UNDERGROUND DUCT BANK

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Nov 25, 2013 (3 years and 9 months ago)

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University of Manitoba



UN
DERGROUND DUCT BANK

Section 16127







Req. #

Page
1




Date revised December 18
, 2012



1.1

RELATED WORK


.1

Excavation and Backfilling


Section 02200

.2

Concrete Form Work



Section 03100

.3

Basic Electrical Materials

and Methods




Section 16050

.4

Conduit





Section 16111


1.2

SUBMITTALS



.1

Submit shop drawings in accordance with Sec
tion 16050 for precast manholes.


2.1

CONDUIT


.1

Rigid galvanized steel, rigid PVC duct, encased in reinforced concrete envelope, size and type
as indicated.


2.2

FITTINGS



.1

Rigid PVC opaque solvent welded
-
type watertight couplings, bell end fittings,
plugs, caps,
adaptors as required to make complete installation.

.2

Expansion joints as required.

.3

Rigid steel threaded couplings, bell end fittings, pre
-
manufactured bends, caps, etc. as
required.


2.3

PRECAST CONCRETE MANHOLES


.1

Precast concrete manh
oles or pullboxes as indicated.


2.4

MANHOLE FRAMES AND COVERS


.1

Cast iron manhole frames and covers as indicated.


2.5

GROUNDING



.1

Ground rods in Section 16451 for cable rack grounding as indicated.


2.6

CABLE RACKS



.1

Hot dipped galvanized cable
racks and supports as indicated.

.2

½" x 4" (13x100mm) preset inserts for rack mounting as indicated.


2.7

WIRE




.1

Wire in conduit to Section 16120.


2.8

CABLE PULLING EQUIPMENT




.1

3/4" (19mm) mule tape shall be pulled continuous throughout each duct

run with 10' (3m)
slack at each end.


3.1

INSTALLATION OF DUCT





.1

Install reinforced concrete encased underground duct banks and manholes.

.2

Build duct bank and manholes on undisturbed soil or on well compacted granular fill not less
than 6" (150m
m)
thick

compacted to 95% of maximum proctor dry density.

.3

Open trench completely along entire length before ducts are laid and ensure that no
obstructions will necessitate change in grade.

.4

Install ducts at elevations as indicated and with minimum slo
pe of 1 to 400.

.5

Install base spacers at maximum intervals of 5'(1.5m)
leveled

to grades indicated, from
bottom layer of ducts.

.6

Lay conduits with configuration and reinforcing as indicated with preformed, interlocking, rigid
plastic spacers to maintai
n spacing between ducts of not less than 3" (75mm) horizontally and
vertically. Stagger joints in adjacent layers at least 6"(150mm) and make joints watertight.
Encase duct bank with 3" (75mm) thick concrete cover.

.7

Make transitions, offsets and change
s in directions using 5° bend sections. Do not exceed a
total of 20° with duct offset.


University of Manitoba



UN
DERGROUND DUCT BANK

Section 16127







Req. #

Page
2




Date revised December 18
, 2012




.8

Use bell ends at duct terminations.

.9

Terminate duct runs with a duct couplings set flush with the end of the concrete envelope
when dead ending duct bank for futu
re extension.

.10

Cut, trim and taper ends of ducts in field to manufacturer’s recommendations.

.11

Allow concrete to attain 50% of its specified strength before backfilling.

.12

Use anchors, ties and trench jacks as required to secure ducts and prevent mo
ving during
pouring of concrete. Tie ducts to spacers with twine or other non
-
metallic material. Remove
weights or wood braces before concrete has set and fill voids.

.13

Install end caps on empty ducts to prevent entrance of foreign materials.

.14

Immed
iately after pouring of concrete, pull through each duct, a wooden madrel no less than
12" (300mm) long and of a diameter 1/4" (6mm) less than internal diameter of duct, followed
by a stiff bristle brush to remove sand, earth and other foreign matter. Avo
id distributing or
damaging ducts where concrete has not set completely. Pull stiff bristle brush through each
duct immediately before pulling in cables. Install pull cords in empty ducts.


3.2

MANHOLES



.1

Install precast manholes as indicated. Provi
de floor drain fittings in bottom of manhole. Co
-
ordinate the connection to the drainage system with Division 15.


3.3

INSPECTIONS



.1

Advise Consultant that he may review duct banks prior to pouring and be present during pour
of concrete and clean out.


3.4

AS
-
CONSTRUCTED DRAWINGS




.1

Include on As
-
constructed Drawings, exact dimensioned position and routing of all
underground duct banks, manholes, etc.


3.5

CO
-
ORDINATION


.1

Confirm the locations of all existing underground services, wiring, etc., prio
r to any trenching
or installation of new Pole Bases., etc. The Electrical Contractor shall employ a qualified firm
to survey and mark out all existing underground services which may be encountered
(Electrical, Telephone, Sewer, Gas, Water, etc.). Univers
ity Physical Plant underground
service map shall be consulted with Physical Plant staff to assist contractor prior to survey.
Upon completion of underground work, service map must be updated to reflect changes.