Do not use a unilateral CO for work that is outside the scope of the project. Work that is outside the limits (except when addressing transition areas) or that is outside the original intent of the project should not be forced on a contractor through the use of a unilateral CO. Notify CST of any unilateral CO’s. These types of CO’s do not require CST review or concurrence. The DE will approve and sign all unilateral COs.