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Project Management Challenges during the Construction of an Effluent Treatment Plant at Sukinda
Page 1 of 25
ABSTRACT
Tata Steel operates one of the largest chromite mines in India at the Sukinda Valley in Odisha. The
chrome ore produced is subsequently converted it to Ferro Chrome and sold to customers across the
world, making Tata Steel one of the top ten Chrome players in the world. A large quantity of water,
generated during mining and due to rainfall, needs to be handled during the mining operations.
Chrome Ore mainly contains tri-valent chromium oxide and a very small fraction of hexavalent di-
chromate. Water coming in contact with chromium ore preferentially leaches out soluble hexavalent
chromium from the ore body, as a result, water from the mine contains 0.2 – 4 mg/l of hexavalent
chromium against a safe limit of 0.05 mg/l for human consumption; requiring all water to be treated
before its release from the mines. Thus, Tata Steel has set up an Effluent Treatment Plant at Sukinda
with a capacity of ~108 million litres/day, the largest in the region, and possibly one of the largest
single location ETPs in India. This paper discusses how the challenges faced during construction of
this Effluent Treatment Plant were successfully tackled.
KEY WORDS
Chromite or Chromium Ore
Hexavalent Chromium
Effluent Treatment
Project Management
Construction
Optimization
Safety Management
Real Time Monitoring
Project Management Challenges during the Construction of an Effluent Treatment Plant at Sukinda
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INTRODUCTION
Describing Sukinda and its importance to India
Sukinda Valley, known for its high grade chromite deposits, is located in eastern state of Odisha,
India. This valley contains 99% of India’s chromite deposit. The ultramafic mass occurs sporadically
over an area of 420 sq. km around Sukinda(Fig-1). The deposit was first proved by geologists of Tata
Steel in 1949, followed by intensive exploration. TSL’s Sukinda Chromite Mines, with a mine
extending over 406 Ha, is the one of the largest chrome mines in India. The Chrome ore mined at
Sukinda has enabled Tata Steel to be the largest chrome alloy players in India and among the top ten
globally.
Fig – 1 : Tata Steel’s Chromite Mine at Sukinda
Chrome Ore
Chrome ore occurs as Chromite, which is chromium oxide, and is essentially in the form of un-
weathered, hard, compact, fine grained dark grey lumpy ore or as a weathered, and loosely bonded,
brown-black, friable ore in ultra-basic host rock(Fig-2). Chromite contains mainly stable trivalent
oxide of Chromium with a small fraction in the unstable hexavalent state.
Project Management Challenges during the Construction of an Effluent Treatment Plant at Sukinda
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Fig - 2 : Weathered Friable Ore and Massive, Un-weathered Lumpy Ore
Hexavalent Chromium
While trivalent compounds of chromium are not soluble in water, hexavalent chromium compounds
are. Water coming in contact with chromium ore leaches out soluble hexavalent chromium from ore
body. Both mine water and surface runoff have 0.2-4 mg/l of hexavalent chromium against the safe
limit of 0.05 mg/l for human consumption.
Hexavalent chromium (Cr+6) is considered a human carcinogen with geno-toxic properties.
Hexavalent chromium can cause the following diseases:
Ingestion of hexavalent chromium contaminated water causes irritation and ulcers in the
stomach and the intestines
Contact with hexavalent chromium (in the form of dust or dissolved in water) with soft
mucous tissues of the eyes and the nose can lead to irritation and ulceration
Exposure to liquids/water contaminated with hexavalent chromium causes allergic skin
reactions
There is no evidence of elevated levels of these diseases (compared to the national and the state
average) in the valley. Another study, by Utkal Polyclinic, has also showed a lower incidence of skin
diseases in the Sukinda Valley, which, due to the allergic effects of Cr+6 on skin, is contrary to
expectations. This is probably due to the low levels of Cr+6 found naturally (and in Sukinda).
Project Management Challenges during the Construction of an Effluent Treatment Plant at Sukinda
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Water Management at Sukinda Mines
The Sukinda Valley experiences about 110 cm to 180 cm of rainfall annually, of which eighty per-cent
(80%) occurs during the monsoon season i.e. between June and September. Owing to this highly
uneven distribution of rain, the weather in the Sukinda Valley ranges from extremely dry to
extremely wet.
The major portion of the rain goes as surface runoff, and flows through the garland drains, that have
been made around the quarries and dumps. The flow carries silt and dry vegetation with it, apart
from picking up hexavalent chromium as it trickles down the chrome rich quarries and dumps. These
drains also channel the water pumped out during mining operations. (Fig-3)
Fig – 3 : Map showing water discharge circuit, garland drains and ETP Locations
History of Hexavalent Chromium Management at Sukinda Mines
Hexavalent Chromium in the Sukinda Valley water was first detected in the mid-1990s. Tata Steel
pioneered the efforts to mitigate the ill effects of hexavalent chromium by collaborating with India’s
premier environmental research institute, NEERI, Nagpur and set up three Effluent Treatment Plants
(ETPs) based on technology co-developed with NEERI. Initially, spent pickled liquor, from Tata Steel’s
old Sheet Mills was used to reduce hexavalent chromium; and later a process using FeSO4 was
established. (Table – 1)
Project Management Challenges during the Construction of an Effluent Treatment Plant at Sukinda
Page 5 of 25
Sl.
No.
Effluent
Treatment Plant
Year
Established
Capacity To Treat Process Used
1 Pilot ETP with
NEERI
1998 200 m3/hr Mine
Water
Reduction of Cr+6 using spent
pickle liquor.
2 Up-graded ETP-1 2002 715 m3/hr Mine
Water
FeSO4 based treatment with
gravity sand filters
3 ETP-2 and ETP-3 2003 3000
m3/hr
Surface
Run-off
FeSO4 based treatment with
baffles and roughing filters
Table – 1 : History of Effluent Treatment Plants at Sukinda Chromite Mines, Tata Steel
IMPETUS TO UPGRADE
While the pioneering efforts of Tata Steel in setting up Effluent Treatment Plants were well
acknowledged, there was a growing pressure to upgrade the (over ten year old) ETPs, both internally
and from the Government agencies, due to the following reasons :
1. Partly in order to mitigate environmental effects due to its mining operations and partly to
meet statutory obligations, Tata Steel has been conducting a very successful afforestation
program around the Sukinda and Kalarangiatta areas. Other miners at Sukinda too have
made some efforts in afforestation which has resulted in good rainfall.
2. Tata Steel’s Sukinda Chromite Mine is already one of the deepest Open Cast Chromite Mines
in India. As open cast mining is reaching the ultimate pit bottom, Tata Steel has long been
contemplating starting Underground Mining at Sukinda. This will further increase the
quantity of water that needs to be handled.
3. The ETPs set up in early 2000’s were possibly state of art at that time. However, with
facilities available for automation, online monitoring etc., and an increased understanding of
water treatment methods, the ETPs seem to be extremely maintenance and manpower
intensive today, and technologically obsolete.
4. The State Pollution Control Board, Odisha (OSPCB), hired IIT Kharagpur to conduct a study
on possible solutions to the issue of water pollution. The study recommended that a
common Effluent Treatment Plant be set up by OSPCB treating all water before reaching the
Damsala River.
However, the common ETP proposal was a non-starter because :
a. It was complicated, and not easy to execute on the ground; primarily due to requirement
of channelling all the water from the valley to one location, which would be challenging
due to (i) the large undulating contour of the Sukinda Valley and (ii) the vast area to be
covered.
b. The common ETP would require a large amount of capital expenditure. Sharing of the
capital expenditure between different mine owners was an extremely contentious issue.
Also, land for the ETP and right of way for the drainage would have been bottlenecks.
c. Operations of the Common ETP would be challenging too, given the different operating
philosophies, that different mine owners have.
Project Management Challenges during the Construction of an Effluent Treatment Plant at Sukinda
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Due to the above issues, it was decided that all the mines would set up their own ETPs individually
based on the conceptual design provided by IIT, Kharagpur to treat water generated from their
mines (including surface runoff) inside their leases.
Project Management Challenges during the Construction of an Effluent Treatment Plant at Sukinda
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CHOOSING THE RIGHT TECHNOLOGY AND EXECUTION STRATEGY
1. Evaluation of various techniques to treat Cr+6 and why we chose FeSO4 technology
There are many solutions to eliminate hexavalent chromium from water. Some technologies are well
established and in use commercially for specific situations. There are also some innovative solutions
that have been proven experimentally. A summary of the available technologies, and the reasons for
the selection of the FeSO4 technology is summarized in the table below (Table 2) :
Sl
No Technology Process Details Advantages Disadvantages
Suitability to treatment of
mine water
1
Physical
Adsorption of
soluble
chromium
ions(Cr+6)
Use of active
absorbents like
activated charcoal,
zeolites etc.
Fast Kinetics – able to
deal with large volume
of water
Low Cost
Narrow pH range,
Fouled by suspended
solids,
tolerance
Unsuitable due to TSS &
pH
2
Electro
chemical
treatment
Electro-coagulation by
electrolytic oxidation
of the ‘sacrificial
electrode’.
Wide pH range
Tolerant to suspended
solids
Cost (sacrificial
electrode & electricity)
High sludge
Moderate kinetics in low
concentration
Unsuitable due to cost,
moderate speed of
treatment in low
concentration
3
Osmosis/Mem
brane
separation
Using ultra-filtration
membrane to remove
Cr+6 ions based on
size exclusion
High removal efficiency
(>85%)
Low solid generation,
Low chemical
consumption
Narrow pH range,
Fouled by suspended
solids,
High Cost of membrane
Unsuitable due to high cost,
Low speed of treatment
4
Bio-
remediation
Using Microbes,
especially bacteria
capable of Chromium
(VI) reduction
Eco-friendly
Highly selective
Operational
flexibility(can be grown
in existing drains)
Low operational cost
Narrow pH &
temperature range,
Fouled by suspended
solids, oil & other
contaminants,
Effect of bacteria on
animals & humans not
known fully.
Unsuitable due to
intolerance to variations in
pH, temperature,
contaminants
& possible ill effects of
bacteria
5 Phyto-
remediation
Using plants which
accumulate toxic
compounds i.e.
Chromium (VI)
Very cost effective Has
aesthetic advantages&
long term applicability
Eco-friendly
Tolerant to pH &
suspended solids
Very slow process,
Phytotoxic at high
concentration
High space requirement
Plant waste needs to be
buried
Unsuitable due to the very
low process kinetics
Large space requirements
& possible ill effects of plant
bio-mass
6 Chemical
Precipitation
Chemical Reduction of
soluble Cr+6 to
insoluble Cr+3
Fast reaction
Time tested
Tolerant to variations in
pH and to high TSS
Medium Capex
Simple well understood
operation
High Sludge generation,
Extra operational cost
for sludge disposal
Method chosen due to prior
experience, fast reaction
time, low space
requirement. Tolerance to
TSS, pH, temperature
variations, very well
understood process
* Ref : IFA/ABP/389/2013 – Dr Y Rama Murthy et al, Jun-14(ref. 1)
Table – 2 : Selection of Right Technology from the Available Options for Remediation of
Hexavalent Chromium Effluent.
Tata Steel, along with CLRI, has also developed a Herbal Treatment process using Terminalia
Chebula, an organic product, for Cr(VI) removal in chromite concentrates; but the process is not
suitable for treatment of Cr+6 in mine effluent, given the volume of water to be treated, the slow
reaction rate & the cost of Terminalia Chebula(ref. 2)
Project Management Challenges during the Construction of an Effluent Treatment Plant at Sukinda
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2. ETP Process Design : Optimization of the treatment
Before designing the process, extensive jar tests were carried out on the effluent water to allow for :
a) Highly efficient and fast reaction for the reduction of hexavalent chromium Cr+6 to Cr+3 .
b) Rapid flocculation of precipitated Cr+3 compounds to reduce residence time in the Clariflocculator,
while enabling control of TSS within statutory limits.
Both the above are necessary to increase the throughput of the ETP and enable treatment of a large
volume of water in a short time. As a result of the jar tests, we have included three more facilities in
the ETP, which were not in the original design, namely :
i. Acid Dozing of the raw effluent in a flash mixer to bring down the pH before reaction with FeSO4
since the FeSO4 reaction is most efficient at a low pH. Also, because of the efficient reaction at
low pH, the consumption of FeSO4 and the amount of sludge generated can be substantially
reduced.
ii. Stirring arrangement in the flash mixer and a reaction channel to allow for complete reduction of
hexavalent chromium.
iii. pH correction using an alkali before dozing with a polyelectrolyte, to ensure complete reaction, as
polyelectrolyte reaction needs a neutral pH, along with a stirring arrangement. The alkali
recommended for pH reduction is NaOH but for various reasons we are using Ca(OH)2.
3. Sizing of the Effluent Treatment Plant
To determine the most suitable size for the effluent treatment plant, we needed to determine
the volume of both mine water (water pumped out from the mines during operation) and the
surface run off. The determination of mine water volume was simpler, due to ready data
available from which a correlation between mine production and water volume could be
obtained(ref. 3). The volume of mine water then was approximated from the long term plan for
mining, inclusive of the planned shift to Underground Mining. Determining the surface run-off
was more difficult. For this, we studied the water flow pattern and the meteorological data over
the last seven years for the region. The maximum rainfall over 24 hours in the last ten years
formed the basis for the calculation of surface run-off volume. The most likely maximum volume
of water that would need to be treated, thus determined, became the basis of determining the
size of the Effluent Treatment Plant. This resulted in us recommending the setting up of an ETP
capable of treating 4500 m3/hr; by far the largest ETP in the region. Other miner owners arrived
at far smaller ETPs, but subsequent events proved that we were correct. A year(and a rainy
season) later, many of the neighbouring mines are already expanding the capacities of their much
smaller ETPs.
4. Specifications for the Effluent Plant Output
We took a decision that the Effluent Treatment Plant output would not only meet the current
specifications for treated effluents in non-urbanized areas, but in order to be future ready, meet
Project Management Challenges during the Construction of an Effluent Treatment Plant at Sukinda
Page 9 of 25
the specifications for treated effluents in both urban areas and the likely stricter norms for
treated effluent that are likely to be imposed in the future. Thus the plant has been designed
such that the output has less than 0.01 mg/l of Cr+6 against a norm of 0.05 mg/l and meets the
stricter TSS standard of < 10mg/l (drinking water specifications) against a norm of < 100 mg/l
(norms for treated effluents in non-urbanized areas). We also took a decision to treat both
surface run off water and mine water in same way, which none of the other mines in Sukinda
planned to do. This decision proved to be fortuitous, as the Pollution Control Board has now
asked all mine owners to treat both surface run off and mine water and many mine owners have
had to look at augmenting the capacity of their ETPs.
Fig. 4 gives the capacity and guaranteed output water parameters of the Effluent Treatment Plant
at Sukinda (Fig 4)
Fig - 4 : Capacity and Guaranteed Output Water Parameters of the Effluent Treatment Plant at
Sukinda
5. Modular ETP
The wide variation in the quantity of surface water to be treated between the monsoon months
of June-Sept (where over eighty per-cent of the rainfall takes place) and the very dry months in
winter (Nov-Dec) and peak summer(Apr-May) posed its own challenges. Instead of making a
single large 4500m3/hr Effluent Treatment Plant, which would unnecessarily increase operations
cost in the dry period, we decided to make the ETP in three modules of 1500m3/hr capacity each
(Fig 5).
Project Management Challenges during the Construction of an Effluent Treatment Plant at Sukinda
Page 10 of 25
Fig - 5 : Block Diagram of the Modular Effluent Treatment Plant at Sukinda (1500 m3/hr X 3
modules)
6. Locating the ETP
Building an ETP of 108 million litres/day capacity is a huge challenge due to lack of sufficient
available space in Tata Steel’s Sukinda Chromite Mines leasehold area. The site for the ETP was
selected considering two main aspects, namely
a. The selected location would have to be at the lowest point of the mine so that all the water
(mine water and surface run-off) could be channelized at the minimum cost using gravity.
b. There would need to be adequate space at the site so that a 108 million litres / day ETP can
be constructed at the site.
The best candidate (though with many shortcomings) for location of the said ETP was at the south-
west boundary of the lease, the area used for despatches and truck parking. Also, the main despatch
road ran through almost the middle of the selected area. Thus we needed to first relocate the truck
parking yard and re-route the main despatch road, a big task by itself.
Due to the topography of the mine, some of the water would naturally flow to the north east
extremity of the mine, near the temple. Initially it was decided that we would need to construct one
of the ETP modules (1,500m3/hr) at the temple end and two ETP modules (2 x 1,500 m3/hr) at the
south west end(also known as the main site).
Project Management Challenges during the Construction of an Effluent Treatment Plant at Sukinda
Page 11 of 25
In a measure of further optimization, along with our Engineering Consultants, TCE, Jamshedpur and
execution partners, M/s EFFWA Infra and Research, Mumbai, the Engineering & Projects team at
Sukinda redesigned the layout of the modular ETPs such that all three clariflocculators could be
located next to each other at the main site with two collection tanks, one at the temple end and the
other at the main site; connected by a system of pumps and underground piping(Fig 6).
Fig - 6 : 3D View of the Modular Effluent Treatment Plant at Sukinda (1500 m3/hr X 3 modules)
7. Project Cost Optimization
In line with our tradition and philosophy of implementing the best environmental protection
measures and to remain a benchmark in the industry, we increased the capacity of the Effluent
Treatment Plant, with a concomitant increase in capital cost. We brainstormed to lower the cost
of the project, resulting in many innovative solutions, such as :
i. ETP at a Single Location : We had initially proposed construction of two separate ETPs at both
extremities of the mine. Every unit (pumps, motors, transformers, RCC tanks, clariflocculators
etc) would thus need to be constructed in both locations(albeit of a smaller capacity). Making
the ETP at one location, and the pumping of the effluent collected to the main ETP site; resulted
in substantial savings of about Rs XXX crores.
Project Management Challenges during the Construction of an Effluent Treatment Plant at Sukinda
Page 12 of 25
ii. Free supply of steel : We changed the terms of the contract to include free supply of re-bars,
which, being a product made by Tata Steel, was available to us at transfer prices (lower than
market prices due to lower taxes) and also gave us the advantage of assured quality, By this we
saved over Rs XXX crores in the project cost.
iii. Transmission of raw effluent partly through existing drains instead of through a underground
steel pipe : Initially we had planned to send the pumped raw effluent through a steel pipe.
However, on examination of the topography we found a natural slope from mid-way enabling
us to use the existing network of garland drains(after repairing them and increasing their
carrying capacity) to transmit the raw effluent. This resulted in a saving of Rs XX crores.
iv. Optimization of the steel structures, by evaluating the soil bearing capacity, for each location :
Initially we had taken a single measurement of the soil bearing capacity(SBC) at the centre of
the proposed ETP location. Because the SBC value was low, the structures were designed with
higher reinforcement. However, during excavation, it was found that the area, being partly
refilled, had widely varying SBCs. SBC values for each structure were measured and the
structures were re-designed, resulting in a substantial saving in construction cost, about Rs XX
crores.
v. Changing the sludge disposal method : Initially we had planned to handle dry sludge (less than
30% moisture) from the centrifuge using a conveyor to the sludge yard from where it would be
re-handled. However, the conveyor was taking up a large amount of space that we could be ill
afford. To optimize space and improve subsequent operations, we re-designed the sludge
handling system so that the dry sludge falls directly into buckets from which it will be lifted by
the Placer Dumper for disposal. This has led to a reduction in cost by Rs XX crores.
These cost reduction measures, taken up through a DMAIC project(ref. 5), resulted in lowering the cost
by Rs XXX crores.
CHALLENGES DURING THE EXECUTION
The State Pollution Control board had given us a deadline of 31-Dec-2014 for setting up facilities to
treat mine water and 30-Jun-2015 for setting up of the complete ETP. This was a seemingly
impossible deadline, considering that we had to start from scratch, from choosing the technology,
the execution partner, the engineering consultants, getting capex approvals and executing the
project within the stiff timeline of one and a half years.
Getting the capex approval and post techno-commercial negotiations to choose the execution
partner and engineering consultants, took close to six months. To meet the challenge of meeting the
almost impossible deadlines, we decided to :
a) Initially concentrate on meeting the target of treating mine water by completing one module
of the ETP by 31-Dec-2014.
b) Completion of the second module of the ETP by 30-Jun-2015 to treat the surface run off.
c) Completion of the third module (to treat water from underground mining/increased capacity in
open cast) and other finishing jobs post meeting the above deadlines.
Project Management Challenges during the Construction of an Effluent Treatment Plant at Sukinda
Page 13 of 25
1. Keeping the Project within timelines
To keep the progress on track, we used the CCPM method along with Weekly Review Meetings at
the local level, a weekly report which was circulated right up to the VP(Raw Materials), and a
detailed monthly review with the design team.
A major challenge has been working through two very heavy monsoon periods, one at the start of
the project, where a lot of excavation was involved, and one towards the end, where the heavy rains
have notched up the difficulty of safe and timely work by several degrees.
To address the issue of the almost impossible timelines, we also had to start civil construction before
completion of detailed design and engineering. To ensure that this did not affect the project,
sequencing of drawing approvals, accuracy in design and detailed engineering etc. were ensured by
close coordination between the Project Team, the Engineering Consultants and the Execution
Partners.
2. Quality Checks
A system of field quality audits during project execution was established, along with the help of the
engineering consultants, for various parameters, as shown in the table below (Table 4) :
Soil Tests Tests for Concrete Strength Tests for structural Integrity
Soil Bearing
Capacity – SBC
Sieve analysis for
coarse and fine
aggregate
Water absorption and
compressive strength
tests for fly ash brick
Water
tightness test
for RCC tanks
Holiday test for
wrapping and
coating of MS
pipe
Soil compaction
test for plinth
filling
Compressive
strength tests for
concrete (cube test)
Slump test for
concrete
Dye Penetrant
test for
welding joints
The tests were done at the laboratory established at the construction site or through a Government
Accredited laboratory at Bhubaneswar
Table – 4 : Summary of Quality Checks during the Construction of the ETP
Project Management Challenges during the Construction of an Effluent Treatment Plant at Sukinda
Page 14 of 25
Many facilities were set up to ease construction and improve construction quality as shown in table
below (Table 5) :
Sl No Detail of Facilities Set Up Description & Purpose of Facility
1 Batching Plant for concreting 6500 m3 of concreting jobs are to be done with desired quality of
M30 & M25 grade concrete.
2 Laboratory for site test Site laboratory set up for conducting Site tests as described in
Table 3.
3 Construction material storage
spaces
Space management was a challenge, in order to accommodate
1. Sand of Zone- III,
2. Aggregates of various sizes (10 mm -40 mm) in different
piles,
3. Covered cement storage area
4. 10,000m3 of excavated earth.
4 Equipment storage sheds Storage shed for equipment :
1. Electro-mechanical,
2. Cables (HT, LT, Control etc.),
3. Transformers, VCB, Panels etc,
4. Other equipment(pumps and Motors) etc.
5 Material fabrication & storage
yard
For various jobs like :-
1. Rod cutting, bending (640 tonnes of steel)
2. Scaffolding material storage yard
3. Scrap material yard etc.
6 Inside road for material handling For material handling we had to also provide a 4m wide road in
the constrained area.
Table – 5 : Various facilities set up during the construction of the ETP
3. Safety Challenges during Execution
a) Making the Site Safe from Normal Operations The best candidate (though with many short-
comings) for the location of the ETP was at the south-west boundary of the lease, the area used for
despatches and truck parking. However, the main despatch road ran almost through the middle of
the selected area. Thus we needed to first relocate the truck parking yard and re-route the main
despatch road, a big task in itself. This helped in ensuring that the construction site was kept
separate from normal operations and greatly increased safety during construction.
b) Weather Proofing : A major challenge has been working through two very heavy monsoon
periods, where the heavy rains notched up the difficulty of safe and timely working by several
degrees. To ensure safe working we ensured that no foundation work (excavation, making of
columns etc), electrical work (HT cabling etc.) or erection work was scheduled during the monsoon
period.
Safety is not a bolt-on program that can be managed after the project begins; safety should
be integrated into how work is performed, as are cost, schedule and quality
Project Management Challenges during the Construction of an Effluent Treatment Plant at Sukinda
Page 15 of 25
Similarly, we ensured that during the very hot period from mid-March to mid-June, when heat
induced incidents are common, we scheduled all heavy work for the early mornings and late
evenings, and by taking precautions of ensuring adequate lighting and separate gangs of workmen
and supervisors, sometimes, working through the night, instead of during the day.
c) Lack of space, mentioned earlier, has also meant that the work that could have been carried out
in parallel at any other site, per-force has had to be sequenced because of safety and other
execution concerns.
4. Site Safety
Safety is not negotiable, and we at Tata Steel, through years of training, efforts and learning from
incidents have made safe working almost second nature. This is also true for most of our contractors
and partners. However, our execution partner M/s Effwa Infra & Research and their sub-contractors
were working with Tata Steel for the very first time. We were also unable to ensure adequate
training on construction activities, since the training program at Sukinda is tuned more to sae
working in mines. Hence, we had to jointly develop safe working SOPs, HIRA and training of
workmen during the execution of the job. Inadequate planning and sequencing of jobs is a major
cause for onsite incidents. Timely and regular safety audit in the initial stages by external teams,
helped us greatly in identifying hazards(ref 4) Post the audits, we developed many safety protocols
which were implemented in letter & spirit.
Adopting Safe Construction Practices : The severe restriction in space and other difficulties led us to
adopt safe and at times unique construction practices, a few examples being highlighted below :
a) Pump House area– This area is highly space constrained. Drawings for pump house were
approved after the completion of construction of the Clariflocculator-1. Due to the pump
house being almost 3 meters lower than the Clariflocculator, an almost vertical cut needed
to be made for the raft of the pump house, where the shear resistance angle of the soil was
~ 10o < Φ ≤ 35o . Hence, we made sheet piles to stabilize the slope before excavation of the
pump house structure.
b) Deep Excavation– The tank structures involved very deep excavation, of over 4 meters
below the ground. Due to constraints of space the slope angle was greater than the angle of
shear of the soil. We used slope stabilizing nets and shoring to stabilize the slopes.
c) Ground Water Seepage– The deep excavation resulted in constant ingress of ground water
in the excavated pits. Thus constant pumping of the water while casting needed to be done,
which was risky as well as complex. Protocols developed especially for such situations
ensured close coordination between the pumping and casting gangs and safe working in
these risky situations.
d) As there was a High Tension Line running close to the project site, we shifted the 11kV line
with proper shutdown planning with the help of CESU to ensure that we could work safely.
The safety performance achieved during the period of construction is shown in the following table.
Project Management Challenges during the Construction of an Effluent Treatment Plant at Sukinda
Page 16 of 25
Project Management Challenges during the Construction of an Effluent Treatment Plant at Sukinda
Page 17 of 25
UNIQUE FEATURES OF THE EFFLUENT TREATMENT PLANT
The Effluent Treatment Plant under construction at Sukinda has many unique features(Table-6) :
a. 24/7 real-time monitoring of the input raw effluent and output treated water for Cr+6, pH and
TSS through online monitors installed at both input (raw effluent) and output (treated water).
This will prevent any inadequately treated effluent from leaving the mine and give warning
signals if the treated output water quality is not up to the mark.
b. The ETP is highly automated, with a feedback mechanism. Thus the dozing of chemicals (acid,
FeSO4, alkali, and flocculants) is automated through a system of PLC based controllers, based on
the input raw effluent and the output water quality.
c. Automated backwash arrangements for the pressure sand filters to ensure that the filters do
not choke.
Project Management Challenges during the Construction of an Effluent Treatment Plant at Sukinda
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b) ETP Technology Additional Facilities
Technology chosen is
- Highly efficient & rapidly reduces hexavalent chromium to trivalent chromium
- Causes rapid flocculation of precipitated Cr+3
compounds - Reduces residence time in the
Clariflocculator, while enabling control of TSS within statutory limits
This has increased the throughput of the ETP and enables treatment of a large volume of water in a short time
i. Acid Dozing of the raw effluent in a flash mixer to bring down the pH before reaction with FeSO4 since the FeSO4 reaction is most efficient at a low pH. Also, because of the efficient reaction at low pH, the consumption of FeSO4 and the amount of sludge generated is substantially reduced.
ii. Stirring arrangement in the flash mixer and a reaction channel to allow for complete reduction of hexavalent chromium.
iii. pH correction using an alkali before dozing with a polyelectrolyte, to ensure complete reaction, as polyelectrolyte reaction needs a neutral pH, along with a stirring arrangement.
These facilities have not been installed by other players
Design Elements Online Monitoring & Automation
The Effluent Treatment Plant is so designed that:
- the output not only meets current specifications for treated effluents in non-urbanized areas, but in order to be future ready, meet the specifications for treated effluents in both urban areas and the likely stricter norms for treated effluent that are likely to be imposed in the future.
- the plant has been designed such that the output has less than 0.01 mg/l of Cr+6 against a norm of 0.05 mg/l and meets the stricter TSS standard of < 10mg/l (drinking water specifications) against a norm of < 100 mg/l (norms for treated effluents in non-urbanized areas)
- treat both surface run off water and mine water in same way, which none of the other mines in Sukinda planned to do
The ETP has state of art online monitoring & automation systems :
a. 24/7 real-time monitoring of the input raw effluent and output treated water for Cr+6, pH and TSS through online monitors installed at both input (raw effluent) and output (treated water) to prevent any inadequately treated effluent from leaving the mine and give warning signals if the treated output water quality is not up to the mark.
b. The ETP is highly automated, with a feedback mechanism. Thus the dozing of chemicals (acid, FeSO4, alkali, and flocculants) is automated through a system of PLC based controllers, based on the input raw effluent and the output water quality.
c. Automated backwash arrangements for the pressure sand filters to ensure that the filters do not choke.
Table – 6 : Unique Features of the Effluent Treatment Plant at Tata Steel Sukinda Chromite Mines
Real Time Monitoring of Data
For real-time monitoring of data, we have set up a data communication system that captures real-
time information from the analysers for Cr+6, TSS and pH installed at the outlet in a server and
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transmit the data thus captured automatically to OPCB/ CPCB server on real time basis. The
schematic of data transmission is shown in Fig-7 and the output screen in Fig-8.
Fig - 7 : Schematic Diagram of Capturing & Transmitting Data for Real Time Monitoring
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Fig - 8 : Result of Online Monitoring of Treated Effluent - the effluent is well within the specified limits
Thus the output water quality data are available both internally through a dedicated web page and
can be transmitted to the Pollution Control Board on a real time basis.
Photographs of the Effluent Treatment Plant are shown at the end of the article.
CONCLUSIONS
The success of the ETP Project can be summarized to be as a result of the following :
i. Vendor selection only after an intense technical evaluation of the capability of the vendor
and not on commercial considerations alone.
ii. A strict focus on time lines and cost at all levels with frequent high level reviews and support
to the project team
iii. Over-riding concerns of safety and quality with mechanisms for frequent checks (preferably
external to project team)
iv. Deep understanding and cooperation between all agencies working on the project, which
developed during the course of the execution and was necessary to cope up with
unforeseen challenges that can crop up at any time : and need to be resolved
collaboratively.
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WAY FORWARD
The output water quality post treatment at the Effluent Treatment Plant is better than the water
available in the local Nullah, giving us the opportunity to use it as an input for our Water Treatment
Plant(WTP) and in various other places, like dust suppression, gardening etc.(Fig-10). The benefits of
this are:
a. Good Quality Water: During the monsoon season water flowing through Domsala river has very
high TSS. The output water from the ETP is already treated and thus a better input to the WTP
than the water from the Nallah.
b. Cost Saving : Apart from substantial cost saving in pumping from the Nallah which is over 3 km
away, the chemical consumption at the WTP will substantially reduce, due to the consistent and
better input water quality, reducing the cost of treatment as well.
c. Towards Zero Discharge : As per the Pollution Control Act, an industry should ideally have ZERO
discharge. Thus reusing the water from the ETP is one step towards achieving zero discharge.
Fig - 10 : Schematic Diagram of our plan to use the ETP discharge as an input to our WTP
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PHOTOGRAPHS
The Effluent Treatment Plant (View of Clariflocculator #1)
Panaromic View of the ETP showing the centrifuge building,
the chemical building and the power sub station
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Filter Beds and Raw Water Tank
Three Clariflocculators of 38m diameter
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Filter Gallery and Treated Water Tank
Inauguration by MD, Tata Steel and other Senior Officials
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References
1. Rama Murthy Y (Dr) et.al, IFA/ABP/389/2013, Development of Process for Water Treatment
at Chrome Ore Beneficiation Plant, Sukinda, Jun-14.
2. Kapure, Gajanan et.al., Application of Terminalia Chebula for Removal of Hexavalent. ISIJ
International, Vol. 48. 2008.
3. Internal Report on Water Quality & Runoff Management at Sukinda Chromite Mine, 2012.
4. Internal Safety Audit Report, Pravin Srivastava & Anirban Mukherjee, Sept-2014.
5. ASPIRE/DMAIC/2829 “Reducing Cost of Construction of Effluent Treatment Plant at Sukinda
Chromite Mines”, Apr-15.
ACKNOWLEDGEMENTS
Acknowledgements
The authors would like to place on record their gratitude to their colleagues at FA&MD – Sukinda
Chromite Mines – without whose help making the ETP would have been impossible; in particular, we
would like to thank the Mine Planning team for their help at all stages of the project. We would also
like to thank the Mining team, for the help during execution, and, RMPP, for the help in the initial
stages of the project.