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1. SCOPE
The work shall consist of furnishing and installing tubing and the necessary fittings and appurtenances as shown on the drawings and as outlined in this specification.
2. MATERIALS
Corrugated polyethylene tubing and fittings shall conform to the material requirements as outlined in Material Specification 548.
When perforations are specified, the water inlet area shall be a minimum of one (1) square inch per lineal foot of tubing. The inlets shall be either 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 which provides adequate support to the tubing and does 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 surfaces or rocks). All special handling requirements of the manufacturer shall be strictly observed. Special care shall be taken to avoid impact when the pipe must be handled at temperatures of 40o 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 a period of fifteen 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 materials shall be placed in the bottom of the trench just prior to the laying of the tubing. 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 as 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 one-fourth of the outside circumference of the tubing. After the tubing is placed in the excavated groove, it shall be capped with friable materials from the sides of the trench. The friable material shall be placed around the tubing, completely filling the trench to a depth of not less than three (3) inches over the top of the tubing. For materials to be suitable it must not contain hard clods, rocks, frozen soil, or fine material which 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 prior to the completion of construction activities for that day.
6. PLACEMENT AND JOINT CONNECTIONS
All tubing shall be installed to grade as shown on the drawings.
After placement of the tubing in the trench and blinding, sufficient time shall be allowed for the tubing to adapt to the soil temperature prior to backfilling.
Maximum allowable stretch of the tubing shall be five (5) percent. Special precautions must be implemented on hot, bright days to insure 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 will be 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 will be determined to the nearest foot of length measured along the centerline of the installed tubing. Payment for each kind and size of tubing will be made at the contract unit price for that kind and size of tubing. Such payment will constitute 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 will be made at the contract unit price(s) for that 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 will be 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 will be made at the contract unit price for the kind, size, and class. Such payment will constitute 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 will be made at the contract prices for those items.
All Methods The following provisions apply to all methods of measurement and payment. Compensation for any item of work described in the contract but not listed in the bid schedule will be 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.