M3 Junction 2, Surrey

Environment Protection

SDS Aqua-Xchange™ prevents pollution of water bodies adjacent to London-bound M3 motorway

Overview

The M3 motorway carries around 135,000 vehicles daily. The particularly busy section between Junctions 2 and 3, recently upgraded to a smart motorway, lies adjacent to St Ann’s Lake near Thorpe Park. This lake forms part of the South West London Waterbodies Special Protection Area (SPA) and borders a Site of Special Scientific Interest (SSSI).

St Ann’s Lake supports protected wildfowl species and offers valuable recreational use. However, historic surface water runoff from the M3 eastbound carriageway has contributed to a decline in water quality, rated ‘Poor’ by Defra in 2022. With 31 outfalls discharging into the lake, the risk of pollution is significant.

What We Did

SDS was appointed to supply an environmentally robust treatment system for surface water runoff. A 500-metre drainage line was installed incorporating SDS Aqua-Xchange™ filtration media, designed to treat runoff from the eastbound carriageway. The system targets soluble and solid-bound pollutants including toxic metals, polyaromatic hydrocarbons, and microplastics.

Site constraints included a submerged embankment, the presence of NRTS cabling, and narrow-lane traffic management. A temporary traffic scheme was extended by 1.9 miles with lane closures and reduced speed limits to ensure safety. Installation proceeded without any delays.

Results

The system now reduces the risk of pollution to St Ann’s Lake, supporting ecological recovery and compliance with environmental regulations. It also contributes to improved flood resilience along the M3, enhancing road safety.

SDS Aqua-Xchange™ delivered a low-maintenance, cost-effective solution with minimal disruption during construction works. It offers a long-term asset for the protection of critical waterbodies adjacent to the national motorway network.

The SDS Aqua-Xchange™ system was selected for the M3 drainage improvement works after considering various alternatives. Key factors in specifying Aqua-Xchange™ included the minimal crew required for installation, ease of installation including simple bag emptying with minimal disruption to local traffic, and absence of required maintenance. Installation in fact proceeded very smoothly despite the challenging site, and we are confident the material will perform well.”

– Iulian Oprea, Senior Project Manager, Connect Plus Services

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