Geomembrane Linings

GEOMEMBRANE LININGS – are continuous flexible sheets manufactured in roll form from one or more polymeric base materials. They are relatively impermeable and are used as liners for fluid or gas containment and as vapour barriers.

PARKSIDE-BSS has strategically aligned itself in a business development sense with “Rowad” a major leading global manufacturer of HDPE (high density polyethylene), LLDPE (linear low density polyethylene).

Geomembrane liners are produced utilising state-of-the-art blown film and flat die extrusion processes manufactured using a continuous multi-layer, co-extrusion process using high quality proprietary and virgin polyethylene resins.

The important properties of High Density Polyethylene (HDPE) and Linear Low Density Polyethylene (LLDPE) include:

An overview of the product range

The basic products are black/black, but other variants are available for more specific and technically challenging applications.

The white/black version is used for improved quality control management on-site and reduction of heat generated at the surface of the product, thereby reducing the tendency to generate wrinkles and undulations which occur naturally as a result of expansion and contraction movements. This provides a lining system which is in more intimate contact with the installed layers directly above and below.

Thicknesses range from 0.5mm – 3.0mm. and supplied in 8.0m metre roll widths (Some of the widest width available globally) reduce installation time and costs as well as minimizing the potential for any leakage effects by reducing the quantity of on-site welding required to complete the work.

WELD ROD is available in 4mm and 5mm diameters and is fully compatible with the parent sheets.

Smooth, Textured and Enhanced Textured (ETEX) and coloured liners are produced by blown film and flat die manufacturing methods to provide increased friction angles for interface stability on steeper slope applications and reduces the potential for slippage between adjacent layers.

Whilst the basic properties of all products comply with GM13 and GM17 International standards, Project-specific parameters can be achieved with modified recipes in many instances, depending on requirements and quantities.

PARKSIDE-BSS and its strategic manufacturing partners work very closely with all of their clients to ensure that their expectations on product type, quality, project specific standards and service levels are all met. This is achieved through rigorous strict quality and process control in all aspects of our supply, manufacturing and stock systems.

Rigorous Quality Management Programs ensures that products are consistently of the highest and correct quality, whilst Operational Excellence Programs which have been implemented ensure efficiencies are of the highest level in all aspects of the production cycle.

Certifications, Approvals and Memberships

Main Application Areas

The Following section provides an overview of the main application areas for Geomembrane linings. The overview which is presented is by no means exhaustive and we would invite you to contact us for any discussions on any specific product application which is not covered here.

MINING

Heap Leach Pads

The Heap-leach process is now a globally accepted means of large –scale surface mining and extraction employing the use of chemical reagents to percolate through stacks or heaps of generally low grade crushed oxide mineral deposits in the generation of highly charged chemical solutions which are further processed in the winning of valuable non-ferrous metals on a large commercial scale and which generally include Gold, Copper, Nickel.

The techniques employed in Heap leaching require an approach to mineral extraction which constitutes a fine balance between commercial and environmental expedients. The client requires the maximum extraction efficiencies at minimal cost and with minimal loss of product whilst the Environmental Councils insist that there should be minimal negative impact on the local Environment.

The use of flexible Geomembrane liners in this process is crucial in that the liner should be resistant to the chemically charged solutions passing over and stored within them, whilst the installation techniques should ensure that the liner system remains intact and does not allow the leakage or loss or valuable product.

The liner system occupies a position at the base of each Heap Pad or stack and collects and diverts product in solution away from the pad into solution trenches down to a series of ponds or lagoons where pregnant solution is stored and further processed.

TAILINGS STORAGE TSF

In comparison to the heap leach process, these Tailings and slimes Dams are large scale waste deposits from the mining or process industries which contain very fine, silt grade fractions of product which are transported by pipelines to the waste dam or dump and then discharged in hydraulic form over the floor and walls of the dam in a series of walls and beaches consolidating before the next phase of discharge is made.

These dams and dumps are typical of waste areas adjacent to Fertilizer process Industries, Coal Mines, Iron & Steel works, Gold, Copper and Nickel refineries and concentration plants.

Due to the highly liquid state of waste product which is supplied to the dams, a period of consolidation under its own weight is allowed to occur where the product effectively de-waters. The supernatant or overflow is then allowed to pass via a series of vertical penstocks in the dams which is then fed below the base of the Dams to residual storage lagoons where further storage and evaporation takes place.

Because the Heap leach process uses mechanical placement of ore whilst the Slimes and Tailings facilities use hydraulic techniques for finer fractions, then the liner selection is of generally thicker grades of HDPE for Heap leach whilst the Slimes dams generally employ thinner to medium grades of liner.

In both cases, the liner design, selection and installation should ensure long term durability and chemical resistance with weld integrity over the operational life of the structure.

SOLUTION PONDS / CHANNELS

The liner systems used in these facilities are often more critical in terms of their aspects of design selection and installation than the adjacent waste or heap depositories which they serve. This is mainly due to the fact that there is a much greater hydraulic head of highly chemically – charged solutions exerted upon the liner system than there is in waste dams or heap leach which are equipped with basal drainage layers for unimpeded evacuation of liquids.

To cope with this additional need for security against potential leakage, the liner system is often designed with thicker membranes and can comprise multiple layers with intermediate drainage layers for the purpose of detecting and collecting any leakage which results from defects in the Primary (Upper) liner component, sometimes equipped with additional inspection tubes and pumps for the further recovery of product.

Landfill – basal linings and cap closures

The Geomembrane liner in basal applications should be the most effective line of defence in protecting the environment and is generally the lowest cost component of the total cost of a project.

Geomembrane linings often form one essential component of a lining system in what is a natural bioreactor and prevents potentially harmful leachate which is produced by decomposing organic compounds. Such linings should be extremely durable and resistant to the components of these organic liquids over many decades and often centuries.

At the end of life of landfills, the site is capped with a suitable liner and used in the closure and rehabilitation of these sites. A development which is receiving increasing use is the incorporation of a gas collection and removal system below and through the cap to draw gas into turbines for the generation of electricity.

LINED BUNDS for the PETRO-CHEMICAL INDUSTRY

Tank storage facilities for the petro-chemical industry can be large in terms of volumes of product stored and are designed with surrounding security bunds to contain any catastrophic spillage which might occur. These bunds are designed with a factor of safety so that overtopping is not possible in the event of major tank failure events.

The products stored are generally liquid gas, petroleum, crude oil and other potentially hazardous chemicals and products. It is therefore imperative that when used for the storage of such products these tanks and systems remain intact for the life of service.

However, instances have been recorded whereby the steel is subject to corrosive effects approximately 1 -2m up from the base as a result of attack by galvanic action, whilst concrete structures can be prone to attack by lime hungry chemicals and both are susceptible to movements as a result of ground movements which can affect their stability and integrity.

When such corrosive effects or movements are extreme the inevitable consequence is for product to spill and can have a pronounced effect on the local environment, with severe consequences for general health and public safety.

In recent times, legislation has required the use of liner systems to be applied to the areas immediately below the tank bases and also throughout the entire security bund area. These liner systems can be installed during the construction cycle of new tanks, installed in the foundation zone or can be retro-fitted to these zones as a means of upgrading security in older tanks.

Whilst most liner systems are not acceptable for use as primary liners in direct contact with the hydro-carbon rich liquids, they represent the best solution for emergency capture of spillage and for the protection of the environment as secondary liners in that they prevent direct contact of product with the local environment and allow sufficient time for the removal of spilled product from the area in the aftermath of failure.

Farm Lagoons and Irrigation Dams

Flexible Geomembrane lining systems constitute what is now fast becoming the first choice for clients in the Agriculture and Horticultural industries, who require a quick, cost –effective means of storing their liquids in earth dams, lagoons and ponds in the immediate and long term.

Flexible Geomembrane linings which are non toxic, chemically inert and durable are imperative for the containment, mainly of water for irrigation of food crops and flowers, particularly in the dry seasons when drought and water shortages can have devastating effects on the quality and condition of the crop with potential loss of revenue for the farmers.

Such linings are generally of thin to medium grade, can be quickly installed by experienced contractors and provide an immediate solution to storage problems.

Evaporation and retention ponds

The liner systems used in these facilities are often more critical in terms of aspects of design selection and installation. This is mainly due to a much greater hydraulic head of chemically-charged solutions exerted upon the liner system.

To cope with this additional need for security against potential leakage, the liner system is often designed with thicker membranes and can comprise multiple layers with intermediate drainage layers for the purpose of detecting and collecting any leakage.

A growing and important application is the use of linings over permeable soils in the production of commercial salt projects where the linings allow retention of brine within a series of shallow evaporation ponds leading via decanting structures to the final harvesting areas. Here, salt of a specific purity can be produced and extracted before being processed in the nearby plant for washing, crushing, grading packing and dispatch to market.

Potable water reservoirs – Basal linings and Floating covers

The storage and supply of drinking water has become a crucial part of supporting the development and growth of populations in existing and new geographic areas.

Traditionally, concrete has been used to store water, but with the advent of Geomembrane linings, a quicker and more cost effective means for construction and operation has been achieved. The Geomembrane not only store water in the conventional way but overcome the need for extensive and ongoing maintenance of concrete joints and cracks over time. The roof is constructed in the form of a floating Geomembrane cover which can be adapted to any size and shape of reservoir and lies on the water surface floating up and down as the water level fluctuates.

This assists in maintaining water quality at the desired levels by preventing dust and debris from entering the stored water body and overcomes issues of evaporation loss in hot equatorial zones as well as odor control from industrial sites which may be in close proximity to residential areas.

Tunnels

The excavation of tunnels is usually undertaken to run a service more easily through a range of hills or mountains.

Such services usually take the form of road or rail transport routes or can take the form of water transfer schemes passing millions of litres of water per day. Geomembrane liners form an integral part of the tunnel liner system, resisting a wide range of acidic and alkali water types and preventing the ingress of ground water.

SPORT, LEISURE & BUSINESS

Liners to Golf Course, Business Park, Sport Grounds Decorative Ponds and Lakes

The constant splashing and movement of water in a feature is a pleasure for everyone to enjoy and a well constructed decorative pond will give a lifetime of pleasure.

A pond that leaks, however, is a constant source of irritation to the client, both in time and effort spent in attempts at repairs and also in the actual cost of time and materials.

Oftentimes, the sites which are selected for the location of a water feature do not possess impermeable clay strata, so water-tight features incorporating liners are essential.

Concrete, shotcrete or fibreglass liners often crack with time as poorly compacted soil settles and creates cracks in what are regarded as more brittle liner types. What frequently occurs is the formation of cracks and fissures below the water line and below cascades and overhangs where their identification is not easy, resulting in constant needs for top-up with water, representing inconvenience and cost.

Geomembrane liner products which have been used in major and critical industrial water storage projects for the last 4 decades have now been adapted for use in landscaping and aesthetic water designs, where qualities which have ensured their success in more demanding construction activities now present excellent solutions for more decorative water storage purposes.

Smooth, flexible medium grade Geomembranes are the preferred choice due to the fact that they do not allow the attachment of micro-organisms, they do not damage fish fins and tails, are easily cleaned and maintained and improve overall pump efficiencies. They also can be applied to more irregular and odd shapes more easily than rigid materials due to their ability to be “tailored” to suit specific shapes and sizes.

HDPE ,LLDPE and fPP are material types which are well suited to the construction of decorative ponds and have been the materials of choice for many large corporate ponds, some of great complexity.

In all respects, the liner design, selection and installation should ensure long term durability and chemical resistance with weld integrity over the operational life of the structure and this should be undertaken by experienced contractors. PARKSIDE-BSS is also well placed to advise on suitable contractors where required.

Attachment of liner system to inlet, outlet and over structures and to fountain stems and other protruding structures are all-important aspects of the liner design and installation.

Whilst flexible liner systems are designed to operate without any cover or protective material, the appearance and protection of liner systems can be greatly enhanced with the use of protective geotextiles, stone pitching, Soil containment cells and much more.

FOR MORE INFORMATION ON GEOMEMBRANE LININGS : we would invite you to contact us for discussions on any specific product application which is not covered above and we would be pleased to assist.