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).
The in-depth description of the case study
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
NWRM(s) implemented in the case study
Longitude
-1.142012
Latitude
52.992004
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
Monitoring maintenance
Monitoring impacts effects
1
Monitoring location
Unknown
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.
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.
Design & 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.
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
| Land use change type |
|---|
Design authority
| Authority type | Role | Responsibility | Name | Comments | |
|---|---|---|---|---|---|
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.
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
|
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
| Financing share type | Share | Comments |
|---|
Policy, general governance and design targets
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
| Pressure directive | Relevant pressure |
|---|
Policy area
| Policy area type | Policy area focus | Name | Comments |
|---|
Policy impact
| Impact directive | Relevant impact |
|---|
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
| Requirement directive | Specification |
|---|
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.
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
