tata port talbot steelworks · tata port talbot steelworks ground remediation – 24 october 2018 ....

Tata Port Talbot Steelworks Ground Remediation for New Power Plant Development

PAUL TILLEY 24 October 2018

CASE STUDY OVERVIEW

PROJECT OVERVIEW

Delivery of phased and targeted remediation and enabling works within conflicting programme, budget and regulatory

constraints.

CASE STUDY CONTENTS

> Site industrial history and new power plant development proposals > Complex challenges to development due to ground conditions > Detailed site investigation and targeted phased remediation design > Remediation implementation and methods of materials and risk management > Further work and phases of remediation

TATA PORT TALBOT STEELWORKS GROUND REMEDIATION – 24 OCTOBER 2018 2

THE SITE

> Active steelworks site > Long industrial history (since 1920s) > New power generation scheme as part of

long term investment in the site > Power plant to be constructed in previous

coking works area > Significant concerns over buried structures

and ground contamination risks > Significant access limitations due to

existing structures

3 TATA PORT TALBOT STEELWORKS GROUND REMEDIATION – 24 OCTOBER 2018

THE DEVELOPMENT


GROUND INVESTIGATION AND RISK ASSESSMENT

> 2014 to 2015 > 60 Boreholes and Trial Pits / Trenches > Hydrocarbon hotspots including free phase > Metals > Asbestos in Soil > Generic screening against human health

and controlled waters criteria > Derivation of specific thresholds for

controlled waters receptors > RTM spreadsheets used for multiple

chemicals > Soil targets calculated as total

concentrations > Asbestos DQRA to assess risk to end users


REMEDIATION STRATEGY

> Soil remediation targeted at enabling works excavation areas

> Maximum Soil Reuse > High resolution segregation of unsuitable soils > Minimise recontamination of remediated footprints

• Surrounding hotspot free phase / contaminated water recovery

• Lined excavations • Perimeter drainage • Ongoing monitoring

> Management of wider water contamination > Treatment of unsuitable soils > Soil cover system – temporary and long term > Gas risk mitigation in building design > Environmental monitoring > Construction worker risk management plan


EARTHWORKS CHALLENGES

> Significant buried structures, culverts and piles > Sewer Easement > Shallow Perched Water and free phase > Hydrocarbon contaminated soil and water > Presence of ACMs including insulation ‘in

original form’ > Metals contaminated soil > Limited space for materials handling > Targeted remediation of construction footprints

in a wider site: • Need to ‘chase’ hotspots • Need to prevent recontamination


EARTHWORKS CHALLENGES


EARTHWORKS SOLUTIONS – SOIL MANAGEMENT

> Excavate and fill in ‘strips’ > Segregation into small material ‘batches’ > On site analysis to support rapid decision making

• Classification and sentencing of batches • Rapid verification of hotspot removal • Materials tracking and traffic light reporting on site

> Environmental Monitoring • Air • Water • Noise

> DoWCoP declaration for direct re-use of soil and

use of treated soil


EARTHWORKS SOLUTIONS


EARTHWORKS SOLUTIONS – ENVIRONMENTAL MONITORING


Off Site Noise Receptors

PM10 and Depositional Dust

Airborne Fibres

EARTHWORKS SOLUTIONS – WATER MANAGEMENT

> Perched water pumping from excavations > Holding lagoon and temporary water treatment

plant > Membranes installed in sides of excavations > Perimeter drainage within excavations > Targeted removal of contaminated water from

surrounding area > Long term monitoring of surrounding

groundwater and drains


MOBILE LABORATORY CHALLENGES

> Complex matrix with a high total TPH but low naphthalene and benzene targets

> Screening for hydrocarbons is not sufficient

> Wide range of potential contaminants – metals, hydrocarbons, inorganics

> Peaks in sample numbers when space and programme constraints were greatest


MOBILE LABORATORY APPLICATION

> Controlled laboratory environment using purpose built mobile unit

> Metals by XRF > Total hydrocarbons by UV Fluorescence > Speciated BTEX and Naphthalene by Gas

Chromatography > Inorganics by colourimetric methods as required > Initial DMA and ongoing QA procedures > Dedicated analyst and second sampler / analyst in

peak times > AGS based data management and reporting system

– real time interpretation


ON SITE ANALYSIS QUALITY CONTROL AND DEMONSTRATION OF METHOD APPLICABILITY (DMA)


> Controlled Environment – site lab is best > Qualified and Trained Staff > Method Validation > Sample preparation / drying > Instrument and Method Calibration > In batch QC Checks – standard and blanks

> Site specific validation (DMA) > 20 or more duplicate samples > On and off site analysis correlation > Establish correction factors > Decision making windows for 90–95%

certainty around critical concentration ranges

VERIFIED REMEDIATION TO DATE AND ONGOING WORK

> Three building footprint areas successfully excavated, filled and verified

> 25000 m3 of reused soil placed and verified > Circa 1000 m3 of water removed from excavations and surrounding

areas and treated > Significant volumes of ACM removed from site > Building slabs installed with gas membranes > 7500 m3 of soils unsuitable for direct re-use undergoing stabilisation

treatability trials > Treated soils to be used in landscaping > Cover soils to be placed > Water monitoring and assessment to continue > Further phases of power plant development?


tata port talbot steelworks · tata port talbot steelworks ground remediation – 24 october 2018 ....

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