Accession Number:

AD1147197

Title:

Geophysical Investigation to Assess Condition of Grouted Scour Hole: Old River Control Complex-Low Sill Concordia Parish, Louisiana

Descriptive Note:

[Technical Report, Interim Report]

Corporate Author:

ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MSOAK RIDGE INST FOR SCIENCE AND EDUCATION TN

Report Date:

2021-09-09

Pagination or Media Count:

44

Abstract:

Geophysical surveys, both land-based and water-borne, were conducted at the Old River Control ComplexLow Sill, Concordia Parish, LA. The purpose of the surveys was to assess the condition of the grout within the scour region resulting from the 1973 flood event, including identification of potential voids within the grout. Information from the ground studies will also be used for calibration of subsequent marine geophysical data and used in stability analysis studies. The water-borne survey consisted of towed low frequency 16-80 MHz ground penetrating radar GPR, whereas the land-based surveys used electrical resistivity and seismic refraction. The GPR survey was conducted in the Old River Channel on the upstream side of the Low Sill structure. The high electrical conductivity of the water 50 mSm precluded penetration of the GPR signal thus, no useful data were obtained. The land-based surveys were performed on both northeast and southeast sides of the Low Sill structure. Both resistivity and seismic surveys identify a layered subsurface stratigraphy that corresponds, in general, with available borehole data and constructed geologic profiles. In addition, an anomalous area on the southeast side was identified that warrants future investigation and monitoring.

Descriptors:

Subject Categories:

  • Geology, Geochemistry and Mineralogy
  • Active and Passive Radar Detection and Equipment
  • Civil Engineering

Distribution Statement:

[A, Approved For Public Release]