**Construction Specification 744---Corrugated Polyethylene Tubing**

**1. Scope**

The work consists of furnishing and installing tubing and the necessary
fittings and appurtenances as shown on the drawings and as outlined in
this specification.

**2. Material**

Corrugated polyethylene tubing and fittings shall conform to the
requirements of ASTM F 405, ASTM F 667, ASTM F 894, AASHTO M 252, or
AASHTO M 294 for the appropriate tubing sizes and fittings.

Fittings and joints shall conform to the requirements of the applicable
specification referenced in the ASTM or AASHTO specification for the
pipe and the requirements shown on the drawings.

When perforations are specified, the water inlet area shall be a minimum
of 1 square inch per lineal foot of tubing. The inlets either shall be
circular perforations or slots equally spaced along the length and
circumference of the tubing. Unless otherwise specified, circular
perforations shall not exceed 3/16 inch in diameter, and slot
perforations shall not be more that 1/8 inch wide.

Geotextile filter socks, when required, shall meet the material
requirements outlined in section 9 of this specification.

Granular bedding material, when specified, shall conform to the
requirements specified in section 9 of this specification.

The tubing shall be appropriately marked with ASTM or AASHTO
designation.

**3. Handling and storage**

Tubing shall be delivered to the job site and handled by means that
provide adequate support to the tubing and do not subject it to undue
stresses or damage. When handling and placing corrugated polyethylene
tubing, 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.

Tubing shall be stored on a relatively flat surface so that the full
length of the tube is evenly supported. Unless the tube 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**

Unless otherwise specified or approved by the engineer, excavation for
and subsequent installation of each tube line shall begin at the outlet
end and progress upgrade. The trench or excavation for the tubing shall
be constructed to the lines, depths, cross sections, and grade shown on
the drawings, specified in Section 9 of this specification, or as
approved by the engineer.

Trench shields, shoring and bracing, or other suitable methods necessary
to safeguard the contractor\'s employees and the works of improvement
and to prevent damage to the existing improvements shall be furnished,
placed, and subsequently removed by the contractor.

**5. Preparing the tubing bed and blinding the tubing**

When a granular filter or envelope is specified, the filter or envelope
material shall be placed in the bottom of the trench just before the
tubing is laid. The tubing shall then be laid and the filter and
envelope material placed to a depth over the top of the tubing of not
less than that shown on the drawings or as specified in section 9 of
this specification.

When a granular filter or envelope is not specified, the bottom of the
trench shall be shaped to form a semicircular or trapezoidal groove in
its center. This groove shall provide support for not less than a fourth
of the outside circumference of the tubing. After the tubing is placed
in the excavated groove, it shall be capped with friable material from
the sides of the trench. The friable material shall be placed around the
tubing, completely filling the trench to a depth of at least 3 inches
over the top of the tubing. For material to be suitable, it must not
contain hard clods, rocks, frozen soil, or fine material that will cause
a silting hazard to the drain. Tubing placed during any day shall be
blinded (place required soil material around and over pipe) and
temporarily capped before construction activities are completed for that
day.

**6. Placement and joint connections**

All tubing shall be installed to grade as shown on the drawings. After
the tubing is placed in the trench and blinded, allow sufficient time
for the tubing to adapt to the soil temperature before backfilling.

Maximum allowable stretch of the tubing is 5 percent. Special
precautions must be implemented on hot, bright days to ensure that the
stretch limit is not exceeded and excessive deflection does not occur as
a result of installation procedures, including backfill operations.

Unless otherwise specified in section 9 of this specification or shown
on the drawings, connections are made with manufactured junctions
comparable in strength with the specified tubing. All split fittings
shall be securely fastened with nylon cord or plastic zip ties before
any backfill is placed. All buried ends shall be supplied with end caps
unless otherwise approved by the engineer.

**7. Backfilling**

Unless otherwise specified in section 9 of this specification, the
backfilling of the trench shall be as shown on the drawings and
completed as rapidly as is consistent with the soil conditions.
Automatic backfilling machines may be used only when approved by the
engineer. Backfill shall extend above the ground surface and be well
rounded and centered over the trench.

**8. Measurement and payment**

***Method 1---***For items of work for which specific unit prices are
established in the contract, the quantity of each kind and size of
tubing is determined to the nearest foot of length measured along the
centerline of the installed tubing. Payment for each kind and size of
tubing is made at the contract unit price for that kind and size of
tubing. Such payment constitutes full compensation for all labor,
equipment, tools, and all other items necessary and incidental to
furnishing, transporting, and installing the tubing, including
excavation, shoring, geotextile or granular filter (when specified),
backfill and all fittings, appurtenances, and other items required to
complete the work. Payment for appurtenances listed separately in the
bid schedule is made at the contract unit price(s) for the size and type
of appurtenance listed.

***Method 2---***For items of work for which specific unit prices are
established in the contract, the quantity of each kind, size, and class
of tubing is determined to the nearest foot by measurement of the laid
length along the crown centerline of the tubing. Payment for each kind,
size, and class of tubing is made at the contract unit price for the
kind, size, and class. Such payment constitutes full compensation for
furnishing, transporting, and installing the tubing, including shoring,
all fittings, thrust blocks, appurtenances, and other items necessary
and incidental to the completion of the work. Payment for appurtenances
listed separately in the bid schedule are made at the contract prices
for those items.

Compensation for any item of work described in the contract, but not
listed in the bid schedule, is included in the payment for the item of
work to which it is made subsidiary. Such items and the items to which
they are made subsidiary are identified in section 9 of this
specification.

**9. Items of work and construction details**

[Bid Item 15, Corrugated Polyethylene Tubing, 18 in. dia.]{.underline}

(1) This item shall consist of furnishing and installing the 18-inch
    diameter smooth-lined corrugated tubing as shown on the drawings.

(2) Tubing shall conform to the requirements of AASHTO Specification M
    294.

(3) Joints shall be rubber gasketed.

(4) Backfill methods shall be as shown on the drawings.

(5) Measurement and payment will be by Method 1.