“Why is the water quality in the River Doe Lea so poor?”

Dissertation submitted as part requirement for the Degree of Master of Science in Urban Water Engineering and Management

By: Mark Stevens

Supervisor: Prof. David Lerner

The University of Sheffield Department of Civil & Structural Engineering September 2011

Declaration:

Mark Stevens certifies that all the material contained within this document is his own work except where it is clearly referenced to others.

______

ii ABSTRACT:

STEVENS, M. 2011. Why is the water quality in the River Doe Lea so poor? MSc Urban Water Engineering and Management Dissertation, Department of Civil and Structural Engineering, University of Sheffield

The Doe Lea River has a long history of pollution issues which once earned it the reputation of the most polluted river in Europe. Water quality has succumbed to the pressures of mining heritage, industry, agriculture, urban growth and major highways which dominate the catchment. The catchment has a poor chemical and biological classification status with the Environment Agency and ecological statues varies between poor and bad. Conditions of poor flow are often observed, which intensify water quality issues.

In order to determine the reasons for the degradation of surface water quality, a project has been devised to take a snapshot of the water chemistry. Fifty water samples were collected simultaneously across the whole catchment and repeated for each season of the year. Analysis of these samples has developed understanding of pressures and influences that are contributing to water quality degradation. Via a mass balance analysis, it has been possible to locate particular areas of concern, determine sources and quantities of pollution and devise land management options to alleviate pollution stresses.

Significant pressures have been determined as the result of diffuse runoff from agricultural and urban landuses, mine related discharges and discharges from sewage treatment works. Considerable influxes of nitrate and phosphate provide the greatest water quality stresses and poorest quality waters are located in the lower urbanised reaches of the catchment. Metalliferous discharges from ex-colliery sites are observed in numerous locations and industrial polluters are pinpointed. Solutions are suggested and further study identified to improve the water quality in the river to meet the water framework directive targets of 2015.

Key words: Doe Lea, river, analysis, catchment, water quality, diffuse pollution, mine drainage, nitrates, phosphates, sampling, mass balance, landuse

iii ACKNOWLEDGEMENTS:

Thanks must go to my dissertation supervisor, Prof. David Lerner whose guidance and input has enabled me to complete this project. Also the assistance of Andrew Fairburn in the University laboratories has been invaluable both in analysing the samples and teaching me the use of the water quality analysis equipment.

A special acknowledgment must go to Tina Bardill of the National Trust without whose help the project would not run. Credit for organisation and co-ordination of the sampling events must go to Tina who has also proved an invaluable resource of local knowledge.

Thanks are also extended to the fifty volunteers that joined in with each Doe Lea Dip. Without their time, a snapshot of the catchment simply would not be possible.

iv CONTENTS: Content: Page Number:

Abstract iii Definition of terms vii Summary of figures viii

1.0 Chapter of introduction 01

1.1 An introduction to the Doe Lea River catchment 01

1.2 Aims and objectives of the project 03

1.3 Water quality in the Doe Lea and the WFD standards 04

1.4 What knowledge is available from previous studies of the Doe Lea? 06

1.5 What parameters are being investigated to determine water quality? 10

1.6 Potential problems and anticipated errors in the data 10

1.7 Conceptual interactions 12

2.0 Methodology of data collection and analysis 14

2.1 The Doe Lea catchment and sampling locations 14

2.2 Times and dates of data collection 15

2.3 Laboratory techniques and sample analysis 16

2.4 Quality of and confidence in collected and analysed data 17

2.5 Hypothesis and expectations of sampling data 18

2.6 Representation of collected data 18

2.7 Additional field data collection 19

3.0 Analysis of Doe Lea River samples 20

3.1 Comparison of samples with EA river monitoring data 20

3.2 Agricultural pollution in the Doe Lea 22

3.3 Mining Influences on the Doe Lea Catchment 27

3.4 Industrial influences on the Doe Lea 31

3.5 Urban influences on the Doe Lea 31

3.6 Further analysis of the catchment, flow and mass balance 34

3.7 Defining catchment precipitation 36

3.8 Land use in the Doe Lea 37

3.9 Soil types within the catchment 40

3.10 Description of catchment geology 44

3.11 Summary of artificial contributions and abstractions 45

3.12 Conceptual interactions of river and groundwater 47

3.13 Estimations of flow 48

3.14 Flow estimations for April analysis 48

3.15 Flow estimations for the July analysis 49

3.16 Analysis by method of mass balance 53

v 3.17 Effects of seasonal variability on water quality in the Doe Lea 59

4.0 Discussion 61

4.1 The mass balance analysis and finding of interest 62

4.2 Seasonal variability of the April and July dips 66

4.3 Expectations of November and February dips 66

4.4 Problems encountered with techniques, conditions and findings 67

4.5 How can the project be improved for future dips? 69

4.6 Further study 70

5.0 Conclusions 72

5.1 Summary of suggested changes to future sampling 75

5.2 How do the project results compare to initial hypotheses? 75

5.3 Why is the water quality in the Doe Lea so poor: A final summary 76

6.0 References 79

Appendix A: 85

A.1 Analysis of water samples for April sampling 85

A.2 Flow estimation for April Sampling 90

A.3 Laboratory results for April sampling 91

A.4 Mass balance results for April sampling 92

A.5 Analysis of water samples for July sampling 97

A.6 Flow estimation for July Sampling 102

A.7 Laboratory results for July sampling 103

A.8 Mass balance results for July sampling 104

A.9 Comparison of April and July sampling results 109

Appendix B: 111

B.1 Detailed map of the North half of the Doe Lea Catchment 111

B.2 Detailed map of the South half of the Doe Lea Catchment 112

Appendix C: 113

River sediment monitoring and dioxin analysis in the Doe Lea: A literature 115 survey of Environment Agency studies between 1991 and 1998 117

Appendix D: 119

D.1 Enlarged map of landuse in the Doe Lea Catchment 119

D.2 Plot of additional known land users across the catchment 120

vi DEFINITION OF TERMS:

BOD Biochemical Oxygen Demand BPEO Best Practice Environmental Option BETP Biological Effluent Treatment Plant CBC Chesterfield Borough Council CEH Centre for Ecology and Hydrology CIWEM Chartered Institute of Water & Environmental Management CoGAP Code of Good Agricultural Practice CSC Catchment Science Centre DEFRA Department for Environment, Food & Rural Affairs DNRA Dissimilatory Nitrate Reduction to Ammonium DO Dissolved Oxygen EA Environment Agency GIS Geographical Information System HOST Hydrology of Soil Types MAFF Ministry of Agriculture, Fisheries and Food NERC Natural Environment Research Council ND Nitrate Directive NRA National Rivers Authority NRFA National River Flow Archive NSA Nitrate Sensitive Area NSRI National Soil Research Institute NT National Trust NVZ Nitrate Vulnerable Zone SEPA Scottish Environmental Protection Agency SS Suspended Solids SSSI Site of Specific Scientific Interest STW Sewage Treatment Works SUDS Sustainable Urban Drainage System USEPA United States Environmental Protection Agency UWWTD Urban Waste Water Treatment Directive WFD Water Framework Directive

vii

SUMMARY OF FIGURES:

Chapter One: Figure 1.1 Map of the Doe Lea Catchment in Derbyshire, UK Figure 1.2 Assessment of the Water Framework Directive ecological status within the Doe Lea Catchment Figure 1.3 Representation of Environment Agency data for current water quality against the EU Water Framework Directive standards for 2015 Figure 1.4 Representation of river dioxin concentrations Figure 1.5 The remains of Coalite Chemicals in 2011. Figure 1.6 Rainfall maps displaying the percentage of average rainfall across Britain for the months of March, April, May and June 2011 Figure 1.7 Presentation of conceptualised interactions within the catchment

Chapter Two: Figure 2.1 Map of the 50 sampling sites within the Doe Lea Catchment

Chapter Three: Figure 3.1 EA values for phosphate and nitrate against samples from the Catchment Science Centre Figure 3.2 Comparison of results with published results from the EA Figure 3.3 EA classifications for Phosphate and Nitrate in UK rivers Figure 3.4 Plot of EA data showing reduction in N & P in the River Doe Lea over the past 5 years Figure 3.5 Doe Lea N & P against the EA classification Figure 3.6 A plot of the mining influences in the Doe Lea Catchment Figure 3.7 Concentrations of heavy metals at sampling point 33 Figure 3.8 Effects of nitrification in Pools Brook after an influx of ammonium at Long Duckmanton STW. Figure 3.9 A Conceptual interaction of pathways of pollutants to the river Figure 3.10 Rainfall estimates over the Doe Lea catchment Figure 3.11 Maps of the land use in the Doe Lea catchment Figure 3.12 Distribution estimate of precipitation for a range of land uses

viii Figure 3.13 Plot of soil types in the catchment as described by the NSRI Figure 3.14 Plot of HOST soil types in the catchment Figure 3.15 Geological features of the Doe Lea Catchment Figure 3.16 Plot of known discharges/abstractions to/from the Doe Lea Figure 3.17 Estimation of flow in the catchment for the April analysis Figure 3.18 Example Cross-section of the river flow measurement Figure 3.19 Estimation of flow in the catchment for the July analysis Figure 3.20 Comparison of measured flows against estimated flows Figure 3.21 Graph of mass balance between locations 28 and 34 Figure 3.22 Table of increase in concentration and mass flux at points 28 and 34 Figure 3.23 Graphs of metals and nitrogen in Pools Brook Figure 3.24 Plots of mass flux for each sampling location

Chapter Four: Figure 4.1 High-risk areas from Doe Lea catchment preliminary study

Chapter Five: Figure 5.1 A summary of conclusions compared to initial hypotheses Figure 5.2 Most pressured sub-catchments from Doe Lea Dip samples Figure 5.3 Concluding table of key drivers of water quality degradation

Appendix A:

Figure A.1 Plots of Al, NH4, BOD and Cd concentrations for April Figure A.2 Plots of Cl, Cr, Cu and Fe concentrations for April

Figure A.3 Plots of Pb, Mn, Ni and NO3 concentrations for April

Figure A.4 Plots of pH, P, SO4 and Zn concentrations for April Figure A.5 Plot of estimated flow in the catchment for April Figure A.6 April laboratory results for inorganics and metals Figure A.7 Graph of April mass balance on the main Doe Lea River (1/2) Figure A.8 Graph of April mass balance on the main Doe Lea River (2/2) Figure A.9 Graph of April mass balance in Pools Brook (1/2) Figure A.10 Graph of April mass balance in Pools Brook (2/2) Figure A.11 Graph of April mass balance in Hawke Brook. Figure A.12 Plots of Al, NH4, BOD5 and Cl concentrations for July Figure A.13 Plots of Cr, Cu, Fe and Pb concentrations for July

ix Figure A.14 Plots of Mn, Ni, NO3 and pH concentrations for July Figure A.15 Plots of P, Sr, SO4 and Zn concentrations for July Figure A.16 Plot of estimated flow in the catchment for July Figure A.17 July laboratory results for inorganics and metals Figure A.18 Graph of July mass balance on the main Doe Lea River (1/2) Figure A.19 Graph of July mass balance on the main Doe Lea River (2/2) Figure A.20 Graph of July mass balance in Pools Brook (1/2) Figure A.21 Graph of July mass balance in Pools Brook (1/2) Figure A.22 Graph of July mass balance in Hawke Brook Figure A.23 Graph comparing results for April and July in the Doe Lea River Figure A.24 Graph comparing results for April and July in Pools Brook

Appendix B: Figure B.1 Detailed map of the North half of the Doe Lea Catchment Figure B.2 Detailed map of the South half of the Doe Lea Catchment

Appendix C: Figure C.1 Pollution from BTEP pipes at Coalite Chemicals in Derbyshire UK Figure C.2 Dioxin concentrations in the Doe Lea downstream of Coalite Figure C.3 Locations of dioxin measurements between 1991 and 1998 Figure C.4 Dioxin concentrations in the River Doe Lea between 1991 and 1998

Appendix D: Figure D.1 Enlarged map of the combined landuse in the Doe Lea Catchment. Figure D.2 Detailed plot of additional known land users across the catchment

x 1.0 CHAPTER OF INTRODUCTION:

1.1 AN INTRODUCTION TO THE DOE LEA RIVER CATCHMENT:

The Doe Lea Catchment is located in Derbyshire, England. It lies 7km east of Chesterfield and covers an approximate area of 69.7km2 (Marsh & Hannaford, 2008, CEH, 2011). The River Doe Lea stretches 18km from its source near Tibshelf in the south of the catchment to its end point where it discharges into the River Rother to the north. The river is fed by naturally occurring land drainage and springs on the peripheries of the catchment. The two main tributaries to the river, Pools Brook and Hawke Brook, each cover approximately 5km and discharge into the lower reaches of the River Doe Lea. A map of the catchment is illustrated below in Figure 1.1.

Figure 1.1: Map of the Doe Lea Catchment in Derbyshire, UK

- 1 - The Doe Lea is located on the southernmost part of the River Don catchment which drains through the Environment Agency (EA) assigned Humber river basin district (EA 2004, Lezartza-Artza et al 2009). It is situated in a predominantly rural catchment with other mixed urban landuse including mining, industry and major highway routes. Landuse in the upper catchment is mainly agricultural, with some industry on the periphery and redundant collieries scattered near settlements. The lower catchment shifts to more urbanised landuse. Industry, mining and landfill still have a strong presence, though agriculture dominates the landscape. The largest two settlements by the river, Bolsover and Staveley, are located in the middle and lower reaches of the river respectively.

The Doe Lea catchment has a long history of water quality problems which relate to its land uses and aggressive mining practices of the 20th century. In the 1990‟s, the river was described as being the most polluted in Europe (Skinner, 1992; Schoon, 1994). Although this was due to a single pollution leak event, the long term stresses on the catchment from the coal mining industry have resulted in a trend of degraded water quality. There is also a history of poor flow conditions within the river and this only acts further in the degradation of the ecology of the watercourse (Gustard et al, 1992). The mean annual flow of the river at its point of discharge to the Rother is

-1 0.572m3s with mean total annual rainfall of 714mm and runoff equating to 37.4% of total rainfall across the catchment (Marsh & Hannaford, 2008).

This is not the first attempt to study the characteristics of water quality in the Doe Lea. Other studies have previously been undertaken and the Environment Agency has had a long involvement with recording flow, chemical and biological quality and ecological values of the river (EA, 2011a, CEH, 2011). These studies have been of much smaller scales than the one undertaken in this investigation as detailed data has only been recorded in a few locations along the river. However, numerous important water quality parameters have been recorded and are widely available from EA sources. This investigation is designed to build upon previous knowledge and develop a thorough understanding of the catchment, its land use and its water quality; ultimately defining the types and sources of major pollutants.

- 2 - 1.2 AIMS AND OBJECTIVES OF THE PROJECT:

The aim of the project is to develop a better understanding of the water quality within the Doe Lea catchment. It is hoped that by taking 50 simultaneous samples along the course of the river, a picture of the water quality issues can be developed. If significant quality issues are seen, the spatial variation of the sampling should provide a better idea of the source of pollution and its integration with the watercourse. This will help extend the understanding of landuse practices in the catchment and help implement new techniques to responsibly manage landuse in the region. By establishing the sources of pollutants via the sample collection and analysis, areas of particular interest can be further investigated. The aim is to produce a summary of contributors to the degradation of water quality in the Doe Lea and present these to the National Trust to aid implementation of techniques to attenuate the pollution sources. Successful modelling of this catchment could allow application of a model on other similar locations with similar water quality problems.

In order to realise the aim of the project, a number of objectives have been defined to contribute to the overall knowledge of the catchment. These are:

o To collect 50 individual samples at various points in the river simultaneously on four occasions over a year (only two will fall within the timeframe of this paper) o Complete laboratory analysis of the samples and present these in a format that will allow data to be easily interpreted by a range of non-educated individuals. o Visually analyse the dataset for trends and significant changes in concentration of pollutants. Identify problematic locations and attempt to locate sources of pollution and potential barriers or remediation methods. o Estimate the flow in the catchment and interactions with landuse, runoff, groundwater and artificial discharges. o Complete an analysis of mass balance between river reaches and verify influence of non-point source pollutants as well as point sources. o Discuss the results obtained and suggest landuse management options to improve water quality in the River Doe Lea.

- 3 - 1.3 WATER QUALITY IN THE DOE LEA AND THE WATER FRAMEWORK DIRECTIVE TARGET STANDARDS:

The Water Framework Directive (WFD) is a European initiative passed to encourage better management, conservation and restoration of river and waterways. The legislation, which was introduced in 2000, requires rivers and coastal waters to achieve ‘good chemical and ecological status for surface waters and good status for groundwater in terms of quality and quantity by 2015’ (Water UK, 2011). The Doe Lea has a long history of water quality problems and reaching this target will require greater investigation and efficient land management. The Environment Agency (2011b) have classified the catchment as ranging from „good‟ to „bad‟ with regard to its ecological status (figure 1.2). However, approximately 80% of the river and its tributaries have been rated „poor‟ or „bad‟ in terms of ecological status. A representation of this data is displayed in figure 1.2 below which highlights the areas of particular concern within the catchment:

Figure 1.2: Assessment of the Water Framework Directive ecological status within the Doe Lea Catchment (Data from Environment Agency, 2011b)

- 4 - Although the WFD target is installed at 2015, the EA (2011b) has predicted the Doe Lea river will only reach these water quality standards by 2027 as ‘it is considered technically unfeasible or disproportionately expensive to otherwise achieve’ (Catchment Science Centre, 2009; EA, 2011b). The issues seen in the Doe Lea are not unique. There is a common trend through the remainder of the Humber river basin of poor water quality for the duration of the watercourse. The lower reaches of the Humber basin are also highly urbanised with a long tradition of mining, agriculture and heavy manufacturing industry. The pressures of the regions industrial history have produced a net degradation of water quality within the local river systems. Of 78 river water bodies analysed by the Environment Agency, all 78 are „artificially or heavily modified‟ (EA, 2011c). The EA has defined the main pressures as ‘point source discharges from water industry sewage works and storm discharges’. This is in addition to the known problems with ‘diffuse pollution from agriculture and physical modification due to urbanisation of the landscape’ (EA, 2011c).

The WFD targets to improve quality within river bodies in the UK to achieve „good‟ status. The extent of the problem is evident when current EA water quality data is analysed against the WFD „good‟ to „bad‟ scale. For the Don and Rother, the recipients of flow from the Doe Lea and its tributaries, the proportion of river reaching „good‟ status is very low. Only 8% reaches „good ecological status‟ and 25% for „good biological status‟. The chemistry of the water bodies scores higher, though much work is still to be done to reach the WFD targets by 2015. A summary of the current extent of the problem is included in figure 1.3 below and populated with data from the Environment Agency (2011c).

Water bodies in Don & Rother catchment Percentage achieving condition Good ecological status 8% Good chemical status 74% Good ecological and chemical status 8% Good biological status 25% Poor biological status 38% Bad biological status 13%

Figure 1.3: Representation of Environment Agency data for current water quality against the EU Water Framework Directive standards to be met by 2015 (EA, 2011c).

- 5 - The quality of groundwater is also a concern within the region. It is significantly stressed within the Doe Lea catchment due to the effects of widespread mining and contamination with diffuse nitrates and pesticides (EA, 2011c). There are procedures in place to reduce the effects of polluted groundwater such as pumping mine water into balancing ponds specially constructed for this purpose. However, the National Trust have raised questions over its efficiency. In the lower reaches of the Humber catchment, large quantities of groundwater are abstracted for drinking water uses. This has been known to have a detrimental effect on river flows by lowering the water table and reducing contributions to rivers from groundwater.

1.4 WHAT KNOWLEDGE IS AVAILABLE FROM PREVIOUS STUDIES OF THE DOE LEA CATCHMENT?

There is a limited variety of literature on the Doe Lea River and its water quality issues. Some analysis has been undertaken on the river by the Environment Agency, though this has progressively diminished to the minimum level that is monitored today. Notable prior water quality issues in the area also relate to agriculture, industry and land management. In a prior study, Jarvie et al (2000) stated pressures emanate from ‘abandoned mines, particularly to the west and trade discharges in the east of the catchment into the River Doe Lea’.

As already discussed, the water quality within the Doe Lea River and its tributaries has been challenged for decades. The issues within the catchment perhaps reached their peak in 1992 when dioxin pollution labelled the river the ‘most polluted river in Europe’ (Schoon, 1994).

The discovery of a significant increase in quantities of dioxin in the river triggered an in-depth investigation into water quality. It was found the record levels of dioxins in the river were contributed by industrial company Coalite Chemicals, which were involved with ‘coal, coking and associated chemical manufacturing’ (Jarvie et al, 2000). At is peak in 1992; Schoon (1994) reported that the river had ‘the world's highest levels of dioxins, 27 times greater than the next most polluted watercourse’.

- 6 - The source of the dioxin pollution at Coalite is located in Shuttlewood adjacent to the River Doe Lea. The plant produced a variety of chemicals from coal by-products mined in the local vicinity. The National Rivers Authority undertook further investigations into dioxin concentrations in the river. Schoon (1994) continued in his report to state that ‘upstream of the Coalite Chemicals plant, dioxin levels in the sediments were at 2 ppm. Just below it the authority said they were 10,000 times higher at 20,269 ppm’. This problem transferred down stream into the rivers Rother and Don, where dioxin levels of 300 ppm were recorded 13 miles from the source point (Schoon, 1994).

Dioxins are a by-product of chemical production and are extremely damaging to human health in large quantities (USEPA, 2011). When discharged from Coalite, they naturally adsorbed to the fine-grained sediments in the bed of the River Doe Lea. Huntley et al. (2001) discussed how the Best Practicable Environmental Option (BPEO) was ‘found to be one of non-intervention for the Doe Lea and Rother’. They concluded that dispersion and dilution has rapidly decreased the concentration of pollution, though there still remains ‘significant concentrations within the sediments of the South Yorkshire river network’. A paper by Scott Wilson (1998) accepted the relative merits of a method of non-intervention, however favoured a method of river dredging and landfill disposal. They suggested it offered the ‘most rapid progress, lowest overall risk, lowest cost solution and all with acceptable risks’ A representation of the reports findings is included below in figure 1.4 to show the historical levels of dioxin concentrations in the Doe Lea and connected rivers:

Km from Location River Oct-91 Mar-93 Mar-95 Feb-96 Feb-97 Nov-98 source Bolsover Doe Lea Upstream 10 9 18 11 15 16 Buttermilk Doe Lea 0 64000 45300 1200 550 290 350 Lane Netherthorpe Doe Lea 4.4 26000 12300 450 330 540 360 Renishaw Rother 9 1500 300 - 79 53 97 Canklow Rother 27.1 1700 426 - 93 96 360 Rotherham Don 29.3 570 - - 180 310 140 Kilnhurst Don 37 - - - 110 140 110 Thorne Don 74.9 - - - 9 8 9

Figure 1.4: Representation of river dioxin concentrations (ng/kg iTEQ) after Huntley et al (2001) using source data from the Environment Agency’s monitoring programme.

- 7 - It is also reported by Huntley et al. (2001) that there was a major flood in the Doe Lea catchment in 1995, spreading much of the contaminated water and sediment onto the surrounding shallow farmland adjacent to the river. In the literature, there is a lot of discussion relating to agricultural difficulties as a result of this flood pollution. Skinner (1992), reported how polluted farm land had resulted in the closure of local farms as milk production showed signs of the toxins. The effects of pollution in the river were now attracting attention and a new target to improve water quality was installed.

Lilley (2002) stated how ‘dioxin is probably the most toxic synthetic chemical known to science and the bulk of our exposure to dioxins is through the food chain (around 98%)’. This clearly shows that water quality problems in the Doe Lea catchment have the potential to affect a much wider population and community. This comment is supported by Lake et al (2005) whose study looks at the effect of river flooding on dioxin levels in soil and grass. One of its focus rivers was the Doe Lea where they found a far higher dioxin concentration in flood-prone land compared to non flood- prone sites. They concluded that the flooding of pastureland is ‘directly responsible for observed elevations in dioxins in milk produced from these sites’. If there remains a high concentration of pollutants in the river, then potentially this could be a recurring problem throughout the flood-prone areas of the catchment.

The industrial units at Coalite causing the dioxin pollution in the 1990‟s have now ceased operation and hence the pollution from these sources has ceased also. However, impacts from agriculture, such as nitrogen and phosphorous pollution are notably having a detrimental effect on the Doe Lea water quality. Defra (2004) has recently researched the role agriculture plays on diffuse pollution in ground and surface waters. Runoff from agricultural areas in the catchment can collect organic material with high BOD or nutrient content. This is supplemented by agricultural fertilisers which cause overstimulation of aquatic plants, reducing the dissolved oxygen concentration in the water and ultimately reducing the ecological value and quality of the river (Mueller & Helsel, 1999).

Defra (2004) estimate that 60% of nitrogen in surface water results from agriculture and 32% comes from sewage treatment works. In a similar study, Naismith et al.

- 8 - (1996) found that intensely farmed land in the Torridge Catchment, Devon, consistently delivered much poorer water quality than non-intensely farmed land with respect to BOD, dissolved oxygen, suspended solids and nutrients. There is clearly the scope to reduce the production through agriculture by enforcing better land management. Nitrogen and phosphorus levels will be examined as part of this investigation. If they are found to excessively contribute to water quality decline in the catchment, better land, water and soil management initiatives can be developed and enforced. Thus ultimately achieving the project goal of improving water quality in the River Doe Lea.

There are likely to be future pressures on the river as a result of redevelopment plans in the area. The now derelict Coalite Chemicals plant is being targeted for redevelopment to site a new industrial estate (Hopkinson, 2008). With the proximity to the river and the increased potential for diffuse pollution entering the watercourse via runoff, land uses such as this will increase the pressure on the Doe Lea catchment. This therefore adds justification for the need of a project of this type to be undertaken in the Doe Lea Catchment.

A more detailed report on the sediment and dioxin pollution in the Doe Lea is included in appendix C. This is compiled with Environment Agency, National River Authority and Consultancy papers. It details the methods of remediation suggested and plots the most polluted areas and the timeframe that the dioxin pollution affected the region.

Figure 1.5: The degraded remains of Coalite Chemicals in 2011 after its closure a decade earlier.

- 9 - 1.5 WHAT PARAMETERS ARE BEING INVESTIGATED TO DETERMINE WATER QUALITY?:

The laboratory methods used to obtain the concentrations of components within the water samples allow a large range of organics, inorganics and metals to be determined. This covers a wide spectrum of both pollutants and naturally occurring substances within river waters. A full list of the compounds tested is included in Appendix A for reference; with the most significant parameters being discussed throughout the report. A full description of methods of analysing the concentrations of each compound is included later in ‘laboratory techniques and analysis of field samples’.

The investigation was designed to analyse as appropriate a range of information as possible to best decipher the water quality within the catchment. This included all the mainstream pollutants that would be expected to be analysed (nitrates, phosphates, ammonia, BOD5, chloride, sulphates, pH, metals etc). Suspended solids were not analysed mechanically and instead the turbidity of samples was visually inspected and noted. In addition to the above, a scan of poly-aromatic hydrocarbons (PAH‟s) was conducted and a scan for pesticides was completed for the July dip. The change was a result of inconclusive results returned from the PAH analysis. The readings showed no deviation and all readings were returned as <0.02mg/l which was as low as the equipment could measure. Hence this was changed for the second analysis to a pesticide scan to reveal the extent of diffuse pollution problems in the catchment due to agricultural pesticide application

1.6 POTENTIAL PROBLEMS AND ANTICIPATED ERRORS IN THE DATA:

There are many potential problems with undertaking a project such as this. Below is a summary of the problems that will have the greatest effect on the quality of the results:

o The volunteers collecting the samples have only been given basic training. They do not fully understand the requirements of the samples and so to the

- 10 - best of our abilities, the volunteers have been taught how to capture the most effective water sample. It is a concern that the samples may not be collected at exactly the locations specified. They may also have sediment or contamination of some kind. Precautions have been taken to ensure the quality of the samples by tutoring the volunteer collectors, but ultimately it was up to them to ensure the samples were fair and true representations of the River Doe Lea watercourse.

o The time of collection was also important. These dates were pre-determined and designed around the spreading of fertilisers etc. As the application of fertilisers is dependant on crop growing seasons, compensation for this has been made in the sampling plan. This was a major driver to the year long programme to see the effects of the agricultural activities in their busiest seasons of spring and summer compared to their quietest of autumn and winter.

o The sampling is dependent on the weather conditions prior to the sampling dates. The UK has experienced its driest spring since records began (BBC, 2011) with England receiving just 25% of average rainfall according to the MET Office (2011a). Whereas this didn‟t noticeably affect the flow and concentrations of pollutants in the April sampling; it had a big impact on the July samples. Four of the sites on the periphery of the catchment were dry for this analysis and many more had low flow so the full 50 samples could not be collected. Due to this reduced flow in the river, higher concentrations of pollutants were seen in some locations potentially having a bias effect on the analysis. During March and April, the average rainfall over the catchment was approximately 20% of the average between 1971 & 2000 (MET Office, 2011). The months of May and June were also below usual levels, each of which received approximately 75% of usual rainfall as shown here in figure 1.6:

- 11 -

Figure 1.6: Rainfall maps displaying the percentage of average rainfall across Britain for the months of March, April, May and June 2011. All information courtesy of the Met Office, 2011 © Crown copyright [2011], the Met Office.

1.7 CONCEPTUAL INTERACTIONS:

In order to define the causes for poor water quality in the catchment, it is important to conceptualise how these interactions relate and cause the issues. Therefore a conceptual model has been developed in order to think about and visualise the relationships between pollutant sources, their pathways and their receptor which is ultimately the river. The flowchart below in figure 1.7 is a presentation of the expected interactions highlighting the main pollutant sources, their pathways to the river and means of discharge to the river (point or non-point).

- 12 -

Figure 1.7: Presentation of conceptualised interactions within the catchment that define the sources, types, implications and impacts of pollutants and there pathways from source to receptor

- 13 - 2.0 METHODOLOGY OF DATA COLLECTION AND ANALYSIS:

2.1 THE DOE LEA CATCHMENT AND SAMPLING LOCATIONS:

Initially, the project area has been divided up into five sub-catchments draining into the main Doe Lea River. Over the course of the river and its five sub-catchments, 50 sampling points have been allocated. This was done to gather as wide a spread of data over the catchment as was feasible. Applying so many sampling sites across the study area allows a thorough analysis to be undertaken and pollutant sources to be pin-pointed to individual river reaches. The locations at which samples were collected and the division of the catchment is illustrated here in figure 2.1.

Figure 2.1: Map of the 50 sampling sites within the Doe Lea Catchment [An enlarged map is included in Appendix B for reference]

- 14 - Upon sourcing the river reaches that are of most concern, individual mass-balance analysis can be undertaken to investigate what processes are occurring between the two sample points. This can be followed up by investigation of all discharges into the river at that location and tracing pollutant types back to their sources. Thus, most effectively enabling the management group to distinguish and remediate pollutant sources into the watercourse. Non-point discharges, such as agricultural runoff which enters the river over a large area and not just a pipe outfall for example are harder to establish. This is why the mass-balance method of analysis will be the most sensible solution to investigate problem areas and should provide the most accurate description of the processes occurring within the river.

2.2 TIMES AND DATES OF DATA COLLECTION:

There are to be four main collection dates for the project. They are to span the course of a year and therefore include the range of four seasons in the data. Only two of these sampling dates will be covered in this paper as subsequent collections are to be completed after this paper has been compiled. Therefore, there is great scope in terms of further study and it is expected that trends noticed here will continue over the third and fourth sampling period. The dates for the sampling are as follows:

o Weds 6th April 2011 o Weds 13th July 2011 o Weds 9th November 2011 o Weds 29th February 2012

The design of sampling across the four seasons will aid the determination of the sources and types of pollutants affecting this river. In most cases, it is not expected to see the same pollution throughout the year. Undertaking a seasonal analysis will develop a full picture and highlight the effect of variables such as climatic variation, seasonal intensity of agriculture and application of road salts in winter.

As the sampling is dependant on help from fifty volunteers, the dates of the sampling is fixed. The logistics of rearranging a date make it unfeasible to change if for example low quantities of rainfall are observed as was the case in July. Therefore, the quality of the data for each sampling event will be investigated and discussed accordingly.

- 15 - 2.3 LABORATORY TECHNIQUES AND SAMPLE ANALYSIS:

Following each sampling „dip‟, the 50 samples were collected up at Hardwick Hall, labelled, packaged in ice and transported back to the University of Sheffield for analysis. Then, a full investigation into the water quality was undertaken in the University environmental engineering laboratory. This included:

o pH analysis: The pH analysis was undertaken using an ORION 5Star automatic pH reading system. Analysis required placing the probe in the sample jars and the sensor read the ions transferring across its filament to produce a value for pH. The equipment was calibrated with a benchmark pH 7.00 solution to ensure the readings from the probe were accurate. This pH7.00 solution was checked every 10 samples to determine if the calibration had drifted. If it deviated by more than 0.2, the equipment was recalibrated and the samples re-evaluated. The probe was rinsed with deionised water and dried prior to assessing the pH of the following sample to avoid contamination.

o Dionex analysis: Initially, two 0.5ml Dionex vials were filled with each of the 50 samples. Blanks of deionised water were included every 10th sample for quality control. These were loaded into vial racks and inserted into the Dionex machine for analysis. The Dionex equipment measures ions in the water to determine the concentration of key constituents. Analysis was continued overnight and results were fed to a networked workstation for visual output. These results were compiled into the spreadsheets in Appendix A and analysed for their variation. Blanks were checked to ensure expected results were obtained maintaining quality control of samples. Measuring two samples for each point allowed verification of results for the 50 locations.

o BOD analysis: In order to analyse the biochemical oxygen demand (BOD), each of the 50 samples were diluted 20 times with deionised water. An additional blank sample was produced as a benchmark. The diluted samples were then evaluated using a BOD specific sensor. These results were recorded and the 50 individual samples were sealed and left to incubate for a

- 16 - period of 5 days. The samples were stored at room temperature (approx 19oC) and in darkness. Upon completion of the 5 day period, the samples were removed and reassessed. In evaluating the BOD of the samples, the benchmark solution was checked every 10th sample to ensure the calibration had not deviated.

2.4 QUALITY AND CONFIDENCE IN COLLECTED AND ANALYSED DATA:

It is extremely important in an investigation like this to ensure that collected data is accurate and believable. In order to make solid conclusions and recommendations to decision making parties; the data must be a fair representation of actual field conditions. Every effort has been made to make data collection, analysis and presentation as accurate as possible. Overall there is confidence that the findings here are fair and this is attributable to the thorough protocol with respect to data quality. The methods of quality control included:

o Equipment calibration: Prior to all analysis, equipment has been calibrated as per the instructions of the instrument. These have then been verified by analysing benchmark solutions of known concentrations. Only where these readings match with the expected values has the equipment been used to measure the 50 Doe Lea samples.

o Repeats and blanks: Repeat measurements have been completed at random to ensure that readings don‟t suddenly differ during analysis. In addition is the sampling of blanks. These are controls of known concentration and these were used in particular in the Dionex analysis to ensure accuracy throughout.

o Calibration drifting checks: Where an instrument has been calibrated, it has been retested against the benchmark solution on every 10th sample. This check ensured that a fair calibration was maintained throughout the procedure.

- 17 - To ensure that the data derived in the University laboratory is a fair representation of the current river conditions, it has been compared to Environment Agency data for the same stretch of river. The results of this are displayed in the analysis section later.

2.5 HYPOTHESES AND EXPECTATIONS OF SAMPLING DATA:

With the variety of landuse in the catchment, there are many expectations for this project. There are two underlying concerns within the catchment; the water quality and flow. The additional expectations of the projects are:

o Water quality degradation is due to the application of agricultural fertilisers, mine and sewage treatment discharges in the catchment.

o The road network through the catchment, particularly the M1 will have a significant influence on the water quality

o Water quality will be noticeably degraded downstream of Bolsover

o Effects of agriculture will be more prominent over the April and July samples

o Pollutant concentrations will increase in summer due to reduced flow

2.6 REPRESENTATION OF COLLECTED DATA:

Throughout this report there has been a strong use of software package ArcMAP. Geographic Information System (GIS) programme ArcGIS was selected due to the ease of manipulation to represent an array of spatial data as developed in this investigation. ArcMAP is simply a subsidiary programme of ArcGIS.

It is a popular and widely used method of data representation in river and catchment investigations such as works of Harris et al. (2004) and Hiscock et al. (1995). Application of multiple layers of information can be personally manipulated to produce tailored outputs. Revision of maps is simple when new data needs to be analysed and plots are accurately mapped due to the universal and precise nature of its coordinate system. The ability to distribute concentrations of pollutants on a colour scale makes interpretation of outputs simple even for non-educated readers in the subject. Therefore GIS has been chosen as the best solution to represent data derived from this investigation.

- 18 -

The majority of discussion in this paper derives from visual analysis of the GIS outputs. The colour gradient system immediately highlights areas of particular concern within the catchment and comparison can determine likely sources of water quality degradation. To further investigate locations of particular concern, mass balance of river reaches can be investigated. A strong variation of plot colour between two river reaches highlights specific areas where mass-balance investigation is to be undertaken.

As the available data will only comprise of April and July‟s dips, there will not be much scope for statistical analysis of the information. There is not a significant quantity of data to perform mean and standard deviation etc for the datasets. However, it is possible to analyse the spread of concentrations across the catchment. This allows the extreme values to be determined and aids the detection of the largest pollutant problems.

2.7 ADDITIONAL FIELD DATA COLLECTION:

In order to validate much of the information in the literature and estimations of a rainfall-runoff model, it will be required to take field measurements of flow around the catchment. The effects of seasonal variability will have a significant effect on flow, so field measurements are one particular data collection requirement. For an accurate mass balance, along with the concentration of pollutant, flow must be known. To estimate the field conditions, a flow measuring day was undertaken to measure stream cross-sections and velocities to estimate flow. Field measurements were only completed for the July sampling and were used to validate model flow estimates for the catchment.

The flow was measured at eight points in the main river, tributaries and springs on July 25th 2011. These measurements and a plot of where they were taken in the catchment are included in figure 3.20 later in the paper. Using this information to validate the estimation of flow across the entire catchment underlined the importance of measuring it in the field. It therefore is highly recommended for future studies.

- 19 - 3.0 ANALYSIS OF DOE LEA RIVER SAMPLES:

It is known from past literature that the Doe Lea Catchment has many drivers of water pollution. These include agricultural (Heathwaite 1993, CIWEM 2000), mining (NRA 1994, Younger 2000, Bridgewater 2010), industrial (Skinner, 1992; Schoon, 1994), major highways (Ander et al. 2000) and other types such as sewage treatment works outfalls (Bardill, 2011). These can all contribute to poor flow conditions as discussed in some detail by Gustard et al. (1992). As explained in the methodology chapter, a full and unique sampling of the catchment was undertaken by the National Trust and the Catchment Science Centre. However, previous studies have been undertaken by the Environment Agency (EA, 2011). The data published for these studies is not as thorough as the data collected from the sampling programme undertaken for this paper; however, it acts as a good marker of quality assurance of collected data.

In this chapter, a full analysis of the collected data is undertaken. This includes the notable trends seen in the analysis, specific points of interest and a relation of each type of pollution to potential sources. A comparison of this data with current Environment Agency (EA) findings develops a level of confidence between the two analysis methods. An attempt of estimating flow in the catchment allows a greater understanding of catchment characteristics and allows a mass balance to be applied to river reaches of particular concern.

3.1 COMPARISON OF SAMPLES WITH ENVIRONMENT AGENCY RIVER MONITORING DATA:

This project is not unique in the Doe Lea. The EA maintains background monitoring of all major rivers in the UK and collects information regularly on the Doe Lea at its monitoring point at Staveley. In order to verify the robustness of the data collected in the field, some of it has been compared against recent EA data. Widely available through EA routes are nitrate and phosphate concentrations in the Doe Lea. These have been compared to the data collected in the field for the Doe Lea Dip of April. The EA also present chemical and biological quality of the river. This is measured on

- 20 - an A-F grading and so cannot be directly compared to the Doe Lea Dip results. However, what comparison can be made gives confidence in the data collection methods as shown here in figure 3.1:

Figure 3.1: Environment Agency sampled values for phosphate and nitrate (sites 1, 2 and 3) (Stars) against the samples from the Catchment Science Centre (Spots) (EA, 2011)

Dip Result 42a 35 34 Nitrate 25.64 mg/l 26.50 mg/l 29.95 mg/l Phosphate 0.64 mg/l 1.29 mg/l 1.31 mg/l EA Result C B A Nitrate 25.38 mg/l 32.25 mg/l 32.31 mg/l Phosphate 0.36 mg/l 0.86 mg/l 0.77 mg/l

Figure 3.2: Comparison of results from the April dip with the published 2009 average results from the Environment Agency for the same locations. Concentrations at A, B, C, 34, 35 and 42a are the values for the plots on figure 3.1 above.

By comparing the two analyses, there is sufficient correlation to give confidence in methods of sampling and analysis undertaken on the Doe Lea Dip project. Although there is clearly some slight deviation in results, the EA values are calculated from a long term average whereas the dip results are from the April sampling only. The values derived for nitrate are very similar with the largest deviation being a 19% change at point 35/B. The other two sites are within 10% of each other and so the dip results can be accepted as an accurate measure of river characteristics. The change is greater for phosphate, though again the EA values are derived from a long term average. It would be expected to see elevated levels of phosphate due to the

- 21 - application of fertilisers in the spring period which explains the elevation compared to EA statistics.

Over this stretch of water, the EA defines the nitrate and phosphate quality as grade 5 (1 = very low to 6 = very high). The grading system is defined as shown in figure 3.3 which will be used further in the report to aid the analysis of nitrate and phosphate concentrations within the Doe Lea watercourse:

EA Classification for PHOSPHATE Grade Boundary (mg/l) Description 1 0.02 Very Low 2 0.06 Low 3 0.1 Moderate 4 0.2 High 5 1.0 Very High 6 > 1.0 Excessively High

EA Classification for NITRATE Grade Boundary (mg/l) Description 1 5 Very Low 2 10 Low 3 20 Moderately Low 4 30 Moderate 5 40 High 6 > 40 Very High

Figure 3.3: Environment Agency classification for Phosphate and Nitrate pollution in UK rivers (EA, 2011)

3.2 AGRICULTURAL POLLUTION IN THE DOE LEA:

Agriculture is one polluter responsible for non-point source pollution to the Doe Lea. Studies such as that of Dermine and Lamberts (1987) have described just how difficult it is to „clearly isolate‟ the contributions of agricultural fertilisers (specifically nitrate) from entering the watercourse via runoff. Their investigation used a discharge to concentration relationship to identity a major input of nitrates from soil leaching. A similar investigation later in this paper is used to determine the source of agricultural pollutants from diffuse non-point sources in the catchment.

It is already known that phosphates provide a strong challenge to water quality in the Doe Lea (Bardill, 2011; EA, 2011b). There are a number of sewage treatment works along the course of the river which potentially are detrimental to water quality and cause increased loads of phosphorous in the watercourse. However, these are point- discharges and the locations of all STW are known. Septic tanks are used in the upper reaches of the catchment, though no detailed information on the effluent of these is available. Either way, perhaps most importantly in the catchment is the

- 22 - interactions between fertiliser application and concentration in the river. There are numerous pathways for diffuse pollutants such as nitrate and phosphate to reach the river. This paper investigates the nature of these interactions to determine the discharge to the river and aims to locate river reaches of particular concern to water quality. It is anticipated that concentrations will fluctuate throughout the yearly cycle of the sampling. A key driver for this is the disturbance of land by agriculture which has been found to contribute significant quantities of nitrate and phosphorous to watercourses (Neal et al., 2010). This will be most proficient in the spring and autumn where the heaviest agricultural processes are undertaken and intensive application of fertiliser takes place.

The impacts of increased quantities of nitrate and phosphate within the river can have profoundly detrimental effects on its quality. A major problem occurs due to the effects of eutrophication, encouraged in part by the increased availability of diffuse waterborne nutrients. It is well known that plant yield increases with the availability of nutrients as discussed in a study by Cooke (1982), who looks at the balance of maximum yield of plants against the environmental consequences. Additional supply of nutrients can cause uncontrolled blooming of algae and bacteria which in turn leads to a reduction in water quality. Oxygen is used up in the process making it uninhabitable for fish and ultimately reduces the ecological status of the river. The Doe Lea is an example of a river with poor ecological status (EA, 2011b) so the effects of eutrophication from agricultural runoff is a high possibility.

Phosphorous is a key driver of aquatic plant growth and eutrophication (Haygarth, 2000). Many point source polluters of phosphorous, such as sewage treatment works (STW), have gradually improved the quality of discharge into the receiving water. However, there is still a readily available supply of diffuse phosphorous from agricultural runoff. Being a non-point source pollutant, it is again harder to track; though applying a mass balance method of analysis to problematic river reaches allows effective analysis of contributions to the river.

In order to control the application of fertiliser, both in quantity and time, the Code of Good Agricultural Practice (CoGAC) was developed (Heathwaite et al. 1993). This was created in an attempt to determine a balance for fertiliser application whilst

- 23 - minimising environmental impacts. However, farming still remains responsible for ‘over 50% of the total nitrogen discharge into receiving surface waters’ (European Union, 2010). An additional problem being tackled by the CoGAC guidelines is over application of fertiliser products. A study by Sylvester-Bradley (1993) estimated that between 10%-60% of fertiliser applied to plants was not taken up and was free to runoff into receiving watercourses.

It is clear that the effects of new legislation such as the Nitrate Directive (ND) and Water Framework Directive (WFD) are having a positive influence on nutrient concentrations in the Doe Lea River. Figure 3.4 shows a plot of nitrate and phosphate concentrations within the Doe Lea River between 2006 and 2009 from EA analysis. It is clear to see that the mean value is falling and progressing towards the WFD targets for 2015.

A chart of Environment Agency data for the Doe Lea Catchment (sample points 34-35) showing reduction of Nitrates and Phosphates over the last 5 years

38 1.2 37 1 36 0.8 35 0.6

34

(mg/l) (mg/l) Nitrate Nitrate 0.4

33 Phosphate concentrations concentrations concentrations concentrations 32 0.2 31 0 2005 2006 2007 2008 2009 2010 Nitrate Year of samples Phosphate

Figure 3.4: Plot of Environment Agency data showing reduction in Nitrate and Phosphate in the River Doe Lea over the past 5 years

The EU Nitrate Directive has determined the maximum admissible concentration of nitrate as 50mg/l. The sampling results for the catchment have shown that levels are predominantly below this value. However, point 47 provides an exception as the recorded nitrate concentration is 66.69mg/l. This would therefore fail the nitrate directive standards and render it a Nitrate Vulnerable Zone (NVZ). A plot of the samples collected for the Doe Lea Dip against the EA 1-6 classification is displayed below in figure 3.5. This illustrates the quality over the whole catchment and highlights areas of particular concern for further investigation:

- 24 -

Figure 3.5: Plots of nitrate and phosphate against the Environment Agency classification as shown in figure 3.3

It is concerning that 4 sample points register a concentration of >30 mg/l rendering them „high‟ or „very high‟ for the April analysis. For phosphate, 10 points registered concentrations of >0.2 mg/l in April classing them as „high‟ to excessively high‟ in the EA standards. What is particularly noticeable is the increase in nitrate and phosphate concentrations downstream of sample point 34 for the duration of the river. This is more or less the point where the catchment switches from primarily agricultural landuse to mainly industrial and mining landuse. Therefore a particular area of interest for a mass balance analysis would be between sample points 28 and 34 to locate the input of these pollutants.

At this stage, some information came to light with regards to New Bolsover STW and discharges to the watercourse. Although there is no official information, Bardill (2011) stated that the development of two new estates at Palterton, southeast of Bolsover was known to cause overcapacity flow to Bolsover STW during heavy storms. If this is the case and overflow through CSO‟s reach the watercourse, it could potentially have the effects of increasing nitrate and phosphate concentrations as seen

- 25 - in the Doe Lea in April. Of course, there are many other potential causes, though the point-source nature of a sharp increase suggests it emanates from one point. New Bolsover STW is located directly between the two sample points and so a mass balance is likely to identify pollution sources and the concentrations added. Approaches were made to Yorkshire Water who maintain the facility, to obtain flow and quality information for discharges; though the information made available was not of particular use to solving this issue.

Evident locations of agricultural concern were sampling points 26 and 47 where the highest two values of nitrates were seen. At location 47, the nitrate value was 66.67 mg/l, which far exceeds the Nitrate Directive maximum level of 50 mg/l. Investigation of this spike was undertaken by Bardill (2011) who found a large agricultural waste tip on the adjacent bank to the river. It was presumed that this was the source of the spike in concentration which reduced to average levels when diluted at the downstream sample point. Concerns were raised to the landowner and methods to alleviate the pollution and prevent it reoccurring were established. In the July analysis, the tributary was dry and hence no sample could be established. Therefore this could not be confirmed as the only source of nitrate in this area. To have confidence in this land management decision, it is hoped that nitrate concentrations will have returned to normal levels by the November Dip. This provides an area of further study beyond this particular paper.

In addition, location 26 near Sutton Scarsdale saw the second highest concentration of nitrate, recorded at 41.42 mg/l. Personal discussion with Bardill (2011), revealed that within the close upstream vicinity of the sampling point is a pig farm at Owlcotes. It is expected washoff from eroded bare land into the receiving water is responsible for this spike in concentrations. Again, the National Trust is working with the land owner to reduce emissions into the tributary.

It is clear to see that once the sample analysis results have been obtained, investigation into areas of concern can be completed. Investigation here by the National Trust has revealed potential sources for locations of high nitrate concentrations. By implementing land management strategies progressively over the period of the investigation, it can be seen whether these are proving a success.

- 26 - Alternatively, it can also be seen whether there are other underlying contributors of pollution which need further investigation and management.

3.3 MINING INFLUENCES ON THE DOE LEA CATCHMENT:

It is known that mine drainage contributes to the water quality problems within the Doe Lea catchment. This has also been found to „result in a net import of water within the catchment’ (Marsh & Hannaford, 2008). The river is among the list of 57 watercourses highlighted by the National River Authority as being affected by discharges from abandoned mines and spoil tips (NRA, 2004). The Doe Lea Catchment is set in a heavily mined area of the UK. All collieries are long since closed and now lie redundant. However, flooding of these mine networks in many cases leads to overflow and subsequent discharges of ferruginous mine waters into the River Doe Lea. In addition is the abundance of spoil heaps constructed from mine waste which are known to leach polluted water into the Doe Lea. The chemical reactions and oxidation of pyrite within the mine generally produce polluting discharge containing a number of different heavy metals (Younger, 2001). It is the characteristic elements of this discharge that enables us to recognise potential drainage locations on the Doe Lea catchment map.

Not all mine water discharges are of poor quality (NRA, 1994). As this is a heavily mined area, it is expected that some discharges will be clear and contribute positively by diluting the more harmful mine discharges within the watercourse. These however, are less likely to be noticed as only high polluting discharges stand out on the analysis maps.

In communications with the Coal Authority, who retain responsibility for abandoned coal mines in the UK, it was stated that mine drainage does not surface in the Doe Lea Catchment. They stated that’ water levels within the abandoned mine workings are well below the surface so are not relevant to your studies’ (Coal Authority, 2011). To improve water quality in the area, mine waters are pumped to treatment ponds outside of the catchment to be naturally treated before returning to the watercourse. However, from analysis of the samples it is clear to see that contrary to the Coal Authorities claims, some drainage is reaching the Doe Lea watercourse due

- 27 - to the high concentrations of characteristic pollutants. This is especially clear at point 33 which lies adjacent to the site of one of the regions largest collieries.

To develop an idea of the influence that mining has on the Doe Lea catchment, a map of former collieries, tips and shafts has been developed in figure 3.6. This is perhaps not an exhaustive list, though does include all the major mining landuse as displayed by NRA (1995):

Figure 3.6: A plot of the mining influences in the Doe Lea Catchment and description (After NRA, 1995) [An enlarged map is included in Appendix B for reference]

From the analysed laboratory results, high levels of iron have been recorded across the catchment. The highest values and biggest concerns lie at sampling point 33 where 2.45 mg/l was discovered and sample point 12 where 1.41 mg/l was recorded. There are concerns over the poor ecological value of the catchment and this may prove to be a driver of this. Recent research by Younger (2000), found that ‘dissolved iron concentrations in excess of 0.5 mg/l can be expected to decimate invertebrate populations as iron precipitates blanket the river bed and disrupt their food supply’. It is concerning that in this study, 29 of the 50 sites recorded iron concentrations above 0.5 mg/l, with sites 33 and 12 having by far the highest. There

- 28 - is a small degree of staining of the river bed in the catchment as iron within the mine drainage oxidises and precipitates out leaving the characteristic orange deposit (NRA, 1994). This is known to be the case at sampling site 5, by visual confirmation at Silverhill Colliery though needs verifying at sites 12, 33 and 41. There is confidence that the analysis of the Doe Lea Catchment shows significant signs of numerous mine drainage points. A recent paper by Ander et al. (2000), discussed how metalliferous and coal mine discharges contain ‘high concentrations of toxic elements such as copper, zinc, lead, cadmium and arsenic’. These are also known to give ‘potentially detrimental health effects in high doses’. The analysis of the Doe Lea results (Appendix A) showed high concentrations of each of these metals as shown here in figure 3.7. This can therefore help justify that the water quality issues seen here at point 33 are related to mine discharges. Similar effects are also seen at sampling point 12 where high concentrations of copper, iron, zinc and lead were recorded.

Cadmium Cobalt Cromium Copper Iron Manganese Nickel Lead Zinc

(Cd) (Co) (Cr) (Cu) (Fe) (Mn) (Ni) (Pb) (Zn) Concentration at sample point 33 0.029 4.96 14.73 11.22 2449.89 4075.21 17.51 2.34 32.18 (g/l) Average of all 50 sampling 0.001 0.55 5.10 3.28 620.21 237.59 3.72 0.98 13.59 sites (g/l) Rank among 50 sites in 1 1 1 2 1 1 1 5 5 catchment Figure 3.7: Concentrations of heavy metals at sampling point 33 suggesting mine discharges to watercourse.

Chloride is a good indicator of mine related drainage as chlorine is abundant in English deep mined coal such as that in the catchment (Dept for Communities and Local Government, 1999). Analysis has shown high chloride readings at locations 12 and 41. Site 41 lies on a mining spoil heap so it would also be expected to succumb to mining related water quality issues. It is however interesting to note that results from point 12 in the July analysis did not suggest significant mine relation. Therefore it can be said that only site 33 is consistently at stress from mine water discharges as this continued to July. Mining database (Aditnow, 2011), returned proximities of site 12 with Pilsley Colliery and site 33 with Arkwright Colliery (Bridgewater, 2010). Both of these mines are long since closed, however, they appear to be contributing poor quality waters to the Doe Lea and Pools Brook as the analysis has shown.

- 29 - Generally, mining has been proven to be an accelerator of the chemical reactions contributing to natural ferruginous discharges. Younger (2000) states; „mining is by far the most common cause of ferruginous discharges worldwide’. Ander et al. (2000) claims oxidation of pyrite is the fundamental cause of water quality degradation in mining environments. It can lead to a noticeable increase in iron and sulphur concentrations, which has been seen here in the Doe Lea Catchment, especially at sample point 33.

Although the concentrations of this predicted mine discharge is high in relation to the remainder of the Doe Lea Catchment, it is relatively low compared to other examples discussed in literature. This may be due to a lower severity, dilution from less polluting mine waters (NRA, 1994) or may also be attributable to the largest concentrations having washed through previously. Wood et al (1999) recently researched minewater pollution and the duration of its effects. Six discharges were studied in detail and it was found that mine water discharge was most severe in the first few decades after a discharge begins (the ‘first flush’). The study concluded that ‘mine discharges settle down to a lower level of pollution (particularly in terms of iron concentration) within 40 years’. The paper also determined that it would be normal to see iron levels drop to less than 10 mg/l soon after the first flush. This also has been seen in the Doe Lea catchment as all locations considered to produce mine discharges have iron concentrations between 1 mg/l and 2.5 mg/l. This may explain that the highest potential concentrations of mine discharge have now passed and a prolonged minimal concentration will continue to flow. This is good news in terms of remediation of this discharge as lower concentrations will be easier to treat.

Noticeable trends can also be seen at points 5 and 26. These appear to have elevations of limited minerals but both produce spikes in iron, aluminium, manganese and lead. At sampling point 5, it is known that there is mine discharge emanating from Silverhill Colliery and ochreous staining (orange iron precipitate) has been reported in the river. The net environmental effect of these discharges are negative on the watercourse, however, they are of a much smaller intensity than the expected discharges at points 12 and 33.

- 30 - 3.4 INDUSTRIAL INFLUENCES:

It is important to note following the thorough dioxin studies in the 1990‟s (NRA, 1995; EA, 1998) that the April and July dip results do not appear to have been skewed by this industrial pollution incident. Much of this pollution remains embedded in the sediment of the river and it was an important stipulation that volunteers do not disturb the sediment when collecting water samples. This appears to have been followed and a fair spread of current water quality has been presented.

The most noticeable industrial pollution has been seen at sampling point 15 where the highest value for zinc was recorded from the 50 samples; at least 3 times the concentration of the second highest. This coincided with highest levels of cadmium, nickel and barium.

Located upstream of sample point 15 is Holmewood Industrial Estate. It has been an area of concern, to which the sample results provided unarguable evidence. Located in the estate is a major manufacturer of nickel and zinc plating. This would explain the elevated concentrations of these metals in the river at points 15 and 16. High concentrations of cadmium are most likely attributable to the zinc-cadmium and nickel-cadmium relationships in the plating industry (Ayres and Simonis, 1994). It is not the aim of the project to point the blame for river quality degradation; however it would make sense that this is the direct cause of the metal pollution at sites 15 and 16 of the Doe Lea Dip.

3.5 URBAN INFLUENCES:

It has been recently suggested by Neal et al., (2010) that there is a strong link between population densities and dissolved phosphorous concentrations in rivers. It was seen in the April analysis that phosphorous concentrations spike at sample point 34. This is 150m downstream of New Bolsover STW and is most likely to explain the elevated concentration of nitrogen and phosphorous within the lower urbanised reaches of the Doe Lea.

- 31 - Although the phosphorous values appear high from sample point 34 on the River Doe Lea to its confluence with the River Rother; they do not breach the statutory levels for STW release under the Urban Waste Water Treatment Directive (UWWTD). The directive defines a maximum output of 2 mg/l for population equivalent of 10,000-100,000 (European Commission, 1999). However, a value of 2 mg/l outfall from the STW would render the concentration „excessively high‟ in the river under the EA classification for phosphorous (EA, 2011). Regardless of this, there is a 1.0 mg/l elevation in concentration of phosphorous in April and a 4.85 mg/l rise in July; which is most likely to derive from the STW. The rise of 4.85 mg/l observed in July is extremely excessive and is potentially very harmful.

For nitrate, the concentrations recorded breach the UWWTD statutory levels of max 15 mg/l; however there is a trend upstream of sample point 34 which is producing elevated background levels prior to New Bolsover STW outfall. Nevertheless, an increase of 19 mg/l nitrate concentration between sample point 28 and 34, where the STW outfall lies suggests that the water quality discharged from the works is failing UWWTD statutory levels.

In addition, Neal et al., (2010) discuss how their findings show phosphorous levels within the river change remarkably during high and low flow conditions. They state that during the low flow conditions, as seen in the Doe Lea in July, there is a high biological uptake driven by the low velocity and subsequent increased water residence time. In addition, they also suggest how storm flows flush the septic tanks, STW‟s and stored phosphorous in the unsaturated zone and result in a noticeable rise in phosphorous concentrations with the river (Neal et al., 2005). This may prove the case for the large rise in July, however the point nature of the rise between 28 and 34 may suggest otherwise.

In addition to nitrate, other important forms of inorganic nitrogen are ammonium and nitrite. Ammonium gives perhaps the greatest concerns with regard to water quality as it can be toxic to ecology in high concentrations. Ammonium usually derives from untreated sewage and therefore may be discharged from Long Duckmanton STW which lies 100m upstream of sampling point 33 where high ammonium concentrations were recorded.

- 32 -

What is particularly interesting here is the relationship between ammonium, nitrate and the dissolved oxygen concentrations within the river. As the sampling was undertaken at defined points, it is not possible to directly establish at which point the concentrations change. To this extent, further investigation may be useful at closer intervals to get a breakdown of the transformations within the river. This would also confirm if the STW was responsible for the increase in ammonium concentration.

At location 29, the concentration of nitrate is moderate, yet at location 33 it is minimal. This coincides with a high BOD5 at this point suggesting a depletion of oxygen in the water and anaerobic conditions. Bacteria in the water use oxygen in the most readily available form; that being dissolved elemental oxygen (Manahan, 2000). Upon depletion of oxygen, the next available form is the reduction of nitrate - (NO3 ) which acts as an electron acceptor, ultimately reducing it to atmospheric nitrogen (N2) via the process of denitrification (Burt et al., 1993). Ammonium indirectly contributes to BOD in water and thus aids the depletion of dissolved oxygen.

What appears to be a discharge of ammonium from the STW suggests that the treatment process is not sufficiently nitrifying the wastewater prior to discharge. However, there is potentially another cause for the water quality degradation seen here. Adjacent to the STW lays the remains of Arkwright Colliery. It is evident that some mine drainage is surfacing here as there are particularly high concentrations of mine related pollutants. These include cadmium, cobalt, chromium, copper, iron, manganese, nickel, lead and zinc. Should the mine drainage be the cause of the degradation, the ammonium may derive from dissimilatory nitrate reduction to ammonium (DNRA). However, Whendee (2001) states this is relatively uncommon in natural environments.

Further downstream at location 38, 39 and 42, the concentration of ammonium is reduced in a similar proportion to an increase in nitrate. This would immediately suggest that the effects of nitrification were being seen. Manahan (2000) states that nitrification is particularly important as ‘transformation to nitrate enables maximum assimilation of nitrogen by plants’. Nitrification is possible in the presence of high

- 33 - quantities of dissolved oxygen. Analysing a plot of BOD5 shows that downstream of point 33, the DO returns to normal concentrations and would encourage the oxidation + - - of ammonium (NH4 ) to nitrite (NO2 ) and subsequently nitrite (NO2 ) to nitrate - (NO3 ).

This would explain the reduction of ammonium and increase in nitrate as shown in figure 3.8, as ammonium is transformed to nitrate via the natural processes of the nitrogen cycle. The levelling of the graph at 38 and 39 may be explained by a land drain tributary which drains colliery wasteland and may inject a new concentration of ammonium. At point 42, nearly 3km downstream, the nitrate and ammonium levels have returned back to average levels seen across the remainder of the catchment.

A graph of changes in nitrate and ammonium concentrations in Pools Brook 25 25

20 20 29 33 38 39 42 15 15

10 10

5 5

Concentration in mg/l in Concentration mg/l in Concentration

0 0 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 Distance along river from source (m) Nitrate (mg/l) Ammonium (mg/l) Figure 3.8: A graph showing the effects of expected nitrification as ammonium transforms into nitrate in Pools Brook after an influx of ammonium presumed to be from Long Duckmanton STW.

This will be further analysed when looking into mass balance of river reaches later in the paper to attempt to distinguish the source of the pollution as either the STW or mine drainage.

3.6 FURTHER ANALYSIS OF THE CATCHMENT, FLOW ESTIMATION AND MASS-BALANCE OF RIVER REACHES:

More detailed analyses can be undertaken by looking at the mass balance of each river reach. To accurately investigate this, a number of parameters need to be determined. The sampling locations and the concentration of pollutants have already been established. Though to analyse the transformations between river reaches, a sensible estimation of flow must be established.

- 34 -

In order to assess the flow within the river, a rainfall runoff model has been attempted to define a value of flow for each of the 50 sampling locations. The EA currently holds detailed records of flow which have been measured at their gauging station located near Staveley adjacent to sampling point 42. The mean river flow through this point of 0.572m3s-1 (Marsh & Hannaford, 2008) will act as a benchmark in estimating the flow over the course of the river. This benchmark value was compared to field measurement of flow in various locations along the Doe Lea River and its tributaries. In total, eight flows were measured at different locations in the catchment. The locations of these measurements and how this relates to the EA values is discussed later in the report. However, field measurements returned greatly reduced flows compared to the annual average due to the prolonged dry period.

There are many variables affecting the quantity of precipitation that reaches the watercourse. Of course, not all the precipitation to reach land will runoff directly to the river and it tributaries. Similarly, not all of the flow in the river will be attributable to precipitation. There are known discharges from abandoned mines and STW outfalls for example. However, there are many more unknown points of discharge to the river from industry, urban overflows and agricultural land drains etc. It is not feasible to map all of these inputs. This is mainly due to no single party being able to confirm exactly what is discharging into the river and in what quantity.

Therefore to estimate the flow along the course of the river, it is important to look at the following factors:

o Precipitation over the catchment for the period of sampling

o Land use (urban areas to cause greater runoff and green areas encourage infiltration)

o Soil Types (the porosity of soils and quantity of infiltration)

o Geology (behaviour of groundwater storage and movement)

o Conceptual interactions between infiltration and runoff and how these contribute/remove flow from the river

o Effects of artificial contributions and abstractions

- 35 - This can be crudely represented by a simple water balance/rainfall-runoff model which shows the transport pathways of the diffuse pollutants in the catchment:

Accumulation of debris and Application of fertiliser and dirt and deposition of waste pesticides

Precipitation Dilution

Surface water drainage Runoff Diffuse pollution on soil surface

Infiltration

Throughflow Diffuse pollution in subsurface layer

Sewage Treatment outfall Leaching

Industrial outfall River Groundwater

Mine drainage Direct discharge

Figure 3.9: A Conceptual interaction of pathways of pollutants to the river in the Doe Lea Catchment

3.7 DEFINING CATCHMENT PRECIPITATION:

As the river flow data available from the EA is calculated from a 40 year average, the expected precipitation over the catchment should also be estimated from data over a similar period. As specific flow data for the time of the fieldwork is not available, it must be estimated from what is available. The unseasonably dry conditions in the catchment in 2011 make this difficult to estimate and confidence in estimates is therefore reduced. For the April analysis, the flow has been estimated using a rainfall runoff model from rainfall data over the catchment for March to June 2011 (figure 3.10). To increase accuracy for the July analysis, field readings of flow data were measured and compared with an actual rainfall for that period. At the time of measuring the flow, it had not rained heavily for over a week and so the majority of flow would be attributable to groundwater and delayed runoff. As hand measured flows for July were more accurate, the flow for April was back calculated from this estimate.

- 36 -

An estimation of total precipitation for the catchment has been established at 714mm annually; or 1.96mm/day (CEH 2011, MET Office 2011). It would be expected to see greater flows in winter than summer and so this is why amendments were made to the July sampling by measuring actual flow for the catchment at that particular point in time. The July flow would be predominantly supplied by stored groundwater and storm rainfall. Average precipitation for the April period has been estimated from MET Office (2011) data from the region and therefore provides a sensible estimate for precipitation over the catchment. Hence:

Month Mar 2011 Apr 2011 May 2011 June 2011 Average Rainfall 19.7mm 11.5mm 24.7mm 42.0mm 0.62mm/d

Figure 3.10: Rainfall over the Doe Lea catchment. [Values from publically available datasets produced by the MET Office (2011)]

3.8 LAND USE IN THE DOE LEA CATCHMENT:

The Centre for Ecology and Hydrology (CEH) and the Natural Environment Research Council (NERC) have gathered a substantial database on river catchments within the UK. There is a sampling location on the Doe Lea near its confluence with the Rother at Staveley. This provides a wealth of information of the catchment from flows to soil types. Also established is the landuse within the catchment. CEH (2011) have determined the landuse to be populated as below with a plot of landuse in figure 3.11 over the page:

o Woodland: 5%

o Arable/Horticultural: 44%

o Grassland: 28%

o Urban Extent: 20%

o Other 3%

- 37 -

Figure 3.11: Maps of the land use in the Doe Lea catchment (using data from CSC, 2009)

- 38 - Land uses will have a significant effect on the flow in the river. It determines the time between rainfall landing on the catchment surface and it reaching the water course. For example, in urban areas, runoff will produce a spike on a hydrograph due to the unrestricted nature of flow. However, in rural areas, the discharge to river is more controlled and the hydrograph would show a more gradual slope to due the retention of water in soils and blocking by vegetation. Therefore to complicate things further, not only is the quantity of runoff different with land uses, the time at which it reaches the watercourse is affected also.

Research by Shrestha, 2004, suggested a crude estimate for a percentage distribution of precipitation to runoff, infiltration and evapotranspiration for a range of land uses. Accurately defining the quantity of runoff from precipitation is difficult and requires extensive monitoring of the land. However, from this research, an estimate has been made which can be interpreted for the land use in the Doe Lea catchment to establish river contributions and flow in the river. This distribution was estimated as follows:

(1) (2) (3) (4) Natural Ground 10-20% 35-60% Fully Urban Cover Impervious Impervious Ground Cover Ground Cover Ground Cover

Runoff 10% 15% 25% 40% Infiltration 50% 42% 35% 20% Evapotranspiration 40% 43% 40% 40%

Figure 3.12: Distribution estimate of precipitation for a range of land uses (from Shrestha, 2004).

The estimations used by Shrestha (2004) provide a good starting point to estimate the contributions to river flow in the Doe Lea. This information then needs to be compared to soil types and the geology of the catchment to determine if infiltration occurs to the rates predicted.

Other studies have looked at land use and runoff contributions in the UK. Crooks et al (2006) looked at flood drivers as a result of runoff in the upper Thames catchment. It relates to the Doe Lea catchment as the land is 80% rural, though a switch from arable to grass and woodland landuse has alleviated runoff contributions to the

- 39 - watercourse. The Doe Lea is predominantly populated with arable and horticultural landuses. Should runoff contributions be too great, especially in the off season after harvesting of crops, then similar land management practices as shown by Crooks could be an option for controlling excess flows in the rivers of the catchment.

A similar recent study by Williams (2004) investigated runoff contributions as a result of landuse in the River Camel in Cornwall. The paper concluded that as a result of increased arable landuses in the catchment over a 36 year period, there was a „significant‟ increase in the annual maximum daily river flow attributable to increased runoff contributions. Intensive grazing in the Camel catchment was found to ‘exert considerable influence on soil hydrology and catchment runoff’ (Williams et al. 2004). Therefore a significant amount of understanding of runoff and river flow contributions can be determined from land uses alone. The estimated arable landuse of the Doe Lea catchment is ~50% and given the increased risk of runoff from these sources (Crooks et al., 2006; Williams et al., 2004), excess contributions of flow and diffuse agricultural pollutants can be expected. To understand the quantities infiltrating into the soil and groundwater, the soil types of the catchment have been considered also:

3.9 SOIL TYPES WITHIN THE CATCHMENT:

The catchment has a range of soils of different permeability and nature. Using data from the National Soil Research Institute (NSRI, 2011), a GIS plot of soil types in the catchment has been developed. There are two images to depict the soil conditions in the catchment. The first shows the spatial distribution and soil types and the second shows the Hydrology of Soil Types (HOST):

- 40 - Bardsey: ‘Slowly permeable seasonally waterlogged loamy over clayey and fine silty soils over soft rock’

Neutral Restored Opencast: ‘Restored opencast coal workings. Slowly permeable seasonally waterlogged compacted fine loamy and clayey disturbed soils. Often stony with thin topsoils’

Dale: ‘Slowly permeable seasonally waterlogged clayey, fine loamy over clayey and fine silty soils on soft rock often stoneless’

Aberford: ‘Shallow, locally brashy well drained calcareous fine loamy soils over limestone’

Rivington: ‘Well drained coarse loamy soils over sandstone’

Conway: ‘Deep stoneless fine silty and clayey soils variably affected by groundwater’

All information as described by the National Soil Research Institute (NSRI, 2011)

Figure 3.13: Plot of the soil types within the catchment as described by the National Soil Research Institute (after NSRI, 2011).

It is clear from figure 3.13 that the majority of the soils in the catchment are „slowly draining‟ and allow infiltration. The „seasonally waterlogged‟ nature suggests that runoff may be increased in the winter months due to reduced quantities of infiltration into the groundwater.

Next, the Hydrology of Soil Types (HOST) is a classification of soil to establish a range of their hydrological properties (Boorman et al., 1995). These hydrological properties of soils provide key information for the further determination of runoff and infiltration estimations which are required for this paper. A plot of the HOST classifications for the catchment is shown below in figure 3.14:

- 41 - HOST class 24: ‘Slowly permeable, seasonally waterlogged soils over slowly permeable substrates with negligible storage capacity’

HOST class 4: ‘Free draining permeable soils on hard but fissured rocks with high permeability but low to moderate storage capacity’

HOST class 2: ‘Free draining permeable soils on 'brashy' or dolomitic limestone substrates with high permeability and moderate storage capacity’

HOST class 9: ‘Soils seasonally waterlogged by fluctuating groundwater and with relatively slow lateral saturated conductivity’

All information as described by the National Soil Research Institute (NSRI, 2011)

Figure 3.14: Plot of the HOST soil types within the catchment as described by the National Soil Research Institute (after NSRI, 2011).

The majority of the catchment is defined as HOST class 24. It is described as a slowly permeable substrate and can provide infiltration to groundwater from surface water sources. The HOST manual produced by Boorman et al. (1995) details that „slowly permeable‟ soils have a vertical hydraulic conductivity of between 0.1 and 10 cm/day. The „freely draining‟ HOST classes 2 and 4 are described as having vertical hydraulic conductivities of >10cm/day. Hence over the catchment area and with the mean rainfall of 1.96mm/day that precipitates onto the catchment (CEH, 2011), it can be said with confidence that there is sufficient capacity for the majority of rainfall to infiltrate into the soils of the Doe Lea catchment.

This is especially applicable for HOST classes 2 & 4 (purple and blue areas in figure 3.14). NSRI (2011) data suggests that the flow through the soil is in a predominantly vertical direction and is therefore likely to directly contribute to aquifer recharge. The yellow area of the catchment, assigned as HOST class 24, offers reduced

- 42 - infiltration and greater horizontal transport and throughflow of the soil layer (NSRI, 2011). This may provide a preferential pathway for runoff rather than infiltration to the aquifer. A preliminary study of the Doe Lea by the Catchment Science Centre

(2009) suggests that this is most likely in the steep sloped areas which predominantly occur in the East of the catchment. Soil research by Chesterfield Borough Council (2009) suggests there is „substantial areas of disturbed soil where there are restored opencast works and slagheaps‟. It is questioned, though not concluded, that these areas have an effect on the infiltration potential from surface water to groundwater.

With the majority of the catchment being defined as „slowly permeable‟, there is likely to be a greater runoff occurrence during the winter months when the soil is likely to reach its saturation point. This may lead to a noticeable change in water quality over the wetter months from November to March. As the data analysed in this paper only covers the March to July period, it is impossible to prove. However, with the project to continue over the course of the winter months, this seasonal variability on the runoff quantity would prove an interesting area of further study.

Finally, with relation to soil types, there is a layer of superficial river alluvium deposits beneath the Doe Lea River. This is described by NSRI (2011) as having „slow lateral conductivity‟ whilst allowing free vertical interaction between the river and groundwater through the porous layer.

- 43 -

3.10 DESCRIPTION OF CATCHMENT GEOLOGY:

Permian Lower Coal Measures: Comprised of several „significant sandstone horizons’ namely Crawshaw sandstone which penetrates to depths of up to 55m. Sandstones dominate with the presence of minor confined aquifers

Pennine Middle Coal Measures: 1-6km wide sequence of mudstone, siltstone, sands, clays and dolomitic limestone. Sandstones are fine grained, well cemented and dense results in very little permeability and acts as an aquitard. Groundwater flow is restricted to fractures between aquitard layers. Hydraulic pathways have been constructed from the mining legacy.

Cadeby Formation: Dolomitic limestone aquifer discharging to tributaries on east of catchment. Water table slopes and drains to the east. Approx 15m thick at Bolsover with 12-18% porosity.

All information as described by the British Geological Survey (Cheney, 2007)

Figure 3.15: The geological features of the Doe Lea Catchment usin g data from the British Geological Survey via EDINA, 2011b. Geological Map Data BGS © NERC 2011

The Pennine Lower and Middle Coal Measures are constructed of mudstone, siltstone, sands, clays and dolomitic sandstones and primarily act as an aquitard due to their well cemented, dense nature. (Cheney, 2007). The legacy of coal mining in the catchment has reportedly produced preferential hydraulic pathways between minor aquifer layers that were previously isolated. The lack of groundwater storage would suggest infiltration would store in the adjacent Cadeby Formation or return to the river via the highly permeable alluvium deposits beneath the river. No aquifer data is available for the Pennine Middle Coal Measures in the Chesterfield area.

The Cadeby Formation lying to the east of the catchment consists of largely dolomitic limestone ranging from 12m–46m in depth. Its nature varies between a sandy and well cemented limestone with 12-18% porosity allowing groundwater storage and flow mainly in fractures (Cheney, 2007). The character of the Cadeby

- 44 - Formation is a gentle slope to the East, which is thought to have a draining effect on the infiltration occurring within the catchment boundary. This is also clearly visible on a local geological desk map such as that of IGS (1981). Cheney (2007), reports that the water table in the Cadeby Formation reaches a maximum in the west (shown by the green on figure 3.15) and ‘declines at a gradient of about 1 in 75 to the east’. He continues to state that ‘spring issues are common in the Bolsover area and maintain westward flowing tributaries in the Doe Lea’. The quantity of groundwater contributions can vary however as the fluctuations in the groundwater hydrograph illustrated by Cheney (2007) show changes of up to 8m in the groundwater table elevation. Thus producing changeable quantities of flow to the western tributaries and drawing more groundwater in an easterly direction away from the catchment.

3.11 SUMMARY OF ARTIFICIAL CONTRIBUTIONS AND ABSTRACTIONS:

Although there are potentially an endless number of unknown discharges to the Doe Lea and its tributaries, there are many that are documented and known of locally. Studying published material such as Ordnance Survey maps (EDINA, 2011a), British Geological Survey maps (IGS, 1981), mining databases (Aditnow, 2011) and holding discussions with the National Trust have allowed the known discharges to be plotted on a simplified map of the catchment as shown below in figure 3.16.

This will aid the analysis by method of mass balance as interesting river reaches can be immediately reviewed for the type and quantity of additional discharges. For most of the contributors described here, there is not an actual value for quantity of flow or list of pollutants added to the river. For some, such as road and industrial drainage, it is very difficult to quantify as discharges are of an intermittent nature. In the case of mine drainage, it depends heavily on the groundwater conditions and for field drains on the quantity of runoff collected. The largest and perhaps most important contributor are the STW‟s. However, information on these was not forthcoming from regulator Yorkshire Water and so estimations have had to be established for quantities of discharges based on populations served.

- 45 - Staveley STW Outfall 50 0.03185m3/s

Land drain (1.5km) Erin opencast mine drainage Unmeasured Tributary 40 44 39 42 Staveley Industrial Estate Discharges

37

49 46 46.5

38 42.5 Land drainage from disused colliery (1.5km) Land drain (1.5km) 45 Disused tip drainage 47 33

Opencast land drainage Land drainage from disused colliery 41 (1.5km) 48 Clowne STW Outfall 32 Spoil Heap Discharges 3 3 Long Duckmanton STW Outfall 0.00543m /s 0.00195m /s 36

Duckmanton Colliery Discharge Markham Colliery Mine Discharge 29 3 35 Buttermilk Lane STW 0.00130m /s Outfall 31 Unknown STW Outfall

Bolsover Colliery Mine Discharge 34 Road Drain Aztec Oils Intermittent Discharges

New Bolsover STW Outfall (Overflow in Storm) 3 28 0.01447m /s 26 27 Unidentified Tributary

22 19 18 24 A617 Road Drain 25

Stockley STW Outfall LEGEND: 23 Land drain (1.35km) 0.00217m3/s Sewage Treatment Mine Drainage 20

Urban Discharges 17.5 Land Drains Minor Septic Tank Discharges Natural Wetlands 17 Road Drains

15 16 14 Holmewood Industrial Estate Discharges 13 Pigfarm slurry entering in storm

Astwith STW Outfall 12 11 3 9 10 8 0.00091m /s M1 Motorway drain

6

7 Naturally Treating Wet Woodland

5

Unidentified Tributary 1.4km Silverdale Colliery Mine Discharge

3 Figure 3.16: Plot of known discharges to the Doe Lea populated with contributions from the National Trust (Bardill, 2011), Aditnow (2011) and Digimap (EDINA, 2011a) ©Crown Copyright/database right 2011.

- 46 - Several sources (Chesterfield Borough Council, 2009; Marsh & Hannaford, 2008) state that the system within the catchment ‘is affected by mine drainage, with a net import of water’. To accurately estimate the quantity of mine drainage contribution is not possible as the discharge details are not known in any detail other than location. They can however be plotted on a map of the catchment so the influence of the outfall on water quality can be analysed by the method of mass-balance. This can also be done for all other known potential polluters in the catchment including agriculture, industry and urbanised areas. A plot of potentially polluting land users is included in appendix D for reference.

3.12 CONCEPTUAL INTERACTIONS OF RIVER AND GROUNDWATER

There is published data on the flow of the river in its lower reaches (CEH, 2011) and included in this is the Base Flow Index (BFI) that provides a good starting point to estimating groundwater contributions to the river. Conceptually, there will be interactions between the groundwater and river due to the porous nature of the geological alluvium features (Cheney, 2007). Baseflow is the underlying trend on hydrographs and represents the quantity of flow that is provided on a continuous basis from groundwater sources (Chapra, 1997). This provides the maintenance of stream flow during dry periods where contributions from precipitation is at a minimum (Kiely, 1997). The BFI is defined as a measure of „the long-term ratio of baseflow to total stream flow’ which represents ‘the slow or delayed contribution to river flow influenced by catchment geology’ as a percentage of total flow (Bloomfield et al. 2009). Base Flow Index is particularly useful in assessing ungauged catchments and allows a realistic estimate of groundwater contributions to be derived. The averaged BFI for the Doe Lea catchment from long term trends is 0.53 CEH (2011), suggesting half of the river flow is attributable to groundwater sources.

- 47 - 3.13 ESTIMATIONS OF FLOW:

In order to estimate flow across the catchment, the area has been broken up into 50 sub-catchments which allows individual flow contribution to be estimated along with accumulation of flow along the river. For reference this breakdown is included in appendix D. We already know there is a net import of water from mine drainage and that the greatest contributor is STW outfalls. However, quantities of these are not known and therefore must be estimated. Attempts to retrieve the information from sewerage services provider Yorkshire Water were unsuccessful as they were „not able to provide me with such information‟. For the July analysis, the field flow measurements provided a base for estimating the flow across the catchment. Taking into account all that has been researched so far including precipitation, land use, soil types and geology; an estimate of flow has been established. Hence, a plot of flow for April and July has been developed:

3.14 FLOW ESTIMATIONS FOR APRIL ANALYSIS:

The April sampling period was exceptionally dry with <30% of the long term average rainfall recorded (EA, 2011e; Met Office, 2011). Flow in the river Don as recorded by the Environment Agency (2011e) was described as ‘exceptionally low’ and was just 34% of the long term average for April. This is a noticeable reduction compared to March 2011 where 47% of the long term average flow was recorded in the Don. Groundwater levels were recorded as ‘normal’ suggesting an unaffected base flow contribution and mine discharge.

An estimation from the average flow plot of CEH (2011) suggests average April flow to be approximately 0.700m3/s. Approximating 34% of this suggests flow should be 0.238m3/s at the EA monitoring point in Staveley. The estimation of the April flow model suggests the flow is 0.218m3/s and so is within 10% of the anticipated value. Again this is rough calculation as no field measurements were taken for April. A plot of April flow is included in figure 3.17 on the following page:

- 48 - Flow presented in m3/s

Figure 3.17: Estimation of flow in m3/s in the catchment for the April analysis.

3.15 FLOW ESTIMATIONS FOR THE JULY ANALYSIS:

The river flow was estimated by fitting a model to the field measurements taken on July 25th 2011. This was at a very dry time where heavy rainfall had not occurred over the catchment for approximately 10 days. In June, the region received the lowest quantity of rainfall in the country at 50-69% of normal levels compared to the long term average (EA, 2011f). As a result, the flow was uncharacteristically low. Due to the lack of rainfall and runoff, it is expected that the flow values measured were primarily the result of groundwater supply along with some artificial discharges. The Environment Agency (2011f) again declared the flow at monitoring sites along the river Don, Rother and Doe Lea as ‘exceptionally low of the time of year’. Flow in the Don was 43% of the recorded long term average for June; down

- 49 - from 51% in May. Groundwater levels however were again stated to be ‘normal’ suggesting an uninterrupted supply of river flow from the groundwater issues in the East of the catchment. The recorded soil moisture deficit in the catchment would also act to reduce quantities of runoff entering the watercourse.

In order to measure the flow, numerous locations were pre-selected to develop a picture of the flow around the catchment. During the field work it became evident that many locations selected in the upper catchment were inaccessible due to overgrowth and dry river channels. As a result, a full picture of the catchment was not measured as hoped. Nevertheless, the flow measurements taken allow an estimation of flow to be derived. This was done using a basic rainfall runoff model and fitted to the observed field values exceptionally well.

The method of measuring the flow allowed as accurate an estimation to be established as possible. To do this, the river was broken up into sections where the dimensions and velocity of flow were measured. Flow could then be calculated by multiplying the velocity by the cross sectional area and summing the resultant flows as illustrated in figure 3.18. Where possible, velocities were measured at 0.6 of the depth to provide the fairest estimate.

- 50 -

Figure 3.18: Cross-section of the river measured at Netherthorpe after the amalgamation of the Doe Lea, Pools Brook and Hawke Brook. The velocity of flow is shown in blue text and the depth of the river is shown in black text. The river was measured at a bridge, hence the channelised nature of the river sides. It also formed eddy’s in the river hence the negative flow in left of the river.

The example measured flow, which was taken in the lower reach of the catchment adjacent to the EA monitoring station at Staveley, recorded a flow value of approximately 15% of the mean annual recorded flow in the river. Simultaneously, the EA published data on their website recording the depth of flow at the monitoring station to be 0.090m (EA, 2011d). This level was beneath the ‘typical river level range of 0.100m-1.430m’ and hence highlighted the especially low flows measured in the catchment.

The annual mean daily recorded flow at the monitoring point is 0.572m3/s. The measured flow adjacent to this point on July 25th was 0.0677m3/s. Although this appears exceptional, NRA (1995) suggest that the lowest daily mean recorded flow is 0.052m3/s as recorded between 1970 and 1995. Also taking into account the EA (2011f) statement that river flow is exceptionally low at 43% of expected flow in the Don acts to give confidence to this field estimate. Therefore, the field estimates measured may accurately represent the river flow which is reduced due to the exceptionally dry conditions of 2011. A plot of July flow is shown below in figure 3.19:

- 51 - Flow presented in m3/s

Figure 3.19: Estimation of flow in m3/s in the catchment for the July analysis.

To develop this plot, an excel spreadsheet was designed for a basic rainfall runoff model. A contribution to the river was established using the average catchment precipitation (figure 3.10), the estimated fate of precipitation with land use (figure 3.11), the permeability of soils (figure 3.14) and the artificial discharges (figure 3.16). A value for rainfall contribution to the river multiplied by catchment area produced a flow value for each sample point. As STW discharges were not available, they were estimated using the population served and an average individual contribution of 125litres per person per day. Other discharges were not known and so not added. A deficit of 0.001m3/s was seen at location 33 and was added to the model. It is anticipated this is either an underestimation of the STW or potential mine drainage here.

- 52 - To compare the relationship of the model to the measured site flows, a comparison was developed as shown in figure 3.20. This shows that estimates are always within 10% of the measured values for the lower catchment, though predictions of the upper catchment cannot be verified due to no measurements being taken here. The regression between the estimates and measured values was R2 = 0.9956.

Figure 3.20: Comparison of measured flows on site to estimated flows from the prediction model. Full information of the flow measuring points including their coordinates is included in Appendix D.

3.16 ANALYSIS BY METHOD OF MASS BALANCE:

Now that there is confidence in the concentration of pollutants from lab analysis and flow from field measurement and modelling, a mass balance of river reaches can finally be undertaken. There are numerous key areas that would benefit from this type of analysis and would aid the determination of the sources and quantities of pollutants entering the watercourse.

A mass balance analysis is essentially accounting for material within a system and is widely used within environmental engineering analyses. It works on the basis of the conservation of mass law that material cannot spontaneously appear within or disappear from a system. In a river analysis such as this, it helps to identify sources of river discharges. Uncharacteristic rise in pollutant levels indicate additional flow discharging to the river and help to identify the types and quantity of pollutant emanating from that source. Most importantly it helps to derive non-point sources such as areas of agricultural runoff stress and can establish areas where better land management can be encouraged. In addition, mass balances can determine the chemical transformations occurring within the watercourse, such as those of the

- 53 - nitrogen cycle. By continuing the laws of conservation, creation of one compound e.g. nitrate will lead to mass reduction in another e.g. ammonium and so on.

Mass balances in river systems such as this are referred to as dynamic analyses due to the change of flow over time. As there is the potential for transformations to occur within the river under chemical, biological or physical drivers, the analysis deals with non-conservative pollutants. However, to best establish points of discharge to the river, conservative pollutants are analysed. These are compounds that are stable and do not spontaneously react or breakdown such as sulphate and chloride which are stable in water.

As the contributions from groundwater are not well defined, completing a mass balance should aid its understanding. For example, if chemistry within the water remains the same in relation to flow, then additions are likely to come from groundwater. However, if flow increases and chemistry changes, it is likely that inputs derive from other discharge points.

Mass balances are usually considered on mass fluxes which is the rate at which a mass enters or leaves a water system. The mass flux can be determined by:

Concentration (mg/l) x Flow (l/s) = Mass Flux (mg/s) [mass per unit time]

The mass balance is determined by analysing the change in mass flux at each end of the control volume, which in this case is each river reach:

Mass Flux Out = Mass Flux In + Accumulation + Net Chemical Production

There are numerous areas of particular interest in this investigation and these relate to the issues discussed earlier in this chapter. After an analysis of the main Doe Lea River along with Pools Brook and Hawke Brook, longitudinal plots have been developed to show the profile of mass accumulation over the course of the river. These are included in Appendix A for reference. After considering the whole catchment, attention has been focussed on the most vulnerable areas. Over much of

- 54 - the catchment, the chemistry of the river increases at a similar rate to the increase in flow. Thus suggesting that groundwater is recharging the river and is not of particular concern. However, where changes are seen between fluxes that differ from the changes in flow, or show uncharacteristic changes such as spikes; further investigation is required to determine the sources, chemistry and water quality effects of the change. Reaches where this is particularly evident include points 3-6, 6/8-11, 15-16, 28-34, 34-42a, 32-39 and 49-45 and as a result are further investigated below:

Initially, as already discussed at sample point 34 near Bolsover, a jump in phosphate and nitrate has been observed from the upstream point at 28. The mass flux out at point 34 is much higher than the mass flux in at 28 and increases at a far greater rate compared to the flow accumulation. Therefore it is fair to say there is a net accumulation of these nutrients. Chemical transformation is unlikely as there is not reduction of the components required to produce these nutrients. Instead it is expected that this mass increase is a result of STW discharge or agricultural and urban runoff from the steep sloped east of the catchment between Palterton and Bolsover:

Figure 3.21: Graph of mass balance between locations 28 and 34 to show influx of nutrients for APRIL analysis.

- 55 - Month of analysis Sample point 28 Sample point 34 Increase between points 763mg/s 2883mg/s 2120mg/s April (nitrate) 11mg/l 30mg/l 19mg/l 277mg/s 1567 mg/s 1290mg/s July (nitrate) 17mg/l 47mg/l 30mg/l

Month of analysis Sample point 28 Sample point 34 Increase between points 20.9mg/s 125.7mg/s 104mg/s April (phosphate) 0.3mg/l 1.3mg/l 1.0mg/l 5.0mg/s 173.5mg/s 168.5mg/s July (phosphate) 0.3mg/l 5.2mg/l 4.85mg/l

Figure 3.22: Table shows the increase in concentration (mg/l) and mass flux (mg/s) between points 28 and 34.

As the sudden influx of nitrate and phosphate remains in July, it is clear that this is a continuous problem and one which is having a profound effect on nutrient levels in the river. Perhaps a key indicator of the source is that of Bardill (2011a) who states the ‘sewage treatment plants at Bolsover and Stockley are working to over capacity’. These are ‘prone to overflowing and leave raw sewage on agricultural land’. This would provide an explanation to the increase and maybe justify why the mass discharged to the river is greater in the summer months when flow and runoff is lower.

The increase in concentration from this pollution causes a significant rise in the EA classification for nutrients in the river (EA, 2011a). Nitrate concentrations increase from low to moderate for April and low to excessively high in July. Phosphate concentrations increase from low to excessively high for both the April and July sampling. However, in July, phosphate levels reach five times the recommended maximum of the EA of 1mg/l. Therefore the discharge of nutrient to the river in this reach is very significant and has a severe influence of the rivers quality.

The next area of concern is at site 33 in the Pools Brook tributary of the Doe Lea. The laboratory analysis returned high concentrations of several pollutants in this area suggesting the interaction of mine waters and the possibility of poorly treated sewage discharges to the river. As a result, an individual mass balance was considered for sampling sites 32 to 34 and is detailed in graphs A.9, A.10, A.20 and A.21 in Appendix A.

- 56 - This found a number of pollutant spikes at locations 33 and 39. Upstream of 33 is Arkwright colliery with several land draining tributaries contributing to the flow. Similarly, 39 is downstream of another tributary draining derelict mine land. It is clear that spikes at these points relate to the draining of mine land, much of which is barely grazed, well compacted and promotes sediment transport. Bardill (2011a) states that settling ponds upstream of 33 are ‘full to capacity due to sediment deposits’. This would promote pollutants reaching the watercourse and justify results seen here.

In April, there are significant trends in the plots of Pools Brook data. There is a very prominent peak at point 33 similar to those shown in figure 3.23. Via dilution from the STW adjacent to 33 or possible precipitation via conversion to insoluble oxides; concentrations and mass flux reduce. This is characteristic across the majority of metals and underlines the influence at point 33.

A graph of metal concentrations in Pools Brook 100 5

90 4.5

80 4

70 3.5

60 3

50 2.5

40 2 Mass in mg/s Massin

30 1.5 Concentration in mg/l in Concentration 20 1

10 0.5

0 0 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 Distance along river from source (m) Fe (mg/s) Mn (mg/s) Fe (mg/l) Mn (mg/l)

A graph of changes in nitrate and ammonium concentrations in Pools Brook 450 25

400 20 350

300 15 250

200 10

Mass in mg/s Mass 150 Concentrationin mg/l 100 5 50

0 0 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 Distance along river from source (m) Nitrate (mg/s) Ammonium (mg/s) Nitrate (mg/l) Ammonium (mg/l) Figure 3.23: Graphs of metals and nitrates/ammonium concentrations (mg/l) and masses (mg/s) for the Pools Brook tributary of the Doe Lea River in APRIL.

In July, there are similar trends in metal concentrations. The characteristic peak at point 33 remains in each case, however, a second peak is observed at point 39.

- 57 - This is perhaps due to the reduced flow; given tributary 37 has greater influence on the pollutant concentrations. As expected, as a result of lower flow, the concentrations within the river are higher and the masses lower along all of Pools Brook. Ammonium and nitrate reduce significantly however, suggesting that there influence is not tied to the mining pollutants. It would therefore aid the presumption that the peak in ammonium and gradual increase in nitrate would be a result of influences from Long Duckmanton STW. It can be said that sample point 33 is the key polluter for the Pools Brook even though the EA classify its status as „good‟.

Next, on reach 20-23 is a rise in metallic pollutants which is again uncharacteristic of flow. There is a similar rise in sulphate and chloride suggesting external influences. Researching the mining history of the catchment revealed this is the site of former collieries as shown on the catchment map in Appendix B. This reach lies on the former site of Glapwell opencast so mine water interactions are possible. Slight mass increases of manganese, iron, zinc, copper and trace metals enhance the likelihood of its occurrence. This may result from polluted groundwater reaching the river through the highly permeable alluvium layer which sits beneath the river in this location (NSRI, 2011). Although the effects are not hugely significant to the profile of metal masses along the river, it is apparent that these sorts of interaction occurs frequently and especially in the urbanised lower reaches where mining heritage neighbours the river. This is also expected to be the cause of a steady influx of mine related pollutants seen in the industrialised reaches of 34 to 42a.

Additional mine influences are seen adjacent to sampling site 5, where a discharge point for Silverhill Colliery has been known to produce ochreous staining in the river (Bardill, 2011). During the July analysis this mine drain was understood to be dry, though during April it was expected to be flowing. Therefore a mass balance analysis either side of this sample point was justified.

What was found was an increase in concentration and mass of metallic pollutants that would be expected in mine discharge at point 5 relative to point 3 upstream. Noticeable peaks in April were seen in iron, strontium, aluminium, manganese, lead and zinc, with a minor increase in copper relative to flow. This therefore supports the suspicions of mine interaction at this point. In the July analysis, the masses of metals

- 58 - were minimal due to the low flow of the river. However, the concentrations were significant as aluminium, copper, iron, manganese and strontium all recorded their highest concentrations over the whole catchment at this point. The peaks seen in the masses of the metallic pollutants are expected to be a result of filtering and treatment capabilities of a wet woodland located in Dovedale Wood between sampling sites 5 and 6. This is a natural area of slow flow with natural treatment abilities much like a constructed wetland. Wetlands can be very efficient for treating mine discharges and this also appears the case here with the reduction of metallic mass in the river due to its occurrence (Younger, 2001). However, the nature of ochreous staining in the river would suggest that these reductions are as a result of metals precipitating out of the river after reacting with oxygen in the river.

Finally, of the major concerns is a peak in nitrate at sampling point 11. Over both analyses, this point showed an uncharacteristic rise in nitrate concentrations, though didn‟t highlight any other problems. Concentrations for April peaked at 31.9mg/l („high‟ in EA classification) and 44.13mg/l for July rendering it „excessively high‟. This would be expected to be a result of agriculture within the close proximity or an M1 road drain just upstream. It is however something to consider further.

. 3.17 EFFECTS OF SEASONAL VARIABILITY ON WATER QUALITY IN THE DOE LEA:

The mass balance also enables a seasonal variability analysis to be performed. As there is only one data set for each season, it‟s difficult to do detailed statistical analyses on the information. However, the masses for each sampling event can be compared as the locations at which the samples were collected remained constant. Therefore, numerous plots of April against July have been created to look at variability of mass flux and relationships between the two events:

- 59 -

Figure 3.24: Plots of mass flux for each sampling location. The x-axis represents the masses for April’s analysis and the y-axis represents the masses for July’s analysis.

The 12 pollutants selected here have the most influence in the Doe Lea catchment. What is clear to see from comparing the April and July analysis is that more than half show excellent correlation as they have a regression R2 value of approximately 1. A further three have good correlation while the weakest two, phosphate and copper have a degree of relation. None have a spread that differs significantly between the April and July sampling events. Therefore, it can be said with confidence that there is a strong relation between masses across the two seasons. This is certainly a key area for further study and would be interesting to compare to winter values. This may be a result of the April and July weather exhibiting similar warm and dry conditions. However, it may also explain that discharges to the river are similar all year round.

- 60 - 4.0 DISCUSSION:

Initially, this investigation has established a range of concentration, flow and mass values across the catchment for many different organics, inorganics and metals. It has gone into greater depth than any previous study in the catchment in terms of establishing a spread of all possible pollutants over the entire catchment area. Similar, smaller scale projects that are run over a much greater length of time but sample in a much more specific area have allowed comparison of the experimental data to predetermined values. This long-term data presented by the Environment Agency (2011a) has proven similar to the values obtained from the Doe Lea Dip project. This has therefore given confidence in the analysis, collection and methodology of the investigation. Upon concluding that the information gathered was a fair representation of the natural river conditions, the data was used to analyse a variety of pollutants, their sources and method of alleviating the pollution problems.

In addition to the collection of water samples was the measurement of flow along the river. This was undertaken in order to validate the flow estimation models and to better understand the roles of groundwater, catchment precipitation and runoff on the flow conditions in the river. During both the April and July dips, flow in the river was described as ‘exceptionally low for the time of year’ by the EA (2011e/f) with flows of 34% and 43% of long term averages respectively. As the flows were so far from the mean for that time of year field measurements were essential to validate the estimations.

A comprehensive background study on the land use, soil types, geology, artificial contributions and previous catchment issues has allowed a thorough analysis to be undertaken. Following presentation of this analysis, conclusions have been drawn with regards to which areas of the catchment are high risk for pollutants. These are discussed in greater detail below.

- 61 - 4.1 THE MASS BALANCE ANALYSIS AND FINDINGS OF INTEREST:

A preliminary study by the Catchment Science Centre (CSC) (Lexartza-Artza et al., 2009) identified regions of the catchment believed to have the highest potential to be sources of nutrients, sediments and runoff (figure 4.1). By undertaking detailed background study, estimating flow and calculating mass flux of pollutants at each of the 50 sample points; a high-risk map was produced to compare to this preliminary study. As a result, conclusions can be established as to whether perceived high-risk areas match with those found in this investigation. A final catchment pressures map was then established for the Doe Lea catchment as displayed in figure 5.1.

Figure 4.1: Representation of high-risk areas from Lexartza-Artza et al. (2009) Doe Lea catchment preliminary study

The area defined between sample points 28 and 34 and showing significant pollution input to the river was also highlighted as being high risk in Lexartza-Artza et al‟s preliminary paper of the Doe Lea in 2009. In this paper the risk of diffuse pollution and runoff between 28 and 34 was the highest in the catchment and this is confirmed in the results of the mass balance that significant contributions to the river are occurring here. Due to the nature of the river, these masses of nitrate and phosphate are not greatly reduced over the remainder of the river course and are instead gradually added to from diffuse discharges. The key concerns for the EA at location 34 are that their classification for phosphate pollution increases from „moderate‟ to „very high‟ and rises for nitrate from „low‟ to „high‟. It is therefore clear that concern

- 62 - raised by the CSC is matched by the results of this investigation. In the drive to reach „high‟ biological status under the water framework directive targets by 2015, the subcatchment of site 34 requires some serious land management consideration.

At site 34 (area 3 in figure 4.1) we know that overflow of STW is occurring and leaving sewage on land (Bardill, 2011). Dilution of this and runoff to the watercourse is a contributor to the elevated nitrate and phosphate concentrations and mass flux. The land is also agricultural giving rise to the chance of fertilisers etc to reach the surface waters of the Doe Lea. Finally there is New Bolsover STW, serving a population of approx 11,000 and hence with high potential for nutrient pollution. The table in figure 3.22 shows the the jump in pollution levels are very significant and therefore would render it the most important influence in the entire Doe Lea catchment in my opinion. If indeed it does relate to STW influence, then the potential to alleviate the problem is high and perhaps not too difficult or expensive to implement.

It was also shown that sample point 33 produced significant signs of mine discharges having a detrimental effect on river quality due to the proximity with Arkwright Colliery. However, this appears to only be a part contributor to the river quality degradation. Mass balance analysis suggests large quantities of inorganic salts are measured at site 33 and again at site 39. In addition to these is a peak in ammonium which accounting the July analysis is most likely attributable to the adjacent STW. Therefore it is clear that there are several possible combinations of sources for the spikes in pollution concentrations seen here.

The laboratory analysis returned high concentrations of several pollutants typical of mine drainage and included increases in sulphate, metals and salinity. This is contrary to claims from the Coal Authority, who in communication declared that no direct discharges of mine water interact directly with any part of the Doe Lea watercourse (Coal Authority, 2011). They did suggest there may be minor interactions; though couldn‟t confirm any locations where this was expected. Nevertheless, it is clear from the water chemistry that mine related pollutants are entering the watercourse in variable quantities. This therefore promotes the need for

- 63 - further investigation and a feasibility study for remediation methods to be undertaken.

Although the July analysis produced variable results to April for the Pools Brook area; the trends were maintained at points 33 and 39. Thus, suggesting that the issues here are ongoing. A spike in concentrations at these points was maintained for metals and sulphate. However, the behaviour of nitrate and ammonium changed considerably; which has since been determined to Long Duckmanton STW adjacent to sampling point 33. It may be fair to conclude that mine influences are continuously affecting the river here and nitrogen influences are intermittent or a one off just seen in April.

If this influx of metals is from the ex-colliery site, then responsibility for it would lie with the Coal Authority; presuming it was a coal site. Whereas the Coal Authority assumes responsibility for coal mines, there are no authorities directly responsible for metal mines. As a result, Younger (2000) states that „ferruginous discharges outside of major coalfields are largely neglected and hence these discharges remain untreated. This may be the case here, though the Coal Authority appeared to have an active role in the sites within the Doe Lea catchment when they were contacted.

Nutrients also provide a key challenge to the catchment. Apart from the nitrate and phosphate pollution between points 28 & 34, there are high concentrations of nitrate around the upper reaches of the catchment close to the peripheries. In total, 4 sample points are classified as „high‟ or „very high‟ for both April and July in the EA water quality standards. In addition, for phosphate, 10 points were classed as ‟high‟ to „excessively high‟ in April with a reduction to 8 in July. Nitrate is particularly prominent in April at points 43, 47 & 48 in Hawke Brook, point 26 in Pools Brook and points 11, 27 & 29 in the Doe Lea. Some of these were seen again in July, however, no samples were returned for 26, 29 and 43; three of the key sites for April. Therefore it is not possible to confirm with confidence that the trends continued over both sampling events. The slowly permeable „dale‟ soil in the East of the catchment may be the trigger for the increased contribution of nitrates and phosphates to the river. Due to the soil nature, surface water is generally encouraged to runoff rather than infiltrate into the soil and this could be a key driver for nutrient influx at points

- 64 - 28-34 on the Doe Lea and 43-38 on Hawke Brook. Therefore, the ‘mix of free draining and semi-permeable soils’ (NSRI, 2011) is likely to be prominent in determining the characteristics of the catchment.

In the rural upper catchment, the provision of land drains is expected to be the main driver of detrimental effects to the river quality. This produces a pathway for runoff to rapidly reach the watercourse, potentially delivering diffuse pollutants and suspended solids directly to the river and contributing to flood risk. In the lower catchment, the greatly overgrown river channels would support the theory of uptake of nutrients for plant growth. This is supported by the steady decline of masses of phosphate over the most vegetated regions between points 36 and 51.

In terms of industrial drivers, it is expected that the channelisation of much of the urbanised lower catchment is detrimental for flow and ecology. When constructed, this would have led to habitat destruction and couple this with the abundance of weirs and industrial abstraction points and it is clear that the entire flow regime has been anthropogenically altered. At present there remains minimal or no industrial abstraction as the types of industry requiring abundant sources of water have since closed. What is seen in particular is pollution emanating from Holmewood industrial estate delivering high concentrations of zinc, nickel and cadmium to the tributary at point 15. This influence was prominent in both April and July and as the source of this pollution is easily definable, it should be straight-forward to monitor and reduce.

Comparison of results from this study with the conceptualised hypotheses of the CSC has proved rather different. However, this does not necessarily conclude that one is right and one is wrong. The high risk areas from the CSC study will be more applicable during the wetter months where runoff from agricultural land and washoff from urban road networks is intensified. It is expected that the selected high-risk areas will be validated during the winter period and perhaps it may be fair to conclude that they are largely not applicable to drier months. It is expected further study will reveal these areas as key and provide a profile of changes in high-risk areas over the course of the year.

- 65 - 4.2 SEASONAL VARIABILITY OF THE APRIL AND JULY DIPS:

Seasonal variability affects the catchment in a number of ways. Most obvious from this analysis is the river flow. The unusually dry conditions in 2011 produced lower than average flow in the Doe Lea and tributaries which is most likely supplied from groundwater and artificial contributions.

From the mass balance it was found that the mass flux of pollutants for April was in the region of 3 times the equivalent flux measured in July (figure 3.24). This was not confirmed across all of the compounds analysed, though many did result in straight line plots with high regression values suggesting good relationships. It is clear that there is a strong association between masses of contaminant across the seasons and it will be interesting to see if this continues for the winter analyses.

As the July analysis produced pollutant masses in the region of 1/3 for the equivalent river reach in April, runoff appears to be a key limiter of the pollutant masses within the rivers of the catchment. The greater quantity of runoff in April enabled a greater quantity of diffuse pollutants to reach the watercourse. However, the affects of dilution resulted in most pollutant concentrations to be noticeably lower in April compared to July. To build a full picture of the effects of the various seasons on pollutant masses within the river requires the further analysis of the winter samples. This would also reveal the effects of less intensive agriculture which is expected during the winter months. What can be concluded from the two analyses performed so far however is that there is a clear correlation between the April and July pollutant masses within the river. This perhaps suggests an equal and sustained discharge of pollutants to the river in each event.

4.3 EXPECTATIONS OF FUTURE DIPS:

From what has been so far, a good approximation can be made for the seasonal variation of the water quality effects in the Doe Lea. However, here are some of the expectations and hypotheses for future dips:

- 66 - o With the exceptional dry spell seen during this investigation it is expected to see a heavy flush of pollutants from urban and agricultural landuse during the next large and sustained precipitation event. As the prolonged wet season of autumn settles and washes pollutants from the soil surface and the unsaturated zone toward the river; it is expected to see higher pollutant masses during the November dip. Perhaps by November the majority of this diffuse pollution will have advected downstream. However, if a sufficient quantity has built up, in addition to the expected fertiliser application at harvest, it may produce prolonged effects within the river system. This has been seen in similar investigations such as that of Neal et al., (2010), where flushing of septic tanks, STW‟s and land storage resulted in a noticeable rise in diffuse nitrate and phosphate concentrations within the river

o Ultimately it is expected to see a much greater flux in seasonal variability during the winter months. The sampling undertaken so far has produced similar warm and dry conditions with well related results for April and July. It is expected that the prolonged wet period of the winter months will produce an interesting comparison to what has been presented already. The potential of the investigation is therefore yet to be reached and a full year‟s study will paint a solid picture of river conditions from which to develop recommendations for landuse management.

4.4 PROBLEMS ENCOUNTERED WITH TECHNIQUES, CONDITIONS, FINDINGS AND PREVIOUS WORK:

Overall the project has run smoothly and results have proved useful in determining the sources of poor water quality in the catchment. Certain aspects could be improved and as such as short appraisal of work is covered below. It has been stressed how important flow measuring is to the project. However, when measuring the flow in the river, the impeller of the Geopacks flowmeter used to estimate flow velocity did not easily measure slow velocities. As a result, some flows did not induce rotation of the impeller even though it was obvious that the water was flowing. This is expected to affect the accuracy for measurements of flow across the

- 67 - catchment and a more sensitive flowmeter would be suggested for future measurements.

In addition was the inaccessibility to many portions of the river network. Many of the upper reaches either had flow too shallow to measure or were so overgrown; that it was unfeasible to access the river. Further down the catchment, in addition to the overgrowth of the river was the effects of urbanisation on the river. Much of the lower reaches are channelised with high sided concrete banks making access near impossible. Other areas are private land that cannot be easily accessed. The majority of water samples could be collected with the use of extension rods, however gaining safe access to the river in order to measure the flow velocity and water cross-section was impractical in many places. As a result, only eight flow measurements were taken in the catchment. An estimate was developed with confidence from the measurements collected; however, it would be useful to have a few measurements for the upper catchment also to determine flow in the smaller tributaries.

Similarly, estimations of inputs from STW‟s were crudely established using a water usage per person per day and calculated with population to estimate a discharge. In consideration of deadlines, it was not feasible to wait any longer for this information from Yorkshire Water. Hence, the population equivalent estimations were derived. Also, two springs were measured in the East of the catchment and in terms of practicality, all known springs were presumed to discharge the mean of these two flows.

Finally, the unseasonable conditions of the spring sample period are expected to have had a significant skewing effect on the data. It would be useful to reanalyse the spring samples next April to see the variation when conditions are average for the time of year.

- 68 - 4.5 HOW CAN THE PROJECT BE IMPROVED FOR FUTURE DIPS?

Most important to the integrity of the project was that the samples were correctly collected by the volunteers. When attempting to measure flow a week after the July dip, site 41 was dry. In the July analysis, a sample for site 41 was returned which rendered the question from where it was collected? It was probably taken from the reed bed at the end of the tributary which is permanently wet. However, it is somewhat stagnant and may produce a skewed result in the analysis. Therefore, a plan was devised to provide all volunteers with a map to mark a cross exactly where their sample was taken from. Then the judgement on the relevance of the sample can be decided by the individuals analysing the results. To that end, there is better control of results and their relevancy to the overall quality issues can be better determined.

The importance of accurately measuring flow became particularly apparent in the July analysis when field measurements were taken to justify and calibrate the flow prediction model. Therefore it would be suggested to build field flow measuring into the sampling procedure to get a believable estimate of mass flux across the catchment.

In the April and July analysis, two main high-risk areas have been defined at river reaches 28-34 and 29-33. At each location, there are a number of potential sources of pollution. It would therefore be beneficial to include at least one extra sampling site between the points to better identify these sources. Each have a STW halfway between the points, so including a sample point upstream of these STW‟s would be beneficial to the determination of pollutant sources. In addition, the sampling locations on Hawke Brook do not make mass balance analysis easy as points lie on tributaries and not the main stream. Hence the results of mixing have to be estimated and it would be better to include more points on the main trunk to establish the effects of each of the smaller tributaries to the main flow. There appears to be a shortfall of certain pollutant masses which could be better located had there been additional sampling points been on the main stream.

- 69 - 4.6 FURTHER STUDY:

The Doe Lea Project encompasses much more than has been studied here. At this stage, just half of the sampling has been completed. The remainder of the study is hoped to be a verification of what has been seen in the first two samplings periods. However, many parameters are expected to change significantly as land use changes over the winter months. Less agricultural practices may result in reduced nutrient runoff, however, other pollutants will increase in concentration such as road salts. The proximity of major roads and the M1 motorway is expected to provide interesting results for pollution of road wash-off pollutants. The winter usually provides longer, wetter periods driving transport of diffuse pollution from a greater array of sources such as the urbanised landuses in the catchment. As soil is known to be easily waterlogged, the winter months will have a significant effect of increasing runoff. Therefore, although recommendations can be put forward at this stage, the full programme should be analysed to suggest the most efficient land management solutions. What can be recommended at this stage are still viable options, though it is yet to be seen if these applications are of equal efficiency when the effects of seasonal variability are clearer.

In a study like this, there is useful information that is simply not feasible to gather data for. One important variable investigated by Barnett et al. (2008) is the temperature of discharges to the river. Much consideration has been placed on examining the concentrations of nutrients, metals and organics in discharges; however temperature fluctuations can be problematic. Most ecological systems are sensitive to rapid temperature changes. Barnett et al (2008) found in a recent study that altering the temperature of a watercourse by ‘more than 1-2 degrees Celsius’ could inhibit detrimental effects on the ecological value of the watercourse. In the Doe Lea catchment, many discharges emanate from a range of sources. Temperature of these discharges is highly susceptible to change as industrial, mining and STW discharges will vary considerably. There is currently no understanding of discharge temperatures and this may be contributing to the poor ecological value assigned to the river. Hence, further investigation into the control of discharge temperatures would be a sensible and viable method of further study to enhance the robustness of our findings.

- 70 -

Another parameter not considered in this project but considered in previous Doe Lea studies is suspended solid within the river. Suspended solids (SS) are important for several reasons. Ferrier & Ellis (2000) suggest they are pollutants in their own right and can affect economic potential of water systems via sedimentation and loss of storage capacity etc. Suspended solids could be especially problematic in the catchment as adsorption of pollutants to solids such as toxic metals and nutrients can transport the pollutants freely around the river system (Ferrier & Ellis, 2000).

Although agriculture and rural sources can be high contributors of SS; urban sources such as construction can contribute extremely high quantities. It may be worth developing this into the investigation as the catchment is undergoing a high degree of redevelopment of colliery waste land. This is especially prominent around Markham Vale between sample point 34 and 42a. Another urbanised source of SS is urban runoff. This is mainly captured in the surface water drainage system, though some can directly reach the watercourse.

The turbidity of the samples collected so far has been good with all but two of the samples being visually clear. The samples that were returned cloudy are expected to be generated from poor collection of the sample and collection of bed sediment during sampling. Either way, it would provide an interesting area of further study for the following two sampling events.

Finally a key consideration for further study would be better understanding of groundwater interactions with the water course. It is known that the primary aquifer is on the East of the catchment and this feeds the springs and issues contributing to river flow. However, the interaction of groundwater from infiltration to river recharge is not known in detail. It would be useful to establish this, especially in relation to mine discharges where it is possible that polluted groundwater is providing the pathway for pollutants to reach the river system. Also the groundwater quality as a result of nitrate, phosphate and metallic pollution in the catchment would be of great assistance.

- 71 - 5.0 CONCLUSIONS:

During the April and July analysis of the Doe Lea catchment, a significant step has been taken in establishing why the water quality in the catchment is so poor. This is perhaps not a true representation of the catchment due to unseasonably dry conditions, however, does provide and excellent level from which to develop solutions to the quality problems. The analysis proceeding into the winter months will define how well the spring and summer sampling has been in establishing and mapping the quality degradation in the catchment. As discussed, it is expected to see greater fluctuation of pollutant concentrations and masses in the winter months due to increased runoff and river flow. How these affect the water quality, sources and interaction of pollutants will be key to the overall success of the project. Nevertheless, the key findings of this project and how they relate to surface water quality in the Doe Lea catchment are highlighted below:

In terms of nutrients, there is one clear location driving the poor water quality of the river. This is the reach between sample points 28 and 34 in the Bolsover region, midway down the catchment. Its source is believed to be from discharge from Bolsover STW, though the steep nature of the catchment could promote nutrient runoff from the agricultural/urban landuse. This was highlighted previously as area 3 in the preliminary paper and is the most significant concern to river quality in the Doe Lea catchment. Solutions could include improving the treatment of New Bolsover STW or introducing measures controlling nutrient application to land. Either way, further analysis is required over the remaining two dips to determine the exact source of the nutrient influx and see how the effects of this pollution vary over the seasons. Adding an additional sampling point to aid determination of the sources is strongly recommended.

With the exception of the discharges at point 34 the pressures relating to nitrate arise around the agricultural upland periphery of the catchment. This primarily is to the north-east at point 47 & 48, to the west at 26 & 29 and in the south-west at points 9 & 12 respectively. Phosphate is less intrusive in the catchment except for elevated

- 72 - levels as a result of the large discharge between points 28 and 34 as already discussed.

The catchments long history of mining influence is also key in the improvement of water quality. Although the Coal Authority (2011) have stated that no mine waters surface in the area or discharge directly into the rivers of the catchment, it is clear that some minewater interaction is occurring. There are the characteristic signs of mine drainage across the catchment; some of which comes from the collieries and some from the abundance of spoil heaps that litter the landscape. The signs include increased quantities of characteristic metals, sulphate and alkalinity. Much of the mining heritage related to coal and indicators of this include iron, manganese and aluminium. These are typical of coal mine drainage and have been observed in elevated concentrations in close proximity to ex-colliery sites across the catchment.

As suggested previously, the particular area of concern with regards to mine drainage is sampling point 33. Typical pollutants are also visible at site 41 which lies on an anthropogenically created mine waste spoil heap at Markham Tip. Key indicators such as chloride suggest that colliery waste is deteriorating quality and causing leaching of pollutants to surface waters. There is also expected influence between sample points 34 and 42a where pollutant masses increase even though there are no known point discharges to the river. In the area, the river flows through Bolsover, Markham and Erin collieries and there is potential for interaction via runoff or polluted groundwater in the close vicinity (appendix B).

In the upper catchment is a noticeable influence from Silverhill Colliery. This is mainly due to the low flow in the tributary here and therefore intensifies the concentration of mine related pollutants. As a result, the masses are not as significant as other areas of the catchment, though mining influences are still apparent and may intensify during wetter periods of the year. Additionally, there is the Oxcroft coal depot in the north-west of the catchment where a shortfall of metal masses may be made up by discharges from the site. Again this would require further analysis as the tributary flows here have been so low over the period of investigation.

- 73 - Finally, there appear to be many minor effects on river quality from industry in the catchment that do not contribute significantly enough to pursue. That is with the exception of sampling location 15 where catchment high concentrations of zinc, nickel and cadmium were established. This is one recommendation already being acted upon by the National Trust (NT). Thanks to the extensive knowledge the NT have of the catchment; many spikes on the analysis could be acted upon immediately. In some cases, the NT had prior expectations of the results and as soon as the concentrations they expected were presented, they had justification to implement management methods to reduce pollutants in the watercourse (Bardill, 2011). This was particularly evident at point 15 where the significant industrial pollution has been traced to a plating manufacturer in the Holmewood industrial estate upstream of the sampling point. This is currently being pursued by the National Trust to prevent further pollutants reaching the rivers of the Doe Lea. It is hoped that over the remaining two dips the pollution emanating from this source will diminish as a result of this intervention.

Overall, the impacts of mining, agriculture, urbanisation and industry are severely stressing water quality. Comparing the two analyses of April and July helped to determine what trends continued through the seasons and which may be more likely to be intermittent or one-off events. It was determined that contaminant masses within the river were approximately 3 times higher in April than in July. However, the correlation of mass fluxes between April and July for the fifty sampling points was very strong. It was especially strong for chloride, sulphate and some heavy metals and suggested that the mass of pollutants in the river in July was proportional to masses for the same point in April. This could well suggest that there is a steady continuous supply of pollutants entering the river across the two seasons. Whether this is applicable for all seasons is yet to be seen and is a key area of further study for the remaining analyses. Generally, the pollutant concentrations were higher in July than April for the fifty sites. Though, this would be expected due to the lower river flows in the summer. Nitrate and phosphate showed less correlation with R2 values of 0.88 and 0.56 respectively. This reduced association between sampling events would be expected and support the random nature at which non-point diffuse agricultural pollution enters the watercourse.

- 74 - 5.1 SUMMARY OF SUGGESTED CHANGES TO FUTURE SAMPLING:

The first two Doe Lea dips have proved successful in mapping pollutants across the catchment. There are suggestions to improve future sampling to produce a better analysis of catchment characteristics and the following should be implemented for optimum results:

o Continuation of field flow measurements to validate rainfall-runoff flow estimation model. This was key in July and delivers confidence in findings whilst also providing another interesting dataset for seasonal variation

o Editing of sample points especially those in Hawke Brook where sampling is done on tributaries rather than the main stream. Interaction of streams could therefore be better analysed with amended locations

o Addition of sampling points between 28 & 34 and 29 & 33 to aid definition of the sources of the spikes in pollution seen at these two locations

o Ensure volunteers mark on a map the exact location from where the sample was taken from in order to ensure information is relevant

o Develop an improved estimation of STW discharges and attempt to locate and measure mine discharges in the field

5.2 HOW DO THE RESULTS COMPARE TO THE INITIAL HYPOTHESIS?:

At the start of the project, five hypotheses were stated regarding the expectations of the project and the drivers of poor water quality in the catchment. These are reviewed below and discussed in relation to how well they match the findings for the report:

- 75 - Hypothesis: Result:

One: As expected, it has proved to be the case that nutrients most likely arising Water quality degradation is from agriculture are increasing nitrate concentrations in the upper due to the application of catchment. This is in addition to the major influx of nutrients observed at fertilisers, mine discharges sample point 34 which has been attributed to STW discharges or nutrient and sewage treatment works runoff. Finally, among others, site 33 has shown strong signs of mining discharges: discharges and is the key concern within Pools Brook.

The road network appears to have had a greatly reduced effect than what would be expected. This is most likely due to the drier months of Two: sampling producing less runoff and limiting the availability of pollutants The road system, particularly to the river. It is expected that contributions of diffuse highway related the M1 will have a strong pollutants such as hydrocarbons, PAH‟s and salts will peak in the two influence on water quality: remaining sampling events when prolonged wet periods will allow transport of pollutants to the Doe Lea watercourse

Three: This has proven to be true and very significant in terms of the overall Water quality is noticeably water quality. The hypothesis was geared towards the urbanisation of the degraded downstream of lower half catchment being the main concern. It is however a single Bolsover: source that is causing the significant water quality issues downstream rather than the industry and mining landuse as initially expected

Four: This is still expected to be the case, though without any data for periods Effects of agriculture will be outside of the spring and summer sampling, it is not possible to confirm. more prominent in the April This is an example where further analysis and progression into the project and July analysis: is required.

Five: This was certainly the case in the July analysis when compared to the Pollutant concentrations will April findings. Flow was significantly lower in July than in April and this increase in summer due to proved to increase concentrations. Mass fluxes in April were in the region reduced flow: of three times the value for equivalent sampling location in July. Figure 5.1: A summary of the project conclusions in comparison to initial hypotheses for the investigation.

5.3 WHY IS THE WATER QUALITY IN THE DOE LEA SO POOR: A FINAL SUMMARY:

Concluding the investigation and analysis of the April and July Doe Lea Dip sampling data has revealed a number of findings. There are clearly many different drivers that affect the water quality in the catchment and these vary depending on the climatic conditions at the time of sampling. The map below is a plot of high-risk areas of the catchment developed from information available to date. Their location and why they are of particular concern is explained also:

- 76 - 5 - Elevated metals believed to be mine drainage from Silverhill Colliery

11 - Significant peak in nitrate with concentration reaching 44mg/l. Source is either agriculture or M1 drainage

15/16 - Increase in zinc, nickel and cadmium emanating from Holmewood industrial estate

24 - A624 road drainage

26/27/29 - High nitrate from agricultural units on the catchment periphery

28-34 - Discharge of significant quantities of nitrate and phosphate

29-33 - Drainage from Arkwright Colliery

39 - Drainage from Arkwright Tip

43/47/48 - High nitrate from agricultural landuse on catchment periphery

Figure 5.2: Plot of the most pressured sub-catchments from analysis of the April and July Doe Lea Dip samples. [Blue = mining issues, Green = nutrient issues, Red = industrial issues, Yellow = nitrate issues]

There are numerous additional causes for concern across the catchment, however the above are suggested as the most substantial from the available information thus far. Again, it is expected for this to change for the November and February analyses due to the wetter conditions and the greater potential for diffuse transport to the watercourse. It is anticipated that the worst effects of pollution are yet to be seen as many of the road and field drains were dry in the July analysis. These are predicted to be substantial pathways for large quantities of pollutants though will only flow when there is sufficient rainfall and subsequent drainage to fill them. It is therefore both appropriate and important to reiterate that the findings of this paper only relate to the spring and summer sampling and are not a representation of annual water quality changes. This paper does however set a level from which to compare winter

- 77 - values and to begin management methods to alleviate pollution in the river and to block known polluting sources.

In conclusion, to answer the initial question of why is the water quality in the Doe Lea is so poor; it can be concluded that the following issues are driving the deterioration:

Types of Rank Nature of pollution problem Location Degree of severity Expected causes pollutant

A significant increase in Phosphate concentrations nutrients is observed leading to Two possible sources: increased to five times excessive concentrations Nitrate and o STW discharge to the river 1 28 to 34 maximum for EA standards. breaching EA standards for the Phosphate o Land runoff from the steep Nitrate increased to remainder of the river until diluted sloped east catchment „excessively high‟ by Pools & Hawke Brook Spikes in concentration of o Drainage from the colliery Metals typical Definite noticeable rise in characteristic mine drainage o Poorly vegetated and easily of mine metallic pollution which is pollutants were observed at points eroded land increasing runoff 2 29 to 39 discharge, salts, highest in the catchment. 33 and 39. Upstream of these o Leaching from spoil heap sulphate, Quality still defined as „good‟ points is fed by land drains from o Polluted groundwater alkalinity in EA ecological classification Arkwright Colliery o STW discharge Agricultural practices in the upper Concentration in April at 47 Agricultural practices: catchment and peripheries 26, 27, 29, breached nitrate directive o fertiliser application 3 Nitrate contributing elevated concentrations 43, 47 & 48 maximum. Problematic in Hawke o agricultural waste heaps of nitrate to low flow rural streams Brook and west of Doe Lea o land and field drains Industrial discharges especially The highest concentration of Metals: zinc, Untreated discharges from evident at Holmewood industrial zinc and nickel were recorded 4 15 & 16 nickel & industrial estate at estate and in lesser severity at 15, three times higher than cadmium Holmewood throughout the lower catchment anywhere else in the catchment Nitrates increase by 25mg/l and Sites fall at discharge points Road drainage points throughout 43mg/l in April and July Nitrates, from M1 motorway and A624 the catchment coincide with one respectively at site 11. A 5 11 & 26 hydrocarbons, road drains. Pollutants off spikes in nitrates and other concentration of 41mg/l was salts and PAH‟s presumed to derive from highway pollutants returned for site 26 with no diffuse road pollution sample returned for July

Figure 5.3: A concluding table of key drivers of water quality degradation in the catchment

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- 81 - o Haygarth, P., Dils, R., and Leaf, S. 2000. Phosphorous. In: CIWEM, 2000. Diffuse Pollution Impacts: The Environmental and Economic Impacts of Diffuse Pollution in the UK. Lavenham, Suffolk: Terence Dalton Publishers Ltd. Ch.8, pp 73-84 o Heathwaite, A.L., Burt, T.P., and Trudgill, S.T. 1993 Overview – The nitrate issue. IN Burt, T.P., Heathwaite, A.L., and Trudgill, S.T. 1993. Nitrate: Processes, Patterns and Management. Chichester: John Wiley and Sons. Ch.1. pp 3-22 o Hiscock, K.M., Lovett, A.A., Brainard, J.S. and Parfitt, J.P. 1995. Groundwater vulnerability assessment: two case studies using GIS methodology. Journal of Engineering Geology & Hydrogeology, Vol 28(2) pp179-194 o Huntley, D. Leeks, G. and Walling, D. 2001. Land-Ocean interaction: Measuring and modelling fluxes from river basins to coastal seas. IWA publishing: London o IGS. 1981. Hydrogeological Map of the Northern East Midlands: 1:100,000. Institution of Geological Sciences: London. o Jarvie, H.P., Whitton, B.A., and Neal, C. 1998. Nitrogen and phosphorous in east coast British rivers: Speciation, sources and biological significance. The Science of the Total Environment. Vol 210/211. pp 79-109 o Jay, M. 1997. Operation manual for stream flowmeters and anemometers. Geopacks: Devon, UK o Kiely, G. 1997. Environmental Engineering. Singapore: McGraw Hill o Lake, I. Foxall, C. Lovett, A. Fernandes, A. Dowding, A. White, S. and Rose, M. 2005. Effects of river flooding on PCDD/F and PCB levels in cows' milk, soil, and grass. Environmental Science & Technology. 39(23), pp.9033-9038. o Lexartza-Artza, I., Lerner, D., and Tkachenko, N. 2009. Preliminary study of the Doe Lea catchment for the Doe Lea project. Catchment Science Centre. The University of Sheffield. o Marsh, T. J., and Hannaford, J., 2008. UK Hydrometric Register: hydrological data UK series. Centre for Ecology & Hydrology (Natural Environment Research Council), Wallingford. o MET Office, 2011. UK climate summaries: UK actual and anomaly maps [online] Exeter, UK. Available from: http://www.metoffice.gov.uk/climate/uk/anomacts/ [Accessed on 5 July 2011] o MET Office, 2011a. UK climate series: UK rainfall, sunshine and temperature anomaly graphs [online]. Exeter, UK. Available from: http://www.metoffice.gov.uk/climate/uk/anomalygraphs/ [Accessed on 5 July 2011] o Naismith, I. Wyatt, R. Gulson, J. and Mainstone, C.P. 1996. The impact of land use on Salmonids: a study of the River Torridge Catchment. R&D Report 30. National Rivers Authority: Bristol

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- 83 - o Water UK, 2011. About the Water Framework Directive [online]. Available from: http://www.water.org.uk [Accessed on 22 June 2011] o Younger, P.L., 2000. Iron. In: CIWEM, 2000. Diffuse Pollution Impacts: The Environmental and Economic Impacts of Diffuse Pollution in the UK. Lavenham, Suffolk: Terence Dalton Publishers Ltd. Ch10, pp 95-104 o Younger, P.L., 2000a. Predicting temporal changes in total iron concentrations in groundwater flowing from abandoned deep mines: a first approximation. Journal of Contaminant Hydrogeology. Vol 44 (1), pp 47-69 o Younger, P.L., 2001. Mine water pollution in Scotland: nature, extent and preventative strategies. The Science of the Total Environment. Vol 265 (1-3), pp 309-326 o Whendee L.S., Herman, D.J., and Firestone, M.K. 2001. Dissimilatory nitrate reduction to ammonium in upland tropical forest soils. Journal of Ecology. Vol 82. pp 2410–2416 o Williams, A.G., Borthwick, M.F., Mtika, E., Ternan, J.L. and Sullivan, A. 2004. The influence of changes in farming patterns on the runoff characteristics of the River Camel, Cornwall, UK. Hydrology: Science and practice for the 21st century: Proceedings of the British Hydrological Society Conference. Imperial College London, 12-16 July 2004. o Wood, S.C., Younger, P.L., and Robins, N.S., 1999. Long-term changes in the quality of polluted minewater discharges from abandoned underground coal workings in Scotland. Journal of Engineering Geology & Hydrogeology. Vol 32 (1), pp 69-79

- 84 - Appendix A: Index of parameters analysed and plot of results (April & July)

A.1 Analysis of water samples (April sampling): Over the 50 sampling sites and utilising the laboratory equipment available at the university, it was possible to collect a diverse range of data from the water samples. A full list of the compound concentrations determined in the water samples for April is included below:

Minerals: Metals: PAH’s: Other: Flouride Silver Naphthalene BOD5 Chloride Aluminium Acenaphthylene pH Nitrite Arsenic Acenaphthene Bromide Barium Fluorene Nitrate Beryllium Phenanthrene Phosphate Bismuth Anthracene Sulphate Cadmium Fluoranthene Sodium Cobalt Pyrene Ammonium Cromium Benz[a]anthracene Potassium Copper Chrysene Magnesium Iron Benzo[b]fluoranthene Calcium Manganese Bezo[k]fluoranthene Molybdenum Benzo[a]pyrene Nickel Dibenz[a,h]anthracene Lead Benzo[ghi]perylene Tin Indeno[1,2,3-cd]pyrene Rubidium Selenium Strontium Tellurium Thallium Vanadium Zinc

Pollutants showing the most recognisable trends are displayed in detailed location plots over the page:

- 85 - Figure A.1: Plots of Al, NH4, BOD and Cd, showing catchment concentrations for April

- 86 - Figure A.2: Plots of Cl, Cr, Cu and Fe, showing catchment concentrations for April

- 87 - Figure A.3: Plots of Pb, Mn, Ni and NO3, showing catchment concentrations for April

- 88 -

Figure A.4: Plots of pH, P, SO4 and Zn, showing catchment concentrations for April

- 89 - A.2 Flow estimation for April sampling:

Note: Flow presented in m3/s

Figure A.5: Plot of estimated flow in the catchment for April in m3/s. Low flows are represented by small green icons and large red icons represent highest flows. The sphere sizes in the left image are proportionate to the quantity of flow in that particular location.

- 90 - A.3 Laboratory results for April sampling:

Figure A.6: April laboratory results for inorganics and metals

- 91 - A.4 Mass balance graphs for April:

Figure A.7: Graph of April mass balance on the main Doe Lea River. Dotted lines represent concentration (mg/l) and mass flux (mg/s) for each of the river reaches. Solid lines represent expectations of pollutant contributions to river to locate sources and estimated quantities contributed to the river.

- 92 -

Figure A.8: Graph of April mass balance on the main Doe Lea River. Dotted lines represent concentration (mg/l) and mass flux (mg/s) for each of the river reaches. Solid lines represent expectations of pollutant contributions to river to locate sources and estimated quantities contributed to the river.

- 93 -

Figure A.9: Graph of April mass balance in Pools Brook. Dotted lines represent concentration (mg/l) and mass flux (mg/s) for each of the river reaches. Solid lines represent expectations of pollutant contributions to river to locate sources and estimated quantities contributed to the river.

- 94 -

Figure A.10: Graph of April mass balance in Pools Brook. Dotted lines represent concentration (mg/l) and mass flux (mg/s) for each of the river reaches. Solid lines represent expectations of pollutant contributions to river to locate sources and estimated quantities contributed to the river.

- 95 -

Figure A.11: Graph of April mass balance in Hawke Brook. Dotted lines represent concentration (mg/l) and mass flux (mg/s) for each of the river reaches. Solid lines represent expectations of pollutant contributions to river to locate sources and estimated quantities contributed to the river.

- 96 - A.5 Analysis of water samples (July sampling):

A full list of the compound concentrations determined in the 50 water samples for July is included below:

Minerals: Metals: PAH’s: Other:

Fouride F Silver Ag Naphthalene BOD5 Chloride Cl Aluminium Al Acenaphthylene pH Nitrite NO2 Arsenic As Acenaphthene Bromide Br Boron B Fluorene Nitrate NO3 Barium Ba Phenanthrene Phosphate P Beryllium Be Anthracene Sulphate SO4 Bismuth Bi Fluoranthene Amonium NH4 Cadmium Cd Pyrene Potassium K Cobalt Co Benz[a]anthracene Magnesium Mg Copper Cu Chrysene Calcium Ca Iron Fe Benzo[b]fluoranthene Gallium Ga Bezo[k]fluoranthene Lithium Li Manganese Mn Molybdenum Mo Nickel Ni Lead Pb Rubidium Rb Selenium Se Strontium Sr Tellurium Te Thallium Tl Uranium U Vanadium V Zinc Zn

Pollutants showing the most recognisable trends are displayed in detailed location plots over the page:

- 97 -

Figure A.12: Plots of Al, NH4, BOD5 and Cl showing catchment concentrations for July

- 98 -

Figure A.13: Plots of Cr, Cu, Fe and Pb showing catchment concentrations for July

- 99 -

Figure A.14: Plots of Mn, Ni, NO3 and pH showing catchment concentrations for July

- 100 - Figure A.15: Plots of P, Sr, SO4 and Zn showing catchment concentrations for July

- 101 - A.6 Flow estimation for July sampling:

Note: Flow presented in m3/s

Figure A.16: Plot of estimated flow in the catchment for July in m3/s. Low flows are represented by small green icons and large red icons represent highest flows. The sphere sizes in the left image are proportionate to the quantity of flow in that particular location.

- 102 - A.7 Laboratory results for July sampling:

Figure A.17: July laboratory results for inorganics and metals

- 103 - A.8 Mass balance graphs for July:

Figure A.18: Graph of July mass balance on the main Doe Lea River. Dotted lines represent concentration (mg/l) and mass flux (mg/s) for each of the river reaches. Solid lines represent expectations of pollutant contributions to river to locate sources and estimated quantities contributed to the river.

- 104 -

Figure A.19: Graph of July mass balance on the main Doe Lea River. Dotted lines represent concentration (mg/l) and mass flux (mg/s) for each of the river reaches. Solid lines represent expectations of pollutant contributions to river to locate sources and estimated quantities contributed to the river.

- 105 -

Figure A.20: Graph of July mass balance in Pools Brook. Dotted lines represent concentration (mg/l) and mass flux (mg/s) for each of the river reaches. Solid lines represent expectations of pollutant contributions to river to locate sources and estimated quantities contributed to the river.

- 106 -

Figure A.21: Graph of July mass balance in Pools Brook. Dotted lines represent concentration (mg/l) and mass flux (mg/s) for each of the river reaches. Solid lines represent expectations of pollutant contributions to river to locate sources and estimated quantities contributed to the river.

- 107 -

Figure A.22: Graph of July mass balance in Hawke Brook. Dotted lines represent concentration (mg/l) and mass flux (mg/s) for each of the river reaches. Solid lines represent expectations of pollutant contributions to river to locate sources and estimated quantities contributed to the river.

- 108 -

A.9 Comparison of April and July sampling results:

Figure A.23: Graph comparing concentration (mg/l) and mass flux (mg/s) for April and July for various pollutants in the main Doe Lea River

- 109 -

Figure A.24: Graph comparing concentration (mg/l) and mass flux (mg/s) for April and July for various pollutants in the Pools Brook tributary of the Doe Lea River

- 110 - Appendix B:

Figure B.1: Detailed map of the North half of the Doe Lea Catchment

- 111 -

Figure B.2: Detailed map of the South half of the Doe Lea Catchment

- 112 - Appendix C:

River sediment monitoring and dioxin analysis in the Doe Lea: A literature survey of Environment Agency studies between 1991 and 1998.

The most noticeable pollution outbreak in the Doe Lea and perhaps the trigger for further analysis projects such as this one is the dioxin pollution of the early 1990‟s. Since its release from Coalite Chemicals into the Doe Lea watercourse at Bolsover, Derbyshire, the exceptional dioxin levels prompted several detailed surveys into its environmental impact. Most of the surveys completed by the Environment Agency and the National Rivers Authority are geared in search of a best practicable environmental option (BPEO) for treatment and remediation of the dioxin pollution.

The pollution was first noticed in the summer of 1991 when locally produced milk was found to be contaminated with dioxins (Lake et al., 1995). The Ministry for Agriculture, Fisheries and Food (MAFF) were the first to investigate the sources and environmental impacts of the dioxin pollution in relation to the milk findings. As this grazing land was often flooded it triggered a river quality investigation by the National Rivers Authority (NRA). This, as reported by Scott Wilson (1998) developed into ‘one of the most comprehensive and detailed monitoring programmes ever undertaken by the NRA’. The pollution was successfully traced back to Coalite Chemicals and the company was prosecuted under the Health and Safety at Work Act, 1974 (Schoon, 1994).

Dioxins and furans are extremely toxic to the environment. Officially termed polychlorinated dibenzo-p-dioxins (PCDD‟s) and polychlorinated dibenzofurans (PCDF‟s), they are usually referred to as dioxins (NRA, 1995; Scott Wilson 1998). Of 210 different types, only 17 are classed as extremely toxic with Scott Wilson reporting tetrachlorodibenzo-p-dioxin, 2,3,7,8 (TCDD) as the most toxic to aquatic organisms. The current method of representing concentrations is to express them as a toxic equivalent; or simply i-TEQ. The values are referred to as either ng/g or ng/kg.

- 113 - To retain continuity, ng/kg will be adopted for representing the i-TEQ values for this paper. To put dioxin pollution into context, Lilley (2002), stated how ‘dioxin is probably the most toxic synthetic chemical known to science‟. It is extremely detrimental to human health and ecological value in receiving waters such as the Doe Lea River.

The source of the pollution was believed to arise from a leak at the biological effluent treatment plant (BETP) at Coalite Chemicals. At the time of the incident, a photograph was taken of the BETP pipes leading directly into the Doe Lea River. This is widely available through internet image searches though cannot be represented here due to copyright reasons. A link has been included in the references under SPL (2011). It can be seen that the pollution, which is leaking in the right of the photo, has had an immediate detrimental effect of the ecological value of the river as much of the bank vegetation appears to be dead.

Coalite Chemicals produced by-products from the coal readily mined in the close vicinity. The NRA (1995) report that this included creosote, chlorinated oils and chlorinated phenols. The BETP at the site was constructed to treat all effluent from the site to a level that would meet discharge consents before discharging to the Doe Lea. This was reported to be a two-stage activated sludge plant where dried solids were extracted for incineration and filtered final effluents were released into the receiving Doe Lea watercourse. River quality monitoring identified the site as the source of the leak. Investigations by the NRA found that upstream of the pollution site, dioxin levels were 10 i-TEQ ng/kg and downstream were 64000 i-TEQ ng/kg. Concentrations within the activated sludge of the Coalite BETP were 210000 i-TEQ ng/kg and as a result, a solid case against Coalite Chemicals was formed (NRA, 1995).

The hydrological characteristics of rivers caused the plume of dioxins to spread downstream into the Sheffield and South Yorkshire Navigation (SSYN). Advection of sediment downstream of the Doe Lea, Rother and Don resulted in deposition of dioxin sediment in the low velocity areas of the waterways. NRA (1995) suggested that the highest dioxin concentrations had settled behind the abundance of weirs in the network and that this supported the „do-nothing‟ approach to remediation.

- 114 -

Km Oct Mar Mar Feb Jan Sep Nov Location River from 1991 1993 1995 1996 1997 1997 1997 source U/S of Coalite Doe Lea U/S 10 9 18 11 7.1 15 16 Chemicals Buttermilk Lane Doe Lea 0 64000 45311 1211 550 290 180 350 Markham Gauging Doe Lea 1.6 - - 3660 350 1100 1100 590 Station U/S of M1 Doe Lea 1.8 54000 7407 529 - - - -

Netherthorpe Doe Lea 4.4 26000 12303 467 330 560 540 360

Renishaw (Rother) Rother 9 1500 303 - 27 120 53 97

Canklow Rother 27.1 1700 426 - 93 320 96 360

Figure C.2: Dioxin concentrations in ng/kg iTEQ for the Doe Lea and Rother downstream of Coalite Chemicals as recorded by the NRA & EA between 1991 and 1998 (After EA, 1997; NRA, 1995; Scott Wilson, 1998)

Figure C.3: Plot of the locations of dioxin water quality measurements between 1991 and 1998

- 115 - A chart of dioxin concentrations at various points downsteam of Coalite Chemicals from 1991-1998 70000

60000

50000 U/S of Coalite Chemicals 40000 Buttermilk Lane 30000 Markham Gauging Station

(i-TEQ ng/kg) 20000 U/S of M1 Dioxin concentration 10000 Netherthorpe 0 Renishaw (Rother)

Canklow

Jul-91 Jul-92 Jul-93 Jul-94 Jul-95 Jul-96 Jul-97

Mar-92 Mar-93 Mar-94 Mar-95 Mar-96 Mar-97

Nov-91 Nov-92 Nov-93 Nov-94 Nov-95 Nov-96 Nov-97 Time of measurement

Figure C.4: Graph of the dioxin concentrations in the River Doe Lea and River Rother between the sampling period of 1991-1998 [Produced with data from Scott Wilson (1998)]

Along with the clear spikes in dioxin concentrations, the NRA (1995) discussed how the visual quality of water dramatically reduced downstream of the pollution source. Notably, downstream of Coalite the water was brown due to the discharges and became foamy when disturbed. In order to treat the dioxin pollution upon its occurrence in 1991, nine management options were considered in depth to control the dioxin pollution in the river. These included:

o In situ „do nothing‟ approach

o Water injection dredging

o Capping

o Disposal to British Waterways landfill

o Disposal to commercial landfill

o Thermal treatment

o Detoxification

o Humber disposal

o Bioremediation

Some papers such as that of Huntley et al. (2001) suggested that a method of non- intervention was the BPEO for the dioxin remediation. However, Scott Wilson (1998), whilst discussing the relative merits of a method of non-intervention, suggested that river dredging and landfill was the BPEO for the polluted sections of river. The report concluded that dredging and landfill disposal offered the ‘most

- 116 - rapid progress, lowest overall risk, lowest cost solution and with acceptable risks’ (Scott Wilson, 1998).

A paper by British Waterways (1998) agreed with the BPEO suggestion of Scott Wilson, though questioned the feasibility of dredging the non-navigable sections of the river. From personal study, it is clear that accessibility to the river can be problematic due to excessive overgrowth of rural areas and extensive engineered channelisation of the river in the industrial lower reaches. British Waterways did conclude however, that landfilling options would provide the least risk to human health. Whilst raising concerns of the liability of British Waterways owning the landfill site and future concerns; it was concluded in agreement that dredging and landfill would be the BPEO for this case.

Modelling work undertaken by Scott Wilson found that the recovery time for the „do- nothing‟ approach was much longer for navigable sections of the waterway. The reduced velocity and advective fluxes of navigable sections would ensure remediation took decades and greatly increased the risk of a dioxin contaminated plume expanding over an even larger area of the SSYN (Scott Wilson, 1998). The report continued to conclude how bioremediation was unfeasible due to the ‘practical implementation of such a scheme to a problem of this magnitude’.

In 1998, the Environment Agency completed a follow up sampling investigation and found that dioxin levels had again built up in the BETP of the Coalite site. Whilst not contributing to the watercourse, the potential for another outbreak was increased as the higher concentrations of dioxins were again present. The EA concluded that there were still sources of dioxin production on site and included this into their management package (EA, 1998).

As the pollutant was advected downstream, the concentrations within the Doe Lea reduced to manageable levels. The problem was by no means solved as sediment deposition of dioxin pollutants in slow flowing waterways downstream now have the dioxins embedded within the river bed. The reduced levels were deemed to not to pose a significant risk to the aquatic environment. A reduction of 70% dioxin concentration was seen in the Doe Lea from 1992 to 1996 (EA, 1997). This resulted

- 117 - in the do-nothing recommendation being suggested by NRA (1995) but to continue further investigation and long term monitoring of sediment.

References:

th o Environment Agency, 1998. Dioxins on the Don update: 9 September 1998. Internal memo of the Environment Agency

o Huntley, D. Leeks, G. and Walling, D. 2001. Land-Ocean interaction: Measuring and modelling fluxes from river basins to coastal seas. IWA publishing: London

o Lake, I. Foxall, C. Lovett, A. Fernandes, A. Dowding, A. White, S. and Rose, M. 2005. Effects of river flooding on PCDD/F and PCB levels in cows' milk, soil, and grass. Environmental Science & Technology. 39(23), pp.9033-9038.

o NRA, 1995. River Doe Lea restoration study. Ove Arup & Partners: Leeds, UK.

o Scott Wilson Ltd, 1998. Contaminated sediments in the Sheffield and South Yorkshire Navigation (SSYN): Risk assessment of options. British Waterways, Gloucester, UK.

- 118 - Appendix D: Additional maps of land use in the catchment:

Figure D.1: Enlarged map of the combined landuse in the Doe Lea Catchment. The map is broken into the 50 sub-catchments to investigate runoff/infiltration/evapotranspiration contributions numbered by the sample locations.

- 119 - Figure D.2: Detailed plot of additional known land users and there distribution across the catchment. The maps have been divided up into agricultural, sewage treatment, industrial and mining land use.

- 120 - Sample Flow measurement X Coordinate Y Coordinate X Coordinate Y coordinate point location 3 446184.897 362170.270 Doe Lea Bridge 446098 369129 5 446667.828 362877.169 Palterton Springs 447306 367642 6 445977.182 363220.066 Tom Lane 443465 372216 7 445265.804 362785.395 Clowne Springs 448460 375340 8 445388.360 363030.507 Hawke Brook at M1 446328 374265 9 444301.542 362803.894 Netherthorpe 444255 374543 10 444946.695 362993.509 M1 Bridge 445068 373249 11 445399.465 364012.031 Doe Lea Source 445703 360998 12 444062.053 363785.475 Sample point 9 444111 362753 13 444101.000 364746.000 (OvergrownSample point and 12 444043 363809 14 445068.943 365040.127 (OvergrownHardwickinaccessible) Inn and 445786 363356 15 444045.715 365925.633 inaccessible)Spoil Heap 445402 373170 16 445025.152 365863.090 17 445700.000 366010.000 Sewage Treatment Works Discharges 17a 445848.142 366519.553 18 446714.128 366345.908 Location X Coordinate Y coordinate 19 446504.910 367389.293 20 446090.151 367096.266 Long Duckmanton 443680 371233 22 446134.050 367888.281 StaveleySTW STW 444310 376588 23 445953.001 367712.342 Clowne STW 448103 375115 24 444388.569 367395.087 Buttermilk Lane STW 445544 371993 25 445163.046 367851.126 Unknown STW 445568 371299 26 444001.668 368145.794 New Bolsover STW 446019 370095 27 445188.403 368343.445 Stockley STW 445979 367908 28 446142.613 369024.993 Astwith STW 444272 363997 29 443611.000 368950.000 31 445348.261 369594.620 32 443554.992 370633.632 33 443696.484 371527.372 34 445962.061 370516.059 35 445634.383 371495.523 36 445261.110 372377.459 37 443150.102 371960.964 38 443540.764 372044.385 39 443440.137 372312.324 40 443102.961 373283.948 41 445667.198 373232.139

42 443765.355 373820.472 42a 444378.783 373988.240 43 447627.007 372537.495 44 444449.510 374711.617 45 445914.759 374207.666 46 447620.369 375521.368 46a 447812.281 375860.051 47 448044.745 374338.703 48 448109.837 374981.510 49 447509.920 374741.032 50 444356.458 376196.863 51 444281.574 377101.157

Figure D.3: Coordinates of sample points, flow measurement locations and sewage treatment discharge points

- 121 - Site on Site on Doe Chainage Site on Chainage Chainage Hawke Lea (metres) Pools Brook (metres) (metres) Brook

Source 0m Source 0m Source 0m

3 1500m 29 120m 48 900m

5 2500m 33 2600m 49 1440m

6 3500m 38 3250m 45 2940m

Discharge to 11 4350m 39 3550m 4640m Doe Lea

17 6480m 42 5425m

Discharge to 17a 6925m 6040m Doe Lea

20 7700m

23 7960m

28 9760m

34 11335m

35 12235m

36 13040m

42a 15860m

44 16260m

50 17310m

Discharge to 18300m River Rother

Figure D.4: Chainages (distance downstream) of sample points in the three main water bodies of the catchment

- 122 -