Upon the approval of the Preliminary Plat application, assuming the public has not appealed the conditional approval, you may commence Final Engineering design. At this time your consultant engineer will revise or modify the preliminary plans to incorporate additional information or review comments from local agency staff. During this step, construction documents (drawings) will be completed and submitted to the reviewing agency. Although the local city or county government is the lead review agency, representatives from the local fire, sewer, water, and drainage districts need to be consulted to obtain their input on the added demand the plat has on their existing services. Some projects will need plans or documents reviewed by multiple agencies, for example by state or federal officials, in case the proposed plat is impacting shorelines or taking access from a state highway.

After a project's final engineering has been approved, it is time for construction. It is prudent for the applicant to secure several bids for the construction of the project from at least three reputable contractors with experience in the specific types of work needed for your project. After you have compared the bids and clarified any inconsistencies between them, you will award construction to the contractor that provides you with the greatest level of confidence that they can do a proper job within the stated budget. In order for the project to be accurately constructed, we advise a survey team be contracted to provide horizontal and vertical reference points on-site to guide the contractor. After construction, a survey crew will re-survey the parcel to verify that the roads and utilities have been constructed to plan and according to agency standards. This is known as an As-Built Survey.

Local governments usually require an applicant to post a bond before issuing a permit for the beginning of construction. These bonds provide the lead agency some assurance that, if something goes wrong, money will be available for the agency to correct any problems or complete the project itself. After a project has been successfully completed, bond for some period of time, usually about 2 years, are required to remain in effect to guarantee that the stormwater management facilities are functioning correctly, street trees are surviving, and all roadways and utilities are stable. During the latter phases of construction, the developer should begin preparation for submittal of the Final Plat documentation.