it’s not just flow. the importance of groundwater chemistry in ...€¦ · it’s not just flow....
TRANSCRIPT
It’s not just flow. The importance ofgroundwater chemistry in superficial quarryapplications: a case study
Dr Richard Mitchener1, Anna Butler & Dan Jefferies2
Atkins Limited1 Now at EDF Energy; 2 now at Jacobs UK
Introduction
• Any project that involves digging holes can affect groundwater – and affectinggroundwater can have an effect on ecology, archaeology and even sacred sites
• Habitats Directive, Birds Directive, Ramsar treaty and Water Framework Directive havesignificantly 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 environmentalregulator
• 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 HabitatCreation and Inert Filling
Site Location
• The site comprised fouragricultural fields interspersedwith mature woodland
• Upwood Lies 2km to the northeast of Tubney
• 1.5 km to the north-west ofthe village of Cothill
Reproduced from a 1:50,000 Landranger Ordnance Surveydigital 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 (appropriateassessment)
• “…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 mineralsprojects.
7
What does this mean?
23 July 2019 8
• Valley mireð water isprobably important…
• Dewatering?• Changes to storage• Changes to drainage and runoff
characteristics?• Alkaline fenð chemistry is
probably important…• Changes to water balance• Groundwater/runoff
• Remember “…no adverseeffect…”
Works Undertaken at Site
• Previous ground investigations undertaken inApril and May 2006 to establish the extent andquality of the mineral deposit and installation ofboreholes.
• Installation of groundwater level monitoringequipment in 6 wells Nov 2006 (in (Feb 2007)
• Installation of surface water level monitoringequipment in Cothill Fen and Parsonage Moor(April 2007 and June 2007)
• Installation of a gauge board in Hitchcopse Pitpond in Feb 2007
• Monthly groundwater and surface water qualitymonitoring
• Permeability testing in a range of boreholes (June2007) as part of an MSc project
• Met station already at nearby site
Geology & Hydrogeology
A g e S t r a t a A p p r o x i m a t e T h i c k n e s s
Q u a t e r n a r yD r i f t
A l lu v i u m ( c l a y , s i l t a n d s a n d ) , p e a t a n ds a n d s a n d g r a v e l s
U p p e r J u r a s s i c U p p e r C o r a l l i a n S a n d ( K i n g s t o n F o r m a t i o n ) 1 0 - 2 0 m
U p p e r J u r a s s i c L o w e r C o r a l l i a n S i l t ( H a z e l b u r y B r y a nF o r m a t i o n )
0 - 1 5 m
U p p e r J u r a s s i c L o w e r C o r a l l i a n C l a y 0 - 2 2 m
U p p e r J u r a s s i c O x f o r d C la y 9 0 - 1 0 0 m
Groundwater monitoring
23 July 2019 11
BH08 Groundwater Levels and Rainfall Data
78.90
78.91
78.92
78.93
78.94
78.95
78.96
78.97
01/0
3/20
07 0
0:00
01/0
3/20
07 0
2:00
01/0
3/20
07 0
4:00
01/0
3/20
07 0
6:00
01/0
3/20
07 0
8:00
01/0
3/20
07 1
0:00
01/0
3/20
07 1
2:00
01/0
3/20
07 1
4:00
01/0
3/20
07 1
6:00
01/0
3/20
07 1
8:00
01/0
3/20
07 2
0:00
01/0
3/20
07 2
2:00
02/0
3/20
07 0
0:00
02/0
3/20
07 0
2:00
02/0
3/20
07 0
4:00
02/0
3/20
07 0
6:00
02/0
3/20
07 0
8:00
02/0
3/20
07 1
0:00
02/0
3/20
07 1
2:00
02/0
3/20
07 1
4:00
02/0
3/20
07 1
6:00
02/0
3/20
07 1
8:00
02/0
3/20
07 2
0:00
02/0
3/20
07 2
2:00
03/0
3/20
07 0
0:00
03/0
3/20
07 0
2:00
03/0
3/20
07 0
4:00
03/0
3/20
07 0
6:00
03/0
3/20
07 0
8:00
03/0
3/20
07 1
0:00
03/0
3/20
07 1
2:00
03/0
3/20
07 1
4:00
03/0
3/20
07 1
6:00
03/0
3/20
07 1
8:00
03/0
3/20
07 2
0:00
03/0
3/20
07 2
2:00
04/0
3/20
07 0
0:00
Date
Gro
undw
ater
Lev
el (m
AOD)
0
0.5
1
1.5
2
2.5
3
3.5
Rain
fall
(mm
)
Hourly Rainfall (mm) Groundwater Level (mAOD)
BH02 Groundwater Levels and Rainfall Data
84.134
84.136
84.138
84.140
84.142
84.144
84.146
84.148
84.150
84.152
84.154
01/0
3/20
07 0
0:00
01/0
3/20
07 0
2:00
01/0
3/20
07 0
4:00
01/0
3/20
07 0
6:00
01/0
3/20
07 0
8:00
01/0
3/20
07 1
0:00
01/0
3/20
07 1
2:00
01/0
3/20
07 1
4:00
01/0
3/20
07 1
6:00
01/0
3/20
07 1
8:00
01/0
3/20
07 2
0:00
01/0
3/20
07 2
2:00
02/0
3/20
07 0
0:00
02/0
3/20
07 0
2:00
02/0
3/20
07 0
4:00
02/0
3/20
07 0
6:00
02/0
3/20
07 0
8:00
02/0
3/20
07 1
0:00
02/0
3/20
07 1
2:00
02/0
3/20
07 1
4:00
02/0
3/20
07 1
6:00
02/0
3/20
07 1
8:00
02/0
3/20
07 2
0:00
02/0
3/20
07 2
2:00
03/0
3/20
07 0
0:00
03/0
3/20
07 0
2:00
03/0
3/20
07 0
4:00
03/0
3/20
07 0
6:00
03/0
3/20
07 0
8:00
03/0
3/20
07 1
0:00
03/0
3/20
07 1
2:00
03/0
3/20
07 1
4:00
03/0
3/20
07 1
6:00
03/0
3/20
07 1
8:00
03/0
3/20
07 2
0:00
03/0
3/20
07 2
2:00
04/0
3/20
07 0
0:00
Date
Gro
undw
ater
Lev
els
(mA
OD)
0
0.5
1
1.5
2
2.5
3
3.5
Rainfall (mm
)
Hourly Rainfal l (mm) Groundwater Level (mAOD)
BHNR1 Groundwater Levels and Rainfall Data
80.75
80.76
80.77
80.78
80.79
80.80
80.81
80.82
01/0
3/20
07 0
0:00
01/0
3/20
07 0
2:00
01/0
3/20
07 0
4:00
01/0
3/20
07 0
6:00
01/0
3/20
07 0
8:00
01/0
3/20
07 1
0:00
01/0
3/20
07 1
2:00
01/0
3/20
07 1
4:00
01/0
3/20
07 1
6:00
01/0
3/20
07 1
8:00
01/0
3/20
07 2
0:00
01/0
3/20
07 2
2:00
02/0
3/20
07 0
0:00
02/0
3/20
07 0
2:00
02/0
3/20
07 0
4:00
02/0
3/20
07 0
6:00
02/0
3/20
07 0
8:00
02/0
3/20
07 1
0:00
02/0
3/20
07 1
2:00
02/0
3/20
07 1
4:00
02/0
3/20
07 1
6:00
02/0
3/20
07 1
8:00
02/0
3/20
07 2
0:00
02/0
3/20
07 2
2:00
03/0
3/20
07 0
0:00
03/0
3/20
07 0
2:00
03/0
3/20
07 0
4:00
03/0
3/20
07 0
6:00
03/0
3/20
07 0
8:00
03/0
3/20
07 1
0:00
03/0
3/20
07 1
2:00
03/0
3/20
07 1
4:00
03/0
3/20
07 1
6:00
03/0
3/20
07 1
8:00
03/0
3/20
07 2
0:00
03/0
3/20
07 2
2:00
Date
Gro
undw
ater
Lev
els
(mAO
D)
0
0.5
1
1.5
2
2.5
3
3.5
Rainfall (mm
)
Hourly Rainfall (mm) Groundwater Level (mAOD)
BH06 Groundwater Levels and Rainfall Data
82.85
82.86
82.86
82.87
82.87
82.88
82.88
01/0
3/20
07 0
0:00
01/0
3/20
07 0
2:00
01/0
3/20
07 0
4:00
01/0
3/20
07 0
6:00
01/0
3/20
07 0
8:00
01/0
3/20
07 1
0:00
01/0
3/20
07 1
2:00
01/0
3/20
07 1
4:00
01/0
3/20
07 1
6:00
01/0
3/20
07 1
8:00
01/0
3/20
07 2
0:00
01/0
3/20
07 2
2:00
02/0
3/20
07 0
0:00
02/0
3/20
07 0
2:00
02/0
3/20
07 0
4:00
02/0
3/20
07 0
6:00
02/0
3/20
07 0
8:00
02/0
3/20
07 1
0:00
02/0
3/20
07 1
2:00
02/0
3/20
07 1
4:00
02/0
3/20
07 1
6:00
02/0
3/20
07 1
8:00
02/0
3/20
07 2
0:00
02/0
3/20
07 2
2:00
03/0
3/20
07 0
0:00
03/0
3/20
07 0
2:00
03/0
3/20
07 0
4:00
03/0
3/20
07 0
6:00
03/0
3/20
07 0
8:00
03/0
3/20
07 1
0:00
03/0
3/20
07 1
2:00
03/0
3/20
07 1
4:00
03/0
3/20
07 1
6:00
03/0
3/20
07 1
8:00
03/0
3/20
07 2
0:00
03/0
3/20
07 2
2:00
04/0
3/20
07 0
0:00
Date
Gro
undw
ater
Lev
el (m
AO
D)
0
0.5
1
1.5
2
2.5
3
3.5
Rainfall (mm
)
Hourly Rainfall (mm) Groundwater Level (mAOD)
Hydrogeology – Groundwater divide• The groundwater
contours have identified agroundwater divide
• South easterlygroundwater flow to theeast
• Southerly and southwesterly flow to the west
• Feb 2007 contours
Surface water levels
• Hitchcopse Pit pond, Cothill Fen andParsonage Moor.
• Continual monitoring data - Water levelsin Parsonage Moor are approximately0.6m higher than those at Cothill Fen.
• The fluctuation of surface water levels inCothill
• Fen and Parsonage Moor are small witha range of 0.08m and 0.01m respectively.
• The water levels in Hitchcopse Pit pondhave been taken from a gauge boardinstalled in the pond and are recorded asfluctuating by approximately 0.095m.
• The continual surface water monitoringdata shows constant fluctuations insurface water levels over the monitoringperiods.
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
23 July 2019 15
• Natural England concerned thatreduced unsaturated zone wouldreduce alkalinity
• Potential to affect the conservationstatus (although science was lacking)
• Detailed monitoring to gather data overseveral years – groundwater and surfacewater
• Able to show no correlation betweengroundwater beneath the site and fenwater
• Percolation through leaf litter aroundboundaries identified as key process –these areas left on place.
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 ofsurface water or groundwater
• Hydrogeological Risk Assessment (HRA) completed compliance with Groundwater andLandfill Directives
• No fertilizers, pesticides or other agricultural chemicals would be applied to Field 2 – habitatrestoration
• Field was agricultural and consequently agricultural chemicals were applied – beneficialchange?
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 Windand Sweetman Case C-323/17, 2018]
• But lots of mitigation is simply good practice? Do we have to assumedevelopers are cowboys?
• UK courts slightly more pragmatic e.g. Langdon [2019] EWHC 597