Release Block D has two buildings. Formerly know as Building 105, and located at the northern edge of Release Block D, this building was built in 1990 and was used as a machine shop. The building is now leased to Thaler Machine Company. Building 100, located at the southern edge of Release Block D is presently unoccupied. This building was once used as a post for the plant's security force.

Sixteen Potential Release Sites (PRS) were identified within Release Block D. Thorium contamination was removed from the PRS 304 area in October and November 1998. All other PRS' were deemed to require no further action.

The Record of Decision for Release Block D indicates that the remedy for this portion of land is institutional controls in the form of deed restrictions on the land use. The following property restrictions have been agreed upon and will be imposed to maintain protection of human health and the environment:

Industrial use must be maintained,
The use of bedrock ground water is prohibited,
Site access for federal and state agencies for the purpose of sampling and monitoring must be provided, and
Soils from Release Block D will not be removed from the Mound National Priority List (NPL) Facility boundary without the approval from the Ohio Department of Health.

As with all land that is transferred from the Mound Plant, Release Block D is inspected annually to assess the effectiveness of the institutional controls. The results of the annual inspection are documented in the Annual Assessment of the Effectiveness of Institutional Controls applied to the former Mound Site Property.