Lowering the Carbon Footprint of Thermal Remediation Systems

The business of sustainability

Lowering the Carbon Footprint of Thermal Remediation SystemsJames Baldock, Jen Brett, Simon Tillotson and Jay Dablow


© Copyright 2017 by ERM Worldwide

Group Limited and/or its affiliates

(‘ERM’). All Rights Reserved. No part

of this work may be reproduced or

transmitted in any form or by any

means, without prior written

permission of ERM.


Carbon Footprint Reduction: Approach

PLANNING

(brownfield)REMEDIATION

CONSTRUCTION

PROJECT

DEFINITIONRISK

ASSESSMENT

REMEDIAL

OPTIONS

APPRAISAL

SITE

INVESTIGATION

REMEDIATION

OPTIMISATION

Green Remediation

CLIENT

OBJECTIVE

CLIENT

GOAL

Community & stakeholder engagement

Sustainable Procurement

Setting the remediation

specification and strategy

Setting the remediation

technical approach

ERM has integrated consideration of sustainability with key stages in project delivery

■ Remedial Options Appraisal

■ Multi Criteria Analysis

■ Remedial Design

■ Thermal Modelling

■ Equipment Design

■ BMPs

■ Remedial Optimisation

■ Temperature Tracking

■ Low Temperature Volatilisation (LTV)

■ Post Thermal Biodegradation

2


Background

■ ERM designed an In-Situ Thermal

Desorption (ISTD) system

■ Implemented inside a building, at an

operational manufacturing site in the

UK

■ Long manufacturing history

■ The system was implemented following

10 years of unsuccessful operation of a

pump and treat system

■ Organic compounds mainly kerosene

and chlorobenzene. Also localised

TCE & methylene chloride. All at

concentrations >100mg/l

■ Method based approach agreed with

regulatory authorities

3


Geology, Hydrogeology, Hydrology

4

Chalk

Clays, Silts, Sands

Chalk (Saline Intrusion)

Groundwater Flow

Receptor: Channels


System Installation

5


Completed Well Field

6


Vapour / Liquid Phase Treatment Systems

7

Vapour Phase GACS and Vent Stack

Condensate to Liquid Phase Treatment

Heat Exchanger

Blower Units

One Liquid Phase GACOil / Water Separator & Silt Trap

Vapour Treatment Phase

To Effluent Discharge Point


Remedial Options Appraisal


Multi Criteria Analysis (MCA) Methodology

9

First MCA exercise is to weight the importance of the different metrics in this specific circumstance.

Input from other stakeholders is very instructive – shows what is important to them

Currently, the most important factors (i.e. with biggest weight) are:

■ impact on water and air

■ natural resource use and waste

■ human health and safety

■ compliance with regulators

■ legacy and project risk

Sustainability criteria

Environment

Weight

(1-5) Justification of Weighting and Comments

Impact on water 5 pollutant linkage is through water

Impact on soil 1 soil impact is not the driver of risk

Impact on air 5 GHG emissions primary metric

Impact on ecology 3 eco-receptor is one of two drivers

Natural resource use and waste generation 4 magnitude of Corp Environmental Policy on CO2

Intrusiveness 3 impacts on site management and personnel

Social

Human health 5 critical concern to site and ERM

Safety 5 critical concern to site and ERM

Ethical and equity considerations 1 ‘do nothing’ would be poor corporate care

Policy and legislative compliance 5 Regulators have requested action on source area

Impact on surroundings 2 will be on a visible part of site

Uncertainty, evidence and verification 1 not critical consideration, effort driven

Community involvement & satisfaction 3 Local Authority and neighbouring amenity concerns

Economic

Direct costs 3 to be confirmed by Corporate EHS

Indirect costs 3 costs due to partial site access closure, and vibrations may slow site works

Legacy and projects risks 5 Corporate concerns driving the project


Sustainability criteria

Do

nothing Excavation

MPE Three

years Thermal MPE 6 months

Weighting

Environment (1-5)

Impact on water 5 -2 5 2 4 1

Impact on soil 1 -2 5 1 4 0

Impact on air 5 -1 -2 -3 -4 -1

Impact on ecology 3 -2 5 1 4 0

Natural resource use and waste generation 4 0 -1 -2 -3 -1

Intrusiveness 3 0 -5 -3 -1 -1

Social

Human health 5 0 -1 0 0 0

Safety 5 0 -4 -2 0 -1

Ethical and equity considerations 1 -2 0 0 0 0

Policy and legislative compliance 5 -2 4 2 4 1

Impact on surroundings 2 0 -2 0 1 1

Uncertainty, evidence and verification 1 0 3 0 0 0

Community involvement & satisfaction 3 -2 -4 0 0 0

Economic

Direct costs 3 5 -3 -2 -3 -1

Indirect costs 3 0 -3 0 0 0

Employment opportunities & human capital 1 0 0 0 0 0

Gearing 1 0 0 0 0 0

Legacy and projects risks 5 -2 5 1 4 1

Flexibility 1 0 0 0 0 0

Net environmental benefit -23 16 -18 1 -7

Net social benefit -18 -18 0 22 2

Net economic benefit 5 7 -1 11 2

Overall net-benefit (Sustainability) -36 5 -19 34 -3

RANK 5 2 4 1 3

MCA Results

10


MCA Conclusions

11

Thermally enhanced DPVE (using conductive heating) was

the preference for the following reasons:

■ Health & safety and logistical challenges of soil excavation alternative:

Social factors dominant

■ High probability of success compared to all other in-situ techniques.

■ A higher maximum technically-achievable mass removal compared to

other in-situ techniques

■ The only in-situ technique that can realistically reduce the residual

DNAPL contaminant mass (thought to be the majority) within relatively

low permeability strata


Remedial Design


Thermal Modelling

13

■ A thermal model using Petrasim PC

based software was carried out to:

■ Evaluate heating methodology and

associated heat energy

consumption;

■ Predict heating duration;

■ Determine the optimum well

spacing to achieve the Target

Treatment Temperature (TTT) in

the most energy efficient manner

100 m60 m

24.38m

Pilot

Test –

Initial

Model

Dimen

sions

CHAL

K

SILT

CLAY

FILL

Y =

5mX =

5m

0.0 -

0.2m0.2 -

1.0m

1.0 -

3.0m

3.0 -

3.2m

3.2 -

5.5m

5.5 -

8.0m


Model Results

14

A variety of well configurations were modelled

The optimum configuration showed that significant contaminant reduction was predicted to occur

with 3.0m well spacing after 120 days of heating (co-boiling point of kerosene and water)


Equipment Design

15

■ Sustainable procurement:

Both gas and electric ISTD

options considered – gas

has a lower carbon footprint

and cost in the UK so was

selected (not the case

everywhere!)

■ Process engineering: heat

exchangers added to

minimise carbon use

■ Real time monitoring:

automated temperature

collection data using

thermocouples


Best Management Practises

16

BMP

Assure suitable sizing of in-well heating units, to optimize energy use

Include feedback loops in the process control system, to allow precise application of heat and the desired temperature and duration

Explore the use of natural gas-fired systems that enable in-well combustion of the contaminants and recovery of associated heat, resulting in lower energy demand

Increase automation through use of equipment such as electronic pressure transducers and thermo-couples with an automatic data logger (rather than manual readings) to record data at frequent intervals

Monitor soil temperatures on a regular basis to assure uniform heating in target areas and avoid unexpected heating and energy waste in non-targeted areas

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Remedial Optimisation


Temperature Tracking

18


Low Temperature Volatilization (LTV)

19

■ Initial target temperature based on traditional volatilization

■ LTV Concept:

■ Groundwater contains dissolved gases

■ During in situ heating, chemical and biochemical reactions occur that

increase the concentrations/partial pressures of the dissolved gases

■ CO2 generated and released can also remove VOC contamination

■ At this site lowered treatment temperatures from ~150˚C to an

average of 80ºC (heating time 80 days compared to the 120

modelled)

■ Benefits: lower energy use, carbon footprint, cost and time to

complete


Mass Recovery

20

Heating off

Estimated mass of 380kg

recovered

Circa 70% decrease in

groundwater dissolved phase

concentrations


0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0

50

100

150

200

250

300

350

05/06/15 25/06/15 15/07/15 04/08/15 24/08/15 13/09/15 03/10/15 23/10/15 12/11/15

CO

2 (

%)

PID

(p

pm

(V))

Date PID Concentration CO2 Concentration

VOC and CO2 Concentrations Over Time

21

Heating off


Carbon Footprint (kg CO2 eq)

22

75000

85000

95000

105000

115000

125000

135000

145000

LTV Conventional

Using LTV reduced CO2

consumption by 16%


Post Thermal Biodegradation

23

1

10

100

1000

10000

100000

1000000

10000000

DP003 DP013 DP020

Before

After


Summary


Summary

■ Thermal projects are energy intensive, but rapidly completed, meaning

overall energy consumption may be lower than expected

■ If a thermal remedy is selected a combination of sustainable design and

implementation can reduce CO2 footprint

■ Target temperature was significantly lower than initially expected using

the LTV approach in combination with real time monitoring, leading to

CO2 reductions

■ LTV:

■ 10% reduction in both time and costs to be realised (heating

equipment removed from site earlier)

■ CO2 consumption reduced by circa 16%

■ Longer term biodegradation can be successfully applied post thermal

■ Endpoints achieved and the project was ‘closed’

25


26

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Lowering the Carbon Footprint of Thermal Remediation Systems

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