2. The manhole shall be filled with water to the top of the cone section. If the excavation
has not been backfilled and observation indicates no visible leakage, that is, no water visibly
moving down the surface of the manhole, the manhole may be considered to be
satisfactorily water-tight. If the test, as described above, 1s unsatisfactory as determined
by the Engineer or 1f the manhole excavation has been backfilled, the test shall be
continued. A period of time may be permitted if the Contractor so wishes, to allow for
absorption by the manhole. At the end of this period, the manhole shall be refilled to
the top of the cone, if necessary, and a measuring time of at least 8 hours begun. At the
end of the test period, the manhole shall be refilled to the top of the cone, measuring the
volume of water added. This amount shall be extrapolated to a 24-hour loss rate and the
leakage determined on the basis of depth. The leakage for each manhole shall not
exceed one gallon per vertical foot for a 24-hour period. If the manhole fails this
requirement, but the leakage does not exceed 3 gallons per vertical foot per day, repairs
by approved methods may be made as directed by the Engineer to bring the leakage
within the allowable rate of one gallon per foot per day. Leakage due to a defective section
or joint or exceeding the 3 gallon per vertical foot per day, shall be cause for rejection of the
manhole. It shall be the Contractor's responsibility to uncover the reyected manhole as
necessary and to disassemble, reconstruct or replace it as directed by the Engineer. The
manhole shall then be retested and, if satisfactory, interior joints shall be filled and pointed.
3. | No adjustment in the leakage allowance will be made for unknown causes such as leaking
plugs, absorption, etc. It shall be assumed that all loss of water during the test is a result
of leaks through joints or through the concrete. Furthermore, the Contractor shall take
any steps necessary to assure the Engineer that the water table 1s below the bottom of the
manhole throughout the test.
4. If the groundwater table is above the highest joint in the manhole, and there is no leakage
into the manhole, as determined by the Engineer, such a test can serve to evaluate water-
tightness of the manhole. However, if the Engineer is not satisfied with the results, the
Contractor shall lower the water table and carry out the test as described hereinbefore.
3.03 CLEANING:
All new manholes shall be thoroughly cleaned of all silt, debris and foreign matter of any kind,
prior to final inspection.
END OF SECTION
2019 Sewer Replacement Project Precast Manholes and Catch Basins
Nashua, NH 02631-8
