TM 5-815-5/AFM 88-5, Chap 6/NAVFAC P-418
The contractor shall designate a representative or
tern shall include pulling all of the wellpoints and re-
engineer experienced in dewatering large excavations
lated header pipes, pumps, recirculation tank, and
whose responsibility will be to assure that the dewater-
temporary electrical secondary, as approved by the
ing systems comply with the contract plans and speci-
Contracting Officer. Any holes remaining after pulling
fications with respect to materials, installation, main-
the wellpoints shall be filled with sand. Sump pump-
tenance, and operation of the dewatering systems so as
ing of seepage and surface water thereafter shall con-
to control subsurface pressures, groundwater and seep-
tinue as required to keep the excavation in an unwa-
age, and surface water, and maintain records as speci-
tered condition until all structural concrete work and
fied herein. The "dewatering" engineer's duties shall
backfill are complete, and the succeeding Contractor
include the following:
has assumed responsibility for maintaining the exca-
(1) Materials and equipment. The Contractor's
vation in an unwatered condition.
"dewatering" engineer shall obtain all specified data
h. Method of measurement. Dewatering, as speci-
and supervise making all tests and/or measurements to
fied in f above, to be paid for will be determined by the
determine that all materials incorporated in the work
number of calendar days (24 hours), counted on a day-
are in accordance with the plans and specifications.
to-day basis, the excavation is maintained in an unwa-
Materials and equipment to be checked shall include,
tered condition and pressure relieved, from completion
but not be limited to, well screens, riser pipes, filter
and final acceptance of the concrete mat to the date on
sand, pumps, column pipe, gear drives, couplings, die-
which a written directive to cease pumping operations
sel engines, well discharge pipe and fittings, header
is received from the Contracting Officer.
pipe, valves, discharge system outlet structures, pie-
i. Unit price. Any pressure relief wells and related
zometers, and related appurtenances.
apurtenances required in addition to the specified
(2) Installation. The Contractor's "dewatering"
pressure relief system shall be paid for at the unit
engineer shall check to be sure that specified proce-
price for "additional pressure relief wells."
dures and methods for installing wells, pumps, jet-
eductor wells, piezometers, and any other supplemen-
G-6. Example of type B-2 specifications
tal dewatering or groundwater control system re-
(dewatering and pressure relief).
quired are installed in accordance with the specifica-
a. Scope. This section covers: furnishing, install-
tions and drawings.
ing, operating, and maintaining the dewatering sys-
(3) Operation and maintenance. The Contractor's
tems shown on the drawings and specified herein; un-
"dewatering" engineer shall supervise the operation
watering the Phase I excavation; installing any addi-
and maintenance of the dewatering systems, supple-
tional dewatering wells, pumps, and appurtenances, if
mental groundwater control facilities if any, surface
necessary, to lower and maintain the hydrostatic wa-
water control systems, and shall assist with obtaining
ter level in the sand formation beneath the excavation
all required piezometric, well performance, and flow
to a level at least 5 feet beneath any Phase II excavated
data. The Contractor shall inspect the test starting of
surfaces, and have the capacity to lower the water lev-
each nonoperating dewatering pump and engine in-
el to elevations -29.0 and -35.0 feet beneath the
stalled in a well or on the system on a weekly basis and
chamber and gate bay sections, respectively, of the
include in a daily report reference to the conduct of the
lock for a Red River stage of elevation 60.0 feet; and
test, the number of pumps and engines tested, and any
controlling seepage from the soils above and below the
unsatisfactory performance data and remedial action
bottom of the excavation, not intercepted by the speci-
taken. The Contractor's "dewatering" engineer shall
fied well and jet-eductor systems, by installing addi-
notify the Contractor and the Contracting Officer's
tional jet-eductor wells, wellpoints, pumps, and appur-
Representative (C.O.R.) immediately of any event or
tenances if necessary, so as to assure a stable bottom at
information not in accordance with the specifications.
grade for the Phase II excavation and prevent any sig-
Thirty days prior to completion of the work under this
nificant seepage or raveling of excavated slopes. The
contract, the Contractor shall furnish to the Govern-
dewatering systems shall include deep wells; jet-educ-
ment a complete set of "as-built" drawings of the de-
tor wells; wellpoints and/or sand drains if required;
watering facilities installed, and all significant opera-
pumps, engines, and piping; and related appurte-
tional, maintenance, and performance data and rec-
nances; and dikes, ditches, sumps, and pumps neces-
ords.
sary for control of surface water. The dewatering sys-
(4) Records. A copy of all inspection and test data
tems shall remain in continuous operation, as speci-
relating to materials, installation, operation and main-
fied, until completion of this (Phase II) Contract and
tenance, and performance of the dewatering systems,
the systems are transferred to the Phase III Contractor
and supplemental groundwater control facilities if
or to the Government.
any, as required, shall be promptly furnished to the
Contracting Officer.
b. Compliance with specifications and drawings.
G-8
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