TM 5-815-5/AFM 88-5, Chap 6/NAVFAC P-418
dewatering wells, pumps, piping, etc., required to con-
the deep and jet-eductors dewatering wells, the Con-
trol groundwater in the main excavated slopes around
tractor shall submit a plan of his or her procedures and
the excavation and in the deep sand stratum below the
equipment for accomplishing the work within fifteen
bottom of the excavation will be paid for as an extra.
(15) days of his or her Notice to Proceed. After receiv-
Any supplemental measures for control of seepage,
ing approval of such procedures and equipment, he or
whether perched or otherwise, in the bottom of the
she shall install and test the above dewatering system,
Phase II excavation or from excavated slopes in the
including unwatering the Phase I excavation, within
bottom of the excavation, will not be paid for as an ex-
120 calendar days. Any apparent deficiencies in the
tra.
deep or jet-eductor well systems for whatever cause
(a) The Contractor shall be responsible for: in-
shall be corrected within 15 calendar days after evalu-
stalling and testing the dewatering well and jet-educ-
ation of the pumping tests made on the systems and
tor system as specified prior to and after unwatering
notification by the Contracting Officer. There shall be
the Phase I excavation; unwatering the Phase I excava-
no unwatering of the Phase I excavation until the
tion; dewatering and/or controlling any seepage from
deep-well system has been installed and tested, and no
specified excavated slopes or in the bottom of the exca-
unwatering of the excavation more than 3 to 5 feet be-
vation so as to prevent any raveling or other instabili-
low any reach of the uppermost berm, where jet-educ-
ty of the slopes while unwatering of the Phase I exca-
tor wells are to be installed, until all of the jet-eductor
vation and driving the test and foundation piling un-
wells specified are installed.
der this contract; maintaining the hydrostatic water
(5) Testing dewatering system. After the deep-
level in the deep sand formation at least 5 feet below
well dewatering system has been completely installed,
the bottom of the excavation and any excavated
its adequacy shall be checked by the Contractor mak-
slopes, and controlling any detrimental seepage
ing a pumping test on the entire system, as directed by
emerging from pervious soils in the top stratum; low-
the C.O.R., prior to unwatering the Phase I excavation
ering the groundwater table in pervious or semiper-
and at the completion of unwatering the Phase I exca-
vious strata in the top stratum at least 3 feet below
vation. The jet-eductor systems shall be continuously
any excavated slopes except at the contact with an un-
operated while unwatering the Phase I excavation and
derlying impervious stratum; maintaining the bottom
the adequacy of its performance evaluated after com-
of the excavation free of all seepage or surface water
pletion of unwatering and as the excavation for Phase
until the end of this contract; and operating and main-
II is carried to grade. The performance of the dewater-
taining the dewatering systems.
ing systems will be evaluated by the Government. If
(b) The Contractor shall be responsible for in-
the dewatering well system and jet-eductor wells are
stalling and operating continuously the dewatering
found to be inadequate to control the groundwater and
well systems specified herein, and any other supple-
artesian head below the excavation, they shall be sup-
mental wells, pumps, and engines, necessary to lower
plemented as provided for subsequently in these speci-
and maintain the hydrostatic head in the deep under-
fications.
lying sand formation 5 feet or more below any Phase II
(6) Operation during contract. The Contractor
excavation, and with the capacity of lowering the
shall operate and maintain the specified dewatering
groundwater table below elevation -29.0 feet in the
well and jet-eductor systems and any supplementary
chamber and elevation -35.0 feet in the gate bay
wells or seepage control measures that may have been
areas for the lock, for a projected Red River stage of
installed, as needed to comply with these specifica-
elevation 60.0 feet. The Contractor shall also be re-
tions during the complete period of this contract.
sponsible for maintaining the groundwater table in
(7) Transfer of dewatering system to Phase III
silt, silty sand, and sand strata, penetrated by the
Contractor. Upon completion of this contract, the Con-
Phase I or Phase II excavation at least 3 feet below the
tractor shall turn over the complete deep-well, jet-
surface of the slope, and shall control any seepage at
eductor, and surface water control systems and all
the contact between seeping soil strata and impervious
standby equipment to the Phase III Contractor or the
strata occurring at any time which might otherwise
Government who will at that time assume ownership
cause raveling or instability of the slope at that level.
and operation of the dewatering and surface water
Any noncompliance with the above specified ground-
control systems. The Phase III Contractor will be re-
water control requirements shall be promptly rectified
sponsible for removal of the systems in accordance
in accordance with these specifications.
with his Phase III contract.
(c) The Contractor shall be responsible for all
(8) Unwatering excavation for Phase I contract. It
damage to work in excavated areas caused by failure to
will be the responsibility of the contractor to unwater
maintain and operate the dewatering systems as speci-
the excavation made during the Phase I contract for
fied.
this project. No unwatering of the excavation shall be
(4) Installation sequence. Prior to installation of
started until after the deep-well and jet-eductor dewa-
G-10
Previous Page
