**Minnesota Construction Specification 45---Plastic Pipe**

**1. Scope**

The work consists of furnishing and installing plastic pipe (except
corrugated polyethylene tubing) and the necessary fittings and
appurtenances as shown on the drawings or as specified herein.

**2. Material**

Pipe, fittings, and gaskets shall conform to the requirements of
Material Specification 547, Plastic Pipe, and as specified in section 12
of this specification or as shown on the drawings.

Unless otherwise specified, concrete shall conform to the requirements
of MN Construction Specification MN32, Structure Concrete, and section 8
of this specification. Unless otherwise specified, earth backfill shall
conform to the requirements of MN Construction Specification MN23,
Earthfill. Unless otherwise specified, drainfill shall conform to the
requirements of Construction Specification MN24, Drainfill.

**3. Handling and storage**

Pipe shall be delivered to the job site and handled by means that
provide adequate support to the pipe and do not subject it to undue
stresses or damage. When handling and placing plastic pipe, care shall
be taken to prevent impact blows, abrasion damage, and gouging or
cutting (by metal edges and/or surface or rocks). The manufacturer\'s
special handling requirements shall be strictly observed. Special care
shall be taken to avoid impact when the pipe must be handled at a
temperature of 40 degrees Fahrenheit or less.

Pipe shall be stored on a relatively flat surface so that the barrels
are evenly supported. Unless the pipe is specifically manufactured to
withstand exposure to ultraviolet radiation, it shall be covered with an
opaque material when stored outdoors for 15 days or longer.

**4. Excavation**

Excavation shall be in accordance with MN Construction Specification
MN21, Excavation, and section 12 of this specification or as shown on
the drawings.

The pipe foundation shall be excavated a minimum of 4 inches lower than
the pipe grade shown on the drawings or staked in the field whenever
bedrock, boulders, cobbles, or other material that may cause pipe damage
is encountered at planned pipe grade.

**5. Laying the pipe**

Plastic pipe conduits complete with fittings and other related
appurtenances shall be installed to the lines and grades shown on the
drawings or specified in section 12 of this specification. The pipe
shall be installed such that no reversal of grade occurs between joints
unless otherwise shown on the drawings. The pipe shall not be dropped or
dumped on the bedding or into the pipe trench. The ground surface near
the pipe trench shall be free of loose rocks and stones greater than 1
inch in diameter. This ensures that rock will not be displaced and
impact the pipe.

Just before placement, each pipe section shall be inspected to ensure
that all foreign material is removed from inside the pipe. The pipe ends
and the couplings shall be free of foreign material when assembled. At
the completion of a work shift, all open ends of the pipeline shall be
temporarily closed off using a suitable cover or plug.

Care shall be taken to prevent distortion and damage during hot or cold
weather. During unusually hot weather (daytime high temperature of more
than 90° F), the pipe assembled in the trench shall be lightly
backfilled or shaded to keep it as near to ground temperature as
possible until final backfill is placed. Backfill operations should be
performed during daily construction periods when the ground temperature
and the temperature of the pipe do not vary more than 40 degrees
Fahrenheit.

Perforated pipe shall be installed with the perforations down and
oriented symmetrically about the vertical centerline. Perforations shall
be clear of any obstructions on the inside and outside of the pipe when
the pipe is approved by the engineer for backfill.

During installation, the pipe shall be firmly and uniformly bedded
throughout its entire length, to the depth and in the manner specified
in section 12 of this specification or as shown on the drawings. The
bell end shall be installed upstream. Bell-holes shall be placed in
bedding material under bells, couplings, and other fittings to assure
the pipe is uniformly supported throughout its entire length. Blocking
or mounding beneath the pipe to bring the pipe to final grade is not
permitted.

**6. Pipe embedment**

**Earth bedding---**The pipe shall be firmly and uniformly placed on
compacted earthfill bedding or an in-place earth material bedding of
ample bearing strength to support the pipe without noticeable
settlement. The earth material on which the pipe is placed shall be of
uniform density to prevent differential settlement.

Unless otherwise specified, a groove that closely conforms to the
outside surface of the pipe shall be formed in the bedding. The depth of
the groove shall be equal to or greater than 0.3 of the pipe diameter.

Earth bedding shall be compacted to a density not less than adjacent
undisturbed in-place earth material or be compacted earth backfill.
Earthfill material used for compacted earth bedding shall be free of
rocks or stones greater than 1 inch in diameter and earth clods greater
than 2 inches in diameter.

**Sand, gravel, or crushed rock bedding---**When sand, gravel, or
crushed rock bedding is specified, the pipe shall be firmly and
uniformly placed on the bedding material. Material for bedding shall not
exceed 1 inch in diameter. Unless otherwise specified in section 12 of
this specification or shown on the drawings, the coarse-grained bedding
material shall be carefully placed and compacted to a depth equal to or
greater than 0.3 of the diameter of the pipe above the bottom of the
pipe. The pipe shall be loaded sufficiently during backfilling and
compaction around the sides to prevent displacement of the pipe from its
final approved placement.

**Pipe encased in drainfill---**The pipe shall be firmly and uniformly
placed on bedding of specified drainfill. Drainfill shall be placed and
compacted as specified in section 12 of this specification or as shown
on the drawings to form a continuous uniform support around the entire
circumference of the pipe. The pipe shall be loaded sufficiently during
backfilling around the sides and during compaction to prevent
displacement of the pipe.

**7. Backfill**

**Initial backfill---**Unless otherwise specified, initial backfill to 6
inches above the top of the conduit is required. Earth haunching and
initial backfill material shall consist of soil material that is free of
rocks, stones, or hard clods more than 1 inch in diameter. Coarse
backfill material shall be the specified sand, gravel, crushed rock, or
drainfill material.

Initial backfill shall be placed in two stages. In the first stage
(haunching), backfill is placed to the pipe spring line (center of
pipe). In the second stage, it is placed to 6 inches above the top of
the pipe. The first stage material shall be worked carefully under the
haunches of the pipe to provide continuous support throughout the entire
pipe length. The pipe shall be loaded sufficiently during the compaction
of bedding under the haunches and around the sides of the pipe to
prevent displacement from its final approved placement. Within two feet
of the pipe, backfill shall be carefully placed and compacted by means
of hand tamping or manually directed power tampers or plate vibrators to
form a continuous uniform support around the pipe. The maximum thickness
of layers within 2 feet of the pipe shall be 4 inches before compaction
and at more than 2 feet, a maximum thickness before compaction shall be
6 inches. During compaction operations, care shall be taken to ensure
that the tamping or vibratory equipment does not come in contact with
the pipe and the pipe is not deformed or displaced.

When pressure testing is not specified, the pipe shall be covered with a
minimum of 6 inches of backfill material as soon as possible following
assembling of the pipe in the trench, but not later than within the same
day that placement has occurred. When pressure testing is specified,
sufficient backfill material shall be placed over the pipe to anchor the
conduit against movement during pressure testing activities.

**Final backfill---**Final backfill shall consist of placing the
remaining material required to complete the backfill from the top of the
initial backfill to the ground surface, including mounding at the top of
the trench. Final backfill material within 2 feet of the top of the pipe
shall be free of debris or rocks larger than 3 inches nominal diameter.
Coarse backfill material shall be the specified sand, gravel, crushed
rock, or drainfill. Final backfill shall be placed in approximately
uniform, compacted layers. Final backfill compaction requirements shall
be as specified in section 12 of this specification or as shown on the
drawings.

Vehicles or construction equipment shall not be allowed to cross the
pipe until the minimum earth cover and required density as specified in
section 12 of this specification has been obtained.

**8. Pipe encasement in concrete**

Concrete encasement shall be carefully placed to form a continuous
uniform support around the entire circumference of the pipe as specified
in section 12 of this specification or as shown on the drawings. Pipes
encased in concrete shall be securely anchored to prevent movement of
the pipe during concrete placement. A clear distance of 1.5 inches shall
be maintained between the pipe and the reinforcing steel.

The concrete for the encasement shall conform to the requirements of MN
Construction Specification MN32, Structure Concrete, unless otherwise
specified.

**9. Joints**

Unless otherwise specified in section 12 of this specification or shown
on the drawings, joints shall be either bell and spigot type with
elastomeric gaskets, coupling type, solvent cement bell and spigot, or
jointed by butt heat fusion. When a lubricant is required to facilitate
joint assembly, it shall be a type having no deleterious affect on the
gasket or pipe material.

Pipe joints shall be watertight at the pressures specified except where
unsealed joints are indicated.

Pipe shall be installed and joined in accordance with the
manufacturer\'s recommendations. Laying deflections and joint fitting or
stab depths shall be within the manufacturer\'s recommended tolerances.

When solvent cement joints are specified for PVC or ABS pipe and
fittings, they shall be made in accordance with the following ASTMs and
the related appendix of each ASTM: D 2855 for PVC pipe and fittings and
D 2235 for ABS pipe and fittings.

Flanged, banded, heat-fusion, or elastomeric-sealed mechanical joints
shall be used when joining polyethylene (PE) and high density
polyethylene (HDPE) pipe and fittings unless otherwise specified in
section 12 of this specification or as shown on the drawings.

Pipe ends shall be cut square and be deburred to provide a uniform,
smooth surface for the jointing process. Reference marks shall be placed
on the spigot ends to assist in determining when proper seating depth
has been achieved within the joint.

**10. Fittings**

Unless otherwise specified, steel fittings, valves, and bolted
connections shall be painted or coated as recommended by the
manufacturer.

Fittings for nonpressure pipe shall be of the same or similar material
as the pipe and shall provide the same durability, watertightness, and
strength as the pipe unless otherwise specified.

**11. Thrust blocks and anchors**

When specified, concrete thrust blocks and anchors shall be installed as
shown on the drawings or specified in section 12 of this specification.

The concrete for the thrust blocks and anchors shall conform to the
requirements of MN Construction Specification MN32, Structure Concrete,
unless otherwise specified in section 12 of this specification.

The thrust block cavity shall be hand dug into undisturbed soil or
previously placed compacted backfill. The cavity shall be formed with
soil or wood to hold the freshly placed concrete without displacement
until an initial set has occurred.

When excavation beyond the designated trench widths and depths as shown
on the drawings or specified in section 12 of this specification occurs
at locations where installation of concrete thrust blocks is required,
the contractor shall install an alternative thrust block provision. The
concrete thrust block shall have a thickness of one pipe diameter and a
contact face area that shall be formed against the pipe as shown on the
drawings or specified in section 12 of this specification. Backfill
shall be placed on all sides of the thrust block and to the sides of the
excavation. It shall be compacted as specified for initial backfill.

**12. Construction details**