Stormwater filter stops plastic getting into waterway
Auckland member, Medical Plastics Ltd, has been monitoring the effectiveness of a new filter in their stormwater drain. In the 5 months since it was installed in March this year, the LittaTrap filter has collected over 2kg of resin pellets, sprues and other plastic debris.
As most of you know, Plastics New Zealand has been running the Operation Clean Sweep programme for around 2 years now. So far we have audited 55 member sites around the country and 33 of those sites have made changes that are protecting our waterways from accidental plastics pollution.
The most common solution we recommend is to install filters inside stormwater catchpits in high risk areas of manufacturing sites. These are areas like loading/unloading zones, waste skips, and regrind operations, where we often see spills of pellets and other plastic fragments. Putting a filter into a catchpit prevents any accidentally spilled material from heading down the drain into your local waterway.
But, we haven’t really known how effective these filters are. So, when East Tamaki member Medical Plastics Ltd installed a LittaTrap filter in a stormwater catchpit we decided to monitor how effective it was. We’ve been emptying and weighing the filter every 6 weeks since March 2017.
Medical Plastics is not a messy operation. Managing Director, John Fowler, runs a tight ship, but as with all plastics manufacturing sites there are inevitable accidental spills. The waste and recycling bins are located in the same area as the loading and unloading zone, all of which flows into the one stormwater catchpit.
In 5 months of sampling we have measured 2.01kg of material collected in the LittaTrap. Apart from the odd ciggie butt and a bit of leaf litter, the majority of that 2kg has been plastic. You can see from the photos below that the Littatrap has been really effective in catching resin beads.
Figure 1. LittaTrap in the site drain at Medical Plastics (left) and the material collected in just 6 weeks from the filter.
John Fowler says; “The cost was really low. For less than $400 we bought peace of mind, knowing that something was in place to stop any accidental spills of material finding its way out into the nearby Tamaki River”. And maintaining it has been very easy - the filter is simply lifted out of the drain every 6 weeks and (after we have weighed it) tipped into a bin for disposal.
We highly recommend installing filter devices like LittaTraps in your site stormwater drains. It is a cost-effective way of protecting our waterways from accidental spills of resin pellets.