CANAL Water Purification Footbridge proposal
Location: Hermitage Museum Amsterdam, 2010 competition
Water management is still the most important function of Amsterdam canals. Without them, the city would drown. Circulating the water is also vital for sanitary reasons. In the days when windmills had to do the job, the stench of the water could become unbearable in periods with little wind or rain.
Three times a week, 14 of the 16 existing waterlocks around the city close up, so clean water can be pumped in from the big lake IJsselmeer. The current that is created pushes the dirty canal water out through the open locks on the other side of the city. Specialized cleaning boats with big scoops and nets patrol frequently clean surface debris. Since 2005, all the houseboats in the city are connected to the sewer system.
The cleaner water has attracted 20 different species of fish and crab that live a healthy life below the surface. Water birds like herons, ducks, coots, gulls and cormorants also feed and live on the canals.
The bridge proposal uses this as a design criteria, the form of the proposed bridge follows a water vortex, which pumps dirty canal water through and round the steel tubes which filter it and create a current which helps with the sanitation of the canals especially when they are flushed 3 times a week. The bridge acts as a pump pushing dirty water out through the open locks on to the other side of the city, where the cleaning boats patrol and clean the debris. The bridge acts as a reservation for birds which in recent years have been attracted to the cleaner water in the canals.
The coffee shop and the steel ribbed frames that wrap around the bridge reflect the constant movement in the city, bicycles are hoisted up into the frames waiting to be repaired. The coffee shop is an orange water tunnel which has inner reinforced etched glass panels that mimic that give the feel of being underwater. The entire scheme is a piece of reclaimed land, a polder which also allows for people to sunbathe and relax, like an reclaimed urban beach.
Originally the design has been adapted from a water irrigation pump/bridge to be applied to HoldenManz wine estate in Franschhoek in Cape Town, a bridge which filters water in order to irrigate the surrounding vineyards, the original design commissioned by the wine estate has been adapted to Amsterdam in order to help purify the canals and most importantly aerate the water and help with the flushing/movement of the canal water through the city when the locks are opened 3 times a week. The bridge offers a bicycle repair shop and a cafe open to the public as well as a sustainable bridge that offers a service to the city and the neighbouring environment. The hydraulic pumps direct canal water through the series of filters embedded within the frame which aerate and return the water into the canal, cleaner and more hygenic most importantly deterring stagnant water in the city. Rehabilitation of canals is an important step to support and understand the potential of Amsterdam canals.
The bridge aims to increase contact between water and air, thereby dissolving oxygen into the water while the water is flowing. Aeration is achieved jetting water into the air using a pump, or lifting water using a rotating wheel, or dropping water back into the canal from a height. This technique prevents stagnation and pollutants from settling onto the canal surface aiding water circulation and the flushing of canals.