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
Typical PSWO
2
Thames Water and EA
operational boundaries
3
Thames Water – Key Facts
• 13,000 km2 (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
“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
Types of misconnection
Bidet
0.3%
Toilet
3%
Other
3%
Shower
4%
Washing
machine
28%
Handbasin
20%
Bath
8%
Dishwasher 9%
Kitchen
sink 24%
Washing machine
Dishwasher
Kitchen sink
Bath
Handbasin
Shower
bidet
toilet
other
6
PSWO discharges
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Surface Water
Domestic
Commercial
Trade Effluent
7
PSWO
8
Consequences for water quality
9
Fish kill
10
Strategy
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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
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
Partnership Project
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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
PSWOs - asset management
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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
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
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Stakeholder education
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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
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Research
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‘Teching up’ pollution tracing
Acoustic Connectivity
EMU – Electronic Misconnections Unit
DGT – Diffusion Gradients in Thin Films
17
Clear protocol
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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:
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–
–
–
–
–
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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
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Alternative Approaches
• Pollution Tracing Method
Statement
• Door to door survey of every
premises in a catchment area
• Pollution Prevention
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Door to door drainage surveys of
all properties in catchment area
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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
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Pyrles Lane before and after
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Pollution Prevention
• Incident & risk reduction, waste minimisation
• Joint TW/EA Pollution Prevention – 1000 visits
per year across region
• Introduction of Best Practice
• From 2006 - new TW schedule of an additional
1500 PP FOG visits per year across region
• We welcome EHO involvement !!!
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Misconnection at FSE
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Drain at fast food outlet
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Polluted Surface Water Outfall
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Slyfield before…
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Slyfield after…
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Environment Agency
Julian Arikans
(Environment Officer - NE Area Pollution Prevention
&Water Quality)
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Environment Agency
Thames Region
• 13,000 km2 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
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Thames Region
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Effluent discharges - 9018
Major industrial processes - 135
Sites using radioactive materials - 274
Nuclear sites - 7
Waste Management sites - 845
Licenced waste carriers or brokers 13093
• Sites of special scientific interest - 462
30
2005 Wastewater Incidents = 264
Pollution Sources
Water
Treatment CSO
PSWO
Foul Sewer
Storm Tank
Pumping Stn
STW
Rising Main
31
Wastewater Incidents
Thames Region
Source (as percentage
of total)
2002
2003
2004
2005
5
3
6
4.5
45.5
53.5
42
41
Rising Main
2.5
4
5
4.5
Sewage
Works
16
8
15.5
17
5
1.5
6.5
4
Storm Tank
9.5
20
4
5
Surface
Water
Outfall
Water Treatment
2.5
3
14
22
13
6.5
2.5
1.5
Combined
Overflow
Foul Sewer
Sewer
Treatment
Pumping Station
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Site address:
Prospect Road (Wells Brook)
Outfall Grid ref:
TQ4160 9234
Eastings:
Northings:
River Catchment:
Roding
Receiving watercourse:
Wells Brook
Width:
Form:
natural
Outfall type:
CSO
Outfall form:
Pipe
Effluent type:
pswo
Local Authority:
Redbridge
EA classification:
LEAP Area:
2
Thames ID:
WL 82
Comments:
900mm outfall - AMP4 CSO site + many misconnections
Date
09/08/2006
181
Visual
Officer:
impact
JULIAN ARIKANS
25
Aesthetics
25
Access
25
Re value
15
Total
90
Rate of flow
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
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PSWO Management Database
•
Uses data from simple outfall assessment
method
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Outfall assessment methodology provides
consistent environmental impact score
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Each outfall on the Thames Water five year
PSWO programme individually assessed
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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
Sites by highest historic score
Thames ID Site Name
WL 70
Highest historic score
8
06/09/2006
90
09/08/2006
80
01/09/2005
70
17/08/2005
67
67
09/09/2005
60
60
28/07/2005
60
05/09/2005
60
08/08/2005
Prospect Road (Wells Brook)
90
WL 153
Monksgrove Loughton
80
WL 53
Eldon Wall Trading Estate Hendon
70
WL 140
NL 275
WL 167
Brent Valley Golf Course 1
Carlton Avenue East
Fordington Road Barnet
60
WL 177
Last visit date
Weir Rd Wimbledon
100
WL 82
Score on last visit
South View Drive Upminster
60
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PSWO Assessment Sheet
NGR:
Eastings
XXXXX
Northings
XXXXX Thames Water outfall number
XXXXXXXXXXX
Digital ref.
Location:
London Borough
Width - (M)
Watercourse:
Man made or natural bed
Outfall size (mm):
(box or pipe)
Outfall type:
(x in the box)
Street name
Headwater
Within culvert
CSO
SWO to river
Rate of flow No flow
(x in the box) Trickle
Low
Moderate
High
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PSWO Management Database
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Highest scoring outfalls may move to priority
investigations
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Tracking of progress until improved outfall
sign-off reached by EA & TW
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EA and TW share information & review
priorities & progress of outfall improvements
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Searches on database
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Outfall investigation detailed information
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Outfalls within river catchments
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Ranking of outfall assessment scores
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PSWO Assessment Sheet
A) - General Visual impact
Score
2
5
15
25
localised around outfall or <10mtr
impact on watercourse >10mtr
impact on watercourse >25mtr
impact on watercourse >100mtr
B) - Aesthetics at outfall
Score
2
5
15
25
faint smell only odour
greywater / foam / scum
strong smell /sewage fungus / litter
faeces / gross litter or fungus
C) - Accessibility / downstream users
No public access / single dwelling access
Minor public access / rear to properties
Public access via footpath or highway
Recreational area / park / water sports
40
Score
2
5
15
25
Seriously polluted outfall
41
Typical polluted outfall
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Outfall ready for sign-off
43
Conclusions
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Defined strategy is key to success
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Strategy must include clear methodology
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Current strategy has enabled TW,EA and EHO’s
to improve the quality of watercourses across
the Thames region
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Conclusions
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This joint approach has enabled all AMP2 and
AMP3 PSWO targets to be met ahead of target
and within budget
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PTMS identifies the most significant but not all
misconnections
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Way forward …working in
partnership
• Strategic partnership with TW,
EA and Local Authorities
…please give us your ideas!
46