What are the key factors when developing land near watercourses?

Author:
Andy Busby Project Management Director
020 7640 3042
Read time: 4 mins
Category: Innovate
Author:
James Tinkler Project Management Director
020 7640 3045
Read time: 4 mins
Category: Innovate

Developing land for commercial use which is close to a watercourse brings a unique array of challenges to be considered.

Not only does the work need to meet the requirements set by regulatory bodies, it also needs to ensure the impact on the ecology, flow of water and any potential flood defences is mitigated.

Here, we’ve explored four key considerations when working near watercourses, using our work at 40:40 Link, High Wycombe, and Panorama, Dartford, as illustrative examples.

Mitigating the ecological impact

Preserving natural wildlife is an important factor to consider when developing near to a watercourse. These environments can be home to various rare and endangered animal and plant species, so any work undertaken must ensure the ecology is respected, protected and managed correctly.

Local authorities set preservation requirements for an area, particularly with regard to native plants and protected animal species, and any infrastructure must also accommodate the needs of nearby wildlife. In addition, there can be a requirement to financially support local wildlife trusts to ensure the ecological environment is preserved during and after any development.

At Panorama in Dartford, the surrounding area of the River Thames was a habitat for water voles, which are a protected species across Europe. This meant the voles had to be captured and moved to another part of the country for protection. The on-site bridge also had to be designed with the voles in mind, with tubes built into the structure running from one side to the other to allow the voles to move safely.

To preserve the surrounding wildlife at 40:40 Link at High Wycombe, we were required to use specialist plant seedings of a species which was native to a chalk stream running across the site. More than 400 slow worms from the site were relocated to a preserve on-site area, and nesting tubes for kingfishers were installed

Different authorities for different watercourses

In instances of working near to two watercourses (for example, a river and a stream), varying authorities may have to be involved in the process depending on who has regulatory control. This may result in working with two regulatory bodies to get two sets of approvals. This can prove challenging, not only from a practical perspective (as the two may not have consistent requirements), but also due to the impact it has on timing.

Our work at High Wycombe meant we had to work with the Environment Agency (EA) in relation to the River Wye, and Buckinghamshire County Council with regard to a chalk stream.

Buckinghamshire County Council wanted us to ensure any work being undertaken on the stream didn’t cause any potential pollution or silting. The EA requested for the supporting concrete wall of the river to be replaced with a more natural supportive bank structure using hessian material.

Working in close proximity to flood defences

A key element of working near to any form of watercourse is ensuring there is no risk of flooding exacerbated by the proposed development. This can become increasingly difficult when developing land within close proximity to a flood defence itself.

Flood defences are looked at in their entirety over an entire watercourse, rather than just specific sections in isolation as any development to land near flood defences could impact, undermine or weaken the holistic defence strategy.

This means negotiations are required with the EA during the planning process to ensure a permit is obtained, stating the work can be completed within specific regulations and constraints. Without a permit, the EA can place an injunction on the development works.

Our timings for submitting a planning application at Panorama coincided with full review of flood defences for London for the 21st century, Thames21 (T21), meaning our development was considered in the context of a much larger project. As part of T21, the height of flood defences near to the site would have to be increased within the next 50 years.

The proposed plans originally set out by the EA in relation to the defences required drainage to be installed on our development site. However, this would have fundamentally impacted the land and make our scheme unviable. We offered an alternative solution to this which did not impact the site, and that the EA was happy to accept.

Our works were considered by the EA in the context of both immediate impact and also to ensure our site was futureproofed for any work the EA wished to undertake within the next 50 years. This had design implications on our scheme.

Changing the flow of water

A major challenge can arise if the flow of a watercourse needs to be altered. With any alteration to the flow, the consequences of how this may impact upstream and downstream areas need to be taken into consideration to mitigate the risk of flooding.

At 40:40 Link, a culvert pipe containing a chalk stream ran across the site and connected to the River Wye. An historic residential planning application had made a feature out of the stream, and the planners insisted this was carried over for the commercial use.

The stream was deculverted and, at the insistence of the planners relaid as a meandering stream, causing implications to the overall flow of the stream, its banks and the rise of the land. We successfully completed the work on the stream to meet the requirements set by the planners.

Overcoming the challenges for successful speculative development

When developing land near to a watercourse, the ecological, environmental and regulatory impacts must be taken consideration. However, with strategic planning and agreement with the necessary authorities, any obstacles can be overcome and allow commercial development on the land to commence.

Chancerygate has extensive experience in developing land with complicated technical constraints to be overcome to enable speculative commercial development. For more examples of our expertise in technically challenging projects, read our Gateway article on the remediation work undertaken at Tonbridge Trade Park in Kent.

If you are aware of a site that could be transformed using our expertise, please contact James Tinkler on jtinkler@chancerygate.com T:020-7640-3045 or Andy Busby on abusby@chancerygate.com T:020-7640-3042

Find out more about our existing development portfolio on our Current Projects page.

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