L&T GEOSTRUCTURE NRL PROJECT OFF TO A GREAT START

Numaligarh Refinery Limited (NRL), Assam, intends to expand its crude oil processing capacity from the present
3 MMTPA to 9 MMTPA, as part of India’s Hydrocarbon Vision 2030 to help meet the growing demand for petroleum products. The project offers huge scope for piling and ground improvement works. After extensive risk assessment to quell the initial skepticism of venturing into business in the North-East, L&T GeoStructure (LTGS) took up the mandate for piling and GI works at Numaligarh. The project that was awarded on December 12^th 2021 involves 2,989 piles of
750 mm dia, 20 m and 25 m in length, 12 initial load tests, 17 routine load tests each for both vertical & lateral and a further 17 pull out tests and 8,000 stone columns, 900 mm in dia and 12 m in depth.

A job well begun is half done

Off to a good start, the project has made significant headway having achieved the milestone of 1,000 piles in August 2022. The 750 mm diameter piles, averaging 25 m in depth, were cast in a short span of 5 months hitting a maximum of up to 16 piles per day, with 4 hydraulic piling rigs and 3 cranes deployed for the piling works.

Despite being in a remote location, Project Manager, Nowshath Hussain is happy that the entire site mobilization was completed within a month. “This area experiences rains throughout the year with heavy rainfall during the monsoon period,” he informs. “To ensure uninterrupted access for the movement of machinery, especially transit mixers and dumpers, we have used fiber-type Porta Mats. Such methods and proper coordination with the local concrete supplier, have ensured that our supply of concrete has never been affected,” he adds.

The good news for Planning Manager, Nikhil Pasari has been that the design team set the ball rolling with some quick GTI and test pile designs. “They demonstrated their technical prowess with all site load tests,” he remarks.“All the initial pile load tests were successfully completed to the complete satisfaction of our client, that enabled us to conclude the design quickly and ensured continuation of working piles without any delays,” he says, with an air of achievement.

Addressing local issues to ensure progress

Harmonizing with the locals is a key differentiator for progress because the area has a strong presence of unions.“We formed a co-ordination committee to address all concerns of the unions,” shares Construction Manager, Subrata Ray. “Sub-contracting works like reinforcements and piling were distributed among the locals to meet their employment needs, thus contributing to their livelihood and overall development.”

“In fact, LTGS has engaged several budding small contractors to give them the opportunity to do pile cage fabrication works,” interjects Nowshath, “and this inclusiveness of external agencies has ensured unhindered work progress.”

Planning & executing to succeed

A strict monthly material procurement plan has been followed for continuous tracking of basic piling consumables to ensure uninterrupted supply and steady progress. The spiral bending machine has been deployed for making the pile cage master rings, with 16 mm dia TMT, that reduces the time required to bend one master ring from 10 mins to 40 seconds. “Such practices have improved our productivity and ensured that we always have sufficient stock of pile cages,” reminds Nikhil. To ensure a smaller ecological footprint, polymer fluid has been used as drilling fluid to stabilize the boring, that is economical to dispose of and helps keep the site tidy.

All the piles are installed by taking utmost care of pile quality. “We have already conducted 21 pile load tests (7 each of vertical, lateral and pull-out tests) within 4 months and the results have been extremely satisfactory,” shares a pleased QA QC Lead – Ritabrata Roy. More than 11,000 cum of concrete has been completed till the date, and all concreting is completed within 6 hours of boring completion, although there are many entry and exit security protocols to be followed in the refinery premises. “Till date, we have not received any NC or major observation from the client, and they are extremely satisfied with the quality of product delivered by LTGS,” adds Ritabrata for good measure.