6-28 SECTIO N 605 – UNDERDRAINS 605.0 1 DESCRIPTION . This work shall consist of constructing drainage systems using underdrains, underdrain outlets, flushing basins, and risers. 605.0 2 MATERIALS . Materials shall meet the requirements of the following subsection s: Granular Backfill for Structures ................................ ................................ ................. 704.08 Drainage Aggregate ................................ ................................ ................................ ...704.16 Corrugated Polyethylene Pipe (CPEP) ................................ ................................ ......710.03 Polyvinyl Chloride (PVC) Plastic Pipe ................................ ................................ ......710.0 5 Corrugated Steel Pipe, Pipe Arches , and Underdrains ................................ .............. 711.01 Corrugated Aluminum Alloy Pipe, Pipe Arches, and Underdrains ........................... 711.02 Gray Iron Castings ................................ ................................ ................................ .....715.01(b) Geotextile for Underdrain Trench Lining ................................ ................................ ..720.05 If the Contract does not specify a particular type of underdrain or carrier pipe, the Contractor may furnish underdrain and carrier pipe of the diameter indicated and in any one of the following material s:
a.Corrugated steel
b.Corrugated aluminum alloy
c.Corrugated polyethylene
d.PVC plastic Each system of underdrain, carrie r pipes, and underdrain risers shall be constructed of the same material . 605.0 3 PROTECTIO N OF MATERIALS . Corrugated polyethylene or PVC plastic pipe stored on the job site prior to use shall be protected from pr olonged exposure to sunlight. The Engineer may require impact or other strength tests of the pipe prior to installation when ultraviolet light degradation is suspected. 605.0 4 INSTALLATION .
a.Excavation . Trenches for underdrain shall be excavated to the dimensions and grade shown on the Plans or as directed by the Engineer. The surface of the trench shall be prepared to a smooth condition free of debris, depressions, or obstructions which may damage the geotextile. 6-29 Trenches for carrier pipe shall be excavated to a width 24 inches greater than the inside diameter of the pipe. Proper bedding material shall be provided where excavation is in solid rock or other unyielding material .
b.Placing Geotextile . The geotextile fabric shall be placed loosely with no wrinkles or folds. Care shall be taken to ensure direct contact with the soil such that there are no voids between the geotextile and the trench. The geotextile shall be overlapped a minimum of 12 inc hes at the top of the trench . Additional overlap or anchoring may be required as determined by the Engineer. The upstream geotextile shall be overlapped over the downstream. Drainage aggregate shall be placed to a depth of 6 inches to provide a bed and uni form slope for underdrain pipe placement.
c.Placing Underdrain . The underdrain pipe shall be placed in the center of the trench and firmly embedded in the drainage aggregate . Placing shall be started at th e outlet end and proceed toward the inlet end . The underdrain shall be placed with the perforations down, unless otherwise directed by the Engineer. The joints between section s shall be made by fitting the ends as tightly as practical. Corrugated steel or aluminum alloy underdrain shall be joined with an approved coupling. Polyethylene or PVC plastic underdrain shall be joined with approved fittings. The inlet ends of all under drain pipe installations shall be closed with suitable plugs to prevent entry of soil material . Underdrain flushing basins, consisting of corrugated steel or aluminum alloy pipe of the length and diameter shown on the Plans and a cast iron cover , shall be installed at locations shown on the Plans or as directed by the Engineer. Underdrain risers shall be installed as shown on the Plans or as directed by the Engineer.
d.Placing Carrier Pipes . Carrier pipes used in an underdrain system shall be placed on a firm bed and joined in the same manner as underdrain . Non-perforated pipe shall be used for carrier pipes .
e.Backfill . After an underdrain pipe installation has been inspected and approved, material meeting the requirements of drainage aggregate shall be placed to a height of 12 inches above the top of the underdrain and the layer compacted. Care shall be taken not to disp lace the underdrain pipe. The remainder of the backfill material shall be placed in uniform layers of not more than 6 inches in thickness and thoroughly compacted by use of air or mechanical tampers. After inspection and approval of a carrier pipe installa tion, the trench shall be backfilled with suitable material placed in layers not more than 6 inches in thickness and thoroughly compacted. Unless otherwise specified, this material shall be from trench excavation. 6-30 The backfill material shall not be place d directly in the trench by dumping from haul vehicles or by pushing material into trenches by bulldozers, graders, or other equipment . Placing shall be limited to the use of hand shovels, backhoes, front end loaders, or other similar types of equipment as approved by the Engineer.
f.Flushing . Prior to the acceptance of the project , each underdrain system shall be thoroughly flushed with water to remove any accumulation of silt, sand, or other debris . 605.0 5 METHO D OF MEASUREMENT . The quantity of the specified size of Underdrain or Underdrain Carrier Pipe to be measured for payment will be the number of linear feet installed in the complete and accepte d work . When it is necessary to cut underdrain or carrier pipe in the field, the quantity of underdrain or carrier pipe to be measured for payment will be the length necessary, rounded up to the next whole foot increment. The quantity of Underdrain Flushing Basin to be measured for payment will be the number of units installed in the complete and accepted work including the corrugated pipe and the cast iron cover. 605.0 6 BASIS OF PAYMENT . The accepted quantities of each type and size of Underdrain or Underdrain Carrier Pipe will be paid at the respective Contract unit price per linear foot. Underdrain Flushing Basins will be paid at the respective Contract unit price for each. U nderdrain used for vertical stand pipes at flushing basin locations or risers will be paid as Underdrain Carrier Pipe. Payment will be full compensation for fabricating, furnishing, transporting, handling, and placing the material specified, including coup ling bands and fittings, drainage aggregate , geotextile fabric, and the necessary backfill material to an elevation 7 feet above the flowline, and for furnishing of all labor, tools, equipment , and incidentals necessary to complete the work . Excavation for all underdrain, carrier pipe, flushing basins, vertical stand pipes, and risers will be paid for as Trench Excavation. Payment will be made under: Pay Item Pay Unit
605.10 06 Underdrain Pipe, 6 Inch ................................ ................................ ............ Linear Foot
605.1 008 Underdrain Pipe, 8 Inch ................................ ................................ ............ Linear Foot 605.1 012 Underdrain Pipe, 12 Inch ................................ ................................ .......... Linear Foot
605.20 06 Underdrain Carrier Pipe, 6 Inch ................................ ................................ Linear Foot
605.2 008 Underdrain Carrier Pipe, 8 Inch ................................ ................................ Linear Foot 605.2 012 Underdrain Carrier Pipe, 12 Inch ................................ .............................. Linear Foot
605.95 00 Underdrain Flushing Basin ................................ ................................ .......Each
6-31 SECTIO N 608 – EQUIPMEN T RENTAL 608.0 1 DESCRIPTION . This work shall consist of furnishing, operating, and supervising the use of equipment for performance of work shown on the Plans, in accordance with these specification s or as directed by the Engineer. 608.0 2 GENERA L REQUIREMEN TS. Equipment shall be maintained in good mechanical condition and shall be operated by capable and experienced operators. Equipment that is to operate on paved surfaces shall be equipped with rubber tires or smooth street plates . Tracked equipment used to draw any other equipment shall be of a type that will not damage the work being done and has sufficient power to operate the drawn equipment effectively. Equipment used under this section shall meet the following specific requirements as to type, size, ca pacity, power, or dimensions . In determining whether a particular piece of equipment is classified as Type I, Type II, or Type III in Subsection 608.02(a) , Subsection 608.02(c) , Subsection 608.02(d) , Subsection 608.02( e), or Subsection 608.02( g), the make and model number shall be referenced against an equipment guide book. Whenever equipment of a certain size is requested by the Engineer and the Contractor supplies a larger size, payment will be fo r the size requested.
a.Bulldozer . Bulldozers shall be of the crawler type furnished with an angle type blade and power operated controls . The machine shall be classified by size as follows:
1.Type I . Type I bulldozers shall have a net engine or flywheel power rating of less than 150 horsepower.
2.Type II . Type II bulldozers shall have a net engine or flywheel power rating of 150 horsepower or greater .
b.Grader . Power grader s shall be self -propelled with pneumatic tire wheels, power -operated controls, and a wheelbase of at least 18 feet.
c.All-Purpose Excavator . All-purpose excavators shall be hydraulic excavators and m ay be self - propelled, truck -mounted, or crawler -mounted. The excavator shall include all attachments necessary to efficiently perform the work for which it is rented. The machine shall be classified as follows:
Source: Vermont Standard Specifications for Construction, 2024 Edition. Pages 802–804 of 1,380.