It's Not Just Flow. the Importance Of

It’s not just flow. The importance of groundwater chemistry in superficial quarry applications: a case study

Dr Richard Mitchener1, Anna Butler & Dan Jefferies2 Atkins Limited 1 Now at EDF Energy; 2 now at Jacobs UK Introduction

• Any project that involves digging holes can affect groundwater – and affecting groundwater can have an effect on ecology, archaeology and even sacred sites • Habitats Directive, Birds Directive, Ramsar treaty and Water Framework Directive have significantly increased scrutiny in recent years • SSSIs getting similar protection/scrutiny? • Recent(ish) court judgements have moved the goalposts? • Natural heritage regulators just as important as the planners and the environmental regulator • Non-statutory stakeholders can help or hinder… • Understanding key issues and concerns early is critical • Gather the right data, at the right resolution

23 July 2019 2 Case Study

• Client: Hills Quarry Products Limited • Site: Upwood Park, Oxfordshire • Proposal: Mineral Extraction and Restoration for Low Level Habitat Creation and Inert Filling Site Location

• The site comprised four agricultural fields interspersed with mature woodland • Upwood Lies 2km to the north east of Tubney • 1.5 km to the north-west of the village of Cothill

Reproduced from a 1:50,000 Landranger Ordnance Survey digital map data © Crown copyright 2004. All rights reserved. Licence number 0100031673. Conservation Sites • Cothill Fen and Parsonage Moor Nature Reserve (SAC & SSSI) • Dry Sandford Pit (geological SSSI) • Hitchcopse Pit Nature Reserve (SSSI) Habitats Regulations

• List of Sites proposed by Secretary of State, important for • Habitats (Annex I) • Species (Annex II) • Competent Authority must review planning applications (appropriate assessment) • “…no adverse effect…” • “precautionary principle” • IROPI exception allowed, but highly unlikely to apply minerals sites • Case law reinforces the very high bar

23 July 2019 6 Water Framework Directive

• Integrated management of catchments • Need to achieve and maintain “good” status for groundwater and surface water • Complex series of tests applied by Competent Authority (EA) • “groundwater dependent terrestrial ecosystems” given special importance • “WFD Assessment” needed – methodology developing • Similar “get out” as for Habitats directive (Art. 4.7) but again unlikely to apply to minerals projects.

7 What does this mean?

• Valley mire ð water is probably important… • Dewatering? • Changes to storage • Changes to drainage and runoff characteristics? • Alkaline fen ð chemistry is probably important… • Changes to water balance • Groundwater/runoff • Remember “…no adverse effect…”

23 July 2019 8 Works Undertaken at Site

• Previous ground investigations undertaken in April and May 2006 to establish the extent and quality of the mineral deposit and installation of boreholes. • Installation of groundwater level monitoring equipment in 6 wells Nov 2006 (in (Feb 2007) • Installation of surface water level monitoring equipment in Cothill Fen and Parsonage Moor (April 2007 and June 2007) • Installation of a gauge board in Hitchcopse Pit pond in Feb 2007 • Monthly groundwater and surface water quality monitoring • Permeability testing in a range of boreholes (June 2007) as part of an MSc project • Met station already at nearby site Geology & Hydrogeology

A g e S t r a t a Approxim ate Thickness

Q u a t e r n a r y Alluvium (clay, silt and sand), peat and D r i f t sands and gravels

Upper Jurassic Upper Corallian Sand (Kingston Form ation) 1 0 - 2 0 m

Upper Jurassic Lower Corallian Silt (Hazelbury Bryan 0 - 1 5 m F o r m a t i o n )

Upper Jurassic Lower Corallian Clay 0 - 2 2 m

Upper Jurassic O xford Clay 9 0 - 1 0 0 m Groundwater monitoring

BH08 Groundwater Levels and Rainfall Data BH06 Groundwater Levels and Rainfall Data

82.88 3.5 78.97 3.5

3 78.96 3 82.88

2.5 78.95 2.5 82.87 Rainfall (mm) Rainfall 2 78.94 2

82.87

1.5 78.93 1.5 Rainfall Rainfall (mm)

Groundwater (mAOD) Level Groundwater 82.86 Groundwater Level (mAOD) Level Groundwater 1 78.92 1

82.86 78.91 0.5 0.5

82.85 0 78.90 0 01/03/2007 00:00 01/03/2007 02:00 01/03/2007 04:00 01/03/2007 06:00 01/03/2007 08:00 01/03/2007 10:00 01/03/2007 12:00 01/03/2007 14:00 01/03/2007 16:00 01/03/2007 18:00 01/03/2007 20:00 01/03/2007 22:00 01/03/2007 00:00 02/03/2007 02:00 02/03/2007 04:00 02/03/2007 06:00 02/03/2007 08:00 02/03/2007 10:00 02/03/2007 12:00 02/03/2007 14:00 02/03/2007 16:00 02/03/2007 18:00 02/03/2007 20:00 02/03/2007 22:00 02/03/2007 00:00 03/03/2007 02:00 03/03/2007 04:00 03/03/2007 06:00 03/03/2007 08:00 03/03/2007 10:00 03/03/2007 12:00 03/03/2007 14:00 03/03/2007 16:00 03/03/2007 18:00 03/03/2007 20:00 03/03/2007 22:00 03/03/2007 00:00 04/03/2007

01/03/2007 01/03/2007 00:00 01/03/2007 02:00 01/03/2007 04:00 01/03/2007 06:00 01/03/2007 08:00 01/03/2007 10:00 01/03/2007 12:00 01/03/2007 14:00 01/03/2007 16:00 01/03/2007 18:00 01/03/2007 20:00 01/03/2007 22:00 02/03/2007 00:00 02/03/2007 02:00 02/03/2007 04:00 02/03/2007 06:00 02/03/2007 08:00 02/03/2007 10:00 02/03/2007 12:00 02/03/2007 14:00 02/03/2007 16:00 02/03/2007 18:00 02/03/2007 20:00 02/03/2007 22:00 03/03/2007 00:00 03/03/2007 02:00 03/03/2007 04:00 03/03/2007 06:00 03/03/2007 08:00 03/03/2007 10:00 03/03/2007 12:00 03/03/2007 14:00 03/03/2007 16:00 03/03/2007 18:00 03/03/2007 20:00 03/03/2007 22:00 04/03/2007 00:00 Date Date Hourly Rainfall (mm) Groundwater Level (mAOD) Hourly Rainfall (mm) Groundwater Level (mAOD)

BH02 Groundwater Levels and Rainfall Data BHNR1 Groundwater Levels and Rainfall Data

84.154 3.5 80.82 3.5

84.152 3 80.81 3 84.150

2.5 80.80 2.5 84.148

84.146 (mm) Rainfall Rainfall Rainfall (mm) 80.79 2 2

84.144

80.78 1.5 1.5 84.142 Groundwater Levels (mAOD) Groundwater (mAOD) Groundwater Levels 84.140 80.77 1 1

84.138 80.76 0.5 0.5 84.136

80.75 0 84.134 0 01/03/2007 00:00 01/03/2007 02:00 01/03/2007 04:00 01/03/2007 06:00 01/03/2007 08:00 01/03/2007 10:00 01/03/2007 12:00 01/03/2007 14:00 01/03/2007 16:00 01/03/2007 18:00 01/03/2007 20:00 01/03/2007 22:00 01/03/2007 00:00 02/03/2007 02:00 02/03/2007 04:00 02/03/2007 06:00 02/03/2007 08:00 02/03/2007 10:00 02/03/2007 12:00 02/03/2007 14:00 02/03/2007 16:00 02/03/2007 18:00 02/03/2007 20:00 02/03/2007 22:00 02/03/2007 00:00 03/03/2007 02:00 03/03/2007 04:00 03/03/2007 06:00 03/03/2007 08:00 03/03/2007 10:00 03/03/2007 12:00 03/03/2007 14:00 03/03/2007 16:00 03/03/2007 18:00 03/03/2007 20:00 03/03/2007 22:00 03/03/2007

Date 01/03/2007 00:00 01/03/2007 02:00 01/03/2007 04:00 01/03/2007 06:00 01/03/2007 08:00 01/03/2007 10:00 01/03/2007 12:00 01/03/2007 14:00 01/03/2007 16:00 01/03/2007 18:00 01/03/2007 20:00 01/03/2007 22:00 02/03/2007 00:00 02/03/2007 02:00 02/03/2007 04:00 02/03/2007 06:00 02/03/2007 08:00 02/03/2007 10:00 02/03/2007 12:00 02/03/2007 14:00 02/03/2007 16:00 02/03/2007 18:00 02/03/2007 20:00 02/03/2007 22:00 03/03/2007 00:00 03/03/2007 02:00 03/03/2007 04:00 03/03/2007 06:00 03/03/2007 08:00 03/03/2007 10:00 03/03/2007 12:00 03/03/2007 14:00 03/03/2007 16:00 03/03/2007 18:00 03/03/2007 20:00 03/03/2007 22:00 04/03/2007 00:00 Date Hourly Rainfall (mm) Groundwater Level (mAOD) Hourly Rainfall (mm) Groundwater Level (mAOD)

23 July 2019 11 Hydrogeology – Groundwater divide • The groundwater contours have identified a groundwater divide • South easterly groundwater flow to the east • Southerly and south westerly flow to the west • Feb 2007 contours Surface water levels

• Hitchcopse Pit pond, Cothill Fen and Parsonage Moor. • Continual monitoring data - Water levels in Parsonage Moor are approximately 0.6m higher than those at Cothill Fen. • The fluctuation of surface water levels in Cothill • Fen and Parsonage Moor are small with a range of 0.08m and 0.01m respectively. • The water levels in Hitchcopse Pit pond have been taken from a gauge board installed in the pond and are recorded as fluctuating by approximately 0.095m. • The continual surface water monitoring data shows constant fluctuations in surface water levels over the monitoring periods. Groundwater quality

• Groundwater Quality was monitored at the site • Alkalinity, ammoniacal nitrogen, calcium, manganese concentrations were higher to the west of the groundwater divide • The maximum sulphate concentrations have been identified in BH08 near Cothill Fen and BH07 to the east of the groundwater divide • The data suggested that the groundwater chemistry was different each side of the groundwater divide Alkalinity & ecology • Natural England concerned that reduced unsaturated zone would reduce alkalinity • Potential to affect the conservation status (although science was lacking) • Detailed monitoring to gather data over several years – groundwater and surface water • Able to show no correlation between groundwater beneath the site and fen water • Percolation through leaf litter around boundaries identified as key process – these areas left on place.

23 July 2019 15 Where did we end up?

• Flow impacts • No sub-water table quarrying or infilling – unsaturated zone retained • No infilling at all in Field 2 • Fields 1,3, & 4 restored to existing • Different infiltration ability of the inert fill as opposed to sand – mitigated via SuDS • Detailed design needed to take account of recovered materials • Groundwater and Surface Water Quality • By definition the total leachability and pollutant content of inert waste, and the ecotoxicity of the leachate produced, must be insignificant and in particular not endanger the quality of surface water or groundwater • Hydrogeological Risk Assessment (HRA) completed compliance with Groundwater and Landfill Directives • No fertilizers, pesticides or other agricultural chemicals would be applied to Field 2 – habitat restoration • Field was agricultural and consequently agricultural chemicals were applied – beneficial change? What’s changed over the last decade?

• EIA directive now explicitly requires monitoring… • Destruction of 0.54% of a priority habitat can affect the ”integrity” [Sweetman v. An Bord Pleanála, Case C-258/11, 2013] • How does this translate to less clear-cut cases? • Can’t take mitigation into account at screening [People Over Wind and Sweetman Case C-323/17, 2018] • But lots of mitigation is simply good practice? Do we have to assume developers are cowboys? • UK courts slightly more pragmatic e.g. Langdon [2019] EWHC 597