To file invoices for all DEP contracts, vendors must use the DEP Invoice Platform. Vendors will need to create an account upon initially accessing the platform.Bystep guide to understanding the bidding process, along with tips on submitting a successful bid. One-on-One Assistance. State agencies are required to submit the complete procurement record and all documentation necessary for OSC to complete its review. Gov with the RFB's number and title in the subject line of your e-mail. Sign the bid form manually in ink. Sealed bidding is a method of contracting that employs competitive bids, public opening of bids, and awards. (1) The Advertisement and Proposal for Bids. Learn how to write a winning bid proposal for construction projects.