662Manholes

662.1 Description

This Work consists of construc ting manholes. The Contractor s hall construct manholes complete with covers, steps, fittings, and other appurtenances. This Work also includes installation of reducing cones, m anhole extensions, ties to exi sting manholes, manhole adjustments, and manhole frame and covers.

662.1.1 NMSSPWC Appurtenant Stipulations

The Contractor shall adhere to the applicable requirements of the NMSSPWC, except for the procedures for Method of Measurement and Basis of Payment. 662.1.1.1 Terms The Contractor shall substitute “Engineer,” as it appears in t he applicable sections of the NMSSPWC, with “Project Manager.” The term “Owner” refers to the entity owning the affected utilities on this Project.

662.1.2 Manhole Types

The Contractor shall use precas t concrete sections to construc t “Drop” and “Standard” manholes. The Department defines “Drop” m anholes as manholes that have o utside pipe and fittings for dropping sewage into the lower line. The Department defines “Standard” manholes as inside drop manh oles, where the incoming line discharges direc tly into the manhole and does not require special fittings.

662.2 Materials

622.2.1 General

The Contractor shall use new Materials of the best standard qu ality available for the intended purpose. The Contractor may substitute Contract specified brand name Ma terials with generic Materials of equal quality if the Contractor provides adequate technical and descriptive data and the Project Manager approves.

662.2.1 1 Referenced Materials

The Contractor shall provide Materials in accordance with thes e Standard Specifications and the following sections of the NMSSPWC: 1. Section 106, “Cement Mortar and Grout";” 2. Section 108, “Brick;” 3. Section 123, “Reinforced Concrete Pipe;” 4. Section 124, “Reinforced Concrete Pressure Pipe;” 5. Section 128, “Concrete Cylinder Pipe;” 6. Section 130, “Gray Iron and Ductile Iron Fittings;” 8. Section 160, “Steel Castings;” 9. Section 161, “Gray Iron Castings;” and 10. Section 162, “Alum inum Castings.” If the above-referenced S pecifications and these Standard Specifications conflict, the Contractor shall use the more stringent.

662.2.1 2 Certification

Before installing an item or type of Material, the Contractor shall provide the Project Manager with a certification that the item or type of Material meets these Standard Specifications or the referenced Specifications.

662.2.2 Masonry

662.2.2 1 Concrete

The Contractor shall provide Materials for concrete in accorda nce with Section 509, “Portland Cement Concre te Mix Designs.”

662.2.2 2 Non-Shrink Mortar

The Contractor shall provide non-shrink mortar in accordance w ith Section 521, “Non- Shrink Mortar.”

662.2.3 Fine Aggregate

The Contractor shall provide fine aggregate that passes a No. 8 sieve, but no more than four percent (4%) passes the No. 200 sieve.

662.2.4 Precast Sections

The Contractor shall provide circular precast concrete in acco rdance with ASTM C 478, except that the minimum thickness and the reinforcement will be in accordance with the Contract. The Contractor shall provide circular or horseshoe-shaped box out openings for each connecting pipe, with the surfac es grooved or roughened to impr ove mortar bond.

662.2.5 Gaskets

The Contractor shall provide rubber or mastic gasket Materials in accordance with the following: 1. Mastic in accordance with Federal Specification SS-S-210; an d 2. Rubber that is Neoprene, or another synthetic, and 40 ± five (5) hardness if, measured in accordance with ASTM D 2240 and Type A durometer.

662.2.6 Coal Tar Paint

The Contractor shall provide one (1) of the following types of coal tar paint: 1. Koppers Bitumastic Super-Service Black; 3. Tnemec 450 heavy Tenemecol, or; 4. An approved equal.

662.2.7 Castings

The Contractor shall provide castings in accordance with ASTM A 48, with asphalt varnish coating applied at the foundry. The Contractor shall provide the following manhole rings and c overs: 1. Neenah R-1736; 2. Clay and Bailey No. 2008; 3. McKinley ET 24 M; or 4. An approved equal. The Contractor shall provide aluminum manhole steps or polypro pylene-encased deformed-steel reinforcing bar manhole steps in accordance with ASTM C 478.

662.3 Construction Requirements

662.3.1 General

The Contractor shall make excavations, as necessary, to determ ine the exact location of existing utilities that affe ct the new construction. The Contractor shall repair damage to existing utilities at no additional cost to the Department. The Project Manager will establis h the final locations for new fittings, connections, etc. in the field. The Project Manager m ust approve modifications to t he Contract before beginning the Work. The Contractor shall submit a proposed sequence of constructio n to the Project Manager for approval before beginning the Work.

662.3.1 1 Waste Containment and Disposal Requirements

The Contractor shall dispose of Materials taken from sanitary sewers during cleaning operations at no additional c ost to the Department. The Contractor shall retrieve and dispose of sand and other de bris from the sewers and secure a legal disposal site a t no additional cost to the Depar tment. The Contractor shall not discharge removed sewage or solids on to Streets, ditches, catch basins, or storm drains.

662.3.2 Delivery

The Contractor shall not deliver precast concrete sections to the Project until representative concrete control cylinders have attained at leas t 80% of the specified minimum compressive strength. The Contractor shall inspect precast con crete sections upon delivery and the Contractor shall not use cracked, broken, or visibly de fective units. The Contractor shall use mortar within 40 min after mixing. T he Contractor shall discard mortar that has begun to take on initial set and the Contractor shall not mix it with additional cement or new mortar. If necessary, the Contractor shall exten d the manhole as directed by the Project Manager.

662.3.3 1 Inverts

The Contractor shall ensure that the dimension of the invert s ection through a manhole is greater than that of the outgoing pipe. The Contractor shall e nsure that the shape of the invert conforms exactly to the lower half of the pipe it connects. Th e Contractor shall connect side branches with as large a radius o f curve as practical. The Con tractor shall trowel inverts to a smooth, clean surface.

662.3.3 2 Precast Sections

The Contractor shall provide circular precast sections with a rubber or mastic gasket to seal joints between sections. The Contractor shall fill the sp ace between connecting pipes and the wall of precast sections c ompletely with non-shrinking mortar.

662.3.4 Connections

The Contractor shall make connections in a sequence and method that minimizes inconvenience to the Owner. The Contractor shall obtain Projec t Manager approval of the sequence and method before making the connections. To stop the flow of water to make the connection to the existi ng line, the Contractor shall only close existing valves in t he presence of an Owner represen tative.

662.3.5 Manhole Frames and Covers

The Contractor shall cast or finish manhole frames and covers in accordance with the Plans. The Contractor shall use machined cover seats and frame seats made of tough gray iron, free of cold chutes or blow hol es, and with a finish to industr y standards. The Contractor shall produce an indentation on a rectangular edge using a hammer wit hout flaking the metal. The Contractor shall perform the following to castings at the foundry: 1. Hammer inspection; 2. Thoroughly clean; 3. Dip in asphalt or coal tar; and 4. Oil at a temperature of from 290 °F to 310 °F. The Contractor shall use manhole frames and covers in accordan ce with the Contract. The Contractor shall cast, finish, and machine the frame and co ver so that the cover sits true and even, without rocking within the frame. The Contractor shall ensure the position and spacing of the ma nhole step rungs are in accordance with the Contract.

662.3.6 Submittals

Two (2) weeks before installation, the Contractor shall submit drawings and data regarding precast concrete secti ons to the Department. The Con tractor shall submit data and drawings regarding cast-in-plac e manholes to the Department in accordance with Section 510, “Portland Cement Concrete,” and Section 511, “Concrete Structur es.”

662.3.7 Manhole Adjustments

The Contractor shall adjust m anhole rings in existing paved Ro adway using the following procedure: 1. Remove the existing ring and cover; 2. Place a 5/8 inch thick (minimum) steel plate cover on the ma nhole opening; 3. Salvage the existing manhole rings and manhole covers and re turn them to the Owner as directed; 4. Place and compact the required surfacing; 5. Locate the steel-plate manhole cover with a metal detector o r other method approved by the Project Manager; 6. Cut a five (5) foot × five (5) foot square opening in the su rfacing and remove the surrounding Material in accordance with the Plans (the control point of the square opening is the center of the manhole); 7. Install a manhole ring and adjus t in accordance with the Pla ns; 8. Place the steel reinforcement and concrete (the Project Mana ger will determine the curing time allowed for the plac ed concrete before other Work a djacent to or over the concrete can be started); and 9. Place and compact the required surfacing. The Contractor may propose an alternate method of adjusting ma nholes by providing the Project Manager the proposed procedure in writing. The Contrac tor shall not use the proposed procedure until Project Manager approval.

662.3.8 Miscellaneous Manhole Construction

If specified, the Contractor shall install reducing cones, man hole extensions, ties to existing manholes, manhole adjus tments, and manhole frame and c overs in accordance with the NMSSPWC.

662.4 Method of Measurement

The Department will measure additional depth for adjusted manh oles from the inside bottom of the manhole to the adjusted finished top of the manho le ring and compare that measurement to the Plan depth.

662.5 Basis of Payment

Pay Item Pay Unit Manhole Type __, __ft diameter ___ft to ___ft Depth Each Manhole Type __, __ft diameter over ___ft to ____ft Depth Each Manhole Type ___ Each Special Manhole Type ___ Each Manhole, ___ft diameter Each Section 662: Manholes Page 739 Sewer Manhole, ___inch diameter Each Drop Manhole, ___inch diameter Each ___ inch × ___inch Reducing Cone Each Manhole Adjustment Each Manhole Extension Each Tie to Existing Manhole Each Manhole Frame and Cover E a c h Section 663: Utility Items Page 740