(A) General. All precast structures to be used in the project shall be structurally sound and free of defects. Any spalled concrete or voids shall be properly patched or repaired using equivalent strength grout and properly cured before placement. Structures showing excessive cracking or damage should be rejected and replaced at the discretion of the town.
(B) Concrete strength. All concrete used in the manufacturing of precast structures shall have a minimum compressive strength of 4,500 psi at 28 days and meet all applicable requirements of Class “A” concrete.
(C) Sewer manholes.
(1) All manholes for sanitary or storm sewers shall be made water-tight and of size and dimensions as shown on the plans.
(2) The base, riser sections, eccentric cone and adjustment rings shall conform to ASTM C478. The joints between the base, riser sections and the bottom joint of the eccentric cone shall be tongue and groove type with a continuous rubber ring gasket conforming to ASTM C443 or a preformed flexible plastic gasket type joint sealant such as RUB’R-NEK as manufactured by K.T. Synder Company or equal. In addition to the gasket, the joint shall be sealed with an approved mastic.
(3) The top of the eccentric cone shall be joined to the adjustment rings (if necessary) using a preformed flexible plastic gasket type joint sealant to obtain a water-tight fit.
(4) The manhole frame and cover shall be sealed to the adjustment rings or cone section using a preformed flexible plastic gasket type joint sealant.
(5) A water-tight flexible connection shall be made between the manhole and the sewer pipes using elastomeric gaskets conforming to ASTM C923. Gaskets shall be Kor-N-Seal as manufactured by National Pollution Control Systems, Inc. of Miford, New Hampshire, or equal and be installed in strict conformance with the manufacturer’s instructions.
(D) Lift station structures and valve vaults.
(1) Lift station structures and valve vaults shall be made water-tight of size and dimensions shown on the plans.
(2) Precast structures shall meet all requirements of division (B) above, except that flat top slabs shall be used in place of eccentric cones.
(3) Where required by the plans, access hatch frames as specified herein shall be integrally cast into the top slab.
(4) All concrete surfaces subject to sewer gases shall be protected by application of coal tar epoxy suitable for the intended use. These surfaces include all areas in lift station wet wells above the specified low water level. Epoxy shall be 46H-413 Tneme-Tar as manufactured by Tnemec, or equal. Apply one coat at dry mil thickness of 16 to 20 mils unless otherwise recommended by the manufacturer.
(E) Utility vaults.
(1) Utility vaults for underground electrical conduit runs shall consist of two piece square or rectangular precast sections meeting the requirements of ASTM C857.
(2) The vaults shall be made water-tight by including a continuous rubber gasket conforming to ASTM C443 along the section joint.
(3) Conduit knockouts shall be located as required for the actual installation. Only those knockouts specifically used shall be removed.
(F) Frames and covers.
(1) Frames and covers shall be included for all manholes, utility vaults and where otherwise shown on the plans.
(2) Ferrous castings shall be as manufactured by Neenah Foundry Company, East Jordan Foundry, or equal, and shall conform to ASTM A48 Class 30. The covers and frames shall be of a design, type and weight specified on the plans.
(3) Castings shall be of uniform quality, free from blowholes, porosity, hard spots, shrinkage defects, cracks or other injurious defects. They shall be smooth and well cleaned by shot blasting or other approved methods. They shall be coated with high grade bituminous asphalt paint.
(G) Manhole steps.
(1) Steps shall be supplied for all manholes, valve vaults and utility vaults and where specifically detailed on the plans. Steps shall be cast in the precast sections.
(2) Steps shall be made of copolymer polypropylene plastic and reinforced with Y Grade 60 steel. Steps shall be able to resist a 1,500-pound pullout force.
(3) Steps must comply with all applicable provisions of OSHA regulations.
(4) Manhole steps shall be Model PSI-PF as manufactured by M.A. Industries, Inc. of Peachtree, Georgia or equal.
(H) Access hatch.
(1) (a) Where shown and required by the details, access hatches shall be provided for precast structures. Hatches shall be either single or double door with a frame assembly fabricated of aluminum and capable of withstanding a live load of 300 pounds/square feet. The doors shall be equipped with heavy forged brass hinges, stainless steel pins, spring operators and an automatic hold open bar with release handle which holds the door open at 90 degrees.
(b) Each door shall be provided with a lifting handle.
(2) The access frames shall be sized as shown on the drawings. Where noted, sizing may be contingent upon recommendations by equipment suppliers as required to provide equipment removal.
(3) Access frames shall be accurately placed as an integral part of the precast top slab section.
(4) Access frames shall be protected from direct contact with the concrete by means of a protective coating.
(5) Access frames shall be type “J” or “JD” as manufactured by the Bilco Company, New Haven Connecticut, or equal.
(2004 Code, Art. II, § C, part 2)