Ground Conditions at The Batch: Potential Pitfalls for Development

A large area of stones on the surface of "The Batch" in Hanham

With developers Ashfield Land and Redrow Homes having won their appeal in July 2025 to build up to 140 homes at The Batch (land south of Hencliffe Way and west of Castle Farm Road), concerns about the site's ground conditions are growing. Local residents have shared insights suggesting challenges that could hike costs, cause delays, or even question the project's viability. Here's what we know.

Historical Context: Quarries and Coal Mines

The Batch lies in an area steeped in industrial history. The surrounding slopes leading down to the River Avon were once home to pennant stone quarries, such as Perriman’s Quarry on Castle Farm Road, active in the 19th century. These operations left behind voids, unstable rock faces, and filled workings that can cause ground movement or landslips.

In addition, the area falls within the Bristol Coalfield, where mines such as Hanham Colliery and others once extracted coal from shafts extending more than 400 feet deep. The remnants of these old workings can create subsurface instability or pockets of contamination, both of which pose challenges for modern development.

Recent Observations: Permeability and Testing

Residents report that parts of the site have been “built up” over time with variable materials, and that permeable rock lies close to the surface. During ground testing in 2023, one local witness described a blue dye test in which water poured onto the site appeared in the River Avon below within just 20 minutes.

If accurate, this would indicate extremely high permeability, meaning that water — and potentially pollutants — can flow rapidly through the ground. Such conditions can lead to drainage difficulties, erosion, groundwater contamination, and even flooding risks downstream.

Implications for Development

If these observations are confirmed by further investigation, several potential risks emerge:

·       Ground Instability: The legacy of quarries and mines could require deep pile foundations or ground reinforcement, adding significant costs and causing additional construction noise and disruption.

 ·       High Permeability: Rapid water movement through the soil increases the risk of foundation washout and pollutant migration, necessitating complex drainage and containment systems.

·       Increased Costs and Delays: Additional geotechnical surveys, engineering solutions, and regulatory compliance may inflate budgets. Developers might be forced to phase construction or reconsider viability altogether.

·       Environmental Impact: The site’s proximity to ancient woodland and the River Avon corridor raises concerns about habitat disturbance and water pollution, especially if contaminants migrate through permeable ground.

While the appeal decision noted no objections from flood authorities, provided certain conditions are met, these local observations suggest that significant ground and hydrological issues may not have been fully addressed.

Rest assured, HDGBCS will continue to monitor developments closely and hold developers to account for any environmental or safety oversights.