Table of Contents
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Glossary : Click Here
Baseline
The water environment comprises the road drainage system, surface water features such as watercourses, groundwater resources in relation to water supplies and flood risk within the study area. The links between the surface water, groundwater and nature creates a very complex and sensitive environmental setting.
The land within the proposed scheme drains to the River Severn and its tributaries to the west, and to the River Churn, a tributary of the River Thames to the east and south-east. There are areas of surface water flood risk across the route of the proposed scheme. The value of the water environment results from the ground and surface water features themselves, and the biodiversity and landscape features they support.
The understanding of the baseline is being supplemented by ongoing groundwater and surface water surveys. This will give greater certainty about the nature and scale of potential impacts and inform the design of mitigation and enhancement measures.
Construction
During construction, there would be potential adverse impacts on surface water and groundwater flow and quality, due to works including cuttings and trenches near to watercourses and the risk of accidental spillages. The proposed scheme would also require the realignment of Norman’s Brook tributary.
There are established construction practice guidelines to manage pollution risks during construction. Measures to mitigate adverse effects on the water environment during construction would include best practice pollution control measures including emergency spill procedures and the approach to managing storage areas and stockpiles. The appropriate sequencing of works would seek to minimise the impact on Norman’s Brook and groundwater resources. Environmental monitoring of the water environment would be undertaken throughout construction.
Preliminary construction assessment
- Likely temporary adverse significant effect on surface water due to the realignment of Norman’s Brook during the construction phase.
Operation
The excavation of the cuttings through Shab Hill and the top of Crickley Hill may act as a pathway that diverts surface water between catchments, thereby resulting in a change in flows. Drainage design would be developed to maintain existing catchments.
Without mitigation, operation of the road could lead to pollution impacts on surface water and groundwater from road run-off. Road drainage for the proposed scheme would be developed to protect the water environment from highway pollution and to prevent increases in flood risk. A sustainable drainage system would be developed that would discharge into a series of road drainage attenuation basins to provide treatment before allowing water to gradually soak into the ground or flow into a watercourse. This approach would control pollution from road run-off to higher standards than for the current road.
Preliminary operation assessment
- No likely significant adverse effects on the water environment.