1. General information
Location and description of the intervention
City or FUA
Cardiff
Region
Europe
Native title of the NBS intervention
Trelawney Avenue - RainScape SuDS
Short description of the intervention
Working with Cardiff local authorities, Dwr Cymru Welsh Water's (DCWW) upgraded Trelawney Avenue to its RainScape Sustainable Drainage System (SuDS) (Ref. 4) which alleviated risk to residents and nearby highway which were at a 2 in 10 year flood risk (highly-risky) (Ref. 3). Flooding commonly occurred due to rainwater run-off from the roofs and roads of upstream catchments that drained into a combined, overburdened sewer network. Traditional systems of increasing pipe-size and storage were not cost effective (Ref. 3). A sustainable solution was developed which combined road surface drainage (gullies and slotted grates) and provided water-butts (200 liter reservoirs for roof drains) to 101 properties in Trelawney Avenue and to 75 properties in the upstream catchment (Ref. 3). Additionally, a wall was built to protect properties from the potential effects from surface water run-off (Ref. 1).
Address

Trelawney Ave
Rumney,
Cardiff
CF3 3JQ
United Kingdom

Location
The NBS is situated in an area, with clear delineation of boundaries and a specific shape (polygon). The NBS project can also have more than one area location (more than one polygon, situated close by).
Area boundary
POINT (-3.12876 51.50862)
POINT (-3.12846 51.50825)
POINT (-3.12764 51.5081)
POINT (-3.12702 51.50848)
NBS area image
Source of NBS area image
Arup (Ref. 8)
Total area
332.00m²
NBS area
332.00m²
Type of area before implementation of the NBS
Residential
Website of the intervention
http://www.dwrcymru.com/en/My-Wastewater/RainScape/Other-RainScape-Projects.aspx
Timeline of intervention
Start date of the intervention (planning process)
unknown
Start date of intervention (implementation process)
2012
End date of the intervention
2013
Present stage of the intervention
Completed
Goals of the intervention
The achieved goals of the project were:
- Decreased flood risk to the residents of Trelawney Avenue, which were at a 2 in 10 year flood risk (Ref. 3), as well as reduce flooding of a nearby highway (Ref. 4).
- Rerouted water from the upstream catchment which overburdened the combined sewer system (Ref. 1; Ref. 3).
- Reduced flooding of a nearby highway through upstream solutions at Trelawney Avenue and an upstream catchment (Ref. 3).
- Implementation of sustainable, cost-effective solutions (RainScape SuSD) (Ref. 4) as a part of a larger citywide initiative (Ref. 6).
Quantitative targets
1. Provision of water-butts to 101 properties to attach to guttering downpipes (Ref. 3) as well as to 75 upstream residents (Ref. 1)
2. Decrease flood risk to the residents of Trelawney Avenue, which were at a 2 in 10 year flood risk (Ref. 3), as well as reduce flooding of a nearby highway (Ref. 4).
Monitoring indicators defined
1. Number of homes fitted with rainscape solution - water butts
2. Reduce the risk of flooding to x in y years (Ref. 3)
Sustainability challenge(s) addressed
Climate action for adaptation, resilience and mitigation (SDG 13)
Climate change adaptation
Water management (SDG 6)
Flood protection
Stormwater and rainfall management and storage
Climate change adaptation: What were the goals of the NBS?
Reduce the impacts of climate risks events on urban places and communities
Build resilience
Climate change adaptation: What activities are implemented to realize the conservation goals and targets?
Implement sustainable urban drainage infrastructure (e.g. to make space for water)
Please specify "other Type of NBS project"
Flood risk-reduction and water management through the adoption of sustainable drainage systems. (Ref 3, 4)
Implementation activities
The project’s main activities included installing water-butts to 75 residents upstream in order to divert the water runoff from their homes that was overwhelming the combined sewage system of downstream residents (Ref. 4). Also, to do the same for 101 residents in that downstream community, as well as building them a wall for flood prevention from rainwater runoff (Ref. 3). Finally, for road-water runoff, a network of gullies and slotted grates were installed to reduce runoff from the main sewer system of Trelawney Avenue (Ref. 3). This has provided a cost-effective, sustainable solution to reducing the risk of flooding. (Ref. 3)
Type of NBS project
Creation of semi-natural blue areas
Other
NBS domain and interventions
Ecological domain(s) where the NBS intervention(s) is/are implemented
Grey infrastructure featuring greens
Other
Green areas for water management
Sustainable urban drainage systems
Please specify "other urban green space connected to grey infrastructure"
A wall was built to protect properties from the potential effects of surface water run-off. (Ref. 1) ; The project’s main activities included installing water-butts to 75 residents upstream in order to divert the water runoff from their homes that was overwhelming the combined sewage system of downstream residents (Ref. 4); a network of gullies and slotted grates were installed to reduce runoff from the main sewer system of Trelawney Avenue (Ref. 3)
What is the level of innovation / development of the NBS related to water management?
Medium / High: sustainable urban drainage systems which include water storage and diverts water flooding
Vegetation Type
Flower beds
Garden beds
Other
Amenities offered by the NBS
Unknown
Services
Expected ecosystem services delivered
Regulating services
Flood regulation
Scale
Spatial scale
Sub-microscale: Street scale (including buildings)
Beneficiaries
Primary Beneficiaries
Local government/Municipality
Private sector/Corporate/Company
Citizens or community groups
Other
Please specify "other primary beneficiary"
residents along Trelawney Avenue (Ref 3)
Governance
Governance arrangements
Led by non-government actors
Non-government actors
Private sector/Corporate/Business
Please specify the roles of the specific government and non-government actor groups involved in the initiative
Key project participants are Dŵr Cymru Welsh Water (client) 2. Arup (the design engineer and hydraulic modeller) and 3. Morgan Sindall (the contractor). Cardiff County Council was engaged in the scheme at an early stage (ref 3).
Key actors - initiating organization
Private sector/corporate actor/company
Land owners
Utility company
Key actors - Other stakeholders involved (besides initiating actors)
Local government/municipality
Private sector/corporate actor/company
Citizens or community group
Land owners
Utility company
Participatory methods/forms of community involvement used
Dissemination of information and education
Consultation (e.g. workshop, surveys, community meetings, town halls)
Policy drivers
NBS intervention implemented in response to an Regional Directive/Strategy
Unknown
NBS intervention implemented in response to a national regulations/strategy/plan
Unknown
Please specify the national regulations/strategy/plan
The NBS
NBS intervention implemented in response to a local regulation/strategy/plan
Unknown
Mandatory or voluntary intervention
Voluntary (spontaneous)
Enablers
Presence of specific city-level GI/NBS vision/strategy/plan - mentioned in connection to the project
Unknown
Presence of specific city-level GI/NBS section/part in a more general plan - mentioned in connection to the project
Yes
Please specify the general plan with GI/NBS section
21st Century Drainage Programme by Water UK (Ref 4 and Ref 6). It is mentioned that the vision of the 21st Century Drainage Programme is to enable the UK water industry, in partnership with the UK’s governments and regulators, to make plans that will ensure the sustainability of drainage infrastructure in the future (Ref 6)
If there is a relevant strategy or plan, please specify the theme / type of the plan.
Water regulation strategy
Please specify other vegetation type
Properties upstream of Trelawney Avenue by donating water butts to residents and re-directing the roofs’ downpipes into water butts. Installing water butts at each of the properties upstream would remove surface water from the combined network and lower the risk of flooding along Trelawney Avenue. The water butt set includes a 200 litre water butt, a stand, a connector to the down pipe, porous pipe and nonporous pipe. Once the water butt is fitted to the downpipe using the downpipe connector, the section of non-porous pipe is fitted to the tap at one end and the porous pipe at the other end, which is then laid around the outside of the gardens or flower beds. (ref 3) surface water drain which intercepts surface water from the roads going into the network and redirects it into an existing surface water network (ref 1)
Presence of city network or regional partnerships focused on NBS - mentioned in connection to the project
Unknown
Presence of GI / NBS research project - mentioned in connection to the project
Unknown
Subsidies/investment for GI / NBS in the city - mentioned in connection to the project
Unknown
Co-finance for NBS
No
Co-financing governance arrangements
No
Was this co-governance arrangement already in place, or was it set up specifically for this NBS?
Not applicable
Financing
Total cost
€100,000 - €500,000
What is/was the Cost/Budget (EUR) of the NBS or green infrastructure elements?
The total scheme cost £433,000. (Ref. 1) Approximately equal to 491763 Euro provided by Welsh water (Ref. 1)
What are the total amount of expected annual maintenance costs?
Unknown
What is the expected annual maintenance costs of the NBS or GI elements?
Unknown
Please specify cost savings
Unknown
Please specify total cost (EUR)
The total scheme cost £433,000. (Ref. 1) Approximately equal to 491763 Euro provided by Welsh water (Ref. 1)
Source(s) of funding
Corporate investment
Type of fund(s) used
Direct funding (grants, subsidies, or self-financed projects by private entities)
Non-financial contribution
Unknown
Business models
Risk reduction model
Which of the involved actors was motivated by this model?
Public actor (e.g. municipality)
Private for-profit actor (e.g. firm, insurer)
Citizens / local communities
Type of innovation
Technological
Infrastructural innovation
Please specify technological innovation
Properties upstream of Trelawney Avenue by donating water butts to residents and re-directing the roofs’ downpipes into water butts. Installing water butts at each of the properties upstream would remove surface water from the combined network and lower the risk of flooding along Trelawney Avenue. The water butt set includes a 200 litre water butt, a stand, a connector to the down pipe, porous pipe and nonporous pipe. Once the water butt is fitted to the downpipe using the downpipe connector, the section of non-porous pipe is fitted to the tap at one end and the porous pipe at the other end, which is then laid around the outside of the gardens or flower beds. (ref 3) surface water drain which intercepts surface water from the roads going into the network and redirects it into an existing surface water network (ref 1)
Novelty level of the innovation
The innovation is copied/derived from previous initiative(s) with substantial adaptation
Please specify novelty level of the innovation
stated by Welsh Water's website (rainscape) Ref 1) : Having learned from the international examples of surface water schemes in Malmö, (Sweden) and Portland (Oregon, USA). Welsh Water created their own range of surface water solutions - RainScape solutions, which can be incorporated into new developments, or installed into the existing sewer systems.
Replicability/Transferability
Ambiguous (e.g. multiple interpretations)
Please specify Replicability/Transferability
stated by Welsh Water's website (rainscape) Ref 1) : Welsh Water created their own range of surface water solutions - RainScape solutions, which can be incorporated into new developments, or installed into the existing sewer systems. Likely to be replicated in other areas as a part of this scheme.
Impacts, benefits
Environmental impacts
Climate change
Strengthened capacity to address climate hazards/natural disasters
Environmental quality
Improved waste management
Water management and blue areas
Increased protection against flooding
Improved stormwater management
Enhanced protection and restoration of coastal and marine ecosystems
Please specify other economic impact
The Flood and Coastal Erosion Risk Management in Wales (2011-2014) strategy used the RainScape system’s implementation in Trelawney Avenue as an example of a positive cost-saving measure, with the intervention being one-third of the cost of other potential interventions (Ref. 5)
Description of environmental benefits
The main impacts of this intervention were related to risk reduction. No direct monitoring has taken place in order to determine a quantifiable impact of the intervention, other than in risk reduction itself. Prior to this intervention, the combined sewage system posed a risk of 2 in 10-year risk. This left some residents at risk level DG5, which is internal flooding, meaning that there would be sewage coming into the property. Further, at least two homes were at the SEF risk level, or “serious external flooding”. The interventions taken reduce risk in the area to only 1 in 20-year flood risk (Ref. 3). While speaking generally, the Chris Jones, the CEO of Dwr Cymru Welsh Water has also indicated that reduced flooding through the RainScape system helps biodiversity as well as natural regeneration (Ref. 2), although no specific monitoring has taken place to see if this impact is true for Trelawney Avenue. As mentioned by the Welsh government in their 2011-2014 Flood and Coastal Erosion Risk Management strategy, more rain and flooding are predicted for Cardiff (Ref. 5); thus, the benefit of increased resilience to climate change, while immeasurable, has been taken into account.
Economic impacts
Unknown
Other
Description of economic benefits
The Flood and Coastal Erosion Risk Management in Wales (2011-2014) strategy used the RainScape system’s implementation in Trelawney Avenue as an example of a positive cost-saving measure, with the intervention being one-third of the cost of other potential interventions (Ref. 5). Three options were considered, including: upsizing the sewers (costing £897,537); online storage (costing £689,640); or surface water removal (costing £1,070,311). While these interventions would reduce risk to 1 in 30 years, their costs were prohibitive (Ref. 3). The project opted instead for water butts (which hold 200 litres of water from roof-water drains); and a surface water sewer (costing £158,209) (Ref. 3). While the impacts have not been directly quantified, there is a cost savings to residents too in the form of reduced insurance costs, and likely increased property value.
Social and cultural impacts
Unknown
Description of social and cultural benefits
The social benefits of the intervention have not been directly measured.
Type of reported impacts
Expected impacts
Indicators
1. Environmental: Risk was reduced from a 2 in 10-year flood risk to a 1 in 20-year flood risk (Ref. 3).
2. Economic: Costs of the intervention were 1/3 of alternative interventions (Ref. 3; Ref. 5).
3. Provision of water-butts to 101 properties to attach to guttering downpipes (Ref. 3) as well as to 75 upstream residents (Ref. 1)
Environmental, social and economic impacts
Climate action for adaptation, resilience and mitigation (SDG 13)
Water management (SDG 6)
Coastal resilience and marine protection (SDG 14)
Economic development and employment (SDG 8)
Analysis of specific impact categories
Job creation: The NBS created ...
No information available
Environmental justice: The implementation of the NBS project resulted in ...
Positive distribution of NBS benefits
Negative impacts: Did the project cause any problems or concerns?
No information was found regarding negative impacts of the project
COVID-19 pandemic
No information was found as of July 24 2020; although the pandemic should not impact the intervention, unless maintenance was required.
Methods of impact monitoring
Process of recording NBS impacts
No evidence in public records
Methods used to evaluate the impacts of NBS
Unknown
Evidence for use of assessment
Presence of an assessment, evaluation and/or monitoring process
Unknown
Presence of indicators used in reporting
No evidence in public records
Presence of monitoring/evaluation reports
No evidence in public records
Availability of a web-based monitoring tool
No evidence in public records
Impact assessment mechanism
Name of any specific impact assessment tools
Unknown
Use of GIS in mapping impacts
No evidence in public records
Citizen involvement
Citizens involvement in assessment/evaluation
Unknown
Citizens involvement in the analysis of the assessment/evaluation
Unknown
Follow-up to the evaluation / assessment
Unknown
References
Web links relevant to the intervention
interview-tony-harrington (director)
21st-century-drainage
Documents relevant to the intervention
Attachment Size
Trelawney Avenue Flood Alleviation Project (1.68 MB) 1.68 MB
rainscape_generic_leaflet.pdf (1014.81 KB) 1014.81 KB
List of references
Ref. 1. Dŵr Cymru Cyf. (No Date). Other RainScape Projects. [online]. [Available at: http://www.dwrcymru.com/en/My-Wastewater/RainScape/Other-RainScape-Projects.aspx]. [Accessed on: July 27, 2020].
Ref. 2. Gaines. M. (2013). Welsh Water to manage rainwater with RainScape project. WET News. [online]. [Available at: http://wwtonline.co.uk/news/welsh-water-to-manage-rainwater-with-rainscape-project#.WW2OXYiGM2w]. [Accessed on July 27, 2020].
Ref. 3. Ellis L. (2012). Trelawney Avenue Flood Alleviation Project. UK Water Projects 2012 - Virtual Edition. [No longer available online].
Ref. 4. Brockett. J. 2016. Interview: Tony Harrington, Director of Environment, Welsh Water. [Available at: http://wwtonline.co.uk/features/interview-tony-harrington-director-of-environment-welsh-water#.WW2REoiGM2w]. [Accessed on July 27, 2020].
Ref. 5. Roberts, E., Flood and Coastal Erosion Risk Management in Wales, 2011–2014. [Available at: https://repositories.tdl.org/tamug-ir/bitstream/handle/1969.3/29182/flood-and-coastal-erosion-risk-management-in-wales-2011-2014.pdf?sequence=1]. [Accessed on July 27, 2020].
Ref. 6. Water UK. (No Date). 21st-century-drainage Programme. [Not available online in 2020].
Comments and notes
Comments
4./ Governance: clarification of the Welsh water company status : It is owned, financed and managed by Glas Cymru. Unique in the water and sewerage sector, Glas Cymru is a company limited by guarantee and as such has no shareholders.

2020 comments:
- regarding the specific project, the only direct reference to the project seems to be the Ref. 3. and briefly in Ref. 5. The others speak generally about the utility, etc. Proper citation has been made throughout the document.
- After extensively looking, I was not able to find any updates or meaningful information relevant to this specific intervention, so no new references were added. Instead, I worked to elaborate the sections previously answered, and then answer the new questions.
Pictures of the NBS
/sites/default/files/nbs/images/cardiff%20final.jpg