polkemmet colliery case study

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LANDPAC Ground Engineering Ltd Intelligent Ground Improvement ® CASE STUDY High Energy Impact Compaction (HEIC) Application Continuous Impact Response (CIR) Monitoring Continuous Induced Settlement (CIS) Monitoring HEARTLANDS DEVELOPMENT C C O S ( ) Project Facts: Project Name: Heartlands Development Site is on the former Polkemmet Colliery , west of Whitburn, south of M8 between Edinburgh and Glasgow in Scotland Project Site Area: 600 Hectares 30 000 000m 3 Total Open Cast Dig for Coal 10,000,000m 3 HEI C THI C K LAYER W O RK S ( TLW ) 30,000,000m 3 Total Open Cast Dig for Coal 10,000,000m 3 HEIC Engineered Development Platform for 5,000 houses 1.2m Thick Layer Work Compaction Average dig depth 30m (deepest being 42m) Average Production 200,000m 3 per week The Specification for the works required an end product dry density of 95 % of standard proctor to be achieved Project Start Date June 2004 Project End Date June 2009 (+ 6 months) Project End Date June 2009 (+ 6 months) Client – Ecosse Regeneration Ltd Funded – RBS & sale of Coal Consultant – WA Fairhurst & Partners Mining Contractor – J Fenton & Sons and Minrec NHBC Approval – Pending June 09 first 5 Cells End Development includes: o 5,000 Houses o 2 x Championship Golf Courses o Business/Industrial Park CIR overlay on one of the many HEIC thick layer work (TLW) ground Improvement Cells LANDPAC introduced its own unique ground response monitoring o Business/Industrial Park o New Junction 4A on M8 (Edinburgh to Glasgow) LANDPAC was key on delivering this project due to the high productivity resulting from open cast mine operations with 20 x CAT777’s and 4 x RH120 excavators, the shear scale of the area and depth of the site and the very tight time constraints in which to accomplish the desired completion date for the client. This was no ordinary open cast mine operation, where over-burden materials that are cut are generally backfilled into excavated cells with no controlled LANDPAC introduced it s own unique ground response monitoring system to the project. The Continuous Impact Response (CIR) monitoring system is a recording application, which captures continuously, stiffness profile data of the improved materials during the HEIC procedure. As a result this GPS integrated live monitoring system dictated the testing program throughout the project. The stiffness profile data basically indentified the weaker areas of the compacted layer (being 1.2m thick), in return allowed pin-point testing to be implemented, rather than costly “blanket testingThis further fast-tracked the project as greater volumes of are cut are generally backfilled into excavated cells with no controlled compaction effort. The project required continuous ground improvement engineering, precise test monitoring and simultaneous all party approval on a scale never attempted before. This was one on the largest civil engineering projects within Europe and was largely un-known due to it being an open cast mine operation. Now that all the coal has finally been taken off-site and delivered to surrounding power stations, concentration is on final design levels, preparing surface infrastructure and gaining NHBC approval for all HEIC engineered development platforms to allow house construction to testing . This further fast-tracked the project as greater volumes of materials were tested comprehensively, but with less laboratory test frequencies. Thus allowing greater integrity of the improved materials as displayed by the stiffness profile data captured at a frequency of 4m 3 through CIR which minimised Laboratory testing by to one test per 2,500m 3 . Verification testing was carried out at the site under the supervision of WA Fairhurst & Partners. The testing included in-situ density testing using Nuclear Density tests and Sand Replacement testing engineered development platforms, to allow house construction to start. If, as was investigated in early 2004, conventional compaction plant was to be used on the project then the project would never have been given the green light. As quoted by Alex Muirhead – Project Manager for Ecosse Regeneration Ltd “A standard heavy roller would normally only compact up to 400mm, if we did that, we’d have to roll each layer three times to reach 1.2m depth (HEIC layer works capability) if that were the case wed still be doing it in 10 years testing using Nuclear Density tests and Sand Replacement testing, Plate Load Testing, Zone Load Testing and monitoring of settlement pins. The testing was carried out with the benefit of LANDPACs CIR monitoring system, which allowed the Engineer to target the testing at the most critical portions of the site, i.e. those areas which were indicated on the CIR maps as being weaker than the surrounding soils. This ability to target the testing resulted in the test program being cut by 50% over what was originally envisaged. TLW Thick Layer Works TWP Temporary Working Platforms IGI In-situ Ground Improvement capability), if that were the case, we d still be doing it in 10 years time” – refer Construction News, issue 7105, pages 20 & 21, dated Thursday 19 th Feb 2009. The results of the testing, to date, confirmed compliance with the Specification. VC Void Creation

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Page 1: Polkemmet Colliery Case Study

LANDPAC Ground Engineering LtdIntelligent Ground Improvement

®C A S E S T U D Y

High Energy Impact Compaction (HEIC) ApplicationContinuous Impact Response (CIR) MonitoringContinuous Induced Settlement (CIS) Monitoring

H E A R T L A N D S D E V E L O P M E N T3 C C O S ( )

Project Facts:

• Project Name: Heartlands Development• Site is on the former Polkemmet Colliery, west of Whitburn,

south of M8 between Edinburgh and Glasgow in Scotland• Project Site Area: 600 Hectares• 30 000 000m3 Total Open Cast Dig for Coal

1 0 , 0 0 0 , 0 0 0 m 3 H E I C T H I C K L A Y E R W O R K S ( T L W )

• 30,000,000m3 Total Open Cast Dig for Coal• 10,000,000m3 HEIC Engineered Development Platform for 5,000

houses• 1.2m Thick Layer Work Compaction• Average dig depth 30m (deepest being 42m)• Average Production 200,000m3 per week• The Specification for the works required an end product dry

density of 95 % of standard proctor to be achieved• Project Start Date June 2004• Project End Date June 2009 (+ 6 months)• Project End Date June 2009 (+ 6 months)• Client – Ecosse Regeneration Ltd• Funded – RBS & sale of Coal• Consultant – WA Fairhurst & Partners• Mining Contractor – J Fenton & Sons and Minrec• NHBC Approval – Pending June 09 first 5 Cells• End Development includes:

o 5,000 Houseso 2 x Championship Golf Courseso Business/Industrial Park

CIR overlay on one of the many HEIC thick layer work (TLW) ground Improvement Cells

LANDPAC introduced it’s own unique ground response monitoringo Business/Industrial Parko New Junction 4A on M8 (Edinburgh to Glasgow)

LANDPAC was key on delivering this project due to the highproductivity resulting from open cast mine operations with 20 xCAT777’s and 4 x RH120 excavators, the shear scale of the area anddepth of the site and the very tight time constraints in which toaccomplish the desired completion date for the client. This was noordinary open cast mine operation, where over-burden materials thatare cut are generally backfilled into excavated cells with no controlled

LANDPAC introduced it s own unique ground response monitoringsystem to the project. The Continuous Impact Response (CIR)monitoring system is a recording application, which capturescontinuously, stiffness profile data of the improved materials duringthe HEIC procedure. As a result this GPS integrated livemonitoring system dictated the testing program throughout theproject. The stiffness profile data basically indentified the weakerareas of the compacted layer (being 1.2m thick), in return allowedpin-point testing to be implemented, rather than costly “blankettesting” This further fast-tracked the project as greater volumes ofare cut are generally backfilled into excavated cells with no controlled

compaction effort. The project required continuous groundimprovement engineering, precise test monitoring and simultaneousall party approval on a scale never attempted before. This was oneon the largest civil engineering projects within Europe and was largelyun-known due to it being an open cast mine operation. Now that allthe coal has finally been taken off-site and delivered to surroundingpower stations, concentration is on final design levels, preparingsurface infrastructure and gaining NHBC approval for all HEICengineered development platforms to allow house construction to

testing . This further fast-tracked the project as greater volumes ofmaterials were tested comprehensively, but with less laboratorytest frequencies. Thus allowing greater integrity of the improvedmaterials as displayed by the stiffness profile data captured at afrequency of 4m3 through CIR which minimised Laboratory testingby to one test per 2,500m3.

Verification testing was carried out at the site under the supervisionof WA Fairhurst & Partners. The testing included in-situ densitytesting using Nuclear Density tests and Sand Replacement testingengineered development platforms, to allow house construction to

start.

If, as was investigated in early 2004, conventional compaction plantwas to be used on the project then the project would never have beengiven the green light. As quoted by Alex Muirhead – Project Managerfor Ecosse Regeneration Ltd “A standard heavy roller wouldnormally only compact up to 400mm, if we did that, we’d have toroll each layer three times to reach 1.2m depth (HEIC layer workscapability) if that were the case we’d still be doing it in 10 years

testing using Nuclear Density tests and Sand Replacement testing,Plate Load Testing, Zone Load Testing and monitoring ofsettlement pins. The testing was carried out with the benefit ofLANDPACs CIR monitoring system, which allowed the Engineer totarget the testing at the most critical portions of the site, i.e. thoseareas which were indicated on the CIR maps as being weaker thanthe surrounding soils. This ability to target the testing resultedin the test program being cut by 50% over what was originallyenvisaged.

TLW Thick Layer Works

TWP Temporary Working Platforms

IGI In-situ Ground Improvement

capability), if that were the case, we d still be doing it in 10 yearstime” – refer Construction News, issue 7105, pages 20 & 21, datedThursday 19th Feb 2009.

The results of the testing, to date, confirmed compliance with theSpecification.

VC Void Creation

Page 2: Polkemmet Colliery Case Study

DOING THE JOB

A former industrial site in central Scotland is proving to be one of the UK’s

t h ll i ti j t

Funding value: £500 millionDeveloper: Ecosse Regeneration

most challenging regeneration projects

PROJECT REPORT

MARK ALEXANDER

Coal production in the UK isn’twhat it used to be. It reached itspeak during the early 1900swhen over 250 million tonnes ofthe black stuff was producedannually. The industry wasenjoying its heyday, respondingto growing demand for energy

which reportedly produced4,000 tonnes a day in the1950s. By the time the gateswere closed in 1985, it waslosing more than £8 for everytonne of coal it extracted.

Turning the clock forward,the deep underground workings

of sandstone, shale, mud stoneand waste coal that was volatileand noxious.

Underground, numerous coalseams crisscrossed the site.The main ones – Armadale Ball,Armadale Main, Colinburn andthe Mill – ran virtually the length

and community centre.With merits aplenty, planning

approval was duly granted in2004 with 137 planningconditions. Work startedimmediately, although at thatstage the land still bore thescars of its industrial past whichRegeneration

Compaction subcontractor: LANDPACRemaining-coal extractor:J Fenton & Son (Contractors)Development: Business park,up to 5,000 houses, two golf courses, two hotels, a school and community centreFill material per week:200,000 cumSite area: 611 ha

to growing demand for energyand pushing the boundaries ofengineering by sinking shafts togreater depths and extendingunderground workings furtherinto the ground.

When the industry’s declinecame, it was swift and brutalwith few escaping the cull.Among the pits to beunceremoniously shut wasPolkemmet colliery, one ofcentral Scotland’s mostsuccessful mines

the deep underground workingsand smouldering heaps of spoilneeded serious measures toready Heartlands for a severalhundred million investment.Over 60 years of production hadleft Polkemmet blackened andscarred. Worse still, theremnants of the miningoperations had been leftsmouldering in large mountainsof spoil, otherwise known asbings. The largest was a 2million cu m pile

the Mill ran virtually the lengthof the plot at different depthsand overlapped each other.This was a site with a corrosivelegacy that had been disfiguredby decades of industry bothabove and below the ground. Itwas unloved and had been leftto rot, but it was ideal forredevelopment.

Plan of actionAbout 120 ha of dereliction,never mind 83 ha of blanket

scars of its industrial past whichAlex Muirhead, project managerfor Ecosse Regeneration, willnever forget.

“It was the mostcontaminated site in Scotland,”he says. “It was big, desolateand unfriendly. Everywhere youlooked you could see whiterunning water filled withaluminium, burntout cars andblack tips. It was completelydepressing.”

successful mines million cu m pile never mind 83 ha of blanketbog, 31 ha of conifer woodlandand 3.7 km of watercourses,was a formidable undertaking.Taking on Polkemmet would bea huge commitment, offset bythe substantial strategic valueoffered by the site and thesurrounding pockets of land.

Located between Edinburghand Glasgow and adjacent tothe M9 motorway, the site’sappeal attracted a string of

Foundation workThe challenge wasconsiderable. At 4.9 km,Polkemmet was the deepest pitin Scotland. It also had othermines entering it which hadbeen worked from outside thearea. One of the mainstays ofthe regeneration plan was tomitigate the mines and makethe ground safe to build on.

“The deepest part of the siteapplications to West LothianCouncil to resolve thecontamination issues. Each wasrejected by the authority,unconvinced the schemeswould benefit the localcommunity.

The planners remainedunmoved until they saw the bidpresented by EcosseRegeneration, a developmentvehicle specifically set up tomanage the rejuvenation of

we dug was 42 m, and wecompacted earth from that levelupwards,” says Mr. Muirhead.

“Anything within 16 m we hadto grout or remove, althoughwhere we had the opportunitywe’d take out all the oldworkings. We shifted 30 millioncu m of rock and spoil and thatstarted in 2004, with the lastpiece of coal being taken out inFebruary 2008.

“We’re still putting themanage the rejuvenation ofPolkemmet and Heartlands.

Funded by the Royal Bank ofScotland, the plan was totransform the entire 611 ha siteusing £500 million to create abusiness park, up to 5,000houses, two 18-holechampionship golf courses, twohotels, a school

We re still putting therestoration in so we havecompetent golf course contoursand build platforms.”

The engineered platforms atHeartlands were created onland devastated both above andbelow ground level. Theprocess of rectifying theseareas

Page 3: Polkemmet Colliery Case Study

involved excavating largeswathes of land and thenrefilling the holes withcompacted earth. Because200,000 cu m of material wasshifted every week and used forfill, conventional methods ofcompaction were unsuitable. Aquicker solution was needed.

“We imported a compactionit th t d iunit that gave us dynamic

compaction on the move,” saysMr. Muirhead. “It has rubbertrack tyres and it tows aconcentric wheel that putsenergy into the ground. Itcompacts thicker layers quickly.We set the limit at 1.2 m, butwe know it influences belowthat because we do split-layertests.”

The Landpac system relieson high energy impactcompaction (HEIC) whichcompresses in-situ materials,creating soil with increasedengineering properties.

The process appears simplewith a tractor unit pulling anormally pentagonal-shapedsteel drum weighing up to 14tonnes across the ground. Thedepth of influence, however,can reach 2 m to 4 m,depending on the drum weightand its rotational drop heightand its rotational drop height.

“A standard 72 tonne rollerwould normally only compact upto 400 mm,” says Mr. Muirhead.“If we did that, we’d have to rolleach layer three times to reachthe 1.2m depth. If that were thecase, we’d still be doing it in 10years’ time.”

BurnoutThe problems at Heartlandsweren’t confined to the mine

k E il f d b i

Bing was 2 million cu m ofmaterial, 30m high,” says Mr.Muirhead. “There was a fuelsource, which was the coal, andoxygen which had been trapped

ithi it S ll d d

covering the bing werestringent, so to find out what laybeneath, Mr. Muirhead ordereda survey.

“Before we started, we drilledth bi t fi d t h th

no flare-ups or nasty smells totrouble the local community.

Like the rest of the site, theland where Bing 3 once stoodbears little resemblance to thed li ti th t il d

opportunities in a lifetime It’s like“you get one

of these

works. Enormous piles of debrislittered the site, with one bingregarded by many as WestLothian’s worst eyesore.Unfortunately, a combustiblemix of oxygen, heat and fuel(coal) not only made Bing 3unsightly, it also made ithazardous. Previous attemptsto remove the mound hadmerely exacerbated thesituation resulting in violentexplosions.

within it. So all you needed wasa heat source, which could havecome from compression or anexternal source. As soon as youopened it up, it would explode.

“Previous attempts to movethe bing in the late 1980s hadpolluted the whole of Whitburnand down towards Edinburgh.The smell of rotten eggs waspronounced. Black plumscovered the town, kids went tohospital with asthma and cars

the bing to find out where thehotspots were,” he says. “Wedrilled down until we hit 50 degC then filled up the hole. At onepoint the driller reached 50 degC a metre below the surface.”

The next step was to cap theburning areas of the bing withboulder clay, which not onlykilled the smouldering, but alsorestricted the smell. Siteworkers then removed debrisand compacted it in a purposely

dereliction that once prevailed.The green fields and buildplatforms that currentlydominate Heartlands belie theremarkable remedial work thathas taken place here.

“I’ve never worked on such acomplex, constrained andmonitored site,” says Mr.Muirhead. “But you get one ofthese opportunities in a lifetime.It’s like being a painter with ablank canvas.”

lifetime. It s like being a painter with a blank canvas.”ALEX MUIRHEADECOSSE RGERERATION

It wasn’t something Ecosse wasabout to repeat. “The Burning

were pitted by acid rain.”The planning stipulations

built hole. The process wassurprisingly straightforward, with

With the canvas ready, it’ll beinteresting to see what Mr.Muirhead will produce.

Compacting Basics

Direction of Travel

Cam Drops by approx 230mmCam Drops by approx. 230mm