire upgraded chilled water system.
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Text version
Replace and Upgrade Chilled Water System Charles George VA Medical Center
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PROPOSED SEQUENCE OF WORK (SOW)
1. Installation of the 14ӯ main
a. Install new 14” Ø CHWS/R main in the crawlspace in parallel with the existing 12”Ø CHWS/R main.
b. Provide multiple branches, isolation valves and circuit setters along the main as indicated in the drawings.
c. Cross connect the 14ӯ main to the existing 12ӯ with isolation valves to allow the existing main serving the new one.
2. Installation of branch 3 (serving the small AC in crawl space and H&V on first floor)
a. Install new branch 3 - 4ӯ in parallel with the existing one and connect the new main at the previous installed Tee connections.
b. Small AC in crawl space and H&V on first floor do not need to be shut down during tie-in, but they will lose some short-term mechanical cooling.
3. Installation of branch serving the AC-11 and MRI.
a. Provide back-up cooling for MRI. MRI will continue operating during construction.
b. Install new branch 4ӯ and connect the existing 10ӯ main serving ADA.
c. AC-11 does not need to be shut down during replacement of risers and tie-in. But it will lose some short-term mechanical cooling.
d. Require short term shutdown of MRI for tie-in.
4. Installation of branch 4 (serves the AC-8)
a. Install new branch 4 - 4ӯ in parallel with the existing one and connect the new main at the previous installed Tee connections.
b. Connect the new branch 4 to existing pipe at the bottom of the riser.
c. AC-8 does not need to be shut down, but it will lose some short-term mechanical cooling.
5. Installation of branch 5 (Serving multiple FCUs on third floor of East Tower)
a. Install new branch 5 Р2-1/2ӯ in parallel with the existing one and connect the new main at the previous installed Tee connections.
b. Install branch riser in the shaft from crawl space to third floor.
c. Install two branches with isolation valves on first floor and connect the risers.
d. Replace distribution piping and connect to existing FCUs in east area of the first floor. Contractor shall have 20 days to complete east area and turn over to the VA.
e. After finishing east area, the contractor shall move on to north-west area of the first floor. Contractor shall have 20 days to complete north-west area and turn over to the VA.
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f. Install two branches with isolation valves on third floor and connect the risers.
g. Replace distribution piping and connect to existing FCUs in south-east area of the third floor. Contractor shall have 20 days to complete south-east area and turn over to the VA.
h. After finishing south-east area, the contractor shall move on to north-west area of the third floor. Contractor shall have 20 days to complete north-west area and turn over to the VA.
6. Installation of branch 6 (serves the AC-7A&B)
a. Re-connect the existing branch 6 to previous installed branch on the new main.
b. AC-7A&B do not need to be shut down, but they will lose some short-term mechanical cooling.
7. Installation of branch 7 (Serving multiple FCUs on third floor of West Tower)
a. Install new branch 7 Р2ӯ in parallel with the existing one and connect the new main at the previous installed Tee connections.
b. Install branch riser in the shaft from crawl space to third floor.
c. Install two branches with isolation valves and on third floor and connect the risers.
d. Replace distribution piping and connect to existing FCUs in south-west area of the third floor. Contractor shall have 20 days to complete south-west area and turn over to the VA.
e. After finishing south-east area, contractor shall move on to north-east area of the third floor. Contractor shall have 20 days to complete north-east area and turn over to the VA.
8. Installation of branch 8 (Serving SICU AHU, Pharmacy AHU, multiple FCUs on fourth and fifth floor of South Tower and multiple AHUs in Penthouse and roof)
a. Install new branch 8 Р8ӯ at the end of the new 14ӯ main.
b. Install branch riser in the new chase (soil utility room) up to penthouse.
c. Install sub-branch 8.1 Р4ӯ with isolation valves on second floor.
i. Connect sub-branch 8.1 to SICU-AHU and PHARMACY AHU.
ii. SICU-AHU and PHARMACY AHU do not need to shut down. They do not lose mechanical cooling as they are backed up by air-cooled chillers.
iii. Remove existing pipe from SICU AHU back to penthouse
d. Install sub-branch 8.2 Р4ӯ with isolation valves on fourth floor.
i. Install distribution piping on fourth floor to service both fourth-floor and fifth-floor
FCUs.
ii. The contractor shall start the distribution main in east area and branches to
FCUs serving east side of fourth and fifth floor.
iii. At the end of new main segment, provide cross connect the existing main to allow new main serves the existing one.
iv. Remove existing main and branches in this area.
v. Contractor shall have 30 days to complete east area and turn over to the VA.
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vi. After finishing east area, contractor shall move on to south area and turn over to the VA after 30 days.
vii. After finishing south area, contractor shall move on to west area and turn over to the VA after 30 days.
e. Install branch 8 Р8ӯ with isolation valves in the penthouse in parallel with the existing distribution main in the penthouse.
f. Provide multiple branches with isolation valves as indicated on the drawings.
g. Connect all branches to AHUs in the penthouse and high roof as indicated on the drawings.
h. All AHUs do not need to be shutdown, but they will lose short-term mechanical cooling during tie-in, except MICU AHU as it has back up air-cooled chiller.
9. Removal of all existing piping and risers.
After the main, risers and branches are installed, contractor shall remove existing ones.
Some existing branches that may have isolation valves at main can be removed right after the new one are installed without effecting any downstream equipment. Contractor shall verify in the filed
10. Replace the main pipes from chiller plant to the secondary pumps in building in
Building 47.
After the main, risers and branches are installed and existing ones are removed, contractor shall replace the main pipes from chiller plant to the secondary pumps in building in Building 47.
Since there is no room available for the new pipes to be installed in parallel with the existing one, and the secondary pumps need to be shut down for connection. this task shall require multiple minor and major shutdowns of the entire chilled water system in building 47 and short term shutdown of ACA.
Contractor shall commence this task during the winter, from December 1 to March 1 when the cooling demand is minimum. Short term shutdown shall not exceed 8 hours/each. Major shutdown shall not exceed 20 working/each.
If the construction schedule does not allow, contractor shall do it in the next winter.
All shutdowns shall be reviewed and approved by the COR in advance.
a. All piping shall be fabricated on site and ready to be installed.
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b. Provide shut term shutdown of the entire chiller plant for connection of the new 14ӯ main (serving B47 ) to the existing main headers in chiller plant.
c. Provide isolation valves on new 14ӯ pipes so the chiller plant can be turned back on to serve ACA while work in Building 47 is being done.
d. Provide short term shutdown of Building 57 secondary pumps to install temporary flexible hoses from previous installed 14ӯ pipes to existing system as indicated on the drawings. These hoses will allow replacement of existing section of 12ӯ from chiller plant and B47 secondary pumps without shutdown of chilled water system.
e. Provide major shutdown of building 47 chilled water system to replace the rest of piping of secondary chilled water pumps system, connect to branch 1 & 2.
f. After all piping are installed, remove flexible hoses.
g. Refill the system, bleed air out of the system and turn the system back on.
11. Control, TAB and commissioning.
a. Update control system according to the contract documents.
b. Testing, adjusting and balancing the whole system according to the contract documents.
c. Commissioning the whole system according to the contract documents.
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