C. CASTINGS:
L.
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 1 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.
D. ACCESSORIES:
l.
2.
Accessories shall be installed in accordance with manufacturer's instructions.
Stubs shall be set accurately to the dimensions indicated on the drawings. Stubs
shall be sealed with suitable watertight plugs.
3.02 LEAKAGE TESTS:
A. Leakage tests shall be made by the Contractor and observed by the Engineer on each
manhole. The test shall be by vacuum or by water exfiltration as described below:
B. VACUUM TEST:
1.
The vacuum test shall be conducted in accordance with ASTM C1244. Test results
will be judged by the length of time it takes for the applied vacuum to drop from 10
inches of mercury to 9 inches. If the time is less than that listed in Table 1 of ASTM
C1244, the manhole will have failed the test. Test times from Table 1 are excerpted
below.
TABLE | Minimum Test Times for Various Manhole Diameters
Diameter (Inches)
Depth (Feet) 48 60 72
2019 CIPP Lining Project Precast Manholes
Nashua, NH
02631-6
