Building the bypass didn’t have to mean harming the environment5th May 2022

Building the Caernarfon and Bontnewydd bypass was not simply about improving travel and relieving congestion in the region.

The Balfour Beatty Jones Bros Joint Venture was determined to minimise the environmental impact of the scheme and worked hard to improve and enhance biodiversity in the area.

This included adhering to the Environment (Wales) Act 2016, with measures such as existing tree and habitat protection; woodland, hedgerow, and wildflower grassland creation; provision of bat and bird boxes; wildlife passages and guidance fencing; and ecologically sensitive lighting.

Steve Blunt, environmental lead for Jones Bros, said: “It’s important for us as a company to be as environmentally friendly as possible at all times, and regardless of the size and complexity of any one project.

“The creation of the £135m bypass was a significant development for the region, but we know that schemes this size can cause real damage to the environment, so we worked vigilantly to minimise disruption.

“Indeed, we have put measures in place to improve and enhance biodiversity in the area, which is something we were eager to achieve when the plans were being put together.”

Nature Conservation and Biodiversity

The route passes through habitats which are known to support a variety of protected species including reptiles, birds, bats, water voles, otters, and fish.

To ensure their protection during the construction, protected species licences and method statements were prepared and implemented, overseen by a team of specialists.

Ecological mitigation included 27 safe passages for wildlife, including four provided specifically for bats, as well as:

• Otter-resistant fencing and otter dry-pipes and ledges
• Fish baffles and elver ledges
• 49 bat boxes, bat guidance fencing and bat-friendly lighting
• Amphibian-friendly drainage
• 32 hectares of wildflower-rich grassland, including six hectares created from locally collected green hay

Landscape and Visual Impacts

Landscape and visual considerations influenced the careful design of structures and treatment of embankment slopes, rock cuttings, watercourses, and ponds.

Approximately 170,000 plants, providing around 14 hectares of new native species woodlands and scrub, as well as more than 20 kilometres of new hedgerows, are part of the scheme planting, with the design developed for ecological mitigation.

Noise and Vibration

Extensive monitoring was conducted throughout construction by the environmental team, to protect residential estates close by.

In locations where either noise or vibration had the potential to exceed legal parameters, strategies were deployed beforehand to avoid this. Low-noise equipment was used where possible and working times close to residents were limited. Strategically planted trees will help to decrease road noise impacts on residents.

This proved a success as monitoring data showed that at no time did operations exceed the construction codes of practice.

Water Environment

The bypass is located in an area that includes surface watercourses and protected sites of high importance, groundwater bodies and areas of identified flood risk.

Six main rivers – Afon Rhyd, Afon Plas, Afon Gwyrfai, Afon Rhosdican, Afon Seiont, and Afon Cadnant – are crossed by the scheme, as well as several ordinary watercourses.

A drainage strategy has been implemented to manage the quantity and quality of water through the introduction of measures such as swales, drainage pipe networks, drainage ditches, culverts, and attenuation/treatment ponds along the route, with the design taking into account flood modelling and potential increases in flood risk.

During construction, measures were implemented to minimise the impact of sediment release on water quality, which included the use of geotextile silt fencing, cut-off ditches and check dams, settlement tanks, and straw bales.

Regular water quality monitoring was undertaken throughout the build to identify any problems, while close liaison was maintained with Natural Resources Wales to ensure that the environmental mitigation was suitable for properly protecting the water environment.