Ponds need Pond Liners like a building needs a foundation. Among all the materials used for Pond Liners, plastic is the most versatile. It comes in two forms- pre-formed and flexible.
Preformed or rigid plastic liners are strong and long-lasting. They are made of polythene and other recycled plastic material. They do not develop leaks. They are more cost-effective than concrete. An average gardener can set up a small pond within one day using this liner.
Some of these models are fitted above the ground and some below the ground. Rocks and stones may be placed around it to give a natural look. The liners may be both UV- as well as frost-resistant. But they may be difficult to fit because of their different shapes and sizes.
Among the preformed models, the plastic liners may be cheaper than fiberglass, but do not offer support for free-standing use of the pond in a raised water garden. It is difficult to build around a plastic pond and support it evenly. When support is not uniform there is a danger that the plastic liner will crack.
Flexible Pond Liners are also available, like PVC (Poly Vinyl Chloride) and HDPE (High Density Poly Ethylene).These liners are not as flexible as rubber. Plastic liners are often used on large holding ponds when economy is a bigger concern than flexibility.
Large ponds require a Pond Liner that is safe for fish and aquatic plant life, inexpensive, easy to install and durable. Polyethylene fits the bill. Medium-density Polyethylene contains up to 5 percent carbon black, which makes it highly UV stable and suited to outdoor life. Twenty and 30 mm polyethylene can be custom-made according to your specifications.
PVC, or Polyvinyl Chloride, has excellent chemical compatibility and puncture resistance, lending itself to membrane liner applications. Some PVC liners contain UV stabilizers which protect them from breaking down when exposed to sunlight. PVC is not a crystalline membrane liner material, so it can elongate in all directions. It is the most cost-effective buried membrane and it has the longest successful use of liner material.
Another plastic is Polypropylene. It has special properties, like outstanding dimension stability, low coefficient of expansion and contraction, wide temperature seaming range, good chemical resistance and no stress cracking.
Plastic has its plusses and minuses, and the choice depends on the individual's requirements.
Getting goods from A to B is hard enough. Finding the right way to carry those goods is another headache. Once, we loaded and unloaded goods item by item - those were the days when labour was cheap. Then the Second World War came. This mother of many inventions brought us the wooden pallet. This, combined with a fork lift truck, enabled goods to be moved quickly and with less labour.
The wooden pallet was a great idea. So good was the idea that it is still going strong to this day. However, things have changed. Pallet pooling can be an expensive business. Rental and purchase costs have risen to reflect the increase in timber costs and the extra burden of fumigation and quality control.
Escalating fuel costs have taken their toll on the inevitable dedicated trips that are made to repatriate empty pallets when imbalances occur in the supply chain. These fuel costs - and driver shortages - have also forced an examination of the space and weight taken up by the ubiquitous pallet.
The pallet is a bit like the air that we breathe. It is all around us yet we don't see it. It is easy to forget the extra cost that the pallet adds to the value chain. Perhaps now the time has come when, in some eyes, the pallet has outstayed its welcome. Rather than being the carrier, is the pallet itself being carried by the value chain? Rather than wait for another world war, a ready solution has been found and is tried and tested. That is the Slip Sheet.
Enter the Slip Sheet
Slip sheets have been around for some time, especially in the
U.S. where the free market has always had the knack of taking the path of least resistance. European countries tend to prefer centrally planned systems and standardization. Slip sheets lack firmly agreed international standards and this may be one of the reasons why they have not been popular in Europe. The greatest reason is ignorance. Many simply have no understanding of slip sheets and how they work - so they don't bother.
So perhaps it's time to right this wrong here and now.
How Slip Sheets Work
1. Slip sheets are durable sheets of material that are designed to carry a uniform load of goods with plan dimensions (or "footprint") of roughly 1 metre square/40 inches square (typically they may be designed to carry a footprint of 40 inches x 48 inches - 1m x 1.2m). The slip sheet is made to these dimensions plus a pull tab - an extension to the sheet - of up to 6 inches/15cm. There may be just one pull tab sticking out from under the load on one side. There could, however be pull tabs on 2, 3 or all 4 sides. Slip sheets can be made of
fibreboard or plastic.
2. Goods are loaded directly onto the slip sheet within the creases that border any pull tabs. A push-pull attachment on a forklift truck is used to drag the load onto the truck by gripping (one of) the pull tab(s). The push-pull attachment has very flat ground-level forks that are designed to go under the
slip sheet whilst it is under load
3. To unload, the forklift truck pushes the load, complete with slip sheet off of itself and withdraws
Pros and Cons
Slip sheets are not the panacea to all distribution needs. For one thing, all parties in any supply chain will need to invest in the push-pull attachments, which are not cheap. The staff training that will be required, especially for forklift truck operators, can also be expensive. Perhaps the greatest factor, though, is the uniformity of the load itself. This exposes the slip sheet's greatest advantage - and greatest disadvantage. Slip sheets may not be able to cope when boxes are awkwardly shaped or where there is a mixed load of different shapes. Conversely, if a company is shipping out large quantities of the same sized box, then slip sheets are ideal. As such, slip sheets lend themselves to operations further upstream of the supply chain. As loads are broken down further downstream, then pallets may be more appropriate. The good thing is that loads of slip sheets can be easily transferred to pallets. A good example of the advantages of using slip sheets is where parts for goods are manufactured and shipped through a long distance sea route. The space and weight saving can result in a significant financial boost for the value chain.
Co-operative Value Chains
Another great factor in all this is uniformity of slip sheet systems. All parties in the supply chain need to be using the same specification of slip sheet and ensure that all staff are fully trained to ensure delivered loads are configured correctly for the receiving party. This requires value chains that are highly co-operative, or, to be realistic, it requires a value chain that has one dominant party who will simply dictate their requirements. The U.S. has pioneered slip sheets and has used them for many years. However, the dominance of the supermarket sector in some European countries may be forcing the change there also. The ability of large supermarkets to influence their supply chains means that they are in a position to take a strategic view of the benefits that slip sheets can bring. They are in a position to arrange for both senders and receivers to be ready to handle products on slip sheets. Things are changing. Perhaps the pallet industry is about to get a jolt.
Watch this space. There are tremendous savings to be made and significant environmental benefits to be gained. Full conversion to slip sheets for any supply chain is not going to happen, but a partial conversion for particular product lines is not only desirable, but inevitable - even in Europe.