Our past experiences of development of forest based industries and hydro-electric projects in the state of Assam offer enough examples of project induced extirpation of some of the finest wildlife habitats. This has placed greater thrust on careful evaluation of the impacts of proposed development projects, no matter, how small they are. Impacts of developments in the energy sector are considered to have spatial and temporal attributes and it is for this reason that energy related developments are listed under Schedule - I industries in the Environmental Impact Assessment Notification of MoE&F, 1994 (Anon., 1994c).

An ecological assessment of the proposed hydrotreatment plant in the BRPL complex at Bongaigaon therefore commands greater importance and justification. An assessment of the project related impacts on the biological environment has been attempted here. The preceding section of this report provides substantive information on the biological richness of the project area. It is further ascertained from the ecological studies that the aquatic and terrestrial wildlife habitats in the project environment outside the BRPL complex have special significance as these support diverse avian communities and some of the highly endangered species like the Golden langur and the Indian pangolin. Both these species are listed in Schedule - I of the Indian Wildlife Protection Act, 1972 (Anon., 1972).

Destruction of forests and wildlife habitats for proposed developments, changes in human activity patterns, expansion in infrastructural services and elevation of pollution levels are some of the perceivable impacts of the development upon the quality of wildlife habitats and their values.

Based on the overall plot plan of the proposed hydrotreatment plant, it is evident that the development would be confined to a plot area of 80m X 78m in the existing complex of M/s BRPL, Bongaigaon. The plot surrounding already has developed road network and other essential infrastructural support including the hydrogen source, tank farm, utility block, Control Room, Crude Distillation Unit (CDU) and Delayed Coker Unit (CDU). No significant impacts are therefore foreseen from works involving land preparation and construction activities involved in developing the site for proposed hydrotreatment plant at Bongaigaon.

The BRPL complex which has been in existence since the year 1973, now has a well developed township including housing and recreational facilities for its employees and also well developed infrastructure for utilities. The proposed expansion does not envisage changes either in the human activity pattern or in the infrastructural expansion.

The discharge of atmospheric emissions, cooling waters, waste heat and liquid effluents are potential cause of significant impacts. The primary sources of gaseous pollutants are stacks, storage tanks and pump house. The undesirable gaseous emission from a stack is sulphur dioxide. The fuels proposed to be used in the furnace of the hydrotreatment plant are fuel gas generated in the refinery and some quantities of internal fuel oil. These fuels are expected to have very low sulphur content and as such the sulphur dioxide content in the stack gases is expected to be lower than the permissible limits. Accordingly based on the commitments of the authorities of M\s BRPL, to use superior quality fuel in the furnace, the `no objection' certificate has already been issued by Assam State Pollution Board to set up the hydrotreatment plant.

The effluents of the BRPL refinery drain into a small rivulet - the Tunia nala, originating from within the BRPL Complex. This ultimately join the Tunia river. This river after passing through the outskirts of Bongaigaon township becomes a major receiving waterbody for municipal sewage, waters from railway colony and workshop and the effluents from several small industrial units. These several pollutant sources have greatly reduced the potential of this river as a wetland habitat. This is even evident from the list of birds sighted in Tunia river (refer Table 6 in the preceding section of this report). This represents an unusual scenario of environmental deterioration remaining confined to a single waterbody in the project area.

The liquid effluent generated in the hydrotreatment unit would be treated in the existing Effluent Treatment Plant of the refinery, which is being augmented and modernised by providing a Tertiary Treatment Plant with the ultimate objective of recycling the treated effluent leaving no liquid effluent discharge outside the complex. The proposed hydrotreatment plant is therefore not likely to further elevate the pollution levels of the Tunia river.

All the other wetlands that enjoy the status of good aquatic habitats (Aie and Kujia rivers and Naodora, Bhosamari, Paropota and Kasorani lakes) are not likely to be affected by the proposed expansion.

It has become fully understood now that forests and wildlife habitats outside the Protected Areas are particularly critical for the survival of non human primate species like Golden langur that have become highly threatened on account of shrinkage in their existing habitat ranges. Destruction and diversion of forest areas for development of projects site is a single largest threat to the survival of Golden langur and most other species in the area. Since the proposed project does not envisage cutting, clearfelling or diversion of any forest area for the project, no impacts resulting from physical destruction of habitats are foreseen.

The only other impact could result from the elevation of ambient temperature. There are reports of wildlife being impacted upon by high ambient temperatures around industrial establishment (Newman, 1979). This could not be however established in the given time frame for this study as this would require long term observations to perceive behavioral and physiological changes in the animals in the vicinity of the proposed development.

Although the proposed expansion within the existing complex of BRPL is not expected to have significant impacts on the ecology of the area, the authorities of M/s BRPL still owe their special debts to the natural resources of the region that have withstood the impacts of establishment of a refinery for over two decades. They have greater responsibility to restore environmental quality and secure environmental protection. Use of advanced technology, for waste disposal and treatment and a firm commitment to implement an effective environmental management plan should be the mandate of the project authorities. The project authorities should also give firm commitment to monitor the air and water quality of the region and based on the trends should accordingly develop preventive and ameliorative safeguards.