Environmental Restoration: Part 5 - Phase 2 Field Investigations

In Environmental Restoration: Part 5 - Phase 2 Field Investigations, you'll learn ...

• Understand how and why the initial field investigation conducted around the waste disposal site during Phase 1 (Course Part 4) was extended in both the up-gradient and down-gradient directions
• How subsurface geologic and hydrologic information is obtained
• How permeability measurements are performed in the field
• Preparation of an accurate topographic map

Overview

Credit: 3 PDH

Length: 50 pages

This course, Part 5, is the fifth in a series of six sequential courses, Parts 1 through 6, that present the history and steps taken to remediate the environmental hazards created by the land disposal of chemical and radioactive wastes on the campus of a research institute. The practice of shallow land burial of hazardous wastes was widely used throughout the US between the 1960s and the 1980s. However, since the late 1980s both federal and state legislations were promulgated requiring the environmental regulatory agencies throughout the US to investigate operating, decommissioned and abandoned landfills of all types having in mind the ultimate goal of mitigating the impacts these waste disposal sites have on the natural environment. This series of courses, are written from the perspective of a Manager who leads a team charged with the implementation of an environmental Remedial Investigation (RI), Feasibility Study (FS) and Engineered Remediation (ER) of a hazardous waste disposal site. The courses draw from numerous environmental investigations managed by the author across the US. As such, the scenarios that are presented are similar to those a professional environmental engineering practitioner faces in real life.

The case that is developed here is used as an example and a vehicle to present and discuss concepts and project implementation strategies gained through years of experience. This information is not usually found or taught in traditional or standard academic courses dealing with environmental issues or investigations. In their entity this series of courses can be considered an implementation guide for conducting environmental investigations at hazardous waste disposal sites. The environmental problems in the example scenario are those encountered at a decommissioned hazardous and low-level radioactive waste disposal site owned by a research institute. The presentations are sequenced in the order in which investigations would be conducted by an environmental consulting firm contracted to perform and supervise the work that would be done in order to assess the magnitude of the problem and develop appropriate mitigation strategies for the rehabilitation of the site.

This course, Part 5: Phase 2 Field Investigations, briefly reviews the key points of the previous courses in the sequence (Parts 1 through 4), and presents the results of the Phase 2 field investigations. This phase of work started with the preparation of an accurate topographic base map of the waste disposal site and its vicinity on which all data collected in the field were plotted for analysis and interpretation. Three additional monitoring wells were installed around the waste disposal site to collect geologic, hydrologic and chemical data. Permeability measurements were performed in these wells and groundwater samples from most of the wells were analyzed to detect any contaminants that may be present.

A down gradient groundwater investigation was initiated with the installation of two monitoring wells at the base of the slope west of the waste disposal site. One of the wells was screened in the soil that overlies the bedrock, while the other was screened in the bedrock. Contaminants were detected in the well with its screen in the soil above the bedrock, while no contamination was detected in the well with its screen in the bedrock. The investigation was then extended into the floodplain of the Creek.

The floodplain was investigated by the Hydropunch™ technique. This technique provided a fast and relatively inexpensive method to collect a large amount of information to determine the presence or absence of groundwater contaminants within the floodplain.