ABSTRACT
CONTENTS Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 517 Regulatory Concepts in Facility Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 519 Data Analysis Required for Monitoring System Design . . . . . . . . . . . . . . . . . . . . . . . . . 525
Selecting the Target Monitoring Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 526 Locating Background and Downgradient Wells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 528
Gradients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 528 Steep or Flat Gradients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 531
Procedures for Gradient Controlled Sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 534 Geologic Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 543
Single Homogeneous Aquifer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 545 Single Aquifer of Variable Hydraulic Conductivity . . . . . . . . . . . . . . . . . . . . . . . 546 Multiple Aquifers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 549 Low-Hydraulic Conductivity Environments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 551
Geologic Structural Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 554 Perched Ground Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 556 Secondary Hydraulic Conductivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 559 Density Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 563
Separation of Adjacent Monitoring Programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 566 Simple Gradient Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 566 Gradient and Lithology Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 567 Complex Ground-Water Flow Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 569
Monitoring System Design Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 571 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 571
At least three different types of ground-water monitoring programs are commonly applied to environmental site assessment and remediation projects. These include broadbased programs, such as reconnaissance monitoring of wide areas for the purpose of resource evaluation, and detection and assessment monitoring of ground-water quality beneath a specific facility, such as a solid-or hazardous-waste landfill or surface impoundment. Detection and assessment monitoring include program elements from the Resource Conservation and Recovery Act (RCRA) Subtitles C and D, and many aspects of
ground-water monitoring under the Superfund program. This chapter begins with a detailed discussion of detection monitoring programs, then addresses design aspects of assessment monitoring programs. Area-wide reconnaissance programs, which generally have very different design goals compared with the more regulation-driven detection and assessment programs, are not discussed in detail.
