Measuring and testing – Gas content of a liquid or a solid
Reexamination Certificate
1999-10-05
2001-09-18
Williams, Hezron (Department: 2856)
Measuring and testing
Gas content of a liquid or a solid
C073S019120, C073S864740, C073S864330, C073S864430, C175S059000, C175S064000
Reexamination Certificate
active
06289714
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for testing soil contamination in situ.
BACKGROUND OF THE INVENTION
The parent U.S. application Ser. No. 09/11 8,888 (hereafter the '888 application) filed by the present applicant discloses a method for testing the soil contamination by ejecting a circulation fluid in the soil, with a very small proportion of a tracer fluid. Fluid samples are simultaneously collected wherein contaminant fluid concentrations and tracer fluid concentrations are measured and used for computing the effective flow rate Q′, in the affected soil volume. The tracer gas is used to circumvent the fact that the value of the affected soil volume is not known. With the effective flow rate Q′, the generation rate G of the contaminants in the soil can be computed. With this method according to the '888 application, the use of a tracer gas is compulsory.
Also, according to the method described in the '888 application, the circulation fluid is ejected into the soil by the probe at a greater flow rate than the fluid intake flow rate. This results in a local increase of the quantity of fluid near the probe tip, which creates fluid pressure differentials in the soil. The contaminant fluids will consequently be prone to migrating in the soil according to fluid pressure gradients instead of migrating according to fluid concentration gradients.
U.S. Pat. No. 3,685,345 issued in 1972 to Harold L. Wise, commented in the Background of the Invention section of the '888 application, shows a soil sampling apparatus including an outlet tube and an inlet tube each having an opened lower extremity located near the bottom of a hole having been drilled in the ground. A circulation fluid is ejected from the outlet tube lower opening, and the circulation fluid mixed with a proportion of contaminants is collected by the inlet tube lower opening. However, in the Wise patent, the entire hole is not subjected to the circulation fluid, since the fluid ejection and collection both occur near the lower extremity of the hole. Thus, it is not possible with the method described in the Wise patent, to determine an approximate affected soil volume to be used to compute the generation rate of contaminants in the soil. In any event, the object of the Wise method is not to verify the contaminant generation rate, but to verify the concentration of the contaminant fluid.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide a method for testing soil contamination without the use of a tracer fluid, and thus by ejecting only a single fluid in the soil.
It is an object of the present invention to provide a method for testing soil contamination by injecting a circulation fluid in the soil, while maintaining a substantially constant fluid pressure in the area where testing occurs.
It is a further object of the present invention to provide a probe for testing soil contamination.
SUMMARY OF THE INVENTION
The present invention relates to a method for locally testing underground soil contamination by determining the generation rate of a first contaminant fluid in porous soil, said method comprising the steps of:
a) making a hole of known dimensions in the soil;
b) covering the hole, so as to define a closed cavity of known volume;
c) constantly ejecting a second fluid in said cavity, at a constant given flow rate;
d) simultaneously continuously collecting fluid samples from said cavity at a location therein away from where said second fluid is ejected, at said constant given flow rate, to create a circulation flow of the second fluid in the entire cavity;
e) measuring the concentrations of said first contaminant fluid from at least three of said fluid samples collected at known time intervals; and
f) computing the generation rate of said first contaminant fluid, from the known volume of the cavity and from the concentrations measured in step (e) originating from samples collected at the known time intervals.
The present invention also relates to a method for locally testing underground soil contamination by determining the generation rate of a first contaminant fluid in porous soil, said method comprising the steps of:
a) making an elongated hole of known dimensions in the ground soil, with the hole defining a first and a second spaced-apart end portions;
b) covering the hole, so as to define a closed cavity of known volume;
c) constantly ejecting a second fluid in said cavity, at a constant given flow rate, near either one of said upper and lower end portions of said cavity;
d) simultaneously continuously collecting fluid samples from said cavity, at said constant given flow rate, near the other one of said first and second end portions of said cavity;
e) measuring the concentrations of said first contaminant fluid from at least three of said fluid samples collected at known time intervals; and
f) computing the generation rate of said first contaminant fluid, from the known volume of the cavity and from the concentrations measured in step (e) originating from samples collected at the known time intervals.
Preferably, the method further comprises, between step (a) and step (b), the step of inserting into the hole a hollow probe, wherein said probe extends from said cavity first portion to said cavity second portion and has a second fluid outlet opening at said cavity first portion and a first fluid inlet opening at said cavity second portion, said outlet and inlet openings being respectively connected to inlet and outlet conduits, the fluid ejection in step (c) being accomplished through said outlet conduit in said hollow probe and the fluid collection in step (d) being accomplished through said inlet conduit in said hollow probe.
Preferably, the method further comprises before step (a), the steps of driving through the soil a hollow probe and partially retracting said probe to make the hole according to step (a) and to simultaneously cover the hole according to step (b), the probe then extending from said cavity first portion to said cavity second portion and having a second fluid outlet opening at said cavity first portion and a first fluid inlet opening at said cavity second portion, said outlet and inlet openings being respectively connected to inlet and outlet conduits, wherein the fluid injection in step (c) is accomplished through said outlet conduit in said hollow probe and wherein the fluid collection in step (d) is accomplished through said inlet conduit in said hollow probe.
Preferably, said second fluid is a substantially inert gas, and advantageously this second fluid is a gaseous fluid selected from the group comprising helium, argon and nitrogen.
Preferably, said known time intervals are regular time intervals.
The present invention further relates to a probe for testing soil contamination, comprising:
a rigid main body having an inner conduit defining a lower opening and a first and a second top openings;
an inner tube coaxially located inside said inner conduit and of lesser diameter than said inner conduit, so as to allow fluid passage in said inner conduit about said tube, said inner tube extending upwardly out of said rigid main body through said first top opening and defining a top opening outwardly of said rigid main body, said inner tube further defining a lower opening;
a seal mounted to said main body at said inner conduit first top opening, to prevent fluid passage out of said inner conduit through said inner conduit first top opening about said inner tube;
wherein either one of said inner conduit second top opening and said inner tube top opening is adapted to be connected to a circulation fluid source, while the other one of said inner conduit second top opening and said inner tube top opening is adapted to be connected to a fluid sample collecting device; and wherein said inner tube is axially slidable in said inner conduit between a retracted position, in which said inner tube lower opening is located inside said inner tube, and an extracted position, in which said inner tube lower opening projects out of
Martineau Francçois
Wiggins David J.
Williams Hezron
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