Stormwater management programme of Turku Olli-Pekka Mäki

Transcription

1 Stormwater management programme of Turku Olli-Pekka Mäki

2 Background of stormwater programme The stormwater programme was prepared during 2008 in working group consisting members from waterworks department, real estate department, city planning department, buliding supervision department and environment department Programme was adopted by the city council in 2009

3 Background of stormwater programme Climate change is predicted to raise the sea surface level and increase the amount of rainfall in Northern Europe Sea level rising and increasing amount of stormwaters cause flooding and increase drainage problems in dense urban environment Preliminary evaluation of stormwater flooding is going on, based on EU-directive and national legislation Stormwaters in sewer system cause problems in wastewater treatment plant and reduce the effectiveness of the purification processes The groundwater surface levels in urban areas are falling down because large amount of the coming rainwater are not infiltrating into the ground due to the landcover changes (paved yards, roads etc.)

4 Areas of risk of sealevel rise in Turku City Center < 1 m asl 1-2 m asl Environmental and Planning Department m asl

5 Objectives of Turku stormwater programme Prevent the disadvantages of flooding Maintain the ground water levels Secure the regional and local drainage of areas Prevent the access of harmful substances into stormwaters Increase the use of surface water elements in planning and construction of parks and greenery areas Stormwater as a resource of landscape planning, in irrigation systems or in management of wetlands Preserve the quality and amount of small ponds, streams and springs Reduce the amount of storm water in wastewater networks and treatment plant processes

6 Wastewater sewer network 530 km

7 Stormwater sewer network 460 km Combined sewer network 58 km

8 Priorities in stormwater management 1. Stormwaters are managed and utilised in the area where they are formed infiltration, leaching beds etc. 2. Stormwaters are led with methods which are slowering and delaying flow velocity Balancing tanks, dikes etc. 3. Stormwaters are led to wetlands / basins via green areas before they are led to stormwater sewer or dikes etc. 4. Stormwaters are led via stormwater sewers straight to the waterbodies

9 P-place Building Case-study: New Case-study: New hardware shopping hardware shopping center Mustionkatu center Mustionkatu Building project Building project Proposals of constructor total area of the building for stormwater treatment: site is m 2 asphalted area (parking) building of m 2 leaching fields building of rainwater roof area of buildings reservoirs to slow m 2 down stormwater velocity area of green areas expansion of m 2 stormwater sewer diameter to slow Building site is situated down stream velocities by the small river of Jaaninoja

10 Actions of Stormwater Management Programme Targets, procedures and actions were defined for each city department dealing with the stormwater issues in Turku Master planning Stormwater management plans based on drainage basins Detailed planning Location of sewage network and stormwater treatment areas Planning and construction of greenery areas, parks Planning of flood routes, maintenance of natural streambeds etc. Building permitting Control and guidance of constructors, local orders for stormwater management Environmental management Study of stormwater quality Municipal orders concerning stormwater quality or treatment Waterworks department Measures to reduct amount of stormwater in wastewater sewer network Prevention of floods in stormwater network

11 Thank you!