1.7.4
Sampling for Geotechnical Analysis
Samples shall be taken of all materials penetrated by each drilled
well/test hole. Soil sampling shall be done with a [split] [thin-walled]
tube sampler using standard sampling techniques in accordance with [ASTM D
1586] [ASTM D 1587] Samples shall be extracted from their in-situ
environment in as near an intact, minimally disturbed condition as
technically practical. Samples shall be obtained continuously through the
area expected to be screened. The Contractor shall provide sieve analyses
of all drive-sampled material. Sieve analyses shall be conducted in
accordance with ASTM C 136. The gradation of the natural formation shall be
determined by the Contractor through the use of sieve analyses performed on
formation samples taken from the areas to be screened. Drive-sampled
materials shall be placed in airtight containers and labeled as specified
in paragraph SAMPLE CONTAINERS. Samples shall be delivered to the
Contracting Officer designated facility. Representative soil samples s
hall be tested for grain-size distribution by mechanical means (sieves down
to the 0.074 mm No. 200 size according to ASTM C 136), moisture content
according to ASTM D 2216 and Atterberg limits according to ASTM D 4318.
Description and identification of soils shall be done in accordance with
ASTM D 2488. Laboratory classification of soils shall be done in
accordance with ASTM D 2487. Sampling shall be performed to allow
completion of the documents described in paragraph BOREHOLE LOGS.
1.7.5
Observation Wells
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NOTE: In some cases an observation well or wells
should be drilled an appropriate distance from the
test hole or pump well. The observation wells
(piezometers) should be monitored during the yield
test of the test hole and/or capacity test of the
pump well so that valid information of aquifer
potential and character may be obtained. The
observation wells must be designed, installed and
removed from service in a manner that precludes the
possibility of future groundwater contamination
resulting from their existence. If the decision is
made to keep the observation well for future
sampling, or for use in future pumping tests, the
observation wells must be properly completed as
specified in this section, or other USACE guidance,
such as UFGS 02522A GROUND-WATER MONITORING WELLS.
When installing extraction, or injection wells at an
HTRW site, consideration should also be given to
leaving some observation wells inplace, to be used
for longterm operation and maintenance (O&M) of the
extraction, and injection wells
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After completion of the [test hole] [pump well] [_____], [1] [____]
observation well(s) [, or more as directed], at least [45] [_____] mm
[1-3/4] [_____] inches in diameter shall be drilled to the target water
bearing stratum, [at the location(s) indicated on the drawings] [at a
location [____] m [____] feet from]
[at an appropriate location near]
the [test hole] [pump well] [_____]. The observation well shall be used in
conjunction with the [yield test of the test hole] [and] [capacity test of
the pump well]. After final acceptance of the pump well by the Contracting
Officer, the observation well shall be [abandoned as specified in paragraph
SECTION 02521
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