289 ALASKA 2020 SECTION 604
604-1.01 DESCRIPTION . Construct, reconstruct, relocate, or adjust manholes and inlets.
604-2.01 MATERIALS. Use materials that conform to the following:
Concrete Section 550, Class B Clay or Shale Brick Subsection 70 4-2.01 Concrete Brick Subsection 704- 2.02 Concrete Masonry Block Subsection 704- 2.03 Joint Mortar Subsection 705- 2.04 Flexible Watertight Gaskets Subsection 705- 2.05 Reinforcing Steel Subsection 709- 2.01 Precast Concrete Manhole Sections Subsection 712- 2.05 Frames, Grates, and Covers, Subsection 712- 2.06 Corrugated Metal Units Subsection 712- 2.07
604-3.01 CONSTRUCTIO N REQUIREMENTS. Install precast concrete manholes consisting of a
base, risers, cone or flat top; with steps, pipe boots, frame and cover as s hown on the Plans. Use flexible watertight gaskets between concrete sections. Tighten watertight boots over all pipes, then grout pipes in place. Install inlets consisting of a precast concrete catch basin box, risers, metal frame and grate as shown on th e Plans. Grout pipes into place. Construct cast -in-place concrete manhol es and inlets to conform to the requirements of Section 550 and the details shown on the Plans. Use full mortar joints no more than 1/2 inch wide. Set metal frames in full mortar bed. When specified, plaster the outside face of concrete structures with a 1/2 inch thick cement -sand mortar coat. Cure exposed surfaces of concrete and masonry with wet burlap for at least 48 hours. Fit each pipe section flush on the inside of the struc ture wall and to project far enough outside to connect properly with the next pipe section. Fit masonry neatly and tightly around the pipe. Construct invert channels in all manholes used for sanitary or combined sanitary and storm sewers. Construct channels to be smooth and semicircular to conform to the inside of the adjacent sewer sections. Make changes in flow direction along a smooth curve with as large a radius as the manhole size permits. Make gradual and even changes in channel size and grade. Form invert channels by using any of the following methods:
1.Directly in manhole concrete base
2.Built up with brick and mortar
3.Laying half tile in concrete
4.Breaking out the top one- half of full sections of pipe, laid through the manhole, after the surrounding concrete has hardened 290 ALASKA 2020 Construct smooth floor outside the invert channel so that it slopes towards the channel not less than 1 inch or more than 2 inches per foot. Adjust existing manhole, manhole top section, or inlet by raising or lowering the frame or ri ng casting 12 inches or less, without reconstructing the cone section. Reconstruct or replace components of existing manhole or manhole top section by using one or more of the following methods:
1.Bring the manhole frame and cover to grade if you remove the cone for lowering.
2.Raise the manhole frame and cover more than 12 inches.
3.Reconstruct a portion of the manhole with no change in line or grade.
4.Tap one or more additional pipes into an existing manhole.
5.Rotate the manhole cone to align the lid to the sho ulder, lane line, or middle of driving lane.
6.Rotate the manhole cone to align the inlet casting to the curb line.
7.Align the access stairs by rotating the barrel sections or install new steps. Reconstruct the manhole or manhole top section to the required e levation so that it conforms to plan details. Complete this work according to the requirements for new construction. Reuse material only if the Engineer approves. Align manholes designed to fall within the paved roadway surface so that the casting is not in the driving lane wheel path or in the gutter pan flow line. In roadways, set the manhole frame and cover flush with or no more than 3/8 inch below the finished pavement surface. In walkways and bike paths, set the manhole frame flush with the surface. Do not impede existing sewer flow during construction. Relocate inlet by removing and reinstalling inlet box, frame, and grate at new location. Relocate manhole by removing and reinstalling manhole barrel, cone, frame, and cover at new location.
604-4.01 METHOD OF MEASUREMEN T. The number of units installed and accepted.
604-5.01 BASIS OF PA YMENT. Excavation and backfill are paid for under Section 204.
Payment will be made under: PAY ITEM Item Number Item Description Unit 604.0001.____ Storm Sewer Man hole EACH 604.0002.____ Sanitary Sewer Manhole EACH 604.0003.____ Reconstruct Existing Manhole EACH 604.0004.____ Adjust Existing Manhole EACH 604.0005.____ Inlet, Type ___ EACH 604.0006.____ Relocate Inlet EACH 604.0007.____ Relocate Manhole EACH 604.0008.____ Reconstruct Manhole CS 291 ALASKA 2020 PAY ITEM Item Number Item Description Unit 604.0009.____ Reconstruct Manhole Top Section EACH 604.0010.____ Reconstruct Inlet EACH 604.0011.____ Replace Manhole Top Section EACH 604.0012.____ Replace Inlet Frame and Grate EACH 604.0013.____ Replace Inlet Gra te EACH 604.0014.____ Remove and Replace Sewer Manhole Frame and Lid EACH 604.0015.____ Remove and Replace Storm Drain Manhole Frame and Lid EACH 604.0016.____ Adjust Inlet Frame and Grate EACH 292 ALASKA 2020 SECTION 605 UNDERDRAINS
605-1.01 DESCRIPTION . Construct underdrains and blind drains, underdrain outlets, cleanouts,
and marker posts.
605-2.01 MATERIALS. Use materials that conform to the following:
Porous Backfill Material Subsection 703- 2.10 Perforated Concrete Pipe Subsection 706- 2.03 Perforated PVC Pipe Subsection 706- 2.06 Perforated Corrugated Polyethylene Pipe Subsection 706- 2.07 Corrugated Steel Pipe Subsection 707- 2.01 Bituminous Coated Corrugated Steel Pipe Subsection 707- 2.02 Corrugated Aluminum Pipe Subsection 707- 2.03 Gray Iron Casting Subsection 719-2.02 Marker Post Subsection 730- 2.05 CONSTRUCTION REQUIREMENTS
605-3.01 PIPE INSTAL LATION. Excavate trenches to the dimensions and grade required by the
Plans or as directed. Place and compact a 3- inch minimum bedding layer of porous backfill material in the bottom of the trench for its full width and length. Use coupling bands for 6 inch, 8 inch, and 10 inch diameter corrugated underdrain that are 2 piece, 7 inch minimum width and corrugated to match the corrugations of the pipe. Place perforated pipe with the perforations down. Join pipe end sections securely with the appropriate coupling fittings or bands. Plug or cap up- grade ends of subdrain pipe to prevent entry of soil materials. After the pipe installation has been inspected and approved, plac e porous backfill material to a height of 12 inches above the top of pipe. Place and compact the remainder of the porous backfill material as specified in Section 204, to the required height. Fill trench above the porous backfill with specified material.
605-3.02 UNDERDRAIN OUTLETS. Excavate trenches for underdrain outlets to the width and
depth shown on the Plans. Lay pipe in the trench with ends firmly joined. Backfill the trench after inspection and approval of the pipe installation.
605-3.03 BLIND DRA INS. Excavate trenches for blind drains to the width and depth shown on
the Plans. Fill the trench with specified backfill materials to the depths required by the Plans. Compact all backfill material.
605-4.01 METHOD OF M EASUREMENT. See Section 109 and as follows:
Underdrains, including outlets, and blind drains are measured along the invert. Porous backfill material is measured by calculated volume, using Plan dimensions for trench width, depth, and measured invert length of perforated pipe.
605-5.01 BAS IS OF PAYMENT. When not listed in the bid schedule, porous backfill material is
subsidiary. Pipe cleanouts, including the cast iron cover and marker post are subsidiary. Excavation is paid for under Section 204.
Source: Alaska Standard Specifications for Highway Construction, 2020 Edition. Pages 317–319 of 584.