Land development can also be done in conjunction with the construction of Single Family homes. If we are only going to speak of Land Development of 5 or more units then the following forms are required for a preliminary site/subdivision plan: A Preliminary Residential Site Subdivision Plan is needed for all new subdivisions. Preliminary residential sites and subdivision plans are meant to show the layout of the site including the necessary public improvements, utilities, structures; feasibility of water supply and sewage disposal; the relationship of the site to other vacant land or developments.