Humber River Basin District
WFD Investigation
Mining Pollution: Catchment Characterisation Report (updated 20 August 2014)
Project details Project name Barney Beck catchment characterisation Contact Andrea Lancaster (or Hugh Potter) Contact team GWCL-Yorkshire Area Area Environment Manager Martin Christmas Water body summary information Surface Water Body Name Barney Beck (Old Gang Beck/Hard Level Gill) Surface Water Body ID GB104027069080 Surface Water Catchment Swale, Ure, Nidd & Upper Ouse (SUNO) Groundwater Body Name SUNO: Millstone Grit & Carboniferous Limestone Groundwater Body ID GB40402G701900 (Humber River Basin District) RBP Measure in WAP None (Good Status – but see below) RFF Database No Related catchments River Swale (4 downstream water bodies)
Water body classification Surface water body Status (2009) Status (2013) Elements failing classification Ecological Status Good Moderate Cu Biological Status Good High Specific Pollutants High Moderate Cu Chemical Status Not assessed Fail Cd, Pb, Ni Groundwater Body Status (2009) Predicted Status Reason for not classification achieving good status (failing elements) Disproportionate cost Chemical Status Overall Poor Good by 2027 Technically infeasible Surface water impacts Poor Good by 2027 Technically infeasible Drinking water protected Poor Good by 2027 Disproportionate cost area General chemical Poor Good by 2027 Technically infeasible assessment Upward pollutant trend Yes Comments No monitoring for metals was carried out for the 2009 classification.
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Summary of impacts from abandoned mines NoCAM result Impacted Score = 7 Rank (Oct 2013) England = 31st Yorks Humber RBD = 3rd SWMI At risk Elements: Cd, Pb, Ni, Cu
Mining Waste Directive MWD inventory URN Site name Mine type Reason Easting Northing 1227 Friarfold Rake Metalliferous Water pollution 396170 502281 1228 Barras End Mine Metalliferous Water pollution 398711 501038 Potential MWD inventory 1226 Old Gang Mill Metalliferous Water pollution 397535 500450
Summary of source apportionment study Item Details Comment Summary of impacts Significantly polluted by Cd, Pb, Zn from spoil and adit discharges. # water bodies Up to 3 Barney Beck contributes to impacted failure in River Swale Length of river 12 km of Barney Beck and up to impacted (km) 100 km of River Swale Metals failing current Zn = 3x At downstream point of study EQS Cd = 14x area (BB9). Failure at Pb = 15x catchment outlet (BB10) is Zn (3x), Cd (12x), Pb (11x) Metals failing Zn = 5x At downstream point of study bioavailable EQS Pb = 15x area (BB9). Failure at catchment outlet (BB10) is Zn (5x), Pb (17x) Is there an outbreak Not known risk? # of sources At least three adits and extensive mine spoil Metal loading (mean) – Zn = 682 (322 – 1128) Hard Level + Dam Drain + point sources (kg/yr) Cd = 5.2 (3 – 8.7) Spence Level Pb = 196 (42 – 569) Metal loading (mean) – Zn = 917 (190 – 3,679) At BB9 river (kg/yr) Cd = 7 (2 – 25) Pb = 914 (78 – 5,205) How many sources Need to deal with Hard Level and spoil heaps to improve towards need to be treated to EQS in Barney Beck. achieve EQS (good status) ? Length of river Unlikely to achieve EQS in Barney Beck but aim is to meet EQS improved by treatment in downstream River Swale (up to 100 km). (km)
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NWEBS benefit (£m Barney Beck water body = £2.18m over 40 years) River Swale (4 water bodies) = £30.4m (part to be allocated to Barney Beck). BCR > 1 for duRBMP Yes = 5.55 (2014) Potential contribution Not known. from others?
Recommendations Options Comment Source apportionment study Feasibility: 1. The main sources of Zn and Cd are: sources defined, move Hard Level (BB4): this is the most significant source to feasibility under all flow conditions but particularly low-medium flows (27-163% of Zn flux at BB9; 31-127% of Cd flux at BB9). Treatment of Hard Level (70% decrease in flux) should lead to compliance with the Zn and Cd EQS under lower flow conditions.
2. Pb arises from two main sources: Wastes upstream of Hard Level (Friarfold Rake area). Hard Level mine water (lower flows). Treatment of Hard Level (70% decrease in flux) will not significantly improve EQS compliance for Pb.
3. Share final report with the Coal Authority: Scoping study for 14/15 focussed on Hard Level, Spence Level and Dam Drain, as well as diffuse sources at Friarfold Rake and elsewhere. Yorkshire Dales National Park Authority is keen to help reduce further erosion of mining wastes.
National delivery team Priority Pass to Coal Authority decision High
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Catchment characterisation study
Pollution from abandoned metal mines adversely impacts both surface water quality and aqueous ecology with potential reduction in WFD status. The metal pollution derives mainly from minewater discharges out of drainage adits/levels, spoil tip run-off, and spoil tip erosion. Metal bearing river sediments are remobilised during high rainfall and high river flow events then transported downstream with potential spreading onto floodplains used for farming.
Barney Beck (8km long), located in the northern part of the Humber River Basin District (see Figure 1), is a tributary of the River Swale in the Yorkshire Dales National Park; with the confluence some 22km upstream of Richmond. Barney Beck catchment (17km2) is shown in Figure 2, with recent water quality monitoring points shown as yellow circles. Barney Beck drains a former lead mining area, where the minerals extracted included galena (PbS), sphalerite (ZnS) and barite (BaSO4).
Figure 1. Barney Beck location within the Humber River Basin District (in pink)
Barney Beck was identified with elevated metal concentrations (Pb, Cd, Zn) in the EA Yorkshire Metal Mines Study (2010) from a single sample at the confluence of Barney Beck with the River Swale. These results were subsequently confirmed by a sampling programme conducted by Hull University in 2010 and by the EA in 2011 for the MWD project. The previous water quality results are summarised in the table below, where the metals identified are consistent with the ores formerly mined in the catchment; cadmium being an impurity in the main lead and zinc mineral ores.
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Figure 2. Barney Beck catchment location map
Historic water quality The metal concentrations were compared to current 2013 annual average EQS values with exceedences high-lighted in pink in the table below. The EQS values for zinc, cadmium and copper are variable and depend on the hardness of the receiving waters. The mean hardness in the samples shown below was 81mg/L and in all the samples in this project the mean hardness was 51mg/L. These fall into the hardness band from 50-100mg/L and so the relevant EQS values are: 50g/L for zinc; 0.09g/L for cadmium; and 6g/L for copper.
Pb Zn Cd Ni Cu Flow Date Location NGR (g/L) (g/L) (g/L) (g/L) (g/L) (L/s) Barney Beck u/s Swale Feb-10 SE014992 74 150 1.1 1.2 2 400 confluence Jul-10 Hard Level Discharge NY971007 33 541 3 1 1 2 Spence Level Jul-10 NY972006 4 74 <1 <1 1 12 Discharge Victoria Level Jul-10 NY966006 <1 9 <1 <1 1 0.1 Discharge Barney Beck u/s Hard Feb-11 NY969008 323 152 0.9 1.7 2 - Force Feb-11 Hard Level Discharge NY971007 96 551 4.5 2.7 2 25 Adit Discharge at dam Feb-11 NY972006 16 95 0.4 <1 <1 3 u/s Spence Level Spence Level Feb-11 NY972006 22 97 0.5 <1 <1 7 Discharge Barney Beck d/s spoil Feb-11 NY977004 209 234 1.8 1.9 2 - tips EQS Annual Average (g/L) 7.2 50 0.09 20 6 -
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The above water quality monitoring identified significant metal pollutants in Barney Beck that were not originally identified in the first RBMP of 2009, because metals were not included in the routine analysis suite.
Mining Waste Directive
The following sites in the Barney Beck catchment are on the MWD Article 20 Inventory.
URN Site Name Mine Type Reason Easting Northing MWD Inventory 1227 Friarfold Rake Metalliferous Water pollution 395600 502050 1228 Barras End Mine Metalliferous Water pollution 398711 501038 Potential MWD Inventory 1226 Old Gang Mill Metalliferous Water pollution 397535 500450
Mining History Summary
Barney Beck drains an area of former lead mining, which was carried out extensively throughout the catchment from about 1700 to 1900, most actively in the 1800s, followed by some reworking of spoil tips until the 1990s. The orefield comprises lead-zinc mineral deposits within Carboniferous Limestone and Millstone Grit host rocks. Galena (PbS) is the most common mineral with associated ‘gangue’ minerals including sphalerite (ZnS), chalcopyrite (CuFeS2), barite (BaSO4), fluorite (CaF2) and calcite (CaCO3). These minerals occur mostly in vertical veins along fault planes, as shown on Figure 3 and Figure 4 below.
Early mine workings were open cuts, with shafts used to work deeper in later years, but exploitation was initially limited by the water table. The scouring technique of hushing was used until about 1850 to expose mineral veins at the surface by the erosive power of water released from temporary dams. Horizontal drainage levels (adits) were driven from the valley bottoms to enable deeper working and for easier removal of minerals from the mines. The ore was crushed and dressed at the surface close to the mines to further concentrate the metal before smelting at sites close to the mines. Water power was used at ore dressing floors and smelt mills and so these sites and their spoil tips are often located next to rivers.
The main mining features in Barney Beck catchment are as follows.
Lead Mines NGR Adits/Levels Hushes Spoil Tips Smelters Friarfold Brandy Bottle Friarfold NY 9554 0202 Merryfield Forefield NY 9648 0240 Surrender NY 9728 0249 Moulds Top NY 9850 0230 Moulds Side Wetshaw NY 9804 0208 Merryfield Reynoldson North Rake NY 9544 0138 Old Rake Roger Old Rake Hard Knots Old Gang Old Gang Old Gang NY 9713 0066 Spence Herring Rake Tailings Dam Smith’s Hard Level Victoria Barras High Kay Surrender Barras End NY 9888 0092 Barras Low Moulds Low
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Figure 3. Aerial photograph showing mining scars along mineralised faults
Figure 4. BGS map detail (1985) showing levels and mineral veins
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Historical Ecological Data
Prior to the current project ecological sampling has generally been sporadic at best and Barney Beck has not been sampled since the early 1990s. Prior to the project ecological sampling was primarily undertaken as part of the ‘headline indicator’ programme which formed part of the General Quality Assessment (GQA) classification. However as the GQA network was reduced Barney Beck was removed from the programme. From 2013 routine sampling has been reinstated under the new Ecological Status Indicator (ESI) programme and will form the basis of WFD classification from 2014 onwards.
A separate report on ecological monitoring carried out by the Environment Agency in 2012/13 to investigate metal impacts is available (Environment Agency, 2014).
Designations
The Barney Beck catchment is entirely located in the Yorkshire Dales National Park. Almost all of the catchment forms part of the Arkengarthdale, Gunnerside and Reeth Moors SSSI, designated for blanket bog, heather moorland and for their breeding bird populations; and is also part of the North Pennine Moors SPA and SAC. A small area of woodland (12ha) alongside Barney Beck at Birk Park Wood near to the Swale confluence is designated as Ancient and Semi-Natural Woodland.
There are 2 Scheduled Ancient Monuments in the catchment, these are: Old Gang Smelt Mill complex including, buildings, flues, chimneys and spoil tips Surrender smelt Mill complex including, buildings, flues, chimneys and spoil tips
There are no licensed abstractions in the catchment.
Designated sites are shown on Figure 5 below, where the coincident SSSI, SPA and SAC are shown by light green shading, ancient woodland is dark green and the Scheduled Ancient Monuments are shown as yellow triangles.
YDNPA report on mining heritage at Barney Beck
The Yorkshire Dales National Park Authority (YDNPA) and the Environment Agency have entered into an agreement for the YDNPA to produce reports on the mining heritage in 3 catchment areas within the National Park: Gunnerside Gill and Barney Beck in Swaledale; and Hebden Gill in Wharfedale. This opportunity for collaboration has identified an important synergy between the aims of the two organisations. YDNPA are concerned to preserve the nationally (sometimes internationally) important mining features such as shafts, levels, smelters, buildings, water management structures (dams, leats, sluices and water wheels), ore dressing floors, slag heaps and spoil tips. Erosion of spoil tips represents a significant source of metal pollution in surface water and so erosion reduction is a clear common goal that will both improve surface water quality and help to protect the mining heritage.
A report on Barney Beck is available (Yorkshire Dales National Park Authority, 2013) which included a survey of the mining remains of both scheduled and undesignated features, with focus on areas of active erosion and suggestions for potential mitigation measures. This is summarised briefly below.
Water power was extensively used for ore dressing (crushing and sorting) to concentrate the ore for smelting, this close association resulted in many spoil tips located adjacent to watercourses with ore particles remaining in the finer spoil. Rare metallophyte plant communities such as calaminarian grassland grow on metal-rich substrates such as mining
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spoil, but these are slow growing and vulnerable to disturbance and climate change pressures. Some spoil tips were re-worked for barium from the 1950s, but have not been re- colonised by vegetation, and so are susceptible to erosion.
Figure 5. Designated sites at Barney Beck
The catchment is open access land and regularly used for recreation including walking, mountain biking, motocross and for grouse shooting. These activities all contribute to spoil tip disturbance and erosion, along with livestock grazing and, in particular, rabbit burrowing.
The mining features inspected were divided into 16 sites as follows. Friarfold Vein and extensive bare spoil (run-off and active erosion identified). Brandy Bottle Mines and spoil tip (some erosion identified). Surrender Mines (some run-off and erosion identified). Moulds Side Mines (some run-off and erosion identified). Wetshaw Bottom Mines (vegetated). Old Rake Vein (some run-off and erosion identified). Roger Level and Victoria Level and spoil tips (no action required). Herring Rake Vein (mostly vegetated). Swaledale Reprocessing Works and Tailings Dam (some run-off identified). Old Gang Complex, Hard Level and spoil tip (significant active erosion identified). South of Old Gang Smelt Mill (vegetated, no action required). Smith’s Smelt Mill (no action required). Barras End Mines, Levels and Moulds Smelt Mill (vegetated, no action required).
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Surrender Smelt Mill (significant active erosion identified). Healaugh Brow Mines (no action required).
Potential spoil tip stabilisation and erosion mitigation measures identified were as follows. Spoil tip reinforcement using structures: such as stone walls or gabion baskets. Water management: diverting, piping, or culverting watercourses away from spoil tips. Re-vegetation of spoil tips to reduce erosion, preceded by botanical seeding studies. Peat grip blocking under the Yorkshire Peat Partnership moorland restoration project. Tree planting in the tributary valleys to regulate high flows. Control of recreation activity, especially wheel-based pursuits (e.g. Scott Trial). Control of re-use of spoil for access track maintenance. Control of livestock grazing and rabbit population reduction.
Photographs
Barney Beck looking downstream to Old Gang Smelt Mill and spoil tips
Spence Level Portal
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Hard Level Portal
Geology
The solid geology of the Barney Beck catchment (17km2) is shown on Figure 6 below, comprising mostly Millstone Grit (green) on the higher ground in the north, overlying Carboniferous Limestone (blue) exposed in the valley bottom in the south. Millstone Grit covers 65% of the catchment (11km2) while Carboniferous Limestone covers 35% (6km2) and includes most of the sampling locations for this project.
Figure 6. Solid geology of the Barney Beck catchment
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A number of W-E and NW-SE trending faults cross the catchment; many of these are mineralised, and are likely to have a significant effect on surface water quality and groundwater flow conditions. The extensive mining voids in the upper part of the catchment have permanently altered the hydrogeological conditions, creating fast pathways for rainwater infiltration to pass through the mined areas and enter the river.
The drift geology of the Barney Beck catchment (17km2) is shown on Figure 7 below, comprising Peat (in brown) on the high ground in the north and Glacial Till (in light blue) in the south and in the valley bottom. Peat covers 35% of the catchment (6km2), resting mostly upon Millstone Grit, and is located upstream of the sampling locations. Glacial Till covers 30% (5km2), sitting upon Carboniferous Limestone, with a further 35% (6km2) of the catchment where superficial deposits are absent.
Figure 7. Drift geology of the Barney Beck catchment
Monitoring programme This study is designed to characterise the Barney Beck catchment by investigating the impact of former metal mining on river water quality and aqueous ecology. Mining records were used to identify potential monitoring sites, followed by a catchment visit to identify safe and practical locations for water quality sampling, ecological sampling and flow measurement. Sources of elevated metal concentrations will be identified to help the design of potential mitigation and remediation measures.
The sampling programme began in March 2012 and was planned for 12 monitoring visits at monthly intervals comprising water quality sampling at 9 locations from BB1 (upstream) to BB9 (downstream) with simultaneous flow measurement at 6 locations (BB1, BB3, BB4,
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BB6, BB7, BB9). BB1, BB3 and BB9 are river monitoring points, BB1 is the upstream location, BB3 is 1km downstream and BB9 is 2.4km downstream of BB1. Adits are monitored at Hard Level (BB4), Dam Drain (BB6) and Spence Level (BB7). BB2, BB5 and BB8 are small tributaries of Barney Beck. Victoria Level was not monitored because of very low intermittent flows. The water quality and flow measurements were used to calculate metal loading to identify the contribution from each inflow into Barney Beck.
The water quality and flow monitoring points are shown on Figure 8 below and also listed from upstream (BB1) to downstream (BB10) in the table below.
Site Distance URN Location Easting Northing Ref (km) BB1 49905135 Barney Beck u/s Old Rake 396265 501519 0
Old Rake Tributary at Barney BB2 49905136 396402 501315 0.3 Beck
BB3 49905137 Barney Beck u/s Hard Level 396896 500846 1.0
BB4 49905138 Hard Level Minewater Adit 397127 500664 1.3
Surrender Moss Tributary at BB5 49905139 397142 500640 1.4 Barney Beck
BB6 49905140 Dam Drain - Reeth High Moor 397183 500636 1.4
BB7 49905141 Spence Level Minewater Adit 397225 500623 1.5
Healaugh Side Tributary at BB8 49905142 397391 500544 1.6 Barney Beck Barney Beck d/s Healaugh BB9 49905143 398048 500223 2.4 Side Tributary
BB10 49905127 Barney Beck at Helaugh 401365 498888 6.4
BB10 is located 2km further downstream at the confluence of Barney Beck with the River Swale, and is shown on Figure 2, Figure 6 and Figure 7 as the eastern-most yellow circle within the catchment.
Bleaberry Gill, a tributary of Barney Beck, was not sampled as part of this project, because although recent monitoring data showed some metal pollution, this was insignificant compared to the metal concentrations in Barney Beck. There are mining features in the catchment of Bleaberry Gill, including a MWD inventory site at Barras End Mine.
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Figure 8. Barney Beck sampling points
The water quality analysis suites were selected as follows.
Metals Analysis Field Site Ref Laboratory Determinands (Dissolved Suite Determinands and Total) BB1, BB2 Dissolved Organic Carbon BB3, BB5 Al, B, METSTR Suspended Solids, BB8, BB9 pH, EC, DO, Ba, Ca, for surface Hardness as CaCO , BB10 Temperature 3 Cd, Cr, waters pH, Alkalinity @ pH4.5, WSB1 Cu, Fe, Cl, NO , NH , SiO , SO WSB2 2 3 2 4 K, Li, Mg, Mn, EC, DO%, BB4 Na, Ni, METPR pH, EC, DO, Hardness as CaCO , BB6 3 Pb, Sr, for adits Temperature pH, Alkalinity @ pH4.5, BB7 Zn Cl, NO2, NH3, SiO2, SO4
Ecological monitoring was undertaken downstream of the main mining areas on Barney Beck downstream of Old Gang Smelt Mill (BB9) and at Healaugh, near to the Swale confluence (BB10), to assess whether the historical mining activity has adversely affected the aqueous ecology.
Additional ecological monitoring was also carried out in a neighbouring control catchment located to the west of Barney Beck, shown in Figure 9 below. West Stonesdale Beck (GB104027069150) is another north bank tributary of the River Swale, with its confluence 17km upstream of the confluence between Barney Beck and the River Swale. West Stonesdale Beck has similar geology and geomorphology to Barney Beck. Lead mining was not carried out extensively in the West Stonesdale Beck catchment, but small coal mines,
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such as Tan Hill Colliery (operated from about 1880 to 1940) are located at the very top of the catchment.
Ecological sampling has been conducted on 6 occasions to date: in Spring, Summer and Autumn of 2012 and 2013. The results are presented in a separate report (Environment Agency, 2014).
Figure 9. West Stonesdale Beck catchment location
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The monitoring visits were conducted with simultaneous water quality sampling (Q), spot flow measurements (F), and ecological sampling (E) as follows.
Date BB1 BB2 BB3 BB4 BB5 BB6 22/03/12 Q+F Q Q+F Q+F - Q+F 25/04/12 Q+F Q Q+F Q+F Q Q+F 15/05/12 Q+F Q Q+F Q+F Q Q+F 21/06/12 Q Q Q+F Q+F Q Q+F 17/07/12 Q+F Q Q+F Q+F Q Q+F 13/08/12 Q Q Q Q - Q 13/09/12 Q+F Q Q+F Q+F Q Q+F 16/10/12 Q+F Q Q+F Q+F Q Q+F 21/11/12 Q+F Q Q+F Q+F Q Q+F 14/12/12 Q Q Q Q+F Q Q 28/01/13 Q Q Q Q Q Q 28/02/13 Q+F Q Q+F Q+F Q Q+F 19/03/13 Q+F Q Q+F Q+F Q Q+F 28/05/13 ------Q = 13 Q = 13 Q = 13 Q = 13 Sub-totals Q = 13 Q = 11 F = 9 F = 10 F = 11 F = 10 Date BB7 BB8 BB9 BB10 WSB1 WSB2
22/03/12 Q+F Q Q+F - - - 25/04/12 Q+F Q Q+F - - - 08/05/12 - - E E E E 15/05/12 Q+F Q Q+F - - - 21/06/12 Q+F Q Q+F - - - 17/07/12 Q+F Q Q+F - - - 31/07/12 - - E Q+E Q+E Q+E 13/08/12 Q Q Q - - - 13/09/12 Q+F Q Q+F - - - 16/10/12 Q+F Q Q - - - 23/10/12 - - E Q+E Q+E Q+E 21/11/12 Q+F Q Q+F - - - 14/12/12 Q Q Q - - - 28/01/13 Q Q Q - - - 28/02/13 Q+F Q Q+F - - - 19/03/13 Q+F Q Q+F - - - 28/05/13 - - Q+E Q+E Q+E Q+E 12/08/13 - - Q+E Q+E Q+E Q+E 14/11/13 - - Q+E Q+E Q+E Q+E Q = 14 Q = 13 Q = 3 Q = 3 Q = 3 Sub-totals Q = 13 F = 9 F = 10 E = 6 E = 6 E = 6 E = 6 TOTALS Q = 129, F = 59, E = 24
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Flow Measurements The 6 flow monitoring sites comprise 3 locations on Barney Beck (BB1, BB3, BB9) and 3 inflows from mine drainage adits (BB4, BB6, BB7). The spot flow gauging results after 11 rounds of monitoring using the velocity/area method at 6 locations are shown in the table below, with the river locations high-lighted in grey. As expected, the flows in Barney Beck increase steadily downstream from BB1 on the left of the table to BB9 on the right. This shows that significant quantities of flow are not lost into the underlying Carboniferous Limestone bedrock, on which the monitoring points are located.
Catterick Bridge Grinton Spot flow measurements at Barney Beck (L/s) Flow Gauge F2306 Level Date Daily Gauge BB1 BB3 BB4 BB6 BB7 BB9 Percent mean L2309 (river) (river) (adit) (adit) (adit) (river) ile Flow (L/s) (%ile) 22/03/12 1 3 19 3 3 48 1830 Q87 Q90 25/04/12 9 24 31 3 4 138 7550 Q44 Q42 15/05/12 10 26 47 3 11 134 8850 Q38 Q40 21/06/12 - 12 39 4 4 127 6530 Q50 Q54 17/07/12 1 13 35 4 5 86 5940 Q53 Q49 13/08/12 ------2600 Q79 Q88 13/09/12 35 54 36 4 4 129 5960 Q53 Q31 16/10/12 372 546 48 24 9 - 38,800 Q07 Q06 21/11/12 218 393 62 13 7 864 24,000 Q13 Q15 14/12/12 - 14 37 2 5 - 32,600 Q09 Q09 28/02/13 14 23 30 2 4 82 5130 Q58 Q62 19/03/13 19 32 33 2 5 123 12,300 Q28 Q32 Mean 76 104 38 6 5 192 - - -
The nearest flow gauging station with continuous measurement is located on the River Swale at Catterick Bridge (F2306), some 30km downstream and east of Barney Beck. Estimates of the percentile flow values for the spot flow measurements at Barney Beck can be obtained from the long term flow duration curve (or table) at F2306. Daily mean flows at Catterick Bridge were obtained for the dates of the Barney Beck monitoring visits and the percentile values of these flows were determined from the flow duration curve shown in Figure 10 below. These range from Q07 to Q87, where the lowest flow at Catterick Bridge (Q87) is exceeded 87% of the time, and the highest flow (Q07) is exceeded only 7% of the time.
The nearest level gauging station to Barney Beck on the River Swale at Grinton Bridge (L2309) is located 4km downstream of the confluence between the Swale and Barney Beck. Daily mean levels at Grinton Bridge were obtained for the dates of the Barney Beck monitoring visits and the percentile values of these flows were determined from the level duration curve. The table above shows there is good correlation between the long-term flow and level duration curves at Grinton and Catterick, except where high-lighted in pink.
The flow conditions at Catterick Bridge give a good indication of flow conditions at Barney Beck, but localised rainfall events at either location could make this correlation less useful. Grinton Bridge at 4km is much closer to Barney Beck than the flow gauging station at Catterick Bridge at 30km, so the Grinton percentile values are more applicable to the Barney Beck catchment.
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Figure 10. Long-term flow duration curve for Catterick Bridge (F2306)
When the spot measured flows at the most downstream monitoring point on Barney Beck (BB9) are ranked in order from low to high flow rate, they correlate fairly well with the flows at Catterick Bridge (F2306) and the levels at Grinton Bridge (L2309), as shown in the table below. The main exceptions are high-lighted in pink, in particular, where there is also the least good correlation between the percentile flows at Catterick and the percentile levels at Grinton.
Spot flow at Daily mean flow Percentile flow Percentile Date 3 3 BB9 (m /s) at F2306 (m /s) at F2306 Level at L2309 22/03/2012 48 1830 Q87 Q90 13/08/2012 - 2600 Q79 Q88 28/02/2013 82 5130 Q58 Q62 17/07/2012 86 5940 Q53 Q49 19/03/2013 123 12,300 Q28 Q32 21/06/2012 127 6530 Q50 Q54 13/09/2012 129 5960 Q53 Q31 15/05/2012 134 8850 Q38 Q40 25/04/2012 138 7550 Q44 Q42 21/11/2012 864 24,000 Q13 Q15 14/12/2012 - 32,600 Q09 Q09 16/10/2012 - 38,800 Q07 Q06
Low Flows Enterprise Software could also be used to estimate flows in a catchment, but this tool only provides long-term monthly or annual averages and doesn’t give information for specific dates, which would be needed for this study.
Spot flow gauging using the velocity-area method is generally considered to only be accurate under laminar flow conditions, but flow in natural rivers with irregular shape and granular substrate is typically turbulent. A graphical method using a time series of measured concentrations of a known spike of salt (NaCl) added to the river could be more accurate.
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Flow Balances A schematic conceptual model of the Barney Beck catchment and the monitoring locations is shown in Figure 11 below.
Figure 11. Conceptual model of catchment flows
Barney Beck BB1 Barney Beck upstream (METSTR) sampling ^ Flow and quality Level House Bridge unless noted Bridge u/s Hard Level Force BB2 Old Rake trib (METSTR) Water quality only BB3 Upstream of Hard Level (Barney Beck) (METSTR)
BB4 Hard Level (METPR)
BB5 Surrender Moss trib (METSTR) Water quality only
BB6 Dam drain (METPR)
BB7 Spence Level (METPR)
BB8 Healaugh Side trib (METSTR) Water quality only Spoil heap adjacent to river
BB9 Barney Beck downstream (METSTR)
BB10 Barney Beck at Healaugh (4km downstream at Swale confluence)
River flow measurement is subject to uncertainty, however carefully undertaken, whether by manual spot gauging or at continuous flow gauging stations and this will also vary between low and high flow conditions. Therefore, significant discrepancies in the flow correlations may be explained by unknown inputs, but may also be due to measurement errors.
Flow balance calculations from the conceptual model can be used as a check on the accuracy of the spot flow gauging measurements, as follows:
BB3 = BB1 + BB2 (not measured) BB9 = BB3 + BB4 + BB6 + BB7 + BB5 (not measured) + un-named tributaries (not measured)
The calculations and correlations assume there are no other flow inputs into the system that have not been accounted for, either from point sources such as small tributaries and unknown adits or via diffuse baseflow (including baseflow via spoil). However, at Barney Beck at least 7 tributaries are easily identified that have not been measured for flow (see Figure 11 above).
In the tables below, correlation within 10% is rated as good and within 20% is rated as OK, while correlation errors of 20% or more are rated as poor.
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BB3+BB4+ Date BB3 BB4 BB6 BB7 BB9 % Error Correlation BB6+BB7 22/03/12 3 19 3 3 28 48 58% Poor 25/04/12 24 31 3 4 62 138 45% Poor 15/05/12 26 47 3 11 87 134 65% Poor 21/06/12 12 39 4 4 59 127 46% Poor 17/07/12 13 35 4 5 57 86 66% Poor 13/08/12 ------13/09/12 54 36 4 4 98 129 76% Poor 16/10/12 546 48 24 9 627 - - - 21/11/12 393 62 13 7 475 864 55% Poor 14/12/12 14 37 2 5 58 - - - 28/02/13 23 30 2 4 59 82 72% Poor 19/03/13 32 33 2 5 72 123 59% Poor Mean flow 104 38 6 5 153 192 80% Poor (L/s)
It is not surprising that this flow balance shows a consistently poor correlation because at least 7 un-gauged tributaries of Barney Beck are identified between BB3 and BB9.
Water quality results Water quality results for Barney Beck and the control catchment of West Stonesdale Beck (high-lighted in blue) are summarised below for 117 samples from 13 sampling rounds at 9 locations. The analysis suites contained 17 metals. The concentrations of Ni, Al, Cr, Li, B, Ba, Sr, Na, Ca, K, Mg were not significant and Cu, Mn and Fe showed very minor EQS exceedences. The table below shows dissolved and total concentrations of Pb, Zn and Cd, along with pH and flow. The tables show the minimum, mean and maximum concentrations, with the mean values high-lighted in bold. The monitoring points are listed from upstream (BB1, WSB1) to downstream (BB10, WSB2).
The concentrations were compared to current 2013 EQS values with exceedences high- lighted in increasing saturations of pink. Strictly, metal EQS values should be compared to either total or dissolved concentrations, but these were broadly similar for all sample results in this project, so both total and dissolved concentrations have been compared in the tables.
The current 2013 EQS values for Zn and Cd depend on the hardness of the receiving waters. The mean hardness of the upstream river samples (BB1, BB2, BB3, BB5) fell into the hardness band from 0-50mg/L and so the relevant EQS values are 8g/L for Zn and 0.08g/L for Cd. The mean hardness of the remaining river samples fell into the hardness band from 50-100mg/L and so the relevant EQS values are 50g/L for Zn and 0.09g/L for Cd.
Concentrations of Pb, Zn and Cd were very elevated in all samples within this project, with 100% of Pb, Zn and Cd results above EQS values.
See the next section for discussion of compliance with the new bioavailable EQS for Pb and Zn.
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Site Pb Pb Zn Zn Cd Cd Flow Monitoring Point Stats pH Ref Diss Total Diss Total Diss Total (L/s) Min 214 234 126 133 0.7 0.8 5.2 1 Barney Beck u/s Old BB1 Mean 471 494 203 204 1.1 1.1 5.6 76 Rake Max 729 758 283 280 1.6 1.5 6.7 372 Min 25 39 69 65 0.4 0.4 6.7 - Old Rake Tributary BB2 Mean 57 71 86 88 0.5 0.5 7.3 - at Barney Beck Max 107 118 114 123 0.7 0.7 7.7 - Min 70 92 103 107 0.7 0.7 6.1 3 Barney Beck u/s BB3 Mean 216 247 135 145 0.8 0.8 7.2 104 Hard Level Max 542 577 197 222 1.2 1.2 7.8 546 Min 47 52 408 436 3.2 3.4 6.7 19 Hard Level BB4 Mean 123 135 527 538 4.3 4.4 7.7 38 Minewater Adit Max 247 272 594 611 4.8 5.0 8.1 62 Surrender Moss Min 9 14 97 104 0.2 0.2 7.6 - BB5 Tributary at Barney Mean 51 67 164 179 0.3 0.4 7.8 - Beck Max 152 208 268 322 0.6 0.7 7.9 - Min 12 18 90 93 0.4 0.4 7.2 2 Dam Drain - Reeth BB6 Mean 79 92 133 126 0.6 0.6 7.6 6 High Moor Max 256 291 269 201 1.0 1.0 7.8 24 Min 26 32 81 84 0.5 0.5 7.7 3 Spence Level BB7 Mean 60 71 104 110 0.6 0.6 7.8 5 Minewater Adit Max 195 214 196 196 1.0 1.0 8.0 11 Healaugh Side Min 3 9 16 19 0.2 0.2 7.6 - BB8 Tributary at Barney Mean 21 55 20 33 0.2 0.3 7.9 - Beck Max 81 217 31 65 0.3 0.6 8.1 - Barney Beck d/s Min 51 57 124 124 0.9 1.0 7.4 48 BB9 Healaugh Side Mean 110 131 161 170 1.3 1.4 7.9 192 Tributary Max 309 346 217 223 1.8 1.9 8.3 864 Min 32 39 97 101 0.8 0.9 6.9 - Barney Beck at BB10 Mean 77 88 127 133 1.1 1.1 7.9 - Helaugh Max 125 138 160 163 1.2 1.3 8.3 - West Stonesdale Min <2 <2 <5 <5 <0.1 <0.1 7.2 - WSB Beck at Stonesdale Mean <2 <2 4 2 <0.1 <0.1 7.5 - 1 Bridge Max <2 <2 6 5 <0.1 <0.1 7.7 - West Stonesdale Min <2 <2 6 6 <0.1 <0.1 6.6 - WSB Beck u/s Currack Mean <2 <2 8 6 <0.1 <0.1 7.7 - 2 Force Max <2 <2 9 7 <0.1 <0.1 8.2 - EQS (AA) at BB1, BB2, BB3, BB5 8 0.08 7.2 6-9 - EQS (Annual Average) elsewhere 50 0.09 Diss = dissolved, all units are in g/L, except where indicated
The mean metal concentrations in Barney Beck upstream of BB1 exceed the current 2013 EQS values for Pb (65x), Zn (25x),and Cd (14x) because of inputs from the mining areas located upstream of the study area at the extensive hushes of Friarfold Rake and Forefield Rake. There are no significant minewater discharges identified upstream of the study area from point sources such as mine drainage adits/levels, so the metals are likely to arise from erosion of the large areas of exposed mining spoil and mineral veins. Further investigation may identify particular locations where rainfall run-off could be separated from this spoil to prevent further erosion. The mean metal concentrations leaving the catchment at BB10 also significantly exceed the relevant EQS values for Pb (11x), Zn (3x) and Cd (12x) despite additional dilution from less impacted tributaries, such as Bleaberry Gill.
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Site Mean metal Pb EQS Zn EQS Cd EQS Ref concentration (g/L) Exceeded Exceeded Exceeded BB1 Entering study area 65x 25x 14x BB9 Leaving study area 15x 3x 14x BB10 Leaving catchment 11x 3x 12x
The maximum recorded metal concentrations significantly exceed the relevant EQS values for Pb (101x at BB1), Zn (35x at BB1 and 12x at BB4) and Cd (53x at BB4), as indicated in darker shades of pink in the above table. The highest concentrations of Pb are those arriving from upstream of the study areas (BB1) and from Hard Level (BB4), which also contained the highest concentrations of Zn and Cd.
Site Maximum metal Pb EQS Zn EQS Cd EQS Ref concentration (g/L) Exceeded Exceeded Exceeded BB1 Entering study area 101x 35x 20x BB4 Hard Level 34x 12x 53x BB6 Dam Drain 36x 5x 11x BB7 Spence Level 27x 4x 11x
Parameter values in the adit discharges are summarised as follows.
Site Monitoring Flow Pb Zn Cd Cu Fe SO Stats pH 4 Ref Point (L/s) Diss Diss Diss Diss Diss mg/L Min 19 6.7 47 408 3.2 1.1 <30 13 BB4 Hard Level Mean 38 7.7 123 527 4.3 2.3 100 18 Max 62 8.1 247 594 4.8 3.4 243 26 Min 2 7.2 12 90 0.4 <1 <30 6 Dam Drain - BB6 Mean 6 7.6 79 133 0.6 0.7 174 11 Reeth High Moor Max 24 7.8 256 269 1.0 2.1 647 17 Min 3 7.7 26 81 0.5 <1 35 8 BB7 Spence Level Mean 5 7.8 60 104 0.6 0.5 122 13 Max 11 8.0 195 196 1.0 1.9 451 19 Diss = dissolved, all units are in g/L, except where indicated
Metal bioavailability assessment Assessment of water quality using current (2013) hardness-based EQS values for metals may be over- or under-protective of freshwater aquatic life, and new EQS based on bioavailability are being developed. The bioavailable concentration of Cu, Zn, Mn and Pb can be estimated from the concentrations of dissolved metal, dissolved organic carbon (DOC), Ca and pH; the standard for Ni is in development. The bioavailable metal is compared with Predicted No Effect Concentrations (PNEC) for Cu (1g/L), Zn (10.9g/L),Mn (123g/L) and Pb (1.2g/L) to calculate a Risk Characterisation Ratio (RCR) for each water quality sample. If the RCR is >1 the sample fails the bioavailable EQS A summary of the results is shown below (there were no failures for Cu or Mn).
The Metal Bioavailability Assessment Tool (MBAT) was used to calculate sample-specific bioavailable concentrations of these metals. These were compared with new generic EQS values that have been developed as Predicted No Effect Concentrations (PNEC) as follows: Cu (1g/L), Zn (10.9g/L), Mn (123g/L), Ni (4g/L), and Pb (1.2g/L). A Risk Characterisation Ratio (RCR) is also calculated for each sample, which fails the bioavailable PNEC if the RCR is greater than 1. A summary is shown below at the river sites that include DOC data.
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Number of EQS and Bioavailable PNEC Site Monitoring No. of Failures Ref Point Results Pb Pb Zn Zn Diss Bio Diss Bio Barney Beck u/s BB1 13 13 13 13 13 Old Rake Old Rake BB2 Tributary at 13 13 13 13 13 Barney Beck Barney Beck u/s BB3 13 13 13 13 13 Hard Level Surrender Moss BB5 Tributary at 11 11 11 11 11 Barney Beck Healaugh Side BB8 Tributary at 13 9 13 0 0 Barney Beck Barney Beck d/s BB9 Healaugh Side 14 14 14 14 14 Tributary Barney Beck at BB10 3 3 3 3 3 Helaugh Totals 90 86 90 67 67 Diss = dissolved, Bio = bioavailable.
The bioavailability assessment did not make any difference to the interpretation of the Pb and Zn results, where all samples that failed the current 2013 EQS also failed the generic bioavailable PNEC values. Pb failed throughout the catchment and Zn failed at all monitoring sites except the Healaugh Side tributary of Barney Beck (BB8).
The bioavailable concentrations of Pb, Zn, Cu, Mn and Ni in all sample results at the river monitoring sites were calculated using the MBAT Excel spreadsheet. All Cu, Mn and Ni bioavailable concentrations were below the relevant PNEC values and so are not shown here, but the Pb and Zn results are shown in the table below with EQS failures, bioavailable PNEC failures, and RTC >1 high-lighted in pink.
Site Monitoring Pb Diss Pb PNEC Pb Zn Diss Zn PNEC Zn Date Ref Point Measured Estimated RCR Measured Estimated RCR Mean 471 19 25 203 41 5 22/03/12 518 11 47 283 35 8 25/04/12 529 24 22 207 52 4 15/05/12 512 19 26 190 41 5 21/06/12 539 18 30 217 39 6 17/07/12 729 24 31 245 45 5 Barney 13/08/12 719 21 35 276 45 6 BB1 Beck u/s 13/09/12 684 37 18 209 77 3 Old Rake 16/10/12 335 25 13 126 56 2 21/11/12 334 23 14 150 50 3 14/12/12 387 13 30 181 29 6 28/01/13 214 10 21 141 23 6 28/02/13 356 12 29 218 27 8 19/03/13 270 5 52 200 14 15 Diss = dissolved, all units are in g/L
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Site Monitoring Pb Diss Pb PNEC Pb Zn Diss Zn PNEC Zn Date Ref Point Measured Estimated RCR Measured Estimated RCR Mean 57 12 5 86 42 2 22/03/12 26 5 5 75 23 3 25/04/12 49 10 5 82 38 2 15/05/12 53 10 5 70 38 2 21/06/12 63 12 5 75 42 2 Old Rake 17/07/12 75 14 5 79 48 2 Tributary at 13/08/12 80 14 6 86 51 2 BB2 Barney 13/09/12 107 26 4 107 87 1 Beck 16/10/12 95 21 5 100 65 2 21/11/12 74 14 5 114 49 2 14/12/12 36 7 5 69 28 2 28/01/13 37 8 5 76 28 3 28/02/13 25 5 5 77 23 3 19/03/13 29 7 4 102 27 4 Mean 216 13 17 135 44 3 22/03/12 70 4 19 103 20 5 25/04/12 261 13 21 156 46 3 15/05/12 222 12 19 134 44 3 21/06/12 126 9 14 121 36 3 17/07/12 181 10 18 121 39 3 Barney 13/08/12 179 11 17 122 40 3 BB3 Beck u/s 13/09/12 542 30 18 197 96 2 Hard Level 16/10/12 359 22 16 133 58 2 21/11/12 293 21 14 135 63 2 14/12/12 123 7 17 124 29 4 28/01/13 161 9 17 124 30 4 28/02/13 151 7 21 131 29 5 19/03/13 145 8 19 153 30 5 Mean 51 9 6 164 36 5 25/04/12 26 6 4 151 26 6 15/05/12 24 6 4 112 26 4 21/06/12 16 5 3 101 23 4 Surrender 17/07/12 33 6 5 101 29 4 Moss 13/09/12 152 23 7 256 88 3 BB5 Tributary at 16/10/12 139 18 8 268 69 4 Barney Beck 21/11/12 88 14 6 250 52 5 14/12/12 15 4 4 97 20 5 28/01/13 43 7 6 195 30 7 28/02/13 9 3 3 100 17 6 19/03/13 15 4 4 177 20 9 Mean 21 6 3 20 29 0.7 23/03/12 3 3 1.2 17 18 0.9 25/04/12 9 4 2 18 22 0.8 15/05/12 10 5 2 18 22 0.8 21/06/12 13 5 2 21 26 0.8 Healaugh 17/07/12 14 6 2 20 27 0.7 Side 13/08/12 17 7 2 27 32 0.8 BB8 Tributary at 13/09/12 29 11 3 31 42 0.8 Barney Beck 16/10/12 81 14 6 25 58 0.4 21/11/12 46 11 4 22 45 0.5 14/12/12 7 3 2 16 18 0.9 28/01/13 25 6 4 17 27 0.6 28/02/13 6 3 2 17 19 0.9 19/03/13 7 3 2 17 19 0.9 Diss = dissolved, all units are in g/L
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Site Monitoring Pb Diss Pb PNEC Pb Zn Diss Zn PNEC Zn Date Ref Point Measured Estimated RCR Measured Estimated RCR Mean 110 7 15 161 32 5 23/03/12 51 2 24 124 16 8 25/04/12 99 6 16 158 29 6 15/05/12 86 5 16 160 26 6 21/06/12 74 5 15 173 24 7 Barney 17/07/12 81 5 17 169 24 7 Beck d/s 13/08/12 81 4 20 168 22 8 BB9 Healaugh 13/09/12 309 19 16 217 72 3 Side 16/10/12 241 20 12 136 70 2 Tributary 21/11/12 191 17 11 135 64 2 14/12/12 51 3 17 168 18 9 28/01/13 101 7 15 139 29 5 28/02/13 56 3 18 167 19 9 19/03/13 59 4 14 142 22 7 28/05/13 56 3 18 201 19 10 Mean 77 4 17 127 23 5 Barney 31/07/12 72 4 18 97 23 4 BB10 Beck at 23/10/12 115 6 18 115 30 4 Helaugh 28/05/13 34 3 11 99 19 5 Diss = dissolved, all units are in g/L
Total versus dissolved metal concentrations The ratios of total and dissolved metal concentrations were compared with flow rates for each of the monitoring events where water quality samples and flow measurements were taken simultaneously. This was carried out to investigate the variation of total to dissolved metal concentrations under different flow conditions. The objective was to determine whether higher flow conditions caused the total metal concentrations to increase following mobilisation of sediments into suspended solids by higher flow rates. This may occur in spoil tip run-off as well as in the river channels.
Graphs of total versus dissolved concentration ratios against flow rate were plotted for Pb, Zn and Cd. Graphs for each metal were produced in 3 scenarios: for all samples; for river samples only; and for adit samples only. Graphs for Pb and Zn are shown in Figure 12 below. However, no obvious relationship was revealed by the any of the plots, and overall, the ratios of total to dissolved concentrations were approximately equal to 1 for most water quality samples.
This shows that metal concentrations were not increased by mobilisation of sediments during high flow conditions. The upstream sources are likely to be diffuse wastes so comparing total and dissolved concentrations is not conclusive.
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Figure 12. Graphs of total versus dissolved metal ratios against flow
Metal concentrations with respect to flow Graphs of Pb, Zn, Cd concentration against flow are shown in Figure 13 below, for each of the monitoring events where water quality samples and flow measurements were taken simultaneously. The graphs are split into adits (BB4, BB6, BB7) and river sampling sites (BB1, BB3, BB9), where the adits have much lower flow rates than the river.
At the three adits; lead concentrations are somewhat higher at Hard Level (BB4) than at the Dam Drain (BB6) and Spence Level (BB7), whereas zinc and cadmium concentrations are much higher at Hard Level (BB4). Otherwise these metal concentrations don’t appear to show any consistent trends with flow at the adits.
At the river sampling locations in Barney Beck; lead concentrations increase as flow increases at the upstream locations (BB1, BB3), but not at the downstream location (BB9). Zinc and cadmium concentrations remain fairly consistent with flow and both show very similar variation, while concentrations slightly increase with flow at BB3.
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Figure 13. Graphs of metal concentration against flow
Metal loading Metal loading (in g/s) at each monitoring point is calculated using the expression: Loading (g/s) = Dissolved Concentration (g/L) x Flow (L/s)
The table below shows the concentration and loading results for Pb, Zn and Cd from 6 selected monitoring events from the lowest measured flows (Q90) exceeded 90% of the time, to the highest flows (Q15) only exceeded 15% of the time. The monitoring points are listed from upstream (BB1) to downstream (BB9). BB1, BB3 and BB9 are river samples while BB4, BB6 and BB7 (in bold) are mine drainage adits: Hard Level, Dam Drain and Spence Level. The loading values for BB1 to BB7 are compared to the loading at the downstream monitoring point, BB9 and those exceeding the loading at BB9 are high-lighted in pink.
When loadings are considered, the relative impact of each inflow can be compared. The table above shows how metal loading, both entering the study area and inflowing from mine drainage adits, varies from low flow to high flow events and also between the 3 metals under consideration.
From the table below it can be seen that of the 3 mine drainage levels/adits, Hard Level (BB4) had both higher flows and higher Pb, Zn and Cd concentrations than both Dam Drain
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(BB6) and Spence Level (BB7) at all flow conditions. Therefore Hard Level is contributing the most significant proportion of the overall metal loading in the catchment. Zn and Cd loading at Hard Level (BB4) does not change significantly between low to moderate percentile flows and is consistently more than 100% of the loading leaving the study area at BB9, except at the higher flows when the relative impact of Hard Level at Q31 reduces to 70% of BB9 and at the highest flow of Q15 reduces further to 30% of BB9.
Hard Level is the most significant source of Zn and Cd at low to medium flows (up to Q40), whereas at higher flows diffuse sources become more important, although Hard Level remains the largest single source. The concentration of Zn and Cd in the mine water does not significantly vary with flow.
Hard Level is a significant source of Pb and the concentration and flux increase with flow. However, as the river flow increases, the relative contribution of Pb from Hard Level decreases.
Flow Flow Pb Pb Load Zn Zn Load Cd Cd Load Site %ile and Rate conc % of conc % of conc % of Ref g/s g/s g/s Date L/s g/L BB9 g/L BB9 g/L BB9 BB1 1 518 602 24 283 329 5 1.6 2 3 BB3 3 70 244 10 103 357 6 0.7 3 4 Q90 BB4 19 66 1247 50 519 9775 163 4.4 83 127 22/03/12 BB6 3 35 97 4 95 266 4 0.6 2 2 BB7 3 27 69 3 97 247 4 0.6 2 2 BB9 48 51 2480 100 124 6006 100 1.4 65 100 BB1 14 356 5006 108 218 3065 22 1.1 16 14 BB3 23 151 3417 74 131 2965 22 0.7 16 14 Q62 BB4 30 47 1426 31 528 15,952 116 4.4 134 114 28/02/12 BB6 2 12 24 1 90 180 1 0.4 1 1 BB7 4 26 107 2 95 390 3 0.5 2 2 BB9 82 56 4628 100 167 13,753 100 1.4 117 100 BB1 1 729 946 14 245 318 2 1.4 2 1 BB3 13 181 2337 34 121 1562 11 0.8 11 8 Q49 BB4 35 120 4190 60 594 20,739 143 4.8 168 128 17/07/12 BB6 4 72 283 4 113 445 3 0.6 2 2 BB7 5 64 311 4 117 565 4 0.7 3 3 BB9 86 81 6939 100 169 14,532 100 1.5 131 100 BB1 10 512 5143 45 190 1908 9 1.1 11 6 BB3 26 222 5788 50 134 3493 16 0.8 21 12 Q40 BB4 47 109 5131 45 555 26,124 122 4.4 207 115 15/05/12 BB6 3 23 74 1 102 325 2 0.4 1 1 BB7 11 32 337 3 81 860 4 0.5 5 3 BB9 134 86 11,479 100 160 21,480 100 1.3 180 100 BB1 35 684 24,089 61 209 7361 26 1.1 39 17 BB3 54 542 29,215 74 197 10,619 38 1.2 62 27 Q31 BB4 36 247 8868 22 535 19,207 69 4.4 157 68 13/09/12 BB6 4 256 1003 3 194 760 3 1.0 4 2 BB7 4 195 792 2 196 797 3 1.0 4 2 BB9 129 309 39,744 100 217 27,911 100 1.8 230 100 BB1 218 334 72,706 44 150 32,652 28 0.8 180 22 BB3 393 293 115,159 70 135 53,060 46 0.8 305 38 Q15 BB4 62 197 12,221 7 500 31,017 27 4.0 247 31 21/11/12 BB6 13 123 1646 1 165 2209 2 0.6 8 1 BB7 7 72 540 0.3 103 772 1 0.6 5 1 BB9 864 191 164,946 100 135 116,585 100 0.9 807 100
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BB1 and BB9 are the upstream and downstream monitoring points on Barney Beck with flow monitoring and so represent the flows and metal loading entering and leaving the study area. The proportion of metal loading entering the study area at BB1 generally increases as flow increases. This pattern is clear for Zn and Cd, but is more variable for Pb, where the event at Q62 included an unusually high Pb loading at BB1 that exceeded the Pb loading leaving the study area at BB9. Under the highest river flows, the Pb, Zn and Cd concentrations leaving the study area at BB9 increase with flow, leading to a significant increase in metal loading. No significant point source of Pb has been identified but it is most likely arising from diffuse inputs, such as contaminated river sediments and run-off from spoil tips.
The mean metal loadings (in kg/year) entering and leaving the study area and at the main levels are calculated from the means of individual sampling events, as follows.
Mean Mean Concentrations Mean (Min-Max) Loadings Site Monitoring Point Flow (g/L) (kg/year) Ref (L/s) Pb Zn Cd Pb Zn Cd Barney Beck u/s 853 345 2 BB1 76 471 203 1.1 Old Rake (19-3938) (10-1481) (0.1-8) 161 637 5 BB4 Hard Level 38 123 527 4.3 (39-386) (308-979) (3-8) 24 28 0.1 BB6 Dam Drain 6 79 133 0.6 (1-152) (6-119) (0.02-0.5) 11 17 0.1 BB7 Spence Level 5 60 104 0.6 (2-31) (8-30) (0.05-0.2) Barney Beck d/s 914 917 7 BB9 Healaugh Side 192 110 161 1.3 (78-5205) (190-3679) (2-25) Tributary
The table above shows that there is significant mean metal loading entering the study area from the mining sites located upstream. The Pb, Zn and Cd loading entering the study area is 93%, 38% and 29% of the loading leaving it, respectively.
Potential water quality improvements from treating point sources The accompanying MINDAR1 spreadsheet (“Barney Beck display data.xlsm”) has been used to calculate the water quality improvement predicted by treating the main point source identified in the Barney Beck catchment, Hard Level (the tool is only currently able to consider two point sources which is why Spence Level and the Dam Drain have not been included). The benefits of various treatment options have been calculated to show the reduction in metal concentration and loading at the downstream monitoring point (BB9) representing the predicted metal impacts leaving the catchment and entering the River Swale. The predictions were made assuming that 70% and 90% of the Pb, Zn and Cd could be removed from the adit discharge. These were considered for the 9 monitoring events at BB9 from low flow (Q90) to high flow (Q15). The treatment predictions were calculated using the expression: Loading (g/s) = Concentration (g/L) x Flow (L/s)
Calculations were also carried out before the MINDAR tool was available – these are discussed below. There is a single main point source identified in the Barney Beck catchment at Hard Level, with 2 lesser impacts identified at Dam Drain and Spence Level. The benefits of various treatment options have been calculated to show the reduction in
1 MINDAR: Minewater Data and Reporting spreadsheet created by Tim Hearthward (EA).
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metal concentration and metal loading at the downstream flow monitoring point (BB9) representing the predicted metal impacts leaving the catchment and entering the River Swale.
The predictions were made assuming that 50%, 70% and 90% of the Pb, Zn and Cd could be removed from the discharges. The 3 mine drainage adits are located close together (within 100m), and so 2 scenarios were evaluated: treating only Hard Level; and treating all 3 discharges at the same treatment site. These were considered for 9 of the 11 monitoring events (9 flow measurements at BB9) from low flow (Q90) to high flow (Q06). Unfortunately the flows at BB9 were too high for safe flow measurement during the highest flow events: Q09 on 14/12/12 and Q06 on 16/10/12.
Treatment predictions were made by reducing the metal concentrations (and loadings) by 50%, 70% or 90% at one or more adits as required, and deriving the metal load reduction that was passed on downstream. The loading calculation was then used again, to back- calculate the resultant downstream concentrations under the reduced loading with the flows unchanged.
The predicted improvement in EQS/PNEC failure rates at the downstream monitoring point on Barney Beck (BB9) are shown in the table below for the various treatment options under the 9 measured flow conditions. The post-treatment concentrations with fewer results predicted to be below the EQS/PNEC values are high-lighted in green.
No. No. Measured EQS Failures No. Predicted EQS Failures Treatment BB9 Option Pb Pb Zn Zn Cd Pb Pb Zn Zn Cd Results Diss Bio Diss Bio Diss Diss Bio Diss Bio Diss Hard Level 50% 9 9 9 9 9 9 9 9 7 9 9 Hard Level 70% 9 9 9 9 9 9 9 9 4 6 9 Hard Level 90% 9 9 9 9 9 9 9 9 3 4 5 All 3 Levels 50% 9 9 9 9 9 9 9 9 7 9 9 All 3 Levels 70% 9 9 9 9 9 9 9 9 3 6 9 All 3 Levels 90% 9 9 9 9 9 9 9 9 2 3 5 Diss = dissolved, Bio = bioavailable, All 3 Levels = Hard Level, Dam Drain, Spence Level
The predicted treatment results at the downstream monitoring point (BB9) for each of the treatment options and metal removal rates are shown below in 3 tables, one for each metal (Pb, Zn, Cd) for 9 monitoring events from low flow (Q90) to high flow (Q15).
At some monitoring events, the measured metal loading from the adits exceeded the metal loading at a downstream monitoring point. This discrepancy may be due to measurement errors or metal deposition within the catchment. When the treatment scenarios were applied, the theoretical metal loading removed from the catchment exceeded the measured loading downstream, resulting in a negative predicted loading. In these cases, the downstream metal loadings were altered to zero, because the adit treatment could not result in more than 100% success at the downstream monitoring location.
The results with 50% or more reduction in concentration and loading at BB9 are high-lighted in orange and those showing 100% reduction are high-lighted in green.
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Predicted reductions in Pb concentration and loading at BB9 are shown in the table below. Hard + Hard + Hard + Q-Flow Flow Hard Hard Hard Dam + Dam + Dam + %ile (L/s) 50% 70% 90% Spence Spence Spence 50% 70% 90% Q90 48 25% 35% 45% 28% 40% 51% Q62 82 15% 22% 28% 17% 24% 30% Q54 127 27% 37% 48% 28% 39% 50% Q49 86 30% 42% 54% 34% 48% 62% Q42 138 17% 24% 31% 18% 26% 33% Q40 134 22% 31% 40% 24% 34% 43% Q32 123 16% 22% 28% 17% 24% 31% Q31 129 11% 16% 20% 13% 19% 24% Q15 864 4% 5% 7% 4% 6% 8%
Predicted reductions in Zn concentration and loading at BB9 are shown in the table below. Hard + Hard + Hard + Q-Flow Flow Hard Hard Hard Dam + Dam + Dam + %ile (L/s) 50% 70% 90% Spence Spence Spence 50% 70% 90% Q90 48 81% 100% 100% 86% 100% 100% Q62 82 58% 81% 100% 60% 84% 100% Q54 127 51% 72% 92% 53% 74% 96% Q49 86 71% 100% 100% 75% 100% 100% Q42 138 38% 53% 68% 39% 55% 71% Q40 134 61% 85% 100% 64% 89% 100% Q32 123 45% 63% 81% 47% 66% 84% Q31 129 34% 48% 62% 37% 52% 67% Q15 864 13% 19% 24% 15% 20% 26%
Predicted reductions in Cd concentration and loading at BB9 are shown in the table below. Hard + Hard + Hard + Q-Flow Flow Hard Hard Hard Dam + Dam + Dam + %ile (L/s) 50% 70% 90% Spence Spence Spence 50% 70% 90% Q90 48 64% 89% 100% 66% 92% 100% Q62 82 57% 80% 100% 58% 82% 100% Q54 127 46% 65% 83% 47% 66% 85% Q49 86 64% 90% 100% 66% 93% 100% Q42 138 38% 53% 68% 39% 55% 70% Q40 134 58% 81% 100% 59% 83% 100% Q32 123 46% 65% 83% 47% 66% 85% Q31 129 34% 48% 61% 36% 50% 64% Q15 864 15% 21% 28% 16% 23% 29%
The treatment predictions show the following. Pb removal is less significant than Zn and Cd. Treatment is generally more successful at low flows. Treatment is not very effective at the highest flows (Q15). Treating Hard Level alone will be almost as effective as treating all 3 adits. Treating all 3 adits is marginally better than treating just Hard Level. The 3 adits are 100m apart, so co-treatment at the same site is likely to be practical.
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Constraints Land owners and occupiers The main landowners in the Barney Beck catchment are as follows:
Study area: Reeth Sporting Society: The Estate Office, Rothwell, Market Rasen, Lincolnshire, LN7 6BJ.
Bleaberry Gill: Duke of Norfolk Estate: Rupert Drury and Co, Thorn House, Terrington, York, YO60 6PJ.
Contact details for the landowners are available from Robert White at the Yorkshire Dales National Park Authority (see below).
Conservation and heritage designations The designations within Barney Beck catchment are listed and discussed earlier and shown on Figure 5 and on Figure 14 below, which shows two Scheduled Ancient Monuments: Old Gang Smelt Mill in the west and Surrender Smelt Mill in the east. The designated area of Old Gang Smelt Mill includes Hard Level, Dam Level and Spence Level.
In summary, all of the catchment is in the Yorkshire Dales National Park, and is also a SSSI. SPA and SAC. There is also 12ha of ancient woodland at Birk Park Wood near to the Swale confluence.
Figure 14. Map showing the extent of certain Ancient Scheduled Monuments
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Stakeholders Robert White, Senior Historic Environment Officer Yorkshire Dales National Park Authority, Yoredale, Bainbridge, Leyburn, North Yorkshire, DL8 3EL
Reeth Sporting Society: The Estate Office, Rothwell, Market Rasen, Lincolnshire, LN7 6BJ. Duke of Norfolk Estate: Rupert Drury and Co, Thorn House, Terrington, York, YO60 6PJ.
The Federation of Yorkshire Commoners and Moorland Graziers, Kexwith, Marske, Richmond, North Yorkshire, DL11 7EG.
References Dunham, KC and Wilson, AA. 1985. Geology of the North Pennine Orefield: Volume 2 Stainmore to Craven. British Geological Survey.
Environment Agency, 2014. Report on ecological sampling to assess the impacts of metal pollution on Upper River Swale tributaries Gunnerside Gill and Barney Beck. Unpublished report.
Gill, M. 1976. Swaledale: its mines and smelt mills. Northern Mines Research Society.
Yorkshire Dales National Park Authority, 2013. Mitigating Pollution from Historic Lead Mining in the Yorkshire Dales National Park: Barney Beck. Unpublished report.
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Summary The YDNPA report for Barney Beck identified 5 areas of increased run-off and 8 areas of active spoil tip erosion, two of these were considered more significant in the vicinity of Old Gang and Surrender Smelt Mills.
The Barney Beck (GB104027069080) catchment characterisation study has comprised 13 rounds of water quality sampling at 10 locations (129 samples) and 10 rounds of simultaneous flow monitoring at 6 of these locations (59 values). Ecological monitoring has comprised 6 rounds of sampling at 2 locations and 2 further control sites.
The water quality results showed failures of 2013 EQS values for Pb, Zn and Cd in all samples. The most significant source of metal pollution is from Hard Level (BB4) with high concentrations of Pb, Zn, Cd and lower concentrations at low flows from Dam Drain (BB6) and Spence Level (BB7). Significant Pb, Zn, Cd concentrations enter the study site from upstream mining areas at BB1.
Mean metal concentrations leaving the study area (BB9) exceed the EQS values as follows: Current (2013) hardness-based EQS: Pb = 15x, Zn = 3x and Cd = 14x. Bioavailable EQS: Pb = 15x, Zn = 5x.
Metal loading assessment confirmed 900kg/year of Pb, 900kg/year of Zn and 7kg/year of Cd entering the Swale from Barney Beck with most of the Zn and Cd originating from Hard Level and most of the Pb entering the study area from upstream with no source of Pb identified.
Potential treatability assessment showed that treatment would be more successful at low and moderate flows. Metal removal up to 90%at Hard Level (BB4) would significantly reduce Zn and Cd pollution depending on flow rates, and would reduce the frequency of EQS failures at the downstream monitoring point on Barney Beck (BB9).
Recommendations
Scoping study for 14/15 focussed on Hard Level, Spence Level and Dam Drain, as well as diffuse sources at Friarfold Rake and elsewhere.
Yorkshire Dales National Park Authority is keen to help reduce further erosion of mining wastes, and has identified potential water management improvements to reduce run-off from spoil, and spoil tip stabilisation.
10/01/14 John Barber, Technical Specialist in Land Contamination, Name: Date: Updated Aug Yorkshire Area Groundwater & Contaminated Land Team 2014 by HP.
Approval
Pass to Coal Authority for scoping study.
Name: Hugh Potter, WAMM project manager Date: 21 Aug 2014
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