Questions.pdf

Questions Relating to Solicitation No. FA3016-18-R-0060

Chiller Replacement, Bldg. 2000, Lackland AFB, TX

1. As-Built drawings with equipment schedules for the AHU’s served by the existing chiller in addition to the electrical, mechanical, and plumbing drawings are needed to provide a comprehensive evaluation for proposal preparation and equipment sizing. Discrepancies in the existing air-cooled chiller characteristics will need to be cross-checked against the As-Built drawings and mechanical schedules. Please provide?

a. Available As-built drawings will be furnished to the contractor after award, before the start of the design.

2. The intent of the project is to match the existing capacity of the chiller and the chilled water pump. The nameplate of the existing chiller is illegible. Please provide the complete existing model and serial number of the existing chiller?

a. For Bidding purposes, use chiller data provided in Item 1.3.2 of the SOW.

3. The characteristics of the existing chiller as stated in the solicitation (flow rate, ambient, and

CHW EWT/LWT) will be higher than the stated capacity of 134.4 Tons. Please confirm the capacity of the chiller?

a. There is a slight discrepancy, however, for bidding purposes, assume 139 tons of AC.

4. Please provide the design/parameters for the AHU’s served by the chiller to verify the required capacity?

a. Refer to Question No.1, available information on AHU’s will be provided after award.

5. Please provide all as-builts drawings (Mechanical, Electrical, Plumbing, Structural, Architectural, etc) available for this area of building 2000.

a. See Item No. 1.

6. Owner to verify where the existing chilled water lines that are connected to this chiller’s system extend to. These are the chilled water lines that are routed over AHU-3D and extend beyond the east wall of the mechanical room. Are these chilled water lines active when the backup chiller becomes active?

a. Ref: Amendment to paragraph 1.3.2 of the SOW. The back-up chiller serves Rm 219F, and AHUs 3A, 3B, 3C and 3D.

7. Owner to confirm what energy code this chiller efficiency will need to adhere to or confirm that this is a replacement in kind and the efficiency is not necessary to meet energy code per exceptions listed in energy code.

a. To be determined during the design phase, assume full compliance with applicable codes.

8. Is an end suction pump the preferred pump type or is a vertical inline pump also acceptable?

9. The vertical inline pump is not acceptable.Is an additional skid adjacent to the chiller which allows for the pump to be installed outside in an enclosure acceptable to the owner?

a. No, keep the existing arrangement.

10. Air cooled chillers require a minimum system volume to provide sufficient capacitance in the system to prevent the chiller from short cycling. We did not see an existing buffer tank to meet this system volume and based on the piping in the mechanical room it did not appear there is currently sufficient volume to meet the current recommendations of 3-5 gallons/ton. Would recommend that this requirement be listed for all parties bidding this project to review and provide a buffer tank as necessary once further information is provided.

a. Ref: paragraph 1.3.2 of the SOW, the contractor is to provide all components necessary to provide a fully functioning system.

11. Confirm whether the existing shot feeder shall also be replaced under this project.

a. Yes, remove and replace the existing shot feeder.

12. Industry standard recommends an air/dirt separator, makeup water valves and expansion tank be provided for closed loop chilled water system. Currently SSA did not see these at the site during the site visit on 07/11/2018. Please confirm whether these should be included in this project. SSA typically recommends these be provided but if cost is an issue then these are not necessary.

a. See Item 10 above.

13. Confirm that this project’s scope is only for the replacement of the chiller, associated exterior piping, associated CHW pump and bypass piping. All CHW piping and controls to switch over from the house CHW to the backup chilled water system downstream of the pump will remain as is.

a. See amendment on the SOW, paragraph 1.3.2.

14. Please identify where asbestos could be located for this project. Is a Hazardous Material Survey required as part of this RFP.

a. There is no asbestos report for the project site. Recent testing by CE Environmental

Section indicates there is no asbestos materials or Hazmat issues in the project site.

However, if any suspect materials are found, the contractor should stop work and call the 502 Environmental Flight for further sampling.

15. Verify that an electrical outage can be taken to all the other equipment served off the MDP or if the new chiller and pump will need to be served from a different electrical panel.

a. It is unlikely that an outage will be required on the entire MDP, however, the contractor to determine existing electrical conditions during the design phase investigations.

16. 1. Paragraph 1.3.2 of the SOW requires the chilled water pump to be replaced. There are no provisions in the existing piping to isolate the backup chilled water pump from the main piping loop serving the air handling units. To remove the pump and connected piping, the main chilled water loop will need to be shut down while the pump is replaced. This outage may be several days. Is this acceptable to the Government?

a. No more than two days, over a weekend or holiday, when the bldg. is Minimally occupied. A temporary chiller for computer rooms maybe required if an outage will affect the entire facility.

17. 2. Paragraph 1.3.2 of the SOW requires the chilled water pump to be replaced. To avoid a lengthy shut down of the main chilled water loop while the back-up pump is being replaced, should the project include the installation of two butterfly cut-off valves in the piping upstream of the backup chilled water pump?

a. Yes

18. 3. There is a bypass with a bypass valve at the end of the main chilled water loop adjacent to the backup chilled water pump. Does the existing DDC system shut the valve when the backup system starts? If not, there will be the possibility of the chilled water backflowing through the bypass back to the inlet of the backup pump during operation and the new backup chiller will not have sufficient water flow.

a. See item 10 above.

19. 4. On what event will the backup chiller and pump be started? Does the existing DDC system already have a control sequence to start the backup pump and chiller or is the backup system started manually?

a. The back-up chiller and pump will automatically start upon failure of the Central Plant.

The back-up system should change over automatically. See amendment to paragraph

1.3.2.

20. 5. The existing chilled water system is being chemically treated by the Government. Will the

Contractor be required to chemically treat the system after the filling the system when the backup chiller and pump are replaced or will the Government furnish and install the chemical treatment?

a. The only treatment needed is a closed loop corrosion inhibitor feed thru shot feeder.

21. 6. If the Contractor is required to chemically treat the chilled water system, can the Government provide the contact information of the chemical treatment company that is currently treating the existing system?

a. Water Treatment is not part of this project.

22. 7. There is a chemical shot feeder behind the backup chilled water pump and it connects into the chilled water piping below the bypass. In this configuration, chemical treatment can only occur when the backup pump is running. Does the government want the chemical shot feeder relocated for access and piped into the main chilled water system?

a. The main loop likely has its own shot feeder (to be verified during design).

23. 8. There is a horizontal expansion tank serving the existing system. Does the Government want the expansion tank and make-up water assembly upgraded as part of this project?

a. To be determine during the design phase.