The natural habitats provide the basis for food and cash crops, fish stocks, forests, domesticated and wild animals and several other natural assets all of which benefit human society is a fact universally understood. Yet in the recent times, the unprecedented destruction and degradation of the natural environment has emerged as one of the biggest worldwide environmental concern. As the scale of most developmental activities has expanded, the adverse effects of these activities on natural habitats have become pronounced. The degradation of the physical environment, accelerating loss of large number of species and habitat alteration that lead to disruption of highly interconnected biological systems are only some of the irreversible threats that most developmental projects pose (Hildyard and Goldsmith, 1984; Gupta, 1988; Munasinghe, 1993 and Freedman, 1995).

The ecological impacts of linear expansion project are not only far more diverse but also outnumber the impacts associated with mega development projects. The expansion of existing utilities (airports, roads, railway lines, transmission and power lines) and the construction of new ones have been reported to cause ecological impacts of varying nature ranging from destruction of vegetal cover and fragmentation of habitats to disruption of migratory routes and even extinction of some species (Madder, 1984; Kuiken, 1988 and Anon., 1992).

In the southern part of British Columbia a number of airports lie along the route used by Canada Geese (Branta canadensis). The geese migrate in spring from the interior valleys of the Western United States to breed in the Yukon and Central Alaska. A similar situation occurs each spring in the Winnipeg region and involves lesser snow geese (Anser caerulescens) migrating North to their breeding areas around Hudson Bay (Edington, et. al., 1977).

Often new roads are usually justified on the grounds that they are supplementary to the existing overloaded roads. However, new roads are a source of disturbance in the sense that they provide greater accessibility which in turn will increase the uncontrolled exploitation of the forest resources. Species particularly at risk include the giant Brazilian otter (Pteronura brasiliensis) hunted for its fur, and a wide range of monkey species which are exported for medical research. The rare white-nosed saki (Chiropotes albinasus) is especially vulnerable because one of the new roads will bisect its only known refuge (Goodland and Irvin, 1957). The Pennsylvania Interstate 80, a four-lane highway passes through the forested area classified as oak-hickory (Quercus-Carya) forest. Observations have shown that during 18 months, 874 white-tailed-deers (Odocoileus virginianus) were killed due to accidents on this 313 mile long interstate highway (Puglisi, et. al., 1974). Another Interstate highway which intersects the eastern corner of the St. Martin Bay deer wintering area is in the Upper Michigan's Mackinac County. Yearly records shows that quite a few number of white-tailed deers (Odocoileus virginianus) got killed due to road accidents on this highway (Reilly, et. al., 1973).

Similarly transmission lines have also been reported to lead to mortality of avian species (Gyps copotheres) (Alonso, et. al., 1994).

Fragmentation of contiguous forest stretches supporting diverse faunal values has also been a major impact of road and rail expansion in several parts of India (Johnsingh, et.al., 1991; Chellam and Singh, 1994 and Pers. Comm. Ranjit Daniels, 1994).

A practical sustainable development option would perhaps permit improvement in the quality of life, allow renewability of resources and preserve resilience and richness of natural ecosystems.

1.1 PIPELINE PROJECTS AND ENVIRONMENTAL CONSIDERATIONS
Petroleum is an important but nonrenewable natural resource. Since, most of the wells extracting crude oil are located in the offshore regions or in the remote areas, transportation of crude oil from these wells to the refineries and subsequently then that of finished products from refineries to the consumption area requires an efficient mode of transportation. The most common mode of transporting petroleum products is oceanic tankers and pipelines. The total global pipeline network in 1982 for transporting petrol, other petroleum products and natural gas involved 64500 km and 13600 km respectively (Gilroy, 1983). The increasing rates of consumption and declining rates of production in most countries has led to expansion of pipelines for import of products from areas of production to areas of high demand. In 1988 Western Europe produced only about 8.3 * 1018 J of oil equivalent but consumed 24.9 * 1018 J, North America (United States and Canada) produced 22.9 * 1018 J but consumed 36.2 * 1018 J. On the other hand in contrast to this the Middle East produced the oil equivalent of 30.9 * 1018 J but consumed only 5.7 * 1018 J (Anon., 1990). This has resulted in the global expansion of pipeline network to 1,37,600 km (Ives, 1993).

However, there are chances that this mode of transportation may pollute the environment through accidental oil spills and by operational discharges (during cleaning of storage and ballast tanks of tankers). There have been some accidental spills, involving loss of large quantities of crude oil from disabled supertankers. Almost all earlier reported incidents of oil spills including the Arrow incident of Nova Scotia (11000 tonnes) in 1970, the Metula in Estrecho de Magallanes in 1973 (53000 tonnes), the Argo Merchant of Massachusetts in 1976 (26000 tonnes), etc. have caused severe ecological problems (Freedman, 1995).

Although the chances of accidental oil spill can not be totally ruled out, the pipelines are far more efficient and reliable mode of transporting the petroleum products when compared to the transportation by rail and road as the incidences of pipeline rupture or a well blowout are seldom. The causes of such accidents in the past have been diverse. They mainly included faulty pumping equipments and pipe seam welds, earthquakes, sabotage, etc. (Freedman, 1995). The number of incidents have now been on a decline with the availability of improved computer aided methodology for leak detection and for regular monitoring operations. As a result, expansion and upgradation of pipelines still remain the principal and most preferred task for the transport of crude and finished petroleum products.

On the contrary, there are substantial evidences of the ecological impacts of these pipelines which are otherwise least polluting and most efficient modes of transporting petroleum products and natural gases (Dean, 1984 and Anon., 1993a). Our earlier experiences of pipeline project related assessments have further substantiated the fact that, these projects, can lead to alterations in the wilderness values of natural habitats both in terrestrial and aquatic ecosystems (Rajvanshi, 1995).

The proposed Bombay - Manmad Pipeline Project would enable the shifting of nodal point for loading of petroleum products from Bombay to Paniwadi near Manmad. The pipeline route would traverse through the forested areas of Shahapur Forest Division. These forest areas supports not only mammalian species such as leopard, jungle cat, striped hyaena, barking deer, nilgai, four horned antelope, etc. but also harbours a diverse avifauna. The proposed development activity is likely to disrupt the local movements of these wild animals and their normal life cycle (Anon., 1995).

The proposed Jorhat - Numaligarh Pipeline, which would cater to the need of crude oil of an upcoming refinery at Numaligarh, would traverse through Dhansiri river. Dhansiri river, a tributary of river Brahmaputra, supports a small group of migratory Gangetic dolphin (Platanista gangetica) and otter (Lutra sp.). Both these species are listed in red list of threatened animals (IUCN, 1994). The Gangetic dolphin has its distribution confined to only Ganges and Brahmaputra rivers, whereas the otter has a wider range of distribution. Any construction related activity of the proposed project if carried out during the monsoon season and post monsoon season, in Dhansiri river would have an adverse impact on both these species (Anon., 1995).

A 25 km stretch of the proposed Hajira - Bijaipur - Jagdishpur Gas Pipeline would traverse through the proposed Pohri Great Indian Bustard Sanctuary. This is one of the most important Great Indian Bustard habitats in the country, supporting a small population of this endangered species (Anon., 1993). Protection of this sanctuary is therefore critical for conservation of bustards in the country.

Determining the environmental effects of any developmental project or policy is the fundamental step towards incorporating environmental concerns into development planning and outlining the remedial strategies. Environmental Impact Assessment (EIA) is therefore, potentially one of the most valuable tools that provides ecological and economic assessment of proposed developmental expansions.

1.2 PROPOSED PROJECT: OMAN - INDIA GAS PIPELINE PROJECT
Oman Oil Company Limited (OOC), a joint venture of the Oman Government and an international oil company, proposes to lay a subsea pipeline traversing the Arabian Sea to connect the natural gas reserves in Oman with the markets in India.

Under this proposal the Government of India would receive 28.32 MMSCMD (Million Metric Standard Cubic Meter per Day) gas from the gas fields of Oman. The gas after conditioning and metering at the gas production facility at Sayh Rawl, in Oman would be transported through 380 km onshore pipeline to compression station at Ra's Al Jifan, Oman. From here, the gas would be transported through 1139 km offshore pipeline to India. The landfall point in India is at Rapar Gadhwali in Kachchh district. After reducing the gas pressure at pressure reduction station at Rapar Gadhwali, the gas would be then transported through a 165 km onshore pipeline to the custody transfer metering station at Bhachau, India (Fig. 1.1).

1.2.1 Project profile
The proposed project has two phases. In Phase - I, route selection procedures have been completed, whereas the actual construction activity would be carried out in the Phase - II. The total length of the proposed pipeline onshore in Oman region is 380 km, whereas the total length of the onshore pipeline in Indian region would be approximately 165 km. The total length of the proposed offshore pipeline in the Arabian Sea would be approximately 1139 km.

The inner diameter of the proposed pipeline from landfall point to pressure reduction station at Rapar Gadhwali would be 61 cm, the outer diameter of the proposed pipeline from Rapar Gadhwali to Bhachau would be 102 cm. The material used for this proposed project would be as per the API 5L * 70. The pipeline would be buried minimum 1 m below the surface level.

The proposed pipeline route would not traverse through any perennial river. Almost all the rivers and nallahs en route the proposed pipeline route are seasonal water courses. Hence, no specific method such as Horizontal Directional Drilling (HDD) would be adopted to lay the pipeline.

The major crossings en route the proposed pipeline are as follows:

Road (metalled) : 15

Road (non - metalled) : 70

Railway lines : 5

Major rivers : Nil

Minor rivers : 8

Small water streams : 83

1.3 OBJECTIVES OF THE EIA STUDY
Based on the successful completion of the Phase - I, the OOC initiated Phase - II of the project. In Phase - II the Engineers India Limited (EIL) was awarded the job for Pipeline Application Engineering (PE) for the Onshore India Facilities. Since environmental appraisal of development project has become a mandatory requirement of the Ministry of Forest and Environment (MoE&F), Government of India, a comprehensive EIA study is required to be undertaken prior clearance of such projects.

1.4 SCOPE OF WORK
Engineers India Limited (EIL), New Delhi offered a consultancy to the Wildlife Institute of India (WII), Dehradun for undertaking the environmental impact assessment studies for the above project with special reference to impacts on wildlife species and their habitats.

The broad scope of work under the consultancy offer to Wildlife Institute of India would include the following:

• assessment of the status of wildlife species and their habitats (terrestrial and aquatic) within the proposed pipeline corridor.
   

• identification and evaluation of the likely impacts of the project on wildlife species and habitats.
   

• outlining of the mitigatory measures for the likely impacts that may be caused by the proposed project.
   

• outlining of the legal and statutory obligations to be fulfilled by the project proponent under the Wildlife (Protection) Act, 1972; Forest (Conservation) Act, 1980; and Environmental Protection Act, 1986.