The DHPU envisages meeting the requirements for improving fuel quality with respect to Sulphur content, cetane number and consequently reducing aerial emissions and pollution load of receiving streams and enhancing the capacity of the refinery for the production of superior petroleum products. The proposed project is thus seen as a positive step in the improvement environmental quality through enhancement of product quality and augmentation of refinery capacity. For the consideration of spatial and temporal attributes of the stress associated with the proposed project, the following project characteristic establish low impact potential of the project in generating ecological stress.

Location and Size

Based on the Overall Plot Plan (Appendix I) of the proposed DHPU, it is evident that activities associated with this development confined within a plot area of 80m x 78m in the existing complex of M/s BRPL, Bongaingaon will be fairly limited in its spatial dimensions.

Sources of Emission

Since the fuel to be used for the proposed project is sweet fuel gas with minimum use of fuel oil and the fuel gas generated in DHPU shall be consumed internally, transport of undesired emission into the atmosphere are unseen. A new hydrocarbon flare system and a new acid flare system have been considered for the proposed project to further reduce the impacts of unburnt gaseous products arising from the project operations. With the reduction in the sulphur content of the diesel and a setting up of the sulphur recovery unit to recover the solidified sulphur from the liquid sulphur, the possibility of increased sulphur dioxide content of the emissions dispersing in the ambient environment is likely to be reduced even below the existing ambient concentration of oxide of sulphur from the plant reported by the project authorities in the previous year (Appendix VI).

Discharge of Liquid Effluents

The sour water from the separation section and the stripper section would be sent to the Sour Water Stripping Unit (SWSU) for removal of H2S and NH3 from it. Part of stripped water will be used as washed water in the DHPU and will be sent to Waste Water Treatment Plant (WWTP) which has been 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 DHPU is therefore not likely to further elevate the pollution levels at discharge point. The treated effluent of the BRPL refinery are stored in guard ponds. The guard ponds are provided temporary storage before being taken to tertiary treatment plant and make water reusable. The treated water from guard pond will discharged in to a small rivulet - the Tunia nala, originating from within the BRPL complex. The quality of water in the receiving stream at selected sites (Appendix VII) is being monitored by project authorities (Appendix VIII) and the physico chemical parameters are found to be well within the permissible limits of Indian Standards laid down by Central Pollution Control Board (CPCB). Additionally, the result of the water quality analysis conducted by Shriram Institute of Industrial Research and communicated to WII by EIL (Appendix IX, X & XI), also confirm that the physico chemical characteristic of water near the final discharge point are within the permissible limits of Indian standards specified by CPCB.

Disturbance from Associated Developments

The plot surrounding already has general infrastructure facilities such as railways siding for dispatch of products, approach road, and pipeline for disposal of effluents. other infrastructure support for project such as hydrogen source, tank farm, utility block, Control Room, Crude Distillation Unit (CDU) and Delayed Cocker Unit (DCU) already exists. General facilities such as warehouse laboratory, maintenance shops, safety and fire fighting unit and equipment also exist. 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. No significant stress id therefore foreseen from associated developments involving land-take and material management for infrastructure expansion.