### **ITEM D-705 PIPE UNDERDRAINS FOR AIRPORTS**

DESCRIPTION

**705-1.1**  This item shall consist of the construction of pipe drains
in accordance with these specifications and in reasonably close
conformity with the lines and grades shown on the plans.

MATERIALS

**705-2.1 GENERAL.**  Materials shall meet the requirements shown on the
plans and specified below.

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> **The Engineer should indicate the required class, schedule, SDR,
> gage, and/or strength of pipe desired.**

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**705-2.2 PIPE.** The pipe shall be of the type called for on the plans
or in the proposal and shall be in accordance with the following
appropriate requirements.

> Perforated Concrete Pipe ASTM C 444
>
> Porous Concrete Pipe ASTM C 654
>
> Polymer Precoated Perforated Corrugated Steel Pipe ASTM A 762
>
> Perforated Corrugated Aluminum Alloy Pipe AASHTO M 196
>
> Smooth‑Wall Perforated PVC Pipe ASTM F 758
>
> Poly (Vinyl Chloride) Ribbed Drain Pipe & Fittings
>
> Based on Controlled Inside Diameter ASTM F 794
>
> Poly (Vinyl Chloride)(PVC) Corrugated Sewer
>
> Pipe With a Smooth Interior and Fittings ASTM F 949
>
> Perforated Corrugated Steel Pipe ASTM A 760
>
> Bituminous‑Coated Perforated Corrugated AASHTO M 196
>
> Aluminum Alloy Pipe and M 190
>
> Corrugated Polyethylene Drainage Tubing (all types) AASHTO M 252
>
> Corrugated Polyethylene Pipe, 300 to 1200 mm Diameter (all types)
> AASHTO M 294M
>
> Poly (Vinyl Chloride) (PVC) Profile Wall Drain Pipe and AASHTO M 304
>
> Fittings Based on Controlled Inside Diameter

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> **The Engineer shall select the pipe used for the project and may
> delete inappropriate requirements from paragraph 705-2.2 and from the
> list of material requirements.**

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**705-2.3 JOINT MORTAR.**  Pipe joint mortar shall consist of one part
portland cement and two parts sand.  The portland cement shall conform
to the requirements of ASTM C 150, Type I.  The sand shall conform to
the requirements of ASTM C 144.

**705-2.4 ELASTOMERIC SEALS.**  Elastomeric seals shall conform to the
requirements of ASTM F 477.

**705-2.5 POROUS BACKFILL.**  Porous backfill shall be free of clay,
humus, or other objectionable matter, and shall conform to the gradation
in Table 1 when tested in accordance with ASTM C 136.

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  **TABLE 1. GRADATION                            
  OF POROUS BACKFILL**                            

  Sieve Designation      Percentage by Weight     
  (square openings)      Passing Sieves           

                         Porous Material No. 1    Porous Material No. 2

  1‑1/2 inch (38 mm)                              100

  1 inch (25 mm)                                  90 - 100

  3/8 inch (9.5 mm)      100                      25 - 60

  No. 4 (4.75 mm)        95 -- 100                5 - 40

  No. 8 (2.36 mm)                                 0 - 20

  No. 16 (1.18 mm)       45 -- 80                 

  No. 50 (0.30 mm)       10 -- 30                 

  No. 100 (0.15 mm)      0 -- 10                  
  ---------------------- ------------------------ -----------------------

When two courses of porous backfill are specified in the plans, the
finer of the materials shall conform to particle size tabulated herein
for porous material No. 1.  The coarser granular material shall meet the
gradation given in the tabulation for porous material No. 2.

**705-2.6. GRANULAR MATERIAL.** Granular material used for backfilling
shall conform to the requirements of ASTM D 2321 for Class IA, IB, or II
materials, or shall meet the requirements of AASHTO Standard
Specification for Highway Bridges Section 30.

**705-2.7. FILTER FABRIC.** The filter fabric shall conform to the
requirements of AASHTO M 288-99, Class 2.

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  **TABLE 2**                                                      

  **Fabric                                     **Test Method**     **Test
  Property**                                                       Requirement**

  **Grab Tensile                               **ASTM D 4632**     **125 min**
  Strength, lbs**                                                  

  **Grab Tensile                               **ASTM D 4632**     **50 min**
  Elongation %**                                                   

  **Burst                                      **ASTM D 3785**     **125 min**
  Strength, psi**                                                  

  **Trapezoid Tear                             **ASTM D 4533**     **55 min**
  Strength, lbs**                                                  

  **Puncture                                   **ASTM D 4833**     **40 min**
  Strength, lbs**                                                  

  **Abrasion,                                  **ASTM D 4886**     **15 max loss**
  lbs**                                                            

  **Equivalent                                 **ASTM D 4751**     **70-100**
  Opening Size**                                                   

  **Permittivity                               **ASTM D 4491**     **0.80**
  sec^-1^**                                                        

  **Accelerated                                **ASTM D 4355**     **70**
  Weathering**                                                     

                   **(UV Stability)**          **\*(500 hrs        
                                               exposure)**         

                   **(Strength Retained - %)**                     
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> **The Engineer shall specify Class 2 unless sufficient survivability
> information is available for a reduction in minimum property
> requirements. Permittivity and Apparent Opening Size requirements
> shall be based on knowledge of in situ soil.**

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**705-2.8. CONTROLLED LOW STRENGTH MATERIAL (CLSM).** Controlled low
strength material shall conform to the requirements of Item P-153. When
CLSM is used all joints shall have elastomeric seals.

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> **Specification Item P-153 Controlled Low Strength Material
> (CLSM)contains guidance for use of CLSM. The locations where CLSM is
> permitted shall be shown on the plans.**

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CONSTRUCTION METHODS

**705-3.1 EQUIPMENT.** All equipment necessary and required for the
proper construction of pipe underdrains shall be on the project, in
first-class working condition, and approved by the Engineer before
construction is permitted to start.

**705-3.2 EXCAVATION.** The width of the pipe trench shall be sufficient
to permit satisfactory jointing of the pipe and thorough tamping of the
bedding material under and around the pipe, but shall not be less than
the external diameter of the pipe plus 6 inches (150 mm) on each side.
The trench walls shall be approximately vertical.

Where rock, hardpan, or other unyielding material is encountered, it
shall be removed below the foundation grade for a depth of at least 4
inches (100 mm). The excavation below grade shall be backfilled with
selected fine compressible material, such as silty clay or loam, and
lightly compacted in layers not over 6 inches (150 mm) in uncompacted
depth to form a uniform but yielding foundation.

Where a firm foundation is not encountered at the grade established, due
to soft, spongy, or other unstable soil, the unstable soil shall be
removed and replaced with approved granular material for the full trench
width. The Engineer shall determined the depth of removal necessary. The
granular material shall be compacted to provide adequate support for the
pipe.

Excavated material not required or acceptable for backfill shall be
disposed of by the Contractor as directed by the Engineer. The
excavation shall not be carried below the required depth; when this is
done, the trench shall be backfilled at the Contractor\'s expense with
material approved by the Engineer and compacted to the density of the
surrounding earth material.

The bed for the pipe shall be so shaped that at least the lower quarter
of the pipe shall be in continuous contact with the bottom of the
trench. Spaces for the pipe bell shall be excavated accurately to size
to clear the bell so that the barrel supports the entire weight of the
pipe.

The Contractor shall do such trench bracing, sheathing, or shoring
necessary to perform and protect the excavation as required for safety
and conformance to governing laws. Unless otherwise provided, the
bracing, sheathing, or shoring shall be removed by the Contractor after
the completion of the backfill to at least 12 inches (300 mm) over the
top of the pipe. The sheathing or shoring shall be pulled as the
granular backfill is placed and compacted to avoid any unfilled spaces
between the trench wall and the backfill material. The cost of bracing,
sheathing, or shoring, and the removal of same, shall be included in the
unit price bid per foot (meter) for the pipe.

**705-3.3 LAYING AND INSTALLING PIPE.**

**a. Concrete Pipe.** The laying of the pipe in the finished trench
shall be started at the lowest point and laid upgrade. When bell and
spigot pipe is used, the bells shall be laid upgrade. If tongue and
groove pipe is used, the groove end shall be laid upgrade. Holes in
perforated pipe shall be placed down, unless otherwise shown on the
plans. The pipe shall be firmly and accurately set to line and grade so
that the invert will be smooth and uniform. Pipe shall not be laid on
frozen ground.

Pipe which is not true in alignment, or which shows any settlement after
laying, shall be taken up and relaid without extra compensation.

**b. Metal Pipe.** The metal pipe shall be laid with the separate
sections joined firmly together with bands, with outside laps of
circumferential joints pointing upgrade, and with longitudinal laps on
the sides. Any metal in the pipe or bands that is not protected
thoroughly by galvanizing shall be coated with a suitable asphaltum
paint.

During installation, the asphalt-protected pipe shall be handled without
damaging the asphalt coating. Any breaks in the bitumen or treatment of
the pipe shall be refilled with the type and kind of bitumen used in
coating the pipe originally.

**c. PVC or Polyethylene Pipe.**  PVC or polyethylene pipe shall be
installed in accordance with the requirements of ASTM D 2321 or AASHTO
Standard Specification for Highway Bridges Section 30. Perforations
shall meet the requirements of AASHTO M 252 or M 294 Class 2, unless
otherwise indicated on the plans. The pipe shall be laid accurately to
line and grade.

**d. All Types of Pipe.**  The upgrade end of pipelines, not terminating
in a structure, shall be plugged or capped as approved by the Engineer.

Unless otherwise shown on the plans, a 4‑inch (100 mm) bed of granular
backfill material shall be spread in the bottom of the trench throughout
the entire length under all perforated pipe underdrains.

Pipe outlets for the underdrains shall be constructed when required or
shown on the plans.  The pipe shall be laid with tight‑fitting joints. 
Porous backfill is not required around or over pipe outlets for
underdrains.  All connections to other drainage pipes or structures
shall be made as required and in a satisfactory manner.  If connections
are not made to other pipes or structures, the outlets shall be
protected and constructed as shown on the plans.

**e. Filter Fabric.** The filter fabric shall be installed in accordance
with the manufacturer\'s recommendations, or in accordance with AASHTO M
288-99 APPENDIX, unless otherwise shown on the plans.

**705-3.4 MORTAR.**  The mortar shall be of the desired consistency for
caulking and filling the joints of the pipe and for making connections
to other pipes or to structures.  Mortar that is not used within 45
minutes after water has been added shall be discarded.  Retempering of
mortar shall not be permitted.

**705-3.5 JOINTS IN CONCRETE PIPE.**  When open or partly open joints
are required or specified, they shall be constructed as indicated on the
plans.  The pipe shall be laid with the ends fitted together as
designed.  If bell and spigot pipe is used, mortar shall be placed along
the inside bottom quarter of the bell to center the following section of
pipe.

The open or partly open joints shall be surrounded with granular
material meeting requirements of porous backfill No. 2 or as indicated
on the plans.  This backfill shall be placed so its thickness will be
not less than 3 inches (75 mm) nor more than 6 inches (150 mm), unless
otherwise shown on the plans.

When the original material excavated from the trench is impervious,
commercial concrete sand or granular material meeting requirements of
porous backfill No. 1 shall surround porous backfill No. 2, as shown on
the plans or as directed by the Engineer.

When the original material excavated from the trench is pervious and
suitable, it may be used as backfill in lieu of porous backfill No. 1,
when indicated on the plans or as directed by the Engineer.

**705-3.6 BACKFILLING.**

**a. Earth.**  All trenches and excavations shall be backfilled within a
reasonable time after the pipes are installed, unless other protection
of the pipe is directed.  The backfill material shall be selected
material from excavation or borrow; material which is placed within a
nominal pipe diameter distance at the sides of the pipe and 1 foot (30
cm) over the top shall be material that can be readily compacted.  It
shall not contain stones retained on a 3‑inch (75 mm) sieve, frozen
lumps, chunks of highly plastic clay, or any other material that is
objectionable to the Engineer.  The material shall be moistened or
dried, if necessary to be compacted by the method in use.  Backfill
material shall be approved by the Engineer.  Special care shall be taken
in placing the backfill.  Great care shall be used to obtain thorough
compaction under the haunches and along the sides to the top of the
pipe.

The backfill shall be placed in loose layers not exceeding 6 inches (150
mm) in depth under and around the pipe, and not exceeding 8 inches (200
mm) over the pipe.  Successive layers shall be added and thoroughly
compacted by hand and pneumatic tampers, approved by the Engineer, until
the trench is completely filled and brought to the proper elevation. 
Backfilling shall be done in a manner to avoid injurious top or side
pressures on the pipe.

In embankments and for other areas outside of pavements, the backfill
shall be compacted to the density required for embankments in unpaved
areas under Item P‑152.  Under paved areas, the subgrade and any
backfill shall be compacted to the density required for embankments for
paved areas under Item P‑152.

**b. Granular Material.**  When granular backfill is required, its
placement in the trench and about the pipe shall be as shown on the
plans.  Special care shall be taken in placing the backfill.  The
granular backfill shall not contain a damaging amount of foreign matter,
nor shall earth from the sides of the trench or from the windrow be
allowed to filter into the backfill.  When required by the Engineer, a
template shall be used to properly place and keep separate the two sizes
of backfill.  The backfill shall be placed in loose layers not exceeding
6 inches (150 mm) in depth and compacted by hand and pneumatic tampers
to the requirements as given for earth backfill.  Backfilling shall be
done in a manner to avoid injurious top or side pressure on the pipe. 
The granular backfill shall be made to the elevation of the trench, as
shown on the plans.

When perforated pipe is specified, granular backfill material shall be
placed along the full length of the pipe.  The position of the granular
material shall be as shown on the plans.  If the original material
excavated from the trench is pervious and suitable, it shall be used in
lieu of porous backfill No. 1.

When porous backfill is to be placed in paved or adjacent areas prior to
the completion of grading or subgrade operations, the backfill material
shall be placed immediately after laying the pipe.  The depth of this
granular backfill shall be not less than 12 inches (300 mm), measured
from the top of the underdrain.  During subsequent construction
operations, this minimum backfill of 12 inches (300 mm) of depth shall
not be disturbed until such time as the underdrains are to be
completed.  When the underdrains are to be completed, the unsuitable
material shall be removed until the porous backfill is exposed.  That
part of the porous backfill that contains objectionable material shall
be removed and replaced with suitable material.  The cost of removing
and replacing any such unsuitable material shall be borne by the
Contractor.

Whenever a granular subbase blanket course is to be used under pavements
which extends several feet beyond the edge of paving to the outside edge
of the underdrain trench, the granular backfill material over the
underdrains shall be placed in the trench up to an elevation of 2 inches
(50 mm) above the bottom surface of the granular subbase blanket
course.  Immediately prior to the placing of the granular subbase
blanket course, the Contractor shall blade this excess trench backfill
from the top of the trench onto the adjacent subgrade where it can be
incorporated into the granular subbase blanket course.  Any unsuitable
material that remains over the underdrain trench shall be removed and
replaced.  The subbase material shall be placed to provide clean contact
between the subbase material and the underdrain granular backfill
material for the full width of the underdrain trench.

**c**. **Controlled Low Strength Material (CLSM).** Controlled low
strength material shall conform to the requirements of Item P-153.

**d. Deflection Testing.** The Engineer may at any time, not
withstanding previous material acceptance, reject or require
re-installation of pipe that exceeds 5 percent deflection when measured
in accordance with ASTM D 2321, including Appendices.

**705-3.7 CONNECTIONS.**  When the plans call for connections to
existing or proposed pipe or structures, these connections shall be
watertight and made so that a smooth uniform flow line will be obtained
throughout the drainage system.

**705-3.8 CLEANING AND RESTORATION OF SITE.**  After the backfill is
completed, the Contractor shall dispose of all surplus material, dirt,
and rubbish from the site.  Surplus dirt may be deposited in
embankments, shoulders, or as ordered by the Engineer.  Except for paved
areas of the airport, the Contractor shall restore all disturbed areas
to their original condition.

METHOD OF MEASUREMENT

**705-4.1**  The length of pipe to be paid for shall be the number of
linear feet (meters) of pipe underdrains in place, completed, and
approved; measured along the centerline of the pipe from end or inside
face of structure to the end or inside face of structure, whichever is
applicable.  The several classes, types, and sizes shall be measured
separately.  All fittings shall be included in the footage as typical
pipe sections in the pipeline being measured.

**705-4.2**  The quantity of porous backfill to be paid for shall be the
number of cubic yards (cubic meters) of porous backfill No. 1 and No. 2,
complete in place and accepted, and shall be determined from the
dimensions given on the plans by typical trench sections indicating the
placement of porous backfill or dimensions ordered by the Engineer.

**705-4.3**  The quantity of filter fabric to be paid for shall be the
number of square yards (square meters) of filter fabric in place,
completed, and approved; and shall be determined from the dimensions
given on the plans by typical trench sections indicating the placement
of filter fabric or dimensions ordered by the Engineer.

BASIS OF PAYMENT

**705-5.1**  Payment will be made at the contract unit price per linear
foot (meter) for pipe underdrains of the type, class, and size
designated; at the contract unit price **\[per cubic yard (cubic
meter)\]\[per ton (metric ton)\]** for porous backfill No.1; the
contract unit price **\[per cubic yard (cubic meter)\]\[per ton (metric
ton)\]** for porous backfill No. 2, and at the contract unit price per
square yard (square meter) for filter fabric. **\[per linear foot
(meter) COMPLETE (including porous backfill and filter fabric.\]** These
prices shall be full compensation for furnishing all materials and for
all preparation, excavation, and installation of these materials, and
for all labor, equipment, tools, and incidentals necessary to complete
the item.

Payment will be made under:

Item D‑705‑5.1 **\[   \]** inch pipe (mm pipe) **\[   \]** per linear
foot (meter)

Item D‑705‑5.2 Porous Backfill No. 1---**\[per cubic yard (cubic
meter)\]\[per ton (metric ton)\]**

Item D‑705‑5.3 Porous Backfill No. 2---**\[per cubic yard (cubic
meter)\]\[per ton (metric ton)\]**

Item D‑705‑5.4 Filter Fabric---per square yard (square meter)

**\[Item D‑705‑5.5 \[   \] inch pipe (mm pipe) \[   \] per linear foot
(meter) COMPLETE (including porous backfill and filter fabric\]**

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> **The Engineer shall specify the size and type of pipe, filter fabric,
> and backfill material for each pipe size and type specified in the
> plans.**

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MATERIAL REQUIREMENTS

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      ASTM A 760       Corrugated Steel Pipe, Metallic‑Coated for Sewers
                       and Drains

                       

      ASTM A 762       Corrugated Steel Pipe, Polymer Precoated for
                       Sewers and Drains

                       

      ASTM C 136       Sieve Analysis of Fine and Coarse Aggregates

                       

      ASTM C 144       Aggregate for Masonry Mortar

                       

      ASTM C 150       Portland Cement

                       

      ASTM C 444       Perforated Concrete Pipe

                       

      ASTM C 654       Porous Concrete Pipe

                       

      ASTM D 2321      Underground Installation of Thermoplastic Pipe for
                       Sewers and Other Gravity-Flow Applications

                       

      ASTM D 3034      Type PSM Poly(Vinyl Chloride) (PVC) Sewer Pipe and
                       Fittings

                       

      ASTM F 477       Elastomeric Seals (Gaskets) for Joining Plastic
                       Pipe

                       

      ASTM F 758       Smooth‑Wall Poly(Vinyl Chloride) (PVC) Plastic
                       Underdrain Systems for Highway, Airport, and
                       Similar Drainage

                       

      ASTM F 794       Poly (Vinyl Chloride) Ribbed Drain Pipe & Fittings
                       Based on Controlled Inside Diameter

                       

      ASTM F 949       Poly (Vinyl Chloride)(PVC) Corrugated Sewer Pipe
                       with a Smooth Interior and Fittings

                       

      AASHTO M 190     Bituminous Coated Corrugated Metal Culvert Pipe
                       and Pipe Arches

                       

      AASHTO M 196     Corrugated Aluminum Alloy Culverts and Underdrains

                       

      AASHTO M 252     Corrugated Polyethylene Drainage Tubing

                       

      AASHTO M 288-99  Geotextile Specification for Highway Applications

                       

      AASHTO M 294M    Corrugated Polyethylene Pipe, 300 to 1200 mm
                       Diameter

                       

      AASHTO M 304     Poly (Vinyl Chloride) (PVC) Profile Wall Drain
                       Pipe and Fittings Based on Controlled Inside
                       Diameter

                       

      AASHTO           Standard Specifications for Highway Bridges
  --- ---------------- --------------------------------------------------

**END OF ITEM D-705**

**Intentionally Left Blank**

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