605UNDERDRAINS

New Hampshire Department of Transportation Standard Specifications – 2016 Description

1.1This work shall consist of furnishing (unless pipe is provided) and installing underdrains at the locations shown or ordered.

Pipe, common structure excavation, support membrane, graded aggregate, sand cushion, and backfill where specified shall be included in this work. 1.1.1 Furnishing and installing underdrain flushing basins as shown on the plans or ordered shall also be included in this work.

1.2Aggregate underdrain shall consist of furnishing and installing support membrane, graded aggregate, pipe, if ordered,

common structure excavation, and backfill as necessary. Materials

2.1Perforated corrugated steel pipe and coupling b ands shall conform to the applicable requirements of AASHTO M 36, Type

III. The minimum allowable metal thickness of 6 ” underdrain pipe shall be 0.052” ; the minimum allowable metal thickness in underdrain pipe larger than 6” shall be 0.064”.

2.2Perforated corrugated aluminum pipe and coupling bands shall conform to the applicable requirements of AASHTO M 197.

2.3Polyvinyl Chloride (PVC).

2.3.1 Manufacturers of Polyvinyl Chloride (PVC) pipe must participate in and maintain compliance with, the AASHTO “ National Transportation Product Evaluation Program” (NTPEP) that audits producers of plastic pipe. A certificate of compliance, as required by 106.04, shall be provided for each shipment. 2.3.2 Smooth-wall perforated and un-perforated polyvinyl chloride pipe, bends and cleanouts shall conform to AASHTO M 278. Perforated polyvinyl chloride profile wall pipe shall conform to AASHTO M 304. 2.3.3 Basis of acceptance and test requirements of polyvinyl chloride pip e shall conform to AASHTO M 278 or AASHTO M 304 for the respective type of pipe.

2.4Polyethylene.

2.4.1 Manufacturers of polyethylene pipe must participate in and maintain compliance with, the AASHTO National Transportation Product Evaluation Progra m (www.ntpep.org) that audits producers of polyethylene pipe a Certificate of Compliance as required by 106.04 shall be provided for each shipment. 2.4.2 Polyethylene drainage tubing 6” in diameter shall conform to AASHTO M 252, TypeS, with either Class 1 or Class 2 perforations. Perforated corrugated polyethylene pipe of nominal sizes 12 to 36” diameter shall conform to AASHTO M 294, with Class 1 perforations. Lengths for all sizes shall not exceed 20 ft. 2.4.3 Basis of acceptance and test requirements of polyethylene pipe shall conform to AASHTO M 252 or AASHTO M 294 for the respective type of pipe. The approval criteria can be obtained from the Bureau of Materials and Research. A certificate of compliance, as required by 106.04, shall be provided for each shipment.

2.5Pipe Underdrain, Materials Per Contractor's Option.

2.5.1 When the item reads 6” pipe underdrain (Contractor’s option), it shall be the Contractor's option whether he furnishes perforated corrugated steel pipe, perforated corrugated aluminum pipe, perforated polyvinyl chloride pipe or perforated corrugated polyethylene drainage tubing.

2.6Sand cushion shall be so graded that 90 to 100 percent by weight will pass a 1/2 ” sieve, and not more than 12 percent will

pass a No. 200 sieve.

2.7Underdrain backfill shall meet the requirements of 209.2.1.

2.8Molded pull boxes for underdrain flushing basins shall conform to 614.2.6.

2.9Aggregate for aggregate underdrain shall conform to Table 703-1, Standard Size #4.

2.10Support membrane shall be non-woven geotextile and conform to Item 593.131 - Geotextile, Subsurface Drainage, Class 3,

Non-woven. Construction Requirements

3.1Trenches shall be excavated to the dimensions and grade shown or ordered. A mini mum 2 ” sand cushion in common

excavation and a 6” sand cushion in rock excavation shall be placed in the bottom of the trench for its full width and length to the grade of the bottom of the pipe.

New Hampshire Department of Transportation Standard Specifications – 2016

3.2Perforated pipe shall normally be placed with the perforations down, and sections shall be securely joined with the appropriate

couplings, fittings, or bands.

3.3After the pipe installation has been inspected and approved, underdrain backfill material shall be placed to a height of 12 ”

above the top of the pipe, care being taken not to displace the pipe. The remainder of the backfill material shall then be placed to the required height and compacted in lifts not to exceed 12”.

3.4Pipes shall be laid with 45-degree bends where changes in direction are indicated on the plans.

3.5Except at structures, upgrade ends of all underdrain pipe installations shall be closed with suitable plugs to prevent entry of

soil material.

3.6Flushing Basins.

3.6.1 Flushing basins shall be installed approximately 2 ft. beyond the break in the shoulder and in such manner as to allow the molded pull box to be set within the slope limits. 3.6.2 Any excavation required to install flushing basins shall be done in accordance with 3.1. 3.6.3 Additional 6” un-perforated pipe shall be added to the long 1/8 bend to bring the riser to the required el evation. 3.6.4 After the fitting and 6 ” riser pipe installation has been inspected and approved, underdrain backfill material shall be placed and properly compacted to a height which will allow for the proper installation of the cleanout and molded pull bo x. The remainder of the backfill and base course necessary shall then be placed to the required height and compacted. Care shall be taken to prevent backfill material from entering the riser pipes.

3.7Aggregate Underdrains.

3.7.1 Trenches shall be excavated to the dimensions shown or ordered. Type 1 aggregate underdrain shall have a 6 ” by 10 foot section of pipe at the outlet end of each section of underdrain. Type 2 shall include pipe of the specified diameter throughout. 3.7.2 Non-woven support membrane shall be installed so as to minimize the number of fabric seams within the trench section. Seams shall be constructed by overlapping the fabric at least 12” and folding to create a joint which will ensure that soil infiltration will be retarded. 3.7.3 Aggregate shall be placed within the typical section as shown in a manner that will maintain the fabric integrity. Punctures created by aggregate, equipment, tools or improper handling shall be patched by placing fabric at least 12 ” beyond the puncture limits on the outside of the typical section. 3.7.4 Pipe, as required, shall be laid to grade as ordered. 3.7.5 Backfill shall be placed and tamped in the areas outside and adjacent to the aggregate underdrain so that the shape of the typical is maintained. Sharp pieces of rock shall not be placed immediately adjacent to the fabric. 3.7.6 When rock is encountered, sharp projections of solid rock shall be removed within the typical section, primarily at the bottom of the trench.

3.8Workmanship. Underdrain 12” and above that is also utilized as part of a drainage run shall be video inspected in accordance

with 603.3.7. Method of Measurement

4.1Underdrains will be measured by the linear foot to the nearest 0.1 foot along the centerline of the pipe.

4.1.1 Aggregate underdrain will be measured by the linear foot, to the nearest 0.1 of a foot along the centerline of the aggregate underdrain.

4.2Backfill or cushioning material furnished will be subsidiary.

4.3Underdrain flushing basins will be measured by the number of units installed.

4.3.1 Each unit shall include all required riser pipe, 45 ° wye, long bend, cross pipe, cleanout pull box and backfill material as required.

4.4Video inspection required under 3.8 will be measured in accordance with 603.4.

Basis of Payment

5.1The accepted quantities of underdrain of the type specified will be paid for at the Contract unit price per linear foot in pl ace,

including common structure excavation, sand cushion and backfill. 5.1.1 Payment will not be made for 45 degree bends.

New Hampshire Department of Transportation Standard Specifications – 2016 5.1.2 Rock excavation will be paid for under Item 206.2.

5.2The accepted quantity of underdrain flushing basins will be paid for at the Contract unit price per each com plete in place,

including riser pipe, 45O wye, long bend, cross pipe, cleanout pull box, common structure excavation, and backfill.

5.3The accepted quantities of aggregate underdrain of the type specified will be paid for at the Contract unit price per linear foot

in place, including support membrane, graded aggregate, pipe, if ordered, common structure excavation, and backfill. 5.3.1 Payment will not be made for fabric used for patching. 5.3.2 Rock excavation required will be paid for as provided in 5.1.2.

5.4Video inspection required under 3.8 will be paid for as provided for in 603.5 .

Pay items and units: 605.1_ _in Perforated Corrugated Steel Pipe Underdrain Linear Foot 605.4_ _in Perforated Polyvinyl Chloride Pipe Underdrain Linear Foot 605.5_ _in Perforated Corrugated Polyethylene Pipe Underdrain Linear Foot

605.79Underdrain Flushing Basins Each

605.81A _in Aggregate Underdrain Type 1 Linear Foot

605.82ABC _in Aggregate Underdrain Type 2, With Pipe Linear Foot

605.84015 1-1/2” PVC Plastic Horizontal Drains Linear Foot

605.906 6” Pipe Underdrain (Contractor’s Option) Linear Foot

Notes: A = Width of Underdrain 1 = 18” 2 = 24” 3 = 30” 4 = 36” 5 = 48” 6 = 16” B = Type of Material 1 = Perforated Corrugated Steel 2 = Blank 3 = Perforated Corrugated Aluminum 4 = Perforated Polyvinyl Chloride 5 = Perforated Corrugated Polyethylene C = Diameter of Pipe 1 = 6” 2 = 12” 3 = 18” 4 = 24” 5 = 4” 8 =8” Examples:

311 30” Aggregate Underdrain Type 2, with

Perforated Corrugated Steel 6” Pipe Linear Foot

6 6” Pipe Underdrain. (Contractor's Option) Linear Foot

New Hampshire Department of Transportation Standard Specifications – 2016

Description

This work shall consist of furnishing and installing guardrail, anchorages, terminal units, concrete barriers, and pipe handrails

of the type specified at the locations shown on the plans or as ordered. 1.1.1 Resetting of existing guardrail shall be included in this work. 1.1.2 Temporary guardrail, t emporary concrete barrier, and temporary impact attenuators shall consist of furnishing, installing, maintaining, relocating and removing as specified. 1.1.3 Any excavation required for this work is subsidiary to the item except as provided for in 606.5.8 Materials

Wood Posts, Offset Blocks, and Rails.

2.1.1 Wood posts shall be treated in accordance with 2.2, sound and reasonably straight. The ends shall be cut square or as indicated. Posts with hollow knots, open or plugged holes, or season checks exceeding 1/4” in width will be rejected. 2.1.1.1 Guardrail posts, offset blocks and wood rails shall be made of timber with a st ress grade of 1,200 psi or more for extreme fiber in bending in accordance with AASHTO M 168. All cuts and holes shall be made before preservative treatment. 2.1.1.2 Wood rails shall be treated in accordance with 2.2, straight and sound, free from loose knots and other defects, and shall be surfaced on all sides. 2.1.2 Synthetic offset blocks for guardrail shall be a product as listed on the Qualified Products List. They shall be made of synthetic materials, recycled preferred and shall meet the criteria of NCHRP 350 Test Level 3.

Preservative Treatment.

2.2.1 All wood posts, blocks and rails shall be treated with preservative materials conforming to the requirements of AASHTO M 133. 2.2.2 The type of treatment shall be one of the following: Treatment Minimum net retention, Pounds per cubic foot Type A Pentachlorophenol 0.60 Dry Salts Water-Borne Preservative 0.40 2.2.3 All wood posts and rails shall be treated after sawing and drilling or retreated after drilling in accordance with AASHTO M 133.

Structural Shape Posts.

2.3.1 Structural shape steel posts shall conform to ASTM A 36 and shall be galvanized after fabrication to meet the requirements of AASHTO M 111. 2.3.2 Offset blocks for steel post assemblies shall be made of synthetic materials in accordance with 2.1.2.

Rails and Fittings for Beam Guardrail.

2.4.1 Rails and fittings shall be as shown in the current edition A Guide to Standardized Highway Barrier Hardware, AASHTO – AGC- - ARTBA Joint Cooperative Committee. Galvanized steel rail elements, terminal sections, bolts, nuts, and other fittings shall conform to AASHTO M 180 (except that paragraph 11, Marking, shall not apply), Type II, Class A. Galvanized steel rail elements and terminal sections shall be treated with a solution of sodium dichromate or other approved chemical solutions so as to prevent or reduce storage stain. 2.4.1.1 Miscellaneous steel hardware not shown in A Guide to Standardized Highway Barrier Hardware, AASHTO – AGC- - ARTBA Joint Cooperative Committee designation shall conform to ASTM A 36 and A 500 as appropriate. Ha rdware shall be galvanized, after all fabrication, in accordance with AASHTO M 232. 2.4.2 Steel rail elements shall be shop punched to allow for 6 ft. – 3” post spacing or as required. Where the rail is on a curve having a radius of 150 ft. or less, the r ail shall be shop curved. The splice shall make contact throughout the area of the splice. Guardrail parts furnished under this specification shall be interchangeable with similar parts, regardless of the source of manufacture. 2.4.3 The post bolt and connection shall withstand a 5,000 lbs. pull in either direction.