Stormwater traps haul tons
Simple stormwater‑trap programs are pulling surprising volumes of litter: Australia’s Kwinana nets recovered 370 kg on their first collection, while Melbourne’s 120 traps removed about 3,468 kg of litter — roughly 75,000 large pieces — over six months. (The viral social summary included photos and region‑by‑region tallies of trapped debris.) (x.com)
Stormwater traps are catching thousands of kilograms of litter before rain can flush it from streets into creeks, rivers and bays. (kwinana.wa.gov.au) (melbournewater.com.au) In Kwinana, south of Perth, the city installed two drainage nets at pipe outlets in Henley Nature Reserve in March 2018, then added three more during the 2019-20 financial year at Orelia Oval, Sloans Reserve and Oakley Road. (kwinana.wa.gov.au) The first two Kwinana nets removed 1,690 kilograms of waste in 11 collections between May 2018 and June 2019, and the city said five nets had captured 3,660.5 kilograms across 32 cleaning cycles for the original pair and 19 for the later three by August 4, 2023. (kwinana.wa.gov.au 1) (kwinana.wa.gov.au 2) The basic idea is simple: a mesh net or chamber sits at the end of a stormwater pipe and catches bottles, wrappers, cans, leaves and coarse sediment while water keeps moving. Melbourne Water says gross pollutant traps are built to capture litter and sediment larger than 5 millimetres. (kwinana.wa.gov.au) (melbournewater.com.au) That matters because stormwater is not sewage treatment. Melbourne Water says rain running off roofs and roads carries litter, oils, detergents, metals and other pollutants straight into waterways, and more than 90 percent of litter found on Port Phillip Bay beaches comes from stormwater. (melbournewater.com.au) The City of Melbourne says up to three billion pieces of litter, or about 2,000 to 3,000 tonnes, are washed into Melbourne waterways through stormwater drains each year. The city says it has more than 20 litter traps in its own drainage system. (melbourne.vic.gov.au) Kwinana’s system is also relatively cheap by public-works standards. The city says each drainage net cost about 10,000 Australian dollars to supply and install, including civil works to improve access. (kwinana.wa.gov.au) But the traps are not a complete fix. Melbourne Water says gross pollutant traps mostly remove large, non-biodegradable waste, do little for dissolved pollution or fine sediment, and need regular cleaning to keep water flowing. (melbournewater.com.au) (melbourne.vic.gov.au) Kwinana has run into that maintenance problem in practice. The city said some nets were damaged after Western Australia’s Containers for Change refund scheme began, because people tried to reach trapped bottles and cans, and the nets were removed in hotter, drier months to prevent vandalism when flows were lower. (kwinana.wa.gov.au) The appeal is that the trash is visible. Kwinana Mayor Carol Adams told the Australian Broadcasting Corporation in 2019 that the city of about 42,000 residents had drawn global attention after photos of the nets spread online, and that the first winter’s haul kept 370 kilograms of debris out of bushland reserves. (abc.net.au) That is why these programs keep resurfacing online: they turn an invisible drainage system into a before-and-after count of what rain would otherwise carry downstream. (abc.net.au) (melbournewater.com.au)
