This is why Nodra has now installed a tailor-made Uponor Vault as a part of a climate project ongoing in the Smedby area in Norrköping. This project is called Smedby Klimatanpassning – Smedby Climate Adaptation. Among other things, it aims to take care of polluted stormwater before it reaches the Baltic Sea. With dimensions of 3,500 x 8,000mm, a maximum flow of 1,600 l/s, and an optimised purification flow of 160 l/s, this is the largest Uponor Vault installed in Sweden to date. The vault’s intake and outfall pipes measure 1,000mm. In addition to this, Nodra has also installed three Uponor Vaults in dimensions of 3,000 x 6,000mm in a new residential area in Norrköping, the Inner Harbour, to purify stormwater before it flows into the Motala River.
A three-step process
The Uponor Vault effectively collects sediment and particlebound contaminants carried by stormwater run-offs. The first purification step consists of a coarse grid where coarser particles such as leaves and branches are captured. After the coarse grid, there is a sediment pocket that collects sediment from the stormwater. The final step consists of 12 tailor-made pipe filters – the number of filters is set based on the maximum flow the vault should have – with Filtrate P (Filtralite). The water is forced through the filters before it flows out of the vault and into the recipient. The goal is that before ending up in the Ljura Stream, the water is so clean that it does not exceed the EIA environmental quality standard. “The most harmful kind of stormwater is the so-called ‘first flush’ from the top layer of the asphalt that comes with heavy rain. Among other things, it contains heavy metals and salts
that flow directly into our stormwater chambers and then into rivers and streams. We want this first flush to get stuck in the filters,” explains Helena Aspdahl, Project Manager at Nodra AB. “This is a pilot project to investigate the purification effect of the vault by taking samples of stormwater before and after the treatment. When we know more, we can decide if maybe a different type of filter or an adjustment of some kind is needed. Also, we have to consider how to most effectively maintain the vault,” says Helena Aspdahl.