RU2301862C2 - Method to create cutoff curtain with filtering openings - Google Patents

Abstract

FIELD: ground water and opened water stream protection, particularly to trap contaminated ground water streams from industrial waste accumulation ponds and livestock complexes, as well as oil and oil product spills from oil storages, petrol stations, to prevent insecticide conveyance from irrigation fields.

SUBSTANCE: method involves excavating trench; inserting lining made, for instance, of wood, metal or plastic in the trench; filling the trench with hardening impervious material; removing the lining from the trench; filling created openings with sorbing-and-filtering or deactivating-and-filtering substance by insertion of removable cartridges therein. The cartridges include box-like cases covered with mesh web material and filled with above substance.

EFFECT: increased efficiency of contaminated ground liquid flow cleaning.

2 cl, 6 dwg

Description

The invention relates to the field of protection of groundwater and open watercourses. It is designed to intercept contaminated ground flows from storage ponds of industrial waste, stockpiles of livestock complexes, oil and oil products leaks from oil storage tanks, gas stations, and the removal of pesticides from irrigation fields such as pesticides, ammonium and nitrate nitrogen, phosphorus, potassium, etc.

Groundwater pollution is not limited to the area of industrial enterprises, waste storage facilities, etc., but spreads downstream to a distance of 20-30 km or more from the source of pollution. Pollutants are carried out by a soil filtration stream to open watercourses (river, pond, pond, etc.).

The content of radioactive substances in the water causing radioactive contamination is very dangerous. Radioactive elements with increased ability to move in water like strontium-90, uranium, radium-226, cesium, etc. also fall into groundwater.

A known method of creating anti-filtration curtains (PFZ) in the soil from hardening aggregates made in a continuous way, i.e. development and filling of the trench with antifiltration material (PFM) without dividing into sections [1. Underground structures constructed by the “wall in the ground” method. / Ed. Cand. tech. Sciences V.M. Zubkova. L., Stroyizdat, Leningrad Branch, 1977, S.93-101.

2. Methodological recommendations for the design and construction of monolithic buried parts of hydraulic structures and air curtains using the “wall in soil” method. [Min. Meliorats. and water. households USSR “Soyuzorgnvodstroy”, Research Institute of Foundations. and sub. coop. Gosstroy USSR N.M. Gersevanova. M., 1981, pp. 48-55].

3. Osadchuk V.A. Experience in installing anti-filter trench curtains from various materials. [Hydrotechnical construction No. 1. 2004, S.30-34].

The disadvantage of this method is that when creating an impermeable curtain against the path of movement of a polluted stream, water is created which causes a rise in the level of groundwater, waterlogging, etc.

In addition, high pressure gradients arise in front of the PFZ, which exceed the critical gradients, which is why it is required to use PFM with higher anti-filtration properties when using the PFZ device.

The technical results achieved by the present invention is that the filter windows do not create a backwater groundwater, but pass and at the same time clean them from harmful impurities, lighten and deactivate the contaminated ground stream.

The method of creating impervious curtains with filter windows is illustrated by drawings, where Figs. 1a - 1d show variants of impervious curtains with filter windows.

On figa presents PFZ in the soil, arranged up to the stopper, and in the lower part of the curtain there is a filter window filled with sorbent-filtering (SF) material, where: 1 - PFZ; 2 - filter window in the curtain.

With this arrangement of filter windows, a contaminated stream, such as oil, is concentrated before PFZ-1.

In order not to back up and raise the groundwater level, unpolluted (clean) water is discharged through the filter windows 2 in the lower part of PFZ-1. If the contaminated water stream is formed due to contamination with substances soluble in water, then the PFZ must be filled with the corresponding SF material.

On figb filtering windows are arranged in the upper part of the PFZ and filled with SF material. When a contaminated stream of water passes through the filter windows, it is cleaned. After working off the SF, the material can be removed and used in construction, and the filter windows are filled with new SF.

With this arrangement, removable cartridges in the form of a box-shaped frame covered with a mesh cloth and filled with SF or deactivating-filtering (DF) material can be used in filter windows.

On figv PFZ is completely filled with SF material and is designed to clean the contaminated stream throughout the depth. Depending on the material, SF material can be used to clean any contaminants.

In Fig.1g PFZ is performed with filter windows in the upper and lower parts. In this case, the water is purified from pollutants in the upper part and the passage of clarified water in the lower part.

On fig.1d filtering window with SF material is arranged in the middle of the PFZ; this makes it possible to maintain the groundwater level at a depth of 15-20 m, without creating swamping, to let water from the buried layers in the event of a contaminated ground stream concentrated in the upper layers (for example, an oil stream).

Figure 2 presents a section of PFZ with filtering windows: 1 - PFZ; 2 - filtering windows; 3 - winch; 4 - coper; 5 - vibration absorber; 6 - solution supply; 7 - immersed element.

The method of creating anti-filter curtains with filter windows is as follows.

After the development of the trench by dragline excavators, scraper trenchers, backhoe shovels, clamshell installation (figure 2) and others arrange PFZ of hardening or non-hardening aggregates. Dumping in a trench of lump clay, clay soil is made with a grab.

Before introducing into the trench aggregate through the calculated distance in the air curtain 1 (figure 2) insert liners made of wood, plastic, metal, etc. After making and hardening the aggregate, the liners are removed and filter holes 2 are arranged in the voids formed, which fill the SFM, for example, fly ash, glauconite sand, etc., as well as, if necessary, a decontamination-filtering (DF) material, composition, etc.

In some cases, to increase work efficiency, removable cartridges are built into the filter windows 2 in the form of a box-shaped frame covered with a mesh cloth and filled with sorbent-filtering (SF) or deactivating-filtering (DF) material, composition, etc.

For removable cartridges, for example, the already existing BENTOMAT - geosynthetic bentonite material based on sodium bentonite can be used. It is used in the construction of anti-filter screens (PFE) to protect soil and ground water from various pollutants, in the construction of landfills for solid household waste (MSW) or solid industrial waste (TPO), storage tanks for oil and fuels and lubricants (fuel and lubricants), gas stations stations (gas stations), industrial and decorative reservoirs, during the reclamation of landfills, during the disposal of wastes containing heavy metal ions, etc.

The design is a frame of two polyprofilen canvases containing sodium bentonite granules and stitched with needle-punched method. The dimensions of the mats are 5.0 × 40.0 m, the thickness is 5.6 or 6.4 mm. The weight of one mat is 950-1300 kg (PSM-Dnepr LLC Ukraine, 03151, Kiev).

Spent sorbent (for example, fly ash), impregnated, for example, with oil, is removed from the cassette and used in road construction as one of the components of the asphalt mix for coating roads.

In order to maintain the level before the curtain groundwater _head H at a depth of 1.0-1.5 m, thereby creating conditions for waterlogging and salinization required adjust the flow rate Q through _{the window} contaminated flow window, selecting window sizes.

The parameters of the filter windows depending on the options are calculated by the following formulas.

For a variant of the air curtain of FIG. 1a, the consumption of contaminated soil flow through a filter window with SF material is determined by the Darcy formula:

where K _FSM is the filtration coefficient of the SF material of the window filler material;

J is the pressure gradient during filtration through the filter window;

a - window height, m;

in - the width of the windows, m;

Δt is the thickness of the curtain, m

The flow rate of the contaminated filtration flow of FIG. 1b through the filter windows in the air curtain is determined by the Dupuis formula:

where h ₁ - UGV in front of the air curtain;

h ₂ - GWP behind the curtain.

The flow rate of contaminated soil flow through the filter windows in the impermeable zone of the air curtain for figv is determined similarly by the formula (1).

The flow rate of contaminated soil flow through the filter windows in the air curtain for Fig.1g is determined by the formula

The flow rate of contaminated soil flow through the filter windows in the air curtain for fig.1d is determined similarly by the formula (1).

The advantage of the proposed method over the known ones is that the proposed method for creating anti-filter curtains with filter windows is more effective than the known ones, it allows you to intercept the contaminated soil stream, clean it of harmful impurities, clarify and deactivate the water without creating water backwash before the anti-filter curtain , and also to reduce the pressure gradient on the PFZ, preventing the destruction of the material of the body of the trench veil.

Claims (2)

1. A method of creating impervious curtains with filter windows, including the development and filling of the trench with a hardening antifiltration material, characterized in that inserts, for example of wood, metal, plastic, are inserted into the developed trench before it is filled with a hardening antifiltration material, and after the antifiltration material has hardened, the inserts are removed and the resulting windows are filled with sorbent-filtering or deactivating-filtering material. 2. The method according to claim 1, characterized in that the windows are filled with a sorbent-filtering or deactivating-filtering material by embedding removable cartridges in the form of a box-shaped frame covered with a mesh cloth and filled with a sorbing-filtering or deactivating-filtering material.

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