Frankis Solutions Limited Thames Barrier Park East Silvertown Remedial Method

FRANKIS SOLUTIONS LIMITED THAMES BARRIER PARK EAST SILVERTOWN REMEDIAL METHOD STATEMENT

Report Reference

Date of Issue

Author

Checked

Approved

RMS-S3707-08-14

January 2008

RC/DLB

RC

RC

THAMES BARRIER PARK EAST, SILVERTOWN

REMEDIAL METHOD STATEMENT TABLE OF CONTENTS

SECTION 1 SECTION 2

SECTION 3 SECTION 4

SECTION 5

SECTION 6

INTRODUCTION ...............................................................................................2 THE SITE & GROUND CONDITIONS...............................................................2 2.1 INTRODUCTION ........................................................................................2 2.2 GEOLOGY ................................................................................................2 2.3 HYDROGEOLOGY .....................................................................................2 2.4 HYDROLOGY ............................................................................................2 2.5 IN-GROUND OBSTRUCTIONS .....................................................................2 2.6 FIELD EVIDENCE OF CONTAMINATION.........................................................2 2.7 CONTAMINATION TARGETS........................................................................2 2.8 SOIL CONTAMINATION...............................................................................2 CONTRACT OBJECTIVES & REQUIREMENTS..............................................2 REMEDIAL METHOD STATEMENT .................................................................2 4.1 INTRODUCTION ........................................................................................2 4.2 SOLID SOURCE REMEDIATION....................................................................2 4.3 STREAM E – BIOREMEDIATION ...................................................................2 4.4 WASTEWATER HANDLING ..........................................................................2 4.5 WASTE TYPES AND QUANTITIES.................................................................2 4.6 ACCEPTANCE PROCEDURES .....................................................................2 4.7 QUARANTINE AREAS .................................................................................2 4.8 COMMISSIONING, OPERATION AND MAINTENANCE ......................................2 ENVIRONMENTAL MONITORING AND AUDIT ...............................................2 5.1 INTRODUCTION ........................................................................................2 5.2 MONITORING............................................................................................2 5.3 BASELINE MONITORING.............................................................................2 5.4 POLLUTION CONTROL – DUSTS, FIBRES, PARTICULATES, VAPOURS, GASES, AEROSOLS AND ODOURS ..........................................................................2 5.5 ASBESTOS ...............................................................................................2 5.6 RADIATION...............................................................................................2 5.7 ODOURS ..................................................................................................2 5.8 VOC EMISSIONS .......................................................................................2 5.9 CONTROL OF NOISE..................................................................................2 VALIDATION......................................................................................................2

APPENDIX 1 ...............................................................................................................................
Site Plan (Reference S3707-303-001-A2) APPENDIX 2 ...............................................................................................................................
Monitoring Plan (Reference: MP-S3707-07-147)

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REMEDIAL METHOD STATEMENT SECTION 1

SECTION 2

INTRODUCTION 1.1

Merebrook Science & Environment Ltd (Merebrook) has been retained by Frankis Solutions Ltd (Frankis) to provide consultancy advice and validation services in relation to a contaminated land remediation contract at Thames Barrier Park East, Silvertown, London. The works are being designed by White Young Green Environmental (WYGE) on behalf of their developer client group: Barratt East London (Barratt), Taylor Wimpey Developments Ltd and the London Development Agency.

1.2

The objectives of this report are to set out the proposals for a remediation strategy at the site to achieve the WYGE design.

1.3

The appraisal of the site and remedial requirements is based on a series of documents prepared by WYGE and provided to Frankis under cover of a letter from Barratt dated 28 July 2007, the principal documents being: i.

Draft for Review, Remediation Strategy Statement, issue V5d, July 07,

ii.

Specification, Primary Remediation Works, Design and Construction, issue V2d, 17 July 07.

1.4

It is noted that the contract relates only to a subset of the wider development site comprising specified areas of remediation within the northwest of the wider site.

1.5

This report has been prepared for Frankis for the sole purpose described above and no duty of care to any third party is implied or offered. Third parties making reference to this report should consult Frankis and Merebrook as to the extent to which the findings may be appropriate for their use.

THE SITE & GROUND CONDITIONS 2.1

INTRODUCTION

2.1.1

The wider redevelopment site is ‘T’ shaped and is located at the ten-character grid reference: 541700 (E) 180300 (N). The following appraisal relates to contamination within the proposed remediation area located on the northwest section of the ‘T’ (Area 1) and to a smaller area located in the north of the site (Area 2).

2.1.2

The site and surrounding area were formerly a tar distillery and chemical works and the resulting ground contamination is widespread. The site operated from approximately the 1850s as a tar works and was eventually disused in 1970s. The contaminants of concern associated with the former tar works include polyaromatic hydrocarbons (PAH), Total Petroleum Hydrocarbons (TPH), benzene, toluene, ethylbenzene and xylene (BTEX), phenols and heavy metals.

2.1.3

The elevated extension of the Docklands Light Railway (DLR) passes over the north of the site and it is understood that any works in this area will be subject to

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REMEDIAL METHOD STATEMENT approval by DLR engineers. The majority of the site is currently derelict and surfaced with soft ground, with approximately 5 % hardstanding. 2.1.4

The proposed development comprises a mixture of managed residential housing and retail end use. This will include the creation of basements although preliminary drawings indicate the basement construction will not involve the excavation of significant depths of existing soils (not more than 2.0 m).

2.1.5

Adjacent to the south west of the site is Thames Barrier Park. It is understood that this area was also historically occupied in part by the tar works but was remediated to some extent in the 1990s. Initial remediation of the adjacent site is understood to have involved the removal of mass concrete substructures and draining of buried tanks and re-profiling of the land. The concrete was crushed and graded to form a protective layer to the site while the final development layout was determined. Once this was finalised the existing crushed concrete was stripped and further cut and fill undertaken to form the required contours. Following removal of any further visibly contaminated material the crushed concrete was replaced and a capillary break layer placed above this. This was covered by geotextile before the final depth of subsoil and topsoil was placed.

2.2

GEOLOGY

2.2.1

The geological sheet for the area indicates alluvium (with peat layers) overlying River Terrace Gravels, Lambeth Group and Thanet Sand, with Chalk at depth.

2.2.2

With reference to the exploratory hole records from various phases of investigation, made ground has been found to be ubiquitous across the site to depths of between 0.9 and 6.1 m bgl. The Lambeth Group has clay layers towards the top of the stratum which appear to act as an aquitard to downward migration of groundwater. The Chalk is understood to be present at approximately 35 m bgl.

2.3

HYDROGEOLOGY

2.3.1

The River Terrace Gravels are classified as a Minor Aquifer. The lower part of the Lambeth Group, Thanet Sands and Upper Chalk are classified as a Major Aquifer. Groundwater in the Lambeth, Thanet and Chalk are classed together as a major aquifer because water in these strata is considered to be in hydraulic continuity.

2.3.2

Several rounds of groundwater monitoring have been performed including recording groundwater levels in dual installations (i.e. two installations in the same borehole but with differing response zones). Dual phase (LNAPL/water) dip-meters do not appear to have been used during the monitoring. In some areas the groundwater levels within the made ground/alluvium layer was the same as that recorded in the gravels and the perched water and groundwater are considered to be in continuity. In other boreholes, the water levels recorded in the made ground/alluvium stratum were higher than those in the gravels and in these locations the perched water body may be considered to be independent of the groundwater table.

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REMEDIAL METHOD STATEMENT 2.3.3

Groundwater in the river terrace gravels is reported by WYGE to be tidally influenced and impacted by saline waters to some extent. The groundwater in the lower part of the Lambeth Group, the Thanet Sands and the Chalk major aquifer is not considered to be in direct continuity with the River Thames.

2.4

HYDROLOGY

2.4.1

The River Thames located approximately 70 m to the south of the main site boundary is the nearest surface water receptor to the site. The Thames is approximately 230 m from the southernmost boundary of the main north-western remediation zone.

2.5

IN-GROUND OBSTRUCTIONS

2.5.1

Historical structures are located throughout the northwestern zone. These were developed in different phases throughout the 19th and 20th centuries. It is likely that obstructions encountered during investigation are associated with the foundations of these structures or their demolition materials.

2.5.2

Most obstructions were found at an approximate depth of 3 m bgl, and were found to be concrete slabs of approximately 300 mm thickness. In several trial pits remainders of brick walls were found, as described in field and trial pit logs TT504, TT505 and TT406i, suggesting that most of the historical structures and foundations still remain. Other obstructions encountered include pipes and brick and concrete rubble. Again all of these occur at depths of approximately 2.5 to 3.5 mbgl. Obstructions were found in just over half of all exploratory locations.

2.6

FIELD EVIDENCE OF CONTAMINATION

2.6.1

Over 90 % of the exploratory locations showed significant visual and olfactory evidence of contamination. Olfactory contamination occurred from ground level to maximum observed depths of 47 m bgl. Phenolic odours occurred down to a depth of 12 m bgl, chemical and organic odours were found to a depth of 5 m bgl, while hydrocarbon and creosote odours occurred frequently at variable depths. Creosote encountered as liquid and tarry liquor was found in five locations and occurred at approximately 3 to 4 m bgl. Bitumen and tar was found in four locations at depths ranging from 0.5 to 21 m bgl. An oily sheen was observed in five locations generally occurring around 7 to 12 m bgl. All but two exploratory locations contained sand, gravel or clay that was stained brown or black.

2.7

CONTAMINATION TARGETS

2.7.1

Initial Quantitative Risk Assessment (QRA) was undertaken by WYGE in 2004 and identified potential risks from a range of contaminants to a number of receptors as follows: i.

Human health;

ii.

Surface waters – the River Thames;

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REMEDIAL METHOD STATEMENT iii.

Shallow groundwater in the River Terrace Gravels minor aquifer; and

iv.

Deep groundwater in the lower Lambeth, Thanet and Chalk major aquifer.

2.7.2

More detailed groundwater QRA was then undertaken in 2006 in consultation with the EA and it was agreed that the key receptor considered would be the Thames with the River Terrace Gravels forming the pathway from the site to the Thames.

2.7.3

Key contaminants of concern were identified in the 2006 QRA in unsaturated soils and groundwater and Site Specific Target Levels (SSTLs) were derived as follows for the northwest of the site with the Thames as the key receptor (Remediation Strategy Statement V5 July 07):

Contaminant

SSTL

Arsenic

370 mg/kg

Ortho xylene

61 mg/kg

m-xylene

92 mg/kg

Phenol

15 mg/kg

TPH Aromatics >C8-C10

240 mg/kg

Naphthalene

100 mg/kg

Soil

2.7.4

It is understood that the above criteria were agreed between WYGE and the Environment Agency at the end of 2007. The performance requirements of the remediation do not include groundwater SSTLs; remediation of the aquifer itself is not required.

2.8

SOIL CONTAMINATION

2.8.1

Several stages of intrusive investigation have revealed concentrations of phenol, naphthalene, xylene, arsenic, copper, and TPH aromatics C10-C12 and C12-C16 in excess of the SSTLs set out in the WYGE Specification.

2.8.2

Numerous samples were tested from the unsaturated zone and many locations showed contamination in excess of SSTLs.

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REMEDIAL METHOD STATEMENT SECTION 3

CONTRACT OBJECTIVES & REQUIREMENTS 3.1

3.2

3.3

SECTION 4

The previously issued WYGE Remediation Specification is subject to confirmation. The principal contract objectives within Area 1 and Area 2 are understood to be to: i.

Remediate soils above the minor aquifer water table but including the tidal smear zone,

ii.

Remove contaminated perched water within subsurface features above the Gravels and Alluvium,

Further details of the requirements are: i.

To achieve a significant decrease in non-aqueous phase liquids (NAPL),

ii.

To improve water quality by contaminant source removal,

iii.

To provide for remediation licensing arrangements, monitoring, environmental control and validation.

environmental

The following authorisations have been acquired in order for the remedial works to take place: i.

Trade effluent discharge consent to dispose of liquids to a foul sewer;

ii.

A Section 61 agreement detailing the required noise level limits;

iii.

Planning consent (ref: 07/01493/FUL) prior to the works commencing.

3.4

The site is not located within an installation or site covered by Pollution, Prevention and Control (PPC) permit or a waste management site licence.

3.5

Following further discussion with WYGE it is understood that the recovery of NAPL is to be limited to the recovery of materials exposed by the remedial excavations in and around the tanks and that techniques to recover possible NAPL from within natural strata below the water table are not required.

3.6

For the avoidance of doubt, the works do not include for the provision of any form of in-ground barrier.

REMEDIAL METHOD STATEMENT 4.1

INTRODUCTION

4.1.1

Recognising the principal objectives of the remediation strategy, technical proposals have been assembled which are set out below.

4.1.2

The core design philosophy will be to achieve long term reduction of risk to groundwater and surface water by the removal of the accessible source materials exceeding WYGE’s SSTLs. Further mitigation will be obtained by the proposed

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REMEDIAL METHOD STATEMENT interruption of infiltration, upon construction of the positively drained concrete slabs which are contained within the development proposals. 4.1.3

The proposals are based on a process remediation approach. Frankis holds an Environment Agency Mobile Treatment Licence (MTL) for the process remediation of waste soils and liquids. A Deployment Form (DF) has been submitted to the EA in respect of the proposed works, as required by the MTL regime. This DF was approved by the Environment Agency on 22 January 2008.

4.2

SOLID SOURCE REMEDIATION

4.2.1

Prior to the commencement of remedial works the site establishment will be undertaken including the installation of site offices, welfare, traffic routeing, fencing and wheel cleansing facilities. The ‘clean and dirty’ zone separation will be set up at this stage including access via a decontamination unit. Seven environmental monitoring stations will also be set up at key locations around the perimeter of the site with provision for monitoring of the following:

4.2.2

i.

Settleable dust by dust deposition gauge (DDG);

ii.

Fugitive emissions of benzene and general hydrocarbons, to be assessed by adsorption tube;

The following parameters will also be determined at the monitoring stations by spot readings on a regular programme: i.

general volatile organics by Photo-Ionisation Detector (PID),

ii.

phenols, volatile aromatics, sulphide and ammonia (as necessary) by Draeger tube;

iii.

noise levels;

iv.

airborne asbestos (as required) by pumped air samples examined by phase contrast microscopy.

4.2.3

In addition to the environmental monitoring set out above a programme of surface water sampling and groundwater sampling (using three existing WYGE boreholes) will be undertaken.

4.2.4

Full details of the monitoring programme are set out in Section 5 and Appendix 2.

4.2.5

Following site establishment the site will be cleared of general surface waste and the covering slab will be broken up. The slab will be lifted on a sectional basis so that undue early exposure of fugitive contaminants does not occur.

4.2.6

The contaminated soils at the site will then be subject to excavation and process remediation. It is envisaged that the soils will be treated following the philosophy set out below:

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REMEDIAL METHOD STATEMENT i.

Sorting / segregation of soil arisings as they are excavated to separate the most heavily contaminated fraction which will not be amenable to further remediation (stream A) from potentially suitable or remediable materials (stream B). Disposal of stream A.

ii.

Screening of stream B to recover hard materials (stream C) followed by segregation of the screenings into material potentially suitable for direct backfill (stream D) for validation testing, and recovery of the remainder to covered windrow-biocells for bioremediation / attenuation (stream E).

iii.

Maintenance of degradation promoting conditions in the stream E biocells to achieve the criteria. Any recalcitrant materials not achieving the criteria within acceptable time limits to be disposed.

iv.

Direct recovery of NAPL by either pumping to tank or adsorption onto solid media for excavation and disposal.

v.

Direct recovery of in-ground sub-structures such as slabs, brick walls etc by breaking out and excavation.

vi.

Backfilling of all compliant soils and disposal of any remaining non-compliant soils.

4.2.7

In the absence of firm data on the tidal range of groundwater and effects from Barrier closure, it is proposed that excavations will extend to 0.0 m AOD or to natural ground. Where excavations terminate in natural ground the soils down to but not including 0.0 m AOD will be validated.

4.2.8

Any deficit in backfill will be made up to the underside of the piling platform level with suitable fill material. The piling platform will then be laid to achieve the required finish level for the contract.

4.3

STREAM E – BIOREMEDIATION

4.3.1

It is estimated that one third (approximately 4000 m ) of the excavated material will require treatment by means of bioremediation (Stream E). The material comprising Stream E will be treated in two different ways depending upon olfactory and PID observations:

4.3.2

3

i.

Biopiles;

ii.

Windrows;

The more heavily contaminated material will be subject to placement within biopiles. Within the biopile microbial activity is stimulated through aeration and by the addition of nutrients and moisture. The resulting enhanced microbial activity results in degradation in adsorbed petroleum products thus enabling the treated material to be re-used on site.

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REMEDIAL METHOD STATEMENT 4.3.3

Windrows will be used to treat the lesser contaminated section of Stream E material. The material will be spread onto a prepared hardstanding into windrows which provide a high surface area to stimulate microbial action. Regular movement of the material comprising the windrows exposes further contaminated soil to the atmosphere which accelerates the microbial degradation of the contaminants. In order to minimise nuisance vapours the windrows will be covered between turning operations.

4.3.4

The following parameters will determine the optimal effectiveness of the biopiles/windrows: i.

Soil pH to be within the 6 – 8 range;

ii.

Moisture content of the soil to be 45-80% of the water holding capacity;

iii.

Soil temperature to be within the range 10-45 °C;

iv.

Nutrient concentrations to be within the carbon: nitrogen: phosphorous ratio of 100: 10: 1 to 100: 1: 0.5;

v.

Soil texture to be blended so as not to be too clay-like as this makes aeration of the material more onerous.

4.3.5

The biopile will be covered in a protective fleece and air will be extracted from the material by means of perforated pipework within the biopile. A water/nutrient supply tank will be connected to the biopile in order to maintain optimum conditions for microbial degradation within the material to be treated. Attached to the extracting air pump will be an air/water separator and a filter to capture any volatile emissions that are released from the biopile. The biopile itself is independently bunded and constructed upon an area of hardstanding with an incline falling to a sump in order to collect any leachate or surface water run-off from within the treatment area.

4.3.6

The treatment area for the biopiles is expected to be around 2500 m and each batch of material to be treated will take between 12 – 20 weeks to treat.

4.3.7

Any material not reaching the required Site Specific Target Levels (SSTLs) will be quarantined and characterised for off-site disposal.

4.4

WASTEWATER HANDLING

4.4.1

The soil remediation will encounter bodies of perched water within the fill materials and caught within relic structures. These waters will be recovered by pumping and processed through a water treatment system (WTS) prior to discharge to foul sewer. The treatment system will comprise: sediment trap, oil/water separator, air stripping tower and granular activated carbon cartridge. The discharge to foul manhole will be metered and licensed.

2

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REMEDIAL METHOD STATEMENT 4.4.2

Any areas of deep excavation which provide exposure of the water table will also facilitate the recovery of floating product (LNAPL) encountered on the water table, which will be recovered by pumping or by oil adsorbent pads.

4.4.3

It is noted that the groundwater at this site is tidal and that while groundwater flows are expected to approach the barrier from the north based on the anticipated regional flow direction in the Gravels, the flow direction is expected to be reversed at certain states of the tide.

4.5

WASTE TYPES AND QUANTITIES

4.5.1

The following table lists the waste types and quantities including the six-digit code from the European Waste Catalogue (EWC) that will be treated at the operating site: 3

Waste type

EWC six-digit code

Quantity (m )

Soil and stones containing dangerous substances Oil wastes not otherwise specified Sludges from groundwater remediation containing dangerous substances (Carbon cartridges)

17.05.03

12000

Medium (solid, water, sludge, gas) Solid

13.08.99

10

Sludge

19.13.05

5

Sludge

3

4.5.2

Of the total waste soil quantity, 8000 m is expected to be suitable for 3 segregation/bioremediation and 4000 m will be suitable for physical processing.

4.6

ACCEPTANCE PROCEDURES

4.6.1

Material proposed for remedial treatment will be selected at source and delivered into the treatment area by dumper lorry.

4.6.2

Upon entry to the treatment area there will be a visual inspection of the material to be treated prior to off-loading. If the material is found to be unsuitable then the material will be placed within the quarantine area.

4.6.3

If unsuitable material is found within a tipped load then it will be moved by machine to the quarantine area.

4.6.4

Material in the quarantine area will be sampled for characterisation and disposal.

4.6.5

The maximum time that unsuitable material can be stored in the quarantine area is one month. This will allow time for the relevant analysis and for the subsequent

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REMEDIAL METHOD STATEMENT landfill location to be identified. If the material is required to stay in the quarantine area for longer then approval will be sought from the Environment Agency.

SECTION 5

4.7

QUARANTINE AREAS

4.7.1

It is anticipated that the throughput of the complex sorting process is to be 500 m per day. A maximum quarantine storage capacity of three days’ throughput (i.e. 3 1500 m ) will be provided within the sorting facility. The quarantine area can be seen on the Site Plan (reference: S3707-303-001-A1) included in Appendix 1.

4.8

COMMISSIONING, OPERATION AND MAINTENANCE

4.8.1

Prior to any treatment of soils excavated there will be a period of time devoted to breaking out the significant concrete hard-standing on the surface of the area to be remediated.

4.8.2

After the initial enabling works to break out the concrete hard-standing, the first week of soil treatment operations will be treated as a validation period. During this time records of air emissions will be noted and compared with the data collected during the baseline monitoring period.

4.8.3

If any monitoring control level or licence condition is breached during this period then the methods employed for the treatment process will be revised.

4.8.4

Upon completion of the commissioning a validation report will be provided to the Environment Agency.

3

ENVIRONMENTAL MONITORING AND AUDIT 5.1

INTRODUCTION

5.1.1

Merebrook will be retained to record and validate the remedial works and associated monitoring. A Merebrook engineer will provide full time assistance during the main excavation works and part time assistance in periods of lower activity during the bio-remediation.

5.2

MONITORING

5.2.1

A monitoring program will be adhered to throughout the works in order to prevent any harmful effects to the identified primary receptors surrounding the site. These primary receptors are as follows: i.

Local businesses and employees, local housing and residents immediately to the east of the site including the Tradewinds site.

ii.

Users of Pontoon Dock DLR station immediately to the west of the site;

iii.

Thames Barrier Park immediately to the south-west of the site;

iv.

Site employees and visitors;

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REMEDIAL METHOD STATEMENT

5.2.2

v.

Shallow groundwater contained in the River Terrace Deposits;

vi.

River Thames;

vii.

Local flora and fauna (protected beetles within the construction zone if still present).

Seven Monitoring Points (MP) have been assigned to the perimeter of the site in order to monitor any fugitive emissions of dust, odours, noise, airborne contaminants and VOCs from the remediation works. Each MP is sympathetic to the above receptors as described below: i.

MP1 – Adjacent to the north-west of the Tradewinds residential development;

ii.

MP2 – Adjacent to the south-west of the Tradewinds residential development;

iii.

MP3 – Adjacent to the east of Thames Barrier Park (in line with the children’s play area);

iv.

MP4 – Adjacent to the north of Thames Barrier Park;

v.

MP5 – Adjacent to the east of the Pontoon Dock DLR car park;

vi.

MP6 – Adjacent to the north of the Tradewinds residential development opposite the proposed site entrance;

vii.

MP7 – Adjacent to the North Woolwich Road at the north of the site.

5.2.3

A site induction and appropriate Personal Protective Equipment (PPE) will be mandatory with respect to the health and safety of site visitors and employees.

5.2.4

Groundwater will be monitored up-gradient and down gradient towards the River Thames at three locations as listed below: i.

GW1 & GW2 – Down-gradient sentinel groundwater monitoring points (WYGE: BH420 and BH419) towards the south of the site designed to monitor potential contamination into shallow groundwater and the River Thames;

ii.

GW3 – Up-gradient groundwater monitoring point towards the north of the site (WYGE: BH410).

5.2.5

VOC monitoring will also be undertaken when required at the excavation face, stockpiles or around the perimeter of the site.

5.2.6

The locations of the MPs can be seen on the Site Plan (Reference: S3707-303001-A2) which is included in Appendix 1 of this report.

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REMEDIAL METHOD STATEMENT 5.3

BASELINE MONITORING

5.3.1

Baseline monitoring data for groundwater and soil gas has effectively been collected throughout the Phase 2 Site Investigation carried out by WYGE. At least one additional round of groundwater monitoring will be carried out prior to the remedial works taking place in order to assess the most recent groundwater conditions associated with the operating site.

5.3.2

The Environment Agency Groundwater Protection Team do not require surface water monitoring during the works, therefore there will be no baseline monitoring of surface water features (i.e. The River Thames)

5.3.3

In the case of emissions to air the following baseline monitoring measures are proposed to take place at the ordained Monitoring Points at least two week’s prior to the commencement of the remediation works: i.

Installation of passive Dust Deposition Gauges (DDGs)

ii.

Implementation of Adsorption Tubes for Phenols, Benzene and general Hydrocarbons.

iii.

Three rounds of PID monitoring to cover the entire site boundary.

5.3.4

Details of the monitoring limits, protocol and frequencies for each medium are described in the Monitoring Plan (Reference: MP-S3707-07-147) included in Appendix 2 of this report.

5.4

POLLUTION CONTROL – DUSTS, FIBRES, PARTICULATES, VAPOURS, GASES, AEROSOLS AND ODOURS

5.4.1

The abatement of dust generated during the remediation works will be achieved by the damping of soil by water spray to the stockpiles of material to be treated. Roadways within the site will be kept moist by water bowser. Additionally, the drop distance from excavator bucket to stockpile/process plant will be kept as short as reasonably practicable.

5.4.2

Dust will be monitored using Dust Deposition Gauges (DDG). One DDG will be installed on each boundary of the operating site. The collection bottle at the bottom of the DDG will be changed on a weekly basis in order to assess the daily deposition rate. A guidance dust level of 150 mg/m2/day will be applied. This is the level at which complaints may start to occur, as set out in research by Vallack and Shillito (1998): Suggested Guidelines for Deposited Ambient Dust.

5.4.3

In the event that the value of 150 mg/m2/day is exceeded then greater efforts will be made to keep dust levels to a minimum. These will include: i.

Increased spraying down of airborne dust;

ii.

Review of house-keeping methods and work practices;

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REMEDIAL METHOD STATEMENT iii.

Site manager to enforce dust abatement measures more rigorously and ensure operatives within the site take heed.

5.4.4

The dust monitoring points will be protected by Heras fencing.

5.4.5

The monitoring locations have been chosen to cover all wind directions within the sorting facility relevant to sensitive receptors.

5.5

ASBESTOS

5.5.1

It is possible during the works that Asbestos Containing Materials (ACMs)will be recovered from the excavation face

5.5.2

Key operatives within Frankis will be provided with an asbestos awareness course prior to commencing works in the treatment area covered in this Deployment Form.

5.5.3

If suspected ACMs are visually identified at the excavation face then works will be halted. The following procedures will be then be followed: i.

The site foreman will be informed;

ii.

The material will be carefully excavated under a fine mist of water spray to minimise any asbestos fibres becoming airborne;

iii.

The material will then be placed in quarantine awaiting disposal or handpicking whichever is deemed appropriate;

iv.

If this material is to be hand-picked then any resulting asbestos waste will be double bagged in red and clear asbestos bags and place in an area secured by Heras fencing to await removal from site by a specialist contractor.

v.

Once the material has been hand-picked, one sample per 250 m3 will be taken to ascertain whether it is suitable for potential re-use on the site or for further processing.

5.5.4

Should any asbestos be visually identified within the soil brought into the treatment area then works will be halted and the site foreman shall be informed. Steps ii-v of Section 5.5.3 will then be followed.

5.5.5

Air monitoring for asbestos fibres will be carried out by an independent UKAS accredited analytical (company) in the case of any suspected ACMs excavated at the site. If the results of the air monitoring exceed 0.01 fibres per millilitre of air then the practices for dealing with asbestos will be reviewed and adapted in order to achieve results below this concentration.

5.6

RADIATION

5.6.1

It is not thought that radiation pollution control is required on this remediation project as radioactive materials have not been prioritised as contaminants of concern.

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THAMES BARRIER PARK EAST, SILVERTOWN

REMEDIAL METHOD STATEMENT 5.7

ODOURS

5.7.1

Odours will be assessed on an olfactory basis by twice daily inspections of all site boundaries. Where any potential nuisance odours are detected abatement measures will be applied. Measures to control odours will include: i.

The spraying of odorous stockpiles with an approved odour suppressant (e.g. BAT 505) ;

ii.

The covering of odorous stockpile materials with plastic sheeting;

iii.

In extreme cases it may be necessary for a continuous odour suppressant to be used around the borders of the sorting facility upwind of the offending odour.

5.8

VOC EMISSIONS

5.8.1

VOC emissions will be monitored using a Photo-Ionisation Detector (PID). The PID will be used periodically throughout the working day (minimum twice daily) around the boundaries of the sorting facility and adjacent to any excavations or stockpiles suspected of emitting VOC vapours. i.

Should the PID detect any values in excess of 10 ppm then conditions will be reviewed and abatement measures will be applied if readings do not fall back to background levels within 1 hour.

ii.

Works will automatically be abated if sustained readings of 50 ppm are observed.

5.8.2

The above control limits are derived from HSE document: EH40 Annual Workplace Exposure Limits. 10 ppm was selected as the initial warning level as this is the Workplace Exposure Limit (WEL) for suspected VOCs such as toluene over an eight-hour period time weighted average (TWA). An automatic abatement level of 50 ppm was selected as this is the WEL for suspected VOCs such as xylene over an eight-hour period TWA. 50 ppm is also a good indicator of VOC levels where odour may become an issue.

5.8.3

VOC abatement will take the form of covering stockpiles with non-VOC contaminated soil or plastic sheeting or the application of VOC suppressant spray.

5.9

CONTROL OF NOISE

5.9.1

Throughout the remedial works at the operating site, measures will be implemented and maintained to control noise emissions.

5.9.2

Baseline noise monitoring will take place at least one week prior to any works carried out on the site.

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THAMES BARRIER PARK EAST, SILVERTOWN

REMEDIAL METHOD STATEMENT

SECTION 6

5.9.3

The site layout will ensure that, where possible, the activities that will cause the greatest noise emissions will be situated as far as possible from residential and recreational areas (i.e. Tradewinds and Thames Barrier Park).

5.9.4

To minimise noise at the site all loading/unloading and remedial processes will be carried out utilising low intensity works where possible. Normal operational work hours will be 0800hrs until 1800hrs Monday to Friday, and 0800hrs to 1300hrs on Saturdays.

5.9.5

Site workers will be provided with suitable PPE.

5.9.6

Trigger levels for noise are set in compliance with The Control of Noise at Work Regulations 2005 (the Noise Regulations) that came into force on 6 April 2006. These are: i.

The level at which employers must provide hearing protection and hearing protections zones is 85 decibels (db);

ii.

The level at which employers must assess the risk to workers health is 80db.

iii.

Noise will be monitored within the work area using a hand-held calibrated sound meter and the average and peak level recorded.

5.9.7

All plant will be operated in accordance with manufacturers instructions to minimise noise generation and ear protection will be worn in accordance with the machinery operating instructions.

5.9.8

With regard to contributing to environmental noise outside the site, Frankis will work for compliance with the noise limit set by the London Borough of Newham under a Section 61 Notice made under the Control of Pollution Act 1974.

5.9.9

The environmental noise thresholds limits enforced by the Section 61 notice are: i.

Equivalent Sound Pressure Level (LA Eq 1 hour) = 75 db

ii.

Instantaneous Sound Pressure Level (LA 10) = 85 db

iii.

Further details of the monitoring of noise can be found in the monitoring plan contained within Appendix 2.

VALIDATION 6.1

Upon completion of the works a validation report will be produced providing an account of the works carried out, the findings of the associated validation testing and the conclusions from the environmental monitoring.

6.2

Validation will be accomplished by sampling the excavated areas at the following frequencies: i.

One sample per 100 m base;

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2

(10 x 10 m sampling grid) within the excavation

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THAMES BARRIER PARK EAST, SILVERTOWN

REMEDIAL METHOD STATEMENT ii.

2

One sample per 20 m (10 x 2 m sampling grid) at the sides of the excavated areas.

6.3

The stockpiles of treated material will be subjected to a validation sampling regime 3 of one sample per 100 m of treated material.

6.4

Each sample location will be recorded on a plan of the site.

6.5

The validation samples will be analysed for metals, pH, EC, BTEX, petroleum hydrocarbons, EPA 16 PAH, speciated phenols and compared against the QRA SSTLs.

6.6

Should a validation sample from the excavation fail to meet the SSTLs then further excavation of material will be actioned until such time as all visual and olfactory evidence of contamination has been removed and further validation samples will be taken.

6.7

In the case of the failure of validation sampling within the stockpiles of treated material then further treatment will be applied in the first instance. Should any material continue to fail the required SSTLs then the material will be classified for off-site disposal.

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THAMES BARRIER PARK EAST, SILVERTOWN

REMEDIAL METHOD STATEMENT

APPENDIX 1




Site Plan (Reference S3707-303-001-A2)

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THAMES BARRIER PARK EAST, SILVERTOWN

REMEDIAL METHOD STATEMENT

APPENDIX 2




Monitoring Plan (Reference: MP-S3707-07-147)

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Reference : RMS-S3707-08-14, January 2008