Location Located in the London Borough of Tower Hamlets, Derbyshire Street runs in an east/west direction, parallel with Bethnal Green Road, E2 6HG.
The eastern end of Derbyshire Street was a dead end section of the public highway. Its primary use was for parking, however with no turning head, minor accidents were frequent and motorists avoided using the space. Being a dead end, with large trees and fencing surrounding the street, fly tipping and anti-social behaviour were common. Figure 1: Photograph of Derbyshire Street looking eastbound June 2013 Figure 2: Photograph looking westbound from Weaver Fields June 2013 Figure 3: Photograph looking westbound from Weaver Fields June 2013
The project resulted from the proposed installation of a new cycle route as well as working with Oxford House to create a new outside space for community events. The project was submitted to the Mayor of Londons Pocket Park Programme in 2013 and won the highest amount of funding for that year.
The aim of the scheme was to create a useable and sustainable space, with specific objectives including:
The pocket park disconnects the east end of Derbyshire Street from the combined sewer system with all surface water dealt with on site. There are six SuDS components used in the pocket park: attenuating planters, permeable paving, small scale green roofs, rain gardens, engineered tree pits and a swale. Below all the SuDS features are listed in more detail, including construction and maintenance and Figures 4 7 show the proposed SuDS scheme. Figure 4: Derbyshire Street proposed layout (click to enlarge) Figure 5: proposed location of SuDS and catchment design (click to enlarge) Figure 7: Visualisation of the proposals (click to enlarge) Figure 8: Connecting the overflow chamber of the attenuating planters to the rain garden via a clay pipe
Attenuating rain water planters
Amount of water storage: 3m 3
Construction details: Made from plastic, with a wooden faade, the planting trays are 8 inches in depth to support growth of small plants, lined with hessian to prohibit soil washing into the tanks. The water storage tank holds 1m 3 of water and is set into the surrounding York stone to provide stability and room for the overflow pipe underground. Down pipes from Oxford house are disconnected and piped into the back of the planters.
Maintenance: Tanks cleared out annually and plants weeded bi-annually. Summer watering of plants may be necessary.
Additional information: Donated by TWU. Constructed by LJ Plastics.
Permeable block paving 45m 2
Amount of water storage: 4.6m 3
Construction details: The permeable blocks are laid on a permeable sub-base. The paving is on a slight gradient so that water is conveyed into the rain garden. There is a perforated pipe at the highest point of the permeable paving, which acts as an exceedance route, if the system becomes saturated. The pipe runs to a gully pot.
Maintenance: Ad-hoc Sweeping by the street cleaners.
Additional information: Permeable paving from Marshalls. Can be used with underground geocellular storage crates.
Rain gardens and tree pits
Amount of water storage: 4.12m 3 for large rain garden and 3.09m3 for the smaller rain garden
Construction details: 1m to 1.2m in depth. 500-600mm of gravel and shingle, with 500mm of rain garden soil consisting of approximately 45% sand, 40% silt, 10% clay and 5% organic matter.
Maintenance: Inlets (spacing between kerbs) need to be kept clear of litter. Weeded three times a year. A wood chip mulch was used for weed suppression and to help retain consistent moisture levels
Small scale green roofs
Amount of water storage: 0.6m 3
Construction details: The roof is approximately 100mm in depth and has a gutter and down pipe at the rear for overflow. The roof is planted and habitat panels are used around the structure.
Maintenance: As it was installed in the summer, the green roof had to be watered for a few weeks. Annual inspection of the structure, roof and guttering is required.
Additional information: Designed and constructed by Green Roof Shelter Ltd.
Amount of water storage: Below the surface 9.02m 3 and in the basins above ground 2.00m 3 Construction details: 1m in depth with 500mm of gravel and 500mm of rain garden soil. As the swale was turfed, it was compacted.
Maintenance: The swale is mowed every 3 weeks in the summer and every 4-6 weeks in the winter.
The SuDS have been blended into the scheme, with the central rain garden and tree pits acting as a pathway through the scheme, linking all the components together. Due to the scale of scheme and lack of space, source control was critical, with all water having to be dealt with on-site.