In the 5th edition of our Grain Bunker Storage feature we are going to look at a part of Grain Storage that is vitally important but often forgotten…
Ground Sheets or Liners (as they are often called) are a waterproof lining laid across the floor and walls of a bunker to prevent moisture entering the grain from below as well as avoiding grain being contaminated by the soil. Additionally, once the bunker is tarped with a top cover, the bunker can be effectively sealed to allow for fumigation of the entire storage for insect control.
The long-term storage plans of your bunker will dictate your requirements for a ground sheet:
• On farm storage - that is only to be stored in the short term and has a well drained pad, can be stored without a ground sheet
• Longer term storage - usually requires a ground sheet especially if you intent to fumigate your grain
Grain Bunker Storage Part 5: Lining the Bunker
The Two Options to Line your Bunker
The first is large prefabricated lining sheet similar to the top cover but usually lighter weight. The main advantage of a large ground sheet in one piece of material is the likelihood of a good seal with a single sheet giving greater security and the complete removal of uncontaminated grain when emptying. Additionally, the speed of application is a lot faster.
Alternatively, lining such as black plastic can be purchased on rolls 4m wide x 50m long which is laid across the bunker, overlapped and sealed with tape. Additional widths are progressively laid across the bunker as it is filled and are overlapped 150mm over the previous width. Each overlap is tapped to prevent the grain from pushing the overlaps up and to prevent insect migration.
Usually this type of plastic is un-reinforced and is not as mechanically as strong or as UV resistant as the prefabricated option.
Often there is a tendency to take a short-cut with ground sheets as they don’t seem to be as important as the top cover as they aren’t directly exposed to the elements and the weather.
There are however a lot of issues associated with low quality ground sheets such as:
• Ground water can be a silent killer to your grain. Water can come up through the ground and if a low-quality ground sheet has been used it makes it easy from the grain to be damaged or lost
• Poorer quality fabrics can often have issues with flaking or delaminating of the coating from the base-cloth causing grain contamination
• Low quality fabric can be easily torn during normal handling allowing water and vermin to enter
• Low quality fabric is easier to puncture in normal handling, again allowing water and vermin to enter
These are factors to keep in mind when selecting ground sheets. Higher quality material that are fabricated for strength and long life are often the cheapest option overall.
One last tip, on the larger grain sites, the ground sheets that all the site guys love the best is the old top covers, these work a treat on the bottom of the bunker once they are no longer usable on the top – so hang onto these and get a bit more bang for your buck!
So this sums of this month’s newsletter on Lining your Bunker. Stay tuned for the next edition for the next step in the bunker building process…
We hope it find this helpful; it’s just one of the things we do to give our customers the service they expect!
