WFF Restoration of MB Electrical Infrastructure SOW- Draft.pdf

Statement of Work for Construction Services RFP No. TBD, Rev. 0

WFF Restoration of Main Base Electrical Infrastructure

Statement of Work

1 Task Order Title: Construction of the WFF Restoration of Main Base Electrical Infrastructure

2 Background & Purpose:

NASA Wallops Flight Facility (WFF), located in Accomack County, Virginia, is undergoing a series of expansions and upgrades to improve the overall safety, reliability, and redundancy of their 12,470 V, 3 Wire medium voltage distribution system on the Main Base. The current 1980's direct burial cable system is past its life expectancy and in need of replacement. In addition to the direct burial cable, many of the existing air switches that make up the 12,470 V medium voltage distribution system on WFF Main Base have surpassed their life expectancy and are a growing concern as they are showing evidence of voltage tracking. Replacement and serviceability of the air switches is an issue as many of the switch parts are obsolete and replacement parts must be cannibalized from salvaged switches. Lastly, two feeder loops will be formed as part of this project. By installing redundant and looped feeds it will allow service personnel to isolate faults and restore power quicker thereby minimizing down time.

3 Scope of Work to be Performed:

This project will be broken up into two phases of construction. Phase 1 construction will consist of the replacement of 30 - 15 kV air switches with 15 kV SF6 gas switches. Also, 9 oil filled low voltage transformers will be replaced. Roughly 75,000 linear feet of the existing medium voltage cable will be replaced with nearly 105,000 linear feet of new 15 kV cable. Approximately 20,000 feet of the new cable will be installed in 4” horizontally bored duct and the rest will utilize existing ducts. Redundant feeders and looped circuits will be created as part of this project to allow for more flexibility and resiliency during power outages and system maintenance (see Appendix C). The existing backbone feeder throughout the Main Base is 15 kV, 4/0 AWG copper with the exception of a few sections of the system. These remaining portions shall be replaced with 4/0 AWG or greater feeders to ensure no overloading of the feeders is caused by the creation of the looped feeds. In order to create the looped circuits the last remaining portion of the old 2400V system that serves the airfield will require upgrading to a 12,470 V, 3-Wire system (see Appendix D). This includes replacing all direct burial cables, sectionalized switches, transformers, and other related equipment that make up the 2400 V system. Contractors will be required to provide testing of all installed equipment and cables as well as provide a system coordination, arc flash, and fault analysis once the equipment selection is finalized.

Phase 2 construction will consist of the replacement of 5 - 15 kV air switches with 15 kV SF6 gas switches. Also, 5 oil filled low voltage transformers will be replaced. Roughly 35,000 linear feet of the existing medium voltage direct burial cable will be replaced with new 15 kV cable in 4” horizontally bored duct. In addition, a looped feeder will be created as part of this project to allow for more flexibility and resiliency during power outages and system maintenance (see Appendix C). The existing backbone feeder throughout the Main Base is 15 kV, 4/0 AWG copper with the exception of a few sections of the system. These remaining portions shall be replaced with 4/0 AWG or greater feeders to ensure no overloading of the feeders is caused by the creation of the looped feeds. Contractors will be required to provide testing of all installed equipment and cables as well as provide a system coordination, arc flash, and fault analysis once the equipment selection is finalized.

DRAFT

4 Description of the Existing Medium Voltage System:

Currently, the power for the WFF Main Base is being served through a line-up of double ended, multi-bus switchgear located at Building N-132. WFF receives power from the local area service provider, A&N Electric Cooperative (ANEC), via two overhead feeds that feed into the N-132 switchgear. From the N- 132 switchgear power is distributed through the Main Base via three primary circuits. A fourth primary circuit connects the 3.1 MW diesel generator, located in Building D-8, to the N-132 switchgear in order to provide back-up power to the circuits designated Circuit 1 & 2. Circuit 3 is backed up by the mobile 1.75 MW generator, located adjacent to Building N-132, and is connected to Circuit 3 via an automated sectionalized switch. The existing backbone feeder throughout the Main Base is 4/0 AWG copper with the exception of a few sections of the system. Radial and load feeds are typically sized smaller and based on the projected load for those feeds. Existing feeders in the core of the campus are typically distributed throughout via concrete encased duct banks. As feeders progress towards the perimeter of the Main Base that are transitioned to either direct burial cable, buried conduit or bored conduit.

The 2,400 volt system, located on the Main Base, is currently served by a 1500 kVA, 12.47 kV/2.4 kV step-down transformer and radial feed that provides power to the air traffic control tower, airfield lighting vault, airfield radar building, airfield operations building, and other minor facilities assets/infrastructure.

Under Phase 1 of this project the 1500 kVA transformer (TR A3-2) serving the 2400 volt system will be removed. All medium voltage cables on the 2400 V system will be replaced and installed in a new conduit system. All 2400 volt primary transformers and air switches will be replaced with 12.47 kV transformers and SF6 gas switches. In addition, in Phase 2 NASA wants to connect the radial feed that currently serves the 2400 volt system with the radial feed that serves the M-Area of the Main Base to create a primary loop feed. See Appendix E for attachments for an excerpt of the one-line and GIS map of the 2400 V system. New distribution infrastructure will be based upon NASA standards for construction of underground distribution facilities and FAA Airport Construction Standards. This system will utilized underground manholes, vaults, handholes, submersible junction bars with 600A dead-break elbow connectors, and painted stainless steel SF6 gas switchgear for pull points to serve existing load.

5 Construction Parameters, Considerations, Materials:

Included with this statement of work is a brief listing of NASA required parameters, considerations, equipment, materials, and preliminary design data summary. The data provided is not inclusive and may change as the project progresses to incorporate alternate design concepts, parameters, equipment, materials, and added aspects of the detailed design. In addition, all work shall meet the minimum code requirements in the current versions of the NESC, NFPA 70 & 70E, the permitting requirements of the Virginia Department of Environmental Quality (DEQ), and the minimum design standards as outlined in UFC 3-550-01 Exterior Electrical Power Distribution.

5.1 Sectionalized Switches – Shall be multi-way, pad-mounted SF6 insulated gas switches with the retrofit enclosure and tank design currently being employed at WFF. The retrofit enclosure is built to fit on most of the existing concrete housekeeping pads utilized at WFF. In addition, the design includes an elevated tank design with rear access doors to allow for more work and conductor clearance in the bottom of the switch. Enclosures, tanks, and bases will be painted stainless steel and mounted atop concrete housekeeping pads unless a manhole/vault is recommended. For switches mounted on new pads provide a spare conduit in the switch for each available spare way and extend it 5 feet out from the switch pad. Specify 600 ampere dead break connectors with 200 ampere interface bushings for each switch way.

5.2 Transformers – Shall be the standard style dead front, three-phase pad-mounted transformers currently being employed at WFF. Transformer must be loop-feed capable with 6 bushings with two-position, oil-immersed, load break switches. Transformer enclosures, tanks, and bases shall be painted stainless steel. Provide bushing-mounted elbow type arresters at the ends of all radials and in normally open locations in loops. For transformers mounted on new pads provide a spare conduit in the high voltage section extending 5 feet out from the transformer pad.

5.3 Junction Cabinets – Shall be above ground enclosed termination points supported by precast concrete ground sleeves anchored by concrete sonatube formed piers. Enclosures will be painted stainless steel.

5.4 Primary Underground Service Conductors – Utilize copper MV-105 133% EPR insulated single conductors with copper tape shield provided with an appropriately sized bare copper ground conductor. The ground conductor shall be tied into the grounding electrode system of the piece of equipment at each end.

5.5 Tag all underground cables in all accessible locations such as in manholes, handholes, junction cabinets, transformers, switches and switchgear. Labels and nomenclature must meet the base utility standards.

5.6 Individually fireproof medium voltage cables in all underground structures.

5.7 Secondary Underground Service Conductors – Utilize stranded XHHW-2 copper conductors sized to the amperage of the transformer secondary. An appropriately sized insulated copper ground conductor shall be provided and tied into the grounding electrode system of the piece of equipment at each end.

5.8 Feeder and Duct Routing – Raceways will be directionally bored 4" or greater red impregnated HDPE conduit with a minimal burial depth of 6'-.0". Contractor shall verify pull tension and jam ratio calculations for the proposed feeder and conduit pulls. Contractor shall propose routes that make use of the existing conduit systems installed during previous projects where possible. When no existing conduit system is in the area of work or the existing conduit system is filled to capacity the A/E shall propose an alternate routing take into consideration natural and manmade existing boundaries and obstacles while providing a reasonably short, direct path to serve both critical loads and non-critical. Other considerations include clearance to roads and other utilities and simplicity of construction which minimizes total project cost. Installation shall be accomplished by directional bore in most cases, with some possible open cuts and hand digging, particularly when other utilities are in the area and around connection points to existing equipment. Install a detectable locator tape above all buried underground conduits. Do not route primary underground service conductors under buildings except as a direct service entrance to a single interior transformer.

5.9 Secondary service conductors will be installed in conduit and may be direct buried.

5.10 Existing conduit systems where conductors will be removed and not replaced are to be capped/plugged at each end and abandoned in place in lieu of being removed.

5.11 Existing direct burial cable to be abandoned in place. At equipment connection points, direct burial cable shall be traced back 10 feet from the piece of equipment, cut, and buried.

5.12 Switch and Junction Support Structure Design – A majority of the existing sectionalized switches on the Main Base are mounted on cast in place concrete housekeeping pads. There are several switches that are mounted on top of buried manholes (vaults) with primary 15 kV junctions located within the manholes. It is proposed that newly required switches be mounted on cast in place concrete pads in most situations. Junction Cabinets will be elevated and mounted on open bottom concrete sleeves, with the junctions located within the pad mounted enclosures.

5.13 Connection to Distribution Loads - Distribution loads will be connected using new and existing SF6 switchgear. Each feeder will require one (1) 600A way with one being normally open. Transformers will be supplied by a 200A switch position.

5.14 Line Protection - Overcurrent protection for the feeders will be provided by circuit breakers at the N-132 substation. Settings will be determined based on studies being done concurrently with this design. Protection beyond the N-132 substation is desired for larger loads and will be provide via fused elbow connectors.

6 Estimated Schedule/Milestones:

1/1/21 – 7/1/22 – Phase 1 Construction (18 month duration)

7/1/22 – 7/1/23 – Phase 2 Construction (12 months duration)

7 NASA Points of Contact:

NASA Contract Specialist – Contracting Officer

Name: Aaron Case

Title: Contract Specialist

Phone: 757-824-1592

Email: aaron.m.case@nasa.gov

NASA Project Manager – Contracting Officer Technical Representative

Name: Stephen Mariner, PE, Title: NASA WFF Facilities Management Division Electrical Engineer

Phone: 757-824-1363

Email: stephen.a.mariner@nasa.gov

APPENDIX A – Direct Burial Cable Routing Map

APPENDIX B – Air Switch Location Map

APPENDIX C – Proposed Feeder Loops Map

APPENDIX D – 2400 V System Map and One-line