610PIPE UNDERDRAIN AND PAVEMENT BASE DRAIN

610.1DESCRIPTION—This work is construction of pipe underdrains, of the type and size indicated, and

pavement base drains.

610.2MATERIAL—

1.a Type. Use the type indicated. If not indicated, use any one of the types listed below.

1.b Size. For circular pipe, unless otherwise indicated, use pipe with a minimum inside diameter of 4 inches and sized in not less than 1-inch increments. For semi-circular pipe, unless otherwise indicated, use pipe with a smooth-walled bottom section and an average inside diameter of 4 5/8 inches.

1.c Perforations. Perforate a pipe to provide a minimum water inlet area of 1.4 square inches per linear foot of pipe and, unless otherwise specified, as follows:

• Cut perforations cleanly so as not to restrict the flow of water.

• Provide either circular or slotted perforations, except do not use slotted perforations in smooth walled pipe.

• For circular perforations, provide holes with a nominal diameter not less than 3/16 inch or greater than 3/8 inch. Also, provide similar rows of perforations on both sides of the pipe's vertical centerline, with the lower most rows separated by an arc of 60 degrees minimum.

• For slotted perforations, provide slots not exceeding 1/8 inch wide and a length not more than 10% of the average inside circumference for 4 -inch to 8 -inch diameter pipe and not exceeding 2 1/2 inches for pipes larger than 8 inches. Additionally, center the slots in the corrugation valleys and at maximum 120 degree intervals about the pipe circumference.

1.d Strength Test. As specified, except for plastic pipe test using the parallel plate load test, according to ASTM D2412.

1.e Infiltration Rate. For perforated or porous pipe, provide a minimum infiltration rate of 10 (gallons per minute) per linear feet of pipe, as determined according to AASHTO M 176M.

1.f Pipe Length. Flexible plastic pipe, 6 inches or less in diameter, may be supplied in specified coiled lengths or standard increments agreeable to the Department. The use of long coils, 3,000 feet to 4,000 feet in length, is allowed, provided placement is by equipment r ecommended by the manufacturer and the pipe is not stretched or damaged during handling or placement. Furnish flexible plastic pipe, larger than 6 inches in diameter, and all sizes of rigid pipe in maximum lengths of 20 feet. Furnish lengths not less than 99% of the stated quantity. Measure with any suitable device accurate to 1/4 inch in 10 feet (0.2%) while the pipe is stress-free and at rest on a flat surface in a straight line.

1.g Plastic Pipe. Furnish extruded or molded plastic pipe made of high density, flexible plastic. Furnish pipe that is permanently marked, stenciled, or labeled with manufacturer's name, pipe trade name, or type, average size the specification designates, the plant designation code, and the date of manufacture all at intervals of no more than 10 feet.

AASHTO M 294 (pipes 12 inches through 15 inches), modified as follows:

• The Department will determine the lot size for acceptance.

• Minimum pipe stiffness for pipes 4 inches through 10 inches to be 30 pounds per square inch at 10% deflection, when tested according to ASTM D2412. Minimum pipe stiffness for pipes 12 inches through 15 inches to be 45 pounds per square inch at 5% deflection and 40 pounds per square inch at 10% deflection, when tested according to ASTM D2412.

as follows:

• Minimum pipe stiffness for pipes 4 inches through 10 inches, 35 pounds per square inch at 5% deflection, when tested according to ASTM D2412. Minimum pipe stiffness for pipes 12 inches through 15 inches, 45 pounds per square inch at 5% deflection, when tested according to ASTM D2412.

• Capable of being flattened to 40% of the original pipe O.D. without splitting, cracking, or breaking

• Minimum pipe stiffness for pipes 4 inches through 10 inches, 35 pounds per square inch at 5% deflection, when tested according to ASTM D2412. Minimum pipe stiffness for 12 inch pipe, 45 pounds per square inch at 5% deflection, when tested according to ASTM D412.

• Capable of being flattened to 60% of the original pipe O.D. without splitting, cracking, or breaking .

• Smooth or corrugated top and a smooth semicircular bottom.

• Minimum pipe stiffness (PS), 35 pounds per square inch at 5% deflection, when tested according to ASTM D2412.

• Capable of being flattened to 40% of the original pipe outside -to-outside height for PVC or 60% for ABS without splitting, cracking, or breaking.

Type IIIA; AASHTO M 218; AASHTO M 274; and AASHTO M 289.

9.a General. Use prefabricated pavement base drains consisting of an inert, plastic core, designed to carry water flow, wrapped in geotextile fabric for filtering purposes. Select from a manufacturer listed in Bulletin 15.

9.b Backfill. As indicated, fine aggregate, Type A, except limestone sand, Section 703.1.

9.c Core Materials. An inert, plastic material resistant to commonly encountered chemicals and substances, having the following properties:

• Tensile strength, ASTM D638. 1,200 pounds per square inch, minimum

• Water absorption, ASTM D570. 0.01% after 24 hours

• Fungus resistance, ASTM G21. no growth

• Crush strength, *GRI-GC4. 40 pounds per square inch, minimum

• Flow rate, ASTM D4716. 15 gallons per minute per foot of width, minimum

• Provide a minimum of 6% open core area on the pavement side face of the base drain and a minimum of 3% on the shoulder side face.

• Provide unobstructed inflow through a minimum of 50% of the geotextile area on the pavement side face of the base drain and 12% of the geotextile area on the shoulder side face, when stretched across the face of the core.

* Geosynthetic Research Institute, Drexel University.

9.d Geotextile Fabric. Provide geotextile, non-woven, needle punched, conforming to Table A. Resins are to be virgin materials, unless otherwise approved, and identified as such in the certification statement.

TABLE A Prefabricated Pavement Base Drain - Geotextile Physical Requirements Fabric Properties Test Method Required Value (1)

range, except as noted.

9.e Approval. Approval will be based on certified test data submitted by the manufacturer or testing by LTS, or both, before being listed in Bulletin 15.

9.f Certification and Shipment to Project. Certify each shipment as specified in Section 106.03(b)3. Clearly identify each roll of pavement base drain by affixing a tag or sticker containing the following information:

• Lot number

• Manufacturer's name and address

• Product type and designation

• Product identification including thickness, height, roll length, and roll weight.

• Geotextile designation

9.g Wrapping of the Core. Wrap the geotextile completely around the drainage core with the seam along the length of the drain, on the shoulder side face, and preferably near the midpoint. Fabricate the seam using a non water-soluble adhesive, if adhesive is used. Firmly attach geotextile to the protrusions on the pavement side face of the drainage core and spot -bond on the shoulder side face or submit results of flow tests on the drain under loading with the geotextile unattached, to ensure that the geotextile will not deform under continuous loading to the point where flow capacity is diminished, and the specified minimum flow rate is not achieved.

9.h Splice Connections and Fittings. Provide standard fittings and splice connections along the pavement base drain, as indicated or as directed, of sufficient strength to withstand construction handling and permanent loading. Obtain approval for any nonstandard fittings and connections.

9.i Outlets. Section 615.2

or blast furnace slag sand prepared from Type C, or better, coarse aggregate as specified in Section 703.2; except conform to the size and grading requirements for Type A sand, Section 703.1, with a maximum loss in soundness test not exceeding 20%.

for gravel is not required. Use No. 57 for Type I backfill and No. 8 for Type II backfill.

610.3CONSTRUCTION—As shown on the Standard Drawings and as follows:

Place pavement base drain after the adjacent roadway pavement is constructed, except when it is placed under curb sections or other special locations. Excavate pavement base drain trench without disturbing subbase under the roadway pavement. Join underdrain or base drain to new or existing drainage structures with satisfactory connections. Use fittings with deflection angles of 45 degrees or less. After completing the trench and the lower 2 inches of compacted backfill, lay the pipe and make the joints according to the manufacturer’s recommendations. For perforated pipe, place the perforations down, unless otherwise directed. Lay semicircular pipe with the smooth, circular portion at the bottom. Do not leave trenches open during periods of precipitation or overnight. Seal the upgrade end of pipe underdrain or base drain to prevent entry of foreign material. Complete backfilling after having the pipe inspected by the Inspector-in-Charge.

base drain construction and if indicated for pipe underdrain construction.

to the Representative, in writing, and note any deviation from the plans or from the manufacturer's approved drawings. Upon request by the Representative, have a techni cal representative from the manufacturer present during installation.

so as not to damage or contaminate them. Visually inspect all materials, before placement, to ensure they are free from damage. Damaged drainage material will not be accepted. Store dra inage material on an elevated platform and protect from weather and ultraviolet exposure. Do not remove material from the manufacturer's protective covering until ready to be installed. If material is rerolled and stored, use an approved protective covering equivalent to the manufacturer's original wrapping.

roadway pavement edge as shown on the Standard Drawings . Construct trench without disturbing the pavement structure or subbase. Unless otherwise indicated or directed, provide trench having a width as shown on the Standard Drawings and a depth extending at least 2 inches into the subgrade.

shown on the Standard Drawings. Place the first lift of backfill material simultaneously with drain install to ensure complete contact with the geotextile and the trench wall. Repair any tears in the geotextile according to the manufacturer’s recommendation. If raised core projections protrude from only one side of the drain, place the projections toward the pavement side of the trench. Backfill the trench with fine aggregate, Type A using 9 -inch (maximum) hydraulically compacted lifts. Spray each lift with water at 1.0 gallon per linear foot. Ensure that excavation, drain placement, and backfill operations are performed in sequence, with a minimum amount of trench open at all times. Do not leave trenches greater than 2 inches in depth open overnight. Barricade trenches at all times according to the requirements of 67 PA Code, Chapter 203. If shoulder restoration is indicated, follow applicable specifications and standards to reconstruct the existing shoulder as specified in the contract documents.

restrict flow. Follow the manufacturer's approved connection details. Do not allow backfill material to enter the connector at any point. For drainage cores that splice using male -to-female o verlapping, roll back the geotextile onto the in-place drainage core, make the splice, and rewrap the geotextile over the completed joint. Provide a minimum of 6 inches of geotextile overlap from one section to the next. Install subsurface drain outlet pipe and fittings as specified in Section 615.3, concurrently with the pavement base drain, to establish positive drainage within 24 hours of the beginning of trenching for the installation of a given section of base drain. The Representative may restrict installation of additional sections of base drain until acceptable outlet installations are completed. Ensure transitions are smooth and non-restricting to flow. Do not use “home-made” connections. Install all fittings and connections to preclude soil intrusion into the drainage core or outlet piping and to provide continuity of drainage flow. Install fittings for positive, gravity flow, and outlet the drainage system as indicated or as directed. Fur nish outlet pipes with galvanized wire mesh shields as shown on the Standard Drawings. If the drain is terminated without an outlet, provide a fitting to prevent soil intrusion into the end of the drainage core. Protect all joints and fittings from damage during construction.

610.4MEASUREMENT AND PAYMENT—

For extra-depth pipe underdrain and extra-depth pavement base drain excavation in excess of that shown on the Standard Drawings.

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