HS2 CAMDEN DEMOLITION AND DUST PROCESS REVIEW...Peer Review C&D Demolition Consultants Ltd were invited to attend a peer review at the Regents Park Estate on Thursday the 16th of January

HS2 – CAMDEN

DEMOLITION AND DUST

PROCESS REVIEW

Report Number: HS2-CAM-01 Author: MIDE AssocRICS MIIRSM GradIOSH AIExpE

C&D Demolition Consultants Ltd

Egerton House

2 Tower Road, Birkenhead

CH41 1FN

0151 305 0909

[email protected]

www.canddconsultants.co.uk

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Table of Contents C&D Demolition Consultants Ltd ................................................................ 3

The Brief ..................................................................................................... 3

Peer Review ............................................................................................... 4

Demolition Methodology ............................................................................. 4

Dust Curtain ............................................................................................... 6

Dust Suppression ....................................................................................... 7

Additional Dust Suppression ...................................................................... 9

Peer Review and Demolition Engineers advice ........................................ 11

Methodology ............................................................................................. 12

Conclusion ............................................................................................... 13

Appendix 1 – Table of material reviewed ................................................... 16


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C&D Demolition Consultants Ltd

C&D is one of the UK’s leading ‘award-winning’ demolition and asbestos consultants and has

been involved in over 400 complex projects worldwide, ranging from the explosive demolition

of 30-storey tower blocks, tower block by top down and high reach demolition to industrial

demolition, inner city demolition and oil rig offshore work.

We are full members of the Institute of Demolition Engineers (IDE), Institute of Occupational

Safety and Health (IOSH), International Institute of Risk and Safety Management (IIRSM),

European Federation of Explosive Engineers, ARCA Asbestos Managers and Chartered

Structural Engineers.

C&D Demolition Consultants Ltd helped to implement BS:6187-2011, which is the code of

practice for full and partial demolition. We aim to help clients understand the management of

the demolition process for structural stability using temporary works where required. C&D

also have two engineers who are on the first ever Demolition Engineering MSc degree.

The Brief

C&D Demolition Consultants Ltd were appointed by of Costain Skanska joint

venture and requested C&D to carry out the peer review on behalf of HS2. C&D were asked

to give their expert opinion on the demolition contract that is being undertaken by Clifford

Devlin Ltd in Camden.

They have asked C&D to produce a written report and comment on how the demolition is

being carried out. In addition to reviewing the dust process. C&D will refer to the following

legislation that is legally binding for this contract. This namely being the CDM (Construction,

Design and Management) 2015 Regulations, BS:6187-2011, (Demolition Code of Practice)

Control of Asbestos Regulations 2012 and NFDC Code of Practice for High Reach demolition

rigs and exclusion zones.

The joint venture has asked for two specifics in relation to the demolition to be highlighted

and reported on in this report.

1- Is the demolition using a high reach and associated dust curtain compliant with current

demolition legislation?

2- Is the dust suppression being used at the site compliant and best practice?


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Peer Review

C&D Demolition Consultants Ltd were invited to attend a peer review at the Regents Park

Estate on Thursday the 16th of January 2020 at 14.30 hours. The meeting consisted of the

delivery team from the HS2 joint venture and two members of the Camden Council delivery

team in relation to HS2. Following a presentation from the joint venture, plus reviewing the

documentation in relation to the demolition. The joint venture confirmed that I was to carry out

a report on my findings as stated in the brief.

Demolition Methodology

Following my visit and subsequent review of previous demolition methodologies employed on

site it was clear that they had previously used a high reach excavator and a demolition

curtain attached to a mobile crane. This had worked well in terms of demolition and no

materials exited the site or was considered a danger to the onsite operatives or to the nearby

residents.

The use of a high reach excavator is a method, were it reduces the need for scaffolding to be

erected around the building and being brought down on a floor by floor basis. However, to be

successful there does need to be an area where the materials can fall safely within an

exclusion zone or can be shielded as per the curtain attached to a mobile crane. This

technique is commonly used within the industry and is heavily documented in BS:6187-2011

code of practice for demolition. In addition, The National Federation of Demolition Contractors

(NFDC) have produced specific guidance notes for using a high reach excavator. Further

guidance can be found by the European Demolition Association (EDA) technical commission

who have released high reach guidance notes. Having had time to review the high reach

being employed by Clifford Devlin the demolition contractor, is compliant and conforms with

all UK legislation and as well as European guidance notes by the EDA.

Figure 1- BS:6187-2011 - Code of Practice for full and partial demolition


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Figure 2- European Demolition Association high reach demolition notes

Figure 3- NFDC Demolition Exclusion zone guidance notes

Figure 4 - NFDC Demolition high reach guidance notes


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Figure 5- institute of Air quality management assessment of dust from demolition and construction

The exclusion zone from demolition area to fence line is 11m with a substantial timber

hoarding surrounding the site at 2.4m high. On reviewing the NFDC guidance notes for

exclusion zones this is compliant with the guidance notes and the exclusion zone has been

reviewed by the demolition contractor and the joint venture.

Dust Curtain

The use of dust curtains is now becoming main stream in the demolition industry as a means

to maintain materials staying within the footprint of the demolition area when they are being

demolished by use of high reach excavator. It prevents scaffolding being erected around the

building and associated sheeting being installed. This can be a time-consuming operation to

erect the scaffolding and puts in place hundreds of man hours of working at height. The most

common method of dust curtains is generally fabricated from conveyor belt which have been

fabricated together to form a strong bond. Tested steel beams are used at the top and bottom

of the curtain so at the top the crane has a level lifting point and at the bottom the curtain is

weighted to prevent debris ejecting from the existing site. This procedure is common

throughout the demolition industry and throughout the European demolition industry. For

contracts like Regents Park Estate it is a technique for buildings that are straight forward to

demolish and the use of scaffolding is not viable in terms of cost and more importantly safety.

Falling from height is the biggest killer in the construction industry and under the CDM 2015

regulations the principle of elimination should be deemed paramount. Therefore, scaffolding

should be avoided where possible on all construction projects. Also, under the 2005 working

at height regulations it clearly states to avoid where possible the need to work at height. The

use of the high reach and dust curtain elimated operatives working at height alongside

scaffolding operatives. A traditional top down demolition could have up to 7-8 operatives

working at height alongside scaffolding operatives. The high reach completely eradicates this

operation preventing no risk to demolition or scaffolding operatives. The slight uplift in dust

release which is this case has been heavily controlled and mitigated. Is countered by the

reduction of any operatives being placed in danger.


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Figure 6 - Example of a dust curtain being used on a high reach demolition contract

Dust Suppression

Following the peer review it become abundantly clear that the issue of dust had become

paramount for all parties due to the close proximity of tenants living adjacent to the demolition

area. We were asked to review the techniques currently employed and to add any further

advice that we felt we could input to ensure dust was mitigated to its minimal levels.

The current demolition industry are striding to produce best practice following legislation and

requirements noted in the following:

1- Section 80 and section 81 which are demolition notifications and requirements

required by Camden council.

2- BS:6187-2011 Code of practice for demolition section 12.3.9.4

3- Institute of Air Quality Management – Guidance for dust and control on demolition

sites Section 8.1 & 8.2

4- Environmental pollution act 1990 – Part III Statutory nuisances and clean air

5- Section 60 and 61 which is conditions of working on site under agreed limits and

limitations in terms of dust by Camden council

6- The Control of pollution act 1974

On reviewing the demolition Clifford Devlin Ltd had employed several tried and tested

techniques which are mentioned in BS:6187-2011 and the guidance notes for high reach

demolition. The techniques that they were undertaking were as follows:

Waterjets directly fed to the attachment of the high reach excavator. This water is pumped

along the arm of the high reach and forms two water jets at either side of the attachment

spraying high pressure water onto the work area being demolished. This is a new and

modern water suppression technique for high reach excavators and is certainly effective at

combatting dust at high levels. On reviewing the paperwork I can confirm that this method

was being undertaken during the demolition.


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Figure 7- Example of a waterjet direct feed to high reach's attachment

Dust boss – the use of water dust bosses in the demolition industry had become mainstream

following a need to eliminate dust on demolition sites. Section 81, section 60 and the need to

find the best dust suppression ensured the demolition industry had undertaken stringent

strides to reduce dust. The dust boss fires a jet of water in droplet form and the droplets

encapsulate dust particles from the demolition area. These particles of dust once

encapsulated by water are forced to the ground and prevent dust spread. This technique is

extremely successful on large demolition sites. On reviewing the methodology I can confirm

the dust boss was being employed during the demolition.

Figure 8- Example of a dust boss

Moto fogs – One of the criticisms of the dust boss was that it produced large amounts of

water and encapsulated the dust in such a way that occasionally water and dust would exit

the confines of the demolition site. To combat this and to give a finer spray and greater dust

encapsulation moto fogs entered the demolition market. They produce a finer spray and they

can also be more accurate in terms of specific areas covered. The moto fog can also be used


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to produce a fine mist layer that can be helpful in preventing dust spread. Moto fogs are one

of the most up to date dust suppression techniques in the UK today and on reviewing the

paperwork submitted by Clifford Devlin. I can confirm that several of these units were being

used during the demolition. It was clear following my review of the paperwork submitted that

the joint venture had put in mitigating procedures to prevent where possible the release of

dust into the local areas. They had put in place an air quality management plan and ensured

that the air monitors were set to 60 minute trigger times and also that there were six monitors

located around the exterior of the site. They had also ensured that the demolition contractor

had put dust mitigating strategy in place i.e. water jets with the attachment, dust bosses and

moto fogs.

Figure 9- Example of a moto fog working

The demolition curtain that is attached to the mobile crane is to prevent debris exiting the site

to the exclusion zone or the fence boundary. To further mitigate dust Clifford Devlin had

rigged a water suppression unit to the top of the curtain and fixed a water hose to specific

holes creating a further dust suppression at source. I can confirm that I have only seen this in

operation very few times in both the UK and Europe. This is a further and extremely

compliant dust suppression control measure.

Additional Dust Suppression

Following the review on the 5th of December 2019 where several trigger levels had been

exceeded as well as dust levels rising towards current ambient levels. Following a review the

joint venture and Clifford Devlin had adopted a further suppression technique of a high

pressured hose which we commonly see being used by the fire brigade being directed at the


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source of the demolition, with an operative working from a MEWP. This operative will be

working from the MEWP and will guide the water directly onto the area were the demolition is

being undertaken. This additional technique that was introduced after the 5th of December

had the desired affect that no further spikes had occurred from the dust monitoring once this

fifth dust suppression technique was introduced. The Institute of Air Quality Management

produced guidance on monitoring in the vicinity of demolition and construction sites where

they also endorsed the use of direct spraying of water from hand-held devices onto the

demolition area. Following the 2014 guidance on dust and demolition version 1.1, it is clear

that the joint venture and Clifford Devlin have not only complied with current legislation but

are exceeding what could be described as best practice. Once the operation to suppress the

dust from the operative working from a MEWP was undertaken. It gave five direct sources of

water suppression. On reviewing the recorded dust information it was clear that no further

levels were exceeded.

It was clear following my site visit that the demolition was compliant with BS:6187-2011 in

relation to high reach demolition. It was also compliant with the NFDC guidance notes on

high reach demolition. Under CDM 2015 section 20 is specific methodology needed to be in

placed identifying the activities of the high reach excavator plus any dust mitigation. It was

clear from the dust mitigation that not only have they exceed BS:6187-2011 and also the

recommendations in the IQA air quality management, that Clifford Devlin were practicing

beyond current best practices. Whilst on site I witnessed the dust mitigation being carried out

and reviewed the dust monitors to ensure they were not exceeding current levels. During my

visit it was pointed out that the dust monitors were on a 15 minute trigger time as opposed to

industry practice which is normally an hour.

Figure 10- Handheld demolition at ground level


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Peer Review and Demolition Engineers advice

During the discussions of the peer review we were also asked if there were any further

mitigating dust suppression techniques that could be employed. On reviewing the UK and

worldwide demolition industry there is very little further dust suppression techniques that

could be further employed on this site. However, we have suggested some further sensible

and tried and tested recommendations that should ensure dust is kept to beyond reasonably

practicable bearing in mind that there are residents living close to the demolition operation.

1- We have suggested to Clifford Devlin Ltd to employ a further operative working from a

MEWP with a high pressure hose being directed not only at the work area but also at the

floor level were the materials will fall from height to ground floor level. Focusing a jet of

water at the ground floor level will prevent a dust vortex occurring and spreading to the

local properties. During my discussions Clifford Devlin had put in place this method of

dust suppression and once the demolition recommences, they will have two water jets

working on the building being demolished.

Figure 11- Operative working from a cherry picker with a handheld suppression unit

2- One of the areas were dust does occur is at the stock piling of materials that dry out and

once disturbed fine dust particles are created. It was agreed that the stock piling of

materials would be damped down throughout the demolition operation also that they are

damped down before demolition works starts and also once the demolition works have

been completed for a period. Were possible all demolition materials to be loaded and

taken to the reprocessing area away from the demolition site. Clifford Devlin Ltd agreed

with this and would ensure that further demolition work would only continue with any

stockpile areas being fully wetted and damped.

3- I suggested that a further moto fog be directed at the base of the demolition area to

further prevent any dust vortex and suppress dust at source. The joint venture and Clifford


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Devlin agreed with this and indicated that they were bringing to site an additional moto fog

to keep this area of demolition fully suppressed.

4- As an independent demolition consultancy we are often involved in research and

development for demolition and have suggested one other demolition technique for

suppressing dust which has been designed by AR Demolition in the UK. It is a dust boss

which has been fabricated to the end of a telescopic handler which can be raised directly

to the demolition interface and the dust jet sprayed directly onto the work area. We only

know of a couple of these in production in the UK and have indicated and given Clifford

Devlin Ltd the number for this machinery. We have used this type of equipment many

times on contracts throughout Europe with Despe Limited and can confirm that it is

extremely effective. Failing that we know no other dust suppression techniques which

would assist the high reach demolition any further than the ones indicated in the report.

Clifford Delvin indicated in the peer review that they had sourced additional moto fogs and

water suppression techniques and would also constantly soak the materials at ground

floor level. They have also confirmed that they would soak the materials that were being

loaded to be removed to the crushing area and would keep all roads and surfaces

damped down at all times.

Figure 12 -Example of AR Demolition telescopic dust boss unit

Methodology

The use of the high reach as a methodology was already pre agreed prior to C&D Demolition

Consultants Ltd being asked to produce a report on the dust limitation issues. Therefore we

are unable to comment on the reasoning or price implications that this method was being

used at the design stage. However, I can confirm during my two visits that the methodology

was compliant and also was having no impact on the residents or the local area from both my


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analysis of any visual dust migration or on reviewing the onsite six dust monitor stations. In

relation to health and safety it was clear that no operatives were working at height or was

there any danger to the site operatives or general public. With only the ability to judge the

methodology since our appointment it was clear that the methodology being adopted was

both best practice and compliant.

Conclusion

To be clear my brief was to ascertain that the high reach demolition methodology was

compliant with current regulations. Further to this I was also tasked to see if the joint venture

dust strategy was compliant. In relation to the high reach demolition it is compliant with

BS:6187-2011 and it is also compliant with NFDC high reach rig guidance notes. The driver is

trained above 30m to operate the excavator. The curtain to prevent debris spill has been

assessed and is compliant. It also follows the guidance of the EDA and the methodologies

have been written and approved by a NFDC demolition company. Also, the Director of

Clifford Devlin is a full member of the Institute of Demolition Engineers.

On the evidence I have reviewed and the site visit and the knowledge of current demolition

legislation I am happy to confirm that the demolition methodologies being undertaken are not

only compliant but can be deemed as best practice.

Specifically, in relation to the dust the joint venture and Clifford Devlin Ltd have not only

complied with BS:6187-2011, NFDC guidance notes in relation to high reach and exclusion

zones. They have also been mindful of the Institute of Air Quality Management’s guidance

from dust and demolition 2014. On reviewing the evidence, I can confirm that not only are

they compliant and have carried out beyond reasonably practicable dust suppression that

they are leading by example and are producing best practice suppression techniques. Clifford

Devlin Ltd are employing six of the seven dust techniques available within the UK and are not

employing the seventh as it is not commercially available currently.

Based on my peer review I am happy as a full member of the Institute of Demolition

Engineers that the demolition techniques and dust suppression are not only compliant but

industry best practice.

MIDE AssocRICS MIIRSM GradIOSH AIExpE


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FIDE RMaPS FIConstM FICC AIIRSM FILM


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Table of Figures Figure 1- BS:6187-2011 - Code of Practice for full and partial demolition .......... 4

Figure 2- European Demolition Association high reach demolition notes ........... 5

Figure 3- NFDC Demolition Exclusion zone guidance notes .............................. 5

Figure 4 - NFDC Demolition high reach guidance notes .................................... 5

Figure 5- institute of Air quality management assessment of dust from

demolition and construction ............................................................................... 6

Figure 6 - Example of a dust curtain being used on a high reach demolition

contract ............................................................................................................. 7

Figure 7- Example of a waterjet direct feed to high reach's attachment ............. 8

Figure 8- Example of a dust boss ...................................................................... 8

Figure 9- Example of a moto fog working .......................................................... 9

Figure 10- Handheld demolition at ground level .............................................. 10

Figure 11- Operative working from a cherry picker with a handheld suppression

unit .................................................................................................................. 11

Figure 12 -Example of AR Demolition telescopic dust boss unit ...................... 12


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Appendix 1 – Table of material reviewed

1- Silverdale Structural Demolition report – 1EW02-CSJ-DS-REP-

SSO1_SL03-000005

2- Demolition of Silverdale – Risk Assessment & Method Statement –

1EW02-SCJ-HS-MST-SS01_SL03-000073

3- Regents Park Estate Demolitions- Dust management Action Plan

4- Euston Approaches Environmental Management Plan – 1EW02-CSJ-EV-

PLN-SS01-000004

5- Air Quality Management Plan – 1EW02-CSJ-EV-PLN-Sooo-000005

6- RPE Long Reach Presentation

Documents

HS2 CAMDEN DEMOLITION AND DUST PROCESS REVIEW...Peer Review C&D Demolition Consultants Ltd were invited to attend a peer review at the Regents Park Estate on Thursday the 16th of January