In an RFI, the focus is on identifying and describing releases: what contaminants were released, in what amounts, where they are located, and how far and in what media they have spread. This information provides the basis for risk assessment and planning follow-up actions. Temperature is not the primary factor in defining releases, paint color has no bearing on contamination, and site history is relevant to understanding potential releases rather than being irrelevant.

Pathways describe how contaminants move through the environment from a source to receptors, by traveling in environmental media. The major transport media are water and air. Contaminants can move with surface water in rivers, lakes, and streams, and they can also move with groundwater through aquifers, delivering contaminants to water supplies and ecosystems. The atmosphere carries contaminants as airborne particles or gases, allowing them to disperse over distances and eventually deposit elsewhere. This is why surface water, groundwater, and wind capture the key transport routes. Ingestion and inhalation are exposure routes—ways people or organisms come into contact with contaminants after they’ve moved through the environment—not the transport media themselves. Focusing only on airflow omits important waterborne pathways, and mentioning only groundwater and soil moisture leaves out surface water and the role of the atmosphere.

Groundwater flow follows the hydraulic gradient, moving from higher hydraulic head to lower hydraulic head. To determine flow direction at a site, measure hydraulic heads at multiple wells across the area, ideally during the same groundwater conditions. Use those head values to compute the gradient between locations and plot head contours (equipotential lines) on a map. The flow direction is perpendicular to these contours, from high head toward low head, which aligns with Darcy’s law that relates flow to the gradient. Rainfall intensity tells you about recharge, not the current direction of groundwater movement. Soil color doesn’t indicate the subsurface hydraulic gradient, and surface temperature reflects near-surface conditions rather than subsurface flow.

Quality assurance and quality control should be implemented throughout all phases of planning, execution, and evaluation. In planning, QA/QC establishes the standards, protocols, acceptance criteria, and documentation practices that guide every activity. In execution, it translates into calibration of instruments, use of field blanks and duplicates, adherence to procedures, and ongoing data checks to catch problems early. In evaluation, QA/QC verifies data integrity, assesses whether results meet quality criteria, records deviations, and drives corrective actions before reporting. This continuous application ensures data are reliable and comparable across the project, rather than being trustworthy only at the start or neglected during later stages.