Communications and Deliverables during Scoping

Purpose

For lead agency and contractor to identify actions that will abate immediate threat to public health or prevent further degradation of the environment; to obtain concurrence of support agency For lead agency and contractor to improve focus of RI and reduce time and cost; to obtain concurrence of support agency For lead agency and contractor to confirm need for FS; for lead agency and contractor to plan data collection; to obtain support agency review and concurrence For contractor to obtain lead agency review and approval; for lead agency to obtain support agency review and comment For contractor to obtain lead agency agreement that OSHA safety requirements are met For contractor to obtain lead agency review and approval; for lead agency to obtain support agency concurrence

Source: U.S. EPA, Guidance for Conducting Remedial Investigations and Feasibility Studies under CERCLA, EPA/540/

G-89/004, U.S. EPA, Washington, DC, October 1988. QA, quality assurance; RI, remedial investigation; FS, feasibility study; SAP, sampling and analysis plan; FSP, field sampling plan; QAPP, quality assurance project plan; OSHA, Occupational Safety and Health Administration.

Information Needed

Interim actions (if necessary)

Limited field investigations (if necessary)

Summary of existing data; field studies conducted prior to FS; identification of preliminary remedial action alternatives Documentation of QA and field sampling procedures

Documentation of health and safety procedures Documentation of all RI/FS tasks

Potential Methods of Information Exchange

Meeting Tech memo Other

Meeting Tech memo Other

Meeting Tech memo Other

Health and safety plan Work plan

2. Ensuring that access to the site and any other areas to be investigated has been obtained

3. Procuring equipment protective ensembles, air monitoring devices, sampling equipment, decontamination apparatus, and supplies (disposables, tape, notebook, and so on)

4. Coordinating with analytical laboratories, including sample scheduling, sample bottle acquisition reporting, chain-of-custody records, and procurement of close support laboratories or other in-field analytical capabilities

5. Procuring on-site facilities for office and laboratory space, decontamination equipment, and vehicle maintenance and repair, and sample storage, as well as on-site water, electric, telephone, and sanitary utilities

6. Providing for storage or disposal of contaminated materials (e.g., decontamination solutions, disposable equipment, drilling muds and cuttings, well-development fluids, well-purging water, and spill-contaminated materials)

7. Preparing field work, including time table, health, instrument, container, RCRA, equipment, and sample aspects

Site physical characteristics investigation

A site physical characteristics investigation examines the following12:

1. Surface features, including facility dimensions and locations, surface disposal areas, fencing, property lines and utility lines, roadways and railways, drainage ditches, leachate springs, surface water bodies, vegetation, topography, and residence and commercial buildings

2. Geology information, including the geology of unconsolidated overburden and soil deposits (thickness and areal extent of units, petrology, mineralogy, particle size and sorting, and porosity) and the geology of the bedrock (type of bedrock, petrology, structure and texture, discontinuities such as joints, fractures, and foliation, and unusual features such as dikes, lavas, and karsts)

3. Soils and vadose zone information, including soil characteristics (type, holding capacity, temperature, biological activity, and engineering properties), soil chemical characteristics (solubility, ion specification, adsorption, leachability, cation exchange capacity, mineral partition coefficient, and chemical and sorptive properties), and vadose zone characteristics (permeability, variability, porosity, moisture content, chemical characteristics, and extent of contamination)

4. Surface water information, including drainage patterns (overland flow, topography, channel flow pattern, tributary relationships, soil erosion, and sediment transport and deposition), surface water bodies (flow, stream widths and depths, channel elevations, flooding tendencies, and physical dimensions of surface water impoundments; structures; surface water/ groundwater relationships), and surface water quality (pH, temperature, total suspended solid, salinity, and specific contaminant concentrations)

5. Hydrogeology information, including geologic aspects (type of water-bearing unit or aquifer; thickness, areal extent of water-bearing units and aquifers; type of porosity; presence or absence of impermeable units or confining layers; depths to water table; thickness of vadose zone), hydraulic aspects (hydraulic properties of water-bearing unit or aquifer, such as hydraulic transmissivity, storativity, porosity, and dispersivity; pressure conditions such as confined, unconfined, or leaky confined), groundwater flow directions (hydraulic gradients horizontally and vertically, specific discharge, rate; recharge and discharge area; groundwater or surface water interactions; areas of groundwater discharge to surface water; seasonal variations of groundwater conditions), and groundwater use aspects (existing or potential aquifers; determination of existing near-site use of groundwater)

6. Atmospheric information, including local climate (precipitation, temperature, wind speed and direction, presence of inversion layers), weather extremes (storms, floods, winds), release characteristics (direction and speed of plume movement, rate, amount, and temperature of release, relative densities), and types of atmospheric hazards and hazards assessment

7. Human populations and land use

8. Ecological information, including information needed for public health evaluation (land use characteristics, water use characteristics) and information needed for environmental evaluation (ecosystem components and characteristics, critical habitats and biocontamination)

Contamination sources identification

The sources of contamination are usually those hazardous materials that are contained in drums, tanks, surface impoundments, waste piles, and landfills, as well as heavily contaminated media (such as soil) affected by the original leaking or spilling source. The purpose of defining sources of contamination is to help to identify the source location, potential releases, and engineering characteristics that are important in the evaluation of remedial actions, as well as waste characteristics, such as the type and quantity of contaminants that may be contained in or released to the environment, and the physical or chemical characteristics of the hazardous wastes present in the source.

Contamination determination

The targets for the determination of the nature and extent of contamination are groundwater, soil, surface water, sediments, and air.

16.5.1.2 Laboratory Analysis

Laboratory analysis provides data that will be used as the basis for decision-making. The data require that the analysis of samples in laboratories meets specific quality assurance and quality control (QA/QC) requirements.

16.5.1.3 Data Analysis

Data analysis should focus on the development or refinement of the conceptual site model by analyzing data on source characteristics, the nature and extent of contamination, the contaminants transport pathways and fate, and the effects on human health and the environment. All field activities, sample management and tracking, and document control and inventory should be well managed and documented to ensure their quality, validity, and consistency.

16.5.1.4 Community Relations Activities

Community relations should be properly maintained throughout the RI, including site characterization.

16.5.1.5 Reporting and Communication

During site characterization, communication is required between the lead and support agencies. The information is mainly on identifying ARARs, and includes a description of the contaminants of concern, the affected media, and any physical features. This information may be supplied by the preliminary site characterization summary or by a letter or other document.

A draft RI report should be produced for review by the support agency and submitted to the Agency for Toxic Substances and Disease Registry (ATSDR) for its use in preparing a health assessment and also to serve as documentation of data collection and analysis in support of the FS. The draft RI report can be prepared any time between the completion of the baseline risk assessment and the completion of the draft FS. Therefore, the draft RI report should not delay the initiation or execution of the FS.

16.5.2 Treatability Study

The objectives of the treatability study are primarily to achieve the following:

1. To provide sufficient data to allow treatment alternatives to be fully developed and evaluated during the detailed analyses, and to support the remedial design of a selected alternative

2. To reduce cost and performance uncertainties for treatment alternatives to acceptable levels so that a remedy can be selected

Figure 16.5 shows a decision process for treatability studies.12

Certain technologies have been sufficiently demonstrated so that the site-specific information collected during site characterization is adequate to evaluate and cost those technologies without conducting treatability testing.

A treatability study performed during an RI/FS is used to adequately evaluate a specific technology, including evaluating performance, determining process sizing, and estimating costs in sufficient detail to support the remedy selection processes. In general, treatability studies include the following steps:

1. Preparing a work plan (or modifying the existing work plan) for the bench or pilot studies

2. Performing field sampling, and/or bench testing, and/or pilot testing

FIGURE 16.5 Treatability investigations.

3. Evaluating data from field studies, and/or bench testing, and/or pilot testing

4. Preparing a brief report documenting the results of testing

A treatability study can be performed by using bench-scale or pilot-scale techniques. Bench study is usually performed in a laboratory, in which comparatively small volumes of waste are tested for the individual parameters of a treatment technology to determine effectiveness of the treatment alternative on the waste, differences in performance between competing manufacturers, differences in performance between alternative chemicals, sizing requirements for pilot-scale studies, feasible technologies to be pilot tested, sizing of those treatment units that would sufficiently affect the cost of implementing the technology, and compatibility of materials with the waste.

Pilot testing is intended to simulate the physical, biological, and chemical parameters of a full-scale process; therefore, the treatment unit size and the volume of waste to be processed in pilot systems greatly increase over those of bench-scale testing. As such, pilot tests are intended to bridge the gap between bench-level analyses and full-scale operation, and are intended to more accurately simulate the performance of a selected full-scale process.

Once a decision is made to perform treatability studies, the type of treatability testing (bench or pilot scale) should be decided. The choice of bench versus pilot testing is affected by the level of development of the technology. For a technology that is well developed and tested, bench studies are often sufficient to evaluate performance on new wastes. For innovative technologies, however, pilot tests may be required as information necessary to conduct full-scale test is either limited or nonexistent.

16.6 FEASIBILITY STUDY

The feasibility study (FS) utilizes the data on site characterization and remedial technology screening to establish remedial alternatives, in turn, to select the cost-effective remedial actions. The FS may be viewed as occurring in three phases:

1. The development of alternatives

2. The screening of alternatives

3. The detailed analysis of alternatives

In practice, the specific point at which the first phase ends and the second phase begins is not so distinct. Therefore, the development and screening of alternatives are discussed together to better reflect the interrelation of these efforts. Furthermore, in many instances, there is only a limited number of available options and it may not be necessary to screen alternatives prior to detailed analysis.

16.6.1 Development and Screening of Alternatives

The primary objective is to develop an appropriate range of waste management options to be analyzed more fully in the detailed analysis phase of the FS.12 Appropriate waste management ensures the protection of human health and the environment. It may involve, depending on site-specific circumstances, complete elimination or destruction of hazardous substances at the site, significant reduction of concentrations of hazardous substances to acceptable health-based levels, and prevention of exposure to hazardous substances via engineering or institutional controls, or some combination of the above.

Alternatives are typically developed concurrently with the RI site characterization, with the results of one influencing the other in a methodology of iteration. Alternatives for remediation are developed by assembling combinations of technologies, including the media to which they would be applied, into alternatives that address contamination on a site-wide basis or for an identified operable unit. The methodology of development and screening of alternatives consists of six general steps12:

1. Developing remedial action objectives specifying the contaminant and media of interest, exposure pathways, and preliminarily remediation goals that permit a range of treatment and containment alternatives to be developed on the basis of chemical-specific ARARs when available, other available information, and site-specific, risk-related factors

2. Developing general response actions for each medium of interest defining containment, treatment, excavation, pumping, or other actions, singly or in combination, that may be taken to satisfy the remedial action objectives for the site

3. Identifying volumes or areas of media to which general response actions might be applied, taking into account the requirements for protectiveness as identified in the remedial action objectives and the chemical and physical characterization of the site

4. Identifying and screening the technologies applicable for each general response action to eliminate those that cannot be implemented technically at the site and to specify remedial technology types

5. Identifying and evaluating technology process options to select a representative process for each technology type retained for consideration, alternative development and evaluation, with an intention to represent the broader range of process options within a general technology type

6. Assembling the selected representative technologies into alternatives representing a range of treatment and containment combinations, as appropriate

16.6.2 Detailed Analysis of Alternatives

Analysis and presentation of the relevant information are needed to allow decision-makers to select a site remedy.

16.6.2.1 Overview of Detailed Analysis of Alternatives

A detailed analysis of alternatives consists of the following:

1. Further definition of each alternative, if necessary, with respect to the volumes or areas of contaminated media to be addressed, the technologies to be used, and any performance requirements associated with those technologies

2. An assessment and a summary profile of each alternative against the evaluation criteria

3. A comparative analysis among the alternatives to assess the relative performance of each alternative with respect to each evaluation criterion

16.6.2.2 Criteria for Detailed Analysis of Alternatives

During the detailed analysis, each alternative is assessed against the evaluation criteria. The results provide decision-makers with sufficient information to adequately compare the alternatives, select an appropriate remedy for a site, and demonstrate satisfaction of the CERCLA remedy selection requirements in the record of decision:

1. Overall protection of human health and the environment. This is the overall aim of the process.

2. Compliance with ARARs. It is considered how each alternative will comply with ARARs, or if a waiver is required and how it is justified.

3. Long-term effectiveness. The long-term effectiveness of alternatives in maintaining protection of human health and the environment after response objectives have been met is investigated.

4. Reduction of toxicity, mobility, and volume through treatment. The anticipated performance of the specific treatment technologies an alternative may employ is evaluated.

5. Short-term effectiveness. This is an examination of the effectiveness of alternatives in protecting human health and the environment during the construction and implementation of a remedy until response objectives have been met.

6. Implementability. This is an evaluation of the technical and administrative feasibility of alternatives and the availability of the required goods and services.

7. Cost. Capital and operation and maintenance costs of each alternative are evaluated.

The overall criteria include cost-effectiveness, utilization of permanent solutions and alternative treatment technologies or resource recovery technologies to the maximum extent practicable, and satisfaction of the preference for treatment to reduce toxicity, mobility, or volume as a principal element, or the provision of an explanation if this preference is not met.12 This is needed in order to attain acceptance by the support agency and the community.

16.6.2.3 Factors Affecting Potentially Applicable Remedial Technologies

The following factors may affect the potentially applicable remedial technologies:

1. Site characteristics, which may limit or promote the use of certain remedial technologies

2. Waste characteristics, which may limit the effectiveness or feasibility of the remedial technologies: quantity/concentration, chemical composition, acute toxicity, persistence, biodegradability, radioactivity, ignitability, reactivity/corrosivity, infectiousness, solubility, volatility, density, partition coefficient, compatibility with chemicals, and treatability

3. Technology limitations, including level of technology development, performance record, inherent construction, operation, and maintenance problems

16.6.2.4 Procedure for Detailed Analysis of Alternatives

The procedure for a detailed analysis of alternatives can be generalized into the following steps14:

1. Data analyzing

2. Modeling, such as groundwater modeling

3. Defining the objectives of remedial actions

4. Identifying technologies

5. Posing alternatives—preliminary screening

6. Scrutinizing selected alternatives, including technical analysis, regulation compliance, public health and environmental analysis, and cost analysis

7. Recording the feasibility study

8. Selecting the remedial alternative

16.7 REMEDIAL TECHNOLOGIES

This section will cover site control for waste movement, site cleanup technologies, and point-of-entry protection. The main focus will be on site cleanup technologies including remediation for contaminated groundwater, soil, and sediments. The technologies involve in situ treatment, which converts contaminants to less hazardous materials, and ex situ methodologies, which use soil excavation or groundwater pumping to remove contaminants from the site, and then treat them.14-102

The techniques to remove the free product of nonaqueous phase liquids (NAPL) will not be included in this chapter, because NAPL is one of the main releases from leaking underground storage tanks and is covered in Chapter 18, "Remediation of Sites Contaminated by Underground Storage Tank Releases," which addresses remediation techniques for organic contaminants, especially volatile organic compounds (VOCs) in soil and groundwater.

16.7.1 Surface Site Control of Waste Movement

The purpose of site control is to achieve the following:

1. To prevent waste movement (in air, surface water, and groundwater)

2. To contain wastes in a limited area

3. To reduce and eliminate impact on the environment

4. To lower the overall remedial cost

Gas may be formed by microbiological degradation of organics, evaporation and volatilization of volatile materials, or chemical reactions. The high combustibility of methane—a major component of landfill-generated gas—is a potential hazard. The emission of gas can be accelerated by elevated temperatures and venting conditions. Air pollution, which may result from gaseous emissions and fugitive dusts, should be controlled at uncontrolled waste sites. The main tasks include control of air contamination associated with natural forces, control of air contamination associated with remedial actions, and monitoring air pollution.

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