DPR and Evaluation of EIA Study for
Sethusamudram Ship Channel Project

by

       L&T Ramboll Consulting Engineers Limited,

       339/340, Annasalai, Nandanam, Chennai-35

Executive Summary

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Project Background

India has a peninsular coast of 3554 nautical miles and has had maritime trade with various countries of the world since time immemorial.  Also shipping trade between the east and west coasts of India has prevailed for a long time.  But the coast of India does not have a continuous navigation channel connecting the east and west coasts.  Currently the ships coming from the west coast of India and other western countries with destination in the east coast of India and also in Bangladesh , China etc. have to navigate around the Sri Lanka coast.  The existing waterway is shallow and not sufficient for the movement of ships.  This is due to the presence of a reef, known as Adams Bridge , located south east of Rameswaram near Pamban, which connects the Talaimannar Coast of Srilanka.

In order to reduce the steaming distances between the east and west coasts of India and to improve the navigation within the territorial waters of India a number of proposals were considered to cut a ship channel called Sethusamudram Ship connecting the Gulf of Mannar with the Palk Bay.

In this context, Government of India appointed Tuticorin Port Trust (TPT) as a Nodal Agency for developing the Sethusamudram Ship Channel Project (SSCP) and entrusted the work of Preparation of Detailed project report to L & T-RAMBOLL Consulting Engineers (LTR), Chennai.

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Data Collection and Review

As many as nine pre independence proposals (between 1860 and 1922) were formulated for cutting a Channel across the narrow strip of land mostly through the Rameswaram Island to connect the Gulf of Mannar with Palk Bay .  Post independence proposals such as Sethusamudram Project Committee – 1956; Nagendra Singh Committee Report (1967) (C.V.Venkateswaran);  Lakshminarayana Committee Report (1981);  Pallavan Transport Consultancy Services Report – 1996;  National Environmental Research Institute (NEERI) Reports(2004) are reviewed and discussed in this report.

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Project Site Environment

Sethusamudram Ship Channel is proposed to be constructed connecting the Bay of Bengal to the Gulf of Mannar through a dredged channel on either side of the Palk Bay .

The nearshore to the western side of the Rameswaram Island is found to be very shallow causing the Northeast monsoon waves to break far offshore.  The coastal stretch in Palk Bay shows the presence of wide beach with elevated dunes.

Data shows that the climate along the entire length of the channel is similar, with October to December being the rainy season, while May to August is the hot season.  However, Adiramapatnam in the Palk Bay received a substantial amount of rainfall during the months of August and September, indicating that it is influenced by both the NE and SW Monsoons Wind speeds are higher in June, July and August during the SW monsoon, in which a significant percentage of the observations are in the range of 8 to 10 m/s.  The analysis also shows most frequently occurring wind speed class being 6-8 m/s.  The analysis also shows most frequently occurring wind speed class being 6-8 m/s during the NE monsoon in the months of November and December.  The predominant wind directions are SW, WSW during Southwest and NE during the Northeast monsoon seasons respectively and these account for nearly 45% of the observations.

It is observed that offshore wind speed in the vicinity of Palk Bay exceeds 5 m/s for 76 days in a year while that exceeding 10 m/s is only for 9.2 days.

In about 150 years, a total of 44 storms (depressions, cyclones and hurricanes) have passed within a radius of 200 km from Pamban during the period 1842-1995, while the corresponding number around Point Calimere is 60.  Most of the storms occur during the period October to December, while there are no storms during the SW monsoon season.  The maximum reported wind speed is 130 knots, which is estimated during the severe cyclonic storm of December 1964, which is crossed close to Pamban. 

From the wave analysis of offshore data it is evident that off Palk Straits, the waves are in the range of 0.5 to 1.8m with periods between 3 to 7s.  During the pre SW monsoon the waves are from SSE, SE and South directions with annual percentage of 25%. However during the SW monsoon these are predominantly from SSW, SW and West with annual percentage of about 37%.  Whereas, during NE monsoon the predominant wave directions are NNE, NE and ENE.  The waves from these directions cover 29% of the annual wave climate and 76% of the wave climate during the NE monsoon (November – February).

The tidal ranges of Rameswaram facing Gulf of Mannar , experiences a current in westerly direction throughout the year, except in June and July.  Although the longside current was extremely weak along the sand spit facing Palk Bay , it tends to be easterly during Southwest monsoon/fair weather period and westerly during Northeast monsoon.  The surface current velocities reported were as mild as 0.2 – 0.4 m/sec except on a few days during the south-west monsoon when it rose upto 0.7 m/sec.  The directions of the currents were found to follow the directions of predominant winds during the observations.

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Review of Earlier Alignments

The canal layout suggested by NEERI was reviewed from technical requirements and to minimize dredging quantities and recommended with  minor changes to geographical co-ordinates of turning points to minimize dredging quantities and design of Channel bends as warranted from navigational considerations.

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Field Survey and Investigation

Field measurements of waves and currents in the vicinity of the proposed Channel are presented in the “Report on Sea state” prepared by NSDRC.  Wave data collected using a wave rider buoy deployed off Vembar in the Gulf of Mannar , for a period of one year during March 1997 to February 1998. This shows Hs varies between 0.4 and 1.5m and Tz varies between 3 and 9 sec.

Current observations have been carried out at four locations, during three seasons for a duration of two days in each season.

Results of the analysis shows that during SW monsoon, the average current speed at the surface and bottom were 0.2m/sec with maximum being 0.3m/sec. During NW and fair weather season average current values were 0.1m/sec.

Geotechnical data to determine the nature of the soil parameters below the seabed has been obtained at three locations in water depths of 2, 3 and 5m in the Adams Bride area using jet probe drilling.

Suggestions for further studies / Data collection

For the purpose of preliminary design of the channel and to carry out further studies to finalise the channel alignment, design parameters in respect to the following Met – Ocean parameters are essential.

• Wind speed and direction.

• Wave height, period and direction.

• Current speed and direction.

• Tides and Water levels.

In order to arrive at reasonably accurate estimates of capital dredging, it was suggested that the following additional surveys and Investigations be carried out along the alignment of the channel.

• Bathymetry Survey

• Sub bottom profiling

• Geotechnical borehole investigation along the channel totaling up to 50 numbers.

• A comprehensive modeling exercise to study wave transformation and breaking, flow pattern caused by breaking waves, tides and wing and resulting sediment transport pattern be undertaken for both the Adams Bridge region and the Palk Straits region.

• It was also recommended to conduct a ship navigation simulation study.

Field Surveys and Model Studies Reports.

Tuticorin Port Trust has since carried out Marine Geophysical Studies (National Institute of Ocean Technology) and Mathematical Model Studies (Indomer-Alkyon) in 2004-2005. Tuticorin Port Trust also carried out Vibracrore investigations at 44 locations along the channel alignment and 4 boreholes investigations at Adam’s Bridge . The finding s of these studies and investigations have been discussed in this Report.

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Traffic Forecast and Vessel size Analysis

GDP method of traffic projection is considered appropriate as traffic of SSCP is related to the growth of GDP for the country as a whole rather than the developments in the immediate neighborhood of the channel. Following methodology is adopted.

• Questionnaire survey

• Study trend in GDP

• Traffic study of major ports

• Portwise cargowise traffic projections for all major ports using GDP method

• Vessel size analysis

• Potential Vessel traffic projection for SSCP

• Restricted Vessel traffic projection for SSCP

• Checked Vessel traffic projection with actual 203-04 data

A detailed vessels size analysis has been carried out and typical dimensions of the design vessel sizes are given below.

      * draft restricted to 10 m

After careful consideration of the channel parameters, it is recommended to consider 10 m draft vessels to pass through the SSCP channel. Even though the world-wide trend indicates the preference for building larger vessels, there has been an increase about 5% annually, in the number of vessels of size up to 30,000 DWT during the last 20 years. Also, with this draft restriction of 10 m in the SSCP, there could be a growth in number of ships specially built for the purpose of passing through SSCP, may be called ‘SEHTU MAX’, similar to vessels being built like Panamax or Suez max vessels after the development of Panama and Suez canals.

From the vessel size analysis, all vessels up to 20,000 DWT, about 75% of 30,000 DWT, 10% of vessels up to 40,000 DWT and 5% of vessels upto 50,000 DWT, and all empty vessels will fall in this category and can pass through SSCP. This traffic is further adjusted to account for downtime predicted by the model studies and is considered for planning and financial analysis. Total traffic through SSCP is presented in the table below:

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Preliminary Design and Phasing

• The channel is designed as a two-way channel for the dimensions of the design vessel, having a speed of 8 hnots. The depth of channel is maintained at -12m CD and bottom width of channel is 300m.

• By adopting a minimum sight distance of 2.5km for the SSCP (same as that of Panama Canal ), minimum inter arrival time between ships required is 10 minutes (for vessel speed of 8knots). The inter-arrival time for the year 2025, works out to 90 minutes, is well above this minimum limit. So with two-way channel, the year 2025 traffic can be handled without any congestion.

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Identification of Dredging Requirement

The dredging quantity estimation is done taking sections at every 100m interval and integrating over the length of segment. The details of channel and dredging quantities computed for each segment are as below.

Based on the model studies report, it is estimated the maintenance dredging to be 2 million cu.m in the first year reduction to 1.4 million cu.m in 5 years and remaining constant thereafter.

For dredging in Adam’s Bridge upto a level of (-) level, it is proposed to deploy CSD. Dredging below the level of -8, upto -12, will be by TSHD, except in region where dense / hard material is encountered where again CSD will be used.

The Palk Strait area is divided into two sections depending on the distance to the dumping spot in Bay of Bengal (one with average lead of 60 km and the other with average lead of 40 km) where dredging will be carried out using TSHD.

The dredged materials from Adam’s Bridge area is proposed to be dumped off-shore into sea in the Gulf of Mannar at location of 20-30 m natural depth within Indian territorial waters. The dumping location is assessed to be 25-30 km away from Adam’s Bridge . The entire quantity of dredged material from Adam’s Bridge can be dumped at this site. As and option, about 8 million cu.m is proposed to be used for degraded areas in Pamban island.

The dredged material from Palk Strait is proposed to be dumped offshore in Bay of Bengal area at about 25-30 m depth.

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Ancillary Facilities

Buildings : By the start of the project and later on for administrative and operational purposes, an administrative building complex having a plinth area of about 1000sq.m and field office complex of 500 sq.m with amenities and security cabins are recommended at accessible locations at Rameswaram / Pamban / Mandapam.

Service Jetty : Two service jetties one each at Dhanushkodi and Point Calimere will be provided in 5m water depths.

Shore Facilities

At the root of service jetties on the reclaimed land, it is recommended to construct the repair Workshop complex of 1000 m² and the Buoy Yard of 7500m² with access facilities such as a two lane road and railway sidings.

Development of Fishing Harbour

The fisheries Harbour at Rameswaram may be developed to modem requirements with fish landing stations and augmenting shore facilities for auctioning etc. as social development measure.

Two more fishing harbours may also be developed in the region, with the possible assistance of the State, in identifying specific locations.

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Vessel Traffic Management System and Navigational Aids

It is recommended to provide VTMS for the SSCP operations. In view of deeply dented coast with attendant range issues, provision of 4 VTMS towers are minimum for reliable coverage. 4 number RCC VTMS towers are provided with fittings and four floor configuration to cover housing the VTMS equipment, microwave communication link and tracking equipment, Channel Control Towers (CCTs), AIS, Security, power supplies, meteorological and hydrological instruments, and logistic needs. Two towers are located onshore at Rameswaram Island and Point Calimere and two offshore locations close to the Channel turning points in positions. (D&E)

The navigational aids will play a crucial role for safe passage of vessels through SSCP. The important navigational aids are as follows.

(a)  VTMS

(b)  Navigational buoys as per IALA system-30

(c)  DGPS reference station at Rameswaram and Point Calimere +2 Fairway buoys to provide high and CCTs accuracy positioning for vessels.

(d)  AIS (as per IMO SOLAS convention, regulation 19, subsection 2.4.5) as part of VTMS

(e)  Set of legally valid navigational charts and publications, based on detailed hydrographic surveys, for marine safety, published by the National Hydrographic Office under IMO/IHO conventions.

     Flotilla

With due regard to the navigational safety vis-à-vis type of vessels and weather conditions in the area, the minimum requirements are as follows.

Note : All SSCP crafts will have emergency support facilities and 10 Ton BP tugs will have oil pollution cleanup equipment.

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    Environmental and Social Impact Analysis

During the year 2002, Tuticorin Port Trust (TPT) appointed National Environmental Engineering Research Institute (NEERI), for carrying out Rapid & Comprehensive Environmental Impact Assessment Studies along with assessing Techno-economic viability, Oceanographic Studies for the proposed Sethu Samudram Ship Channel Project. (SSCP)

The impacts predicted by NEERI were evaluated and subsequently an Environmental Management Plan has been prepared in this Report. The Environmental Management Plan covers the implementation & operation phase of the SSCP.

The impacts addressed by NEERI on environmental and social front and also the impacts associated with the development of the land-based facilities have been evaluated in this DPR for pre-construction, construction and operation phase of SSCP.