Thornes Park, Wakefield

project summary

Wakefield Council engaged the Environmental Protection Group (EPG) and 2B Landscape Consultancy Ltd to provide natural flood management (NFM) and sustainable drainage systems (SuDS) solutions to alleviate the surface water flooding impacting Lawfield Lane and improve sports pitch drainage for Thornes Park, Wakefield.  Runoff generated from the site, and potential underground drainage was accumulating on the low spot adjacent to, and on Lawfield Lane impacting residents and the local community using the park.

the challenge

Thornes Park is a Grade II registered public park, with all proposals needing to regard the setting and character of the heritage features.  This included a protected ridge and furrow features within the park, as well as historic parkland and boundary walls.  All proposals put forward were required to be approved by park management, the council and numerous stakeholders.

the solutions

Our multi-disciplinary team used integrated 1D and 2D hydraulic modelling software, to conduct a feasibility assessment to test the impact of SuDS and NFM interventions. This required a site visit and topographic survey to gain a true appreciation of the constraints and opportunities. This was carried out by Tom Robertshaw, and with this the team were able to represent the proposed works in the hydraulic model, as well as get creative with developing solutions. Given councils strong preference for a natural and sustainable drainage solution, the design team knew the solution would principally involve earthworks within the site to create water storage areas and create the right conditions to avoid waterlogged ground in the playing areas.

The EPG geoenvironmental team delivered a Phase 1 geoenvironmental desk study and preliminary risk assessment for the development of the NFM scheme. This would allow the design team to better understand the ground and soil conditions and therefore the potential for natural infiltration into the ground, without the need for expensive intrusive infiltration tests at this early stage of developing the conceptual designs. The assessment concluded there were some moderate to low risks associated with soil contamination from unknown infilling of land and from previous use of the site. Although the pollutant linkage is deemed either unlikely or a low likelihood, if contamination was present then a human health risk could be posed to park users or local residents. As such we recommended a scope of soil testing prior to construction to ensure the scheme can be developed safely.

Armed with the essential site information, the surface water management options that were developed and evaluated included combinations of sports pitch drainage improvements, earthworks and regrading in line with the SuDS and NFM philosophy, and daylighting of existing culverts on site. Tom proceeded to create the surfaces required to evaluate the baseline and the scenarios in a fully integrated 2D model. This informed the volume requirements and flow control specification which was essential for realisation of the surface water management solution.

A hydraulic review of the proposed options was undertaken to establish hydraulic performance for the frequent rainfall return periods and up to the 1 in 100+ climate change.

The team attended the community engagement outreach session to be on hand to answer any questions surrounding the proposed NFM and SuDS solutions proposed. The designs were presented to demonstrate the multiple benefits and enhancements based on the four pillars of SuDS and NFM.

the results

With the flood risk engineering led by Jacquline Diaz-Nieto, Associate SuDS engineer for EPG with Tom Robertshaw, Flood Risk and Sustainable Water Management Engineer supporting on civils, and landscape architecture led by Bill Blackledge at 2B, the team translated the proposal into visuals used at the public consultation event, speaking to members of the public and stakeholders about the proposals and creating wider awareness of the benefits of SuDS and NFM.

It was a fantastic project to be involved with alongside 2B Landscape Consultancy Ltd. We’re delighted to see the positive impact that SuDS and NFM can have on a public open space and local community, alleviating the threat of flood risk on the site and bringing biodiversity to the area. We look forward to seeing the council take these proposals forward.