Okaloosa County BOCC — February 18, 2014 — Underground Electric Manhole — reading text

measures to prevent expansion- contraction damage. b. If more than one pour is necessary, terminate each pour in a vertical plane and install 3/4-inch reinforcing rod dowels extending 18 inches into concrete on both sides of joint near corners of envelope. Pouring Concrete: Spade concrete carefully during pours to prevent voids under and between conduits and at exterior surface of envelope. Do not allow a heavy mass of concrete to fall directly onto ducts. Use a plank to direct concrete down sides of bank assembly to trench bottom. Allow concrete to flow to center of bank and rise up in middle, uniformly filling all open spaces. Do not use power- driven agitating equipment unless specifically designed for duct-bank application. Reinforcement: Reinforce concrete-encased duct banks where they cross disturbed earth and where indicated. Arrange reinforcing rods and ties without forming conductive or magnetic loops around ducts or duct groups. Forms: Use walls of trench to form side walls of duct bank where soil is self- supporting and concrete envelope can be poured without soil inclusions; otherwise, use forms. Minimum Space between Ducts: 3 inches between ducts and exterior envelope wall, 2 inches between ducts for like services, and 4 inches between power and signal ducts. Depth: Install top of duct bank at least 24 inches below finished grade in areas not subject to deliberate traffic, and at least 30 inches below finished grade in deliberate traffic paths for vehicles, unless otherwise indicated. Stub-Ups: Use manufactured duct elbows for stub-ups at poles and equipment and at building entrances through the floor, unless otherwise indicated. Extend concrete encasement throughout the length of the elbow. UNDERGROUND DUCTS DATE: 9/16/2013 OKALOOSA COUNTY WATER AND SEWER 16135 - 18 SECTION 16135 Russell Stephenson - Electrical Manhole Rehabilitation UNDERGROUND DUCTS 10. Stub-Ups: Use manufactured rigid steel conduit elbows for stub-ups at poles and equipment and at building entrances through the floor. a. Couple steel conduits to ducts with adapters designed for this purpose, and encase coupling with 3 inches of concrete. b. Stub-Ups to Equipment: For equipment mounted on outdoor concrete bases, extend steel conduit horizontally a minimum of 60 inches from edge of base. Install insulated grounding bushings on terminations at equipment. Warning Tape: Bury warning tape approximately 12 inches above all concrete- encased ducts and duct banks. Align tape parallel to and within 3 inches of the centerline of duct bank. Provide an additional warning tape for each 12-inch increment of duct-bank width over a nominal 18 inches. Space additional tapes 12 inches apart, horizontally. K. Direct-Buried Duct Banks: Support ducts on duct separators coordinated with duct size, duct spacing, and outdoor temperature. Space separators close enough to prevent sagging and deforming of ducts, with not less than 4 spacers per 20 feet of duct. Secure separators to earth and to ducts to prevent displacement during backfill and yet permit linear duct movement due to expansion and contraction as temperature changes. Stagger spacers approximately 6 inches between tiers. Excavate trench bottom to provide firm and uniform support for duct bank. Prepare trench bottoms as specified in Division 2 Section "Earthwork" for pipes less than 6 inches in nominal diameter. After installing first tier of ducts, backfill and compact. Start at tie-in point and work toward end of duct run, leaving ducts at end of run free to move with expansion and contraction as temperature changes during this process. Repeat procedure after placing each tier. After placing last tier, hand-place backfill to 4 inches over ducts and hand tamp. Firmly tamp backfill around ducts to provide maximum supporting strength. Use hand tamper only. After placing controlled backfill over final tier, make final duct connections at end of run and complete backfilling with normal compaction as specified in Division2 Section "Earthwork." Delete subparagraph below if dimensioned duct sections are shown on Drawings. Install ducts with a minimum of 3 inches between ducts for like services and 6 inches between power and signal ducts. UNDERGROUND DUCTS DATE: 9/16/2013 OKALOOSA COUNTY WATER AND SEWER 16135 - 19 SECTION 16135 Russell Stephenson - Electrical Manhole Rehabilitation UNDERGROUND DUCTS 7. Requirements in first subparagraph below exceed NFPA 70. Retain for conservative design. 8. Depth: Install top of duct bank at least 36 inches below finished grade, unless otherwise indicated. 9. Set elevation of bottom of duct bank below the frost line. 10. Direct-buried, PVC duct elbows in first subparagraph below are particularly vulnerable to damage by pulling lines when cable pulling tensions are high. Rigid steel conduit elbows are sometimes specified for these stub-ups to prevent such damage. However, concrete encasement of PVC duct elbows, together with reduced pulling tensions, is also used in these situations. Pulling tensions can be reduced by making duct runs from the closest manhole or handhole as short as possible and arranging duct banks so stub-up elbows have the longest possible radius. 5-inch (125-mm) duct elbows are available in standard radii of 24, 36, 48, and 60 inches (300, 900, 1200, and 1500 mm) and greater. Coordinate with Drawings and see Editing Instruction No. 3 in the Evaluations. 11. Retain one of first two subparagraphs and associated subparagraphs below to specify type of stub-ups for direct-buried ducts in Project. © 12. Install manufactured duct elbows for stub-ups at poles and equipment and at building entrances through the floor, unless otherwise indicated. Encase elbows for stub-up ducts throughout the length of the elbow. 13. Install manufactured rigid steel conduit elbows for stub-ups at poles and equipment and at building entrances through the floor. a. Couple steel conduits to ducts with adapters designed for this purpose, and encase coupling with 3 inches of concrete. b. For equipment mounted on outdoor concrete bases, extend steel conduit horizontally a minimum of 60 inches from edge of equipment pad or foundation. Install insulated grounding bushings on terminations at equipment. 14. Warning Planks: Bury warning planks approximately 12 inches above direct- buried ducts and duct banks, placing them 24 inches o.c. Align planks along the width and along the centerline of duct bank. Provide an additional plank for each 12-inch increment of duct-bank width over a nominal 18 inches. Space additional planks 12 inches apart, horizontally. @ UNDERGROUND DUCTS DATE: 9/16/2013 OKALOOSA COUNTY WATER AND SEWER 16135 - 20 SECTION 16135 Russell Stephenson - Electrical Manhole Rehabilitation UNDERGROUND DUCTS 3.5 INSTALLATION OF CONCRETE MANHOLES, HANDHOLES, AND BOXES A. _ Cast-in-Place Manhole Installation: 1. Finish interior surfaces with a smooth-troweled finish. 2. | Windows for Future Duct Connections: Form and pour concrete knockout panels 1-1/2 to 2 inches thick, arranged as indicated. Cast-in-place concrete, formwork, and reinforcement are specified in Division 3 Section "Cast-in-Place Concrete." Go B. Precast Concrete Handhole and Manhole Installation: 1. Comply with ASTM C 891, unless otherwise indicated. 2. Install units level and plumb and with orientation and depth coordinated with connecting ducts to minimize bends and deflections required for proper entrances. Unless otherwise indicated, support units on a level bed of crushed stone or gravel, graded from |-inch sieve to No. 4 sieve and compacted to same density as adjacent undisturbed earth. vs) C. Elevations: 1. Manhole Roof: Install with rooftop at least 15 inches below finished grade. 2 Manhole Frame: In paved areas and trafficways, set frames flush with finished grade. Set other manhole frames 1 inch above finished grade. 3. Install handholes with bottom below the frost line. 4. Handhole Covers: In paved areas and trafficways, set surface flush with finished grade. Set covers of other handholes 1 inch above finished grade. 5. Where indicated, cast handhole cover frame integrally with handhole structure. D. Drainage: Install drains in bottom of manholes where indicated. Coordinate with drainage provisions indicated. E. Manhole Access: Circular opening in manhole roof; sized to match cover size. 1. | Manholes with Fixed Ladders: Offset access opening from manhole centerlines to align with ladder. 2. — Install chimney, constructed of precast concrete collars and rings to support frame and cover and to connect cover with manhole roof opening. Provide moisture- tight masonry joints and waterproof grouting for cast-iron frame to chimney. UNDERGROUND DUCTS DATE: 9/16/2013 @ OKALOOSA COUNTY WATER AND SEWER 16135 - 21 SECTION 16135 Russell Stephenson - Electrical Manhole Rehabilitation UNDERGROUND DUCTS 3.6 Waterproofing: Apply waterproofing to exterior surfaces of manholes and handholes after concrete has cured at least three days. After ducts have been connected and grouted, and before backfilling, waterproof joints and connections and touch up abrasions and scars. Waterproof exterior of manhole chimneys after mortar has cured at least three days. Dampproofing: Apply dampproofing to exterior surfaces of manholes and handholes after concrete has cured at least three days. Dampproofing materials and installation are specified in Division 7 Section "Bituminous Dampproofing." After ducts have been connected and grouted, and before backfilling, dampproof joints and connections and touch up abrasions and scars. Dampproof exterior of manhole chimneys after mortar has cured at least three days. Coordinate paragraph below with Drawings. Delete second option if nonmetallic cable racks are specified. Hardware: Install removable hardware, including pulling eyes, cable stanchions, and cable arms, and insulators, as required for installation and support of cables and conductors and as indicated. Fixed Manhole Ladders: Arrange to provide for safe entry with maximum clearance from cables and other items in manholes. Field-Installed Bolting Anchors in Manholes and Concrete Handholes: Do not drill deeper than 3-7/8 inches for manholes and 2 inches for handholes, for anchor bolts installed in the field. Use a minimum of two anchors for each cable stanchion. Warning Sign: Install "Confined Space Hazard" warning sign on the inside surface of each manhole cover. INSTALLATION OF HANDHOLES AND BOXES OTHER THAN PRECAST CONCRETE Install handholes and boxes level and plumb and with orientation and depth coordinated with connecting ducts to minimize bends and deflections required for proper entrances. Use box extension if required to match depths of ducts, and seal joint between box and extension as recommended by the manufacturer. Unless otherwise indicated, support units on a level bed of crushed stone or gravel, graded from 1/2-inch sieve to No. 4 sieve and compacted to same density as adjacent undisturbed earth. UNDERGROUND DUCTS DATE: 9/16/2013 OKALOOSA COUNTY WATER AND SEWER 16135 - 22 SECTION 16135 Russell Stephenson - Electrical Manhole Rehabilitation UNDERGROUND DUCTS C. Elevation: In paved areas and traffic ways, set so cover surface will be flush with finished grade. Set covers of other handholes | inch above finished grade. D. Install handholes and boxes with bottom below the frost line. E. Install removable hardware, including pulling eyes, cable stanchions, cable arms, and insulators, as required for installation and support of cables and conductors and as indicated. Select arm lengths to be long enough to provide spare space for future cables, but short enough to preserve adequate working clearances in the enclosure. F. Field-cut openings for ducts and conduits according to enclosure manufacturer's written instructions. Cut wall of enclosure with a tool designed for material to be cut. Size holes for