Rain gardens for the Day Brook, UK

Title Rain gardens for the Day Brook, UK
Description
Preview image No image
Preview image caption
Creators fullname Laszlo Cseh
Contributors fullname
NWRM
Site information
Climate zone
cool temperate moist
Mean annual rainfall
600 - 900 mm
Mean rainfall unit
mm/year
Average imperviousness
100
Type
Actual Test Site
Light or indepth?
In-depth
Average slope range
1-2%
Vegetation class
Predominantly Urban
Design and implementations
Application scale
Other
Installation date
2013
Performance timescale
Immediate
Area (ha)
0.55
Area specifications
The catchment area of the rain gardens is 0.55 ha
Size
148
Size unit
m2
Design capacity description
The scheme was designed to manage surface water runoff from a 1:30 year event. Designed to capture runoff from 5500 m2 of highway
Basis of design
The scheme was designed to manage surface water runoff from a 1:30 year event
Constraints
The available space on the grass verges and budget available were key considerations in the selection of Rain Gardens over other schemes considered such as tree pits or permeable paving. Groundwork undertook a scoping/ feasibility study to consider the options but there is no available documented information.
The original plan for this scheme was to collect runoff from a surface area of 7100 m2, however only 5500m2 was incorporated into the scheme due to restrictions from underground services and a number of mature trees clustered in one section of Ribblesdale Road.
Proprietary water attenuation cells were key to the initial design as they provide significantly higher void space capacity than clean stone. However, budget contraints meant that use of proprietary cells was reduced and replaced by stone fill in a number of gardens.
Favourable preconditions
The availability of the existing grass verge with occasional mature trees along the entire length of the road, allowed the effective implementation and operation of the rain gardens.
Design contractual arrangement
Arrangement type Responsibility Role Comments Name
No information available
Design consultation activity
Activity stage Key issues Name Comments
Design phase
Local residents involvment in design
Participation from local residents in the design and future management of the rain gardens.
Other
Follow up survey
Post implimentation survey
Design land use change
No data
Design authority
Authority type Role Responsibility Name Comments
Financing
Environment Agency
Financial; guidance and ongoing evaluation
Other
Determination of design details of the measure
Nottingham City Council
Construction; Design and ongoing maintenance
Implementation
Groundwork Greater Nottingham
Design; Implementation and community liaison
National water authority
Other
Severn Trent Water
Post construction modelling
Lessons, risks, implications
Key lessons
The purpose of this pilot study was to prove that a retrofit design would work within an existing constrained urban area and will be accepted by both residents and experts. The specific design of these rain gardens and the site layout is shown to work, and could be replicated.

Key lessons identified are that :
- The measure provides proven surface water capture and infiltration, leading to reduced pressure on the local sewer and watercourse.
- Active residents/ stakeholder engagement and involvement during design and construction helps ensure that concerns are being considered and that the scheme will be accepted and valued.
- When delivered as a collaborative project, multiple benefits can be achieved such as knowledge transfer and local involvement and understanding.
- It is important that all involved (from designers to the construction crew on the ground) are clear on what is to be achieved and how, before implementation/ construction begins.
Financing difficulties
1
Success factor(s)
Success factor type Success factor role Comments
Successful coordination between authorities
main factor

The partnership approach between all stakeholders was critical to the delivery of the retrofit scheme and was very effective.
Communication activities
secondary factor

The positive attitude of the local residents and their involvement in meetings as the project progressed ensured support.
Other
secondary factor

The land was already owned by the local authority so there were no land ownership issues.
Financing
Financing type Comments
National funds
Environment Agency
Barrier
Barrier type Barrier role Comments
Limited staff and consultant knowledge
main barrier
There was initial difficulty in getting the Council to accept a different and new approach. However once the approach was clearly explained, the council were fully supportive.
Lacking financing sources
secondary barrier
There was limited time and budget for design and construction of the scheme
Limited staff and consultant knowledge
secondary barrier
The implementation/construction of the gardens was more of a challenge than anticipated, due to lack of experience of contractors.
Driver
Driver type Driver role Comments
Past flooding events
secondary driver
Previous rainfall events had led to property flooding downstream.
Availability of subsidies
main driver
Money available as part of wider Urban Diffuse Programme in the region
Financing share
No data
Policy, general governance
Policy description
Within the highly urbanised area of Nottingham City, a total of 972 properties fall within the Day Brook floodplain, with previous fluvial events leading to property flooding downstream. Ribblesdale Road is parallel to some of the upper reaches of Day Brook, a heavily modified watercourse that has poor water quality due in part to numerous sources of diffuse pollution from the extensive urban catchment. A pilot study was implemented that reduced the volume of surface water flowing to urban drainage systems from the existing highway setting, reducing the volume of surface water flowing to urban watercourses.
Part of wider plan
0
Policy target
Target purpose
Runoff control
Peak-flow reduction
Increase Water Storage
Policy pressure
No data
Policy area
No data
Policy impact
No data
Policy wider plan
Wider plan type Wider plan focus Name Comments
Other plans, such as catchment flood managment plan have been implimented since the NWRM was implimented.
Policy requirement directive
No data
Socio economic
Direct benefits information
The use of rain gardens in a predominantly urban landscape provides a cost effective and adaptable means to reduce flood risk, while providing aesthetic value to highly populated area.
Costs land acquisition information
No land aquisition required, as owned bythe council
Costs operation maintenance
There are maintenance costs accociated with the scheme, but anticipated to be less than the original maintenance costs of the grass verges
Costs operational information
Not quantified
Costs maintenance information
Maintenance is now undertaken by Nottingham City Council.
NWRM measures were designed to be minimal maintenance. To ensure fully operational inlets will occasionally need to be cleared and vegetaion maintained.
Costs disposal decommissioning information
No information provided
Ecosystem improved biodiversity
0
Ecosystem provisioning services
0
Information on Ecosystem provisioning services
Unlikely to be a signficant effect
Ecosystem water supply
0
Ecosystem impact climate regulation
Not relevant for the specific application
Biophysical impacts
Runoff reduction
33
Information on increased water storage
No storage previously
Runoff reduction unit
% Percent
Information on runoff reduction
Increased water storage will provide additional capacity to retain and efficiently remove run off from highways, and infiltrate to ground. This will reduce the volume of water reaching the local sewer and Day Brook. Modelled 33% reduction in flow reaching the sewer for 1 in 1 year event
Information on Peak flow rate reduction
The storage capacity of the rain gardens will result in reduced peak flows reaching the local sewer, as water will be slowed and contained in the gardens.
Maintenance baseflow
0
Information on Maintenance baseflow
Possible increases to infiltration to groundwater from rain gardens, providing groundwater recharge and baseflows to the brook. However the influence is likely to be minor.
Information on Ecosystem flood control volume
Reducing the volume of water reaching the Day Brook in rainfall events will reduce flood risk to downstream homes and businesses. The reduction in flows reaching the sewer will reduce risk of localised sewer flooding.
Ecosystem flood control return periods
n/a
Ecosystem erosion control
0
Water quality overall improvements
N/A info
Information on Water quality overall improvements
Rain gardens are designed to always intercept and treat the, often more polluted, first flush of highway runoff, ensuring this polluted water does not reach the Day Brook or the local sewer. However there is no available data for the quality of water flowing into or within the rain gardens.
Soil quality overall soil improvements
N/A info
Monitoring maintenance
Monitoring impacts effects
1
Monitoring location
Unknown
Administrative annual cost information
Some monitoring is undertaken but no indication of costs has been obtained.
Monitoring parameters
A data logger was installed beneath two of the rain gardens, which allows continuous water depth recording. This monitoring has taken place between May 2013 and September 2014.
Performance
Performance impact estimation method
Laboratory
Performance impact estimation information
Continuous water level monitoring is allowing a short period of data to be collected post-implementation, and will allow future monitoring of any variation in rain garden performance.

InfoWorks CS 2D modelling has been undertaken since implementation, to model the anticipated reduction in the flow reaching the sewer based on the data logger information.
Measures
sources
Nwrm type In-depth
Nwrm geolocation -1.142012,52.992004
General
National Id
United Kingdom_04
Site name
Day Brook, Nottingham
Summary
A rain garden was installed along the verges of a residential road in Nottingham, England. The purpose of the rain garden was to control the rate of runoff and water quality reaching the downstream watercourse (Day Brook).
Location description
The rain garden is located on a residential street in Nottingham, England. Runoff from the road goes to a small stream called Days Brook.
NUTS Code
Derbyshire and Nottinghamshire
RBD code
UK04
Transboundary
0
Data provider
Heather Williams and Katie Hill, AMEC
Longitude
-1.142012
Latitude
52.992004
EEA core metadata
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