Hiring of Services for Engineering,Procurement,Construction & Commissioning (EPC) of a Group Gathering Station (GGS) Consisting of an OCS,ETP plus STP and WIS at Lakwagaon in Sivasagar District,Assam on LSTK Basis followed by Comprehensive Operation & Maintenance (O&M) Services of the GGS for 02 Years with a Provision for Extension of the O&M Service by another 01 Year