1. Scientist, National Envionment Engineering Research Institute, Nagpur-440 020, India (corresponding author). E-mail: nemap49@rediffmail.com
2. Scientist, National Environmental Engineering Research Institute, Nagpur-440 020, India.
3. Associate Professor, Dept. of Civil Engineering, IIT, Roorkee-247 667, India.
4. Professor, Dept. of Civil Engineering, IIT, Roorkee-247 667, India.
5. Ex-Director, National Environmental Engineering Research Institute, Nagpur-440 020, India.