DE4000315A1 - Controlled drainage of refuse dumps- involves using sheet of sealing material which is covered with layers of coarse and fine sand - has low sensitivity to external mechanical influences and has suspended sensor or transducer - Google Patents

Abstract

The method is for controlling the drainage of water from underneath a refuse dump. The site of the refuse dump is prepared by first laying down a sheet of sealing material (7). This sealing material is covered with a layer of coarse sand (1) which is in turn covered with a layer of fine sand (2). There is a clearly defined difference in size between the coarse grains in the bottom layer (1) and the fine grains in the top layer (2). The layer of fine sand (2) is covered with a second layer (6) of sealing material. In the event of damage to the upper sealing layer, water which penetrates the layer of fine sand is constrained to flow between the fine and coarse layers due to the capillary effect of fine sand. This interflow flows into the drainpipe (5). USE - Controlled drainage of refuse dumps.

Description

The invention "Device and method for control and additional sealing of landfill base seals "concerns a drainage layer to control the landfill base seals.

The invention is based on the following literature:

To the capillary barrier:

Melchior, S. & Miehlich, G. 1988:
Large-Scale Lysimeters Studies on the water balance of Multilayered covering systems on the waste disposal site Georgswerder (Hamburg) in Proceedings of the Unesco Workshop on Impact of waste disposal on ground water and surface water, Copenhagen.

For basic seals (landfill sites)

Laga leaflet (1979)
The orderly disposal of waste. In: Garbage Handbook, reference number 4690, Erich Schmidt Verlag.
Steffen, H. (1986):
Basic seals for landfills. In: Garbage manual, code 4543, Erich Schmidt Verlag.
Hessian State Institute for the Environment, HLfU (1986):
Requirements criteria for the landfill contact area and the mineral sealing system.

Recommendations of the Working Group on Geotechnical Engineering at Landfills and Contaminated sites of the Deutsche Gesellschaft für Erd- und Grundbau e. V. Special print from: Bautechnik, 64 (1987), H. 9, pp. 289-303. publishing company Wilh. Ernst & Son.

For basic seals (hazardous waste landfills)

Rückel, HG (1989):
The Raindorf hazardous waste landfill. In: Garbage manual, reference number 8186, Erich Schmidt publishers.

Voller, M. & Mehlhorn, B. (1987):
Special waste landfill Hoheneggelsen. In: Garbage manual, code 8185, Erich Schmidt Verlag.

Dewey, WJ (1989)
Storage of commercial waste for days. In: Garbage manual, code 8187, Erich Schmidt Verlag.

The given structure should be controllable from Landfill base seals and location of leaks as well as at Failure of the sealing system a hydraulic renovation enable outside of groundwater levels. As another The property is the additional sealing effect and protection the lower sealing unit.

According to the state of the art, the basis of household waste and Special waste landfills to be provided with a combination seal. A mineral seal is placed on a subsurface applied, on which a plastic film, usually HDPE with a thickness of 2 mm. The pent-up Landfill leachate is fed through surface filters and Leachate drainage pipes of a landfill's own landfill fed water purification system.

With this arrangement it is not guaranteed that at one possible damage to the base seal no contaminated Water get into deeper layers. Even one Control drainage, built up from a grain of one Grain size class does not have the functions of sealing effect and Protection of the lower sealing system.

The invention has for its object the underground of To protect landfills from contamination to an even greater extent, than previously required by law. This is through the Characteristic features of the claim met and goes far beyond the state of the art.  

The object is achieved in that a control drainage is installed between two sealing units ( 6, 7 ) or under any type of basic seal. This is constructed as a capillary barrier made of fine sand ( 2 ) with a subordinate capillary block ( 1 ) made of coarse sand, with a significant grain size jump to the capillary barrier. If there is damage in the upper sealing unit ( 3 ), the capillary barrier is soaked up with leachate. Menisci form at the capillary barrier / capillary block boundary due to capillary forces. These require an intermediate outflow (Interflow, 4 ) of the leachate to the control drainage pipes ( 5 ) which are laid at regular intervals. Only when the hydraulic rise of the accumulated leachate exceeds the capillary forces can leachate reach the capillary block to a greater extent. However, only the sealing effect and the protection of the lower seal against aggressive leachate are lost, the control and remedial function are retained (see below).

The special advantages of this inexpensive construction are that basic seals can be checked without much effort and possible leakage areas using monitors in the Control drainage pipes can be located quickly. A leachate build-up on the base seal with associated stress the same is due to interflow effects at the border Fine sand / coarse sand avoided.  

Due to these effects the control layer has additional ones Sealing properties. Furthermore, the control drainage Pipes can be used as renovation pipes in the event of damage.

An example of the structure of the invention is in the drawing shown. The numbers mean:

1 capillary block (coarse sand)
2 capillary barrier (fine sand)
3 seal damage (exemplary)
4 Interflow as a hydraulic lock
5 control drainage pipe
6 Upper seal (exemplary)
7 lower seal (exemplary)

Claims (1)

Control drainage for checking landfill base seals. The Control drainage is characterized by the structure as Capillary block with assigned control drainage or Renovation pipes.