PT&D PROJECTS SCALE-UP DELIVERY ACROSS GEOGRAPHIES

Powering Mumbai Metro Line 7

The stakes are high for Project Manager, P L Jarotiya, at the Mumbai Metro Line 7 project to deliver a set of composite tasks comprising laying an EHV cable along the Western Express Highway between Borivali to Dahisar, constructing a 110/33-25 kV receiving substation, installing auxiliary substations across the 13 metro stations and laying 148 Km of external HT cable. While the city was locked down, the project team diligently made inroads with special permissions and closed in on some of the most challenging milestones such as laying the EHV cable. “We executed mostly  during the restricted hours as it was a high-density traffic corridor with many existing underground utilities,” remarks P L Jarotiya. “Thanks to the support of the traffic police and the local authorities, we safely completed the entire trenching activity.”

Another consideration was to create space for mobility to mitigate the challenge of working over a running storm water drain. The project team came up with a temporary bridge and erected a 20 m high tower crane with a 35 m boom reach which enabled faster completion of works with lesser manpower, ensuring safety and quality. It is commendable that the project completed the main structural and finishing works within a 3-month period thus saving close to 2.5 months from the original schedule. The substation was charged on 24^th May 2021 which facilitated the overhead electrification of the line and the trail run. “It is a special milestone for us as this is the first substation commissioned by L&T for the Mumbai Metro,” shares P L Jarotiya proudly.

“To synchronize the auxiliary substations across the 13 metro stations, the onus was on the team to ensure that overlapping deliverables were precisely handed over to other civil and electrical agencies,” says Planning Engineer, Somen Debnath. “The client was keen to complete the testing of four stations on the priority section as soon as possible, which was achieved by handing over the completed sections of work fronts to the other stake holders for integration for testing and commissioning.” Going further, the project team has completed the installation and testing works including laying the HT cable at the 7 auxiliary substations.

P L Jarotiya attributes their success to some smart applications and proven strategies. “We installed optic view cameras at strategic locations across the GIS building, transformer yard, foundation work areas and main stores for 24/7 monitoring and real-time sharing of progress with the client.”

Building intricate power stations

With close to 96.61% of works completed at the 220/132 kV Layyah Substation in Sharjah, V. Oscar, Project Manager, has a lot to share on how the team went about achieving their milestones while overcoming the challenges of working in a brownfield project. “Our scope involved constructing a 220/132 kV substation, including 3 auto transformers to connect and regulate power from the new power plant as per the demand and transmit it to the network.”

One of the first challenges for the team was to work out a secure routing channel for the GIB connection with the new GIS building that was aligned through the existing 40-year-old power plant. “There was no detailed mapping of the existing utilities network,” mentions Planning Manager, Mohd Momin. “Finalizing the alignment was a composite task as it involved laying around 3900 m of GIB length, working out secure channels for the gas & road crossings and constructing a 12 m high & 330 MT supporting structure for the new GIB.

For Oscar and his Planning Lead, the primary concern was to plug the gaps in the existing services before progressing. By coordinating closely with the plant authorities, they synchronized the tasks with the other activities undertaken by external contractors who were also working in the same area. The first milestone was to energize the 132 kV substation in 18 months, but they faced an immediate setback as the piling & pile cap works, which was under a local contractor, were not taken up. “Stepping in quickly, we suggested an alternative,” mentions, Mohd Momin. “We convinced the client to implement the common raft method by avoiding pile caps and increasing its thickness so that the drainage line embedment could be accommodated within the raft, and thus avoid the basement structural screed.” This was a significant value addition. The building base was raised up to 1 m level with the finished floor level at 2.5 m height to mitigate the risk of deep excavation considering that the site was close to the sea.

Despite the two lockdowns, the project team completed the first milestone before schedule largely due to design improvisations and some smart work. “To accommodate both the 132 kV and 220 kV substations in the same building, the priming of OEL was strategic. We therefore proposed suitable building expansion joints to seamlessly integrate the work fronts,” shares Oscar. Other initiatives like designing a single GIB structure to accommodate 2 Ckts of 132 kV GIB and 1 Ckt of 220 kV GIB helped them to achieve their milestones.

For Mohd Momin, shrinking timelines, wherever possible, was key to catch up with the deliverables. Considering the pandemic situation, the team put in place a supply chain tracker for long-lead items which included the GIS equipment from Germany, transformers from Netherlands and batteries from Italy. “We made good use of digital applications to secure engineering approvals from various stakeholders through virtual meetings, organized online FATs, obtained dispatch clearances so that when the restrictions were lifted, we could accelerate across work fronts.”

Revamping a live network

The Rehabilitation and Upgradation of the Electricity Network of Hassi Berkine area in Algeria is a trailblazer project for PT&D where Project Director, Venkatesan Karuppaiah and team are on a mission to revamp the existing 220 kV power infrastructure in live conditions across 19 locations comprising 8 substations and 11 Central Processing Facilities.

Tracing the genesis of the project, Venkatesan recalls the considerable time spent at HQ Chennai to finalize the designs. “For over a year, the client was based at our Chennai Office working out the detailed design and execution plan before setting foot on this challenging terrain.” Several challenges awaited Project Control Manager, Shelbbyn Michael Raj at site. “Even getting to the work fronts was difficult as the alignment runs largely through the Sahara Desert with the nearest town located some 400 km from the site. From the beginning, we were escorted by an armed guard every morning to site that called for a great deal of planning to sequence the tasks.”

While the pandemic broke the workflow, digital applications enabled the team to complete 100% procurement through online/virtual FATs. “Majority of the materials were cleared from the port within the free storage period despite the stringent Algerian import regulations,” shares Venkatesan.

With the nature of this job very much like a hotline stringing, the onus was to ensure continuous power supply across three voltage levels – 220 kV, 60 kV & 30 kV that powered the oil and gas industries around this region. Sourcing the ‘as-built’ information from the two-decade old substations would have easily taken them around 4 months through conventional methods but by using 3D scanning and BIM, Venkatesan and team successfully firmed up the design deliverables in double quick time to fast track their works.

Their strategy was more of stage wise rehabilitation which involved deploying one set of 220/30 kV and one set of 220/60 kV mobile substation units to do the critical revamp works for the first set of substations and, thereafter, shift to the second and third set of substations. “At strategic junctions, we adapted the design to suit the infrastructure construction by proposing standalone buildings and in some cases even reducing the number of new structures,” adds Venkatesan. Having completed the engineering phase within the stipulated time, they have gained the client’s trust and are now keen to press forward. “Most of the composite works like laying 81 Km of 30 kV UG cable inside a hydrocarbon process facility have been completed and we are now aiming to finish the core infrastructure works by early 2022.”

Having set the base, the arduous task of laying the 33 kV cable weighing close to 20 Kg per meter at 6m height inside the tunnel and through the bridges is under progress. “It is a special project where the design parameters are very stringent calling for a high degree of precision as the fitting of the equipment inside the tunnel wall is being done considering the surface of dimension of the train. Added to this critical task, is the onus of ensuring safety during operations, shares, Planning Engineer, Tanmay Dwivedi.

Being a seismic zone under grade 5, it was vital to establish firm footings when executing the substation works. Since setting up a batching plant for concrete production was not feasible owing to the hilly terrain, the team networked with a local agency possessing the infrastructure and guided them to produce the approved concrete mix that not only hastened their construction of the portal works but achieved high quality standards.

Apart from the engineering scope, Umapathy’s initial onus was to quickly acquire the 900 acres required for the project. “It was perhaps the most challenging part, having to continuously follow up with various stake holders for clearance titles, especially for non-agriculture certifications from the National and State Highway Departments. Presently, with close to 85% of the land acquired, construction works for micro-piling, cabling, module mounting structure erection and other core activities are underway.”

While timelines are always stringent, it was more so for Umapathy‘s team as the project was bagged during the lockdown. “An extension of 5 months over the initial 18-month period has been the only saving grace though we have a range of works to cover and the only way forward is to bank on our EPC expertise and value engineering initiatives to bridge the gap.”

Several value engineering initiatives have fast tracked the project such as opting for pile foundation to do the invertor platform that has saved close to 70% of corresponding construction time, using structural steel for the superstructure that enabled them to complete the work 25 days ahead of schedule, optimizing the cable sizes through cyclic loading and thermal conductivity tests with simulation for enhanced conductivity and implementation of digital stores. “We have raised the solar operational effectiveness bar by type testing and getting the design clearance from NTPC for the country’s first 3150 A circuit breaker, sourced a suitable transmission line conductor to meet the current and voltage rating in line with technical recommendations and ensured the loading of the 33 kV HT cables aligning to the temperature and soil thermal resistivity.”

Today, the project is strategically placed with most of the prework done, thanks to some meticulous planning. “We have completed close to 90% of the engineering and plant design, lined up 75% of our procurement with key items like invertors, transformers, switch gears all based at our stores. Delivery of the balance modules along with transmission line materials are in progress and should be available by the time the groundwork is done.”