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Environmental Investigation and Remediation of a Hazardous Waste Site

Part 4 - Results and Implications of Phase 1 Field Investigations

Samir G. Khoury, Ph.D., P.G.


Course Outline

This course, Part 4: Results and Implications of Phase 1 Field Investigations, briefly reviews the key points of the previous courses in the sequence (Parts 1 through 3), and presents the results of a new round of groundwater and soil sampling and analysis using the approach and testing procedures presented in Part 3 of this course series. This information is then compared to the earlier sampling and testing results obtained by the State Regulatory Agencies to allow evaluation of the validity of the earlier tests. Also presented is the initial characterization of the geologic and hydrologic settings of the site and the properties of its soils. Preliminary estimates of infiltration, down gradient groundwater travel time and an initial evaluation of environmental impacts are also included.

The results of this Phase of work allowed the development of a preliminary groundwater contour map and clearly indicated the presence of a plume of contamination moving downhill from the burial site. The report issued at the end of this phase of work was reviewed by several State Regulatory Agencies and a number of questions and concerns were raised. The questions and the Consultant’s responses, on behalf of the Institute, are included in the course as well as the press coverage received once the report was made public.

This course includes a multiple choice quiz at the end, which is designed to enhance the understanding of the course materials.

Learning Objective

At the end of Part 4, the student should understand the value of re-sampling the existing monitoring wells to compare the results with the earlier analyses performed by others. In this way, decisions made to perform additional field work will be made on a solid basis, thus maximizing the use of the previous and new information to plan the next phase of work.

In addition, the student will learn how the Consultant determined the:

The student will also learn:

Finally, the student will understand how the information thus generated was integrated and interpreted, and which recommendations were made. The regulatory review section will provide an insight into the mindset of the regulators and the press article reflects the general level of understanding of the public at large.

Intended Audience

This series of courses is intended for environmental engineers, environmental scientists, geotechnical engineers, civil engineers, engineering geologists, environmental geologists, hydrologists and other individuals who are interested to learn how environmental investigations are conducted.

Benefit to Attendees

Students who take this series of courses will learn how environmental problems are investigated; feasibility studies conducted and engineered remediation implemented. These steps are taken to prevent the spread and migration of contaminants to the accessible environment, thus protecting the health and safety of the population and stopping the otherwise inevitable and continual degradation of the environment.

Course Introduction

Starting in the 1960s a research institute (“Institute”) operated a small (0.65 acre) hazardous chemical and radioactive waste burial facility on its campus for about 20 years. All waste buried at the site resulted from the use of radioactive isotopes and chemicals in research experiments. Waste brought to the disposal site was in both solid and liquid form, and the liquids were in various types and sizes of containers. The waste was placed into narrow trenches dug into the soil at the burial site. The trenches were about 8 to 12 feet deep. Once waste reached about 4 feet from the surface, local dirt was used to fill the trench.

When the site was decommissioned and no longer used, it was fenced, posted and locked. Minimal ground maintenance was done until the State Radiation Protection Agency (State RPA) notified the Institute that they were to keep the fence clear of vegetation and the area within the fence mowed and free of trees. The following photo shows the waste disposal area after the site was decommissioned and the ground maintenance started:

Fig 1

Figure 1: Decommissioned waste disposal site at the Institute

Following decommissioning of the site, yearly testing of soil, surface water and vegetation by the State Radiation Protection Agency (State RPA) showed no evidence of significant radioactive contamination outside the burial area. In the late 1980s, the State RPA recommended that the Institute install a series of monitoring wells to allow sampling and testing of the groundwater. In response, and under the guidance of the State Groundwater Protection Agency (State GPA), the Institute installed five monitoring wells around the waste disposal site. The location of the five wells is shown on the following figure.

Fig 2

Figure 2: Location of Initial Monitoring Wells Installed around the Waste Disposal Site

About a month after installation, the State RPA collected groundwater samples from the five monitoring wells for radiological analysis. A year later, an additional groundwater sample was collected from Well No.3 for radiological and organic chemical analysis. The radiological analyses indicated that some of the groundwater samples in the immediate surroundings of the restricted area had elevated Tritium activities. It also appeared that organic chemical contamination might be present in the groundwater in the vicinity of the waste disposal area. Discovery of both chemical and radiological contamination outside the fenced burial area prompted the State RPA to require the Institute to design and implement an extensive investigation program. The Institute issued an RFP to environmental and engineering firms to retain the services of a technical services consultant (Consultant). The winning bidder reviewed existing information and developed an estimate of the inventory of the waste disposed of at the site and evaluated existing soil, vegetation, groundwater and surface water test results. The Consultant issued a Preliminary Site Condition Report summarizing the results of these initial studies. The State RPA and other State Regulatory Agencies then requested a characterization of the geology and hydrology of the area and the collection of additional soil, groundwater and surface water samples for analysis, including the installation of additional groundwater monitoring wells, in order to determine the size, extent, and characteristics of the down gradient contaminant plume.

Because the waste disposal site contained hazardous chemicals and radioactive isotopes, no additional field investigations could be started until a project-specific Health and Safety Plan was developed. A project-specific Quality Assurance Plan was also created, and the technical requirements were developed as part of the Sampling and Testing Plan. A set of Project Procedures was written to guide the field sampling and analysis programs that incorporated the requirements of each of the project plans. The relationship of the various plans, procedures and the field and laboratory activities is shown on the following flowchart.

Fig 3

Figure 3: Relationship of the Various Project Plans, Procedures and Field and Laboratory Activities

These aspects of the project are covered in the first three parts of this course series, as follows: Part 1 – Background and History Leading to Contract Award, Part 2 - Analysis of Existing Information and Regulatory Concerns, and Part 3 – Preparation of Project Plans and Procedures.

This course (Part 4) examines the Phase 1 field activities and conclusions drawn from the results of these studies. Following the consideration of a change implemented in the project reporting structure, the technical studies that are presented and discussed include:

The environmental impacts, conclusions and recommendations developed by the Consultant after this phase of work was completed are presented at the end of this course, as are questions from the regulatory agencies, the Consultant’s responses and media coverage following issuance of the updated site condition report.

Course Content

The course content is in the following PDF file:

Environmental Investigation and Remediation of a Hazardous Waste Site: Part 4 - Results and Implications of Phase 1 Field Investigations

Please click on the above underlined hypertext to view, download or print the document for your study. Because of the large file size, we recommend that you first save the file to your computer by right clicking the mouse and choosing "Save Target As ...", and then open the file in Adobe Acrobat Reader. If you still experience any difficulty in downloading or opening this file, you may need to close some applications or reboot your computer to free up some memory.

Course Summary

This course covered the results of the Phase 1 Field Investigations, where existing monitoring wells were re-sampled and analyzed for radionuclides and chemical contamination. The results were comparable to the results obtained by the State Radiation Protection Agency a number of years earlier, except that one compound (di-isopropyl ether) which was detected by the State RPA earlier, has not been detected during this phase of site work.

Four soil samples were also collected during the Phase 1 Field Investigations and tested for radionuclides and chemical compounds. None were detected.

Three rounds of water level measurements from the existing monitoring wells provided a first look at the depth and configuration of the groundwater beneath the waste disposal site. Based on published information the general site geology was evaluated. Two soil samples were collected for particle-size analysis, and preliminary infiltration rates and groundwater travel times were estimated.

The information obtained during this phase of work, combined with the review comments received from the State Regulatory Agencies were used to plan the Phase 2 field investigations, which consisted of installation of additional monitoring wells, sampling, analyzing and testing the new wells to determine the hydraulic properties of the soils. A detailed topographic survey of the entire site was implemented at the onset of the new phase of work to provide better control on well elevations and provide a base map for the evaluation of potential remedial options. This follow-up work is covered in Part 5 of this series of courses: Results and Implications of Phase 2 Investigations.

Quiz

Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.

Take a Quiz

DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.