Innovative Stormwater Management: From Monitoring to Solutions

Abstract

Urban runoff poses flooding risks and pollutes surface water. Extreme weather events exacerbate these problems; in a changing climate and increasing urbanisation, innovation in stormwater monitoring and management is urgently needed. We therefore validated a method for onsite assays with a miniature speaker-sized qPCR instrument and other portable equipment items to rapidly identify faecal pollution marker genes in drainage systems and rivers. We deployed the portable method in a mobile laboratory (‘lab in a van’) and quantified HF183 marker genes for human host associated Bacteroides in river water within 3 h of sampling. We used the mobile laboratory to investigate urban river water and effluents from two storm drains and a retention pond and found significantly higher HF183 gene levels in the older storm drain compared to the river water (6.03 ± 0.04 vs. 4.23 ± 0.03 log10 gene copies per 100 mL). Basedon such qPCR methods and next generation sequencing (NGS) with the memory-stick sized MinION, we investigated spatiotemporal variation in the bacteriology of the urban river Ouseburn for different weather conditions. We found that the river microbiome of the Ouseburn changes from mainly freshwater bacteria during dry weather to mainly faecal bacteria during storm events. For a storm event, we matched >70% of bacteria in the Ouseburn where it flows through a public park to those found in combined sewer overflow (CSO) discharge. Nature-based solutions are sustainable practices for stormwater management to reduce flood risks whilst minimizing pollution. We designed an innovative ‘pollution munching’ permeable pavement with 2% activated carbon (AC) amendment in the subbase, which showed significant total nitrogen and nitrate reduction from leachates compared with a conventional sand base permeable pavement. Hydraulic tests showed that the AC amended system still met the design criteria for permeable pavements, making it a promising proposition for stormwater management.