SECTION 604 - MANHOLES, INLETS AND CATCH BASINS
604.01 Description. This work consists of the construction of manholes, inlets, and catch
basins in accordance with these specifications and in reasonably close conformity with the details, lines, grades, and dimensions shown on the plans or established by the Engineer. Precast sectional manholes shall consist of furnishing and assembling precast sections for manholes, together with necessary fittings, ba ses, and connections, all constructed in accordance with these specifications and in reas onably close conformity with the details, lines, grades and dimensions shown on the plans, or established.
604.02 Materials. The materials used in this construction shall meet the requirements
specified in the following Section or Subsections: Masonry Brick, Grade SM ............................................................................... 706.01 Mortar ............................................................................................................... 714.11 Concrete ................................................................................................................ 601 Reinforcing Steel ............................................................................ 711.00 and 711.01 Gray Iron Castings ........................................................................................... 716.04 Bar Gratings ..................................................................................................... 716.14 All bars, anchors, frames, hangers, etc. for castings and plates shall be approved prior to installation. Inlet and outlet pipes shall be of the type, cl ass and size indicated on the plans and shall conform to the requirements as set out in Section 603 for the particular type, class, and size of pipe specified. Precast units will be considered for use unde r the provisions of Su bsection 601.02.3. Precast (sectional) manholes shall conform to the requirements of AASHTO M 199.
604.03 Construction Requirements.
604.03.1 Brick Masonry. Brick masonry shall be constructed in conformity with the
details shown on the plans and in accordance with the provisions of Section 611. Where irons or other fittings enter the brick work, they shall be placed as the work is laid up, thoroughly bonded, accurately spaced, and lined. Upon completion of the masonry and setting of castings and fittings, the inside a nd outside surfaces of the masonry shall be neatly plastered with mortar 1/2 inch thick. Plastering shall have a uniform, smooth finish and shall be neatly pointed to all fittings.
604.03.2 Concrete Masonry . Unless otherwise specified, concrete masonry shall be
constructed of Class "B" concrete in accordance with the requirements of Section 601.
604.03.3 Reinforcement. Reinforcement shall be placed as indicated on the plans or as
directed and in accordance with the provisions of Section 602.
604.03.4 Optional Construction. When plan standards indicate portions of the structure
may be constructed of either brick masonry or concrete, the Contractor may use either concrete or brick masonry for these portions, provided the plan dimensions for wall thickness, etc. are maintained. In either case the masonry, whether concrete or brick, will be measured for payment as stipulated in Subsection 604.04.
604.03.5 Inlet and Outlet Pipes. Unless otherwise directed, inlet and outlet pipes shall
extend through the walls of manholes and catch basins for a sufficient distance beyond the outside surface to allow for connections and shall be cut flush with the wall on the inside surface and neatly pointed. The concrete, or brick and mortar, shall be constructed around the pipes so as to prevent leakage and to form a neat connection.
604.03.6 Castings, Gratings, and Fittings. All castings and gratings shall be carefully
handled. Injurious cracks, chips, surface mars, etc. that render them unsuitable for use or unsightly after being placed will be cause for rejection. The castings, gratings, and fittings shall be placed as indicated on the pl ans or as directed to line and grade and in such a manner that subsequent adjustments will not be necessary. When castings or gratings are to be set in co ncrete or cement mortar, all anchors or bolts shall be in the correct place and position before the concrete or mortar is placed, and they shall not be disturbed while the concrete or mortar is hardening. Castings and gratings placed on previously constructed masonry shall be set in mortar beds or anchored to the masonry as shown on the plans or directed. The bearing surface of the original masonry shall present an even surfa ce and conform to line and grade so that the entire face or back of the casting will come in contact with the masonry. Castings and gratings shall be set firm and snug so that they will not rattle, shake, or move unnecessarily.
604.03.7 Precast Manholes. As trenches are opened for the pipe conduit, truly leveled
bases shall be prepared at each manhole site. The bases may be cast-in-place or may consist of precast base units. In either case, the seated base shall be truly horizontal. Inverts shall be smooth and accurately shaped to a semi-circular bottom conforming to the inside of the adjacent conduit, and extend upward at least half of the diameter of the conduit, or as shown on the plans. Joints shall be sealed in accordance with Section 603. Steps in the manhole may be of cast-iron, aluminum, wrought iron, plastic or other material approved by the Engineer. All steps shall be built into the walls of precast sections in straight alignment to form a continuous ladder with a maximum distance of 16 inches between steps. Each precast section shall have not more than two holes for handling. The holes shall be plugged with mortar after installation. Concrete covers may be precast, or cast at the site. The covers shall be cast accurately to the dimensions and design indicated on the plans.
604.03.8 Excavation and Backfill. Excavation shall be performed as required for proper
construction. Backfill shall be performed in accordance with the provisions of Subsection
203.03.8 6.
604.03.9 Cleaning Up. Upon completion, all structures shall be thoroughly cleaned of
accumulations of silt, debris, and foreign matter. All surplus material shall be removed, and the site and the structure shall be maintained in a clean and neat condition until release of maintenance.
604.04 Method of Measurement . When either concrete masonry or brick masonry is
permitted, and when concrete is specified, measurement will be by the cubic yard in accordance with Subsection 601.04 for Structural Concrete - Minor Structures. Precast manholes will be measured per linear foot of depth from the flowline of the manhole to the top of the cover, or as indicated on the plans. Reinforcing steel will be measured per pound in accordance with Subsection 602.04. When brick masonry only is specified, measurement will be by the cubic yard or per thousand (M) brick in accordance with Subsection 611.04.
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