[HISTORY: Adopted by the Board of Health
of the Town of Dalton 8-21-1989. Amendments noted where applicable.]
A.
Provided that the groundwater level is a minimum of
two feet above the top of the pipe, leakage tests by infiltration
shall be performed after the backfill has been placed. The Engineer
shall determine if this condition exists. Infiltration tests shall
be made when directed by the Engineer, and the length of line to be
tested shall be not less than the length between adjacent manholes
and not more than the total length of each size of pipe. The allowable
infiltration shall be 100 gallons per inch of diameter per day per
mile of pipe. Leakage between two adjacent manholes may be up to twice
the amount above stated, provided that the average leakage for the
total length of any size does not exceed the amount first stated and
provided that there are no gushing or spurting leaks.
B.
If an inspection of the completed sewer or any part
thereof shows pipes or joints which allow noticeable infiltration
of water, the defective work or material shall be replaced or repaired
as directed.
C.
Rates of infiltration shall be determined by means
of V-notch weirs, pipe spigots, or by plugs in the end of the pipe
to be provided and installed by the contractor in an approved manner
and at such times and locations as may be directed by the Engineer.
D.
If the groundwater table is not at a sufficient elevation
to make the infiltration test acceptable, an exfiltration test must
be performed. Water shall be used.
A.
Leakage tests by exfiltration will be made on all
pipe before or after backfilling at the discretion of the Engineer.
The contractor will be required to test the first section of pipeline
installed to demonstrate that the work conforms to these specifications.
The initial test section shall be not less than the length of pipe
between adjacent manholes and not more than 1,000 feet of pipeline.
Testing of all pipe shall closely follow pipe laying. The length of
the pipe to be tested shall be such that the head over the downstream
crown is not more than six feet. The pipe shall be plugged by pneumatic
bags or mechanical plugs in such a manner that the air can be released
from the pipe while it is being filled with water. The test shall
be continued for one hour, and provisions shall be made for measuring
the amount of water required to maintain the water at a constant level
during this period.
B.
If any joint shows an appreciable amount of leakage,
the jointing material shall be removed and the joint remade or replaced.
If any pipe is defective, it shall be removed and replaced. If the
quantity of water required to maintain a constant level in the pipe
for one hour does not exceed 100 gallons per inch of diameter per
day per mile of pipe and all the leakage is not confined to a few
joints, the workmanship shall be considered satisfactory. If the amount
of leakage indicates defective joints or broken pipe, they shall be
corrected, and the line shall be retested.
A.
In lieu of the water exfiltration test described above,
and where applicable as determined by the Engineer, the contractor
shall perform an air pressure test on the pipe. The pressure test
section shall not be more than the length of pipe between adjacent
manholes.
B.
The contractor shall plug the pipe opening in the
downstream manhole and place the pressure testing apparatus in the
upstream manhole at the opening of the pipe section to be tested.
C.
A pressure of 3.5 psi shall be reached in the test
section. The valve on the pressure testing apparatus shall then be
closed.
D.
The minimum time duration permitted for a low-pressure
exfiltration test between two consecutive manholes shall not be less
than that shown in the table below. The prescribed pressure drop shall
not exceed 0.5 psi for 3.5 to 3.0 psi in excess of the groundwater
pressure above the top of the sewer. If the pipe section fails the
test, the contractor shall locate the defects and repair or replace
the defects at his expense. The pipe section shall then be retested
until the allowable pressure drop is met.
|
Pipe Size
(inches)
|
Time
(minutes)
| |
|---|---|---|
|
4
|
2.5
| |
|
6
|
4
| |
|
8
|
5
| |
|
10
|
6.5
| |
|
12
|
7.5
| |
|
15
|
9.5
|
A.
Pipe deflection measured not less than 90 days after
the backfill has been completed as specified shall not exceed 7.5%.
The allowable minimum diameter shall be computed by multiplying the
base inside diameter as listed in ASTM D3034 by 0.925.
B.
Deflection shall be measured with a rigid mandrel
(Go/NO/Go) device cylindrical in shape and constructed with a minimum
of nine or ten evenly spaced arms or prongs. Drawings of the mandrel
with complete dimensions shall be submitted to the Engineer for each
diameter of pipe to be tested. The mandrel shall be hand pulled by
the contractor through all sewer lines.
C.
Any section of sewer not passing the mandrel shall
be uncovered and the contractor shall replace the sewer at the contractor's
expense.
At the conclusion of the work, the contractor
shall thoroughly clean all of the new sewers by flushing with water
or other means to remove all dirt, stones, pieces of wood, or other
material which may have entered during the construction period. Debris
cleaned from the lines shall be removed from the lowest manhole. If,
after this cleaning any obstructions remain, they shall be removed.
Leakage tests shall be made by the contractor
on each manhole and shall be observed by the Engineer. The test shall
be the exfiltration test made as described below:
A.
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 watertight. 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. At the end of this period, the manhole shall be refilled
to the top of the cone, if necessary, and the measuring time of at
least eight 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 twenty-four-hour
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 twenty-four-hour period.
B.
If the manhole fails this requirement, but the leakage
does not exceed three 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 three-gallon
per vertical foot per day shall be cause for the rejection of the
manhole. It shall be the contractor's responsibility to uncover the
manhole as necessary and to disassemble, reconstruct or replace it
as directed by the Engineer. The manhole shall then be retested as
specified and to the satisfaction of the Engineer.
C.
No adjustment in the leakage allowance will be made
for unknown causes such as leaking plugs, absorptions, etc., i.e.,
it will be assumed that all loss of water during the test is a result
of leaks through the joints or through the concrete. Furthermore,
the contractor shall take any steps necessary to assure the Engineer
that the water table is below the bottom of the manhole throughout
the test.
D.
In lieu of the water leakage test mentioned above,
and where applicable as determined by the Engineer, the contractor
shall perform a vacuum test on the manholes.
E.
The vacuum test shall be done immediately after the
complete assembly of the manhole (including filling liftholes, etc.,
as specified).
F.
The contractor shall plug the pipe openings and place
the vacuum testing apparatus in the manhole using a sixty-inch per
pound torque to tighten the external clamps. The compression band
shall then be inflated to seal the vacuum base. The vacuum pump shall
be connected to the outlet port of the base with the valve open. A
vacuum of 10 inches of Hg shall be drawn. The valve shall then be
closed.
G.
The test shall pass if the vacuum remains at 10 inches
Hg or drops to nine inches Hg in a time greater than one minute. If
the manhole fails the initial test, the contractor shall locate the
leak and make the proper repairs. Leaks may be filled with a wet slurry
of quick-setting material as approved by the Engineer.
All new manholes shall be thoroughly cleaned
of all silt, debris and foreign matter of any kind, prior to final
inspection.
