4.
Precast reinforced concrete sections shall be set vertical and with sections in true
alignment.
Butyl rubber joint sealant shall be installed between each concrete section. Catch basin
sections do not require joint sealant if so indicated on the drawings.
All holes in sections used for handling the sections shall be thoroughly plugged with mortar.
Mortar shall be one part cement to 1-1/2 parts sand, mixed slightly damp to the touch (just
short of "balling"), hammered into the holes until it is dense and an excess of paste appears
on the surface, and then finished smooth and flush with the adjoining surfaces.
B. BRICK WORK:
1.
Bricks shall be moistened by suitable means, as directed, until they are neither so dry as to
absorb water from the mortar nor so wet as to be slippery when laid.
Each brick shall be laid as a header in a full bed and joint of mortar without requiring
subsequent grouting, flushing or filling, and shall be thoroughly bonded as directed.
The brick inverts shall conform accurately to the size of the adjoining pipes. Side inverts
shall be curved and main inverts (where direction changes) shall be laid out in smooth curves
of the longest possible radius which is tangent to the centerlines of adjoining pipe.
C. CASTINGS:
1.
Cast iron frames, grates and covers shall be as specified. The frames and covers shall be
set by the Contractor to conform accurately to the grade of the finished pavement,
existing ground surface, or as indicated on the drawings. Frames shall be adjusted to meet
the street surface.
Cast iron manhole frames and covers not located in paved areas shall be set 6-inches above
finished grade, at a height as directed by the Engineer, or as indicated on the drawings. The
top of the cone shall be built up with a minimum of | course and a maximum of 5 courses
of brick and mortar used as headers for adjustment to final grade.
Frames shall be set concentric with the top of the concrete section and in a full bed of mortar
so that the space between the top of the concrete section or brick headers and the bottom
flange of the frame shall be completely filled and made watertight. A thick ring of mortar
extending to the outer edge of the concrete shall be placed all around the bottom flange.
The mortar shall be smoothly finished to be flush with the top of the flange and have a slight
slope to shed water away from the frame.
Covers and/or grates shall be left in place in the frames, for safety reasons, except while
work is being performed.
2022 Sewer Replacement Project Precast Manholes and Catch Basins
Nashua, NH
02631-6
