ABSTRACT
Well-planned field investigations for assessing soil and ground-water quality or contamination reduce costs and yield better results than investigations that are conducted using a cookbook or haphazard approach. This chapter focuses on the things that should be done before initiating a significant level of fieldwork and reviews some statistical concepts and techniques that are especially important in contaminant investigations. Subsequent chapters cover more specific field methods for local and site investigations:
5.1 OVERVIEW OF INVESTIGATION PLANNING PROCESS
5.1.1 Investigation Objectives
A clear definition of objectives is the first step in effective planning. The objectives of an investigation will in large measure define the approach and methods that will be used. Some common objectives include:
A clear statement and understanding of an investigation program’s objectives must precede decisions concerning sampling locations, piezometer or well types, numbers, location, depth, constituents of interest, and methods of sample collection, storage, transport, and analysis. Each decision requires consideration of the data needs and associated costs involved in each phase of a site characterization and monitoring program. In general, a phased approach is best, in which experimental design focuses on the reasoning behind each piece of data that is collected, and use of less expensive field methods guides use of more expensive methods as needed. For example, surface geophysical methods and handheld or truck-mounted subsurface probing devices can guide the location of boreholes and the monitoring of well installations using larger drill rigs. In the same way, use of less expensive chemical field screening and analytical techniques on a relatively large number of samples can guide selection of a fewer number of samples for chemical analysis in fixed laboratories (Section 9.6).
