Times (Seconds)
0-12 30 39 49
12-16 40 52 67
16-20 50 65 81
20-24 59 78 97
26-30 74 98 121
If the manhole fails the initial test, the Contractor shall locate the leaks and make
proper repairs. Leaks may be filled with a wet slurry of accepted quick setting
material. If the manhole should again fail the vacuum test, additional repairs shall be
made, and the manhole water tested as specified below.
C. WATER EXFILTRATION TEST:
lL.
After the manhole has been assembled in place, all lifting holes shall be filled and
pointed with an approved non-shrinking mortar. All pipes and other openings into the
manhole shall be suitably plugged and the plugs braced to prevent blow out. The test
shall be made prior to placing the shelf and invert. If the groundwater table has been
allowed to rise above the bottom of the manhole, it shall be lowered for the duration
of the test.
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, is
unsatisfactory as determined by the Engineer or if 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 rejected
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.
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
2019 CIPP Lining Project
Nashua, NH
Pr
