Sediment Sampling Surveys (cont.)
Borehole data used in this project are mainly associated with sediment retrieval or cuttings from boreholes drilled into substrata during the engineering phase of infrastructure development, such as the building or expansion of roads, bridges, dams, and buildings. A number of engineering factors are derived from the cuttings, including the strength and stability of the material underlying the infrastructure. Lithology and stratigraphy can also be determined from the cuttings. The advantage of borehole data is the extensive data set developed during the engineering process. Also, borehole depths tend to exceed depths obtained by most intrusive research methods. Interpretations of lithology and stratigraphy from borehole data can sometimes be subjective. This is because borehole data are derived from cuttings, and interpretations are normally done onsite and sometimes lack the rigorous attention of formal scientific scrutiny.
The borehole data used in this project were acquired by the Army Corps as a part of a large coastal data base of engineering borings throughout the area. In 1994 and 1995, the Waterways Experiment Station (U.S. Army Corps of Engineers) produced a series of technical reports (Dunbar and others, 1994; Dunbar and others, 1995) that include stratigraphic interpretations and correlation profiles based on the engineering logs of the cuttings. For the reports, the profiles were divided geographically into quadrangles. The quadrangles studied for this project were those surrounding the Lake Pontchartrain and Lake Borgne areas.