CA2125034A1 - Process for the local treatment of soil in particular for examination and cleaning of contaminated soil - Google Patents

Abstract

Abstract Process for the local treatment of soil in particular for examination and cleaning of contaminated soil The invention relates to a process for the local treatment of soil, in particular for examination and cleaning contaminated soil, in course of which the ample taken from the soil resp. contaminated liquid coming from the contaminated soil or contaminated soil-water are delivered to the surface; prior to delivery or thereafter some treating medium and/or any other material converting the contamination is introduced into the soil intended to be treated or into the contaminated soil.
The process according to the invention is characterized in that oblique angled connecting pipes (4,5) resp. a perforated pipe-system (6a,6b) connected thereto, consisting of uniform circuits or streaming circuits, are laid, fitting to the dominant position of the contaminated layer or the layer intended to be treated, so for example occupying a horizontal position, wherein one branch (6a) of the system collects the contaminated liquid, contaminated soil water for further delivery, while the other branch (6b) of the system delivers treating medium and/or cleaning media or clean water into the contaminated soil-layer (1).
The pipe system consisting of the oblique angled pipes (4,5) and the perforated pipes (6a,6b) connected thereto, is drawn -each single pipe-section (4,6a, resp. 5,6b) in itself- in the bores, having been drilled by known drilling technologie, by pulling back the drilling machine forming said bores, thereafter the bore is starting from the surface, penetrates the contaminated mass of the contaminated soil and after having left the mass it appears on the surface, thereafter the single pipe-sections (4,6a, resp. 5,6b) are connected one by one with the drilling machine.

Description

~12~3~l The invention relates to a process for the local treatment of soils in particular examinig and cleaning of contaminated soil.
The process according tn the invention is primarly recommended for soils having been contaminated with chemicals or crude oi] resp. derivates of mineral oil, where depth of contamination may be calculated to several meters.
Such contaminations might and can be recorded with e.g.
industrial plantes, fuel bases, oil (petroleum) raffineries and in the environments of military objects.
Differently from the aforementioned places contamination of soil can be reckoned with on other places sn e.g.
alon~ traffic lines, so in case of accidents.
Danger of the enumerated soil contaminations is considerably significant. This becomes unambigollsly obvious, if we consider that soil contamination will appear, directly or indirectly, however at all means, in our food; therefore it is of utmost important ~to eliminate contamination using most efficient methods, at least we should endeavour to minimize detrimental effects.
Local treatments of soils belong also to the scope of ` 212t~3-l invention. This can be carried ollt with or without simultaneous cleaning. In sense of the invention all activities belong to the scope of the invention, in course of which soil will be influenced in mechanic or chemical sense.
We are of -the opinion that the process according to the invention will be used in the maJority of cases for soil cleaning, so in the following we intend to detail accordingly the cleaning method. It goes withollt saying that this does not mean the restriction of use to cleaning possibility.
~e may distingvish two versions of possible methods, namely exchange of soil and locally performed cleaning.
Our invetion belongs to the latter activity, that means we offer a new solution of local soil cleaning.
In course of known processes of soil cleaning one proceeds in so far as vertical bores are drilled in the contaminated layer and in dependence of the natlJre of the contamination through said bores detergents with cleaning effect, bacteria cultllre or air used to be introduced into the contaminated layer. Efficiency of the method can be modified by changing the frequency of tne arrangement of bores and by increasing the permeability of the conatminated layer by explosion. However increment of efficiency effected by changes is rather limited.

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Characterizing example for known solutions can be found in the periodical "Wasser Luft, Boden" (1990.No.11-12, Page 94-95). The example relates to a method for in-situ rehabilitation of soils having been contaminated with volatile chlorinated hydrocarbons. When operating with said method soil-air is sucked through vertical bores.
(For the sake of order it should be mentioned that from the point of wiev of interpretation of the invention under liquid every kind of fluidum, taken in a wider sense, are to be understood, so also gaseous media.) An other example may be found in the aforementioned periodical (pages 90-91). The solution discussed here relates to soil-washing with high pressure.
In course of the process as specified in the European Patent Al,0 170 B62 after having exchanged soil representing the essence of the invention - into the not cleaned part of the contaminated soil cleaning liquid is introduced through vertical bores. Farther from the place of introduction through one or more vertical bores suction effect will be induced.
With these solution the inventors have not arrived at the recognition in so far as soil washing carried out through individua] bores as well as soil cleaning exert but a local effect and they are unsuitable for the uniform treatment of contamination of larger volume.

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Known solutions, not only the above mentioned ones, show several disadvantageous features. One of the disadvantages appears therein, in so far as only single type of soil cleaning can be realized. It is impossible to apply simultaneously or parallel biologic, physica]
and chemical methods on a given place but in different depths.
An other disadvantage appears therein that due to vertical bore the method cannot be performed on several places. It becomes quite obvious that it is impossible to penetrate - using vertical bores - into soil layer lying under buildings, beds of water stream, slopes and several other cases.
It is a well known fact that three states of oily soil contaminations resp. contaminations of chemica] nature can be distinguished; namely the bound form, the released form and the free form. In case of a contamination appearing in bound form biologic c]eaning seems to be the most expedient. Against soil contaminations being present in a released state, chemical methods seem to be the most efficient. Soil contaminations occurring in a free form may be cleaned with the highest efficiency by using physical methods.
The aim of our invention has been to provide for a solution which can be generally used while different 2 12 ~

treating and/or cleaning can be applied in combination.
The process according to the invention reaches the aim set primarily due to the arrangement in which a perforated pipesystem,connected to pipes laid in oriented drilled borings is used occupying a position being in compliance with the dominant direction of the contaminated layer, serving for collecting both the contaminated liquid and contaminated soil water and delivery thereof, furtheron for the introduction of different treating and cleaning media into the designated layer.
Under the mentioned dominant direction of the spatial position of the majnrity of the relevant layer is meant.
So for example any layer can be considered as a horizontal layer if the majority of its mass is lying in the horizonta~ zone, altough single sections may slope.
In the case of the aforementioned pipesystem is considered as horizontal in sense of the process according to the invention. It goes without sayin~q that the pipesystem is connected to oblique angled pipes, thus staying in connection with surfacial equipments, so far example with a pump.
The pipesystem is installed in bores having been formed by the oriented boring technologie, known in itself, without demolation of the soil or the establishments " ~ ~ ' ' ' ' .' ""

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lying above the contamination. ~n one branch of the pipesystem, arranged in the bores and consisting of perforated pipes, treating media is introduced. The other branch of the pipesystem carries the liquid including contamination onto the surface. The pipesystem is designed so as to enclose the full mass of the contamination. Shape and frequency of arrangement of perforations can be varied resp. chosen in compliance with local conditions.
From the point of view of the fluid technics the pipe system may consist also of a plurality of streaming circuits in which simultaneously different processes may take place. According to experiences having been gained up to now the plpesystem may be installed in a depth ~o 10 meters in general without causing problems.
For the pipesystem as well for connecting pipes synthetic pipes, known in itselves, with a diameter expediently to 200 mm can be used.
As specified in the European Patent EP,Al,0 228 626 (page 8, ab line 34) a perforated pipe system sunk into the soil is provided for the removal of contaminated liquid, however -introduction of the cleaning medium is taken ., .

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~, 2~n34 place by sprink]ing and spraying guided from the surface (page 8, lines 35-45). Efficiency of introduction of cleaning medium from the surface by sprinkling, spraying is far inferior to our solution, in sense of the recognition of the invention, as the oriente~
introductinn by means of pipesystem assembled of perforated pipes, appearing in the inventive conception, is far more efficient as it encloses the full mass of contamination.
In the Patent Dl,A1,3 83~ ~50 a system is specified which is placed under the deponies prior of filling and which is well suitable for the treating of later arising contamination. The drainage piping arranged under the deponia collects and delivers the contamination carrying liquid and discharge it on the surface. Treating medium, optionally moistening, is sprayed, sprinkled on the upper surface of the deponia. (Claim 1.) A possible upper pipesystem is also mentioned, but in connection with Claim 1. introduction of treating media guided from above in an irregular stream is characterized therein.
All these differ in respect to two fundamental characteristics from the invention. At first the pipesystems have to be established preliminary, as a consequence the systems are unsuitable for the removal of any contamination arising on a not fnreseen place, at ,,; ,, ~, - . ~ . .

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- 2~2~034 second the importance nf the effect to be achieved by the oriented introduction of the treating medium into the contaminated layer has not been recognized yet; the problem can be solved by the pipesystem according to the invention consisting of peforated pipes and enclosing the full mass of the contamination.
Out of the known solutions alone the method according to the European Patent EP,Al,O 17~ ~62 is well suitable for treating contaminations arised on a not forseen place, but is does not give efficient means for enclosing the full volume of contamination, as the vertical wells established for the introduction of treating media and removal of contamination, even if arranged densily, are at no means equivalent with the pipesystem assembled of perforated pipes in accordance with the invention.
Further fundamental difference lies in, that by means of the vertical wells, contaminations under huildings cannot be treated without demolishing already existing buildings. In contrast to it by operating the pipesystem consisting of perforated pipes arranged in oblique bores can be established without demolishing of soil and buildings.
The apparatus according to the invention, consisting of perforated pipes and the connected charging and discharging pipes, differs from other solutions, like the .. , . ., , ~ .. - , ~ . - .. - - ~

-- 212~34 drainage system according to OE,Al,383 85n, in so far as after formation of contamination, if soil cleaning is required, the drainage system can be established subsequently only on any optional p]ace.
In sense of the method according to the invention contamination of the contaminated layer and/or the layer intended to be cleaned will be examined directly or indirectly. Examination can be carried out continuously or discontinuously. One possible method of direct examination lies in that vertical observing wells are drilled independently of the pipesystem, while the signals of the sensors having been built-in in the wells are processed on the surface. Conditions prevailing in the examined layer are tested in laboratories by analysing the samples. It becomes possib]e to perform indirect examinations f.e. in so far as contaminated soil water having been collected in the pipesystem and delivered to the surface is subjected to analysis. From the result of analysis we conclude on the fnrmation of soil contamination. Another possible method for testing contamination lies in that a carotage cable should be installed into the pipesystem or to a part thereof and by means of measuring unit connected to the carotage cable hole-geophysioal measuring is carried out.
In the sense of the invention not only a carotage probe -- 212~34 1 ~

can be installed into the oblique angled and horizontal pipesystem but any other probe or instrument. By means of said units physical, chemical and biological change can be registered in the examined layer, simultaneously stability thereof can be also checked.
Introduction and suc~ing back of the cleaning medium take place in the necessary depth, the process can be well controlled, the liquid does not spread into other layers.
By means of the oblique angled and horizontal pipesystem core-samples are available. By the analysis thereof in laboratories more accurate information will stay at disposal. In such a manner core-samples will be available not only from vertical bores.
We may clean the contaminated soil-water having been delivered onto the surface, while the contamination itself and optionally the contaminating liquid can be led to a closed safe place simultaneously meeting all requirements of ecology. Generally it seems to be expedient to recirculate the cleaned soil-water into the aforementioned contaminated layer.
After having cleaned the contaminated layer the installed pipesystem can be utilized so, in so far as it is used as an observing system, furtheron in case of necessity, following cleaning the system will not be demolished but ~12~1~34 it is kept in operation as a monitoring system.
In course of soil cleaning the system is well suitable for using biological cultrures within an enlarged scope.
In case if cultures are applied in the proximity of soil-water and processes tend to occupy an undesirable direction (excess proliferation of bacteria) by means of a parallel establihed system according to the invention immediate intervention becomes possible so, for example by freezing, change of pH-value; by said intervention undesired biological function of bacteria can be hindered.
Accordingly the essntial feature of the process according to the invention lies is that we install oblique angled connecting pipes and a perforated pipesystem connected thereto, fitting to the dominant position of the contaminated layer resp. to the layer intended to be treated, so occupying the horizontal position, consisting of uniform pipes or streaming circuits. In one branch contaminating liquid or contaminated soil-water is collected and delivered, while in the other branch treating means and/or cleaning means and/or fresh water will be introduced into the contaminated layer.
With an expedient method of performance of the process according to the invention contaminated soil-water having been delivered to the surface is ana]ysed continuously or discontinuously.
It seems to be expedient to proceed so, that the contaminated layer resp. the layer intended to be treated is examined independently of the pipesystem by means of an observing well. ~ -A preferred method of the process according to the invention lies in, that the treated resp. contaminated layer is examined by means of a carotage cable installed into at least in a part of the pipesystem, or sensor and/or measuring element connected to a surfacial measuring unit.
In accordance with the invention it becomes possible to clean the contaminated soil-water delivered onto the surface in situ, whereafter clear water is recycled into the contaminated layer.
In course of the process according to the invention as cleaning medium we may ose bacteria-culture and/or chemicals.
The process according to the invention will be detailed in connection with a preferred embodiment making reference to the drawings enclosed.
- Figure 1. illustrates the pipesystem consisting of the oblique angled charging pipes and the thereto connected perforated-pipes, needed for realizing the process according to the invention, as well as the ~ 2aO3~

pumping, measuring and controlling devices, shown in a broken part of ~he contaminated masse;
The Figure 1. shows the fractional view of the soil illustrating the necessary means needed for realizing the process according to the invention. In the case illustrated here the contaminated layer 1 lies below the top coverlayer 3; below the layer 1 the impermeable layer 2 is to be found. The contaminated layer 1 as permeable layer contains the contamination itself. In order to eliminate contamination we establish the pipesystem 6a, 6b, being composed of perforated pipes, without demolishing the soil by using one of the known methods of laying pipes in drilled horizontal bores. From the embodiment serving as an example illustrated here it becomes obvious that the dominant position of the contaminated layer 1 intended to be cleaned is horizontal, accordingly the pipesystem 6a, 6b serving directly for cleaning occupies also a horizontal position. Complete layout of the pipesystem 6a, 6b is not detailed in the drawing, however for the sake of order it - ~2~n3~

should be mentioned, that the system may be composed of several streaming circuits, these streaming circuits may be interconnected, but it is possible to form also individual circuits.
The pipesystem 6a illustrated here is connected via the oblique angled connecting pipe 4 to the pump 7, while the oblique angled connecting pipe 5 connects to the tank 8. Pump 7 delivers the contaminated soil-water from the contaminated layer 1 to the reactor 9; thereafter the cleaned soil-water arrives at the tank 8, wherefrom it is discharged into the pipesystem 6b, being composed of perforated pipes, through the connecting pipe 5.

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With the embodiment serving here as an example the observing well 10 is built independently of the pipesystem 6a, 6b.
An in itself known probe or carotage cable or other sensing means are installed into the well; signals coming from these are evaluated by means of observing organ 11. In such a manner from results of continuous or d1scontinuous exa~inations we shall be well informed on the cleaning process of the contaminated layer 1.
Examination resp. control may be carried out so in so far as carotage cable is built-in into the pipesystem 6a, F.

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6b or into a section thereof, the signals thereof are processed on the surface with proper means well known in itselves, in order to be able to follow and observe changes in contamination.
Similarly to the embodiments serving here as an example in addition to the aforesaid pipesystem 6a, 6b another pipesystem can be installed through which bacteria culture or any other chemical detergent can be introduced into the contaminated layer 1.
It becomes possible to realize the process according to the invention so, in so far as tne pipesystem illustrated here is used periodically partly for introducing the bacteria culture or chemical cleaning media, partly for delivering contamined resp. cleaned snil-~Jater.
In case if the contamination had a special character or it is arranged so that in a liquid state it fills a predetermined space, by means of the pipesystem 6a, 6b having been installed, from said space liquid contamination can be delivered directly onto the surface.
From all what have been said it becomes obvious that in course of the process according to the invention in best kno~Jledge of the in-situ conditions the most efficient method can be chosen and in course of the applicaiion the most advantageous chemical and biological composition, concentration can be adjusted. The hole geophisics, to be ?~

2~034 realized by the horizontal pipesystem, throws can be accurately defined and lay-bounderies laying next to the s(lrface can be easily determined.
From the example enumerated it becomes obvious that by peforming the process according to the invention physical, chemical and biological soil cleaning can be used separately but simultaneous combination thereof can be reali7ed too. In consideration of the invention choice of the appropriate version depends on the geological situation and quality of contamination.
ûn basis of the experiments carried out with the process according to the invention and the results gained it can be unambigously stated that just by means of the horizontal pipesystem efficiency is better by an order of magnitude in comparison to earlier solutions serving for the same purpose.
In course of the process according to the invention, compared with known solutions specific cost may be reduced in certain cases to the one fifth, one tenth thereof.
The pipesystem applied in course of the process according to the invention serves for severa] purposes in connection with subsurfacial soil layers. Let us mention some examples which could be covered with the expression "treatment". In course one of the methods by allowing ',js~ " ~
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liquid nitrogen circulate the liquid in the snil and pores can be frozen upto a depth of several meters. With another mode of perfomance thermick treatment becomes possible; by this method hydrncarbons may be rendered volatile. The process is well suitable for neutralizing heavy metals if such are present in the contamination. In this case including material can be rejected into the subsoil resulting in the waterinsolubility of heavy metals.
In addition to the accessory advantages of the process according to the invention the main adavantage lies in that it can be well used in places where performance of traditional technologies become impossible, so far as example soil contamination occuring in subsoil can be eliminated, so under plants, factories, lakes and rivers or between densily arranged objects.
For the sake of order it should be mentioned that the process according to the invention can be combined with traditional technologies operating with vertical bores.
This version and circumstances increase multible versability ~f the process according to the invention and emphasize adaptibility to different conditions.

Claims (8)

Claims

1. Process of the local treatment of soils, in particular for examination and cleaning of contaminated soils, in course of which soil sample resp. contaminated liquid coming from the contaminated soil-layer or contaminated soil-water are delivered onto the surface, prior to the delivery or thereafter treating medium and/or the contamination conversing detergent is introduced to the contaminated layer resp. into the layer intended to be treated characterized in that without demolishing the soil through oriented drilled borings oblique angled connecting -pipes (4,5) and connected thereto a perforated pipesystem (6a,6b) are laid which pipesystem (6a,6b) occupies a horizontal position, fitting to the dominant position of the contaminated layer (1) resp. to the layer intended to be treated, the pipesystem (6a,6b) consisting of uniform or several streaming circuits, while in one part of the pipesystem (6a) contaminating liquid or contaminated soil-water are collected and delivered theretrough, in the other part of the pipesystem (6b) liquid, cleaned from the contamination, in recirculation and/or treating medium and/or clean water are introduced into the conatminated layer (1).

2. Process as claimed in Claim 1. characterized in that in case if we intend to perform cleaning below already existing plants, deponies, perforated pipesystem (4,5,6a,6b), delivering cleaning liquids, contaminated liquid or soil-water are installed subsequently without demolishing contaminated soil or buildings above the contaminated soil in bores formed by oriented drilled borings.

3. Process as claimed in Claim 1. characterized in that contaminated soil-water having been delivered to the surface will be analyzed continuously or discontinuously.

4. Process as claimed in Claim 1. characterized in that contaminated layer (1) resp. the layer intended to be treated is checked independently of the pipesystem (4,5,6a,6b) by means of an observing well (10).

5. Process as claimed in any of the Claims 1. to 4.
characterized in that the treated or contaminated layer (1) will be examined by means of a carotage cable installed into at least in a part of the pipesystem (6a,6b) and connected to surfacial measuring unit and/or by sensing organ and/or measuring element.

6. Process as claimed in any of the Claims 1. to 5.
characterized in that the pipesystem (4,5,6a,6b) delivering the cleaning medium, the contaminated liquid or soil-water is operated as an observing system after having performed soil cleaning.

7. Process as claimed in any of the Claims 1 to 6 characterized in that contaminated soil-water having been delivered to the surface is cleaned, thereafter clean water is recycled into the contaminated layer (1).

8. Process as claimed in any of the Claims 1 to 7 characterized in that as cleaning medium bacteria culture and/or chemical agents are used.