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Emerging Contaminants in Highway Runoff - AquaWatch and the HazEL Framework

This jointly-commissioned report by Stormwater Shepherds and CIWEM shows that pollution comes from tyre particles, fuel spills and other vehicle fluids, road surface fragments, sediment and herbicides. These contain heavy metals and toxic chemicals such as polyaromatic hydrocarbons (PAHs) which have shown to be carcinogenic and hormone disrupting to aquatic life.

There are likely 100s of thousands, if not millions, of highway outfalls across the world discharging into the water environment. Yet these outfalls are unmonitored and largely uncontrolled, despite the control of pollution from National Highways’ road network being a statutory duty in the UK.

The Challenge: Unseen Pollutants in Highway Runoff

Highway runoff, a complex cocktail of microplastics, heavy metals, hydrocarbons, and other pollutants, often evades traditional monitoring systems until it’s too late. The HEWRAT (Highways England Water Risk Assessment Tool) model has been instrumental in identifying high-risk outfalls and predicting contaminant loads. However, it lacks the ability to detect dissolved contaminants, leading to delayed responses and increased environmental impact.

AquaWatch and HazEL are dedicated to democratising water science to enable multigenerational water stewardship. Our commitment to long-term sustainability and fact based environmental management drives us to innovate and collaborate to improve water quality monitoring.

Our Solution: Continuous Water Quality Monitoring

AquaWatch offers a solution to this challenge through continuous water quality monitoring. Our floating sensors provide real-time data on a spectrum of in-situ parameters, ensuring comprehensive and immediate insights into water quality. These can be used to validate and refine models like HEWRAT using continuous data, significantly enhancing diagnostic capabilities, integrating sediment tracking, and triggering event-based sampling for rapid intervention.

Integrating the HazEL Framework

We are proud to work with the HazEL framework, an innovative model that complements our continuous monitoring systems. The HazEL framework not only assesses current risks but also projects future threats, considering both existing and emerging contaminants. The combination of this event triggered framework with continuous water quality monitoring alerts enables us to better quantify risk, conduct detailed contaminant load simulations under various climatic conditions and provide a proactive and informed approach to water management.

A Collaborative Effort for Greater Impact

Effective environmental protection requires collaboration. At AquaWatch and HazEL we work closely with government agencies, insurance companies, financial institutions, environmental organisations, and community stakeholders to create shorter feedback loops in environmental water management. We are collaborating to reduce risk whilst achieving more efficient outcomes. Our collective efforts ensure that our solutions are technologically advanced, practically applicable, and widely accepted.



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