ITEM 518 DRAINAGE OF STRUCTURES
518.01 Description. This work consists of constructing drainage systems.
518.02 Fabrication. Fabricate scuppers according to Item 513. Select a fabricator that is at least
pre-qualified at level SF. The Department will base final acceptance of all fabricated members on the Engineer’s approval that the fabricated items can be successfully incorporated into the structures. Submit mill test reports for structural steel, steel castings, bronze, and sheet lead certified according to 501.06.
518.03 Materials. Furnish materials conforming to:
Scuppers, structural steel and cast steel ............................................ 513 Metal pipe ............................................. 707 Plastic pipe .......................... 707.33, 707.45 Other metals .......................................... 711 Prefabricated Geocomposite Drain (PGD) ................................. 712.16 Geotextile fabric, Type A ................ 712.09 Reinforced thermosetting resin pipe ...................................... 707.80 Furnish pipe specials of a grade at least as high as the type of pipe specified. Furnish porous backfill consisting of gravel, stone, or air -cooled blast furnace slag, with a No. 57 size gradation according to Table 703.01-1. The sodium sulfate soundness loss shall not exceed 15 percent. Furnish ACBFS conforming to Supplement 1027.
518.04 General. As shown on the plans, connect all parts to new or existing sewers or other
outlets. When installing to superstructure, take into account the deflection of spans under full dead load.
518.05 Porous Backfill. Place porous backfill as shown on the plans. When not shown on the
plans, place backfill at least 2 feet (0.6m) thick behind the full length of abutments, wing walls, and retaining walls. Measure the thickness of porous backfill normal to the abutment or wall face. The Contractor may leave undisturbed rock or shale within 18 inches (0.5 m) of the abutment or wall. Place 2 ft³ (0.23 m³) of bagged No. 3 aggregate at each weep hole to retain the porous backfill. Place the porous backfill for the full width of the trench and extend it to the bottom of the approach slab or base, as shown in the plans. Place porous backfill in loose lifts not to exceed 12 inches. Run a plate compactor or tamper over the top of each lift for consolidation of approximately 85% of original layer thickness. If placed in loose lifts greater than 12 inches, flood the porous backfill at the appropriate moisture content for consolidation of approximately 85% of original layer thickness.
518.06 Prefabricated Geocomposite Drain (PGD). Do not use PGD on Integral Abutments or
above the beam seat elevation on Semi Integral Abutments.
A.Preparation. Prepare the surface of the wall or abutment, on which the PGD is to be placed, to be free of soil, debris, and excessive irregularities that prevent continuous contact between the wall surface and the PGD.
B.Placement. Place PGD strips to provide continuous coverage over the face of the wall. Unroll PGD directly onto the prepared surface. Do not drag the PGD across the ground. Tension the PGD to remove any creases or wrinkles. Do not expose PGD to weather or direct su nlight for longer than 5 days. Place the geotextile fabric side to face toward the backfill or retained soil. Construct the PGD in horizontal or vertical courses. Place the PGD in direct contact with the wall and secure to the surface using either adhesives per manufactures recommendation or nails as follows. Secure with 2 inch (51 mm) or longer concrete nails a long with washers or wood battens of not less than 9 square inches (5887 square mm). Space the concrete nails no more than 3 feet (0.9 m) apart, both horizontally and vertically. Use at least one horizontal row of nails in each horizontal course of PGD, or use at least one vertical column of nails in each vertical course of PGD. Do not affect the drainage area and the downward flow in the drain by the adhesive or fasteners.
C.Splicing and covering. Form horizontal or vertical seams between courses by utilizing the flap of geotextile extending from one course and lapping over the flap on that of the next course. Securely fasten the overlapped flaps with a continuous strip of 3 inch (76 mm) wide, waterproof, plastic tape. Where splices are necessary without a geotextile flap, place and center a 12 inch (0.3 m) wide continuous strip of geotextile over the seam and fasten with continuous strips of 3 inch (76 mm) wide, waterproof, plastic tape. As an alternative method of splicing, either horizontally or vertically, rolls of PGD may be joined together by turning back the geotextile flap at the roll edges and interlocking the drainage core approximately two inches. Fold the flap under and tape it beyond the seam with 3 inch (76 mm) wide, waterproof, plastic tape. Shingle lap the core and fabric in the direction of water flow. To prevent soil intrusion, cover all exposed edges of the PGD core by tucking the geotextile flap over and behind the core edge. Alternatively, a 12 inch (0.3 m) wide strip of geotextile may be used to wrap the edge, taping it to the geotextile side 8 inch es (203 mm) in from the edge with a continuous strip of 3 inch (76 mm) wide, waterproof, plastic tape and folding the remaining 4 inches (102 mm) over and behind the core edge. Caps (bottom, top, or end) provided by the manufactures can also be used according to manufacturer’s instructions. Construct all seams, splices, and caps to prevent the backfill material from entering the PGD.
D.Connecting to Weep Holes and Drainage System . Connect the PGD to the drainage system as shown on the plans or per manufacturer’s recommendations if not shown in the plans. Maintain a positive outlet for the water in the PGD at all locations. Do not seal, block or restrict weep holes with the PGD. If available, use weep hole fittings provided by the manufacturer and installed to the manufacturer’s instructions. If the PGD core is not perforated at the weep hole location, make a hole in the PGD core matching the diameter of the weep hole or larger to accommodate the pipe or fitting. When making holes in the core, do not damage the geotextile fabric. Use manufacturer provided outlet fittings that transition between the PGD and the outlet pipe, and prevent material from entering the outlet pipe. If manufacturer fittings are not available, provide smooth-lined or corrugated outlet fittings according to manufacturer’s recommendations. Fasten and seal outlet fittings to the wall drains according to manufacturer’s recommendations.
E.Repair. Patch or replace damaged PGD. Remove the damaged area and place a PGD patch and splice the edges according to 518.06.C. If the damaged portion is larger than 50 percent of the PGD roll width, cut across the entire width of the roll to remove the damaged portion and splice according to 518.06.C. If damage is limited to tears in the geotextile fabric, place a geotextile patch extending 6 inches (152 mm) beyond the damaged area in all directions or to the edge of the roll, and seal the entire perimeter with 3-inch (76 mm) wide, waterproof, plastic tape. Replace and repair damaged PGD at no additional expense to the Department.
F.Backfilling. Replace or repair any PGD component that is damaged during the backfilling operation. Use hand operated compaction equipment to compact the backfill within 1 -foot (0.3m) of the PGD.
518.07 Pipe. For drain pipe leading down from the superstructure, use either galvanized steel
pipe, 748.06, or plastic pipe, 707.45, or reinforced thermosetting resin pipe, 707.80. Provide specials, elbows, tees, wyes, and other fittings essential for a complete and satisfactory installation of the same material and quality as the pipe. Construct watertight joints of adequate strength. In steel pipe, weld joints or use clamp -type couplings having a ring gasket. In plastic pipe, make joints according to the applicable ASTM standard. In reinforced thermosetting resin pipe, make joints according to manufacturer guidelines and procedures. Securely fasten the pipe to the structure with hanger or clamp assemblies that are galvanized according to 711.02. Place subsurface pipe as shown in the plans. If the plans require drainage pipe in the porous backfill, provide plastic pipe conforming to 707.33. For corrugated metal pipe, perforated specials are not required and the Contractor may make bends with adjustable elbows conforming to the thickness requirements of the pipe specifications.
518.08 Scuppers. Construct secure and watertight connections, including the connections to
adjacent concrete. Provide castings, true to form and dimension. Weld the joints of structural steel scuppers. Galvanize scuppers according to 711.02.
518.09 Excavation. Excavate all material encountered to the dimensions necessary to provide
ample space at least to install pipe or other drainage facility behind abutments and for outlets.
518.10 Method of Measurement. The Department will measure Porous Backfill and Porous
Backfill with Geotextile Fabric, by the number of Square Yards (Square Meters), Cubic Yards (Cubic Meters) or lump sum. The Department will measure Prefabricated Geocomposite Drain by the number of Square Yards (Square Meters) or lump sum. The Department will measure pipe specials by the same method as the pipe. If pipe is by the foot (meter), the Department will measure the pipe along its centerline. The Department will measure all Square Yard (Square Meters) items as the area of the abutment or wall being covered for drainage
518.11 Basis of Payment. The cost to backfill, if not separately itemized in the Contract, and
excavation is incidental to the drainage facility that necessitates them. The Department will include bagged aggregate with porous backfill for payment. The Department considers all items to place the Prefabricated Geocomposite Drain including surface preparation, tape, fasteners, adhesives, outlet fittings or other support material, incidental to the Prefabricated Geocomposite Drain. The Department will pay for perforated and non-perforated pipes for the Prefabricated Geocomposite Drain as separate pay items per 518.07. The Department will pay for accepted quantities at the contract prices as follows: Item Unit Description 518 Cubic Yard Porous Backfill (Cubic Meter) or Lump Sum 518 Cubic Yard Porous Backfill with Geotextile Fabric (Cubic Meter) or Lump Sum 518 Square Yard Prefabricated Geocomposite Drain (Square Meter) or Lump Sum 518 Foot (Meter) ___ inch (___ mm) ___ Pipe, Including Specials 518 Each Scuppers, Including Supports 518 Pound or Foot Trough Horizontal Conductors (Kilogram or Meter) 518 Pound or Foot Pipe Horizontal Conductors (Kilogram or Meter) 518 Foot (Meter) ___ inch (___ mm) Pipe Downspout Including Specials
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Source: Construction and Material Specifications, 2023 (rev. 7/17/2026) Edition. Pages 418–422 of 892. View official source ↗