In the video below, Dan Biersdorf, discusses partial takings in eminent domain
An eminent domain partial taking occurs when the government acquires a portion of the property, not the entire parcel. The value of the land and any improvements to the land which are actually taken in an eminent domain proceeding are known as the direct damages, and the value of the remainder parcel is known as the severance damages. Numerous legal rules and valuation concepts exist in eminent domain partial takings.
Partial Taking by Specific Issue
Questions arise when the condemning authority acquires less than all of the property. In this instance, just compensation is determined by valuing all of the owner’s property before the taking (larger parcel) and subtracting the value of the property that the owner has left after the taking (remainder).
In determining the larger parcel in an eminent domain partial taking, there is a concept known as the three unities. The three unities relate to the unity of ownership, unity of use, and the unity of contiguity.