Measuring and testing – Gas content of a liquid or a solid
Patent
1996-10-04
1998-07-28
Brock, Michael
Measuring and testing
Gas content of a liquid or a solid
7386474, 7386443, G01N 124, G01N 3324
Patent
active
057865272
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method and apparatus, and more particularly, relates to a method and apparatus for the testing of soil contamination.
The testing of soil for many reasons is well known in the art. One reason for such testing of the soil is to determine the presence of contaminants which may be the subject of environmental concern. For example, it is well known that a substantial amount of pollution has been caused by the leakage of tanks storing various liquids. One particular problem is the wide spread use of underground storage tanks for various petroleum products with it being known that many of these tanks leak due to corrosion and/or other reasons.
Many different types of proposals have been advanced in the art regarding the testing of the soil for contamination. One common type of testing involves the physical removal of a soil sample and forwarding of the same to a suitable laboratory for analysis. Disadvantages encountered with this method include the delays which are involved for the analysis of the samples and furthermore, the procedure normally involves a fairly substantial expense. Other known methods and apparati for the testing of soil are shown, for example, in U.S. Pat. No. 5,050,425 which shows an apparatus and method for measuring the presence of a volatile constituent of a sample of ground water or soil mixed with water. A different type of in-situ testing for contaminants is shown in U.S. Pat. No. 5,246,862 wherein a penetrometer is used to determine chemical contaminants in soil using calorimetric techniques.
A common problem associated with the known methods is the difficulty to determine the spreading or extension of the contamination efficiently and rapidly. Thus, while an absolute test may provide a certain reading, the reading is not necessarily indicative of the pollution extension insofar as its proximity to the actual source of pollution. Thus, assuming the example of an hydrocarbon leakage, the relative presence in a sample of the hydrocarbon does not necessarily indicate its proximity to the original source of pollution since migration of the hydrocarbon can and does occur.
A further problem which arises is that, even after the offending source of contamination has been identified, often a large amount of soil is removed to clean up the pollution. Again, when information is not known as to the degree of pollution, frequently more soil is removed than required resulting in substantially higher costs.
A further problem, particularly when evaluating the vapor or gaseous phase of a contaminant such as gasoline, is the inconsistency of results obtained. A concentration of organic vapors in a soil does not necessarily correlate effectively to the hydrocarbon contamination. The vapors can travel in the soil from the site of original contamination and can lead to false positive testing. Also, this testing does not necessarily give a direct relationship between the concentration of the organic vapor in the soil and the concentration of the hydrocarbon in the area.
U.S. Pat. No. 5,010,776 also discloses a method and system for detecting a contaminant wherein a probe collects a fluids sample from the contaminated medium. In the method, a fluid sample is taken by a carrier gas for analysis of the contaminant. The reference evaluates the partial pressure of the contaminant with a semi permeable membrane.
It is also known from U.S. Pat. No. 3,685,534 to circulate a fluid into repetitive contacts with soil and then measure the concentration of the selected fluid in the circulating fluid after a substantial period of time. A tool for accomplishing this is shown in U.S. Pat. No. 3,857,289.
For these reasons, the evaluation of organic vapors in the soil has, to date, only been considered a preliminary evaluation tool.
The displacement of the gaseous phase or vapor in a soil contaminated with hydrocarbons is influenced by many parameters such as the nature of the soil (its porosity, organic content, moisture content, the nature of the contaminant, etc.) When a liquid hydrocar
REFERENCES:
patent: 3685345 (1972-08-01), Wise
patent: 4335622 (1982-06-01), Bartz
patent: 4452091 (1984-06-01), Richers
patent: 4804050 (1989-02-01), Kerfoot
Brock Michael
Martineau Fran.cedilla.ois
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