Flood Risk Concerns for the Proposed Development at Blundel Lane, Stoke d’Abernon

The proposed housing development at Blundel Lane, Stoke d’Abernon, Surrey, near Polyapes Scout Site, raises serious concerns regarding flood risk and water management. Flooding has become a growing issue across the UK due to increasing urbanization and climate change, and new developments must be carefully assessed to ensure they do not worsen existing flood risks for both new and existing residents.

This article will outline the challenges associated with flood risk, including the impact of increased surface runoff, pressure on drainage infrastructure, groundwater concerns, and potential consequences for local residents.

1. Increased Surface Water Runoff

Current Situation:

• The area around Blundel Lane contains natural green spaces, woodlands, and permeable soil, which currently absorb rainwater effectively.

• As a relatively undeveloped area, rainwater is naturally filtered through vegetation and soil, reducing the risk of flooding.

How the Development Will Impact Flooding:

• Replacing fields and woodlands with houses, roads, and driveways increases the amount of impermeable surfaces, preventing water from soaking into the ground.

• This leads to higher surface water runoff, where rainwater collects and flows rapidly into local drainage systems, potentially overwhelming them.

• During heavy rainfall, water could pool on roads, gardens, and low-lying areas, creating flash flooding risks.

💡 Key Concern for Residents: Will the development have sufficient drainage measures to prevent surface water flooding, or will existing homes and roads be at risk?

2. Inadequate Drainage Infrastructure

Current Situation:

• Local drainage networks in Stoke d’Abernon and surrounding areas were designed to handle the existing population.

• Many rural drainage systems rely on older infrastructure that may not be capable of managing a large increase in water runoff.

• Heavy rainfall events have already caused localized flooding in nearby areas.

How the Development Will Impact Drainage:

• An increased number of homes will put additional strain on the local drainage network, which may not have been designed to cope with the extra demand.

• If the drainage system is not upgraded, it could back up during storms, causing sewage overflows and surface water flooding in residential areas.

• Developers often install attenuation ponds or drainage basins to temporarily store rainwater, but these can become overwhelmed in extreme weather if not designed properly.

💡 Key Concern for Residents: Will there be significant investment in new drainage infrastructure, or will the development rely on an already overburdened system?

3. Risk of Groundwater Flooding

Current Situation:

• The Stoke d’Abernon area has a mix of clay and permeable soils, meaning some areas drain well, while others retain water.

• Some parts of Surrey have experienced groundwater flooding, where rising water tables lead to excess water emerging above ground.

How the Development Will Impact Groundwater Flooding:

• If the development disrupts the natural groundwater flow, it could cause water to accumulate in areas where it previously drained away.

• Excavation and foundation work may alter underground water levels, potentially increasing the risk of basements, gardens, and roads flooding.

• In winter or prolonged wet periods, groundwater can seep into homes, leading to damp issues, structural damage, and costly repairs.

💡 Key Concern for Residents: Has a detailed groundwater assessment been conducted to evaluate the risk of water table changes and underground flooding?

4. Impact on Local Watercourses and River Flooding

Current Situation:

• The area is not directly adjacent to major rivers, but small streams and ditches help manage excess rainfall by directing water away from properties.

• Increased development in nearby Cobham and Oxshott has already put pressure on natural water drainage routes.

How the Development Will Impact Local Watercourses:

• More surface water runoff could increase water levels in ditches and streams, causing them to overflow.

• If natural drainage routes are diverted or blocked, flood risks could increase both upstream and downstream.

• Sediment and pollution from construction sites may further impact local water quality and drainage efficiency.

💡 Key Concern for Residents: Will watercourses be protected and enhanced, or will poor planning increase the risk of flooding in surrounding areas?

5. Climate Change and the Increased Risk of Extreme Weather

Current Situation:

• The UK is experiencing more frequent and intense rainfall events due to climate change.

• Local flood risks are expected to rise as weather patterns become more unpredictable.

How the Development Will Impact Climate Resilience:

• New developments must be designed with future flood risks in mind, not just current conditions.

• If flood mitigation measures are inadequate or short-term, future residents may face flooding problems that could have been avoided.

• Increased flooding events could lead to higher insurance premiums for both new and existing homes.

💡 Key Concern for Residents: Have developers accounted for long-term climate resilience, or are they simply meeting minimum flood risk requirements?

6. Potential Issues with Developer Commitments and Long-Term Maintenance

Concerns with Developer Promises:

• Developers often propose flood mitigation measures during the planning stage but may reduce these commitments later due to cost concerns.

• Some flood protection schemes are only maintained for a few years, leaving future homeowners vulnerable to rising flood risks.

• Attenuation ponds, drainage ditches, and culverts require long-term maintenance, but responsibility for upkeep is often transferred to management companies, who may fail to deliver proper care.

💡 Key Concern for Residents: Who will maintain and manage the flood protection infrastructure in the long term? Will residents be left to deal with future flooding issues?

What Can Residents Do?

1. Scrutinize the Planning Application

• Demand a comprehensive flood risk assessment that considers surface water, groundwater, and climate resilience.

• Check who is responsible for long-term drainage maintenance—is it the local council, a developer-funded group, or a private company?

2. Ask for Independent Environmental Assessments

• Developers may provide optimistic flood projections—residents should push for independent reviews.

3. Push for Infrastructure Investment

• Demand upgrades to local drainage and sewage systems to ensure they can handle the increased demand.

4. Raise Awareness and Object Where Necessary

• Join planning meetings and submit objections if flood mitigation measures are inadequate.

• Work with local councillors and environmental groups to ensure concerns are properly addressed.

Conclusion: A Flood Risk That Cannot Be Ignored

The proposed development at Blundel Lane poses significant flood risks if not properly managed. Without adequate mitigation measures, residents could face:

• Increased surface water flooding

• Strain on drainage and sewage systems

• Greater risk of groundwater and river flooding

• Long-term maintenance challenges