Thames Water
Technology Choice for Planned Indirect
Potable Reuse for London
Final Report of the Independent Expert Review Panel
15th March 2013
Glossary of Key Abbreviations and Acronyms used in this Report
IERP
Independent Expert Review Panel
ToR
Terms of Reference
WwTW
Wastewater Treatment Works
WTW
Water Treatment Works
DWI
Drinking Water Inspectorate
EA
Environment Agency
MF
Microfiltration
RO
Reverse Osmosis
AOP
Advanced Oxidation Process
MBR
Membrane Bioreactor
GAC
Granular Activated Carbon
IPR
Indirect Potable Reuse
WRMP
Water Resources Management Plan
DWSP
Drinking Water Safety Plan
EU
European Union
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
Executive Summary
INTRODUCTION
Thames Water’s 2009 Water Resources Management Plan was subject to a Public
Inquiry where the use of reverse osmosis technology for proposed “planned” Indirect
Potable Reuse (IPR) was challenged and consideration of “lesser” technology options
instructed in the Inspector’s report. To ensure that technology choice decisions for
“planned” IPR in the next WRMP (2014 - which covers the 25 year planning horizon
2015 to 2040) are legitimate and transparent, in April 2012, Thames Water convened
an Independent Expert Review Panel (IERP).
BACKGROUND, AIMS AND METHODOLOGY OF THE IERP
The six IERP members, Mike Wehner (US), David Cunliffe (Australia), Joan Rose (US),
John Fawell (UK), Claire Stacey (UK) and Paul Jeffrey (UK) are internationally
recognised for their extensive range of reuse and water quality expertise, gained over
many years. This includes direct experience of working on acknowledged world-leading
“planned” IPR schemes such as in Singapore and Orange County and formulating
water quality regulations and guidance in Australia, USA and Europe/UK. Through a
series of briefings, conference calls, site visits and a 2-day workshop in September
2012, the IERP addressed the Terms of Reference issued by Thames Water :“To consider outputs of relevance from Thames Water research pilot trials and
other available information and advise on the suitability of the approach to
technology selection and the selected technology for full-scale, planned, Indirect
Potable Reuse (IPR) Schemes in London”
It should be noted that the remit of the IERP was specifically to review and comment on
the studies being carried out by Thames Water and not that of a consultancy,
undertaking a feasibility study for Thames Water. The output of the IERP was to be the
considered opinion of a group of experts around a specific set of questions posed in
the given Terms of Reference, and based on a review of documentation provided by
Thames Water. The independence of the views given was considered crucial.
The IERP considered the technical outputs from two Thames Water research plants, i)
a 500m3/d IPR pilot plant at Deephams, commissioned in 2008, trialing Reverse
Osmosis technology and ii) a 570 m3/day, full-scale demonstration plant commissioned
in 2012 providing non-potable water to the Olympic Park, using a Membrane Bioreactor
(MBR) and Granular Activated Carbon (GAC). With respect to future full-scale IPR
plants, the discussions focussed on Deephams sewage treatment works as a potential
location as this had been the most extensively investigated, but with the recognition
that other sites were also being considered by Thames Water. Facilitated by an
Independent Chair, Michael Norton, the IERP approached the task by debating a set of
key questions posed around the Terms of Reference and produced this report.
15th March 2013
i
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
FINDINGS
There is a strong consensus from the IERP on the central conclusions of the review
and the findings on the key questions.
Thames Water’s Approach to Technology Selection
The IERP is satisfied that Thames Water has demonstrated a systematic, logical and
scientifically credible approach to technology selection. However it has made
observations with regard to (i) more use of existing literature as supporting evidence (ii)
additional research on the MBR/GAC option and (iii) the limitations of not knowing the
final reclaimed water re-introduction point. This latter point is particularly important in
terms of the receiving water quality and dilution.
Minimising Risks to Human Health
The IERP believes that there are significant advantages to a RO-based process train
over an MBR/GAC one, especially with regard to removal of microbiological
contaminants and emerging chemicals of concern
Drinking Water Safety Plans (DWSPs)
The IERP urges greater integration of the Drinking Water Inspectorate & Environment
Agency activities with respect to “planned” IPR and support more specific consideration
of sewage treatment works and sewerage catchments within DWSPs.
Thames Water’s Operating Circumstances
The IERP found this component of their work the most complex. With regard to the
target water quality for “planned” IPR, the IERP noted that in international examples a
“de-coupling approach” has been adopted, whereby any new “planned” IPR schemes
are considered differently to existing “unplanned” circumstances. However the IERP
agreed that the adoption of this approach is ultimately a decision for Thames Water to
make, with consideration of the water quality goals they wish to pursue within the UK
context and their interaction with Regulators. A key decision for the Company is what
risk to take in anticipating future regulatory gaols & capacity–building. In addition, the
IERP feels that more focus should be given to operational issues and monitoring for
any full-scale IPR implementation. It was highlighted that pressure groups can derail
implementation of schemes and communications which means that interaction with the
media, customers and the public have to be considered carefully.
Scientific Foundations
The IERP feels that the case for a multi-barrier, RO approach is well established
internationally and Thames Water has not sufficiently demonstrated the efficacy of the
alternative MBR/GAC process for it to be considered an option at this stage. If this
option were to be pursued, even with further trials, Thames Water would be out of step
with current international practice.
CONCLUSIONS AND RECOMMENDATIONS
The IERP is satisfied with the approach that Thames Water has taken to technology
selection to date but have made suggestions to strengthen future work. The IERP is
comfortable with a technology choice including RO for a full-scale IPR plant at
Deephams. The IERP recommends that any other proposed “planned” IPR locations
are considered individually using a risk-based, water safety plan approach to assist in
the final technology choice. The IERP feels that a robust case for pursuing an
15th March 2013
ii
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
MBR/GAC technology option has not been made and is not recognised international
practice. However, it is appreciated that Thames Water has to make its decisions in a
UK context and the Panel agree that more direction from UK Regulators would be
beneficial.
The IERP recommends specific actions to strengthen the IPR research activities,
including systematic literature reviews, improved microbiological work and better
definition of the IPR research goals at Old Ford.
For future full-scale IPR plants, the IERP recommends a number of actions. These
include monitoring to better understand the current natural and engineered water
quality, operational considerations such as reclaimed water re-introduction points,
drought scenarios, DWSP approaches and capacity building. Attention should also be
given to internal strategy decisions and external engagement with the regulators.
15th March 2013
iii
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
Contents
1.
2.
3.
4.
Introduction
Background and Aim of the IERP
Methodology of Panel Working
1
3
5
3.1
3.2
3.3
3.3.1
3.3.2
3.4
3.5
5
6
6
7
7
8
9
Findings
4.1
4.1.1
4.1.2
4.2
4.2.1
4.2.2
4.2.3
4.2.4
4.3
4.3.1
4.3.2
5.
10
Q1: “Is the Approach by which Thames Water has Evaluated
Technology Options for “Planned” IPR Schemes in London
Sufficiently Robust?”
Global Examples of Approaches to Technology Selection
Thames Water’s Approach to Technology Selection
Q2: “How Appropriate is the Choice of Technology for IPR
Schemes in the Context of Minimising Health Risks, the UK
DWSP Approach, TW’s Current Operating Circumstances
and the Scientific Foundations of the Work ?”
Minimising Health Risks
UK Drinking Water Safety Plans (DWSPs)
Thames Water’s Operating Circumstances
Scientific Foundations
Comments Received from Thames Water
During Preparation of First and Second Drafts
Following Issue of Second Draft
Conclusions and Recommendations
5.1
5.2
6.
Schedule
Reference Material & Conference Calls
Site Visits
Old Ford Water Recycling Plant
Deephams Pilot Plant
Workshop
Consolidation of Findings
Conclusions
Recommendations
15
15
17
18
25
27
27
29
29
30
References
Table 1
Table 2
Table 3
10
10
13
32
IERP Members and Backgrounds
Definition of Key Terms/Nomenclature Used in this Report
Schedule of IERP Activities
15th March 2013
iv
3
4
5
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
Table 4
Indicitive Ranges of Log Reductions of Microrganisms for
Different Treatment Steps – IERP View
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Planned IPR Sites in WRMP09 in relation to Thames Water Area
Old Ford Water Recycling Plant
Schematic of Old Ford Treatment Process
Deephams IPR Pilot Plant
Schematic of Deephams IPR Pilot Plant
Simple Schematic of Possible Deephams IPR Re-introduction
Points, 1) to River Lee then Reservoir System and 2) Direct to
Reservoir System
Figure 7 Drinking Water Safety Plans – Consider “Source” to “Customer
Tap”
Annexes
A
IERP Members Details
B
IERP Terms of Reference
C
Briefing Packs 1 & 2 Contents Lists
D
Site Visit Schedule
E
Workshop Agenda
F
Workshop Outputs (raw)
G
Questions Raised by Thames Water
15th March 2013
v
16
2
7
7
8
8
144
17
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
1.
Introduction
Thames Water has a statutory duty to prepare and maintain a Water Resources
Management Plan (WRMP) which shows how the Company will manage and
develop water resources to be able to meet its obligations under Part III of the UK
Water Industry Act 1991. The statutory provisions also enable the UK Secretary of
State for Environment, Food and Rural Affairs to call a Public Inquiry into the plan; a
power which was used in 2010.
At the Public Inquiry, held between June and August 2010, Thames Water’s choice
of technology for potential “planned” Indirect Potable Reuse (IPR) schemes, which
had been researched and piloted for five years at Deephams Sewage Treatment
Works (STW) , was strongly challenged by some who opposed elements of the plan.
Their primary argument was that the selection of Reverse Osmosis (RO) technology
resulted in the “planned” IPR option having both a high cost and high carbon
footprint, and hence, by following the adopted decision-making methodology, it was
less favourable than other options they were objecting to. In addition, the objectors
made much of the widespread practice of “unplanned” Indirect Potable Reuse in a
UK context.
Following publication of the Inspector’s Report of the Public Inquiry, Thames Water
took actions to address the Inspector’s conclusion, that alternatives to RO for
planned IPR should be investigated. The Company was able to extend the scope of
other research projects that were already underway. These included two sites with
Membrane Bio-Reactors and Granular Activated Carbon (MBR/GAC) for non-potable
reuse (BedZED & the Olympic Park) and some other smaller-scale, related research
trials.
On 19 June 2012, the current Water Resources Management Plan (WRMP09), as
amended following the Public Inquiry, was ratified by the Secretary of State for
Environment, Food and Rural Affairs, and included two small planned IPR schemes
within the preferred water resources programme. These schemes are a 25 Ml/d
plant at Deephams STW and a 15 Ml/d plant at Hogsmill STW, to be completed by
2032 & 2029 respectively, with the proposal remaining targeted towards the use of
RO technology. Both recycling schemes are included as part of the least cost plan to
meet the current supply demand gap as there are few alternative schemes of similar
size and comparative cost. However the planning cycle for the next iteration of the
WRMP (WRMP14) is now well underway and some other locations for “planned” IPR
are being considered, such as Beckton Sewage Treatment Works (STW) and Abbey
Mills Pumping Station, and the outcome of the alternative technology trials are also
being assessed.
Figure 1 shows the locations of the planned IPR schemes in WRMP09 and other
locations of relevance for WRMP14.
15th March
2013
Page 1
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
Figure 1
Planned IPR Sites in WRMP09 in relation to Thames Water Area
Potential planned IPR sites in WRMP09
Rye Meads
STW
River Lee
Deephams
STW
Swindon
STW
Abbey Mills
pumping station
Old Ford
far to West
River Thames
Hogsmill
STW
Walton
WTW & reservoirs
Beckton
STW
Crossness
STW
SEA
BedZED
KEY
River Hogsmill
N
Coppermills
WTW & reservoirs
Potential IPR sites (x2)
sewer
tidal limit
Diagrammatic representation only
not to scale
(Diagram Thames Water)
As yet, no final decision has been made on planned IPR scheme location or the
technology choice, although both the RO and MBR/GAC options are being costed for
input into the water resources scheme ranking methodology. Although the choice of
treatment technology is not currently a significant influence on total costs (due to
small plant size), with a potentially larger supply demand gap to address in the next
plan, the robustness and cost of the chosen technology remains a highly important
and controversial issue. It is therefore crucial that any technology choice for planned
IPR can be justified.
Following the challenge at the Public Inquiry Thames Water concluded that the most
appropriate way to ensure that technology choice decisions in this context are
legitimate and transparent would be to convene an Independent Expert Review
Panel (IERP) to review the technology selection process. During April 2012, Thames
Water approached a number of international experts in re-use of treated wastewater
and drinking water quality regulation, and invited them to join an IERP. A UK-based
Chair was included. It is intended that the outputs of the IERP will inform the
proposals regarding planned IPR technology in the draft version of the next WRMP
(WRMP14), which has to be prepared for public consultation by March 2013.
.
15th March
2013
Page 2
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
Background and Aim of the IERP
2.
The aim of Thames Water in the selection process for the members of the IERP was
to demonstrate impartiality and to ensure that a sufficient breadth of experience was
included in what is acknowledged to be a complex area. The final membership of the
IERP was shared with the relevant Regulators and Stakeholders (DWI, EA, OFWAT,
CC Water, DEFRA)1
In selecting the members of the IERP, Thames Water considered that the following
experience and credentials were needed: to be reflected in the IERP’s experience
and knowledge:
• Full scale operational experience of a “planned” IPR scheme;
• Fundamental science around the technologies employed for “planned”
IPR;
• Health-related issues in water reuse;
• Regulation and standards for “planned” IPR schemes;
• Water Quality Regulations and relevant regulations in a UK context;
• Water reuse in a UK and European context; and
• Public Perception and stakeholder engagement perspectives.
Each of the six IERP members fulfilled at least one or more of these criteria and
brought to the discussions personal experience over many years in relevant
research, operation and regulation, including advising or working on full scale
“planned” IPR schemes such as the worlds largest IPR scheme in Orange County,
USA; the Singapore NewWater Project and the Australian Western Corridor Scheme.
A list of the IERP members is provided in Table 1, with more details in Annex A.
Table 1
IERP Members and Backgrounds
Michael Norton – Panel Chair
Global Municipal Water Director, AMEC Environment and Infrastructure; Chair ICE Water Panel
1
Mike Wehner – USA, Planned IPR Practitioner
Assistant General Manager of Orange County Water District (OCWD)
2
David Cunliffe – Australia, Planned IPR Water Quality & Microbiology
Principal Water Quality Advisor, Dept of Health, South Australia.
3
John Fawell – UK, Toxicology, Risk & Drinking Water Quality
Drinking water, environmental contamination and water quality research consultant
4
Joan Rose – USA, Water Microbiology, Water Quality & Public Health Safety
Director/Principal Investigator of Michigan State University Water Quality, Environmental, and Molecular
Microbiology Laboratory.
5
Paul Jeffrey - UK, Public Perception and Reuse
Professor of Water Management at Cranfield University
6
Claire Stacey – UK, UK Drinking Water Regulations & Water Quality
Deputy Chief Inspector of the Drinking Water Inspectorate until 2005 & currently consultant
DWI – Drinking Water Inspectorate, EA – Environment Agency, OFWAT - The Water Services Regulation Authority,
CCWater – Councer Council for Water, DEFRA – Department for Environment, Food and Rural Affairs
1
15th March
2013
Page 3
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
The IERP was issued with Terms of Reference which are to be found in full in Annex
B.
In summary, the IERP was tasked:
“To consider outputs of relevance from Thames Water research pilot trials and
other available information and advise on the suitability of the approach to
technology selection and the selected technology for full-scale, planned,
Indirect Potable Reuse (IPR) Schemes in London”
In doing so the IERP was to answer the following specific questions:
•
“Is the process by which Thames Water has evaluated technology options
for “planned” IPR schemes in London sufficiently robust?”
•
“How appropriate is the choice of technology for “planned” IPR schemes
in the context of minimising health risks, the UK DWSP approach , Thames
Water’s current operating circumstances and the research and technology
scientific foundations?”
It should be noted that the remit of the IERP was specifically to review and comment
on the work carried out and being carried out by Thames Water in response to the
Public Inquiry, and not that of a consultancy undertaking a feasibility study for
Thames Water. The output of the IERP is to be considered the opinion of a group of
experts around a specific set of questions posed in the given Terms of Reference,
and on a review of documentation provided by Thames Water.
For reference a summary of definitions of terms used in this report is shown inTable 2
Table 2
Definition of Key Terms/Nomenclature used in this Report
“unplanned” Indirect Potable
Reuse (IPR)
This is where treated sewage effluent is discharged into a watercourse
and becomes diluted by the normal flow in the receiving waters, which
are subsequently abstracted downstream for treatment in a water
treatment works for drinking water use. This is generally acknowledged
as being a historic legacy and occurs in river systems throughout the UK
It is tacitly accepted by consumers..
“planned” Indirect Potable Reuse
Where sewage effluent is treated to a higher standard and actively
managed, often to a re-introduction point higher up the river catchment
or to an aquifer, to augment water resources for subsequent abstraction
for treatment at a water treatment works for drinking water use.
planned Indirect potable reuse
As the highly treated sewage effluent is re-introduced into a river, aquifer
or surface water storage reservoir before it is re-abstracted it spends
some time in an “environmental buffer”, which is considered as an
additional “barrier”. There can be some ambiguity with this term in
respect of the length of time the reclaimed water is resident in the
environmental buffer. In general the re-introduction to large reservoirs as
part of the water treatment arrangements is considered “indirect” eg in
Singapore NewWater * or as would be for any future planned IPR
scheme using the Coppermills reservoirs.
Note – some Californian Regulators would consider Singapore
Reservoir retention times short enough to be considered “Direct”
although the concept of adequate retention times is changing with the
latest draft regulations from California Department of Public Health
planned Direct potable reuse
Where sewage effluent is treated to a very high standard and reintroduced directly at the inlet of a water treatment works for drinking
water use. This is currently considered to be practised at only one
location worldwide – Windhoek in Namibia - although it is being
deliberated as a future option in California and Texas.
15th March
2013
Page 4
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
3.
Methodology of IERP Working
3.1
Schedule
The IERP broadly followed the schedule of activity included within the Terms of
Reference (see Annex B). Table 3 below shows the sequence of activities which
was followed:
Table 3
Schedule of IERP Activities
Activity
Key Dates
Phase 1 – Panel formation
1
IERP programme finalised by TW
April 2012
2
Panel members approached
11th May 2012
3
In-Principal Agreements with Panel members
mid May 2012
4
Panel constituted
June 2012
5
Relevant agreements / confidentiality finalised
mid June – start Aug 2012
Phase 2 – Panel deliberation
6
Briefing Pack 1 sent to panel members
22nd June 2012
7
Conference call to review Briefing Pack 1
26th July 2012
8
Briefing Pack 2 sent to panel members
31st Aug & 13 Sept 2012
9
Chair one-to-one calls with panel members to review Briefing Pack
2
17th – 21st Sept 2012
10
Panel members review all info. & assemble initial views
31st Aug – 25th Sept 2012
11
Site Visits to Deephams pilot plant and Old Ford WWTP
26th Sept 2012
12
Workshop at Cranfield University
27th & 28th Sept 2012
Phase 3 – Conclusions and Reporting
13
Compilation of draft Panel findings report V1
26th Sept – 12th Oct 2012
12
Draft Panel Findings report circulated to Panel
12th Oct 2012
13
Panel provide comments on V1
12th – Oct 29th Nov 2012
14
Conference call to discuss draft report V1 & comments
7th November 2012
15
Second Draft V1 circulated for comments & final amendments
12th Nov – 22nd Nov 2012
16
Second Draft V2 circulated to IERP members for sign-off
23rd – 30th Nov 2012
17
Draft Final Report (ref Second Draft V2 03/12/12) issued to
Thames Water
6st December 2012
18
Any comments from Thames Water circulated
Dec – Jan 2013
19
Discussions of final refinements to report
Feb 2013
20
Final Report formally issued
15th March 2013
15th March
2013
Page 5
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
The intent of the IERP schedule and method of working was to ensure maximum
benefit from the members input over the allotted time. Given the potentially very wide
subject area the IERP was requested to pay particular attention to the Terms of
Reference and to concentrate on the key reference material provided.
3.2
Reference Material & Conference Calls
The two Briefing Packs issued to the IERP included a range of documents and
reports detailing the background to IPR in Thames Water and on the research activity
undertaken by the Company. The contents of the Briefing Packs are listed in Annex
C.
In addition a 20 minute video of the two key locations that were to be visited,
Deephams and Old Ford, was produced and sent to the panel members, so that they
were able to get an impression of the research sites in advance.
The IERP members were asked to read and absorb the contents of the Briefing
Packs and video, and to seek clarifications through conference calls, one-to-one calls
with the IERP Chair, and direct questions to Thames Water. The IERP members also
volunteered information that they felt could help inform the discussions.
3.3
Site Visits
On 26th September 2012, site visits were made to the plants at Deephams and Old
Ford. These visits gave the IERP an opportunity to see the facilities being used by
Thames Water to research alternative treatment process streams for IPR, and to ask
questions of the Thames Water staff working on these facilities.
Details of the schedules for these site visits are given in Annex D.
15th March
2013
Page 6
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
3.3.1 Old Ford Water Recycling Plant
Old Ford is a 500m3/day plant which “mines” raw sewage effluent from a large sewer
in North London, treats it using a
membrane bioreactor (MBR) and
GAC, and then chlorinates it for
distribution
for
non-potable
purposes, such as toilet flushing and
irrigation on the Olympic Park. It is
also run as a research facility by
Thames Water. with one of the
research projects to examine water
quality after MBR/GAC as a
comparative process to RO.
The
plant is adjacent to the Olympic
Stadium and figure 2 shows a
photograph of the site from the East.
Figure 3 illustrates the treatment
process used at the Old Ford site.
Figure 2 Old Ford Water Recycling Plant
(Photograph Thames Water)
More details can be found in Reference 1
Figure 3
Schematic of Old Ford Treatment Process
(Diagram Thames Water)
3.3.2 Deephams Pilot Plant
15th March
2013
Page 7
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
Deephams pilot plant is a purposebuilt, 600m3/d facility, to research
indirect
potable
reuse.(a
photograph is shown in Figure 4) It
is located on the site of Deephams
Sewage Treatment Works (STW) in
North East London, which is also
adjacent to the River Lee and
Coppermills reservoir complex. The
pilot plant is containerised and
comprises
of
pre-filtration,
microfiltration, reverse osmosis and
advanced oxidation and the feed
source is Deephams STW final
effluent. During the recent research
trials other technologies have been
evaluated such as replacement of
the RO membranes with NF
(nanofiltration) membranes.
Figure 4 Deephams IPR Pilot Plant
(Photograph Thames Water)
A simple schematic is shown in Figure 5
More detail can be found in Reference 2
Figure 5
3.4
Schematic of Deephams IPR Pilot Plant
Workshop
The primary forum for debate amongst the IERP members was a two-day workshop
held at Cranfield University during which the IERP discussed the questions posed of
it in the Terms of Reference. By the end of the workshop the IERP had reached its
draft conclusions.
15th March
2013
Page 8
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
The workshop was convened at Cranfield University on 27th and 28th September and
structured as shown in Annex E.
Workshop attendees comprised:
• IERP Members (Joan Rose, Claire Stacey, Paul Jeffrey, Mike Wehner,
David Cunliffe and John Fawell);
• Facilitator (IERP Chair – Michael Norton);
• Sponsor (Thames Water – Chris Lambert); and
• Reporter (Siân Hills).
The workshop was structured in five sessions with a number of techniques used to
elicit debate and discussion of the subject areas. Additional material and data was
made available should the IERP members wish to refer to them. The discussion
points and outcomes were hand-recorded on flipcharts which were then transposed
into an electronic format. Annex E presents the raw output of these sessions in the
latter format.
3.5
Consolidation of Findings
Subsequent to the Workshop, the IERP Chair worked with the workshop Reporter to
transfer the raw material from the flip charts comments into a draft document which
was issued to the IERP members as a draft report, on Friday 12th October.
Comments received from the IERP were reviewed in a conference call held on 7th
November and a second draft then circulated. During this period a number of
questions were raised informally by Thames Water staff.
The IERP Chair formally issued the Final Draft Report ( reference - Second Draft
Report V2 03/12/12 ) to Thames Water on 6th December 2012 thereby enabling the
Company to consider its contents for the WRMP14 consultation exercise which
commences in March 2013.
Comments on the final draft, incorporating those received from Regulators
Stakeholders, were received from Thames Water on 24th January 2013
circulated to the IERP members. The IERP considered these comments and a
revision of the report was completed in February 2013. The final IERP report
formally issued to Thames Water on 15th March 2013.
15th March
2013
Page 9
and
and
final
was
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
4.
Findings
Even though IERP members brought a variety of international regulatory and
technical perspectives to bear on the Thames Water planned IPR challenge, there
was a strong consensus on the central conclusions of the review.
The principal findings of the IERP are presented structured around the two questions
posed in the Terms of Reference. The questions are considered in the order that they
were debated, with a summary of the relevant IERP conclusions presented first.
4.1
Question 1: “Is the Approach2 by which Thames
Water has Evaluated Technology Options for
“Planned” IPR Schemes in London Sufficiently
Robust?”
In summary - Within the context of international technology selection practices for
similar schemes, the IERP is satisfied that Thames Water has demonstrated a
systematic, logical and scientifically credible approach. However the IERP has made
observations with regard to (i) Thames Water’s approach concerning improved use of
existing literature, (ii) additional research on the MBR/GAC option and (iii) the
limitations imposed by not knowing the final reclaimed water re-introduction point.
The latter is particularly important in terms of receiving water quality and dilution.
4.1.1 Global Examples of Approaches to Technology Selection
The IERP experiences of how technology was chosen for specific “planned” IPR
schemes, or for other relevant treatment schemes, were compared. It is agreed that
a generic procedure was generally followed consisting of some or all of the following
steps:
• Literature reviews and reviews of good/best practice;
• Feasibility studies;
• Pilot trials generally – but not always; and
• Full scale implementation.
However there were some individual country-specific observations and a general
consensus that approaches have evolved over time with emerging issues and may
have led to variations in the approach outlined above. Potential risks to human health
from the consumption of drinking water supplies augmented with treated effluent
have always been a primary concern for any organisation undertaking a planned IPR
scheme. Information below includes how these concerns have been addressed in
schemes worldwide.
Australia
In Australia, there has been a focus on whether the chosen technology for “planned”
IPR would meet the Australian IPR (risk-based) water quality targets (Reference 3) ,
2
Note the IERP made the decision to use the term “approach” rather than the ToR term “process” to avoid later
confusion with treatment processes
15th March
2013
Page 10
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
and being also informed by international examples. Chemical quality has been
guided by the approach in the Australian Guidelines for Water Recycling while
microbiological quality is based on achieving log reduction targets. Published data
has been used to inform treatment process selection. The Australian Guidelines for
Water Recycling make reference to the point of application (re-introduction) and state
that while the aim is to provide water that is safe at the point of use, in many cases
proponents will elect to produce recycled water that is fit to drink before being added
to receiving waters and drinking water supplies. This decision is one for individual
proponents to make. However the two schemes that have been developed in
Australia are both designed to produce drinking water quality at the point of reintroduction. The Queensland Western Corridor scheme (reference 4) is a prime
Australian example that was often referenced during the workshop to help elucidate a
number of points. Piloting has not always been considered necessary in Australia,
and, for example was not undertaken for the Western Corridor Scheme, where the
design (UF/RO/AOP) was based on international best practice. Although the
Western Australia IPR scheme for aquifer recharge (Reference 5) included extensive
pilot testing of the chosen full-scale process it did not pilot a range of technology
options.
USA
“Planned” IPR has been evolving since the early 1970s in the USA, starting with work
on the iconic Water Factory 21 in Orange County California (Reference 6) where
researchers were recognised as “leaders” of the science. Another example is Denver
in the 1980s, where 10 years of pilot research was carried out, although a full-scale
plant was never built (Reference 7).The USA therefore probably has the longest
experience of the issues and there have been some “surprises” over this time period.
Technology choice has tended to be an evolution of previous work. Reverse Osmosis
is considered the “benchmark” technology, and a choice endorsed by the Regulators,
especially in California.
However it was noted that some reuse schemes in the US were not initially
implemented via a structured R&D approach with the aim of a “planned “IPR scheme,
but were driven by a need for upgraded “advanced” wastewater treatment to improve
river water quality, with only a later recognition of the value of high grade water that
could be considered for reuse purposes. This was the case in UOSA, Virginia
(Reference 8) in the 1980s and in Florida. It should be noted that in some instances,
subsequent testing throughout the full-scale plant has highlighted inadequacies in
water quality for reuse applications (particularly for pathogens in lieu of indicator
bacteria, such as enteric viruses & Giardia cysts) and the goals for treatment and
additional technology barriers then had to be brought into consideration for the
system. In Florida, smaller systems were no longer considered to be producing
effluent appropriate for reuse and in Virginia the application of ozone was
considered.
In Arizona the driver for (non-potable) reuse has been drought. Piloting prior to fullscale and working with universities and laboratories is the norm. In Arizona the
approach specifies a technology rather than providing an emphasis on testing.
Singapore
The “research” approach was used as a major pathway by Singapore in the initial
assessment and subsequent implementation of the NeWater facilities (Reference 9).
The objectives of the five years of R&D were focussed on achieving better than
drinking water quality. To date, monitoring of water quality is a major cornerstone for
15th March
2013
Page 11
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
demonstrating reliability of the technologies used and for providing assurances to the
public.
Europe
In Europe there are no EU-wide guidelines for reuse in general, let alone any that are
specific to “planned” IPR. In those EU countries that practise reuse it is usually for
non-potable applications (such as irrigation). The Torreele plant in the Belgium
(Reference 10) is the only classically recognised “planned” IPR scheme in Europe
(excluding the UK see below). The reclaimed water is used for aquifer recharge for
potable use and RO is used in order to comply with Belgian water quality regulations
for groundwater However a type of “planned” IPR is practised in Berlin, Germany
(Reference 11), where membrane filtered wastewater is discharged into surface
water lakes which artificially recharge aquifers, used as a source of drinking water,
through infiltration ponds and bank filtration.
UK
The major reference point for research in the UK, specifically related to “planned”
IPR, is the recommendations from an UKWIR (United Kingdom Water Industry
Research) project carried out in 2006 (Reference 12) The recommendation at that
time was that RO should be used as it was proven technology for removing, or
reducing in concentration, nearly all substances present, including “exotics”3 In
addition it was recommended that site–specific pilot trials be carried out to
demonstrate efficacy.
It was noted by the IERP that the Essex and Suffolk “planned” IPR scheme at
Langford (Reference 13) did not employ RO technology and was used extensively as
a reference example for this point at the Public Inquiry. The scheme includes the
following processes:
• High-rate lamella chemically assisted clarifier; (for phosphate removal);
• Submerged upflow filter (nitrifying & denitrifying) columns using methanol
as a carbon source; (for nitrate and ammonia removal);
• Option for dosing with powdered activated carbon (for removal of
oestrogenic compounds) ; and
• UV disinfection. (for pathogen removal).
The reclaimed water is re-introduced into the River Chelmer prior to re-abstraction for
drinking water treatment.
The IERP noted the different characteristics of this scheme compared to the
Deephams option, including the domestic nature of the rural sewerage catchment
area in the Essex and Suffolk case. Also the reclaimed water is much diluted in the
River Chelmer, a river which is less impacted by upstream discharges than the River
Lee. The IERP acknowledged that at the time of conception of the Essex and Suffolk
scheme in the early 1990s, the technology was considered suitable and the quality
drivers were primarily environmental. However, since that time, the knowledge and
approach to “planned” IPR has moved on considerably with, for example, the
publishing in the late 2000s of the Australian Guidelines in 2008 (Reference 3) and
new draft Californian regulations in 2011 (Reference 14). Membrane technology has
3
Exotics refers to emerging organic contaminants for which there are currently no standards, largely from domestic
sources and including, but not exclusively, pharmaceutical residues and endocrine disrupting substances
15th March
2013
Page 12
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
also advanced, with recent “planned” IPR schemes all using RO membranes (eg
Singapore, Western Australia, Orange County)
4.1.2 Thames Water’s Approach to Technology Selection
During discussions of Thames Water’s approach to technology selection a number of
key areas were raised which are summarised below. These areas and others were
expanded upon during consideration of process selection and more details can be
found in Section 4.2 .
Reference to Additional Literature
Thames Water’s approach to technology choice is considered consistent with
international examples in terms of initial literature review and piloting of an RO option
at Deephams. However it was felt that the reporting could be strengthened by making
more reference to specific literature on removal rates of contaminants of concern. A
large body of literature is available for many of the individual unit processes
evaluated; especially in the “grey” literature 4 .This is particularly relevant for the RO
and AOP option, which as has already been stated above, is well–trialed in
international schemes. Information on removal rates through MBRs is generally less
available as it is a more novel technology for IPR applications. Information from a
systematic literature review could therefore be very beneficial. However in general
the IERP considers that the strength of argument and the marshalling of external
information such as that from the Orange County scheme, WEF (Water Environment
Federation) reports, and other scientific work, such as the formulation of the
Australian Reuse Guidelines, would enhance support for the choice of an RO-based
treatment train at a site such as Deephams.
Period of Time & Scope of Research Evaluation of Old Ford (MBR/GAC) Plant
With respect to the Old Ford treatment plant the IERP considers that there has not
been sufficient time to gain robust data sets, in particular on the microbiological
performance of the treatment process, to support the Thames Water technology
evaluations. In addition, the scope of the research trials at Old Ford to date has not
been as extensive as the work at Deephams, and would benefit from further
consideration of the research objectives for IPR purposes.
Point of Re-introduction of Reclaimed Water & Relevance to Water Quality
Regulations
An issue that the IERP frequently came back to in the workshop was that the reintroduction point of the reclaimed water (i.e. river, reservoir or aquifer) has yet to be
decided. This is an important issue as the point of re-introduction will influence the
amount of dilution the reclaimed water is subject to before being re-abstracted and
treated at a given water treatment works.
Reclaimed water from a reuse plant located at Deephams could be returned to
augment potable supplies for treatment at Coppermills WTW (or Chingford WTW5) at
a number of locations. Firstly the reclaimed water could be introduced into the River
Lee upstream of the current abstraction point for the Coppermills reservoir system,
where it would mix with river water prior to abstraction. Historically this was
considered the least contentious option from a public perception perspective.
Alternatively the reclaimed water could be introduced directly into the Coppermills
4
Grey literature is defined as material that is not published through conventional channels. Typically covers commercial reports
or position statements..
5
Where Coppermills WTW is referred to in this report, it is recognised that Chingford WTW may also be relevant
15th March
2013
Page 13
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
reservoir systems, which would ensure that all of the resource was captured.
However it was noted that the Coppermills reservoir system which supplies raw water
to both two treatment works is complex, and issues of retention times and possible
short-circuiting would have to be considered, particularly during drought conditions.
(A simple schematic of the river and reservoir options is shown in Figure 6). It was
also noted that the reclaimed water could be used for aquifer recharge such as
NLARS (the North London Aquifer Recharge Scheme), although it is acknowledged
that the research on this option was not as well developed and is not currently being
pursued. ..
Figure 6
Simple Schematic of Possible Deephams IPR Re-introduction Points, 1) to River
Lee then Reservoir System and 2) Direct to Reservoir System
(Diagram Thames Water)
The debate on the point of introduction is key because it highlighted a crucial
question that the IERP was to return to frequently in the workshop, namely which of
the water quality regulations should the reclaimed water be targeting. Does the
reclaimed water quality need to meet the Environmental Water Quality goals, which
are enforced by the Environment Agency, or should the drinking water quality
standards in the Water Supply (Water Quality) Regulations be the target? This is
expanded upon later in this report as it also relates to the issues surrounding
“planned “versus “unplanned” indirect potable reuse.
15th March
2013
Page 14
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
4.2
Question 2: “How Appropriate is the Choice of
Technology for IPR Schemes in the Context of
Minimising Health Risks, the UK DWSP Approach,
TW’s Current Operating Circumstances and the
Scientific Foundations of the Work ?”
In considering Question 2 the IERP discussed Thames Water’s technology choice in
the context of the four criteria as per the Terms of Reference but in doing so
identified other key criteria which are also developed below.
4.2.1 Minimising Risks to Human Health
In summary the key view held by the IERP, with respect to human health risks, is
that there are significant advantages to a RO-based process train over an MBR/GAC
based process train, both in terms of conforming with a multiple barrier approach and
in terms of the overall effectiveness of the process, especially with regard to removal
of microbiological contaminants and emerging chemicals of concern.
The IERP believes that the Thames Water research approach to date has sufficiently
addressed the health risks from potential chemical contaminants of concern in an
IPR scheme, but demonstration of reduction in the microbiological risks needs more
attention. In this section the two treatment options (MF/RO/AOP – as piloted at
Deephams & MBR/GAC – as piloted at Old Ford ) are compared purely on their
technical merits. The issue of the ultimate quality required for the reclaimed water is
considered separately.
Microbiology & Health Risk
The IERP recommends that a gap analysis on the microbiological aspects of the
research should be undertaken by Thames Water. The use of indicator organisms
such as E.Coli to assess microbiological contaminant removal is considered to be
insufficiently precise, so the focus should be more on virus and parasite data. The
work should include sample distributions with a full range and time series of data.
Spiking trials with phage (such as MS2 and P22 which have been extensively used to
assess technology efficiency for removal of viruses) or using Molecular Polymerase
Chain Reaction (PCR) tests for viruses could be considered together with monitoring
of protozoa .
This is particularly relevant for the MBR/GAC option, the performance of which in this
context is not well documented in the literature. In Australia the Regulators are only
giving MBRs similar log reduction “credits” to activated sludge treatment6. By
contrast the efficacy of the MF/RO/AOP treatment train is well defined by other
studies and particularly recommended because it is a multi-barrier approach. GAC
does not provide an effective microbial barrier meaning that the MBR/GAC option
only provides a single barrier prior to disinfection. The data seen for Cryptosporidium
in the River Lee shows relatively low numbers present (compared to sewage) and the
reclaimed water from an MBR/GAC option would not match this low level.
The IERP notes that Cryptosporidium has historically been the reference pathogen.
This was because the oocysts of Cryptosporidium are very resistant to conventional
chlorination approaches and because of the severity of the disease. However more
6
David Cunliffe personal communication
15th March
2013
Page 15
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
recently Giardia has been considered a better indicator, primarily because of the
much higher and consistent concentrations of Giardia cysts in sewage.
The issues that Thames Water has encountered with respect to accessing UK
laboratories with the ability to analyse for viruses was noted and was identified as a
possible area for longer–term capacity building. In particular there are now molecular
techniques available for virus analysis including adenoviruses which are found at
high levels and norovirus, which can not be cultured. These molecular methods are
quantitative and can be used to evaluate removals of these bionano particles.
It was noted that log reductions are increasingly being used in international
guidelines for determining requirements for water recycling treatment options,
including “planned” indirect potable re-use (Australia, California)
Table 4 shows the IERP members considered opinion (based on their knowledge of
published and grey literature) of the indicative range of log reductions of
microrganisms for the elements of the two treatment trains considered
Table 4
Indicative Ranges of Validated Log Reductions of Viruses and Protozoa for
Different Treatment Steps – IERP View
Treatment Step
Log Reduction per
Treatment Step
(indicative ranges)
MF/RO/AOP
Sewage Treatment Works secondary treatment
0.5 - 1
MF (microfiltration) +
0.5* – 3**
RO (Reverse Osmosis)
1.5 – 2***
AOP (Advanced Oxidation Processes)
6****
MBR/GAC
MBR (membrane Bioreactor - full treatment on settled sewage)++
0.5 – 1.5***
GAC (Granular Activated Carbon)
0
+ note for MF - generally the higher log removals are associated with parasites and bacteria and the
lower levels of log removals are associated with viruses
* can achieve 1 full log with chlorine use, **higher log reductions (up to 4) usually associated with
ultrafiltration. Also removals above 2 log cannot be reliably assured by operational monitoring
techniques such as pressure decay tests, turbidity or particle counting
*** - low because of a lack of operational monitoring sensitivity
**** - note – maximum allowed in Draft Californian Groundwater Replenishment Regulations
Emerging Chemicals of Concern (Exotics) & Human Health Risk
The IERP believes that the range of chemical determinants that have been looked at
is comprehensive. Going forward, the IERP members believe that uncertainties and
emerging issues on contaminants of concern will continue to be a focus of attention.
Current examples were antibiotic residuals (resulting in concerns about antibiotic
resistance – although considered low compared to other sources of resistance) and
some pharmaceuticals (eg anticonvulsants like primidone or carbamazepine) as well
as residuals from recreational drugs (eg cocaine) that are already being detected in
15th March
2013
Page 16
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
drinking water. These are all on the DWI’s radar. Although there are currently no
numerical standards for such contaminants, standards may come into force in the
future.
The MF/RO/AOP option has demonstrated good removal of these types of
contaminants and the technology train is sufficiently robust to address future water
quality concerns. Although the data from the MBR/GAC option shows reduction in
chemical contaminants it is not as effective as the MF/RO/AOP treatment. Thus, in
terms of water quality outputs (regardless of whether it was considered necessary in
a UK context which is discussed elsewhere), the MBR/GAC option would require an
additional step, such as ozone or another advanced oxidation process to begin to
approach chemical removal rates achieved by the MF/RO/AOP option. Even then,
oxidation-resistant compounds such as PFCs and flame retardants may persist.
4.2.2 UK Drinking Water Safety Plans (DWSPs)
In summary, with respect to DWSPs, the IERP urges greater integration of the
Drinking Water Inspectorate & Environment Agency activities with respect to
“planned” IPR and support more specific consideration of sewage treatment works
and their catchments in DWSPs.
In England7, as well as mandatory targets for defined drinking water quality
parameters, there is also a requirement for a comprehensive risk assessment to be
carried out for each water treatment works as part of a Drinking Water Safety
Plan.(DWSP) (reference 15a). This requires the consideration of all potential hazards
and their mitigation that could arise in the catchment area of the source water, during
treatment, within the distribution system and within buildings up to the point of the
consumer’s cold water tap (see Figure 7). The approach is based on that advocated
by the World Health Organisation (Reference 16).
Thus the impact of an IPR
scheme on the receiving water would have to be taken into account in the DSWP of
any downstream water treatment works.
Figure 7
Drinking Water Safety Plans – Consider “Source” to “Customer Tap”
(diagram with thanks to Thames Water)
The IERP noted that in the UK, the Drinking Water Inspectorate is the main driver for
DWSPs and there seems to be no incentive for the Environment Agency to be
involved. Currently DWSPs are unlikely to look in detail at the risks from sewerage
catchments and the performance of Wastewater Treatment Works (WwTWs), relying
instead on compliance with effluent discharge consents. However these are likely to
7
Note - DWI and the EA have powers in England and Wales only and not the wider UK
15th March
2013
Page 17
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
cover only a very limited number of determinands (eg BOD, suspended solids,
phosphates and ammonia). There does not appear to be any regulatory requirement
to carry out an equivalent risk assessment/management/ mitigation process although
this would have to become a pre-requisite for any planned IPR scheme, as the
outcome could influence the technology choice.
The IERP noted that Thames Water carried out a detailed risk assessment of the
sewerage catchment and the individual elements of the MF/RO/AOP pilot plant as
part of the research phase of the IPR project at Deephams. The methodology was
based on the DWSP approach. It is understood that the Company has also
developed a specific, unique methodology to carry out risk assessments for every
WwTW catchment in relation to every downstream water intake, with the outcomes
being included in the associated DWSPs.
These approaches are commended by the IERP which also supports any initiatives
for risk assessments of sewerage catchments and the performance of WwTWs to be
considered in more detail in DWSPs. This is particularly relevant where there is a
significant element of “unplanned” IPR taking place, as in the case of the River Lee
upstream of the abstraction points to the Coppermills reservoir system. It is also
particularly relevant for WwTWs with industrial catchments, in respect of chemicals of
emerging concern and ‘exotics’.
It is noted that in Queensland (Australia) a full “Water Safety Plan” is undertaken for
any “planned” IPR scheme (ie the sewerage catchment, sewage treatment works and
the process elements of the IPR treatment plant) .This is then linked to the Drinking
Water Safety Plan for the Water Treatment Works that ultimately treats the receiving
water.
It is acknowledged that the introduction of “Planned” IPR may complicate the risk
assessment process and that any new approaches to integrate more detailed
upstream elements of river catchments (such as optimisation of each process within
a WwTW) within DWSPs would take time to implement.
4.2.3 Thames Water’s Operating Circumstances
In summary the IERP found the component of their work concerning Thames
Water’s operating circumstances to be the most complex. The IERP recommends a
de-coupling approach as adopted elsewhere, whereby any new “planned” IPR
schemes are considered differently to existing “unplanned” circumstances, in terms
of the reclaimed water meeting drinking water equivalent quality targets. However the
IERP felt that this was a decision for Thames Water to make with reference to which
water quality goals they wish to pursue within the UK Regulatory and political
context. The Company should then engage with a wider, external audience.
Furthermore the IERP concluded that, as Thames Water are currently the most
active utility explorer of reuse options in the UK,t is likely to be seen a leader in this
area in a setting not helped by a perceived regulatory vacuum. A key decision for the
Company is what risk it is prepared to take in anticipating future regulatory goals &
capacity–building. In addition, the IERP feels that more focus should be given to
operational issues and monitoring for a full-scale IPR implementation. In the case of
Deephams, this should include current River Lee and Coppermills reservoirs water
quality, the implications of dilution factors, the impact of drought conditions and
intermittent use of an IPR scheme, and the re-introduction points for the reclaimed
water, including the possibility (although likely to be contentious) of “direct” potable
reuse (defined as introducing the reclaimed water at the inlet to the water treatment
15th March
2013
Page 18
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
works). International experience has shown that pressure groups can derail
implementation of schemes and communications and interaction with the media,
customers and the public at large as well as public perception issues have to be
carefully considered.
The subject of Thames Water’s specific operating circumstances and the current UK
regulatory regime attracted the most time and debate amongst the IERP members
during the workshop and was expanded to include discussion of the regulatory
regime and the current situation with regards to “unplanned” IPR.
Unplanned v Planned IPR – the Decoupling Debate
In the international experiences brought to the workshop by the IERP, it was noted
that there has been invariably been a definite decision to “de-couple” the approach to
IPR on the basis of whether it is “planned” or “unplanned”. In the USA and Australia,
“planned” IPR is most advanced. In the USA a substantial amount of “unplanned”
IPR takes place, where, through historic legacy, wastewater treatment works
discharge treated effluent to rivers from which abstraction downstream takes place
for treatment for drinking water. Cities along the Mississippi River are examples of
this, as is the city of San Diego where the water treatment works is influenced by
upstream discharges as it takes water from the Colorado River and State Water
project (water coming from the Sacramento and San Joaquin River Delta). In
Australia county towns such as Dalby present similar circumstances, although it was
noted that the main cities in Australia tend to be on the coast and these populations
are therefore less subject to voluminous upstream discharges.
In the UK
“unplanned” IPR is common as a result of the way centres of population have
developed over time.
In the USA and Australia the stance taken has been to largely “de-couple” or treat the
two scenarios (ie unplanned & planned IPR) differently. This has been achieved by
accepting that the historic legacy “unplanned” situation is covered by existing
regulatory requirements, but imposing a specific set of new water quality criteria for
wastewater effluent that is going to be pro-actively managed and “planned” to
augment drinking water sources. Thus the new IPR water quality criteria for the
treated wastewater effluent are more akin to drinking water standards (eg the USA
California groundwater recharge regulations, the Australian IPR Guidelines and State
Regulations and the Singaporean IPR quality goals) than environmental standards
for receiving waters. This obviously has a significant influence on the technology
chosen.
The decision to de-couple is perceived by the IERP to be based on a range of
reasons arising from differences between planned and unplanned use. These include
that design and monitoring of planned IPR schemes has to some extent been driven
by an increase in knowledge and scientific experience of water quality challenges in
more recent years and hence the desire to address concerns from new and emerging
hazards such as pharmaceuticals, hormones, personal care products, endocrine
disrupting chemicals etc as well as microbial pathogens. However, issues associated
with public perception and reassurance has also played a role. Imposition of
requirements applied to planned IPR to traditional discharges would be expensive
and in most cases unreasonable. The need to upgrade existing facilities should be
addressed separately using risk based approaches.
In relation to de-coupling, the IERP also highlight another way of distinguishing
between planned and unplanned potable reuse projects - through the matter of
“intent”. With unplanned potable reuse a discharger is simply trying to comply with
15th March
2013
Page 19
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
environmental requirements for reintroducing treated effluent back to the
environment. The downstream water users who abstract water for drinking water
purposes are not formally dependent on the discharge to supplement water supplies.
There is no intent by the discharger to meet water supply needs and while
dependency on the water course for water supply is implicit there is normally no
explicit dependency on discharges to the water course. Using a Californian example:
- Orange County is dependent on discharges to the Santa Ana River, which make up
most of the baseflow in the river, but the discharges are not considered planned
indirect potable reuse and are not regulated as such. The intent of the dischargers is
not to provide a water supply, even though the downstream users are dependent on
that flow for groundwater recharge. The river discharges are treated very differently
to the Groundwater Replenishment System (GWRS) which was constructed and is
operated with the intent to provide a new water supply source for groundwater
recharge, using waters that would otherwise be discharged to the ocean.
The IERP also identified other issues associated with decoupling from their
experiences including:
Uncertainties relating to the contribution and impact of traditional discharges
on source water quality in terms of pathogen and chemical concentrations at
inputs to reservoirs and inputs to water treatment plants.

Differences in Regulatory regimes, with traditional discharges to surface
waters being assessed more on impacts to receiving waters by environment
agencies whereas health agencies and drinking water regulators play a
stronger role in assessing planned IPR

Discharge of treated sewage into sources of drinking water supplies while a
practical reality can be seen as an undesirable source of chemical and
microbial hazards. In contrast correctly planned IPR can be seen as a
beneficial source of water to augment drinking water supplies
The IERP concludes that, as there are currently no equivalent EU or UK regulations
or guidance for IPR water quality, an internal Thames Water debate is needed to
decide on a stance with regard to de-coupling and the target water quality. There are
two potential approaches, to either aim for drinking water quality / IPR-quality water (
as per international examples) at the IPR treatment plant, which is the approach
adopted in international practice and advised by the IERP, or aim for “good” quality
reclaimed water and factor in the treatment at the WTWs. The former is important if
the recycled water is intended for aquifer recharge, as in Belgium, whereas the latter
relies on the most appropriate technology being applied at each water treatment
works in order to meet the regulatory drinking water standards.
Thames Water is seen amongst the UK water utilities as being very active in water
reuse research and demonstration projects. In the early 2000s the Company
designed and ran Europe’s largest in-building recycling facility at the Millennium
Dome, and throughout that decade and to date, both with their international work and
projects such as BedZED and the Olympic Park it was recognised as being at the
forefront of water reuse in the UK. The Company therefore has a key interest in the
required water quality goals. The IERP recommends that, following their internal
decisions, Thames Water should bring the issue of standards to the attention of a
wider, external audience.
15th March
2013
Page 20
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
Planned IPR – the UK Regulatory Environment
The IERP notes that “planned” IPR straddles the remits of a number of different UK
regulatory bodies and the IERP feels it would be beneficial if a more cohesive
dialogue was possible. In terms of IPR technology choice, the EA would likely confine
its view to the impact of the reclaimed water on the receiving water course and would
not have the same concerns as the DWI regarding the ultimate impact on human
health from drinking water. The EA is responding to the Water Framework Directive
(WFD) as one of the main drivers - focusing on lowering nitrogen and phosphorous to
reduce eutrophication and achieve good chemical and ecological river status.
However it was noted that the Priority Substances Directive (a “daughter” directive of
the WFD) is being developed, which will list a number of substances that require
focus of attention. Many of these will probably be emerging chemicals of concern or
exotics. Other bodies, such as Natural England, may also have a view on “planned”
IPR.
Interestingly, in Australia the environmental regulators generally prefer RO for
“planned” IPR applications, as it takes out more undesirable contaminants.. Similarly
in California, the City of San Diego is proposing to use MF/RO/AOP for reservoir
augmentation with recycled water to meet the treatment and quality expectations of
environmental and drinking water regulators, and to address the concerns of elected
officials and an increasingly engaged public.
An important consideration is to what extent Thames Water wishes to manage the
risk of anticipating longer term issues. The view of the IERP, particularly those
members with an EU/UK perspective, was that over time there is going to be a move
towards more stringent control of “exotics” which will impact on WwTW consents in
any case. Similarly the emerging contaminants of concern in drinking water, such as
pharmaceuticals, are likely to be targeted. Currently the wording of the Water Supply
(Water Quality) Regulations (Regulation 4 “wholesomeness”) is non-specific in
relation to “exotics”, with for example a reference in Section 4 paragraph 2 with the
requirement that “the water does not contain:
(i) any micro-organism (other than a parameter listed in Schedule 1) or parasite; or
(ii) any substance (other than a parameter listed in Schedule 1),
at a concentration or value which would constitute a potential danger to human
health;”(our highlight)
However it was noted that the DWI has already issued guidance on a number of
emerging contaminants of concern8. In terms of financial regulation and risk, there
was an acknowledgement that the OFWAT five year funding cycle was not conducive
to longer term planning.
With international examples, changes in the political environment have often led to a
“stop/go” situation with respect to “planned” IPR plants, with the immediacy of
drought events also having a bearing on levels of commitment. This has been the
case with the Australian Western Corridor scheme, with operating rules being
changed following the end of drought conditions to delay the likelihood of recycled
water being added to the drinking water supply. The possibility of moth-balling the
plant is now being considered to reduce costs. A similarly punctuated process has
been seen in San Diego. Such inconsistent commitment is not helpful to maintain
the momentum of “planned” IPR schemes which require long-term investment and
engagement to mature.
8
Eg PFOS and PFOA; NDMA and monitoring for pharmaceuticals in raw water
15th March
2013
Page 21
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
The IERP recognises that Thames Water is developing planned IPR proposals in
what might be termed a “regulatory vacuum”. This is due to a lack of governance
ownership for the mechanics of “planned” IPR schemes from the UK Regulators, who
do not appear to have directly addressed the issues around reuse and the
requirements related to “planned” IPR. There is also a perceived lack of political will
in the UK & EU to address the complex issues of “planned” IPR, not least because of
the multiple drivers (e.g. environmental & drinking water quality ).
The IERP supports an approach whereby Thames Water actively draws this issue to
the attention of the wider regulatory audience where the debate should be
undertaken.
Operational Issues
A number of operational issues were discussed in the workshop, with the focus being
mainly on the Deephams IPR scheme and the work at Old Ford. However the IERP
was also shown comparative operational data from two other full-scale sites with
lesser (to RO) forms of treatment, namely the BedZED Water Recycling Plant (a
small scale award winning sustainable development, treating raw sewage for non
potable use) and Swindon WwTW, which has disc filters followed by GAC for the
removal of micro-contaminants. This work was presented in the IERP Briefing Pack
2 - IPR Technology Study Report August 2012 (see Appendix C)
The comments below specifically relate to the promotion of a “planned” IPR scheme
at Deephams .
The River Lee already contains a significant portion of treated sewage
effluent, even in average flow conditions (approx 40% - EA 1997 figures), and
this figure is likely to be much higher under drought conditions. Rye Meads
and other WwTWs contribute to this as “unplanned“ IPR. Hence there is
already a significant WwTW burden on the river and Thames Water needs to
be able to demonstrate it would not be increasing the risk to public health with
any proposed “planned” IPR scheme at Deephams (for example the
Cryptosporidium burden in the River Lee). Additionally the fact that
Deephams WwTW is currently being upgraded will impact the debate. One
argument for the re-introduction of highly treated reclaimed water directly to
the Coppermills reservoirs is that discharge to river could be seen as “wasting
or contaminating the high-quality reclaimed water”. Alternatively discharge to
river could be considered as improving the current river water quality. It was
also noted by the IERP, in relation to re-introduction points, that in certain
circumstances, post-treatment (eg re-hardening) may have to be considered.
Coppermills9 treated water quality:- There is a need for Thames Water to
demonstrate that having RO at the IPR stage will ensure that there is no
further deterioration in the raw water quality at Coppermills WTWsin terms of
emerging chemicals of concern and ‘exotics’. More attention should be given
to the data from the existing Coppermills plant monitoring in relation to
decisions around a “planned” IPR option, including the monitoring of raw
water quality under Regulation 16A of the Water Supply (Water Quality)
Regulations 2000, as amended in 2007 (Reference 15b)). As the DWI shares
this data with the EA, it effectively becomes a Water Framework Directive
(WFD) driver. Monitoring of the treated water for emerging chemicals of
9
Where Coppermills WTW is referred to in this report , it is recognised that Chingford WTW may also be relevant
15th March
2013
Page 22
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
concern and “exotics” should also be considered. If a full-scale “planned” IPR
scheme came to fruition then better monitoring of all aspects of the scheme,
(ie WwTW catchments, WwTW, IPR plant, river, reservoirs and WTWs ) may
become necessary.
Intermittent operation (of the IPR plant) can be an issue for many types of
treatment process. Some processes do not respond well to being brought in
and out of service, as would be the case when a plant is designated for
service in drought periods only. In addition, the environmental conditions
would be more challenging in drought conditions, as the receiving water
courses are likely to have minimal flow. Depending on the point of reintroduction, this could result in less dilution of the reclaimed water and
increase the proportion of reclaimed water entering the downstream WTWs.
Planned Direct Potable Reuse? The issue of the appropriate re-introduction
point for the reclaimed water was again discussed, but this time in relation to
“direct” potable reuse. There is a move in the USA to re-consider this once
inconceivable approach, mainly not considered previously due to fears of
negative public response and uncertainty. (The direct potable reuse system in
Namibia is as exception, being the only one of its kind in the world) The very
high quality of RO/AOP treated reclaimed water will deteriorate significantly
when it is returned through an environmental barrier to ambient waters of
poorer quality, such as a river or reservoir, a situation which is avoided with
“direct” reuse. A case could be made for the direct introduction of reclaimed
water from a potential “planned” IPR scheme at Deephams to the Coppermills
WTW inlet, instead of discharge to a river or reservoir, as this would prevent
the deterioration of a very high quality water resource. However it would still
be a contentious option, mainly because the “time” barrier is lost and it is
difficult to eliminate all risk from potential human error. The Australian
Guidelines state that direct use presents substantial challenges. Other water
quality experts, for example Don Bursill in Australia, have expressed concern
about the risk from operator incompetence or human error if potable reuse is
contemplated, and this would be magnified even more for direct potable
reuse10.
Capacity building:- The IERP feels that it is important to stress the wider and
longer-term benefits when promoting any “planned” IPR scheme and not just
the water resources deficit driver. The ability to use treated sewage effluent in
such a way should be considered as a step on the continuum of capacity
building towards holistic water resources management. Maintaining a
research element is important for this and links back to Thames Water’s
views and aspirations in this regard. Promotion and retention of
competencies, skills, and understandings relevant to “planned” IPR within
Thames should be considered, as should the next steps with the pilot plant
facilities at Deephams. With regard to the facilities at Old Ford, if a
MBR/GAC option for “planned” IPR is still going to be pursued by Thames
Water then the objectives of the research and the research plan should be
better defined.
Sites for full- scale IPR plants
10
David Cunliffe personal communication
15th March
2013
Page 23
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
The IERP focussed on the Deephams scheme as this is the most advanced
in terms of pilot plant trials. However it was noted that a number of other
“planned” IPR schemes are being considered. These additional sites included
Hogsmill STW, as in the WRMP09, and Beckton STWs and Abbey Mills
pumping station which were being considered as options within the draft
discussions for WRMP14.
As an additional activity following the workshop, the IERP was specifically
asked to comment on the proposed WRMP09 Hogsmill scheme as this had
not been covered in the workshop discussions. The IERP members were sent
summary briefing material on the Hogsmill scheme which was then discussed
at a telephone conference call on 7th November 2012. Following this
discussion, the view of the IERP was that, although the same general
approach they had advocated for Deephams was applicable to the proposed
Hogsmill “planned” IPR scheme (and other potential schemes), each specific
scheme would have to be assessed individually. It was recommended that a
drinking water safety plan approach be part of this assessment, namely a risk
assessment to identify potential hazards from the WwTW’s catchment,
possible impact of the reclaimed water on the receiving water and the likely
drinking water abstraction point. The levels of mitigation required would then
feed into the choice of technology to be used.
Pressure Groups and Public Perception
Public perception was not part of the IERP’s terms of reference. However it is
a significant aspect of any “planned” IPR scheme and could not be completely
ignored in the discussions.
Pressure Groups:- The IERP noted that the pressure groups which are
currently engaged with the “planned” IPR debate in the Thames Water
context, are very different to those that had been encountered in other
international “planned” IPR schemes, in that they are promoting the
introduction of “planned” IPR (albeit challenging the RO technology choice)
Typically international pressure groups have campaigned against such
schemes eg CADS (Citizens Against Drinking Sewage) in Australia and
similar groups in the San Fernando Valley of Los Angeles and in San Diego..
Although in Australia the environmental benefits of “planned” IPR schemes
have been recognised by some and, in the USA, environmental groups such
as the Sierra Club and Coast Keepers have been among the first to embrace
“planned” IPR proposals. The IERP generally felt that the UK pressure
group’s focus on “lesser” treatment technologies for “planned” IPR and the
Public Inquiry Inspector’s directions to investigate these, had interrupted the
substantially researched and preferred route of “planned” IPR by Thames
Water.
Media: - From international and UK (Essex & Suffolk) examples it is clear that
the media can be very influential in any IPR debate and, as such, the media
should be treated as any other stakeholder. Tone as much as content is
important in any media reporting.
Understanding of Risk:The average water consumer, unlike the
Regulators, does not fully understand the meaning of risk and risk
assessment data, but looks for “comfort” signals and assurances. In Australia
the Regulators use the concept of DALYs (Disability-Adjusted Life Years) as
the end point for achieving safety. The USEPA Regulators have articulated a
15th March
2013
Page 24
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
10-4 goal as an annual risk of probability of infection for drinking water, as a
guideline. (<1 infection in 10,000 with 2 litres of water consumption per day
for 365 days). Both Australian and US Regulators use Quantitative Microbial
Risk Assessment (QMRA) which is fairly well understood (but not well
explained), to asses health risks when using reclaimed water. There is
generally no equivalent approach in Europe and the UK.
Customers often challenge technology choice and what they perceive is an
unreasonable or inappropriate risk, although their reasoning may well be
influenced by media coverage. Whilst they want assurances about safety they
could also be concerned that utilities are not using “gold plated” options
because this obviously affects their water bills. Customers typically don’t have
an understanding of the complexities of why costs increase. Thus in the UK,
media stories such as those referring to water prices increasing to pay
excessive remuneration to the utility directors, have tended to influence
customer opinions. The UK context is slightly different to the US, where
scheme operators are often one step removed from the customer eg OCWD
(Orange County Water District) which uses recycled water to replenish
groundwater that is in turn pumped and delivered to customers by retail water
supply agencies. On this basis the IERP feels that Thames Water should
have an advantage in implementing “planned” IPR over some of the
international examples as it is responsible for the provision of both drinking
water and sewage treatment, (similar to the situation in Singapore and
Australia) but will still have to work closely with the media and public.
4.2.4 Scientific Foundations
In summary the IERP felt, with respect to the scientific foundations, that the case for
a multi-barrier, RO approach is well established internationally. Thames Water has
not sufficiently demonstrated the efficacy of the MBR/GAC option from its Old Ford
trials or through reference to the literature, and the energy and cost–comparisons
also require more data. If the MBR option were to be pursued, even with further trials
as recommended, Thames Water would probably have to defend it in isolation, as it
is out of step with current international practice.
Many of the issues around the scientific foundation of the IPR technology choice
have been covered in the previous report sections but some key areas and some
additional points are emphasised by the IERP as follows:Current Status of the Science
The evolution of technology and the scientific foundations are well established for
planned IPR so, in terms of technology choice, Thames Water must consider the
situation as it currently stands. Water Factory 21 and Stanford University have looked
at technology options over the longest period of time, and compared GAC and RO at
early stages of their work (1970s and 1980s). There are some key and influential
world-recognised experts in this field. Shane Snyder, David Sedlak and Jorg Drewes
are among the leaders in investigating toxicological relevance of trace organics and
identifying emerging contaminants of concern and were on the committee that
prepared the 2012 National Research Council (US) report on Water Reuse potential
for expanding the Nation’s water supply through reuse of municipal wastewater.
(Reference 17)
The late Professor Dan Okun (US) was an internationally renowned environmental
engineer who was a proponent of non-potable reuse (Reference 18) He had
15th March
2013
Page 25
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
espoused early on in his 60 year career that the threat from “unknown unknowns”
required that the precautionary principle be used. Although much more is known
today about the types of contaminants, their concentrations and health risks,
uncertainties remain and thus there is interest in maintaining a multiple barrier
approach and selecting the best barriers to many contaminants. In this regard Mike
McGuire, Perry McCarty and their colleagues (US) recommended the addition of
advanced oxidation to RO treatment to address the threat of unknown
unknowns.(reference 19). The November 2011 draft California Department of Public
Health Regulations for Groundwater Replenishment Reuse include the requirement
for both reverse osmosis and AOP treatment as part of Full Advanced Treatment
(FAT) for injection of recycled water into drinking water aquifers.
The requirement for effective barriers to protect public health is unquestioned and the
MF/RO/AOP multi-barrier technology choice is recognised as sound. In addition the
chlorine ( to control biofouling) typically used during the MF and RO process train
provides yet an another barrier.
As MBR/GAC comprises only two barriers for chemical contaminants and one barrier
for microbial pathogens prior to disinfection, the IERP believes that more would have
to be done to demonstrate the efficacy of this treatment option. As discussed in
Section 4.2.1, the addition of an extra barrier such as advanced oxidation should be
considered The addition of an extra barrier would be consistent with international IPR
schemes that use GAC in multi-barrier approaches as documented in the 2012 NRC
report already mentioned (see Reference 17) The effective lifetime of the GAC needs
to be demonstrated as do the procedures for monitoring and identifying when the
carbon is exhausted. The microbiology research, was identified by the IERP as
needing strengthening. This could include spiking trials with phage or spores ( eg
bacillus or sulphate reducing bacterial spores), monitoring of protozoa, and the use of
molecular tools such as polymerise chain reaction (PCR) to monitor viruses and
other unique targets to evaluate the efficacy of each treatment barrier. There is
published work in the area of spiking trials and details are available in the literature.
Manufacturers log reduction claims are also available and should be referenced.
This highlights again the importance of more reference to the literature and
accessing any other recent reviews in helping Thames Water demonstrate
equivalences in treatment options. However knowing the literature is not the same as
demonstrating that Thames Water can operate such a plant and show reliability
through an improved and sufficient monitoring plan.
The IERP members have provided additional examples (over those discussed
previously) of schemes and projects they knew of which may be useful to Thames
Water. These include work done on River Trent which looked at RO versus
conventional WTW (Reference 20) and the Virginia Loudoun County MBR plant
(reference 21) which although for non-potable uses also included GAC & UV. In
addition, a recent paper published in Australia (Reference 22) that presented views
on a non-RO approach was discussed in detail. The IERP concluded that the
analysis in the paper was incomplete, particularly in relation to microbiological
quality-.
As mentioned previously, a 10-4 annual risk for microbial pathogens has been
suggested as acceptable for drinking water in the USA and codified in law in the
Netherlands.
This approximately equates to a 10 -6 daily risk and a 10-9 daily
estimate for the DALY metric that Australia uses. Through an adequate monitoring
programme these levels of safety can be shown by i) understanding concentrations
15th March
2013
Page 26
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
and ranges of virus and parasitic pathogens in the effluent entering the reclaimed
water facility; ii.) demonstrating the log removals via the multiple barriers and iii)
calculating low levels of probabilities using dose-response models and QMRA
approaches
Technical Questions Specific to TW Research Trials
Old Ford Research Plan: - The IERP has some specific thoughts on the
Thames Water research trials, particularly around the Old Ford Plant. The
IERP feel that a goal and conclusion with respect to IPR needs to be
strengthened for the Old Ford IPR work, probably because it had become an
“add-on” to the original Old Ford objectives which were for non-potable uses.
If looking for equivalence with the Deephams pilot plant, for “planned” IPR
uses, then advanced oxidation should be trialed at Old Ford. There was also
a research question as to what point in the treatment train it should be
inserted. There are unanswered questions about how the MBR option would
work on WwTW final effluent as it had currently only been trialed on settled
sewage. This also raises questions about the configuration in which MBR
would be used at full scale. It is important to adopt a rigorous approach to the
science and the IERP feel that there are gaps in the research data. Overall
the IERP felt that if the MBR/GAC was being considered as a feasible option
Thames Water would have to defend it in isolation as there are no
international examples of this technology for planned IPR.
Cost & Energy Consideration An energy efficient technology choice may
not generate the same outcome as the technical choice in respect of water
quality. The carbon in the MBR/GAC has a cost which needs to be brought
into the equation. This cost is currently unknown as the regeneration times
are yet to be established. If the cost of carbon and the addition of an AOP
step has to be considered, then the cost of the MBR option may converge
with the RO option. A whole life cycle cost assessment needs to be
undertaken and reliability of the process streams also considered. With
respect to the promotability of any planned IPR scheme, there may be cost
savings with an RO option, in that a “lesser” option might be less acceptable
to the public and hence increase the budget for consultation and promotion of
the option.
Whilst difficult to predict with any degree of certainty, consideration should
also be given not only to the ongoing development of new and lower energy
membranes and the associated potential savings but also other new and
innovative technologies that may be available in the future.
4.3
Comments Received from Thames Water
4.3.1 During Preparation of First and Second Drafts
Following the workshop, and during the first drafting stage of this report (7 – 20 Nov),
additional information and questions were received informally from Thames Water
and considered by the IERP. However the IERP feel that the additional material
provided does not change the opinions they reached at the workshop. Nevertheless
the IERP welcomed the opportunity to assist Thames Water and comment more
specifically on the material provided, and this feedback is given in Annex G.
15th March
2013
Page 27
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
It should be noted that under the ToR the draft report of the IERP is to be formally
issued to Thames Water at the start of December 2012. Consolidated comments
back from Thames Water will be considered and incorporated as the IERP feel
appropriate into their Final Report to be formally issued by 1st March 2013.
4.3.2
Comments received following circulation of the Second Draft
The Second Draft Report (version 2) was issued to Thames Water on 5th December
2012. It was circulated internally within Thames Water and also sent to relevant
Regulators and Stakeholders for comment. The latter comprised DWI, Ofwat, EA,
Defra and CCWater Thames Water provided a consolidation response with all
comments back to the IERP Chair on 24 January 2013.
The IERP welcomed and considered the comments received. Additional text was
added where points of clarity were identified as an issue. Responses were provided
directly to Thames Water on specific comments that were not considered relevant or
appropriate for this report.
Overall the IERP felt that the comments received did not cause them to alter their
expert opinions as expressed in the report with regard to the Terms of Reference on
which they were engaged.
15th March
2013
Page 28
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
5.
Conclusions and Recommendations
The Independent Expert Review Panel (IERP) has considered the information
provided by Thames Water and debated the Terms of Reference questions over the
workshop period and is in agreement over the conclusions and recommendations
which are as follows:
5.1
Conclusions
The overarching task posed to the IERP was:
“To consider outputs of relevance from Thames Water research pilot trials and
other available information and advise on the suitability of the approach to
technology selection and the selected technology for full-scale planned
Indirect Potable Reuse Schemes in London”
The IERP concludes the following in respect of the specific questions posed:Thames Water’s approach to technology selection:- The IERP considers that
Thames Water has demonstrated a systematic, logical and scientifically credible
approach to technology choice for planned Indirect Potable Reuse (IPR), which is
comparable with key international examples of implementation of full-scale planned
IPR schemes. Notwithstanding, the IERP has some observations with regard to
Thames Water’s approach concerning improved referencing to existing literature, the
requirement for more research work on the MBR/GAC option and the limitations
imposed by the lack of decision on the reclaimed water re-introduction point.
Health risks: - The IERP believes that solely with respect to health risks, there are
significant advantages in the RO/AOP based process train over an MBR/GAC based
process train, both in terms of multiple barriers and effectiveness of the process,
especially in terms of the removal of microbiological contaminants.
Drinking Water Safety Plans (DWSPs):- The view held by the IERP is that
enhanced cooperation between and coordination of the respective roles Drinking
Water Inspectorate (DWI) & Environment Agency (EA) with respect to DWSPs in the
context of “planned” IPR would be beneficial, and they support more specific
consideration of sewage treatment works (STWs) and their catchments as a source
of hazard and the first points of control within DWSPs.
Thames Water’s Operational Circumstances: - The IERP acknowledges that this
is a complex area, particularly as it perceives a regulatory “vacuum” in the area of
effluent reuse in the UK. The IERP recommends a de-coupling approach, as adopted
elsewhere, whereby new “planned” IPR schemes are considered separately to the
current “unplanned” scenario, with the aim of meeting drinking-water-equivalent
quality targets The IERP recognises that Thames Water have to work within the UK
Regulatory and political context. However as Thames Water is currently the most
active utility explorer of reuse options in the UK it is seen as the leader in this area
Therefore it should make an internal decision on the way forward as this affects
which IPR water quality goals to pursue. It is also integral to what risks the Company
is prepared to take in anticipating future regulatory goals, addressing longer term
challenges and capacity–building. Thames Water should then continue to engage
15th March
2013
Page 29
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
with a wider external, regulatory audience. The IERP noted that, in the absence of
any European or UK guidelines on planned IRP, Thames Water adopted international
best practice in designing the pilot plant at Deephams. Given the increasing interest
being shown in “planned” IRP, the IERP considers that it would be beneficial if the
UK water quality regulators could take a more proactive approach to issuing
guidance on the water quality issues associated with “planned” IRP and the levels of
treatment required for the reclaimed water.
With respect to implementation of full-scale IPR schemes, the IERP feels that more
focus should be given to current and future operational and monitoring issues eg the
current quality of the receiving water and the treated water quality at downstream
WTWs, the impact of drought conditions and intermittent use of an IPR scheme, and
the re-introduction points for the reclaimed water and subsequent dilution factors,
including the possibility (although contentious) of “direct” potable reuse. It was noted
that pressure groups can derail the substantially researched and preferred
implementation of schemes, and the media and customer public perception have to
be carefully addressed.
The IERP focussed on the Deephams scheme as this is the most advanced in terms
of pilot plant trials. However it was noted that a number of other planned IPR
schemes are being considered and the IERP believes that, although the same
general approach they had advocated for Deephams was applicable, each scheme
would have to be assessed individually in terms of levels of risk and technology
choice. It is recommended that a drinking water safety plan approach forms part of
this assessment.
Scientific foundations: - the IERP believes that the case for a multi-barrier RObased approach is well established internationally through high-quality science and
operational practice. The IERP feels that Thames Water has not yet sufficiently
demonstrated the efficacy of the alternative MBR/GAC option, either from the Old
Ford trials or by reference to the literature; and the energy and cost–comparisons
also required more data. If the MBR/GAC option were to be pursued, even with
further trials as recommended, Thames Water would currently have to defend the
technology choice in isolation, as it is out of step with international practice.
5.2
Recommendations
The IERP make the following recommendations for Thames Water to consider
Research Trials
1. Conduct systematic literature reviews to strengthen the evidence base of the IPR
research trials to date. This is particularly important for the MBR/GAC technology
option at Old Ford.
2. Implement a more rigorous approach to sampling and testing for microbiological
contaminates at the two research sites.
3. Define in more detail the goals and conclusions of the research trials, particularly
for Old Ford.
Considerations for Full-scale
4. Come to a conclusion on where reclaimed water is to be re-introduced (river,
reservoir, direct to WTWs, or aquifer). The quality of the receiving water and the
level of dilution will be paramount to this decision. In the case of Deephams this
15th March
2013
Page 30
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
5.
6.
7.
8.
9.
may require more work on the complex hydraulic system of the River Lee and
Coppermills / Chingford storage reservoir systems.
Enhance monitoring activities to better understand i) natural and engineered
water quality (eg in the case of Deephams: Rye Meads discharge, River Lee,
Coppermills and Chingford WTWs inlets and treated water entering supply, ii)
current operational practice in respect to future planned IPR (eg in the case of
Deephams: Rye Meads WwTW and Coppermills /Chingford WTWs performance)
and iii) the extent of current unplanned reuse
Evaluate the challenges of future IPR schemes (eg during periods of drought or
intermittent operational scenarios)
Review the internal strategy regarding the approach to IPR water quality goals
and the de-coupling arguments and consider how the “planned” IPR strategy can
be strengthened through engagement with regulators and other stakeholders
Review the longer term requirements for skills and competency capacity-building,
for “planned” IPR scheme design and operation, for example in virus analysis
Ensure full consideration of wastewater catchments and WwTWs for any planned
IPR schemes within DWSPs.
15th March
2013
Page 31
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
References
6.
No
Concerning
Source
1
Old Ford Water Recycling
Plant
http://learninglegacy.london2012.com/publications/theold-ford-water-recycling-plant-and-non-potablewater.php
2
Deephams Pilot Plant
IWA Reuse Conference, Brisbane, September 2009 –
abstract A holistic approach to explore the potential of
planned Indirect Potable Reuse for London. S Hills et al
3
Australian IPR Regulations
Australian Guidelines for Water Recycling :managing
Health and Environmental Risks (Phase 2)
Augmentation of Drinking Water Supplies 2008
4
Queensland Western
Corridor Scheme
http://www.qwc.qld.gov.au/security/supplyinitiatives.htm
l
5
Western Australia IPR
aquifer recharge scheme
http://www.watercorporation.com.au/g/gwr.cfm
6
Orange County Scheme
http://www.gwrsystem.com
7
Denver research
Using Reclaimed Water to Augment Potable Water
Resources WEF AWWA special publication 1998 p
319 - 337
8
UOSA scheme
Reduction in Enteric Microorganisms at the Upper
Occoquan Sewage Authority Water reclamation plant,
Rose et al. Water Environment Research, Vol. 73, No.
6 (Nov. - Dec., 2001), pp. 711-720
9
New Water Scheme
www.pub.gov.sg/
10
Torreele Plant , Belgium
Sustainable groundwater management using reclaimed
water, the Torreele/St-André case in Flanders, Belgium.
Emmanuel Van Houtte and Johan Verbauwhede.
Journal of Water Supply: Research and Technology,
AQUA Vol 61 No 8 pp 473–483 © IWA Publishing 2012
doi:10.2166/aqua.2012.057. .
11
Berlin Scheme, Germany
Wastewater Re-use and Groundwater Quality (Proceedings
of symposium IÎS04 held during IIJGCJ2003 at Sapporo. July
2003 Al IS Publ. 285. 2004. Conservation of water resources
in Berlin, Germany, through different re-use of water. Birgit
Fritz, , Stephanie Rinck-Pfeiffer., Gunnar Nuetzmann &
Bernd Heinzmann
12
UKWIR Reuse Report 2005
UKWIR Report Framework for Developing Water Reuse
Criteria with Reference to Drinking Water Supplies Report
Ref No. 05/WR/29/1 in association with AwwaRF & the Water
Reuse Foundation
13
Essex & Suffolk Scheme
CIWEM Awards 2002 The Chris Binnie Award for
Sustainable Water Management:
The Langford
15th March
2013
Page 32
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
No
Concerning
Source
Recycling Plant
14
California Regulations
California Department of Public Health, Draft
Regulations for Groundwater Replenishment with
Recycled Water, November 21, 2011.
15a
Regulatory requirements for
Drinking Water Safety Plans
Regulation 27 of the Water Supply (Water Quality)
Regulations 2000 (SI 2000/3184) in England
15b
Regulatory requirements for
raw water monitoring
Regulation 16A of the Water Supply (Water Quality)
Regulations 2000 as amended by the Water Supply
(Water Quality) (Amendment) Regulations 2007 (SI
2007/2734)
16
DWSP – WHO
http://www.who.int/water_sanitation_health/dwq/wsp05
06/en/index.html
17
Shane Synder ,David Sedlak
and Jorg Drewes
2012 NRC Report – Water Reuse :Potential for
Expanding the Nation’s water supply through reuse of
municipal wastewater (USA)
18
Dan Okun
http://urbanwatererc.org/blog/echoes-dan-okun
19
Addition of AOP to RO
Final Report, West Basin Seawater Barrier Water
Conservation Project, West Basin Municipal Water
District, Independent Advisory Panel Findings,
Conclusions and Recommendations, September 12,
2008.
20
River Trent
River Trent on Tap – Comparison of Conventional and
membrane treatment processes. B.E. Drage et al.
proceedings of the International Conference on
membrane Technology in Water and Wastewater
Treatment, Lancaster University, March 2000
21
Virginia Loudoun MBR plant
http://www.loudounwater.org/ResidentialCustomers/Water-Reclamation/
22
Non-RO treatment
September 2012 Water [Australia] Achieving Drinking
Water reuse without reverse osmosis, L Schimmoller et
al
15th March
2013
Page 33
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
Annex A
1 Page
15th March 2013
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
Annex B
5 Pages
15th March 2013
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
Annex C
6 Pages
15th March 2013
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
Annex D
1 Page
15th March 2013
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
Annex E
2 Pages
15th March 2013
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
Annex F
15 Pages
15th March 2013
IERP Final Report 15/3/13
CONFIDENTIAL TO THAMES WATER
Annex G
8 Pages
15th March 2013