Geophysical Infrastructure Study: Jim Woodruff Lock and Dam

Science Center Objects

 A study site of the Geophysical Infrastructure Studies: Earthen Dams and Abandoned Mine Lands project.

Jim Woodruff Lock and Dam, Lake Seminole, Sneads, Florida

Jim Woodruff Lock and Dam is located on the Apalachicola River just south of the confluence of the Flint and Chattahoochee Rivers along the Georgia – Florida border. Construction was completed in 1954 and impounds Lake Seminole. The dam has a long history of excessive seepage along the right abutment and below the fixed crest spillway. Several karst features have been mapped over the years including sinkholes, both on land and along the lake bottom, and disappearing and reappearing streams. Such features were excavated and grouted during construction. Despite years of investigation of the dam foundation, there remains uncertainty on the flow paths of water below the fixed crest spillway and adjacent right abutment.   Seepage appearing in Polk Lake only accounts for about half of the water being discharged into the Apalachicola River at the “river boil”. The goal of this survey is to use complementary geophysical methods to determine if we can image karst features and potential groundwater pathways. 

The geophysical methods selected were electrical resistivity tomography (ERT), electromagnetic induction (EMI), self-potential (SP), and ground penetrating radar (GPR). The field campaign was completed in March 2018.

Jim Woodruff Lock and Dam Power House

The Jim Woodruff Lock and Dam power house, FL. View is to the east.

(Credit: Beth Burton, USGS. Public domain.)

geophysical equipment near dam spillway

Electrical resistivity tomography (ERT) equipment deployed parallel to the downstream toe of the Jim Woodruff fixed-crest spillway, FL. View is to the east.

(Credit: Beth Burton, USGS. Public domain.)

geophysical equipment near lake

Electrical resistivity tomography (ERT) equipment deployed along Lake Seminole, FL,  and across the fish deck area. View is to the northeast.

(Credit: Beth Burton, USGS. Public domain.)

geophysical equipment deployed near lake

Electrical resistivity tomography (ERT) equipment deployed along Lake Seminole, FL, and across the fish deck area. View is to the south.

(Credit: Beth Burton, USGS. Public domain.)

man gathering geophysical data near lake shore

Lew Hunter (USACE) acquiring electromagnetic induction (EMI) data on the right embankment along the western shore of Lake Seminole, FL. View is to the south.

(Credit: Beth Burton, USGS. Public domain.)

 

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