Jason is installing an observation well to determine if the heavy metals concentrations of the Ozark Aquifer are decreasing. To be sure that the observation well is free of influence from surface water, the observation well is sealed with an impervious cap. Jason uses a pelletized clay supplied by Bentoseal which was provided in convenient 10 mm diameter balls of dried clay. He drops the balls into the boring and just adds water. Voile! What clay do you think is best for this application and why? What causes the sealing effect he expects to happen? Would other clays produce similar results? Why?
As we all that their are various types of clay , which are listed below :
And also their are various other types of clay, depending upon their locations .
In case of heavy metal , puddle clay suits the best among all of
the mentioned above type because of its high proportion of
montmorillonite it was subsequently more widely employed for the
water-retaining element or core within earthfill embankment dams
until finally superseded in the latter application by the rolled
clay core from c. 1960. In the context of dam construction
satisfactory long-term performance of the puddle core is critical
to embankment integrity and hence to safety.
The earthfill embankment darn with a central puddle clay core.
commonly referred to in the UK as the Pennines type dam,has in
general performed satisfactorily in operational service.
It can be defined as a plastic soil, i.e. a soil with significant clay content. which has had its natural fabric and structure destroyed by intensive working and remoulding at a water content, w, such that the resulting clay puddle is soft, plastic, dense, homogeneous and of very low permeability. It is thus in principle a fill material well-suited to use in water retaining barriers such as darn cores or canal liners.
SEALING OF PUDDLE CLAY :
Lagoons for the storage or treatment of liquid wastes,
irrigation lakes, reservoirs etc. may all be sealed by similar
methods to those for waste facilities. As an example, Alston et al.
(1997) describe an effluent treatment lagoon at a pulp mill in
Ontario, Canada. A 300 mm thick base layer was required to have a
coefficient of permeability of less than and was constructed
from compacted sand bentonite mix, in the absence of suitable local
clay deposits. Extensive testing was conducted to arrive at an
optimum mix, which was subjected to permeation for over a year with
pulp mill effluent. No loss in performance of the material was
recorded. Existing facilities that are found to be leaking may
sometimes be sealed by simply addin bentonite to the water, and
allowing it to be drawn into the leaks.
SUMMARY
No other clay would be able to produce such kind of sealing and
longitivity , these clay are formed and also termed as plastic clay
. Various instruments can be used to check the stability and
effectiveness of this type of soil . The dry bentonite can swell by
10 to 15 times during hydration, ensuring good contact between
grout and soil. Instruments such as inclinometers and extensometers
which measure below-ground movements are usually grouted into
boreholes using cement bentonite mixtures; the proportions should
be adjusted to give a set stiffness of the grout similar to that of
the ground in which the
instruments are installed.
Hope so you would like my efforts , Please provide ratings . Thank You
Jason is installing an observation well to determine if the heavy metals concentrations of the Ozark...