Eccles Wastewater Treatment Works) Compulsory Purchase Order 2016

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UNITED UTILITIES WATER LIMITED (ECCLES WASTEWATER TREATMENT WORKS) COMPULSORY PURCHASE ORDER 2016

PROOF OF EVIDENCE ON BEHALF OF THE ACQUIRING AUTHORITY IN RESPECT OF WATER QUALITY

DR KEITH HENDRY FIFM CENV, APEM LTD

MAY 2018

1. Qualifications, experience and scope of evidence 1.1. I am Dr Keith Hendry, Chairman of the science based aquatic consultancy firm APEM Ltd based in Manchester. I am an aquatic scientist with over 30 years’ experience in water quality and freshwater ecology/fisheries. I have specific expertise in relation to the Manchester Ship Canal (MSC) and urban waterways in general. I was the Scientific Advisor to the Mersey Basin Campaign and its successor organisation, the Healthy Waterways Trust, for 25 years (renamed the Mersey Rivers Trust), becoming a trustee in 2016 and elected Deputy Chairman in 2017. The Mersey rivers, Salford Quays and the MSC have all featured heavily in my long involvement with the Campaign and Trusts. 1.2. I have a Bachelor of Science Degree in Biology (specialising in Fish Biology) from Plymouth Polytechnic and a PhD from Manchester University awarded in 1991 on ‘The Ecology and Water Quality Management of Disused Dock Basins and their Potential for Alternative Uses’. I am a Fellow of the Institute of Fisheries Management and a Chartered Environmentalist. I have published over 40 scientific papers in peer reviewed journals and conference proceedings, many of which relate to the MSC. 1.3. From 1987 to March 2018 I was Managing Director of APEM Ltd, previously having worked for South West Water Authority. Over these 32 years at APEM I oversaw the company’s development into one of Europe’s leading specialist aquatic science consultancy firms, now employing over 100 scientists. In March 2018 I changed roles to become Chairman of the APEM board, responsible for the strategic development of the firm. 1.4. My work on the MSC dates back to 1987 and continues to the present day. My PhD from Manchester University, based largely on the water quality and ecological transformation of Salford Quays, involved extensive scientific investigation into the MSC and its dock basins. I have undertaken many consultancy commissions and over 30 research projects on the MSC, including in relation to: water quality characterisations; artificial water quality management using large scale oxygen injection; sediment contamination and the influence of bed sediments on water quality; and long term fisheries and invertebrate investigations. Some of these studies were instigated in 1987 and remain ongoing. This has provided me with a detailed understanding of the interaction between water quality and aquatic ecology in the MSC. In particular, I have undertaken extensive studies into the impacts of United Utilities’ assets (treated

effluent, storm sewage, and imported water assets) on the water quality and ecological environment of the MSC, including bracket sampling around the Salteye Brook/MSC confluence. 1.5. In 2007, I took part in a major investigation into the main influences on water quality throughout the entire freshwater length of the MSC1. This study was the most detailed examination of the water quality status of the MSC ever undertaken. It investigated the factors that influence water quality, including United Utilities’ treated and storm water discharges, other discharges, the influence of sediments and the form of the MSC itself. The study concluded that the overriding factor influencing water quality (in particular the all-important parameter dissolved oxygen) was the physical structure of the MSC itself. Its artificial steep banks and deep nature facilitate rapid stagnation during dry, still weather conditions that consequently result in rapid oxygen depletion from the sediments up through the water column. 1.6. I provide this Proof of Evidence on behalf of United Utilities in relation to the United Utilities Water Ltd (Eccles Wastewater Treatment Works) Compulsory Purchase Order 2016. 1.7. The purpose of my evidence is: 1.7.1. To provide the background for the CPO Scheme from a water quality perspective; 1.7.2. To clarify the implications for the CPO Scheme in the context of changes to the Salteye Brook and changes to the MSC; 1.7.3. To explain the water quality implications of the alternative proposals now being suggested by the objectors; and 1.7.4. Consequently, to provide a response to objections raised against the CPO Scheme. 1.8. My Proof of Evidence is necessarily of a technical nature and uses a variety of technical terms and abbreviations, which are defined in the Glossary at Appendix 1. 1.9. For the reasons set out below, I consider that the proposals to which the Compulsory Purchase Order relates will be of benefit to water quality in both Salteye Brook and the MSC.

1 APEM (2007) Manchester Ship Canal Water Quality Review. Parts 1 and 2. United Utilities, APEM Scientific Report 410039, September 2007

1.10. I confirm that this Proof of Evidence is true and sets out my professional and honest assessment. I am aware of and have complied with my duties as an expert witness and those as a Chartered Environmentalist.

2. Executive Summary 2.1. Treated sewage effluent from Eccles Wastewater Treatment Works (WwTW) is currently discharged into Salteye Brook, a tributary of the Manchester Ship Canal (MSC). As a consequence, the part of the Brook below the effluent discharge point has significantly lower water quality than that upstream. 2.2. As dealt with in more detail in the evidence of Luke Pearson, the Environment Agency (EA) as the regulator has required the water quality in Salteye Brook to be improved to meet the relevant standards in the Water Framework Directive (WFD). The proposed Scheme will facilitate meeting the required standards set by the EA for Salteye Brook. It will do so by transferring treated effluent directly to the MSC adjacent to the point where Salteye Brook joins it, rather than into the Brook itself. 2.3. Eccles’ final effluent discharge currently increases mean flow in Salteye Brook by nearly 200%, and is therefore the overwhelmingly dominant source of water in the Brook. In contrast, the Eccles final effluent discharge constitutes less than 2% of the overall MSC flow downstream of Salteye Brook, and if transferred (under the CPO Scheme) directly to the MSC would therefore result in much greater dilution than is possible in the Brook. 2.4. Transferring the effluent discharge directly into the MSC in the way proposed, rather than into Salteye Brook, will lead to significantly and immediately improved water quality conditions in Salteye Brook by removing the large majority of its ammonia, biochemical oxygen demand (BOD) and nutrient contamination. Maintaining a discharge into Salteye Brook, even under the more stringent consent standards that would be required for such a discharge, would still result in lower water quality in Salteye Brook than the CPO Scheme transfer to the MSC. 2.5. Transferring the effluent discharge directly into the MSC via the pipe and outfall under the proposed CPO Scheme will achieve this substantial improvement to Salteye Brook, whilst at the same time not resulting in any material detriment to the water quality in the MSC. Indeed, by also providing greater storm flow capacity in the pipe and providing for screening of such flows, there will in fact also be an overall net improvement in the water quality of the MSC achieved by the proposed CPO Scheme. 2.6. The objection on behalf of the Manchester Ship Canal Company Ltd (“MSCCL”) and Peel Investments (North) Ltd (“PI(N)L”) assumes that Salteye Brook has an important role in cleaning the effluent water before it enters the MSC. I consider that this view is incorrect. Salteye Brook’s poor water quality is exacerbated by the

fact that it is a small river now flowing along the former channel of the much larger River Irwell (i.e. substantially wider and deeper compared to the Salteye Brook channel). Hence in its lower reaches it is now therefore considerably larger and slower flowing than a river of this size would normally be, with little gradient. As a consequence, the natural processes of re-aeration that would ordinarily be expected to remove contaminants from the water will not be operating to a significant extent. Currently, Salteye Brook is therefore unlikely to have any material beneficial effect on water before it enters the MSC. It may even reduce water quality further, as oxygen used to break down contaminants chemically will not be replaced. 2.7. Transferring the discharge to the MSC will result in a significantly reduced flow in Salteye Brook. However, the removal of sewage effluent inputs will more than offset any potential disadvantages of this reduced flow. 2.8. The existing and ongoing poor water quality in the MSC is significantly exacerbated by its artificially engineered physical nature (deep, steep sided and slow flowing). This inhibits mixing and replenishment of oxygen from the atmosphere, leading to periodic water quality problems mainly associated with oxygen levels. This can occur irrespective of the quality of inputs, and is particularly prevalent during periods of still, dry weather. Indeed, the physical structure of the MSC is the main driver influencing water quality under still, dry weather conditions, irrespective of any effluent discharges into it. 2.9. A major benefit of the proposed CPO Scheme is to offer a safe refuge with good water quality to fish populations in the MSC below Barton Locks during these periodic episodes of low oxygen concentration. The substantially improved oxygen conditions in Salteye Brook, which will result from removing the sewage effluent currently present, will offer an important fish refuge due to unobstructed passage between the MSC and the Brook. This will provide a substantial benefit compared with the current situation, as areas of refuge from periodic poor water quality in the MSC are sparse. It is unlikely that any alternatives which continue to discharge final effluent into Salteye Brook would offer the same level of benefit to fish populations in the MSC. 2.10. Dilution is widely accepted as a key component of effective treatment of final effluent. It works well when the discharge volume is small compared with that of the receiving water, ensuring that biological and chemical breakdown processes are not overwhelmed. Therefore it is misconceived for MSCCL to describe the proposal under the CPO Scheme as the simple transfer of an existing problem, as this overlooks this important principle. As stated above, the Eccles WwTW

discharge accounts for an average of just 2% of the MSC flow, but it is nearly double the natural Salteye Brook flow. Therefore, a key advantage of discharge directly into the MSC is the dilution effect that this provides within the MSC as compared to the position in Salteye Brook. 2.11. As the proposed new discharge point into the MSC is adjacent to where Salteye Brook currently enters, there will be no deterioration in the MSC compared to the current situation. 2.12. Storm discharges currently enter the MSC via Salteye Brook. Under the CPO Scheme the reduction in storm spills that will occur due to increased storm overflow capacity will have a positive effect on MSC water quality by reducing the frequency and contaminant load of storm discharges. Screening of storm overflows to remove solids will have a further benefit by removing solids that would otherwise be deposited in Salteye Brook and the MSC. 2.13. In order to allow essential maintenance to take place on the CPO Scheme discharge pipe, it is anticipated that a temporary direct transfer to the MSC will be required at Eccles WwTW approximately once every 10 years. The potential effect of this transfer would be a small and very short-term change in water quality in a 1 km stretch of the MSC upstream of Barton Locks. This will have a far smaller effect than the permanent alternative options proposed by MSCCL, which involve pumping storm overflow and in some cases final effluent continuously into this basin. Each of these alternative options would result in deterioration of the MSC upstream of Barton Locks on a continuous basis, which is plainly not preferable to the very infrequent planned maintenance proposal under the CPO Scheme. 2.14. I have assessed other proposed options from a water quality perspective, considering their impacts on Salteye Brook and the MSC. Those proposed by MSCCL either involve continued effluent discharge into Salteye Brook or discharge into the MSC adjacent to Eccles WwTW, upstream of Barton Locks. The former would continue to have a negative effect on Salteye Brook, even under tighter discharge standards. The latter would reduce water quality in the 1 km reach of the MSC between Eccles WwTW and Salteye Brook, due to the discharge being upstream of the point where the effluent currently enters the MSC and where it will enter the MSC under the preferred option. 2.15. It is my strong belief, therefore, that the proposed CPO Scheme will provide the greatest benefit to the water quality and ecology of Salteye Brook and will enhance the natural processes of pollutant dispersal and breakdown by discharging into the considerably larger body of water that is the MSC. I also consider that the MSC will benefit, both directly in terms of a small water quality

improvement and, importantly, ecologically through the creation of an important refuge for MSC fish in Salteye Brook.

3. Background to the proposed scheme 3.1. Preamble 3.1.1. The CPO Scheme is a project to remove the treated sewage discharge from Eccles Wastewater Treatment Works (WwTW) to Salteye Brook and re-route the discharge of treated sewage effluent directly into the MSC at a point immediately upstream of the confluence of the Salteye Brook with the MSC. In addition, storm sewage discharges to Salteye Brook will be reduced in both frequency and volume. 3.2. Sewage treatment in the UK

3.2.1. General background 3.2.1.1. Domestic sewage in the UK is piped from homes to be treated at central Wastewater Treatment Works (WwTWs). Once the effluent has been treated to a quality required to protect the receiving waters, it can be discharged to rivers, lakes or to the sea as final effluent, which is permitted to contain certain concentrations of dissolved contaminants and fine suspended solids. 3.2.1.2. All treated sewage effluent will contain various contaminants, including biochemical oxygen demand (BOD) and ammonia. 3.2.1.3. BOD is not a specific chemical but is instead a measure of the rate at which the water will remove oxygen, through microbial respiration and direct chemical oxidation; these in turn increase with increasing concentration of biologically derived, and therefore decomposable, residues. 3.2.1.4. Ammonia is a compound of nitrogen and hydrogen that is a breakdown product of sewage effluent. It is measured and reported as the concentration of nitrogen, often referred to as ammoniacal nitrogen. 3.2.1.5. The concentration of the contaminants that treated effluent is permitted to contain once discharged is determined by the Environment Agency (EA), which sets permitted levels for each final effluent discharge. The concentrations that are permitted will vary according to the size and sensitivity of the receiving water body. 3.2.1.6. Although WwTWs are designed to treat continuous inputs of sewage, storm sewage overflows are an integral feature of wastewater treatment

systems in the UK. Our sewage treatment systems have evolved to perform the combined function of transporting both sewage effluent and rainwater within the same underground pipes. During periods of heavy rainfall there is a risk of pipes becoming overloaded by excess volume of water. This can compromise operation of the WwTW and can also lead to contaminated water or raw sewage being forced out of pipes into the surrounding environment or even, via the sewage system, into buildings including domestic properties. 3.2.1.7. To prevent this happening, storm overflows have been introduced into the network, in effect acting as a ‘high flow safety valve’; these avoid flooding by allowing excessive flows from high rainfall to be discharged to nearby watercourses. Where they carry combined sewage and surface runoff, these are referred to as combined sewer overflows (CSOs). A key feature of the UK water company Asset Management Plan (AMP) investment programmes since 1990 has been to ensure that these storm sewage overflows discharge diluted sewage and/or primarily rainwater alone. 3.2.1.8. Storm overflow improvements have been achieved by providing sufficient temporary storage within the sewage network to prevent discharge of the ‘first flush’ of untreated water. This ‘first flush’ is often created during the period of rising water levels within the sewer network, at the beginning of rainfall events. During these events any sewage solids in the sewer pipe can be re-suspended by increasing velocities. Subsequently, after the diversion and storage of the ‘first flush’ the sewers contain mainly rainfall and substantially diluted sewage which is then safely discharged, usually via overflow to an adjacent watercourse. It is important to note that this refers to pipes containing foul sewage that has not been through the treatment process, and is not to be confused with final effluent discharge pipes. 3.2.1.9. In the event that storm conditions continue, the substantially diluted sewage is generally passed through screens before being discharged to the environment. The screens are provided to create some level of treatment to protect both the aesthetics and water quality of rivers. In the UK, the screens are set at 6 x 6 mm, meaning anything larger than these dimensions gets caught and is not discharged to the receiving waters, thereby reducing the pollutant load of the discharge. This load can include

objects such as nappies and sanitary towels as well as biological waste (including faeces) 2.

3.2.2. Regulation 3.2.2.1. To achieve regulatory compliance, all sewage discharges rely on a level of dilution to a greater or lesser extent. The regulatory mechanism is designed to set consent and/or volume levels for the discharge. The system requires that modern treatment processes operate within a regulatory framework where the level of treatment and the dilution capacity in the receiving waters are inextricably linked. Thus, there is a relationship between the level of treatment required by the regulator and the ability of the receiving waters to accommodate the treated effluent without environmental damage. Dilution of effluents is a central feature of environmental policy for wastewater treatment in the UK and is a very well- established practice throughout river basins, including the Mersey Basin. 3.2.2.2. The key regulatory driver determining consents for discharge from WwTWs is the Water Framework Directive (WFD). This is European legislation designed to ensure the protection and management of water bodies. Each water body is a defined surface water feature, such as a river or canal. Each will have an associated catchment from which surface drainage or small tributaries will flow into the named water body. 3.2.2.3. The WFD requires all designated waters to aim to achieve Good Ecological Status at the water body level. However, water bodies that are designated as heavily modified (e.g. those with significant engineering in place for a defined use such as navigation or flood risk mitigation) or artificial (e.g. a water body created through construction such as a reservoir) only have to attain Good Ecological Potential. 3.2.2.4. The water body classification is assessed as a combination of ecological status (e.g. fish, invertebrates, physicochemical elements such as phosphates, ammonia etc.) and chemical status (e.g. priority substances), and is determined by measurement of a range of physical, chemical and biological elements. 3.2.2.5. Classifications at the level of each element and of the overall water body are split into five categories: High, Good, Moderate, Poor and Bad

2 These are considered later (Section 9.1) in my response to paragraph 6.19.2 of the MSCCL/PI(N)L Statement of Case.

(with standard colour coding: blue, green, yellow, orange and red), while Good chemical status is set as pass or fail. In order to achieve Good Ecological Status or Potential, all individual elements must be at Good or High Status3. 3.2.2.6. The WFD was originally transposed into UK legislation in 20034. Its requirements are delivered through regional River Basin Management Plans (RBMPs). These are produced every six years and include a baseline classification for each water body5 along with their objectives for 2027, the final deadline for meeting the requirements of the WFD. 3.2.2.7. To meet the requirements of the WFD the UK Technical Advisory Group (UKTAG) produced the relevant water quality standards for different aspects of the water environment. These are set out in the 2015 directions published by Defra6. They set maximum allowable concentrations of contaminants, including ammonia and BOD, which vary according to the type of water body being assessed. 3.2.2.8. Standards relating to ammonia and BOD that are of relevance for my evidence are set out in Table 1 below. 3.2.2.9. With respect to WFD assessment, consideration is given to the range of concentrations that may be experienced at a location. For ammonia and BOD, a 90 percentile value is calculated. This is the concentration below which 90% of readings are expected to fall. Regular monitoring will generate data that can be compared with the standards, in order to determine the actual classification relative to the standards. 3.2.2.10. Salteye Brook and the MSC were originally designated under the Freshwater Fish Directive (FFD), under which standards for Eccles WwTW discharges were set. The FFD was repealed in 2013 and subsumed into the WFD. In 2016 the EA confirmed that the WFD requires protection of water bodies equivalent to that previously afforded by the FFD. This background is considered in more detail in Luke Pearson’s Proof.

3 For Good Ecological Potential, not all ecology elements will be used, depending on their sensitivity to the water body use e.g. flow sensitive species might not be used to classify canals. 4 The current transposing Regulations (so far as England is concerned) are the Water Environment (Water Framework Directive) (England and Wales) Regulations 2017. 5 The baseline is used for deterioration assessments, unless classifications from later years show a confirmed improvement in status. For example, if the baseline was Poor Status but a later year showed a confirmed improvement to Moderate Status, then the Moderate Status would be considered the baseline from which to assess deterioration. 6 Defra (2015) The Water Framework Directive (Standards and Classification) Directions (England and Wales) 2015. London, Department for Environment, Food and Rural Affairs.

Table 1– Ammonia and BOD standards for rivers (Types 3, 5 and 6)

Total ammonia as nitrogen (mg/l) (90 percentile) River type High Good Moderate Poor 3, 5 and 7 0.3 0.6 1.1 2.5

BOD (mg/l) (90 percentile) River type High Good Moderate Poor 3, 5 and 7 4 5 6.5 9

From: Defra (2015). The values given are the maximum allowable for each classification category. River type is determined by the EA on the basis of altitude and alkalinity of the water, Both Salteye Brook and the upper MSC water body are classified by the EA as river Type 3.

3.3. Nationally accepted norms and the influence of the MSC 3.3.1. As mentioned above, to achieve regulatory compliance, all sewage discharges rely on a level of dilution to a greater or lesser extent. The level of treatment and the dilution capacity in the receiving waters are inextricably linked. The balance of this relationship has radically altered over the past 28 years since water company privatisation, with considerable investment in improving effluent quality to meet ever more stringent environmental standards. Improvements to sewage infrastructure are readily observed throughout the Mersey Basin, where many billions of pounds of investment have occurred to bring about remarkable changes in the river systems of the region. 3.3.2. However, whereas in normal riverine environments throughout the Mersey Basin the principle of effluent dilution is a cornerstone of sewage treatment infrastructure, the artificial construction of the MSC introduces a further level of complexity. The deep nature of the MSC and its steep banks are design features that facilitate navigation, but which radically altered the physical structure of the original River Irwell and Irwell Navigation, large sections of which were replaced when the MSC was constructed in the late Victorian era (Figure 1).

Figure 1 - The MSC under construction in the 1890s Note the workman in the foreground who provides an indication of scale. The MSC is typically 9 m deep and 60 m wide, widening to over 100 m in the vicinity of the locks. By comparison, the river Mersey immediately prior to joining into the MSC is typically 30 m wide with a depth of up to 3 m.

3.3.3. The detailed Water Quality Study undertaken in 20077 revealed that even simulated removal of all sewage effluent from the modelled runs still resulted in extensive de-oxygenation of the MSC over whole reaches during still dry weather conditions. Deoxygenation is a feature which has been observed in the MSC, confirming the validity of the models. These conditions could result in significant environmental damage. The same water quality conditions in a normal river reach, such as the River Mersey immediately before it passes into the MSC, would be un-problematic. Hence, the physically engineered structure is the over-riding influence on water quality in the MSC today during dry, still conditions. 3.3.4. The modelling and monitoring processes conducted by the EA and United Utilities confirm the effectiveness of the programme of sewage infrastructure improvements for both treated effluent and storm sewage discharges. In the

7 See footnote 1 above.

Mersey Basin and the MSC in particular, the return of Atlantic salmon8, the most pollution intolerant of fish (which have to negotiate 7 km of the MSC to access their spawning grounds), provides testament to the enormous successes that this approach has achieved in the Greater Manchester conurbation.

8 Documented in various newspaper articles, and in the following peer reviewed publication: Ikediashi C., Billington S and Stevens JR (2012) The origins of Atlantic salmon (Salmo salar) recolonizing the River Mersey in northwest England. Ecology and Evolution 2: 2537-2548.

4. Salteye Brook and the proposed scheme

4.1. Discharges into Salteye Brook 4.1.1. The watercourse that includes Salteye Brook undergoes several name changes along its course. It starts as Folly Brook to the north east of Eccles WwTW in Pendlebury. It then flows through urban areas before becoming Worsley Brook and then Salteye Brook at the Eccles WwTW discharge point. Salteye Brook then flows into the MSC immediately downstream of Barton Locks (Figure 2). 4.1.2. The principal driver for the CPO Scheme is the regulatory requirements set by the EA in respect of the water quality in Salteye Brook. 4.1.3. The Eccles WwTW and its associated storm overflows currently discharge treated sewage effluent and, intermittently under storm conditions, untreated rainwater-diluted effluent into Salteye Brook. There are three storm overflows, whereby under high flows untreated rainwater-diluted sewage is presently diverted directly into the Brook:  Winton storm outfall (SAL 0018);  Eccles WwTW inlet overflow; and  Eccles WwTW storm tank overflow. 4.1.4. SAL 0018 discharges into Worsley Brook underneath the M60 motorway. The Eccles WwTW inlet overflow and Eccles WwTW storm tank overflow discharge via the final effluent pipe into Salteye Brook at the Eccles WwTW FE and storm outfall approximately 600 m downstream of SAL 0018. Locations of these discharges are shown in Figure 2.

Figure 2 - Location of structures and sampling points mentioned in the text

4.1.5. The main outflow of treated effluent water from Eccles WwTW is therefore directly into Salteye Brook 0.95 km upstream of its confluence with the MSC. 4.1.6. Mean flow of Worsley Brook upstream of the outfall, measured at the Worsley Brook gauging station upstream of SAL 0018, is 0.25 m3/s 9. Apart from the intermittently flowing SAL 0018 there are no further inflows between the gauging station and the Eccles WwTW outfall. 4.1.7. The Eccles WwTW outfall discharges at a mean rate of 0.47 m3/s. This is nearly twice the volume of the Brook immediately upstream. Therefore, the major component of the flow in Salteye Brook is the treated final effluent (see Fig. 3a). This is of lower water quality than the river upstream of the discharge.

9 Based on daily mean flows from January 1997 to April 2001, derived from the National River Flow Archive. The gauging station ceased to be operational after April 2001.

Figure 3 – a) Eccles WwTW final effluent outfall to Salteye Brook; b) Salteye Brook reach immediately downstream of Eccles WwTW outfall. Photos taken 18 April 2018

4.2. Salteye Brook WFD status and current water quality 4.2.1. Salteye Brook is part of the “Folly Brook and Salteye Brook water body” for the purposes of the WFD. This water body is classified as Heavily Modified.

Although the WFD requires that it achieves Good Ecological Potential, it is currently only at Moderate Ecological Potential. 4.2.2. In 2016, all of the physico-chemical quality elements were at concentrations consistent with Good or High class, including ammonia (Good) and BOD (High)10. However, these classifications have been calculated for the water body as a whole, whereas EA water quality data collected from Salteye Brook, downstream of the Eccles WwTW final effluent discharge point, indicates that this stretch of the water body is less than Good Status for water quality, as explained below. 4.2.3. The EA has three regular water quality monitoring points along the water body (Figure 2):  Folly Brook, upstream of the Eccles WwTW and SAL 0018 outfalls;  Worsley Brook, also upstream of the Eccles WwTW and SAL 0028 discharge outfalls; and  Salteye Brook, about 30 m downstream of the treated effluent discharge and a little over 600 m downstream of SAL 0018. 4.2.4. Given their locations, these monitoring points give a good indication of the effects of the Eccles WwTW discharges on the water quality of Salteye Brook. 4.2.5. All contaminants show a large increase in concentration at the Salteye Brook sample location compared with the two sites upstream, with oxygen percentage saturation declining. This indicates a deterioration in water quality conditions between the Worsley Brook and Salteye Brook sample locations. While some of this change may be due to other features of the catchment, including runoff from urban areas that enters the river between these two locations, it is likely to be largely due to the presence of the outfall. As this outfall flows continuously, it will have a continuous impact on water quality in Salteye Brook. 4.2.6. EA data for water quality taken from their Folly Brook, Worsley Brook and Salteye Brook monitoring points shows the WFD classifications at each point. My calculations of class, based on five years’ data, are shown in Table 2. Classifications for the Salteye Brook monitoring point are at least one class worse than those at the Folly Brook and Worsley Brook monitoring points, and for BOD the difference is four classes, the maximum possible.

10 EA water body classification published on Catchment Data Explorer: environment.data.gov.uk/catchment-planning/WaterBody/GB112069061430

4.2.7. The WFD water body is 5.865 km in length11, and the length affected by the Eccles WwTW final effluent discharge is therefore 16% of the total length of the WFD water body12.

Table 2 – Water quality WFD class in sampling locations along the Folly Brook, Worsley Brook and Salteye Brook watercourse

Biochemical Ammoniacal Ortho- Oxygen Dissolved nitrogen as phosphate as Demand Oxygen Sample location N P (BOD) (percent (mg/l) (mg/l) (mg/l) saturation) Folly Brook High Moderate High Good Worsley Brook High Moderate High Good

Salteye Brook Bad Poor Moderate Bad

All classifications are based on the data cited in Table 2 compared against the appropriate standards published by Defra (2015). These classifications are based on five years’ data and will be more conservative than classes published by the EA, which use three years’ data.

4.2.8. For ammonia, the target 90 percentile value to achieve Good status is no more than 0.6 mg/l (see Table 1). Actual 90 percentile concentrations, based on data collected by the EA from January 2013 to December 201713, are 0.8 mg/l for Worsley Brook and 3.3 mg/l for Salteye Brook (see Appendix 2 for figures). Therefore, upstream of the Eccles WwTW discharge, the ammonia concentration is close to the target, but downstream it greatly exceeds it. 4.2.9. For BOD, the differences are more marked. The target 90 percentile value to achieve Good Status is no more than 5 mg/l (see Table 1). Actual 90 percentile concentrations, based on data collected from January 2013 to December

11 For source see Footnote 10 above.

12 EA guidance is that no more than 1.5km or 15% (based on whichever is the shorter length) of a water body should be at a status lower than the overall water body status. So for a water body 5.865 km long to be at Good Ecological Status no more than 0.88 km (15% by length) could be at Moderate, Poor or Bad.

13 EA monitoring data derived from environment.data.gov.uk.

201711, are 2.6 mg/l for Worsley Brook and 19.6 mg/l for Salteye Brook (see Appendix 2). Therefore, upstream of the Eccles WwTW discharge the river is within its target, but downstream it greatly exceeds it. 4.2.10. The impact of effluent discharge is a visible feature of the lower Salteye Brook channel, as illustrated in Figure 4. This shows cloudiness of the water; anoxic residues developing on solid surfaces; and the presence of sewage fungus, an indicator of continuous inputs of nutrient-enriched effluent discharge.

Figure 4 - Visual evidence of poor water quality in Salteye Brook a) sewage fungus growing on a discarded pipe close to Eccles WwTW outfall; b) black residues on exposed tree trunks close to the confluence with the MSC, demonstrating anoxic sediment. Photos taken 18 April 2018.

4.3. Effect of Salteye Brook channel structure 4.3.1. Salteye Brook’s poor water quality is exacerbated by the fact that the Brook does not follow a natural river course, but instead empties into the former River Irwell channel (Figure 5). This channel was left as an engineering ‘by-product’ of the construction of the MSC in the period 1887 to 1893. The straight course of the new MSC channel bypasses a bend in the old Irwell river course. This bend in the River Irwell accommodates the location of the confluence with Salteye Brook. This is significant because the lower Salteye Brook channel was extended to include a short section of the much larger River Irwell channel but with only the flow of the Brook (augmented by Eccles WwTW effluent) to fill it.

Figure 5 - a) the current course of Salteye Brook in relation to the former River Irwell channel; b) view of the channel close to the confluence with the MSC Photo taken 18 April 2018.

4.3.2. The former River Irwell channel that now forms the lower reach of Salteye Brook is directly connected to the MSC. Water can move freely between the two water bodies. As the Brook’s channel is large relative to inputs from upstream, it is effectively a backwater of the MSC, with a large volume of water and a flow out into the MSC that is determined by the flow in from Worsley Brook and, currently, from the Eccles WwTW final effluent discharge.

4.3.3. During normal dry weather flow conditions, the current volume of the water in the Salteye Brook channel downstream of the Eccles WwTW discharge is 9.1 Ml14 (Appendix 3). In the absence of the WwTW discharge the water entering this channel would take an average of 10.2 hours to pass along this enlarged channel, whereas for an equivalent length of the river further upstream in a more natural channel, it would be expected to take an average of 0.95 hours (Appendix 3). Even with the addition of the Eccles WwTW discharge, the average time required for water to pass along this channel remains long, at 3.5 hours. 4.3.4. The effect of this is an artificial situation whereby, following construction of the MSC, the Salteye Brook channel is much too large for the flow it contains. Hence, under normal dry weather flows, the stretch downstream of the Eccles WwTW outfall is prone to stagnation, backing up into an artificially deep, slow moving area. The combination of the physical nature of this artificial river course and the concentration of effluent from the Eccles WwTW results in unacceptably poor water quality by modern regulatory standards. This is one of the key drivers for the implementation of the CPO Scheme. 4.3.5. The key water quality issue in Salteye Brook relates to the availability of oxygen in the water. Oxygenation requires mixing with the air, which in turn requires a turbulent water surface to be effective. The water discharged from the effluent pipe is turbulent, entering the brook in the form of a discharge that encourages mixing (Figure 3a). There is a short reach of high gradient river bed immediately downstream, albeit heavily engineered so that turbulence is minimised (Figure 3b). Even allowing for this, however, mean oxygen saturation at the EA Salteye Brook monitoring point is less than 68%15. It is therefore considerably lower than would be expected for an unpolluted river of this type, for which oxygen saturation nearer 100% would be typical. 4.3.6. For the remaining 0.8 km of its length, the deep channel and slow flow is evident in the cloudiness of the water (Figure 4a), as suspended particles are not washed away, while sewage fungus (Figure 4a) is indicative of the effect of high nutrient and organic inputs such as ammonia and phosphate. Even

14 Megalitres. A megalitre is one million litres, equivalent to 1000 cubic metres (m3). It is used as the standard unit for recording large volumes and flows. Conversion of volume to a rate of flow is defined in the glossary under ‘Megalitres’.

15 Data from environment.data.gov.uk. The mean is derived from data collected during the period 2013-2017.

towards the confluence with the MSC, the black film that forms on the bed and banks of the brook (Figure 3b) is indicative of anoxic sediment and therefore of low oxygen concentrations in the water. 4.3.7. There is a lack of features such as weirs or rough stony surfaces, meaning that the amount of oxygen entering the water from diffusion will be very low. Additionally, the cloudiness of the water in the brook is unlikely to be conducive to plant growth (either attached to the river bed or algae in the water column), reducing their ability to add oxygen through photosynthesis. The lack of mixing and limited plant growth indicate that overall there is likely to be a very low input of oxygen. 4.3.8. In summary, the physical structure of Salteye Brook means that it is unlikely that there is much capacity for re-oxygenation due to its width, depth, slow flow and channel uniformity, and therefore, there will be no substantial breakdown of ammonia and BOD before it enters the MSC. However, if any breakdown were to occur this would further reduce oxygen concentrations within Salteye Brook, resulting in water that enters the MSC from Salteye Brook being further de- oxygenated as a consequence of Eccles WwTW final effluent being discharged into it. This would therefore have a negative effect on MSC water quality.

4.4. Eccles WwTW discharge consent limits 4.4.1. The current permitted EA consent limit for discharges from Eccles WwTW into Salteye Brook is 8 mg/l ammonia and 20 mg/l BOD; however, the EA has stated that if United Utilities fails to remove the final effluent discharge from Salteye Brook then future consent standards imposed on this discharge will be more stringent, with the BOD limit remaining at 20 mg/l but the ammonia limit being reduced to 2 mg/l. 4.4.2. Accordingly, whilst the final effluent discharge concentration currently meets the EA discharge consent requirements for ammonia, and indeed is currently considerably lower than the consent limit, compliance with the tighter limit of 2 mg/l would not be possible without significant change to the operation of Eccles WwTW, and even then an upgrade in treatment would still result in water quality worse than if the discharge were to be removed entirely from Salteye Brook. 4.4.3. Diversion of the discharge directly into the MSC via the pipe and proposed outfall will, by contrast, take advantage of the extra dilution afforded beyond that of Salteye Brook. It would require no further modification and no tightening of the discharge consent, whilst meeting statutory environmental requirements and resulting in a substantial reduction in ammonia concentration in Salteye Brook.

From an ecological and fish perspective, this would be a substantial and immediate improvement in water quality. 4.4.4. For BOD, the concentration in the final effluent discharge is currently within the discharge consent. There would be no associated improvement in water quality by allowing the discharge to continue into Salteye Brook. Diversion into the MSC via the proposed pipe and outfall, in contrast, would result in a substantial reduction in BOD concentration in Salteye Brook. As with ammonia above, this represents a substantial and immediate improvement in water quality from an ecological and fish perspective.

5. The proposed scheme – water quality effects on Salteye Brook 5.1. Final effluent discharge 5.1.1. The location of the outfall of the new pipe is designed to reduce direct inputs into Salteye Brook and therefore to improve its water quality. The proposed location of the new outfall on the MSC is designed to take advantage of the decrease in elevation below the locks, thereby eliminating pumping costs by utilising gravity for the effluent discharge16. 5.1.2. Transfer to the proposed new infrastructure under the CPO Scheme would divert all of the current continuous, treated effluent discharge away from Salteye Brook, thereby leading to significantly and immediately improved water quality conditions within the Brook, as described above. 5.1.3. The effect of the CPO Scheme on water quality in Salteye Brook, prior to its confluence with the MSC, was calculated based on the following criteria:  The current impact of the main Eccles WwTW discharge on ammoniacal nitrogen and BOD concentrations; and  The predicted impact on ammoniacal nitrogen and BOD concentrations should the discharge stop. 5.1.4. The CPO Scheme will achieve compliance with water quality standards by discharging the effluent from Eccles WwTW directly into the MSC. In the MSC the level of dilution is many times greater than that afforded by the flows in Salteye Brook (see Section 6.2 below). By removing the Eccles WwTW discharge from Salteye Brook, the water quality in the Brook would have the potential to improve significantly and to mirror the quality recorded for Worsley Brook upstream of the current discharge. This would include the potential for WFD classifications to improve, with elements such as BOD improving from Bad Status to High Status and ammoniacal Nitrogen improving from Poor Status to Moderate Status, as set out in Table 3 below.

16 United Utilities Statement of Reasons, paragraph 3.6

Table 3 – Calculated water quality concentrations for the Salteye Brook under two scenarios; with the discharge from Eccles WwTW (current) and without the discharge (proposed CPO Scheme)

Under proposed Contaminant Current CPO Scheme Calculated 90 percentile 3.3 0.8 Ammoniacal concentration (mg\l) nitrogen Calculated WFD Bad Moderate classification Calculated 90 percentile 11.9 2.3 BOD concentration (mg\l) Calculated WFD Bad High classification

5.1.5. This improvement would have a positive effect on 16% of the overall water body length which is the most adversely affected part of the water body. The improvement would also help protect and improve the water body as a whole, including its ecology. 5.1.6. Ammoniacal nitrogen would still be classed as below Good (see Table 3), but this is a consequence of other processes within the catchment affecting water quality in Salteye Brook, and improvements afforded by transfer of the Eccles WwTW final effluent discharge will make it easier to achieve Good class throughout the water body length.

5.2. Effect of reduced flow 5.2.1. As noted above, the lower reach of Salteye Brook (the former River Irwell channel) is effectively a backwater of the MSC, with a large volume of water and a flow out into the MSC that is determined by the flow in from both Worsley Brook and also the Eccles WwTW final effluent discharge. Removing the Eccles WwTW final effluent will reduce this flow significantly and therefore reduce the rate at which water moves through the channel. I therefore also consider the water quality implications of this.

5.2.2. Removing Eccles WwTW’s discharges from Salteye Brook would have a direct, positive impact on the Brook’s water quality by removing the large majority of the Brook’s ammonia, BOD and nutrient contamination. The sewage fungus that currently grows extensively in the organically enriched water would no longer be able to establish, reducing both its negative effect on oxygen concentrations through respiration and the volume of decaying organic matter that it creates once it dies and begins to decompose. Both of these changes would reduce the demand on oxygen in the water by reducing the overall organic material content of the brook. Water clarity would increase as a result of the reduction in suspended solids, thereby increasing plant growth which would enhance oxygenation through photosynthesis. 5.2.3. Therefore, in summary, while flow would be slower in Salteye Brook following cessation of the Eccles WwTW discharge, the positive impacts of reducing BOD, ammonia and nutrient loads through the processes described above would more than offset this, leading to improved water quality in the lower reaches of the Brook, and helping to keep oxygen levels high and within the requirements of the WFD.

5.3. Effects on Ecology and Fish Populations 5.3.1. As discussed above, the CPO Scheme provides substantial benefits in terms of water quality to ecology and fish populations within Salteye Brook. However, there are also important benefits from the scheme to fish populations within the MSC. Previous work17 identified the importance of off-line areas (mainly the feeder rivers and inflowing tributaries) to act as fish refuges during periods of low oxygen in the MSC. As discussed in Section 3.3 above, during dry, still conditions stagnation in the MSC can result in low oxygen levels, driven largely by its physical structure. Access to refuge areas, where fish can escape from low oxygen stress, is of great importance in preventing fish kills. 5.3.2. Under current conditions, it is unlikely that Salteye Brook can perform this function due to the stagnant nature of the water contained within the oversized channel. However, by implementing the CPO Scheme, much improved water quality within Salteye Brook will result in substantially improved oxygen conditions in the Brook. This will offer an important fish refuge with unobstructed passage between the MSC and the Brook providing a substantial benefit

17 APEM (2007) Manchester Ship Canal Strategic Review of Fish Populations. United Utilities, APEM Scientific Report 410039, September 2007

compared with the current situation. It is unlikely that any of the alternatives proposed, which result in maintaining legally compliant but higher levels of BOD and ammonia within the Brook, would offer the same level of benefit to the fish populations of the MSC.

5.4. Storm discharge 5.4.1. The storm overflows identified in Section 4.1 above are currently considered to be ’Unsatisfactory Intermittent Discharges’ (UIDs) by the EA. This is due to their influence on both water quality and aesthetic impacts, as detailed in Luke Pearson’s Proof of Evidence. 5.4.2. In addition to the improvements in water quality in Salteye Brook from transferring Eccles WwTW final effluent directly into the MSC, the CPO Scheme would lead to an improvement due to a reduction in the number of storm related spills, specifically: 5.4.2.1. a reduction in spill frequency to a one in five year event due to increased storage. This would be a reduction in both the number and overall volume of spills compared to the current situation (See Appendix 4 for details); and 5.4.2.2. the transfer of Eccles WwTW overflows directly to MSC, rather than via Salteye Brook. 5.4.3. The significant reduction in number of storm discharges from one of the CSOs and complete diversion of the other two from Salteye Brook would result in a clear and unambiguous improvement in water quality in the Brook. As I identify below, there will also be a net improvement in water quality in the MSC.

6. The CPO Scheme – water quality effects on Manchester Ship Canal 6.1. Current status of the MSC 6.1.1. The MSC contains five locks and runs for 58 km from Salford Quays in Manchester to Eastham Locks, where it joins the Mersey estuary. The MSC has a standard design with steep sides and a flat bottom to aid navigation (Figure 1). The depth and width of the MSC vary slightly down its course, but its depth is typically 9 m and normal width is 60 m. Upstream of Barton Locks the MSC is supplied with water by capturing flow from the rivers in the Irwell catchment, in particular the Rivers Irwell, Irk and Medlock. There are no further significant inputs upstream of Barton Locks. 6.1.2. The MSC passes through Barton Locks approximately 6 km downstream of Salford Quays and 1 km downstream of Eccles WwTW. The Barton Locks system is, as a whole, made up of two locks: a larger one adjacent to the north shore and smaller one in the centre. There is some leakage of water through the locks when the gates are closed, but the main flow of the MSC when the locks are closed passes through a sluice system on the south bank. Immediately downstream of Barton Locks, on the southern shore, is the final effluent discharge from Davyhulme WwTW, which creates considerable additional flow and turbulence (Figure 6).

Figure 6 - The MSC, looking upstream from below the Salteye Brook confluence Photo taken 18 April 2018

6.1.3. The white water in Figure 6 is mainly due to the turbulence caused by the Davyhulme WwTW final effluent discharge on the south bank, in front of the sluices. The locks are towards the north bank, hidden by the trees in the photograph. 6.1.4. The MSC is split across two WFD water bodies, the “Irwell / Manchester Ship Canal (Irk to confluence with Upper Mersey)” water body and the main “Manchester Ship Canal” water body. The reaches of relevance to this work are all in the upstream Irwell / Manchester Ship Canal (Irk to confluence with Upper Mersey) water body, which is designated as Heavily Modified. 6.1.5. The Irwell / Manchester Ship Canal (Irk to confluence with Upper Mersey) is currently classified as being at Moderate Ecological Potential due to missing Mitigation Measures (e.g. physical alterations to the overall water body such as fish passes at weirs) and water quality. In 2016 the physicochemical elements were classed as Bad (dissolved oxygen), Poor (ammonia and orthophosphate) and Good (BOD)18. This indicates that the MSC already has a significant water quality problem, which the EA have stated is caused by physical modifications to the water body (i.e. alterations made for navigation) as well as by point source discharges and diffuse pollution. The long-term water quality objectives for the MSC18 are noted as Poor Status for ammonia and orthophosphate, and Moderate Status for dissolved oxygen; i.e. an improvement is required only in dissolved oxygen. No objective has been set for BOD. 6.1.6. There is only one EA sample point (immediately upstream of Barton Locks) within close proximity to Salteye Brook and the CPO Scheme. An analysis of EA monitoring data from this location is shown in Table 4. This shows that water quality at this point is consistent with the overall water body assessment and is failing to achieve Good Status for any element, apart from BOD, when comparing against the WFD standards in Table 1.

18 EA water body classification published on Catchment Data Explorer: http://environment.data.gov.uk/catchment-planning/WaterBody/GB112069061452

Table 4 – Water quality in the MSC in upstream of Barton Locks

Biochemi- Ammonia- Ortho- Total cal Oxygen cal nitrogen Oxygen phosph- suspend- Demand as N ate as P ed solids (BOD) Sample (10 location (90 (90 percentile (mean - (mean - percentile - percentile - -percent mg/l) mg/l) mg/l) mg/l) saturation ) Concen- 4.0 1.1 33.8 0.3 10.0 Upstream tration Barton WFD Status Good* Poor* Bad Poor - Locks 2027 - Poor Moderate Poor - Objective** Data from environment.data.gov.uk. All values are means derived from data collected during the period 2013- 2017. * = at the upper class boundary so recorded as the lower classification as a precautionary approach ** = the objectives are only set for the main determinands used for compliance.

6.1.7. The poor water quality is significantly exacerbated by the physical nature of the MSC (as described in Section 3.3), which inhibits mixing and replenishment of oxygen from the atmosphere, leading to low dissolved oxygen levels.

6.2. Final effluent discharge 6.2.1. MSCCL has contended that the proposed CPO Scheme would lead to a reduction in water quality in the MSC19 . This is not the case. There will be no deterioration in consequence of final effluent discharge (as I have explained already) and MSCCL has ignored the improvement in water quality that will in fact be achieved by the CPO Scheme in respect of storm water flows (as I deal with in further detail below). In respect of final effluent discharges, I would note in particular as follows: 6.2.1.1. The final effluent that would be discharged via the new outfall is within roughly 10 m of the existing confluence with Salteye Brook. That already

19 MSCCL Statement of Case, paragraph 1.4.2

contains the existing discharge of final effluent made into the Brook. As such this represents a scenario where the load received, and the location of its receipt into the MSC is, to all intents and purposes, the same before and after the CPO Scheme. Other things being equal, there could therefore be no deterioration in water quality in the MSC in consequence of this. 6.2.1.2. MSCCL appear to be contending that all other things are not equal, and that Salteye Brook has an important role in cleaning the effluent water before it enters the MSC itself. Quite apart from the issues this raises with respect to Salteye Brook itself, the cleansing process upon which this assumption relies does not occur, and there could in fact be further deterioration in water quality before it enters the MSC as a result of stagnation in the Salteye Brook. Accordingly, discharging via the pipe and outfall can only lead to a potential improvement in relation to the material discharged into the MSC, rather than the other way around. This is considered in more detail in section 4.3 above. 6.2.1.3. The MSC already suffers from poor water quality upstream of Salteye Brook caused by a range of pressures, particularly the physical nature of the MSC. This is not related to, and remains unaffected by, the proposal. The EA have also set objectives that either show no improvements are expected (for ammonia and phosphate) or only relatively minor improvements are predicted (for dissolved oxygen) in the MSC. I have already identified that that the proposal will not adversely affect water quality from the current baseline and therefore would not affect WFD status or future objectives. 6.2.2. The key advantage of discharge directly into the MSC via the proposed scheme will be the dilution effect that this provides, which, as described above, is the basis of effective treatment of final effluent. Dilution works well when the volume of the discharge is small compared with that of the receiving water, ensuring that biological and chemical breakdown processes are not overwhelmed. Here, the advantage of direct discharge into the MSC, rather than via Salteye Brook, is clear: from the relative size of each of the water sources it is plain to see that the MSC dwarfs both the Eccles WwTW discharge and Salteye Brook in volume (Table 5).

Table 5 – Discharges of the MSC and inflows

Percentage of total in Mean MSC downstream of Water body discharge Salteye Brook (Ml/day) confluence MSC upstream of Salteye Brook (inputs from 1680.2 81.4% R Irwell, R Irk and R Medlock)

Davyhulme WwTW 321.8 15.6%

Eccles WwTW 40.9 2.0%

Salteye Brook (excluding Eccles WwTW) 21.6 1.0%

MSC downstream of Salteye Brook 2064.5 100% confluence

6.2.3. The data for river flows indicates that there is 41 times more flow in the MSC than in Salteye Brook, indicating a significantly greater potential for dilution. Additional dilution is also afforded by Davyhulme WwTW which, although located on the south bank opposite the proposed CPO Scheme outfall, will mix with it. By comparison, flow data for Worsley Brook (21.6 Ml/day) indicates that it only has half the flow of the discharge from Eccles WwTW and so has very limited dilution potential. As such a direct discharge to the MSC would provide greater benefits, including protecting Salteye Brook from deterioration. 6.2.4. The effect of the CPO discharge of final effluent on water quality in the MSC has been investigated by comparing the dry weather flows from the WwTW, the MSC and Salteye Brook (the ‘load’ of sewage related contaminants) at the following two locations before and after implementation of the scheme:  Upstream of Barton Locks and the proposed CPO discharge.  Downstream of the Salteye Brook confluence and the CPO discharge.

Table 6 – The calculated 90 percentile concentrations of ammonia and BOD upstream and downstream of the proposed CPO discharge

Downstream of CPO MSC upstream of Determinand Scenario pipe and Salteye discharges Brook

Current 1.1 1.2 Ammonia (mg/l) Proposed 1.1 1.2 Current 4.0 5.7 BOD (mg/l) Proposed 4.0 5.7

See Appendix 2 for details of calculations carried out.

6.2.5. Table 6 shows the comparison of the calculated 90 percentile concentrations for ammonia and BOD between the current situation and the prediction for when the proposed scheme is in place. The water quality modelling clearly shows that for each of the two locations, there will be no change in ammonia or BOD concentrations. This is due to the fact that, as noted above, the new discharge is close to the current confluence of the Salteye Brook and MSC. It will therefore have the same conditions, flows etc. This is a precautionary assessment because, as explained above (Section 4.3), the current situation in Salteye Brook has the potential to reduce water quality further, rather than improve it as claimed by MSCCL.

6.3. Storm discharge 6.3.1. Storm discharges currently enter the MSC via Salteye Brook. Under the CPO Scheme they would continue to enter the MSC, but those from the Eccles WwTW storm overflows would enter directly rather than via Salteye Brook. 6.3.2. The planned increase in storm water storage capacity would in fact reduce the number of such discharges into both watercourses. Modelling carried out by United Utilities has shown that the overall volume of storm water actually discharged into the MSC would be lower than currently (see Appendix 4). Therefore, water quality in the MSC will benefit in two ways relative to the current situation: 6.3.2.1. The lower total volume of storm overflows discharged will result in lower pollutant loads into the MSC. United Utilities’ modelling indicates that total BOD will be reduced by 6.4% (see Appendix 4). 6.3.2.2. The much lower frequency of overflows will enable the natural cleansing processes of the water to operate more effectively, by giving extra time to disperse and break down pollutants before the next load is discharged. 6.3.3. In addition, the increased storm capacity will not only improve water quality by lowering volumes discharged, but the overall impact of each storm discharge

would also be materially different from the current situation. In particular, the provision of extra storage capacity will retain the ‘first flush’ contaminants, as described in Section 3.2, which will further reduce the overall contaminant load that is discharged to the MSC. 6.3.4. In summary, therefore, reduction in frequency and contaminant load of storm discharges will result in an overall net benefit to the water quality of the MSC.

6.4. Effect of diversion away from Salteye Brook 6.4.1. MSCCL also appear to object to the CPO Scheme on the basis that the effluent will no longer pass along the Salteye Brook channel before it discharges into the MSC, claiming that the consequence of this is that the potential will be lost for such discharge to be oxygenated, and its load of BOD and ammonia broken down to some degree so as to reduce contamination of the MSC20. 6.4.2. This claim is based on a flawed assumption in relation to the potential for Salteye Brook to clean the water. As I have already discussed (see Section 4.3), the ability of Salteye Brook to oxygenate its water is compromised by its channel structure. It occupies a former channel of the River Irwell, which has very little gradient. Therefore, it is very slow flowing. This, combined with the absence of features that would break its surface and encourage mixing with the air, means that its ability to absorb oxygen is limited to simple diffusion across its surface. This is a very slow process that can be easily overwhelmed by removal of oxygen from the water by processes such as bacterial respiration. 6.4.3. Therefore, even if the water in Salteye Brook were clean, its ability to absorb the oxygen needed to reduce BOD and break down ammonia would be limited. However, the water is not clean, being dominated by the Eccles WwTW final effluent that accounts for approximately two thirds of its normal volume of flow downstream of the outfall discharge. This significant extra load of contaminants leads to the rapid reduction in oxygen in the Brook, which in turn suppresses the removal of these contaminants. 6.4.4. In some situations, the addition of nutrients into water from final effluent discharge can encourage growth of algae, which may create oxygen as a by- product of photosynthesis. However, the cloudiness in the water in this

20 MSCCL Statement of Case, paragraph 6.20

watercourse reduces light availability21. Therefore, the ability of algae to photosynthesise is also reduced. Where floating algae do grow their cells will be likely to settle in large numbers on the river bed where their decomposition in the anoxic sediment will increase, rather than decrease, BOD. In addition, another beneficiary of increased nutrients is sewage fungus. This is abundant in the channel (Figure 4a). It respires, leading to further removal of oxygen. Once the sewage fungus dies, its remains will break off from the solid structures on which it grows, but the low flow rate of the brook will ensure that it is soon deposited in the sediment, where its decomposition will further remove oxygen and will increase BOD and ammonia production. 6.4.5. The removal of oxygen from the sediment will exacerbate the water quality state further, as decomposition in the absence of oxygen will encourage the creation of more ammonia in the sediment. 6.4.6. In summary, therefore, there is little potential for a natural cleansing process in the Salteye Brook channel to operate within the current discharge. However, there is potential for it to have a detrimental effect by increasing the BOD load. It is appropriate, therefore, to assume no improvement in water quality of the final effluent before it reaches the MSC. A more realistic approach would be to assume further deterioration in water quality as its passes along Salteye Brook. This is a conclusion supported by the current condition of the Brook close to its confluence, which is characterised by cloudy water and evidence of anoxic sediment (via bubbling). 6.4.7. If final effluent discharges into Salteye Brook were to continue, they would be subject to a tighter consent limit for ammonia. However, even if this were the case, I have already demonstrated earlier (Paragraph 4.4.2) that this would result in relatively little reduction in ammonia concentration and no reduction in BOD concentration. Therefore, Salteye Brook would continue to be heavily contaminated and its capacity for cleaning the water severely compromised.

6.5. Planned maintenance 6.5.1. In order to allow essential maintenance to take place on the discharge pipe, it is anticipated that a temporary direct transfer to the MSC will be required at Eccles WwTW approximately once every 10 years. Using data on current discharge and concentrations, the potential effect of this transfer on water

21 Potential causes of cloudiness are sediment from upstream; resuspension of bed sediment; inorganic effluent suspended solids; and floating microbial organisms such as bacteria and algae (which can impede each other’s growth through shading).

quality upstream of Barton Locks has been modelled and the results are shown in Table 7. 6.5.2. Whilst this would give rise to a small deterioration in water quality in the MSC (extending downstream as far as the Salteye Brook confluence) during such very occasional temporary transfer, there are four important points to note: 6.5.2.1. The deterioration is very small and no deterioration in WFD status of the MSC will result. 6.5.2.2. The deterioration is short term and will occur very infrequently (i.e. planned to occur once every ten years for a three-week period). Maintenance will be timetabled. If it takes place during dry periods then storm overflows can be avoided, thereby ensuring that water quality in the basin upstream of Barton Locks is not compromised. 6.5.2.3. Any temporary effect of this nature is significantly outweighed by the permanent net beneficial effects to the MSC that come from the CPO Proposed Scheme that I have described above. 6.5.2.4. Finally I note that the MSCCL in its Statement of Case (paragraphs 7.22 and 7.23) has put forward what it considers to be five alternative options. However, four of these would involve pumping storm overflow into this basin of the MSC at this location on a permanent basis, and two of them would also involve pumping final effluent into this basin permanently (Section 8.3). Each of these options would result in permanent deterioration of the MSC upstream of Barton Locks on a continuous basis as compared with the very infrequent planned maintenance proposal advocated by the CPO Scheme.

Table 7 – Impact of temporary transfer of Eccles WwTW effluent on water quality in the MSC above Barton Locks

Normal operation Temporary transfer concentration (mg/l) concentration (mg/l) 90 90 Mean mean percentile percentile Ammoniacal nitrogen as N 0.7 1.1 0.8 1.2 BOD 2.6 4.0 2.8 4.3 See Appendix 2 for details of calculations carried out.

7. Conclusions on impacts of the CPO Scheme 7.1. The principal objective of the proposed CPO Scheme is to deliver improved water quality conditions in Salteye Brook, which currently suffers from high loadings of contaminants relative to its volume and flow. The CPO Scheme will deliver clear, unambiguous and significant benefits to the water quality, and therefore the ecology, of Salteye Brook compared with the current situation, and also compared with any alternatives that involve continued discharge of final effluent (even under more stringent standards) into the Brook. 7.2. By locating the proposed new effluent discharge adjacent to the Salteye Brook confluence, so transferring the effluent discharge directly into the MSC rather than via Salteye Brook, the scheme will enable the significant improvement in Salteye Brook to occur whilst having no detrimental impact on the MSC. Moreover, this transfer will take full advantage of the dilution process in the MSC that is a universally accepted principle of final effluent treatment. 7.3. The objections of MSCCL are, with respect, misconceived. There is a suggestion from MSCCL that the CPO Scheme involves a simple transfer of an existing problem from one water body to another. This betrays a misunderstanding of the way in which water quality issues arise and fails to recognise the basic principle of the well-established use of, and benefits afforded by, dilution in a large body of water and the nationally recognised norms of sewage treatment in this respect. For the reasons I have explained, the removal of the discharge of effluent into the Salteye Brook will result in a significant improvement to that waterbody and the provision of the continued discharge of that effluent into the MSC in the same location as the Salteye Brook confluence will not result in any deterioration in the quality of the water in the MSC, but rather will involve the continued beneficial dilution of such discharge in the MSC. 7.4. As to MSCCL’s claims in respect of adverse effects on water quality in the MSC, I have explained that the real issues associated with water quality in the MSC are largely due to its artificial physical structure. The discharge from Eccles WwTW currently plays no significant part in that overall quality. But in any event, the CPO Scheme will not cause any deterioration in relation to effluent, as this will continue to discharge into the MSC as before in the same location. In relation to net water quality, the position will in fact be improved by the management of storm flows by additional storage, the overall contaminant loadings will be reduced and there will be a consequential net benefit to the water quality in the MSC.

7.5. In addition, MSCCL overlooks the fact that there is likely to be an ecological benefit to fish populations in the MSC, not simply from the net improvement in water quality in MSC itself, but also in consequence of the significant improvement in water quality of Salteye Brook. There are no physical barriers to movement for fish between the MSC and Salteye Brook. The Brook has the potential to be an important habitat and refuge for fish within the canal ecosystem. In particular, following implementation of the CPO Scheme, the Brook will offer improved water quality for fish, and this will also serve to act as a fish refuge for fish in the MSC during periods of poor water quality in the Canal that can occur during still, dry weather conditions. Currently the poor water quality in the Brook limits the value of this habitat to fish populations and offers little prospect of refuge during low oxygen events. 7.6. In conclusion, in my professional judgment, the proposed CPO Scheme is a highly desirable solution in terms of water quality, particularly for Salteye Brook but also for the MSC and its fish populations.

8. Alternative options 8.1. Alternatives to the CPO Scheme have been considered previously as part of United Utilities’ optioneering exercise, and are summarised in its Optioneering Report (2018)22. I consider these alternatives from a water quality impact perspective below.

8.2. Alternatives in United Utilities’ Statement of Reasons 8.2.1. Eleven options have been considered in further detail in United Utilities’ Optioneering Report (2018). Their impacts on water quality in Salteye Brook and the MSC relative to the preferred option are considered briefly below. 8.2.2. Option 1 – this was the option that has been taken forward as the CPO Scheme. 8.2.3. Option 2 – Final effluent and storm flows would be pumped into the MSC adjacent to Eccles WwTW. Compared with Option 1, this would result in a lower water quality in the MSC reach between Eccles WwTW and the Salteye Brook confluence. This is equivalent to the scenario considered above in Section 6.5. 8.2.4. Options 3, 6a, 6b, 7a and 7b – The existing outfall would be retained for discharge of final effluent and storm overflows into Salteye Brook. Compared with Option 1, this would result in a lower water quality in Salteye Brook. 8.2.5. Options 5a and 5b – Treated effluent and storm flows would be transferred from the Eccles WwTW site to Davyhulme WwTW, with additional treatment at Davyhulme WwTW. This would give equivalent water quality benefits to Option 1 in Salteye Brook. In the MSC the enhanced treatment at Davyhulme WwTW may result in a very slight improvement relative to the improvement already achieved by Option 1, although as the Eccles discharge would be a small proportion of the combined Davyhulme discharge, this would have little if any material impact on the MSC. 8.2.6. Options 8 and 9 – The existing outfall would be retained for discharge of final effluent to Salteye Brook. Storm overflows would be pumped into the MSC adjacent to Eccles WwTW. Compared with Option 1, this would result in lower water quality in Salteye Brook and, due to storm discharges, lower water quality in the MSC reach between Eccles WwTW and the Salteye Brook confluence. 8.2.7. In summary, from a water quality perspective almost all of the alternative options that were considered in detail would result in lower water quality in

22 United Utilities plc (2018) Optioneering Solution Report. Eccles WwTW CPO. Final version. 9 May 2018.

Salteye Brook or the MSC compared with the preferred option. Only the options that involve transfer to Davyhulme for treatment would result in equivalent water quality relative to the preferred option.

8.3. Alternatives suggested in MSCCL’s Statement of Case 8.3.1. MSCCL proposed five alternative options in its Statement of Case (SoC). Two of the proposed alternatives were identified as options already considered by United Utilities. For the remaining three options, no details were given in the SoC other than those provided below. Therefore, I have made the following assumptions:  Where no different discharge of final effluent is stated by MSCCL, it is assumed that this would continue be into Salteye Brook at its current discharge location.  Where pumping final effluent or storm flows upstream of Barton Locks is proposed, this would be pumping into the MSC adjacent to Eccles WwTW. 8.3.2. My assessment of the impact on water quality of each of the five proposed options relative to United Utilities’ preferred option is detailed below and summarised in Table 8 below. 8.3.3. Each of MSCCL’s options (which I identify below by reference to the relevant paragraph in MSCCL’s SoC) would result in reduced water quality in one or both of Salteye Brook and the MSC, compared with United Utilities’ preferred option. 8.3.4. Where water quality would be lower in Salteye Brook as compared with the CPO Scheme, this is because the proposal is to continue discharging final effluent into the Brook, by contrast to the CPO Scheme. 8.3.5. Where water quality would be reduced in the MSC this is because the proposal is to discharge final effluent and/or storm flow into the MSC adjacent to Eccles WwTW. This results in a pollutant load being added to the MSC above Barton Locks where currently there is no discharge from Eccles WwTW. As a consequence, approximately 1 km of canal length, between Eccles WwTW and the Salteye Brook confluence will be affected which is not currently affected and would not be affected under the CPO Scheme. 8.3.6. In summary, therefore, and as I explain in greater detail below, all of the proposed MSCCL alternative schemes will result in reduced water quality compared with United Utilities’ preferred scheme.

Table 8- Summary of impact of proposed MSCCL schemes on water quality in Salteye Brook and the MSC Orange shading signifies an anticipated reduction in water quality relative to United Utilities’ preferred CPO Scheme

SoC SoC SoC SoC SoC MSCCL paragraph paragraph paragraph paragraph paragraph Proposal 7.22.1 7.22.2 7.22.3 7.23.1 7.23.2 Location of Not stated. Not stated. final effluent Salteye Assumed Assumed MSC above MSC above discharge Brook Salteye Salteye Barton Locks Barton Locks Brook Brook Location of Salteye MSC above MSC above MSC above MSC above storm flow Brook Barton Locks Barton Locks Barton Locks Barton Locks discharge Salteye Brook Lower water Lower water Lower water Water quality Water quality relative to quality quality quality unchanged unchanged CPO Scheme MSC above Barton Water Locks Lower water Lower water Lower water Lower water quality relative to quality quality quality quality unchanged CPO Scheme

8.3.7. SoC paragraph 7.22.1 Biological Aerated Flooded Filter (BAFF) treatment plus additional storage, proposed by UUWL as ‘Option 3’ in the SoR/SoC This would retain the existing outfall for discharge of final effluent and storm overflows into Salteye Brook and assumes BAFF treatment of that effluent to improve its quality. However, it would still result in a reduction in water quality in Salteye Brook compared to that achievable if the discharge were removed entirely.

8.3.8. SoC paragraph 7.22.2 Nitrifying Submerged Aerated Filter (NSAF) Tertiary Treatment at Eccles WwTW combined with pumping storm flows upstream of Barton Locks 8.3.8.1. This would retain the existing outfall for discharge of final effluent and storm overflows into Salteye Brook and assumes NSAF treatment of that effluent to improve its quality. However, it would still result in a reduction in water quality in Salteye Brook compared to that achievable if the discharge were removed entirely. 8.3.8.2. Pumping storm flows into the MSC upstream of Barton Locks would add new storm water into a part of the MSC basin where it does not currently occur. This would inevitably reduce the water quality in this reach. If discharged adjacent to Eccles WwTW, which I assume it would need to be to avoid the need to lay a long pipe, this would reduce water quality in a length of MSC approximately 1 km long compared to both the current situation and that under the CPO Scheme. 8.3.8.3. In contrast to the option addressed in paragraph 8.3.7 above, no additional storage is mentioned. The assessment above assumes that extra storage capacity is included, but if not then the frequency of spills would be greater than under the CPO Scheme. Consequently, the deleterious effect on water quality in the reach of the MSC upstream of Barton Locks would be greater. 8.3.9. SoC paragraph 7.22.3 Replacement treatment at Eccles WwTW (Activated Sludge Process (ASP)) combined with … pumping storm flows upstream of Barton Locks 8.3.9.1. This option differs from that described in paragraph 8.3.8 above in terms of the type of on-site treatment at Eccles WwTW. However, in terms of both final effluent and storm discharge requirements it appears to be the same. Therefore, the same issues arise and it can only be concluded that this will result in a reduced water quality in Salteye Brook and the MSC compared to the CPO Scheme. 8.3.10. SoC paragraph 7.23.1 Pumped discharge to MSC, proposed by UUWL in ‘Option 2’ in the SoR/SoC 8.3.10.1. From a water quality perspective this proposal would result in Salteye Brook water quality being equivalent to that of the CPO Scheme, as no final effluent would be discharged into the Brook. However, discharge of the effluent into the MSC adjacent to Eccles WwTW would reduce water quality in a length of MSC approximately 1 km long compared to both the

current situation and that under the CPO Scheme. Therefore, this is not an improvement over the CPO Scheme in terms of water quality, but rather a deterioration for the MSC. 8.3.11. SoC paragraph 7.23.2 Discharge of Final Effluent (FE) to MSC (north route) and pump storm flows upstream of Barton Locks 8.3.11.1. This is presumed to be similar to the ‘Option 2’ considered under paragraph 8.3.10 above, but with the final effluent being discharged at a different location. Its overall effect is therefore assumed to be the same, but with a different and additional length of MSC affected by the final effluent. Therefore, this is not an improvement over the CPO Scheme in terms of water quality, only a potential deterioration. 9. Addressing objections 9.1. MSCCL SoC, April 2018 and/or correspondence 9.1.1. This section details my response to specific water quality related elements of the SoC submitted by MSSCL. These are referenced by their paragraph numbers in the SoC. 9.2. MSCCL SoC paragraph 1.4.1. Claimed objection: The proposal is inherently unsustainable, moving an existing unsatisfactory discharge from one unacceptably polluted water body to another.

BDB letter of 20 October 2016: paragraph 28. Concern that the effluent will not be treated further but will simply be transferred from Salteye Brook to the MSC. 9.2.1. Response. I have already dealt with this contention in more detail above. The objection is misconceived. The CPO Scheme does not simply transfer a problem as alleged. Rather, it is a proposal that results in achieving a satisfactory discharge based on the EA’s SIMCAT modelling and identification of solutions to tackle storm discharges. It enables the substantial improvement of a long stretch of a currently unsatisfactory water body (Salteye Brook) while also having a small positive effect on another water body (MSC). The net benefit is demonstrated by the modelling summarised in Appendix 4. 9.2.2. As I have already noted, sewage discharge treatment is based on the principle of effective dilution. By transferring the discharge to a larger body of water the effectiveness of this approach increases. From a regulatory perspective, all discharges will be within consented limits. The regulator is

satisfied that the CPO Scheme would be compliant from a water quality perspective. I agree with that position. 9.3. MSCCL SoC paragraph 1.4.1. Claimed objection: the effect of the approach that UUWL has adopted would be to further entrench an existing long-term water quality problem in the Manchester Ship Canal (MSC) caused in large part by the effects of UUWL’s discharges of treated, partially treated and untreated sewage effluent.

MSCCL SoC paragraph 6.16. MSCCL will advance a case that the effect of confirming the CPO Scheme would be to entrench the long-standing and unacceptable problem of poor water quality in the MSC 9.3.1. Response. I have dealt with these allegations in more detail above. The main issue that affects water quality in the MSC during dry weather flows is the physical structure of the MSC. As a deep, steep sided and slow-moving body of water, it would suffer water quality problems associated with stagnation even in the absence of any sewage related discharges. This is the overriding influence on water quality in the MSC during still, dry conditions. The proposed CPO Scheme has a net beneficial effect on water quality both in the Brook and the MSC itself. Furthermore, by delivering treatment within the regulatory requirements set by the EA for discharge into the MSC, United Utilities will be carrying out its obligations effectively. 9.4. MSCCL SoC paragraph 1.4.2. Claimed objection: the design of the CPO Scheme… is likely to result in an additional and direct material detrimental impact on the water quality in the MSC due to the intermittent discharge of large volumes of accumulated biological sludge.

MSCCL SoC paragraph 6.12.3. Claimed objection: a plug of sewage sludge [will be] discharged from the proposed CPO outfall on an intermittent basis and [impact] the MSC at the point of that discharge.

MSCCL SoC paragraph 8.1: Claimed objection of Flawed scheme design: MSSCL Group will adduce evidence to demonstrate that the design of the tunnel with the submerged outlet has an inherent, and significant, design flaw, caused by the very low velocity of flow in the pipe and its consequent inability to effectively self-cleanse.

MSSCL SoC paragraph 6.19.1. Claimed objection- [b] …flushing out of the accumulated sediment from the 1.2km long tunnel … will adversely impact the water quality of the MSC… 9.4.1. Response. This objection is misconceived. It is based on an assumption that there will be accumulated sludge discharged in the way suggested. This assumption is mistaken and is based on a misunderstanding of the type of effluent carried in the CPO Scheme pipe following WwTW treatment. Only minimal deposit accumulation will occur (Appendix 5). I am satisfied that there will be no water quality consequence of periodic sludge mobilisation as alleged. Therefore, I do not anticipate any deterioration in water quality. 9.5. MSCCL SoC paragraph 6.12.2. Claimed objection- a significant deterioration may occur at a level which does not in itself give rise to a lowering of the WFD status of the relevant waterbody. 9.5.1. Response. As I have demonstrated in Sections 5 and 6 of this Proof of Evidence, there will be a net water quality benefit to both Salteye Brook and the MSC. There will be no overall deterioration. Therefore, I do not consider this to be a legitimate concern. 9.6. MSCCL SoC paragraph 6.14. It is acknowledged that the effect of the CPO Scheme for Salteye Brook will be to result in an improvement in its water quality. 9.6.1. Response. The objector is correct to acknowledge that the CPO Scheme will result in an improvement to the water quality of Salteye Brook. In this regard, it is important to note that such improvement is the main regulatory driver for the CPO Scheme. However, and somewhat surprisingly, the objectors’ SoC rarely acknowledges the same. I have discussed in some detail the anticipated improvements to Salteye Brook in Section 5 of this Proof of Evidence. 9.7. MSSCL SoC paragraph 6.15. Claimed objection: [Improvement in Salteye Brook] will, however, be at the detriment of the water quality of the MSC…

MSCCL SoC paragraph 6.17. Claimed objection: [The] CPO Scheme will in fact result in a worsening in water quality in the MSC.

BDB letter of 20 October 2016: paragraph 32. Claimed objection: Concern that more stringent standards for Salteye Brook would be of benefit to the MSC, whereas UU’s proposed solution would cause ‘further deterioration’ in water quality in the MSC.

9.7.1. Response. These objections are incorrect in assuming any worsening of the water quality in the MSC. As I have demonstrated in Section 6 of this Proof of Evidence, there will be no deterioration and indeed an overall improvement in water quality in the MSC. It is also worth noting also that whilst continued discharge into Salteye Brook in compliance with a more stringent standard would improve water quality in Salteye Brook relative to the current situation, it would in fact still result lower water quality in Salteye Brook than would be achieved with the CPO Scheme. Improvement of Salteye Brook water quality is the main regulatory driver for this work for all the reasons I have explained. Hence the CPO Scheme would still be the better option. 9.8. MSSCL SoC paragraph 6.19.1. Claimed objection; [There will be] an approximate 20% reduction in the combined annual untreated spill volume into the MSC… the effect of the increase in the 1 in 5 year flow rate … is likely to negate any positive effect. 9.8.1. Response. As demonstrated in Appendix 4, this is incorrect as it only focuses on spill rate, and it ignores the fact that overall loads of contaminants will be reduced. Therefore, I do not consider this to be a legitimate concern. 9.9. MSCCL SoC paragraph 6.19.2. Claimed objection: The … screening equipment that is being provided by UUWL… will remove solid material, such as cotton buds, sanitary products, condoms etc, known as ‘sewage litter’… the removal of sewage litter only benefits the aesthetic appearance of the storm water, it does not reduce the pollutant load of the discharge… Therefore it is misleading to suggest that this would result in an improvement in the water quality of the MSC. 9.9.1. Response. This objection is based on several misconceptions. 9.9.2. The materials listed are only illustrative examples of what screening equipment will stop. Although those listed are persistent and identifiable (and so most often observed after spills have occurred), the screens will also stop the discharge of large particles of more labile organic matter (effectively aggregated faecal matter, sewage fungus, etc.) which would otherwise be discharged, but then quickly break down into smaller and therefore less visible particles before being decomposed. Therefore, the screens have a clear positive impact on water quality by arresting discharge of untreated sewage. 9.9.3. The more persistent items listed are themselves designed to absorb or retain direct human discharges, the later decomposition of which will affect water quality. The absorbent nature of most of the persistent items listed will also give rise to them becoming saturated with other organic contaminants once in the

sewage system. Therefore, these items themselves are conduits for matter that will affect water quality. 9.9.4. The items listed often are persistent because they are largely constructed of, or contain, plastics. Plastics are a significant pollutant in aquatic environments23 and their presence and physical breakdown affects water quality from the perspective of organisms living in the water, albeit not in terms of ammonia or BOD concentration. 9.9.5. Items such as those listed are also important aesthetically, as they contribute to visual pollution from a human perspective. While not a measure of water quality, this is pollution in its own right. 9.9.6. By screening outfalls, United Utilities is not only reducing its direct water quality impacts with respect to its regulatory requirements to reduce BOD and ammonia load, but is also having a positive effect on other elements of water quality and aquatic pollution more generally. 9.10. MSCCL SoC paragraph 6.20. Claimed objection: at present, the discharges received by the MSC have already passed along Salteye Brook. The flow rate of the brook allows water to air mixing which encourages some oxygen to dissolve into the water, improving its quality. The removal of Salteye Brook as an interim conduit of the discharge into the MSC therefore removes this minor beneficial effect.

BDB letter of 20 October 2016: paragraph 34. Claimed objection: concern that the effect of dilution within Salteye Brook would be lost, and that a solution to this is better treatment to improve the quality of final effluent and increased storm storage capacity would be more appropriate. 9.10.1. Response. The suggestion that Salteye Brook provides effective dilution and aeration of effluent is flawed. 9.10.2. I have considered the potential for oxygen mixing into Salteye Brook in Section 4.3 above. In summary, there is an initial minor oxygenating benefit as Salteye Brook passes over a small reach of steep gradient immediately downstream of the Eccles WwTW discharge. However, beyond this, Salteye Brook is a very slow-moving backwater of the MSC, flowing along a section of channel that was formerly occupied by the River Irwell. Therefore, the channel is much larger than the brook would naturally occupy, which means that the flow

23 See for example Gill, V. (12 March 2018) “Microplastics are ‘littering’ riverbeds”, citing a study on rivers in the Manchester region. http://www.bbc.co.uk/news/science-environment-43363545

is smooth with very little turbulence to facilitate mixing or aeration to elevate oxygen levels. 9.10.3. Decomposition of organic matter within this channel is likely to be removing oxygen more rapidly than it is being added. Therefore, its ability to improve water quality is severely compromised and, as I have suggested, there may even be a further reduction in quality. 9.10.4. Furthermore, if a discharge into Salteye Brook is retained, even with treatment to higher standards, this would still lead to lower water quality in Salteye Brook than if it were removed entirely as proposed by United Utilities. 9.11. MSCCL SoC paragraph 7.22. The treatment alternatives considered by MSCCL group…

BDB letter of 20 October 2016: paragraph 39. Claimed objection: concern that discharge of storm sewage directly into the MSC will also detrimentally affect its biological and biochemical health, contrary to the WFD principle of no deterioration and hindering achievement of Good Ecological Potential. 9.11.1. Response. Each of the alternatives raised by MSCCL has been considered from a water quality perspective in Section 8.3 above. That section describes and demonstrates why none of them result in a water quality improvement relative to the CPO Scheme. Indeed, most alternatives result in potential water quality deterioration when compared to the current situation. 9.11.2. The earlier concern raised in the BDB letter of 20 October 2016 contradicts most of the proposed alternative options presented by MSCCL in their SoC and summarised in Section 8.3, four of which propose discharge of storm overflows directly into the MSC, and two of which also propose discharge of final effluent directly into the MSC. 9.12. MSCCL SoC section 9. Claimed objection: unsustainable development not in the public interest.

MSCCL SoC paragraph 9.3. Claimed objection: …the MSC too has long been, and remains, in an unacceptable state, and has failed and continues to be unable to meet the legislative target for its own improvement, and this itself is a very important consideration in the public interest.

MSCCL SoC paragraph 9.4. Claimed objection: the means by which the improvement to Salteye Brook is proposed to be achieved, by diverting the

unacceptable discharges from one watercourse to the other, will be largely successful in respect of Salteye Brook, but does nothing to address the underlying problem, which is the quality of discharges from Eccles WwTW into the receiving watercourses. UUWL’s proposals amount to treating the MSC as an open sewer. 9.12.1. Response. I have already dealt with and identified the improvements in water quality that the CPO Scheme will deliver for both the Salteye Brook and the MSC. Moreover, as set out in Section 3.3 above, the major problems associated with water quality in the MSC are not due to inputs from Eccles WwTW, with which the volume of water in the MSC is more than adequate to deal, but rather the physical structure of the MSC. It is the MSC’s physical structure that is the overriding influence on water quality, particularly during dry, still periods. For this reason, it would be difficult to justify substantial additional expenditure on further refining sewage treatment if the structural issues associated with the MSC are not addressed. Any further polishing of WwTW effluents would be utterly negated by the influence of MSC structure on water quality during normal summer months, when still and dry conditions might be expected. I therefore fundamentally disagree with MSCCL’s position in this regard. 9.13. BDB letter, 20 October 2016. 9.13.1. Items below relate to specific environmental concerns raised in BDB’s letter of 20 October 2016, at paragraphs 28 to 40. Several were duplicated in the Final SoC, and have therefore been addressed above. Others have not been reproduced in the Final SoC, and therefore I assume that they are no longer being pursued as part of their case. However, for completeness these are addressed in turn below. 9.13.2. BDB letter Paragraph 29. Concern that the current EA discharge permit for Eccles WwTW is less stringent than for Davyhulme WwTW. 9.13.2.1. Response. The attempt made at comparison with Thames Water’s Deephams WwTW discharge consent in East London is flawed. Deephams WwTW effluent discharges not into the River Lee, as stated in the concern, but into Salmons Brook, a tributary of the River Lee. The mean daily flow of Salmons Brook (including its tributary Pymme’s Brook) is 54 Ml/d upstream of the works24, and Deephams WwTW is being

24 Sum of mean flow data in the National River Flow Archive quoted for Salmon Brook at Edmonton (0.16 m3/s) and Pymme’s Brook at Edmonton Silver St (0.465 m3/s), accessed 29 March 2018.

upgraded to enable a discharge of up to 497 Ml/d25. Salmons Brook flows into the River Lee, whose mean daily flow downstream of the confluence is currently 485 Ml/d26. So the dilution afforded by the River Lee approaches 90% of the combined flow from the WwTW and the flow immediately upstream. In comparison, Eccles WwTW (mean daily discharge 41 Ml/d) and Davyhulme WwTW (mean daily discharge 322 Ml/d) discharge into the MSC with a mean daily discharge upstream of 1680 Ml/d. Therefore, to state that the discharge is comparable with the MSC is incorrect. The level of dilution afforded by the MSC represents over 4000% of the discharge from Eccles WwTW and over 500% for Davyhulme. 9.13.3. BDB letter Paragraph 30. Concern that the treated effluent has discharge permit of 89.337 m litres per day (Ml/day) and a suspended solids permit of 45 mg/l, giving up to 89 kg per day of solid matter requiring dredging. 9.13.3.1. Response. Taking the mean values for suspended solids concentration and discharge volume for Eccles WwTW gives a daily suspended sediment load entering the MSC of 420.9 kg, which is equivalent to 1.9% of the load being carried from upstream27. In the extremely unlikely event that the WwTW could discharge continuously to its suspended solids permit of 45 mg/l, this load would increase to 4004.6 kg/day. However, even this extreme input would still constitute less than 5% of the loading in the MSC. The assumption that all of this load will fall to the bed of the MSC and require dredging is flawed; much will remain in suspension. Additionally, the proposal is unlikely to result in a change in the amount of suspended solids entering the MSC from Eccles WwTW, as they are currently being discharged via Salteye Brook, so the proposal would not impact on any dredging requirements required for the MSC. 9.13.4. BDB letter Paragraph 38. Concern that the proposal contradicts the principles of the WFD. 9.13.4.1. Response. The basis of the purported concern is a contention that the proposal contradicts the principles of the WFD by:

25 Ollett E. (2013) Deephams STW AMP5/6 Quality Upgrade - Phase 1. UK Water Projects 2013, pp132-136. www.waterprojectsonline.com

26 Mean flow data in the National River Flow Archive for River Lee at Lea Bridge, accessed 29 March 2018.

27 Based on Environment Agency monitoring data at Barton Locks, 2014-17.

 Not taking measures to prevent deterioration of the current water body status, and  Not attempting to improve water quality in order to achieve Good Potential. 9.13.4.2. I have addressed why these contentions are unjustified throughout my Proof of Evidence. The concern appears to be specific to the MSC, and not to consider the large positive effect on Salteye Brook. Furthermore, while I am confident that water quality in the MSC will be improved, I repeat the fact that currently the key issue with the MSC is not inputs but its physical structure.