Effluent storage – we all want to get it right, but there’s a few misconceptions that can sometimes lead us down the wrong path.
Ideally most farmers look at the big picture, and aim for not only storage, but an effluent management system that’s efficient, effective, council compliant and futureproof, with low labour and maintenance requirements. To achieve this the first fundamental rule of effluent storage is to utilise the flow of gravity wherever possible – after all, it’s the one thing that’s guaranteed to keep going even when the power’s out! For this reason, a lined effluent pond will usually be the best option.
Of course there are situations where an above ground tank or bladder tank are the best solution, or they may just be your preferred choice, and that’s absolutely fine! But here’s some common misconceptions to help you make an informed decision…
#1 Safety - Above Ground Tanks or Bladder Tanks are Best
Safety is an important consideration for any effluent storage set up, and it’s easy to see why an above ground tank or enclosed bladder tank would be considered safer – they’re harder to access. All things considered, in actual fact a fenced effluent pond can be just as safe, and the cost of fencing should always be included as part of an effluent pond installation. Both above ground tanks and bladder tanks require monitoring to ensure their structural integrity (which would be dangerous if compromised), and if a pedestal is used to access an above ground tank this could be considered more dangerous than a pond.
#2 Above Ground Tanks and Bladder Tanks Have In-Built Stirrers
Yes, some above ground tanks and bladder tanks come equipped with in-built stirrers, however the misconception is that they are therefore more cost effective. In the majority of cases these in-built stirrers are not effective enough to thoroughly mix the effluent, often leaving a build up of solid nutrients at the bottom of your storage. The most efficient and effective way to utilise all the nutrients is to use a mechanical effluent stirrer. With the addition of a pedestal an electric stirrer can be mounted for above ground tanks, or an over-the-wall extension can be used for PTO stirrers.
#3 Bladder Tanks are a Low Cost Solution
Bladder tanks can certainly be an ideal solution for situations such as swampy & high water table sites where it’s not possible to dig an effluent pond, temporary sites, high rainfall areas where a pond would be prone to overflow, or sites close to residential properties. However they may not be your ideal solution if you’re just wanting to hold off upgrading your current storage to something bigger. Bladder tanks come with a few requirements that need to be taken into consideration such as site preparation, hoses and fittings needed for shifting from port to port, and a high volume effluent pump.
#4 Closed Storage is Best To Prevent Odour
If you’re only focusing on the storage aspect, a bladder tank can certainly contain the effluent smell. However sometimes, as they say, it’s better out than in! On the other side, feedback and experience tells us that all that storing the odour makes it stronger when it comes time for spreading…an offensive odour could be a council compliance issue, so you would need to be careful when spreading near boundaries.
#5 Less Storage Is Required If It is Covered
While covered storage prevents rain getting in, it also prevents evaporation. So in actual fact, under normal circumstances there is not a lot of difference in the amount being stored. Having additional storage has a lot of benefits, especially throughout dry spells, so adding a covering to storage can be a lot of expense for not much value.
#6 Concrete Pond Lining Lasts Longer
Not necessarily. Concrete pond lining certainly is durable, and can last a long time, however the misconception is that it lasts longer than any alternative option. Technological improvements have meant that a good quality HDPE pond lining can last just as long as concrete and is more cost effective for installation and maintenance (should anything go wrong). HDPE liners are compliant with environmental and regional regulations and are designed to last for over 100 years - so installing one of these should last a few generations!
#7 A Concrete Liner Is Needed To Dig Solids Out Of The Pond
The misconception here is that a pond needs the solids dug out. If you have an effective pond stirrer there shouldn’t be any solids accumulating at the bottom of the pond as the stirrer should be able to get the whole pond well mixed. Further to this, a good set up should include a stone trap to capture any unwanted abrasive solids. The stone trap would be concreted for digging out.
#8 Pond Stirrers Will Damage Synthetic/Rubber Pond Lining
While the stirrer propellor can cause damage to synthetic liners if they come into contact, any good stirrer should have a pond liner protection kit available to prevent this from happening.
#9 Bigger Storage = Bigger Expense
Yes, the initial investment of bigger storage will be more, but economically the cost per litre is less. More importantly, we always recommend having more than the minimum requirements for effluent storage. This means you’re covered should there be excessive rainfall, your cow numbers increase, or for any reason you want/need to store for longer than usual (unable to spread/storing in case of drought).