Works contract

One of my client is PWD contractor, making roads, dam, bridge for government department. All the Bills of Government contractor are finalized & made by PWD dept. (only estimates are provided by contractor).After GST, PWD dept. is not mention regarding gst in bills of contracts or price schedule. Therefore, there is no tax charged by contractor towards the supply amount. Only Tender value is received by contractor. Now, I have following queries towards GST - ‎ 1.Whether GST is payable by contractor or PWD because contractor neither seperatly received GST amount nor it is mentioned in contract and if payable by contractor then tender value is treated as taxable value or total value including GST 2. What are the provisions for Government contractors (PWD Contractors) under GST ?