Why is storm water an issue? There’s not much in the way of infrastructure in nature for managing it. Surface runoff form streams and rivers and lakes – that part is visible and makes sense. Where does the rest of the water go? It is held by permeable soils, taken in through plant roots and filtered down until it recharges the aquifer. Urban systems have issues with storm water because we have taken a huge amount of permeable surface area and made it impermeable. This concentration of the flows creates large volumes of water with major impacts on our daily lives and so we as societies build massive pipes underground to collect and direct this water. In Wasagaming this water has been dumped – laden with pollutants – into the main beach area and a number of other outflow points. The proposed solution diverts this flow into Ominik Marsh. Ominik is the last stage in the filtration and cleansing of the waste water and sewage from Wasagaming. What happens when you increase the flow rates of the marsh system by dumping millions of litres of storm water into it every season?
To understand the sources of storm water and conceptualize how big an issue this is I have mapped out the impermeable surfaces in Wasagaming – parking lots, roads, paths and roofs. The large squares in the image show the accumulated total area of each system. Interestingly it came out that parking is a 200m x 200m square, roof areas are a 300m x 300m square while roads are by far the largest at a full half kilometer squared – 500m x 500m. More analysis to come as I use these areas to calculate runoff volume and begin to test ideas about permeable surfaces to reduce storm water volume drastically. Total impermeable surface area? 94 acres – that’s almost 400,000m2.