Sustainable stormwater management and green infrastructure in Fornebu, Norway

Climate zone
cool temperate moist
Mean rainfall
778
Mean rainfall unit
mm/year
Average temperature
6
Mean evaportranspiration
200
Mean evaportranspiration unit
mm/year
Mean runoff
0,00256849313154817
Mean runoff unit
600 - 750 mm
Average imperviousness
40
Type
Actual Test Site
Light or indepth?
In-depth
Average slope range
0-1%
Vegetation class
grass/turf
Administrative annual cost information
Administrative costs are not known
Application scale
City
Performance timescale
Immediate
Area (ha)
340
Area subject to Land use change or Management/Practice change (ha)
340
Size unit
ha
Design capacity description
The systems were designed based flows expected with a 1 year return period for channels and a 20 year return period for detention ponds. The average runoff was based on estimates of daily summer rainfall between 1957 and 1995. The wet ponds had design criteria of 230 m3 per effective hectare.
Basis of design
The NWRM are deisgned to treat a range of events with return times ranging from 1 to 20 years. Design criteria are based on long-term average summer rainfall.
Constraints
Winter conditions, snow and ice are a challenge to the implmentation of sustainable urban drainage systems at Fornebu and other northern cities.
Favourable preconditions
Having a brownfield site and a governance environment favorable to sustainable multi use urban landscape were key factors in the success of Fornebu.
Crop rotation
none
Design land use change
Land use change type
Discontinuous urban fabric
Design authority
Authority type
Other
Role
Initiation of the measure
Name
Statsbygg
Comments
Statsbygg is the Norwegian Directorate of Public Construction and Property
Authority type
Other
Role
Implementation
Name
Statsbygg
Authority type
Other
Role
Financing
Name
Statsbygg
Authority type
Other
Role
Determination of design details of the measure
Name
City of Oslo
Authority type
Other
Role
Determination of design details of the measure
Name
Municipality of Baerun
Key lessons
Success was dependent on communication between different levels of government and a clear vision for a sustainable, multi-use urban environment
Success factor(s)
Success factor type
Financing possibilities
Success factor type
Attitude of decision makers
Success factor type
Attitude of relevant stakeholders
Financing
Financing type
National funds
Financing type
Local funds
Barrier
Barrier type
Lacking coordination between authorities
Driver
Driver type
Organisation committed to it
Driver role
main driver
Policy target
Target purpose
Runoff control
Target purpose
Peak-flow reduction
Target purpose
Pollutants Removal
Target purpose
Oher Societal Benefits
Target purpose
Increase Water Storage
Target purpose
Groundwater Recharge
Target purpose
Improved Biodiversity
Direct benefits information
The Fornebu brownfield redevelopment has clear direct benefits as it provides space for living, employment and recreation in a crowded urban area. The specific benefits of the NWRM in Fornebu are harder to quaknitfy as they cannot really be considered in themselves but must be seen as part of the complete redevelopment picture.
Ancillary benefits information
Key ancillary benefits include more living space and a sustainable multi use urban environment supporting recreation, residential and industrial land use.
Costs investment information
Total investment cost is not known
Costs land acquisition information
No land acquisition costs as land was already owned by Norwegian government
Costs operation maintenance
unknown
Costs total information
Total cost is not known
Ecosystem improved biodiversity
1
Information on Ecosystem improved biodiversity
more aquatic habitat and greenspace
Information on retained water
The total retained volume of water is hard to assess as the Fornebu plan consists of multiple NWRM and Green Infrastrucutre measures
Increased water storage
230
Increased water storage unit
m3/ha
Information on runoff reduction
Large qualitiative reductions in runoff peaks could be expected
Information on Peak flow rate reduction
Large qualitative reductions in peak flow could be expected when compared to the old Fornebu airport
Ecosystem erosion control
0
Water quality overall improvements
Positive impact-WQ improvement
Information on Water quality overall improvements
based on mdeolling results and design criteria
Water quality Improvements Phosphorus (P)
60
Water quality Improvements (P) unit
% reduction pf pollutant
Water quality Improvements Nitrogen (N)
40
Wq Improvements n unit
% reduction pf pollutant
Water quality Improvements Total Suspended Solid (TSS)
80
Water quality Improvements (TSS) unit
% reduction pf pollutant
Water quality Improvements Copper (Cu)
65
Water quality Improvements (Cu) unit
% reduction pf pollutant
Water quality Improvements Zinc (Zn)
45
Water quality Improvements (Zn) unit
% reduction pf pollutant
Soil quality overall soil improvements
Positive impact-SQ improvement
Information on Soil quality overall soil improvements
improvements related mainly to brownfield cleanup and removal of 200000m3 contaminated soil
Information on Soil quality overall soil pollution
brownfield improvement included removal of contaminated soil, PAH, oil and deicing fluids were all problems

Partners

Logos of all partners of NWRM project