Be careful with this one because there are different options that the existing shareholders could elect. In the SEC filing on 8/1/17, please see Article 2 - "Conversion of Securities in the Merger" that contains details of these transactions, the options available to shareholders, fractional shares and more.
Same info is found in this document that Catherine found, please see page 3 at "Part II, 14" : https://s1.q4cdn.com/838591571/files/doc_downloads/governance/2018/US-Tax-Information-On-CH2M-Acquisition-Form-8937.pdf
More info for investors is here from the company website post-merger, updated in Feb 2018 with additional info in Q & A format. Section 5 - Tax Reporting starts on page 8 that should help you most, including where to find stock FMV price and the link to computershare for cost basis info: http://s1.q4cdn.com/838591571/files/doc_downloads/CH2M/FAQ/ch2m-jacobs-post-closing-frequently-asked-questions-020818.pdf