Wind-resistant environmental synthetic cover

Abstract

A system for covering (i.e., closing) various types of sites where waste is deposited comprises a composite of one or more geotextiles that are tufted with synthetic yarns and an impermeable geomembrane, which is comprised of a polymeric material. The cover can include wind-resistant textured synthetic blade-like elements, such as vertical filaments, secured over a low-permeable polymer liner backing. Advantageously, the system does not rely on piled-on weight to resist wind forces and the cover can be deployed over a large area with little or no ballasting or anchoring. Optionally, the cover includes vertical filaments attached to the liner to break the wind aero-dynamics on the exposed cover.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims the priority benefit of U.S. Provisional Patent Application Ser. No. 61 / 382,322, filed Sep. 13, 2010, which is hereby incorporated herein by reference.BACKGROUND[0002]Environmental covers (or caps) are used to covers landfills, mines, stockpiles and other waste materials to minimize rain infiltration that can contaminate the groundwater table below. These covers often use synthetic liner materials that are typically covered with two feet of soil that can support natural vegetation. Some of these environmental caps are described in the United States Environmental Protection Agency (40 CFR Sub. D) environmental regulations.[0003]The prescribed covers required by the United States Environmental Protection Agency typically use a two foot soil layer to cover the impermeable geosynthetic layers below. This soil layer can erode easily under major storm events and can be very difficult to maintain, particularly on the steep...

AI Technical Summary

Benefits of technology

[0009]In one preferred form the present invention comprises a wind-resistant cover, including textured synthetic slender elongate elements, such as vertical filaments, secured over a low-permeable polymer liner backing. Advantageously, the system does not rely on piled-on weight to resist wind forces and optionally the cover of the present invention can be deployed over a large area with little or no ballasting or anchoring. This new cover breaks up the airflow over the cover, providing wind uplift resistance.

[0010]Optionally, the cover includes vertical filaments attached to the liner to break the wind aero-dynamics on the exposed cover. With this system, it is believed that the wind velocity on the impermeable surface (membrane) now becomes turbulent near the surface of the cover, thus greatly reducing the actual wind velocity at the liner surface and decreasing associated uplift.

[0012]Advantageously, the wind-resistant cover in this invention can create a larger distance from the material surface to the “free stream” (free stream occurs where the wind flow is unaffected by the material). The cover breaks up the flow stream, increasing the boundary layer (distance from surface to free stream) to the point where uplift forces are very small. This is in stark contrast to a prior art cover with an exposed membrane, where there is a minuscule distance to the uninterrupted free-stream air flow. This small boundary means that there is a large velocity differential over a very short distance creating much higher uplift.

[0014]The synthetic cover portion of this environmental closure also acts as a protective layer providing protection from physical damage and weathering to the geomembrane liner below. Thus, the present invention can extend the longevity of the geomembrane component over a much longer period of time in comparison with the conventional exposed geomembrane covers.

[0015]This invention, in a preferred form, uses a lower geomembrane with roughened or structural components to increase the friction resistance against the lower soil and interface friction between the cover and the geomembrane. Preferably, the angle of friction can be higher than 18 degrees.

Problems solved by technology

This soil layer can erode easily under major storm events and can be very difficult to maintain, particularly on the steep slopes of landfills and mine stockpiles.

However this type of exposed geosynthetic cover requires extensive anchoring and or ballasting to protect the cover against wind uplift in the presence of strong winds.

The anchoring system can be very extensive resulting in large construction costs.

The exposed geosynthetic liner material also weathers more rapidly as a result of lack of a protective cover.

However, such covers with an exposed membrane generally have negative aesthetics and require extensive anchoring or ballasting.

The prior art ballasting techniques are expensive, often impractical and their effectiveness is typically limited to winds below about 40 mph.

Additionally, this type of cover only last a few years due to damage from wind.

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