ITEM
605 UNDERDRAINS
605.01
Description
605.02
Materials
605.03 Pipe Underdrains Construction
605.04
Construction Underdrains
605.05
Prefabricated Edge Underdrains
605.06 Underdrain Outlets
605.07
Aggregate Drains
605.08 Method
of Measurement
605.09 Basis of
Payment
605.01
Description.
This work consists of constructing unclassified pipe underdrains,
shallow pipe underdrains, deep pipe underdrains, base pipe underdrains,
or rock cut underdrains with or without a filter
fabric, construction underdrains, prefabricated edge underdrains and aggregate drains.
Use
removed or excavated materials in the Work when the material conforms to the
specifications; if not, then recycle or dispose of the material according to 105.16 and 105.17.
Concrete, Class
QC-Misc................................ 499 and 511
Reinforcing
steel...................................................... 509.02
Filter fabric, Type A................................................ 712.09
Backfill
unclassified pipe underdrains, shallow pipe underdrains, deep pipe underdrains,
base pipe underdrains, or rock cut underdrains with or without a filter fabric, construction underdrains and aggregate drains with granular material
consisting of No. 8, 9, or 89 size air-cooled blast furnace slag, limestone, or
gravel. Use granular material with a maximum sodium sulfate soundness loss of
15 percent.
Backfill
prefabricated edge underdrains with granular material
consisting of No. 8 size air-cooled blast furnace slag, limestone, or gravel.
Use granular material with a maximum sodium sulfate soundness loss of 15
percent.
For
605.02.A through 605.02.B, use the pipe of the same size and kind
listed in the Proposal. If the kind of pipe is not specifically itemized
in the Proposal, use types as listed below.
A. Pipe for 605 Rock Cut Underdrains.
Corrugated polyethylene
drainage tubing (perforated)... 707.31
Smooth-wall polyvinyl
chloride underdrain pipe………707.41
Polyvinyl chloride
corrugated
smooth interior pipe
.... (perforated
according to 707.31).........................
707.42
Polyvinyl chloride solid
wall pipe
.... (perforated
according to 707.31).........................
707.45
B. Pipe for 605 Unclassified Pipe Underdrains, Shallow Pipe Underdrains,
Deep Pipe Underdrains, Base Pipe Underdrains
Perforated concrete pipe...........................................
706.06
Concrete drain tile, extra
quality............................... 706.07
Perforated vitrified clay
pipe.................................... 706.08
Clay drain tile, extra
quality..................................... 706.09
Corrugated steel underdrains, Type III.................... 707.01
Corrugated polyethylene
.... drainage
tubing, (perforated)............................... 707.31
Polyvinyl chloride plastic
pipe................................. 707.41
Corrugated aluminum alloy
pipe and
.... underdrains, Type
III.......................................... 707.21
If the specified size
of the underdrains a 6-inch (150 mm) shallow pipe underdrain or base pipe underdrain
and the kind of pipe material is not specifically itemized, then the Contractor
may use 4-inch (100 mm) 707.31 perforated
corrugated polyethylene drainage tubing.
C. Pipe for 605 Construction Underdrains
6 inch (150 mm) Corrugated
polyethylene drainage
... tubing (perforated).............................................
707.31
D. Pipe for 605 Prefabricated Edge Underdrains.
Use pipe conforming to 712.10.
605.03 Pipe Underdrains
Construction.
Construct underdrains as follows:
A. Excavation. Excavate trenches to such dimensions allowing
ample room for construction. Construct the trench width to at least 14
inches (350 mm) for 6-inch (150 mm) diameter underdrains,
and to at least 10 inches (250 mm) for 4-inch (100 mm) diameter underdrains. Excavate the trench walls as vertical as
possible, and excavate bell holes to allow proper placing of the underdrain. Remove obstructions encountered while
excavating for the underdrains.
Excavate trenches
measured vertically from the subgrade to the bottom of the trench at a depth of
18 inches (450 mm) for base pipe underdrains, 30
inches (760 mm) for shallow pipe underdrains, and 50
inches (1270 mm) for deep pipe underdrains unless
otherwise specified in the plans. Furnish a depth of 30 inches (760 mm)
for construction underdrains unless otherwise
specified in the plans. Excavate trenches for unclassified pipe underdrains to the depth specified in the plans.
Excavate trenches to
a depth of 6 inches (150 mm) below the rock, shale or coal depth required in 204.05 for Rock Cut underdrains
unless otherwise specified in the plans.
If underdrains are to be placed within or beneath an
embankment, construct the embankment to the elevation of the top of the
subgrade before trenching for the underdrain.
If filter fabric is
specified, line the underdrain trench with filter
fabric. Place the filter fabric to completely surround the granular
material. Overlap the filter fabric at the top of the trench. Match
the overlap to the trench width. At other seams, overlap filter fabric a
minimum of 12 inches (0.3 m).
B. Laying Underdrain.
Lay the underdrain true to line and grade with close
fitting joints. Place the underdrain in the
center of the trench . Use locking bands or
smooth sleeve type couplers matching the underdrain
material type to join 707.01, 707.31, 707.41,
and 707.21. When bell and spigot underdrain is used, lay it with the bell end facing up
grade. Set the underdrain on a solid bed shaped
to fit the underdrain throughout its entire length.
Make all necessary connections with branches, wyes, tees, transitions, and
bends that match the underdrain material type.
Close the upper ends of underdrains with suitable
plugs.
Lay perforated underdrain so that the perforations are in the bottom half
of the underdrain.
C. Backfilling. Inspect the underdrains
before placing any granular material. Place the granular material for the
full width of the trench around the underdrain, and
extend it to the bottom of the pavement or base as shown on the plans. If
underdrains are placed outside of the pavement or
base area, extend the granular material to within 4 inches (100 mm) of the
finished grade. Fill the remaining depth of the trench with 203 embankment material.
D. Protection. Place the pavement over the underdrain
trench within 90 days after placing the trench backfill. If the trench
remains open for longer than 90 days, remove and replace backfill contaminated
by soil.
605.04 Construction Underdrains. Construct
construction underdrains as follows:
A. Excavation. Construct the trench width to at least
10 inches (250 mm) with a minimum of 2 inches (50 mm) on each side of the underdrain. Excavate the bottom of the trench to
allow proper placing of the underdrain. Remove
obstructions encountered while excavating for the underdrains.
B. Trench Depth and Backfill. Construct the trench depth to that shown on the
plans or 30 inches (750 mm). Backfill the trench with
granular material for the full width of the trench and to the full height of
the trench.
C. Outlet. Outlet the construction underdrains
as possible into the ditch or drainage structures. There is no change in
pipe types for the outlet.
D. Removal. Construction underdrains
are not to be removed at any time. If the construction practice used
requires the construction underdrains to be removed
then install replacements as soon as possible.
605.05 Prefabricated Edge Underdrains. Install
the prefabricated edge underdrains against the
outside wall of a 4-inch (100 mm) trench, and backfill the trench adjacent to
the pavement with granular material. Place the granular material in one
or more lifts with a vibratory compactor run over the final lift to compact the
granular material before placing the asphalt plug. Place the first layer
of the granular material simultaneously with the trenching operation to hold
the edge underdrains flush against the trench wall.
Splice
the prefabricated edge underdrains as required before
placing in the trench, using material furnished by the manufacturer and
according to the manufacturer’s directions. Require the manufacturer to
furnish all material required for the splices, and furnish any equipment
required for splicing. Construct splices to prevent separation of
adjoining sections of the prefabricated edge underdrain
panels.
605.06 Underdrain Outlets.
Construct pipe outlets concurrently with underdrains.
Provide all outlets on the slope with a precast reinforced concrete outlet
according to Item 611 and a tied concrete block mat
type 1 grouted according to 601.12.
Construct
the underdrains outlets according to Item 611 using outlet fittings. Require the manufacturer to
supply outlet fittings that transition between the underdrains
and the outlet pipe. Provide smooth-lined or corrugated outlet fittings. Have
the underdrains and outlets on fractured slab
projects, such as crack and seat, rubblized, or break and seat projects, in
place and functional before fracturing the existing pavement.
Mark
all underdrain outlets with a wooden lath prior to
final seeding. Clean all debris from the outlets after final seeding.
605.07 Aggregate Drains. Construct the aggregate
drains after the completion of granular pavement courses.
A. Excavation. Excavate trenches for aggregate drains to a
minimum width of 12 inches (0.3 m) and to the depth shown on the plans.
Slope the bottom of the trench to drain and keep it free from loose particles
of soil. Excavate the trench to furnish a clean exposure of the granular
pavement courses.
B Placing and
Backfilling. Use granular material for the drains.
Place the aggregate to a minimum depth of 8 inches (200 mm) above the bottom of
the trench. The remaining depth of the trench backfill
with suitable embankment material according to Item 203.
605.08 Method of Measurement. The
Department will measure Unclassified Pipe Underdrains,
Shallow Pipe Underdrains, Deep Pipe Underdrains, Base Pipe Underdrains
Construction Underdrains, Rock Cut Underdrains, and Prefabricated Edge Underdrains
by the number of feet (meters) completed and accepted in place, measured from
end to end of each run.
The
Department will measure Aggregate Drains by the number of feet (meters)
completed and accepted in place, measured along the bottom of the trench.
605.09 Basis of Payment. The Department will pay
for pipe outlets under 611.
The
Department will pay for precast reinforced concrete outlets under 611 Precast Reinforced Concrete Outlet.
The
Department will pay for tied concrete block mats type 1 grouted under 601 Tied Concrete Block Mat.
Rock
Cut Underdrains are placed in rock and all required
trenching in the rock is included under Rock Cut Underdrain.
The
Department will pay for accepted quantities at the contract prices as follows:
Item
Unit
Description
605
Foot
(Meter)
____ " (____ mm) Unclassified Pipe
Underdrains
605
Foot
(Meter)
6" (150 mm) Construction Underdrains
707.31
605
Foot
(Meter)
____ " (____ mm) Shallow Pipe Underdrains
605
Foot
(Meter)
____ " (____ mm) Deep Pipe Underdrains
605
Foot
(Meter)
____ " (____ mm) Base Pipe Underdrains
605
Foot
(Meter)
Aggregate Drains
605
Foot
(Meter)
____ " (____ mm) Rock Cut Underdrains
605
Foot (Meter)
____ " (____ mm) Prefabricated Edge
Underdrains