SECTION 605: D R A I N S
605.1 Description
This Work consists of construc ting underdrains, french drains, vertical drains, and drain outlets.
605.1.1 Definitions
Drain Outlet Lateral. A Drain Outlet Lateral is a non-perforated pipe placed in an u nlined, backfilled trench. French Drain. A French Drain is a non-vert ical, rectangular, prism-shaped, s ubterranean water-collector drainage system consisting of open-graded granu lar Material wrapped in geotextile fabric (“drainage blanket”) and a perforated collect or pipe at the drainage blanket's lowest elevation. Underdrain. An Underdrain is a collector drainage system typically located under pavement sections. An Underdrain system consists of a perforated collec tor pipe placed in a geotextile- lined, shallow, narrow trench that is then backfilled with untr eated, open-graded Base Course. Vertical Drain. A Vertical Drain is a vertical, rectangular, prism-shaped, sub terranean, water-collector drainage system consisting of open-graded granu lar Material wrapped in geotextile fabric.
605.2 Materials
605.2.1 Pipe
605.2.1 1 Polyvinyl Chloride Pipe
The Contractor shall provide PVC pipe in accordance with the fo llowing: 1. ASTM D 1785; 2. ASTM D 2464; 3. ASTM D 2467; and 4. ASTM D 2564. The Contractor shall provide perforations and slots in accordan ce with AASHTO M 175, except provide perforations with a diameter of 0.19 in, unless otherwise specified in the Contract.
605.2.1 2 Polyethylene Pipe
The Contractor shall provide polyethylene pipe in accordance wi th AASHTO M 252, AASHTO M 294, and ASTM D 3350.
605.2.1 3 Metal Pipe
The Contractor shall provide me tal pipe in accordance with Sect ion 570, “Pipe Culverts.”
605.2.2 Drainage Geotextiles
The Contractor shall provide drainage geotextiles for Underdrai ns in accordance with Section 605: Drains Page 635 Section 604, “Soil and Drainage Geotextiles.”
605.2.3 Granular Materials
The Contractor shall provide granular backfill in accordance wi th Section 303, “Base Course,” for open graded Base Course, or as specified in the Co ntract.
605.2.4 Hardware Screen
The Contractor shall provide gal vanized steel or stainless stee l hardware screen for drain outlets with one (1) inch nominal mesh openings. The Contracto r shall provide galvanized connecting hardware.
605.2.5 Precast Headwall
The Contractor shall provide pr ecast headwall with hardware scr een as per Contract.
605.3 Construction Requirements
605.3.1 Placement of Drainage Geotextiles
The Contractor shall place drainage geotextiles in accordance w ith Section 604, “Soil and Drainage Geotextiles.” The Contractor shall connect and maintain overlaps of geotextil es so that the drainage geotextile covers the drain for the entire length and has no br eaks or holes.
605.3.2 Placement of Pipe
The Contractor shall place perforated pipe with the perforation s down, unless otherwise specified in the Contract. The Contractor shall join pipe sect ions securely with the appropriate couplings, fittings, or bands as recommended by the manufacture r for the specific application. The Contractor shall place non-perforated pipe with the bell-e nd upgrade. The Contractor shall close upgrade ends with concrete plugs to prev ent entry of soil Materials.
605.3.3 Placement of Open-Graded Backfill
After the Department inspects a nd approves the pipe installatio n, the Contractor shall place granular Material in layers no more than 12 inches thick and compact after placement of each layer with a steelwheeled, self-propelled roller that will provide good consolidation without excessive breakage of the aggregate, to the satisfactio n of the Project Manager. The Contractor shall not displace pipe or geotextile.
605.3.4 Placement of Impermeable Material
If the Contract requires the Contractor to place an impermeable Material around the drain system, the Project Manager must approve the Material. The Contractor shall place the impermeable Material in no more than six (6) inch layers of loose thickness. The Contractor shall compact each layer of impermeable Material to at least 95% of maximum density in accordance with AASHTO T 180 (M odified Proctor), Method D (TTCP Modified).
605.3.5 Outlet Laterals
The Contractor shall place non-perforated pipe in the unlined t rench with ends firmly joined as recommended by the manuf acturer for the specific appl ication. After the Department inspects a nd approves the pipe installatio n, the Contractor shall backfill the trench with approved Material in layers and compac t in accordance with Section
206.3 1, “Construction Requirements, General.”
605.3.6 Exposed Drain Outlets
The Contractor shall provide hardware screens for openings of e xposed drain outlets. The Contractor shall mechanically secure the screen along the c ircumference of the outlet without damaging the drain. The Contractor shall provide preca st concrete headwall with hardware screen when specified in the Contract.
605.4 Method of Measurement—Reserved
605.5 Basis of Payment
Pay Item Pay Unit Underdrains Linear Foot Vertical Drains Linear Foot French Drains Linear Foot The Department will pay for excavation in accordance with Secti on 206, “Excavation and Backfill for Culverts and Minor Structures.”
605.5.1 Work Included in Payment
The following Work and items will be considered as included in the payment for the main item(s) and will not be measured or paid for separately: 1. All open-graded aggregate; 2. Geotextiles; 3. Pipe; 4. Precast concrete headwall with hardware screen (rodent shiel d); 5. Hardware; and 6. Compaction. Section 606: Metal Barrier, Cable Barrier and Concrete Wall Barrier Page 637