The Northern Roots project is the renovation of a 160-acre disused park in Oldham, Greater Manchester. Based in Alexandra Park, part of the area was used for landfill and the remainder was used to store heavy machinery and had been left to overgrow for 100 years. We were commissioned initially to undertake a feasibility assessment that would detail the possibility of the park being open to the public following renovation before being further engaged to help develop the sustainable water management of the site, using natural methods where feasible, to enhance the amenity and biodiversity of a site that is aiming to become the largest urban farm in Europe by creating sustainable economic, social and environmental benefits for the local community.
The Project
Challenges
Part of the reason that the project is a complex one is the fact that a substantial proportion of the park is built on an existing landfill site. Additionally, there is a significant amount of existing infrastructure on the site including the Oldham District Interceptor Sewer (ODIS), Snipe Clough (a culverted waterway feeding into the River Medlock) other large diameter pipework and combined sewer overflows (CSOs).
Due to its history and proposed regeneration, the Northern Roots development will generate a cocktail of pollutants during rainfall events. These pollutants could include hydrocarbons, heavy metals, silts & sediments, herbicides, fertiliser & horticultural wastes, organic materials, and litter; any of which could have a significantly negative impact on the quality of water entering rivers and streams, harming wildlife along the way. Since the site is a former landfill, the amount of water percolating into the ground must be minimised to prevent the mobilisation of leachate and potential contamination of ground water.
As development continues, a significant amount of potential amenity areas have been identified. These include visitor centres, classrooms, a swimming pond and BMX track for the first phase, as well as the subsequent development of urban farm land, community gardens, an area for sustainable energy production, football pitches, a glamping site and outdoor concert venues.
These developments will have an impact on the current hydrological nature of the Northern Roots site and could therefore increase flood risk.
Solutions
EPG has undertaken the SuDS design for the amenity areas on the site, ensuring that flood risk on-site and downstream is minimised; achieved by meticulous calculations to mitigate effects of the 100-year storm event (plus 40% added to peak flows in allowance of climate change). Discharges from these amenities were calculated at greenfield runoff rate in order to ensure that the capacity within the receiving water body is not exceeded.
Within the SuDS designs from EPG, there will be an amenity provided for use by the local community. This could potentially be the use of the swimming pond as an attenuation structure in times of extreme demand, or even a wetland in order to enhance biodiversity across the Northern Roots site. Further water management and SuDS designs are currently under review that would increase the level of sustainability in addition to flood risk mitigation, as well as the potential use of micro-hydro systems and the use of hydropower to generate electricity for the park.
In order to aid cash flow and funding for the project, the development of the project has been split in to a number of segments. Rather than one larger expenditure, it allowed the client to constantly assess spending and helped them to remain within budget. In the early stages, the Northern Roots project was initially funded by Oldham Council but is now completely self-funding.
Results
- The quick and efficient nature of our work meant that there was ample time for liaison with the client to ensure their demands were met to the exact specification. Additionally, all aspects up to now have been completed within the required timescale
- The Northern Roots Project will be an exemplar project that paves the way for other unused green/brown areas to be developed with community focus and sustainability in mind
- Sustainable water management focusing on harvesting, recycling, and storage, has been the central design ethos
- Significant ecological benefits to the site through SuDS designs and the sustainable nature of the green and blue infrastructure
- This also provides jobs, training and business opportunity to the local community
- High quality local produce is grown at the site. The produce, in partnership with Oldham foodbank, is then distributed to those in need across the Oldham area
- Our contributions to sustainability have helped Northern Roots achieve their goal to utilise the site to mitigate climate change, further Oldham Council’s aspiration to achieve carbon neutrality by 2030 and contribute to targets set out in Greater Manchester’s Five Year Environment Plan
