Effects of different drainage systems on de-icing salt dilution and detention

De-icing salts are used to avoid slippery road conditions due to snow and ice. However, it must be assumed that these water-soluble chlorides enter the water cycle. On behalf of the Federal Highway Research Institute (BASt), the engineering company Björnsen Beratende Ingenieure, Koblenz, investigated various ways of reducing the de-icing salt concentrations in water bodies of different sizes to a tolerable level. The focus was on wide infiltration and technical drainage facilities.

The investigation confirmed that the broad infiltration of the road runoff has the most effective dilution effect on de-icing salt. The results provide indications for the planning, operation and optimisation of drainage facilities with regard to the detention and dilution of de-icing salt. Therefore, reference to the results achieved will be made in the rules and regulations for road drainage in the future.