36C25622R0094 260541 UNDERGROUND ELEC CONSTRUCTION .docx
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- Z2DA--Project #502-19-107 - Replace AHU-104 - Construction - 36C25622R0094 Federal contract opportunity
- Solicitation number
- 502-19-107
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This solicitation package includes specifications for replacing an air handling unit and associated ductwork at a Department of Veterans Affairs medical facility. Key requirements include removing an existing air handling unit and installing a new unit along with new ductwork in Building 7. The solicitation number is 502-19-107 and was issued by the Department of Veterans Affairs Veterans Health Administration Veterans Integrated Service Network 16. Offerors should follow specifications in Section 26 05 41 for underground electrical construction, including installing new ducts, raceways, pull boxes, and connections to form a complete underground electrical system serving the new air handling unit.
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Text version
REPLACE AHU #104 AND DUCTWORK BLDG. 7
DEPARTMENT OF VETERANS AFFAIRS HEALTH CARE SYSTEM-ALEXANDRIA, LA
PROJECT NO.: 502-19-107
SECTION 26 05 41
UNDERGROUND ELECTRICAL CONSTRUCTION
PART 1 GENERAL
1.1 DESCRIPTION
| A. | This section specifies the furnishing, installation, and connection of underground ducts and raceways, and pullboxes to form a complete underground electrical raceway system. |
| B. | The terms “duct” and “conduit” are used interchangeably in this section. |
1.2 RELATED WORK
| A. | Section 07 92 00, JOINT SEALANTS: Sealing of conduit penetrations. |
| B. | Section 26 05 11, REQUIREMENTS FOR ELECTRICAL INSTALLATIONS: Requirements that apply to all sections of Division 26. |
| C. | Section 26 05 26, GROUNDING AND BONDING FOR ELECTRICAL SYSTEMS: Requirements for personnel safety and to provide a low impedance path for possible ground fault currents. |
| D. | Section 31 20 11, EARTH MOVING (SHORT FORM): Trenching, backfill, and compaction. |
1.3 qualITY ASSURANCE
| A. | Quality Assurance shall be in accordance with Paragraph, QUALIFICATIONS (PRODUCTS AND SERVICES) in Section 26 05 11, REQUIREMENTS FOR ELECTRICAL INSTALLATIONS. |
| B. | Coordinate layout and installation of ducts, and pullboxes with final arrangement of other utilities, site grading, and surface features. |
1.4 SUBMITTALS
| A. | Submit in accordance with Paragraph, SUBMITTALS in Section 26 05 11, REQUIREMENTS FOR ELECTRICAL INSTALLATIONS, and the following requirements: |
| 1. | Shop Drawings: |
| a. | Submit sufficient information to demonstrate compliance with drawings and specifications. |
| b. | Submit information on, pullboxes, ducts, and hardware. |
| c. | Proposed deviations from the drawings shall be clearly marked on the submittals. If it is necessary to locate pullboxes, or duct banks at locations other than shown on the drawings, show the proposed locations accurately on scaled site drawings, and submit to the COR for approval prior to construction. |
| 2. | Certifications: Two weeks prior to the final inspection, submit the following. |
| a. | Certification by the manufacturer that the materials conform to the requirements of the drawings and specifications. |
| b. | Certification by the Contractor that the materials have been properly installed, connected, and tested. |
1.5 APPLICABLE PUBLICATIONS
| A. | Publications listed below (including amendments, addenda, revisions, supplements, and errata) form a part of this specification to the extent referenced. Publications are referenced in the text by designation only. |
| B. | American Concrete Institute (ACI): |
| Building Code Requirements for Structural Concrete | |
| 318-14/318M-14 | Building Code Requirements for Structural Concrete & Commentary |
| SP-66-04 | ACI Detailing Manual |
| C. | American National Standards Institute (ANSI): |
| 77-14 | Underground Enclosure Integrity |
| D. | American Society for Testing and Materials (ASTM): |
| C478 REV A-15 | Standard Specification for Precast Reinforced Concrete Manhole Sections |
| C858-10 | Underground Precast Concrete Utility Structures |
| C990-09 | Joints for Concrete Pipe, Manholes and Precast Box Sections Using Preformed Flexible Joint Sealants. |
| E. | National Electrical Manufacturers Association (NEMA): |
| TC 2-13 | Electrical Polyvinyl Chloride (PVC) Conduit |
| TC 3-15 | Polyvinyl Chloride (PVC) Fittings for Use With Rigid PVC Conduit And Tubing |
| TC 6 & 8-13 | Polyvinyl Chloride (PVC) Plastic Utilities Duct For Underground Installations |
| TC 9-04 | Fittings For Polyvinyl Chloride (PVC) Plastic Utilities Duct For Underground Installation |
| F. | National Fire Protection Association (NFPA): |
| 70-17 | National Electrical Code (NEC) |
| 70E-15 | National Electrical Safety Code |
| G. | Underwriters Laboratories, Inc. (UL): |
| 6-07 | Electrical Rigid Metal Conduit-Steel |
| 467-13 | Grounding and Bonding Equipment |
| 651-11 | Schedule 40, 80, Type EB and A Rigid PVC Conduit and Fittings |
| 651A-11 | Schedule 40 and 80 High Density Polyethylene (HDPE) Conduit |
PART 2 PRODUCTS
2.1 pullboxes
| A. | General: Size as indicated on the drawings. Provide pullboxes with weatherproof, non-skid covers with recessed hook eyes, secured with corrosion- and tamper-resistant hardware. Cover material shall be identical to pullbox material. Covers shall have molded lettering, ELECTRIC or SIGNAL as applicable. Pullboxes shall comply with the requirements of ANSI 77 Tier 5loading. Provide pulling irons, 22 mm (0.875 inch) diameter galvanized steel bar with exposed triangular-shaped opening. |
| B. | Polymer Concrete Pullboxes: Shall be molded of sand, aggregate, and polymer resin, and reinforced with steel, fiberglass, or both. Pullbox shall have open bottom. |
| C. | Fiberglass Pullboxes: Shall be sheet-molded, fiberglass-reinforced, polyester resin enclosure joined to polymer concrete top ring or frame. |
| D. | Concrete Pullboxes: Shall be monolithically poured reinforced concrete. |
2.2 Ducts
| A. | Number and sizes shall be as shown on the drawings. |
| B. | Ducts (concrete-encased): |
| 1. | Plastic Duct: |
| a. | UL 651 and 651A Schedule 40 PVC conduit. |
| b. | Duct shall be suitable for use with 90˚ C (194˚ F) rated conductors. |
| 2. | Conduit Spacers: Prefabricated plastic. |
| C. | Ducts (direct-burial): |
| 1. | Plastic duct: |
| a. | UL 651, 651A, and 651B, Schedule 80 PVC or HDPE conduit. |
| b. | Duct shall be suitable for use with 75˚ C (167˚ F) rated conductors. |
| 2. | Rigid metal conduit: UL 6 and NEMA RN1 galvanized rigid metal, half-lap wrapped with 10 mil PVC tape. |
2.3 Grounding
A. Ground Rods and Ground Wire: Per Section 26 05 26, GROUNDING AND BONDING FOR ELECTRICAL SYSTEMS.
2.4 WARNING Tape
A. 4-mil polyethylene 75 mm (3 inches) wide detectable tape, red with black letters, imprinted with “CAUTION - BURIED ELECTRIC CABLE BELOW” or similar.
2.5 PULL Rope for spare ducts
A. Plastic with 890 N (200 lb) minimum tensile strength.
PART 3 EXECUTION
3.1 pullbox INSTALLATION
| A. | Assembly and installation shall be per the requirements of the manufacturer. |
| 1. | Install pullboxes level and plumb. |
| 2. | Units shall be installed on a 300 mm (12 inches) thick level bed of 90% compacted granular fill, wellgraded from the 25 mm (1 inch) sieve to the No. 4 sieve. Granular fill shall be compacted with a minimum of four passes with a plate compactor. |
| B. | Access: Ensure the top of frames and covers are flush with finished grade. |
3.2 TRENCHING
| A. | Refer to Section 31 20 11 EARTH MOVING (SHORT FORM) for trenching, backfilling, and compaction. |
| A. | Before performing trenching work at existing facilities, a Ground Penetrating Radar Survey shall be carefully performed by a certified technician to reveal all existing underground ducts, conduits, cables, and other utility systems. |
| B. | Work with extreme care near existing ducts, conduits, and other utilities to avoid damaging them. |
| C. | Cut the trenches neatly and uniformly. |
| D. | For Concrete-Encased Ducts: |
| 1. | After excavation of the trench, stakes shall be driven in the bottom of the trench at 1.2 M (4 feet) intervals to establish the grade and route of the duct bank. |
| 2. | Pitch the trenches uniformly toward manholes or both ways from high points between manholes for the required duct line drainage. Avoid pitching the ducts toward buildings wherever possible. |
| 3. | The walls of the trench may be used to form the side walls of the duct bank, provided that the soil is selfsupporting and that the concrete envelope can be poured without soil inclusions. Forms are required where the soil is not selfsupporting. |
| 4. | After the concrete-encased duct has sufficiently cured, the trench shall be backfilled to grade with earth, and appropriate warning tape installed. |
| E. | Individual conduits to be installed under existing paved areas and roads that cannot be disturbed shall be jacked into place using rigid metal conduit, or bored using plastic utilities duct or PVC conduit, as approved by the /COR. |
3.3 DUCT INSTALLATION
| A. | General Requirements: |
| 1. | Ducts shall be in accordance with the NEC, as shown on the drawings, and as specified. |
| 2. | Join and terminate ducts with fittings recommended by the manufacturer. |
| 3. | Slope ducts to drain towards manholes and pullboxes, and away from building and equipment entrances. Pitch not less than 100 mm (4 inches) in 30 M (100 feet). |
| 4. | Underground conduit stubups and sweeps to equipment inside of buildings shall be galvanized rigid metal conduit half-lap wrapped with PVC tape, and shall extend a minimum of 1.5 M (5 feet) outside the building foundation. Tops of conduits below building slab shall be minimum 610 mm (24 inches) below bottom of slab. |
| 5. | Stubups and sweeps to equipment mounted on outdoor concrete slabs shall be galvanized rigid metal conduit half-lap wrapped with PVC tape, and shall extend a minimum of 1.5 M (5 feet) away from the edge of slab. |
| 6. | Install insulated grounding bushings on the conduit terminations. |
| 7. | Radius for sweeps shall be sufficient to accomplish pulls without damage. Minimum radius shall be six times conduit diameter. |
| 8. | All multiple conduit runs shall have conduit spacers. Spacers shall securely support and maintain uniform spacing of the duct assembly a minimum of 75 mm (3 inches) above the bottom of the trench during the concrete pour. Spacer spacing shall not exceed 1.5 M (5 feet). Secure spacers to ducts and earth to prevent floating during concrete pour. Provide nonferrous tie wires to prevent displacement of the ducts during concrete pour. Tie wires shall not act as substitute for spacers. |
| 9. | Duct lines shall be installed no less than 300 mm (12 inches) from other utility systems, such as water, sewer, chilled water. |
| 10. | Clearances between individual ducts: |
| a. | For similar services, not less than 75 mm (3 inches). |
| b. | For power and signal services, not less than 150 mm (6 inches). |
| 11. | Duct lines shall terminate at window openings in manhole walls as shown on the drawings. All ducts shall be fitted with end bells. |
| 12. | Couple the ducts with proper couplings. Stagger couplings in rows and layers to ensure maximum strength and rigidity of the duct bank. |
| 13. | Keep ducts clean of earth, sand, or gravel, and seal with tapered plugs upon completion of each portion of the work. |
| 14. | Spare Ducts: Where spare ducts are shown, they shall have a nylon pull rope installed. They shall be capped at each end and labeled as to location of the other end. |
| 15. | Duct Identification: Place continuous strip of warning tape approximately 300 mm (12 inches) above ducts before backfilling trenches. Warning tape shall be preprinted with proper identification. |
| 16. | Duct Sealing: Seal ducts, including spare ducts, at building entrances and at outdoor terminations for equipment, with a suitable non-hardening compound to prevent the entrance of foreign objects and material, moisture, and gases. |
| 17. | Use plastic ties to secure cables to insulators on cable arms. Use minimum two ties per cable per insulator. |
| B. | Concrete-Encased Ducts: |
| 1. | Install concrete-encased ducts for medium-voltage systems, low-voltage systems, and signal systems, unless otherwise shown on the drawings. |
| 2. | Duct banks shall be single or multiple duct assemblies encased in concrete. Ducts shall be uniform in size and material throughout the installation. |
| 3. | Tops of concrete-encased ducts shall be: |
| a. | Not less than 600 mm (24 inches) and not less than shown on the drawings, below finished grade. |
| b. | Not less than 750 mm (30 inches) and not less than shown on the drawings, below roads and other paved surfaces. |
| c. | Additional burial depth shall be required in order to accomplish NEC-required minimum bend radius of ducts. |
| d. | Conduits crossing under grade slab construction joints shall be installed a minimum of 1.2 M (4 feet) below slab. |
| 4. | Extend the concrete envelope encasing the ducts not less than 75 mm (3 inches) beyond the outside walls of the outer ducts. |
| 5. | Within 3 M (10 feet} of building penetrations, install reinforcing steel bars at the top and bottom of each concrete envelope to provide protection against vertical shearing. |
| 6. | Install reinforcing steel bars at the top and bottom of each concrete envelope of all ducts underneath roadways and parking areas. |
| 7. | Where new ducts and concrete envelopes are to be joined to existing manholes, pullboxes, ducts, and concrete envelopes, make the joints with the proper fittings and fabricate the concrete envelopes to ensure smooth durable transitions. |
| 8. | Duct joints in concrete may be placed side by side horizontally, but shall be staggered at least 150 mm (6 inches) vertically. |
| 9. | Pour each run of concrete envelope between manholes or other terminations in one continuous pour. If more than one pour is necessary, terminate each pour in a vertical plane and install 19 mm (0.75 inch) reinforcing rod dowels extending 450 mm (18 inches) into concrete on both sides of joint near corners of envelope. |
| 10. | Pour concrete so that open spaces are uniformly filled. Do not agitate with power equipment unless approved by COR. |
| C. | Direct-Burial Ducts: |
| 1. | Install direct-burial ducts only where shown on the drawings. Provide direct-burial ducts only for low-voltage power and lighting branch circuits. |
| 2. | Tops of ducts shall be: |
| a. | Not less than 600 mm (24 inches) and not less than shown on the drawings, below finished grade. |
| b. | Not less than 750 mm (30 inches) and not less than shown on the drawings, below roads and other paved surfaces. |
| c. | Additional burial depth shall be required in order to accomplish NEC-required minimum bend radius of ducts. |
| 3. | Do not kink the ducts. Compaction shall not deform the ducts. |
| F. | Connections to Existing Ducts: Where connections to existing ducts are indicated, excavate around the ducts as necessary. Cut off the ducts and remove loose concrete from inside before installing new ducts. Provide a reinforced-concrete collar, poured monolithically with the new ducts, to take the shear at the joint of the duct banks. |
| G. | Partially-Completed Ducts: During construction, wherever a construction joint is necessary in a duct bank, prevent debris such as mud and dirt from entering ducts by providing suitable plugs. Fit concrete envelope of a partially completed ducts with reinforcing steel extending a minimum of 600 mm (2 feet) back into the envelope and a minimum of 600 mm (2 feet) beyond the end of the envelope. Provide one No. 4 bar in each corner, 75 mm (3 inches) from the edge of the envelope. Secure corner bars with two No. 3 ties, spaced approximately 300 mm (12 inches) apart. Restrain reinforcing assembly from moving during pouring of concrete. |
3.4 acceptance checks and tests
| A. | Duct Testing and Cleaning: |
| 1. | Upon completion of the duct installation, a standard flexible mandrel shall be pulled through each duct to loosen particles of earth, sand, or foreign material left in the duct, and to test for out-of-round conditions. |
| 2. | The mandrel shall be not less than 300 mm (12 inches) long, and shall have a diameter not less than 13 mm (0.5 inch) less than the inside diameter of the duct. A brush with stiff bristles shall then be pulled through each duct to remove the loosened particles. The diameter of the brush shall be the same as, or slightly larger than, the diameter of the duct. |
| 3. | If testing reveals obstructions or out-of-round conditions, the Contractor shall replace affected section(s) of duct and retest to the satisfaction of the COR. |
| 4. | Mandrel pulls shall be witnessed by the COR. |
---END---
26 05 41 - 11
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