TWO WET IC PROJECTS REMAIN FOCUSED ON DELIVERY & PROFITABILITY

SURYA WATER SUPPLY SCHEME

The Surya Regional Water Supply Scheme involves the construction of a 707 MLD Intake Well from where the raw water is lifted at the Kawadas pickup weir (downstream of the Surya dam) and pumped through a 2.2 m dia. MS pipe for 2 kms to reach a 419 MLD Water Treatment Plant (WTP) at Surya Nagar. Post treatment, the water is pumped through another 2.2 m dia. MS pipe for 0.6 kms to reach the Break Pressure Tank (BPT) which provides the required head for transmitting water through gravity flow via another underground 2.2 m dia, 56-km-long MS pipeline and through the
1.7 km Mendhwankhind Tunnel to reach the 38 ML Master Balancing Reservoir (MBR) at Kashidkopar for further distribution to the Vasai-Virar City Municipal Corporation. Water is also diverted at the Kashidkopar location and clear water supplied through a 21 km MS pipeline (1.8 m dia) and through the 4.6 kms Tungareshwar Tunnel to reach the
45 ML MBR at Chene for further distribution to the Mira-Bhayander Municipal Corporation.

However, with Stage-I clearance, pipeline works commenced and were streamlined under police protection. Stage-II clearance was another long, drawn-out affair with delays owing to issues related to the Old Surya Dam but finally secured a year later in October 2019, thanks to the team’s determined efforts and consistent follow ups. Key structures like the WTP & 10.2 km pipeline fall in the Dahanu Taluka that required permission from the Dahanu Taluka Environment Protection Authority (DTEPA) and although the team received the requisite go ahead, it was again long delayed due to the non-appointment of the authority’s Chairman!

As the permissions were ‘extracted’, the team faced opposition from the local villagers for the construction of both the WTP and the reservoir at the Kashidkopar MBR and civil work could only commence under massive police protection. No sooner had the team got into action, they were broadsided by the pandemic that disrupted all their well-laid plans.

Facing & overcoming a plethora of technical challenges

Each of their activities were fraught with challenges. For the intake works, the team discovered that the water level in the Kawdas Weir remained constant all year round. “We did not have a dry period and constructed the coffer dam in water of 9 m depth, dewatering at 10 m depths,” says Akhilesh Singh, Construction Manager (Civil), seriously. Exposed rock was available only at 85 m levels and excavating hard rock for the intake well at 30 m depth was tough, as was excavating in the vicinity of the existing dam and pump house. The team control blasted taking all the necessary safety precautions to expedite progress, though vehicular movement, and machinery operation for various activities in slushy, wet and windy conditions was a nightmare.

In the WTP works, concreting the BPT wall during slipform movement, BPT roof slab at 30-m height was difficult too owing to the altitude and high wind speed as was formwork and concreting the pumphouse roof slab at 10 m height on a complicated filter bed. The team successfully overcame these challenges to complete the 15.5 m tall BPT wall in just 72 hours.

More challenges awaited the team underground after they conducted extensive geotechnical investigations up to a depth of 200 m at the Tungareshwar Tunnel. “We constructed a 55-m deep inlet shaft in extreme hard rock, a back shunt of up to 50 m and a front shunt up to 10 m both using the drill blast method,” reveals Akhilesh, “and the entire tunnel in a single drive of 4.6 km at a depth of 55 m,” he adds with vigour. The water tunnel was constructed using the segmental lining method. Almost the entire pipeline terrain was challenging with hard rock encountered at 1 m below ground level. Laying the MS pipeline involved controlled blasting of extremely hard rock along an active national highway, facing collapsible soil in several areas, when constructing the coffer dam for the river crossing and managing highway & railway crossings.

Value engineering profitable progress

“By proposing a Common Finished Internal Diameter of 2.85 m for both tunnels, we utilized our resources better, saved time, increased productivity, and saved the cost of buying a new TBM and specific materials,” remarks Colin, with a satisfied look, adding, “There was a significant improvement of 32% in advance rate in the Tungareshwar drive over the Mendhwankhind drive, that was wholeheartedly appreciated by the customer.” The proposal to reduce the encasement thickness of the MS pipeline from 300 mm to 200 mm for the 11.6 km of NH encasement that was duly vetted by IIT Bombay and accepted by the Customer, resulted in nearly 30% less RCC works with other obvious benefits.

Initially, the specifications were mandated for a PCC bedding before laying the MS pipes. The team were proposed a granular graded material instead for a pipeline stretch of 80 kms as the strata was mostly weathered or hard rock that significantly increased productivity and eased execution along with cost savings. Opting for precast concrete segmental lining instead of RCC in-situ lining for both tunnels translated into significantly faster cycle times and improved the productivity of tunnel boring.

Using advanced construction methodologies to fast-track activities

“Using slipform methodology for wall casting at the intake and BPT improved productivity, saved approximately 2 months and allowed us to work through the monsoon since we completed the outer walls prior to the onset of the rains,” points out Assistant Construction Manager (MECH), Ashutosh Shukla.

Opting for hollow core slabs instead of cast in situ for the master balancing reservoirs and clear water reservoir served the team well while using mobile formwork to construct the MBRs appreciably reduced cycle time and increased productivity. Flux core arc welding for field joints of the MS pipeline instead of the traditional method of shielded metal arc welding has shown promising results with improved product quality and approximately 50% better productivity. Another smart ploy has been to use a Mechanical Screener to sieve excavated soil below 10 mm size for bedding & backfilling the pipeline trench that improved productivity by a whopping 8 times.

Engineer (MECH), Jitendra Thombre Prakash is glad that IoT devices have enhanced the efficiency of their project that is spread across 80 kms, alongside a highway. Assistant Construction Manager (CIVIL) – Planning, Surajit Mondal adds, “Fuel sensors have been installed on more than 50% of the assets, diesel dispensing is being monitored by an RFID- based. system, the first of its kind, and diesel distribution is through an automated FDMS system.” While e-Pragathi tracks project progress, real-time asset monitoring is through a web portal and a mobile application called SPOTRACK, accessible to all key stakeholders.

Although the team has achieved a lot, there is still some distance to go before delivering their project. “Bulk water supply of 218 ML to Mira Bhayander Municipal Corporation and 27 villages in Vasai-Virar City Municipal Corporation area covering some 16 lakh people is planned by end May 2024,” shares Colin. Testing, trial runs and commissioning are also planned by then, and going by their track record, there is no doubt that Colin and his team will certainly deliver.

GANGADHAR MEHER LIFT IRRIGATION PROJECT

The Gangadhar Meher Lift Irrigation Project, awarded in March 2021 by the Department of Water Resources (DoWR), Government of Odisha, involves constructing an intake structure with pressure main from RD 0.00 Km to 34.10 Km along the right bank of Bargarh Main Canal (BMC) on an EPC turnkey basis, including a power connectivity system and O&M for 5 years. The project envisions to meet the irrigation needs of 25,600 Ha upland areas in the districts of Bargarh and Sonepur. Project Manager, Rajasekar S, can afford to smile at the progress and profitability of his project.

After searching the entire stretch of the pressure main alignment, the project team finalized land for the fabrication yard in the middle of the alignment that reduced the cost of shifting the pipes and additionally, identified government lands in close vicinity to stack them. With the pipe fabrication yard located away from the nearby villages, the team was free to work smoothly without any local hindrances. The pipe fabrication and coating works commenced in top gear in two shifts, and they completed the work two months in advance. The factory licence and statutory approvals too were obtained by the site team on time.

Sudarsan Dutta, Assistant Construction Manager (Civil), is thrilled at the appreciation from the client and consultants for the automated process of applying food grade epoxy coating inside and coal tar epoxy coating outside the pipes that have saved them considerable time. “We completed the pipe fabrication and coating works 2 months in advance against the planned target,” he shares with a thumbs up, “that gave us the confidence that we could complete this project on time.”

Timely mobilization of resources

All the resources like workmen, materials, and machinery, including higher-capacity cranes for pipe laying works, have been speedily mobilized, keeping the project on track. “The pump, motor and electro-mechanical materials were procured on time,” states Syed Najaf Hussain, Assistant Construction Manager (Planning). “In fact, we unloaded two
20 MVA transformers directly onto a pedestal to save time and avoid possible damages.”

“In some locations, we dug 8 m wide x 0.6 m deep trenches in advance before cultivation to lay the pipes that helped us to smoothly complete around 9 km of MS pipe laying,” mentions a beaming Saleem Raza, Construction Manager (MECH).

Delighted that his team has ensured timely payments from the Client to maintain a positive cash flow, Rajasekar sums up. “We have completed 93% of the project as of July 2023 thanks to our careful planning, precise and timely mobilization and procurement, and effective stakeholder engagement.” He is equally glad that the Chief Secretary, Additional Chief Secretary, Engineer in Chief (DoWR) and other government officials who visited the pumphouse and pipe yard locations have appreciated for the project team’s efforts. With just finishing touches required, the team is well on their way to deliver a winner!