Bailrigg Garden Village – identifying groundwater and contamination constraints

Challenge

Lancaster City Council wishes to develop a Garden Village consisting of 3,500 properties on land just south of Lancaster at Balrigg. The development is hoped to be a place for living with a focus on sustainable growth.

As part of the council’s evidence base, we were commissioned to produce a concept drainage design. This included quantifying flood risk, the nature and scale of drainage infrastructure required to develop the area and identifying opportunities for blue-green corridors.

Solution

Bailrigg ground-truth area of Frequent Waterlogging

To inform the design, we undertook a strategic Phase 1 contaminated land study and groundwater assessment. The aim was to classify the vast area of the site based on land contamination, groundwater flooding, and persistent waterlogging risks.

Following a site walk-over and thorough review of historical maps, we were able to develop an understanding of the history of the site and identify potentially contaminated land constraints. Land across the site was classified using a traffic light system:

  • Green- land with a low likelihood of contamination
  • Amber – land that may be subject to contamination and will require site investigation for confirmation prior to any development
  • Red – land on which a contamination source has been identified and action would likely be required to allow development.

A review of the site geology, surface water flood map, and our in-house 5m resolution Groundwater Flood Map was used to identify potential mechanisms for groundwater flooding across the site. The groundwater constraints analysis identified:

  • Areas of perennially or semi-perennially high-water tables which may prove difficult to develop
  • Areas where groundwater may periodically emerge above the surface and are therefore susceptible to groundwater flooding.

Benefit

JBA Conceptual Model of Groundwater Flooding
Conceptual Model of Groundwater Flooding

Bailrigg Garden Village will focus on the delivery of high-quality development with strong links to a series of open spaces. Understanding the site’s history and natural groundwater processes allows the creation of a concept drainage strategy that works with the existing environment:

  • Identifying areas of semi-perennially high-water tables can be used to delineate blue-green corridors
  • Identifying areas with groundwater flooding issues will ensure that key drainage infrastructure can be appropriately cited and not overwhelmed by groundwater.
  • Identifying key contaminated land constraints allows future site investigations to be focussed in critical areas and ensures the design is focussed on suitable land.

Want to know more?

Email Howard Keeble for more information on Blue-Green Strategy or email Michael McDonald for information on contaminated land and groundwater flooding issues. You can also find out more on our groundwater web page.



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