Oslo. The Fjord City citizens. 8 main rivers 2 WWTP km waste water pipes. 55 % combined systems. 45 % separate systems.

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1 Frode Hult, Demo Manager (Senior Engineer) City of Oslo, Water and Sewerage Works PREPARED Alliance Forum no. 2 Aarhus,

2 Oslo The Fjord City citizens 8 main rivers 2 WWTP 2250 km waste water pipes 55 % combined systems 45 % separate systems 218 CSO s 93 pumping stations Prepared enabling change 2

3 Challenges Climate change + a growing population + a tighter city/ more impervious surfaces = Faster runoff More basements filled with sewerage More CSO s in operation Decreasing water quality in rivers and fjord Prepared enabling change 3

4 Adaptations - new master plan sewerage Climate factor for new pipes (1,5) Detention basins & bigger pipes Seperation (less CSO s and basement floodings) Storm water strategy (city planners, VA-utility, road and park planners) High rehabilitation rate (1,6 %) Tunnel model sewer system PREPARED Prepared enabling change 4

5 WP Integrated real time control of sanitation systems in Oslo WP Increasing the capacity of a wastewater treatment plant in Oslo by process transitions during high flows Prepared enabling change 5

6 Goal Possibility for real time control of the tunnel system in order to optimize temporary storage of sewerage (use the storage volume) to minimize CSO s Modeling the tunnel system and surveillance and integrating control systems Prepared enabling change 6

7 Bekkelaget WWTP VEAS WWTP 7

8 Model structure Diurnal flow P P Bekkelaget WWTP Main interseptors Catchment type Combined Separat Storm ca 200 delfelt 8

9 Rain gauges and flow meters P Catchment Bekkelaget WWTP - built area P Bekkelaget WWTP Main interseptors Flow monitoring 2012 Flow monitoring Permanent rain gauge station Mobile rain gauge

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11 Goal Minimize CSO s to the Inner Oslofjord during extreme rain fall Demonstrate the interaction and optimalization between operation of the existing tunnel system and operational modes at Bekkelaget WWTP Prepared enabling change 11

12 Kværner main CSO Ljan tunnel m 3 Bekkelaget WWTP and tunnels flow scheme today Old sieve BRA WWTP pe Prepared enabling change 12

13 3 operational modes today Operational modes Today Mode 1 dry weather Q < 1,9 m 3 /s - all mechanical, chemical, biological Mode 2 medium flow 1,9 m 3 /s > Q < 3 m 3 /s - 1,7 m 3 /s mechanical, chemical, biological - 1,3 m 3 /s mechanical, chemical Mode 3 max flow 3 m 3 /s > Q < 4 m 3 /s - 2 m 3 /s mechanical, chemical, biological - 2 m 3 /s mechanical, chemical Prepared enabling change 13

14 On-line control system for integration between the Kværner tunnel and Bekkelaget WWTP, optimal operation Prepared enabling change 14

15 2014: Midgard Serpent in operation : Extending the tunnel model to the western WWTP (VEAS) 2020: Extended Bekkelaget WWTP in operation Prepared enabling change 15

16 Midgard Serpent Bekkelaget WWTP VEAS WWTP 16

17 The Midgard Serpent In operation medio km rock tunnel Total of m 3 storage capasity Replacing 9 pumping stations with one Minimizing outlet from 33 CSO s 162 mill. Prepared enabling change 17

18 Kværner main CSO Ljan tunnel m 3 BRA WWTP Midgard Serpent (tunnel) pe ( pe in 2020) Emergency CSO Midgard Serpent m 3 Sieve Prepared enabling change 18

19 In operation in 2020 Designed for pe (treatment plant in pe) Larger drainage volume (Kværner tunnel m 3 + Midgard Serpent m 3 ) gives the extention of the WWTP larger capasity (better cleaning, less outlets) and new real time control possibilities Mode Today 2020 Comments Mode 1 dry weather Q < 1,9 m 3 /s - all mechanical, chemical, biological Q < 3,5 m 3 /s - all mechanical, chemical, biological Full cleaning of all sewerage Mode 2 medium flow 1,9 m 3 /s > Q < 3 m 3 /s - 1,7 m 3 /s mechanical, chemical, biological - 1,3 m 3 /s mechanical, chemical 3,5 m 3 /s > Q < 7 m 3 /s - 3,5 m 3 /s mechanical, chemical, biological - 3,5 m 3 /s mechanical, chemical New possibility to control the sewerage by transfering sewer from the Kværner tunnel to the Midgard Serpent to prevent outlets from the main CSO at Kværner Mode 3 max flow 3 m 3 /s > Q < 4 m 3 /s - 2 m 3 /s mechanical, chemical, biological - 2 m 3 /s mechanical, chemical Q > 7 m 3 /s (up to 9,5 m 3 /s) - 3,5 m 3 /s mechanical, chemical, biological - 3,5 m 3 /s mechanical, chemical - 2,5 m 3 /s via sieve station Q>7 m 3 /s (when Midgard Serpent is full) a further 2,5 m 3 /s can be pumped from the Midgard Serpent via a sieve stasjon before outlet 19

20 Kick-started building of the highly important tunnel model! Pushed foreward the work to connect several models and get an integrated real time control between tunnel system and WWTP s to minimize CSO s to the fjord (bathing quality high on the political agenda Oslo The Fjord City)! Input and ideas from other cities in the project Possibility of using weather radars in the future (we have now 30 rain gauges) «Blue flags» bathing quality in the fjord (future) Prepared enabling change 20

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