TM 5-818-5/AFM 88-5, Chap 6/NAVFAC P-418
operation, maintenance, and any failure of any compo-
nances, and related earthwork necessary for the re-
nent of the system.
quired control of water. The sequence of installation of
components of the dewatering system shall be in ac-
d. Dewatering system.
cordance with the specifications and drawings. The
(1) Deep-well system. The clay and sand strata be-
system shall remain in continuous operation, as speci-
low elevation - 13.0 feet are continuous over a large
fied, until a written directive to cease dewatering oper-
area. Removal of soils above elevation - 25.0 feet. A
ations has been received from the Contracting Officer.
deep-well system shall be provided to relieve this pres-
(2) Control of water. The Contractor shall control,
sure. The pressure shall be relieved in the sand strata
by acceptable means, all water regardless of source.
such as those indicated on boring S-II-SS-1-62(A)
Water shall be controlled and its disposal provided for
from 67.5 to 72.0 feet and from 85.5 to 142.5 feet.
at each berm. The entire periphery of the excavation
These strata will vary in elevation and thickness over
area shall be ditched and diked to prevent water from
the area. The deep-well system shall be of sufficient
entering the excavation. The Contractor shall be fully
capacity to lower the hydrostatic head to elevation
responsible for disposal of the water and shall provide
-40.0 feet as measured in observation wells at nine
all necessary means at no additional cost to the Gov-
points in the excavation. One installed spare deep well,
ernment.
complete and ready for immediate operation, shall be
c. Design. The dewatering system shall be designed
provided for each two operating wells. The use of gaso-
using accepted and professional methods of design and
line prime movers will not be permitted in the opera-
engineering consistent with the best modern practice.
tion of deep wells. At each of the nine points two ob-
The dewatering system shall include the deep wells,
servation wells shall be installed. One observation well
wellpoints, and other equipment, appurtenances, and
shall be installed with the screen in the upper sands,
related earthwork necessary to perform the function.
and one observation well shall be installed with the
A representative of the Contractor shall visit the site
screen in the lower sands. The riser pipe for the obser-
to determine the conditions thereof. The Contractor
vation wells will be 2-inch pipe in 5-foot sections. One
shall be responsible for the accuracy of the drawings
of the observation points shall be constructed at co-
and design data required hereinafter.
ordinate N254 460, E260 065. The remainder of the
(1) Drawings and design data. The Contractor
observation points will be located by the Contracting
shall submit for the approval of the Contracting Of-
Officer after the dewatering plan is submitted. The ex-
ficer, within 30 calendar days after receipt of Notice to
act tip elevation of all observation wells will be estab-
Proceed, drawings and complete design data showing
lished after the dewatering plan is submitted; how-
methods and equipment he or she proposes to utilize in
ever, the tip elevation in the lower sand will be at least
dewatering, including relief of hydrostatic head, and
100 feet below original ground surface, and the tip ele-
in maintaining the excavation in a dewatered and in a
vation of the observation wells in the upper sands will
hydrostatically relieved condition. The material to be
be approximately 70 feet below original ground sur-
submitted shall include, but not necessarily be limited
face. The Contractor shall maintain the observation
to, the following:
wells and keep daily records of readings until other-
(a) Drawings indicating the location and size of
wise directed by the Contracting Officer.
berms, dikes, ditches, all deep wells, observation wells,
(2) Wellpoint system. A wellpoint system shall be
wellpoints, sumps, and discharge lines, including their
used above the top of clay shown on the borings at ap-
relation to water disposal ditches.
proximate elevation - 14.0 feet but to dewater the
(b) Capacities of pumps, prime movers, and
area from original ground surface to the top of the
standby equipment.
clay. This system shall have sufficient capacity to low-
(b) Design calculations proving adequacy of sys-
er the head within the excavation to the top of the
tem and selected equipment.
clay.
(d) Detailed description of dewatering proce-
dure and maintenance method.
e. Available soil test data and pumping test data.
The soil test data obtained by the Government are
(2) Responsibility. Approval by the Contracting
shown on the boring logs. Additional laboratory data
Officer of the plans and data submitted by the Con-
and samples of the soils from borings shown in the
tractor shall not in any way be considered to relieve
plans are available in the District office for inspection
the Contractor from full responsibility for errors
by bidders. Typical permeability data from laboratory
therein or from the entire responsibility for complete
tests at this site are tabulated. Pumping tests have not
and adequate design and performance of the system in
been made at the site; however, the soil profile at the
controlling the water level in the excavated area and
B-1 and B-2 test stand excavation is similar to this
for control of the hydrostatic pressures to the depths
site and this excavation is now being dewatered by a
hereinbefore specified. The Contractor shall be solely
deep-well system. Data on this system can be inspected
responsible for proper design, installation, proper
G-2
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