When conducting environmental and engineering investigations in karst terranes, engineers and geologists often supplement exploratory borehole results with data gathered from surface geophysics to reduce the site-characterization cost and establish the most useful locations for borings or samples. When conducting resistivity investigations, a frequently occurring problem is the need to determine which of the many existing electrode configurations will respond best to the material changes in karst features. Each array has its advantages and disadvantages in terms of depth of investigation, sensitivity to horizontal or vertical variations, and signal strength. In the application presented in this paper, numerical forward modeling was conducted of dipole-dipole, Schlumberger, and Wenner arrays, and they produced markedly different anomaly shapes for a conceptual model of the development of a cover-collapse sinkhole. The resolution of the three above-mentioned arrays was further evaluated along a section of I-70 near Frederick, Maryland, where a sinkhole had occurred in the median of the highway. The image from the dipole-dipole array appeared to be better than those from the Wenner and Schlumerger arrays in displaying the sinkhole collapse area. However, they are all less effective than a mixed array, in which apparent resistivities from all the three arrays are combined and processed together in the model. Because the mixed array requires a significant increase in data collection, the dipole-dipole array appears to be the most effective and less costly configuration in mapping karst hazards areas. This conclusion was then confirmed by two case studies.

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Currently, a window of opportunity exists to greatly expand career counseling services for kindergarten through twelfth grade students. Enhanced career development activities for all students are presently mandated by federal legislation (School-to-Work Opportunities Act of 1994), supported by widespread public opinion (Brown, Minor, & Jepsen, 1992), and advocated by the school counselor profession (American School Counseling Association, 1985). Unfortunately, as Bloch (1996) pointed out, in many states school administrators and counselors have limited awareness of and commitment to workforce preparation policies (Secretary's Commission on Achieving Necessary Skills, 1991) and related K-12 career development objectives (National Occupational Information Coordinating Committee, 1989) (NOICC). However, Lapan, Gysbers, and Sun (1997) found in a statewide study of high schools where counselors were more fully implementing a comprehensive guidance program concept (Gysbers & Henderson, 1994) students reported that: more career information was being made available to them, that their education was better preparing them for their futures, and that they were earning higher grades.Recently, increased attention has focused on the specific career development needs of middle school students (e.g., Lapan & Jingeleski,

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