pre – fabricated buildings in mining - an environment friendly alternative

MEMC WEEK 2016-17

Pre – Fabricated Buildings in Mining : An Environment Friendly Option Prabhash Gokarn

TATA STEEL, Ferro Alloys & Minerals Division

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This article has been submitted for publication in the Mines Safety Publication 2016 under Director General,

Mines Safety (DGMS), the Regulatory Agency under the Ministry of Labour and Employment, Government of

India.

DISCLAIMER

I would like to thank the management of Tata Steel for their kind permission for allowing us to publish this paper. The views expressed in this paper are my

own and should not be construed as the official opinion of Tata Steel or the views prevalent in the company.

ABSTRACT

Pre-fabricated buildings (or simply, pre-fabs), are buildings that are manufactured off-site in

advance, usually in standard sections that can be easily shipped, and assembled at site. There are

many advantages of Pre-Fabricated buildings which make it especially suited to Mining Locations.

With the improvement in the materials used in making pre-fab buildings, the rising cost of labour,

safety & quality concerns, and environmental concerns of construction waste disposal; pre-fab

buildings are poised to increase in popularity. This article discusses our experience in making a pre-

fabricated office building at one of our mining locations.

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KEY WORDS

Pre Fab or Pre – Fabricated

Mining / Mining Site

Blasting (effects of)

Construction Safety

Construction Waste Management

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Introduction

A pre-fabricated building, informally a pre-fab, is a building that is manufactured and constructed

using prefabrication. It consists of factory-made components or units that are transported and

assembled on-site to form the complete building.

The first pre-fabricated and movable structures were invented in 16th century in India during the

reign of Akbar. These structures were reported by Arif Qandahari in 1579[Ref-1], used by the Mughal

Army for building semi-permanent castles as they moved across Central India to consolidate the

Mughal Kingdom.

In 1855, during the Crimean War, architect Isambard Brunel designed a prefabricated modular

hospital for Florence Nightingale. In five months he designed a 1,000 patient hospital, with

innovations in sanitation, ventilation and a flushing toilet. Similarly, after World War 2, much of the

reconstruction in war torn Poland, was initially through pre-fabricated structures. [Ref-2]

Pre-fabricated homes were produced during the Gold Rush in the United States, when kits were

produced to enable Californian prospectors to quickly construct accommodation. Homes were

available in kit form by mail order in the United States in 1908. Similarly, pre-fabricated buildings are

a feature of many mining sites in Australia. What is it about pre-fab buildings that make it attractive

to mining sites?

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Mining Sites - features

In general, mining sites have the following features :

1. They are located in remote areas, usually far away from industrialized areas; though the mining

activity itself brings some development to the region.

2. Availability of technical personnel especially for non-core activities is low. I.e. while mining

engineers, mining machinery mechanical engineers, mineral technologists etc. are attracted to

such sites due to long term employment prospects; getting experienced civil and structural

engineers is extremely difficult, since only a very few building/structures need to be built over

long time periods.

3. For reasons similar to the one above, the availability of skilled manpower locally is low, and

needs to be brought from outside. This entails higher cost of labour, and expenses relating to

providing them accommodation and more leave. Also, at times, problems with the local labour

crop up, which need to be dealt with.

4. Mining areas are very often characterized by extreme weather conditions – some of it due to

the location, and some of it brought about, unfortunately, due to deforestation and other

interferences with the natural conditions, that the mining activity bring with it.

5. Open Cast Mining often entails blasting. These blasts occur often, usually daily, giving regular

low/mild intensity shocks to civil structures based upon distance from the blasting zone. Over

time these shocks cause structural damage, which lower the life of the structures drastically

over the years.

6. Mining environments can be very corrosive to civil structures, because of the dusty

environment, coupled with extreme weather conditions, long rainy periods and excessive

vegetation. Sometimes, rules prevent the vegetation to be cleared (as in Sukinda Chromite

Mines) further reducing the life.

7. The mining area is constantly evolving and shifting. Hence at times, the areas where offices &

residences have been built, needs to be sacrificed for mining; and these buildings and structures

shifted to other locations.

8. Most mining sites are already grappling with issues of dust control, waste and dump

management, and pollution of surrounding areas, including local water bodies and underground

water. Since most buildings are constructed at the edges of the leases, with heightened

awareness and increased environmental activism, management of construction waste is a

growing problem in mining sites.

Pre-fabricated Buildings

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In most modern industries automation has played a big part in reducing the total number of working

hours with the intent of keeping a lid on prices, but the construction industry is intrinsically labour-

intensive, and on a building site the usefulness of automation is limited. Pre-fabricating buildings in a

factory-type environment has the potential to improve construction time and quality control, reduce

the impact of environmental factors and control costs.

Pre-fabricated housing was popular during World War II due to the need for mass accommodation of

military personnel. They were built as a quick & economic replacement for the housing destroyed

during the war. However the quality was low, and when such pre-fabricated housing was left in use

for longer than its designed life, it acquired a certain stigma.

However, modern materials, improvement in design and building materials and the rising cost and

non-availability of construction labour has made pre-fabricated buildings viable again.

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Advantages & Dis-advantages of Pre-fab Buildings

PRO: Construction Time: Pre-fabrication offers a significant improvement in construction time.

Where a normal build time for a house may take more than a year, a pre-fabricated home can

be completed in just a few months. The time advantages come from many areas, but include

having much better equipment on hand and in close proximity to the building site, the ability

to build the house in a central industrial location where suppliers are in close proximity,

improved worksite lighting and, in the case of manufacturers who have internal workspaces,

there are no weather delays. Factory yards are also generally neater and have much better

amenities for staff which ultimately helps to improve productivity.

PRO: Increased Safety of Operations: Due to the above factors, leading work shifting from the site,

where control is lower, to a factory where working is easier, and more in control, there is a

drastic improvement in safety.

PRO: Parallel Work Further Reduces Construction Time: In covered factories the construction

sequence can be modified to improve efficiency. It will also not be important to close up the

building before any of the internal work can be completed. In many cases many trades can

work simultaneously which greatly improves efficiency.

PRO: Reduced labour cost: Fabricating most of the structural components at a central location can

take advantage of economies of scale and specialization. For example, rather than paying a

team of framers to travel to a job site, cut lumber, nail it into place and clean up, framing

panels can be produced at a factory by people who do one job and do it well, in a facility that

lets them work at maximum efficiency. Depending on the type of construction, a job that

normally takes months to complete on-site can be finished in days or even hours of on-site

work.

PRO: Quality control : Quality control is a huge advantage of prefabrication. A factory site can

provide high-quality tools that are far superior to those being carried onto a typical worksite.

Better tools ultimately result in much smaller tolerances and improved finishes. Improved

lighting and dry conditions also ensure that workers have complete control of their work.

PRO: Better Aesthetics & Improved Energy Efficiency : Improved tolerances in construction have

obvious aesthetic advantages, but also result in improvements in energy efficiency. By

eliminating gaps that allow air ingression, the internal spaces will require less heating and

cooling.

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PRO : Higher quality materials : Components produced off-site can often be manufactured to

tighter specifications and using better raw materials than the same components built on-site.

Also since off-site manufacturers can use specialized tools and control the conditions under

which the components are made, the resulting components can exceed the quality of

anything built on-site. (i.e. reduced tolerances, thinner sections, engineered solutions)

PRO: Less Cost Over Runs : Because pre-fabrication occurs in a controlled environment it is easier

to estimate the actual cost of construction. Typical builders will make allowances for things

that may be unforeseen or unknown. These allowances will be incorporated into their

contract price. In pre-fabrication those allowances may be reduced or eliminated.

PRO: More Predictable Timelines : The controlled environment makes the building process more

predictable which should limit the risks of variations. Most pre-fabrication builders will offer

fixed-price contracts.

PRO: Economies of Scale : If designs are repetitive, where multiple copies of the same basic

structure are followed; there is a large cost advantage due to economics of scale.

PRO : Environmental Friendliness : Off-site manufacturing processes can be optimized to reduce

the amount of waste generated during fabrication. Since on-site work is reduced to

assembling prefab components, much less waste is generated at the job site than is typical of

traditional construction methods. Some prefab components are also designed with energy

efficiency in mind.

CON: Not necessarily cheaper : Even though there are numerous improvements in efficiency and

cost control associated with pre-fabrication, the construction price of a pre-fabricated home

will not necessarily be cheaper than conventional construction. Transportation of large pre-

fab structures may further add to the cost.

CON: Possible Limitation in size : Pre-fabricated buildings are limited in size by requirements for

permissible road widths and heights. These limitations are usually managed by splitting the

building into manageable modules that are joined together on-site. Careful design will result

in a building that suits the needs and isn’t compromised by the restraints of road transport.

Hence design limitations are there in prefabricated structures.

Construction Advantages of Pre-Fabs

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There are significant construction advantages of making pre-fabricated buildings[Ref-3], [Ref-4] :

1. Self-supporting ready-made components are used, so the need for formwork, shuttering and

scaffolding is greatly reduced.

2. Construction time is reduced and buildings are completed sooner, allowing an earlier return of

the capital invested.

3. On-site construction and congestion is minimized. Quality control can be easier in a factory

assembly line setting than a construction site setting. Better Safety.

4. Pre-fabrication can be located where skilled labour is more readily available and costs of

labour, power, materials, space and overheads are lower.

5. Time spent in bad weather or hazardous environments at the construction site is minimized.

6. Less waste may occur, because things are more predictable. Also, since most of the

construction occurs off site, in a controlled environment, systems to handle waste – by recycling

or proper disposal – are usually in place.

7. Advanced materials such as sandwich-structured composite can be easily used, improving

thermal and sound insulation and air tightness.

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Advantages that make Pre-fabs ideal for Mining Sites

As can be seen from the above, the advantages that make pre-fabricated buildings & structures idea

for mining sites include :

a) Since much of the construction is pre-fabricated in urban areas and then transported to the

remote mining areas, the impact of the non-availability of adequate technical personnel and

skilled manpower reduces.

b) Impact of extreme weather – specifically, the heat in summer and heavy rains in the long

monsoons in mines in this region – reduces because the assembly time at site is much shorter.

c) Reduced labour work at the site and more skilled work in the controlled factory environment

reduce the risk of safety incidences. This is further enhanced by possible automation in the

factory.

d) Since the pre-fab building is usually made of strong structural steel blasting shocks have lower

impact on them than standard RCC structures. Also the external coated steel components (roof

and walls) are less prone to the corrosive effects of dust, water and vegetation.

e) Pre-fabricated buildings can be designed for re-location. It may be possible to recover 50% to

75% of the building cost if the areas where offices & residences have been built, needs to be

sacrificed for mining; and these buildings and structures shifted to other locations.

f) Economies of scale, if multiple buildings need to be built.

g) Lower Construction Waste – much more environmentally friendly.

Some of the structures in mines that are increasingly made from pre-fabricated structures include,

administrative buildings and local mining site offices; rest sheds for labour; site toilets & change

rooms; crèches; labour camps for contract workmen; stores and warehouses. Increasingly, even

residential buildings and guest houses are being made of pre-fabricated buildings.

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OUR EXPERIENCE

Need for Relocating the Manganese Mines Office

Tata Steel’s Joda West Mines produces around 40% of the total annual production of TSL’s

Manganese Group of Mines. Around 60% production of Joda West is done from D Quarry, most of it

of high grade, which amounts to around 33% of FAP, Joda requirement of High Grade Mn. Ore.

The ore body having potential high grade Manganese Ore is available in the western periphery of the

existing quarry; which was adjacent to the old Mines Office, a RCC building. For safety, the

excavation in office direction was restricted to 30 m distance from the old office building. Also, due

to the proximity of the office building, blasting within 30m was not done, forcing sub-optimal

blasting.

Factors Leading to Choosing of a Pre-Fab building for Mn Mines Office

Since the existing Office Building needed to be abandoned and the mine extended to the site of the

building, we proposed to make a pre-fabricated building away from the current mining area. The

factors that led to choosing a pre-fab building are :

Our Experience in Project Execution – Prefabricated Office Building at Joda West Mn Mines

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Our experience with the construction of office building at Joda West Manganese Mines proved many

of the stated advantages of pre-fabricated structures, namely :

1. Reduced time of construction compared to a RCC building : we saved 6 to 8 months by choosing

a pre-fabricated building, compared to the time we would have taken for a normal RCC building

(ref Table -1 and Table -2)

2. Parallel work allowed us to progress during the heavy monsoon period : despite a long monsoon

season with heavy rains, characteristic of the mining location, due to the ability to carry out jobs

in parallel we were able to reduce the effect the monsoons had on the construction timelines,

something not possible in a RCC Building construction.

3. No Cost Over–Run and Better Scheduling: despite a long monsoon season with heavy rains,

characteristic of the mining location, due to the ability to carry out jobs in parallel we were able

to reduce the effect the monsoons had on the construction timelines, something not possible in a

RCC Building construction. The project estimated budget was Rs 2.00 Crs. Total expenditure is Rs

1.97 Crs, within the estimated expense.

Other Advantages Derived from Making Pre – Fab Structures

Serial No. Description of ActivitiesM1-1st

half

M1-2nd

half

M2-1st

half

M2-2nd

half

M3-1st

half

M3-2nd

half

M4-1st

half

M4-2nd

half

M5-1st

half

M5-2nd

half

M6-1st

half

M6-2nd

half

M7-1st

half

M7-2nd

half

M8-1st

half

M8-2nd

half

M9-1st

half

M9-2nd

half

Activity-1Foundation work - construction and completion

with foundation bolting

Activity-2Steel Structural Material arrival at site- Super

structure

Activity-3Erection and Installation of Super Structure and

sheeting

Activity-4Fixing and Installation of Laminated board in

inner - outer walls, Fixing of Doors, windows

Activity-5Electrical and LAN Wire connection, DB

Installation, Server Installation

Activity-6Procurement of Supply items - Modular type

Tables, Chairs, ACs, Light Fittings etc

Activity-7Installation and Commissioning of Table, chair,

ACs, False ceiling etc. - Furnishing work

Activity-8LAN Connection - Video Conferencing set-up,

Projector set-up, LAN Connection

Activity-9Beautification of Office Area - Boundary Wall,

Area lighting, paver stone, Pathway etc.

TA

RG

ET

DA

TE

OF

CO

MP

LE

TIO

N

Table - 1 : Actual Timelines for Construction of Pre-Fabricated Office Building

Jan-16 Feb-16 Mar-16Jul-15 Aug-15 Sep-15 Oct-15 Nov-15 Dec-15

Serial No. Description of Activities

M1-

1st

half

M1-

2nd

half

M2-

1st

half

M2-

2nd

half

M3-

1st

half

M3-

2nd

half

M4-

1st

half

M4-

2nd

half

M5-

1st

half

M5-

2nd

half

M6-

1st

half

M6-

2nd

half

M7-

1st

half

M7-

2nd

half

M8-

1st

half

M8-

2nd

half

M9-

1st

half

M9-

2nd

half

M10-

1st

half

M10-

2nd

half

M11-

1st

half

M11-

2nd

half

M12-

1st

half

M12-

2nd

half

M13-

1st

half

M13-

2nd

half

M14-

1st

half

M14-

2nd

half

Activity-1Foundation work - completion with

foundation with curing & Backfilling

Activity-2Column Construction with Lintel beam

etc.- RCC curing etc.

Activity-3 Brick Work for the walls etc.

Activity-4Roof Beam Rod Binding, Shuttering,

Casting, Curing etc

Activity-5Electrical and LAN Wire connection, DB

Installation, Server Installation

Activity-6Plastering Work - Inside and Outside

workActivity-7 Painting Work and Furnishing work

Activity-8Flooring Work - Tiles Fixing, Plumbing

work, Sanitary Work

Activity-9Proc & Inst of Supply items - Modular

type Tables, Chairs, ACs, Light Fittings

Activity-11

LAN Connection - Video Conferencing

set-up, Projector set-up, LAN

Connection

Activity-12

Beautification of Office Area - Boundary

Wall, Area lighting, paver stone,

Pathway etc.

Table - 2 : Timelines for Construction of a Similar RCC Building

Pre

-fab

com

plet

ion

Jul-16 Aug-16Jan-16 Feb-16 Mar-16 Apr-16 May-16 Jun-16Dec-15Jul-15 Aug-15 Sep-15 Oct-15 Nov-15

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1. Increased Safety

Safety is an essential and integrated part in Project Management and execution at TATA STEEL,

who strive to be the benchmark for safety in all areas of operation. By going in for a pre-fab

building, ensuring safe working became easier and we achieved benchmark safety severity index

of 2.57, well within limit.

Table - 3 : Safety Performance during the Construction of the Pre-Fab Building

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2. A Modern Office, With World Class Facilities

As stated earlier, as much of the construction is done off-site, the pre-fabricated office building at

Manganese Mines, Bichakundi could be been designed, planned, erected and furnished to be at par

with the best modern engineering design and technologies available on date; despite the office

coming up in a remote mining area.

The following features have been incorporated :

a. Super Structural Members - High strength Galvanized steel complying with AISI 1989 has

been used. In some areas Colour coated sheet Zincalume alloy coating as per AS 1397 has

been used.

b. Laminated board for inner and outer partition wall with Insulator Fibre Glass has been used,

which would provide adequate insulation, keeping the office cool even in hot summer

months.

c. High quality insulation boards that use best in class acoustic mineral fibre boards has been

installed, for eliminating noise pollution.

d. Highly energy efficient Air Conditioners, and LED Lights have used for saving electricity.

These actions, which comply to the Paris Climate Summit COP-21, UNCCC guidelines, which

attempts to reverse the 20C rise in global temperature, will lead to a saving of about 30,000

kWH of electricity consumption annually.

e. Best in Class Drainage System has been provided so as to avoid any water accumulation. The

drainage system has been so engineered that all water is collected and directed to recharge

ground water. We have also planned to install a water harvesting system that would re-

circulate the collected water for re-use.

f. Furniture : A modern semi-open sitting arrangement, at par with modern offices, has been

provided, with LAN connections, appropriate lighting etc.

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g. Space optimisation : The office has been designed to accommodate over 35 officials and

provide adequate office facilities like multiple conference rooms, Video Conferencing

arrangement etc.

Diagram – 1 : Layout of the Office Building (Area: 7798 sq ft).

3. Lower Construction Waste : Due to reduced Civil Work at site and the use of pre-fabricated

panels and structural material, the construction was much more environmentally friendly than a

building made using traditional RCC construction would be. This is particularly important, at

Bichakundi, where we have already been taking many steps to avoid contamination of surrounding

areas, including the local Sona River.

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Pictures of the Modern Pre-fabricated Office during Construction

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Pictures of the Modern Pre-fabricated Office after completion

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Conclusion

Pre-fabricated buildings have not yet caught the imagination of civil engineers and users – the

association with poor quality, mass produced and low end accommodation is very high. In fact, there

were many Nay-Sayers when we had to choose a pre-fabricated building to replace our existing

Mining Office at Bichakundi for reducing construction time.

However, going in for a pre-fabricated building helped us, not only crash timelines, but also

construct a high quality, very modern office, incorporating technologies for energy saving and water

conservation.

Advantages of increased safety during construction and reduced possibility of cost over-runs were

also realized. While we hope that the constructed building will remain at its present site and serve us

for many decades; in case it is needed to shift the office to a new location, due to operational

exigencies; the high salvage value of prefabricated buildings gives it a definite advantage over RCC

buildings.

Way Forward

In today’s fast changing world, there is a push towards Structural Buildings which get executed

faster, using less labour intensive technologies, at possibly lower cost, and with the ability to

incorporate energy efficient technologies.

With technological development in materials used in construction of pre-fabricated buildings, quality

is comparable to, and usually better than RCC buildings. While it is possible to make unique

architectural masterpieces each time; similarly designed pre-fabricated buildings can be made,

exploiting economies of scale, as well as giving a similar look and feel across installations. This can be

advantageous in some situations, e.g. Sales Points looking similar across locations drive helping

branding efforts.

The advantages of pre-fabricated buildings for mining sites have been described in detail. At Tata

Steel’s Ferro Alloys and Mineral’s Division, we will be exploring using pre-fabricated structures to

meet needs for :

1. Site Office Building

2. Security Barracks

3. Crèche building

4. Bio-toilets,

5. Low cost housing for labour

and, even

6. Regular housing for officers and staff

We look forward to sharing our experience with pre-fabricated buildings with others and look

forward to learning about their experiences as well.

ACKNOWLEDGEMENTS

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The authors would like to place on record their gratitude to their colleagues at FA&MD, Tata Steel

without whose help the construction of the Pre-Fabricated Office Building would have been

impossible. We would also like to thank our colleagues at TS Kalinganagar who shared their learning

in making pre-fabricated buildings which we were able to put to good use at Joda.

REFERENCES

1. Irfan Habib (1992), "Akbar and Technology", Social Scientist 20 (p9-p10)

2. Washington Post, "The Whole Kit and Caboodle", 2002-02-07

3. Chris Joseph, “Budgeting The Nest”, Demand Media Publication

4. Amelia Josephson, “The Pros and Cons of Prefab Homes”, SmartAssets.Com, 28-Jan-2016

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LIST OF FIGURES, DIAGRAMS & TABLES

1. Fig 1 : The Old Mines Office Building was 30m from the Mine Face

2. Fig 2 : Decision Matrix : Why a Pre-fab Building Was Chosen

3. Fig 3 : Civil Foundation in Progress

4. Fig 4 : Structural Members Being Erected

5. Fig 5 : External Members – Roof, Walls Erected

6. Fig 6 : Internal Flooring & Steel Structural Installed

7. Fig 7 : Internal Panelling, Wiring, Lighting, & Furnishing

8. Fig 8 : Internal Furnishing In Progress

9. Fig 9 : Completed Office – Inauguration Day

10. Fig 10 : External View of the Office

11. Fig 11 : External View of the Office

12. Fig 12 : New Office Building Inaugurated at Manganese Mines, Joda

13. Fig 13 : New Office Building Internal View : Modern Open Cabins

14. Fig 14 : New Office Building : Conference Room

15. Fig 15 : New Office Building : Officer’s Room

16. Fig 16 : New Office Building : Head’s Room

17. Fig 17 : New Office Building : Accounts Office

18. Table - 1 : Actual Timelines for Construction of Pre-Fabricated Office Building

19. Table - 2 : Timelines for Construction of a Similar RCC Building

20. Table - 3 : Safety Performance during the Construction of the Pre-Fab Building

21. Diagram – 1 : Layout of the Office Building (Area: 7798 sq ft).

pre – fabricated buildings in mining - an environment friendly alternative

Engineering