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HYDROSTRATIGRAPHY OF THE SAVANNAH RIVER SITE REGION
SRS region.
The strata that form the three aquifer systems consist of
fine to coarse grained sand, with local gravelly zones, deposited
under relatively high energy conditions in fluvial to shallow
marine environments. Marine limestone is locally
intercalated with the sands. Generally, the fine grained sediments
that comprise the regional confining systems were
deposited in low energy marine and fluvial environments.
Locally the confining system contain beds of sand or other
high permeability materials, but overall, the units retard vertical
flow between the overlying and underlying aquifer systems.
attains a thickness greater than 300 feet (Fig. 5), and consists
of sand and muddy sand of the Middendorf and lower part of
the Black Creek Formation (Fig. 2). The extent of the Midville
aquifer system is defined by the updip limit of the overlying
Allendale confining system (Fig. 3); northwest of the
updip terminus, the Midville aquifer is termed the McQueen
Branch aquifer of the Dublin-Midville and Floridan-Midville
aquifer systems (Figs. 1 and 2).
Figure 4. Isopach map of the Appleton confining system.
Figure 3. Map showing the updip limits of the confining systems
and extent of aquifer systems in the SRS region.
Appleton Confining System
Throughout the region, the Southeastern Coastal Plain
hydrogeologic province is separated from the Piedmont
hydrogeologic province by the Appleton confining system.
The Appleton rests directly on un-weathered crystalline and
sedimentary rocks of the Piedmont hydrogeologic province
(Fig. 1); it includes saprolite derived from weathering of
basement rocks, and muddy sand and sandy mud of the Cape
Fear Formation (Fig. 2). The Appleton confining system varies
from less than 50 to over 250 feet thick in the SRS region
(Fig. 4).
Midville Aquifer System
The Midville Aquifer system was defined by Clarke and
others (1985) in a well located near the town of Midville in
Burke County, Georgia. In the SRS region, the Midville
Allendale Confining System
The Allendale confining system consists of sandy mud
and clay of the Black Creek Formation and is defined in a
well drilled near the town of Allendale, Allendale County,
South Carolina. The Allendale is present in the southeastern
half of the SRS region and defines the regional extent of the
Midville and Dublin aquifer systems (Figs. 1 and 3). The
Allendale thins updip to become the McQueen Branch confining
unit of the Dublin Midville and Floridan Midville
aquifer systems (Fig.1).
Dublin Aquifer System
The Dublin aquifer system is present in the southeastern
half of the SRS region (Fig. 3), where it attains a thickness of
more than 300 feet (Fig. 6). North of the updip limit of the
Allendale confining system, the Dublin aquifer syste
becomes the Crouch Branch aquifer of the Dublin Midville
and Floridan Midville aquifer systems. The Dublin aquifer
system was defined by Clarke and others (1985) in a well
drilled near the town of Dublin in Laurens County, Georgia.
In the SRS region, the Dublin consists of sand and muddy
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