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This work shall consist of constructing sanitary sewer manholes at the locations and to the lines, grades, and dimensions shown in the utility plans or special provisions and as directed by the Engineer.
Manholes shall be constructed complete with covers, steps, fittings, and other appurtenances, in accordance with the details shown in the plans or provisions.
This work shall also include installation of reducing cones, manhole extensions, ties to existing manholes, manhole adjustments, and manhole frame and covers when specified in the contract.
All materials shall meet the requirements of Division 10 and the construction requirements in Article 15253 shown below:
Portland cement concrete Section 1000
Curing agents Section 1026
Brick Article 1040-1
Concrete Block Article 1040-2
Mortar Article 1040-8
Precast concrete units Section 1077
Reinforcing steel Section 1070
Structural steel Section 1072
Steps Article 1074-7
Gray iron castings Article 1074-6
Select material Section 1016
Grout used in precast structures shall meet the requirements of Article 10409 except that the mixture shall consist of 1 part portland cement to 2 parts of mortar sand.
The Contractor shall submit to the Engineer catalog cuts and/or shop drawings for precast sections, castings and manholes he proposes to use on the project. These shall be submitted by the Engineer to the State Design Services Engineer for review and approval. Forty days shall be allowed for the review of each submittal.
Materials which have not been approved shall not be delivered to the project. Eight (8) copies of each catalog cut and/or drawing shall be submitted and each shall show the material description, brand name, stock number, size, rating, manufacturing specification and the use for which it is intended.
1525-3 CONSTRUCTION REQUIREMENTS.
Sanitary sewer manholes shall be precast concrete, shall conform to ASTM C478 and shall be as shown on the plans and/or in Roadway Standard Drawings.
Sanitary sewer manholes with brick bases as shown in the Standard Drawings shall be used where directed by the Engineer for manholes of extra depth with more than 2 pipes entering or where an extra large pipe is entering. Such manhole bases shall be constructed of standard size common red brick conforming to ASTM C32 grade MS, and shall be constructed as required in Section 830 of the Standard Specifications with approved mortar. The inside and outside of brick bases shall be plastered with mortar a minimum of 1/2 inch thick.
Joints between precast manhole sections shall be O-ring rubber gaskets conforming to ASTM C443 or butyl rubber gaskets conforming to AASHTO M198.
Connection of pipe to manholes for cored or precast holes shall be by a resilient connector conforming to ASTM C923 and for "horseshoe" type holes shall be by resilient material of rubber or butyl rubber and cement grout.
Manholes, either designated by the plans or having sewer pipes entering with two and one half (2 1/2) feet or more vertical drop shall have an outside drop assembly as shown on the plans and/or as shown on Standard Drawings.
Only manholes which are required to have outside pipe and fittings for dropping sewage into the lower line will be designated as drop manholes.
Inside drop manholes, where the incoming line discharges directly into the manhole and does not require special fittings, shall be considered standard manholes.
Sewer manholes over 3 feet in depth shall have steps, spaced 16 inches on center, of the type shown in the Standard Drawings. Cast iron shall be ASTM A48 Class 30. Steps shall be installed in accordance with the plans or standard details and shall be tested as required in ASTM C478.
Sanitary sewer manholes shall be constructed with invert channels, as shown on the plans or standard drawings, to confine and direct the flow through the manhole. The invert channels shall be smooth finished and shaped to provide an easy transition from inlet to outlet. The benches or shelves shall be finished to a non-slip texture and shall be sloped toward the invert channel. Precast invert channels are recommended but not required.
Manhole frames and covers shall be of cast iron conforming to ASTM A48 Class 30, shall be traffic bearing, and shall have machined contact surfaces and shall have the word "Sewer" cast in. Manhole frames and covers shall be as shown in the Standard Drawings. Covers shall have 2 (two) one inch diameter air vents.
On deep manholes, a transition type manhole may be used provided there is a minimum of 6 feet from the manhole bench to the transition cone and the Engineer approves.
Excavation and backfill shall be done in accordance with Section 1505.
(A) Foundation:
No sanitary sewer manhole shall be placed until the foundation has been approved by the Engineer.
Where the foundation material is found to be of poor supporting value or of rock, the Engineer may make minor adjustment in the location of the structure to provide a more suitable foundation. Where this is not practical, the foundation shall be conditioned by removing the existing foundation material by undercutting to the depth as directed by the Engineer and backfilling with either a suitable local material secured from unclassified excavation or borrow excavation at the nearest accessible location along the project, or foundation conditioning material as classified in Article 10163, consisting of crushed stone or gravel or a combination of sand and crushed stone or gravel approved by the Engineer as being suitable material for the purpose intended. The class of select material to be used for foundation conditioning will be stated on the plans or determined by the Engineer.
Where precast foundation slabs are used, the slab shall be set to within plus or minus 1/2 inch of grade on a bed of compacted bedding material which is from 2 to 3 inches thick.
(B) Cast-In-Place Concrete, Brick, and Block Masonry:
Concrete shall be constructed in accordance with Section 825 and shall be given an ordinary surface finish. Brick masonry shall be constructed in accordance with Section 830. Furnishing and placing reinforcing steel shall be in accordance with Section 425. Block masonry shall be constructed in accordance with Section 834 except that reinforcing will not be required.
All concrete shall be Class B concrete unless otherwise indicated on the plans.
Where necessary to fit field conditions, the dimensions of the manhole and footings shall be varied as directed by the Engineer.
(C) Installation of Precast Units:
The precast sanitary sewer manhole units shall be assembled in accordance with the manufacture's instructions and grouted together to form a sound structural unit. Where it is necessary to use cast-in-place, brick masonry, or block masonry construction as part of the structure, the requirements of Subarticle 15254 (B) shall apply to such construction.
Where necessary to fit field conditions, the dimensions of the manhole and footings shall be varied as directed by the Engineer.
(D) Fittings and Connections:
Where fittings enter the manhole they shall be placed as the work is built up, thoroughly bonded, and accurately spaced and aligned.
Pipe connections shall be made so that the pipe does not project beyond the inside wall of the manhole, and shall be grouted as necessary to make smooth and uniform surfaces on the inside of the manhole. Metal frames for covers shall be set in full mortar beds or secured by methods approved by the Engineer.
(E) Backfill:
After the manhole has been completed, and all forms, falsework, sheetings, and bracing have been removed and the sewer line installed, the excavation shall be backfilled with approved material compacted to the density required by Subarticle 2354(C). Backfilling shall not be done until the concrete or brick masonry has cured for at least 7 curing days, unless otherwise permitted by the Engineer. A curing day shall be as defined in Article 8259 for concrete or Article 8305 for brick or block masonry.
Sanitary sewer manholes will be measured on the "per each" basis and on a "lineal foot" basis for that portion exceeding 6 feet in height.
Measurements will be made for the appropriate diameter of manhole on the actual number constructed as required and accepted. The height of the manhole will be measured to the nearest tenth of a foot from the inside bottom of the manhole to the top of the manhole ring.
Transition manholes will have the measurements broken down to the appropriate diameter. The manhole base section, transition cone, riser cones, grade rings and ring and cover will be classified at the base section diameter and the riser sections classified at their appropriate diameter.
Outside drop assemblies will be measured on a "lineal foot" basis to the nearest tenth of a foot from the invert of the drop inlet pipe to the invert of the top inlet pipe.
Sanitary sewer manholes measured as provided above and accepted will be paid for at the contract unit price per each and at the contract unit price per lineal foot of depth. Such prices and payments will be compensation in full for all materials, labor, equipment, excavation and backfill, and incidentals necessary to complete the work as required.
Outside drop assemblies will be paid for at the contract unit price per lineal foot of depth. Such prices and payments will be compensation in full for all materials, labor, equipment, excavation and backfill, and incidental necessary to complete the work as required.
Payment will be made under:
________Foot Diameter Precast Concrete Sewer Manhole 0-6' Depth Each
Precast Concrete Manhole Wall ______Foot Diameter, Over 6' Height Lineal Foot
Sewer Manhole Outside Drop Assembly Lineal Foot