Characterisation & Remediation in a Densely Abstracted Chalk - - PowerPoint PPT Presentation

▶
characterisation remediation in a
SMART_READER_LITE
LIVE PREVIEW

Characterisation & Remediation in a Densely Abstracted Chalk - - PowerPoint PPT Presentation

Jun 22, 2023 236 likes •457 views

Hydrocarbon Plume Characterisation & Remediation in a Densely Abstracted Chalk Aquifer Adrian Bhreathnach MBA MSc PgDip BSc PIEMA Director m: 07743 319710 e: adrian.bhreathnach@seedenvironmental.co.uk Telling a Story ry Background

slide-1
SLIDE 1

Hydrocarbon Plume Characterisation & Remediation in a Densely Abstracted Chalk Aquifer

Adrian Bhreathnach MBA MSc PgDip BSc PIEMA Director

m: 07743 319710 e: adrian.bhreathnach@seedenvironmental.co.uk

slide-2
SLIDE 2

Telling a Story ry

  • Background
  • Objectives
  • The Challenges
  • Implementation & Progress
  • Lessons Learned
slide-3
SLIDE 3

BACKGROUND

slide-4
SLIDE 4

Background – The Sites

  • Active Salad Growing
  • Site A
  • Glass Area 38,500 m2
  • Two Groundwater Abstractions
  • >80,000 litre Kerosene Fuel Storage
  • Site B
  • Glass Area 13,000 m2
  • One Groundwater Abstractions
  • >40,000 litre Kerosene Fuel Storage
  • Glass Area 13,000 m2
  • New Pit Chalk
  • East Anglia
  • Groundwater Source Protection Zone 2

Site A Site B

slide-5
SLIDE 5

Background – The Release

  • Site B – Pump in Abstraction Well located at 25m bgl - Kerosene
  • Subsequently – Kerosene identified in Site A Abstraction Well (220m upgradient)
  • Loss of kerosene heating oil – 4No OST’s - >500 litres / hr usage @ <5oC
  • Source of kerosene identified as underground fuel oil delivery line over

approximately 6 years

slide-6
SLIDE 6

Site A Site B

Backg kground - The Source

  • Chilcott. HPA, 2006.
slide-7
SLIDE 7

Background - The Receptors

slide-8
SLIDE 8

OBJECTIVES

slide-9
SLIDE 9

Stop kerosene LNAPL migration towards identified receptors

Stop

Reduce dissolved concentrations of speciated petroleum hydrocarbons to below remedial target levels

Reduce

Remove LNAPL from aquifer

Remove

Objectives

slide-10
SLIDE 10

THE CHALLENGES

slide-11
SLIDE 11

Overcoming Obstacles & Design (1)

The Sites

  • Business Continuity
  • Glass Houses
  • Groundwater >20m bgl

The Regulations

  • Environmental Permit Regulations & Position Statement 3A
  • Water Resources Act 1991
  • Zero Capacity

The Discharge

  • No Foul Sewer within 1km
  • No Surface Water
  • Contaminated Chalk Aquifer
slide-12
SLIDE 12

Overcoming Obstacles & Design (2)

Data Inconsistencies

  • Consultant Well Sampling – Inconsistent Results & Trends
  • Historical water table levels

Contaminant Transport Routes

  • Fracture Flow
  • Migration Flux Rate (750,000 litres / day)
  • Migration Depths (~22m & ~24m bgl)
slide-13
SLIDE 13

IM IMPLEMENTATION & PROGRESS

slide-14
SLIDE 14

Stage 1

  • Plume Management (Groundwater)
  • Low-Flow Fracture Plume Containment

Stage 2

  • Source Management (Soils)
  • Excavation & Soil Vapour Extraction

Stage 3

  • Active Removal – Free Oil & Dissolved Phase
  • Targeted Flow Abstraction & Optimisation

Stage 4

  • Enhanced Biodegradation (O2 Injection)
  • Natural Attenuation

Remediation Stages

480,000 litres / day 854,000 litres / day

slide-15
SLIDE 15

Key

Free Phase Plume (2017) 67,000m2

Key

Free Phase Plume (2018) 25,000m2

LNAPL Area

2017

LNAPL Area

2018

slide-16
SLIDE 16

Key

>100 µg/l >1,000 µg/l >10,000 µg/l >100,000 µg/l

Dissolved Phase Contamination Plume (2017)

slide-17
SLIDE 17

Dissolved Phase Contamination Plume (2018)

Key

>100 µg/l >1,000 µg/l >10,000 µg/l >100,000 µg/l

slide-18
SLIDE 18

Progress & Next Steps

Site A

  • LNAPL removed – Awaiting rebound assessment
  • Stage 4 – Enhanced O2 biodegradation ongoing
  • >99.9% Reduction in dissolved hydrocarbon concentrations

Site B

  • LNAPL recovery ongoing
  • Delays due to reinjection limitations now resolved
  • Implementing system amendments on western boundary to increase LNAPL recovery area and rates

Site A Site B

slide-19
SLIDE 19

Lessons Learned

slide-20
SLIDE 20

Take Forward Messages

  • Timely regulator engagement and enforcement

flexibility is critical to effective pollution control.

  • Critical project data informing decision making needs

to be consistent, reliable and that any ‘irregularities’ need to be understood prior to remediation design.

  • Innovative site characterization techniques can also be

deployed during remediation to provide effective low- flow and targeted groundwater treatment solutions in Chalk aquifers.

  • A great example of the time and financial benefits of

prioritising conceptual understanding, effective characterization and remediation design.