Phase I consists of 51.6 acres of land, approximately 17% of the original 306 acres making up the Mound Plant. Phase I lies on the southern border of the plant and is made up of three distinct sections of the site property (see figure 1). There are ten existing buildings within Phase I and 25 former production-era buildings that have been since demolished. Phase I included 40 Potential Release Sites (PRS) all of which have been remediated and/or determined to require no further action. The area was once used by Mound for explosives testing, production related activities, administrative activities, utilities operations, waste processing operations, cleanup waste storage operations and other general plant uses.

The Record of Decision (ROD) for Phase I describes the selected remedy as institutional controls in the form of deed restrictions and monitored natural attenuation. The deed restrictions for Phase I are the same as the deed restrictions placed into the RODs for the four previously transferred parcels. The deed restrictions are as follows:

Maintenance of industrial/commercial land use;
Prohibition against residential use;
Prohibition against the use of ground water;
Site access for federal and state agencies for the purpose of sampling and monitoring;
Prohibition against the removal of Phase I soils from the DOE Mound property (as owned in 1998) boundary without the approval from Ohio Department of Health and Ohio Environmental Protection Agency.

Ground water monitoring wells 0411, 0443 and seep 0617 (see figure 2) exceed the Maximum Contamination Levels (MCL) for the chemical trichloroethene (five parts per billion (5 ppb)). Well 0411 has shown the highest trichloroethene (TCE) levels out of the three wells and seeps, ranging from 8 ppb to 16 ppb. The most recent result of 13 ppb was taken in January 2003. A soil sampling investigation was conducted to identify the potential source of the TCE. The results of the soil testing did not identify a source.

The soil and ground water data from the wells in the vicinity of well 0411 suggest that the TCE contamination is most likely limited to the area adjacent to well 0411. There is no known source of TCE in the soil in Phase I. The remedy selected for Phase I included monitored natural attenuation for this TCE exceedence. For specifics on the monitoring, consult the Phase I Record of Decision which can be found in the Miamisburg Closure Project CERCLA Public Reading Room located at the Miamisburg Senior Adult Center, 305 Central Avenue, Miamisburg, Ohio.