Polluted Surface Water Outfalls -what s the problem?

Transcription

1 Polluted Surface Water Outfalls -what s the problem? Malcolm Dunk Senior Consultant (Wastewater Quality) - Thames Water Utilities and Julian Arikans Technical Specialist (Water Quality) - The Environment Agency Working in Partnership to Protect the Environment 1

2 Typical PSWO 2

3 Thames Water and EA operational boundaries 3

4 Thames Water Key Facts 13,000 km 2 (5,000 square miles) total catchment 67,000 km (42,000 miles) of sewers 350 sewage treatment works 4200 million litres (924 million galls) sewage treated daily 13 million customers 4,800 trade effluent dischargers 4

5 Misconnections Plumbing errors causing foul water to discharge into surface water drains mainly from domestic sources Waste pipes from sinks, baths, toilets, showers, washing machines, dishwashers etc Loosely extended to include foul to surface water overflows or regular misuse of the drainage system Wholly avoidable and detrimental to the environment 5

6 Types of misconnection Shower 4% Bidet 0.3% Toilet 3% Other 3% Washing machine 28% Washing machine Handbasin 20% Bath 8% Dishwasher 9% Dishwasher Kitchen sink Bath Handbasin Shower bidet toilet other Kitchen sink 24% 6

7 PSWO discharges Surface Water Domestic Commercial Trade Effluent 7

8 PSWO 8

9 Consequences for water quality 9

10 Fish kill 10

11 Strategy Partnerships with EA and Local Authorities PSWOs included as part of asset management Specialist contractors pollution tracing Stakeholder education Research Clear protocol for investigation/remediation Alternative approaches 11

12 EHO involvement We have identified EHO involvement in PSWO remediation as crucial to it s success Vast majority of misconnected householders will want to rectify plumbing errors Several cases where we need EHOs to serve notice on householders 12

13 Partnership Project Misconnections Strategic Group alehm Presentation CIEH seminars 2006 raise awareness Develop and distribute best practice and educational material Joint Pollution Prevention Please give us your ideas!!! 13

14 PSWOs - asset management Prioritised in accordance with EA requirements Each improved outfall = single output Each output based on significant improvement Significant improvement initially by visual inspection Pollution tracing by specialist contractors Indicative costs based on a simple formula TW funds project management, pollution tracing Rectification at homeowners expense PSWOs incomplete until overflows also resolved 14

15 Specialist Contractors Experience shows very few contractors can undertake this work effectively Small preferred list of specialist contractors Best results where contractor exhibits determination and care for environment Careful contractor selection underpins PSWO improvement 15

16 Stakeholder education TW / EA websites MSG Misconnections Tool Kit 3 levels of presentations Misconnections Leaflet Links with DIY outlets, schools and colleges Publications in journals and trade magazines Letter drops Newspaper articles local and national TV and radio Bag It and Bin It 16

17 Research Teching up pollution tracing Acoustic Connectivity EMU Electronic Misconnections Unit DGT Diffusion Gradients in Thin Films 17

18 Clear protocol Pollution Tracing Method Statement Recognised as best practice by the EA Water UK SNAP Group national version Project management of a number of discrete phases: Identification of need Preliminary catchment study, scoping, costs Detailed catchment investigations, pollution tracing Local and door to door surveys Drainage alterations Re-testing outfall Publicity 18

19 Alternative Approaches Pollution Tracing Method Statement Door to door survey of every premises in a catchment area Pollution Prevention 19

20 Door to door drainage surveys of all properties in catchment area Only suitable for smaller catchment areas Time consuming Very effective Tends to identify higher % of misconnections than pollution tracing Does not identify overflows on sewer network 20

21 Pyrles Lane before and after 21

22 Pollution Prevention Incident & risk reduction, waste minimisation Joint TW/EA Pollution Prevention 1000 visits per year across region Introduction of Best Practice From new TW schedule of an additional 1500 PP FOG visits per year across region We welcome EHO involvement!!! 22

23 Misconnection at FSE 23

24 Drain at fast food outlet 24

25 Polluted Surface Water Outfall 25

26 Slyfield before 26

27 Slyfield after 27

28 Environment Agency Julian Arikans (Environment Officer - NE Area Pollution Prevention &Water Quality) 28

29 Environment Agency Thames Region 13,000 km 2 area Thames and its many tributaries The region is amongst the driest in the UK. Less than 10% of the land area of England & Wales Nearly a quarter of the population 29

30 Thames Region Effluent discharges Major industrial processes Sites using radioactive materials Nuclear sites - 7 Waste Management sites Licenced waste carriers or brokers Sites of special scientific interest

31 2005 Wastewater Incidents = 264 Pollution Sources Water Treatment CSO PSWO Storm Tank Foul Sewer Pumping Stn STW Rising Main 31

32 Wastewater Incidents Thames Region Source (as percentage of total) Combined Sewer Overflow Foul Sewer Rising Main Sewage Treatment Works Pumping Station Storm Tank Surface Water Outfall Water Treatment

33 Site address: Prospect Road (Wells Brook) Outfall Grid ref: Eastings: Northings: River Catchment: TQ Roding Receiving watercourse: Width: Form: Wells Brook 2 natural Outfall type: Outfall form: Effluent type: CSO Pipe pswo Local Authority: EA classification: LEAP Area: Redbridge Thames ID: WL 82 Comments: 900mm outfall - AMP4 CSO site + many misconnections Visual Date Officer: impact Aesthetics Access Re value Total Rate of flow 09/08/2006 JULIAN ARIKANS Low Much sewage debris and silt around and downstream outfall. Unclear if recent worsening of pollution cleared. Impact visible on Roding - possible d/s downgrade. Pics taken of outfall area and at confluence with Roding 33

34 PSWO Management Database Uses data from simple outfall assessment method Outfall assessment methodology provides consistent environmental impact score Each outfall on the Thames Water five year PSWO programme individually assessed 34

35 PSWOs by Receiving watercourse Deans Brook NL 283 Hale Lane(West) Edgware NL 282 Hale Lane (East) Edgware NL 273 West Way Edgware Total: 3 Dollis Brook WL 105 Windsor Open Space Hendon WL 52 Dollis Road School WL 106 Hendon Avenue WL 110 Waverly Grove D II Hendon WL 90 Dollis Road Viaduct WL 107 Christs College Playing Fields WL 109 Waverly Grove U I Hendon Total: 7 35

36 Sites by highest historic score Thames ID Site Name Highest historic score Score on last visit Last visit date WL 70 Weir Rd Wimbledon /09/2006 WL 82 Prospect Road (Wells Brook) /08/2006 WL 153 Monksgrove Loughton /09/2005 WL 53 Eldon Wall Trading Estate Hendon /08/2005 WL 140 Brent Valley Golf Course /09/2005 NL 275 Carlton Avenue East /07/2005 WL 167 Fordington Road Barnet /09/2005 WL 177 South View Drive Upminster /08/

37 PSWO Assessment Sheet Eastings Northings NGR: XXXXX XXXXX Thames Water outfall number XXXXXXXXXXX Digital ref. Location: London Borough Watercourse: Man made or natural bed Street name Width - (M) Outfall size (mm): Rate of flow No flow (box or pipe) (x in the box) Trickle Low Outfall type: Headwater Moderate (x in the box) Within culvert High CSO SWO to river 37

38 PSWO Management Database Highest scoring outfalls may move to priority investigations Tracking of progress until improved outfall sign-off reached by EA & TW EA and TW share information & review priorities & progress of outfall improvements 38

39 Searches on database Outfall investigation detailed information Outfalls within river catchments Ranking of outfall assessment scores 39

40 PSWO Assessment Sheet A) - General Visual impact Score localised around outfall or <10mtr 2 impact on watercourse >10mtr 5 impact on watercourse >25mtr 15 impact on watercourse >100mtr 25 B) - Aesthetics at outfall Score faint smell only odour 2 greywater / foam / scum 5 strong smell /sewage fungus / litter 15 faeces / gross litter or fungus 25 C) - Accessibility / downstream users Score No public access / single dwelling access 2 Minor public access / rear to properties 5 Public access via footpath or highway 15 Recreational area / park / water sports 25 40

41 Seriously polluted outfall 41

42 Typical polluted outfall 42

43 Outfall ready for sign-off 43

44 Conclusions Defined strategy is key to success Strategy must include clear methodology Current strategy has enabled TW,EA and EHO s to improve the quality of watercourses across the Thames region 44

45 Conclusions This joint approach has enabled all AMP2 and AMP3 PSWO targets to be met ahead of target and within budget PTMS identifies the most significant but not all misconnections 45

46 Way forward working in partnership Strategic partnership with TW, EA and Local Authorities please give us your ideas! 46