GB1602400A

GB1602400A - Storage reservoir

Info

Publication number: GB1602400A
Application number: GB2226378A
Authority: GB
Original assignee: Sumitomo Electric Industries Ltd
Current assignee: Sumitomo Electric Industries Ltd
Priority date: 1977-06-22
Filing date: 1978-05-25
Publication date: 1981-11-11

Description

(54) A STORAGE RESERVOIR (71) We, SUMITOMO ELECTRIC INDUS TRIES LIMITED, a Japanese Company, of No.

15, Kitahama 5-chome, Higashi-ku, Osakashi, Osaka, Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a storage reservoir utilizing a flexible sheet, and more particularly to a reservoir employing a flexible sheet laid over the surface of place of excavated or depressed ground.

Reservoirs in which a flexible sheet made of such as rubber, rubber-coated cloth, or vinyl chloride is laid over the surface of an excavated or depressed piece of ground, have recently found a wide application in many fields of industry, for instance, a large scale reservoir as a water source, a waste water treating pond and the like.

The reservoirs utilizing flexible sheets, particularly those which utilize sheets made of rubber or rubber-coated sheets provide the following advantages: (1) low expense: (2) simple installation procedure: (3) short construction period: (4) negligible amount of water penetrating through a flexible sheet: and (5) long service life or durability.

However, the most cumbersome shortcoming or problem encountered with the manufactures of the sheets of this kind is grass, miscanthus, or bladygrasses which tend to pierce through the sheet, after its installation with the result of the leakage of water stored in a reservoir, into the ground beneath the sheet.

To cope with this, it has been a general practice to spray a weeding agent or solution over the ground before laying a sheet in position. However, this attempt has met with only partial success, still leaving a stubborn, plant root piercing problem such as caused by grass, mescathus and bladygrasses.

Various tests have been made in an attempt to overcome the aforenoted shortcomings in the conventional construction of storage reservoirs, particularly in a place where many kinds of grass or plants are likely to grow and one object of the invention is to provide a storage reservoir which at least partly overcome the problem referred to.

According to one aspect of the invention, a storage reservoir comprises a piece of excavated ground having one or more upwardly sloping side wall portions, a flexible sheet of liquid impervious material over said excavated ground, an outermost end portion of said sheet being embedded into soil of said ground to prevent it from slipping down onto said side wall portion or portions, and a plant root piercing preventive layer disposed between said flexible sheet and said excavated ground.

The test results reveal that the grass or miscanthus or bladygrasses at places at a depth exceeding one meter from the water level are not likely to pierce through the sheet. The reason for this may be a decrease in amount of oxygen to be supplied and water pressure.

Thus in a further, preferred form of this aspect of the present invention, said outermost end portion of said flexible sheet is reinforced with a plant root piercing preventive layer, so as to prevent the piercing of buds or roots of plants through the sheet.

In a further aspect of the invention there is provided a method of producing a storage reservoir comprising providing a piece of excavated ground having one or more upwardly sloping side wall portions, laying a flexible sheet of liquid impervious material over said excavated ground with a plant root piercing preventive layer disposed between said flexible sheet and said excavated ground, and embedding an outermost end portion of said sheet into soil of said ground to prevent it from slipping down onto said side wall portion or portions.

The invention will now be described by way of example with reference to the accompanying drawings, in which: Fig. 1 is a top view of a storage reservoir constructed according to the invention; Fig. 2 is a cross-sectional view taken along the line IIII of Fig. 1; Fig. 3 is a cross-sectional view illustrative of one example of a storage reservoir according to the invention, in which a flexible sheet and a plant root piercing preventive layer bonded thereto are laid over excavated ground; Fig. 4 is a cross-sectional view of another example of a storage reservoir according to the invention, in which a flexible sheet and a plant root piercing preventive layer separate therefrom are laid over said excavated ground.

Fig. 5 is a transverse cross-sectional view of a storage reservoir constructed according to another embodiment of the present invention, showing an outermost end portion of the flexible sheet coated with the plant root piercing preventive layer and vertically embedded into soil; and Fig. 6 is an enlarged view of the part marked by a circle in Fig. 5.

As shown in Figs. 1 and 2, a storage reservoir is formed by providing an excavated piece of ground 1, having a bottom portion with sloping sides extending upwardly therefrom, and laying over the surface thereof a rubber sheet or rubber-coated sheet 2 of a thickness of, for example, 1.5mum.

Sandbags 3 are placed on the four corners of the sheet 2 to prevent the displacement of the sheet 2 during a dry season of the year. The sandbags 3 are prepared by filling polypropylene bags with gravel of diameter of 30 to 50mm. The outermost end portion of the sheet is, as shown in Figure 2, embedded into soil of said ground, to prevent it slipping down the sloping sides of the excavated ground.

Shown at 4 is a water supply pipe line, at 5 a water-discharge pipe line, at 6 soil, and at 7 channels into which said end portion of the sheet is embedded.

In the reservoir of the type thus described, according to the present invention, a plant root piercing preventive layer 10 is provided between the sheet 2 and the ground, wherein the layer 10 is provided to cover the entire bottom surface of the sheet 2. Alternatively the layer 10 is locally provided, below the sheet 2, for example, the portions which has the water level less than lm, thereby to prevent any plants from piercing through the sheet 2.

Included by the aforenoted layers 10 which may be employed according to the present invention are those made of a metal foil of such as aluminium, or flexible materials such as polyethylene, vinyl chloride, polypropylene, nylon polyester, rubber and the like. As an alternative, a laminated layer consisting of fibres such as nylon fibres and the above flexible materials may be used.

The advantages or effects to prevent the piercing of plants by means of flexible materials made of such as polyethylene, vinyl chloride, polypropylene, nylon, polyester and the like, have been confirmed by the tests among various plastics materials.

As shown in Fig. 3, the plant root piercing preventive layer 10 may be bonded to the sheet 2, as shown by an arrow mark, before the installation thereof. Alternatively, as shown in Fig. 4 the preventive layer 10 may be laid over a given place in an excavated piece of ground 1, and thereafter the sheet 2 laid on top of the layer 10, as shown by an arrow mark. However, the former is recommendable from view point of ease of operation. The outermost end portion of the storage reservoir is positioned in the channel 7 to embed the end portion into the soil 6.

A metal sheet such as an iron sheet or aluminium sheet, or a cement layer may be used for the plant root piercing preventive layer 10. In this case, the metal sheet is previously shaped to desired surfaces of an excavated ground. However, this attempt results in an increased cost to instal the same.

Referring to Figs. 5 and 6, the outermost end portion 11 of the sheet 2 is embedded into the soil 6 to prevent the sheet 2 from slipping down onto the slanting wall portion of the excavated ground, the end portion in this example being vertically embedded. The end portion 11 is provided with a plant root piercing preventive layer 10' at the outer periphery thereof so as to prevent roots of the plants from piercing therethrough.

The depth of the layer 10' is greater than the maximum depth of the roots of plants, namely, the depth of the layer 10' is generally on the order of 30 to 50 cm. In addition, the layer 10' may be made of such as rubber, plastics material, a material made of rubber and/or plastics material fibres, a metal member such as made of aluminium foil, aluminium sheet, concrete or the like.

The lowest end of the embedded portion 11 is not necessarily coincident with the lowest end of the preventive layer 10'.

In addition, the end portion of the sheet may be formed integrally with the plant root piercing preventive layer 10' before hand, or the layer placed in an excavated ground separately and then the sheet laminated integrally on top of the former.

WHAT WE CLAIM IS 1. A storage reservoir comprising a piece of excavated ground having one or more upwardly sloping side wall portions, a flexible sheet of liquid impervious material over

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. side wall portion or portions. The invention will now be described by way of example with reference to the accompanying drawings, in which: Fig. 1 is a top view of a storage reservoir constructed according to the invention; Fig. 2 is a cross-sectional view taken along the line IIII of Fig. 1; Fig. 3 is a cross-sectional view illustrative of one example of a storage reservoir according to the invention, in which a flexible sheet and a plant root piercing preventive layer bonded thereto are laid over excavated ground; Fig. 4 is a cross-sectional view of another example of a storage reservoir according to the invention, in which a flexible sheet and a plant root piercing preventive layer separate therefrom are laid over said excavated ground. Fig. 5 is a transverse cross-sectional view of a storage reservoir constructed according to another embodiment of the present invention, showing an outermost end portion of the flexible sheet coated with the plant root piercing preventive layer and vertically embedded into soil; and Fig. 6 is an enlarged view of the part marked by a circle in Fig. 5. As shown in Figs. 1 and 2, a storage reservoir is formed by providing an excavated piece of ground 1, having a bottom portion with sloping sides extending upwardly therefrom, and laying over the surface thereof a rubber sheet or rubber-coated sheet 2 of a thickness of, for example, 1.5mum. Sandbags 3 are placed on the four corners of the sheet 2 to prevent the displacement of the sheet 2 during a dry season of the year. The sandbags 3 are prepared by filling polypropylene bags with gravel of diameter of 30 to 50mm. The outermost end portion of the sheet is, as shown in Figure 2, embedded into soil of said ground, to prevent it slipping down the sloping sides of the excavated ground. Shown at 4 is a water supply pipe line, at 5 a water-discharge pipe line, at 6 soil, and at 7 channels into which said end portion of the sheet is embedded. In the reservoir of the type thus described, according to the present invention, a plant root piercing preventive layer 10 is provided between the sheet 2 and the ground, wherein the layer 10 is provided to cover the entire bottom surface of the sheet 2. Alternatively the layer 10 is locally provided, below the sheet 2, for example, the portions which has the water level less than lm, thereby to prevent any plants from piercing through the sheet 2. Included by the aforenoted layers 10 which may be employed according to the present invention are those made of a metal foil of such as aluminium, or flexible materials such as polyethylene, vinyl chloride, polypropylene, nylon polyester, rubber and the like. As an alternative, a laminated layer consisting of fibres such as nylon fibres and the above flexible materials may be used. The advantages or effects to prevent the piercing of plants by means of flexible materials made of such as polyethylene, vinyl chloride, polypropylene, nylon, polyester and the like, have been confirmed by the tests among various plastics materials. As shown in Fig. 3, the plant root piercing preventive layer 10 may be bonded to the sheet 2, as shown by an arrow mark, before the installation thereof. Alternatively, as shown in Fig. 4 the preventive layer 10 may be laid over a given place in an excavated piece of ground 1, and thereafter the sheet 2 laid on top of the layer 10, as shown by an arrow mark. However, the former is recommendable from view point of ease of operation. The outermost end portion of the storage reservoir is positioned in the channel 7 to embed the end portion into the soil 6. A metal sheet such as an iron sheet or aluminium sheet, or a cement layer may be used for the plant root piercing preventive layer 10. In this case, the metal sheet is previously shaped to desired surfaces of an excavated ground. However, this attempt results in an increased cost to instal the same. Referring to Figs. 5 and 6, the outermost end portion 11 of the sheet 2 is embedded into the soil 6 to prevent the sheet 2 from slipping down onto the slanting wall portion of the excavated ground, the end portion in this example being vertically embedded. The end portion 11 is provided with a plant root piercing preventive layer 10' at the outer periphery thereof so as to prevent roots of the plants from piercing therethrough. The depth of the layer 10' is greater than the maximum depth of the roots of plants, namely, the depth of the layer 10' is generally on the order of 30 to 50 cm. In addition, the layer 10' may be made of such as rubber, plastics material, a material made of rubber and/or plastics material fibres, a metal member such as made of aluminium foil, aluminium sheet, concrete or the like. The lowest end of the embedded portion 11 is not necessarily coincident with the lowest end of the preventive layer 10'. In addition, the end portion of the sheet may be formed integrally with the plant root piercing preventive layer 10' before hand, or the layer placed in an excavated ground separately and then the sheet laminated integrally on top of the former. WHAT WE CLAIM IS

1. A storage reservoir comprising a piece of excavated ground having one or more upwardly sloping side wall portions, a flexible sheet of liquid impervious material over

said excavated ground, an outermost end portion of said sheet being embedded into soil of said ground to prevent it from slipping down onto said side wall portion or portions, and a plant root piercing preventive layer disposed between said flexible sheet and said excavated ground.

2. A storage reservoir as claimed in claim 1, wherein said plant root piercing preventive layer is integrally formed with said flexible sheet.

3. A storage reservoir as claimed in claim 1, wherein said plant root piercing preventive layer is formed separately from said flexible sheet.

4. A storage reservoir as claimed in claim 2 or claim 3, wherein said plant root piercing preventive layer is made of a metal foil.

5. A storage reservoir as claimed in claim 2 or claim 3, wherein said plant root piercing preventive layer is made of rubber, plastics material or a composite material consisting of rubber or plastics material and fibres.

6. A storage reservoir as claimed in claim 2 or claim 3, wherein said plant root piercing preventive layer is made of plastics material or a sheet consisting of plastics material and fibres.

7. A storage reservoir as claimed in claim 3, wherein said plant root piercing preventing layer is made of cement.

8. A storage reservoir as claimed in any one of the preceding claims, wherein said flexible sheet is made of rubber or is a rubber coated sheet.

9. A storage reservoir as claimed in any one of claims 1 to 9, wherein said outermost end portion of said flexible sheet is formed with a plant root piercing preventive layer.

10. A storage reservoir as claimed in claim 9, wherein said plant root piercing preventive layer embedded in said soil is positioned at a depth exceeding the maximum depth of roots of plants, at which said roots are likely to damage said flexible sheet.

11. A storage reservoir as claimed in claim 9, wherein said plant root piercing preventive layer embedded in said soil is positioned at a depth exceeding 30 cm from the top surface of said soil.

12. A storage reservoir as claimed in any of claims 9 to 11, wherein said plant root piercing preventive layer is made of concrete material.

13. A method of producing a storage reservoir comprising providing a piece of excavated ground having one or more upwardly sloping side wall portions, laying a flexible sheet of liquid impervious material over said excavated ground with a plant root piercing preventive layer disposed between said flexible sheet and said excavated ground, and embedding an outermost end portion of said sheet into soil of said ground to prevent it from slipping down onto said side wall portion or portions.

14. A method as claimed in claim 13, wherein said outermost end portion of said flexible sheet is formed with a plant root piercing preventive layer.

15. A method as claimed in claim 14, wherein said plant root piercing preventive layer embedded in said soil is positioned at a depth exceeding the maximum depth of roots of plants, at which said roots are likely to damage said flexible sheet.

16. A method as claimed in claim 13, wherein said plant root piercing preventive layer embedded in said soil is positioned at a depth exceeding 30cm from the top surface of said soil.

17. A storage reservoir substantially as hereinbefore described with reference to and as shown in Figures 1 and 2, or Figure 3 or Figure 4 or Figures 5 and 6 of the accompanying drawings.

18. A method of producing a storage reservoir substantially as hereinbefore described with reference to and as shown in Figures 1 and 2, or Figure 3 or Figure 4 or Figures 5 and 6 of the accompanying drawings.