Standard Practice for Expedited Site Characterization of Vadose Zone and Groundwater Contamination at Hazardous Waste Contaminated Sites

Importancia y uso:

4.1 The ESC Process—This practice describes a process for characterizing hazardous waste contaminated sites8, that provides cost-effective, timely, high-quality information derived primarily from judgement-based sampling and measurements by an integrated, multidisciplinary project team during a limited number of field mobilizations. (See Appendix X1 for additional background on the ESC process, its distinction from traditional site characterization, and its relationship to other approaches to site characterization and Appendix X5 and X6 for illustrative examples of the ESC process.)

4.2 Determining Appropriateness of ESC—The ESC process should be initiated when an ESC client, regulatory authority, and stakeholders determine that contaminants at a site present a potential threat to human health or the environment and the ESC process will identify vadose zone, groundwater, and other contaminant migration pathways in a timely and cost-effective manner, especially when decisions concerning remedial or other action must be made as rapidly as possible. Situations where the process may be applicable are as follows:

4.2.1 ESA—Sites where environmental site assessments (ESAs) conducted by using Practice E1527, Practice E1528, and Guide E1903 identify levels of contamination requiring further, more intensive characterization of the geologic and hydrologic system of contaminant migration pathways. Section X1.5.3 discusses the relationship between ESAs and the ESC process.

4.2.2 Petroleum Release Sites—Large petroleum release sites, such as refineries. The user should review both this practice and Guide E1912 to evaluate whether the ESC or ASC process is more appropriate for such sites.

4.2.3 Subsurface Radioactivity—Sites or facilities with subsurface contamination by radioactivity.

4.2.4 Other Subsurface Contamination—Other sites or facilities where contaminant migration in the vadose zone and groundwater is a matter of concern and heterogeneity of the vadose zone and groundwater system or potential complex behavior of contaminants requires use of the ESC process.

4.3 Defining Objectives and Data Quality Requirements—The ESC process requires project objectives and data quality requirements that will provide the ESC client, regulatory authority, and stakeholders with the necessary information to analyze risk or apply regulatory standards-based cleanup in order to choose a course of action. Once these have been defined, the ESC process relies on the expert judgement of the core technical team, operating within the framework of an approved dynamic work plan, as the primary means for selecting the type and location of measurements and samples throughout the ESC process. An ESC project focuses on collecting only the information required to meet the project objectives and ceases characterization as soon as the objectives are met.

Note 4: This practice uses the term “data quality requirements” to refer to the level of data accuracy and precision needed to meet the intended use for the data. The U.S. EPA Data Quality Objectives (DQO) process is one way to accomplish this. The ESC process applies the concept of quality control and data quality requirements to geologic and hydrologic data as well as chemical data, but within a general framework of judgement-based rather than statistical sampling methods. Section X1.4.4 discusses the DQO process in more detail along with the role of judgement-based and statistically based sampling methods in the ESC process. Practice D5792 provides guidance on development of DQOs for generation of environmental data related to waste management.

4.4 Use of ESC Process for Risk Analysis and Remedial Action: 

4.4.1 Characterizing Contaminant Migration Pathways—Normally an ESC project will characterize the contaminant migration pathways (and sources if not already known) before any detailed risk analysis involving exposure to environmental receptors is performed, because environmental receptors are not known until the migration pathways are known. Risk analysis expertise will normally be required as an input into defining project objectives and data quality requirements (see 4.3); such expertise is involved as appropriate during field data collection phases of an ESC project. Identification of contaminant sources and environmental receptors for risk analysis is straightforward at most sites and does not, per se, require the ESC process. The ESC process focuses on characterizing vadose zone and groundwater contaminant migration pathways and determining the distribution, concentration, and fate of contaminants along these migration pathways, because these factors are more difficult to identify than sources and environmental receptors.

4.4.2 Considering Remedial Action and Alternatives—The ESC process is designed to avoid a presumption that remedial action is required (that is, an engineered solution rather than no further action or ongoing monitoring). In any ESC project, remediation engineering expertise is incorporated into the process at the earliest point at which a need for remedial action is identified. (See 13.3.) Guide D5745 provides guidance for developing and implementing short-term measures or early actions for site remediation.

4.5 Flexibility Within ESC—Modification of procedures described in this practice may be appropriate if required to satisfy project objectives or regulatory requirements, or for other reasons. The ESC process is flexible enough to accommodate a variety of different technical approaches to obtaining environmental data. However, for an investigation to qualify as an ESC project, as formalized by ASTM, modifications should not eliminate any of the essential features of the ESC process listed in Table 1. Alternative site characterization approaches that use some, but not all, of the essential elements described in Table 1 may be appropriate for a site, but these approaches would not qualify as an ESC project as defined in this practice.

Note 5: Users may prefer to use or develop alternative terminology for different aspects of the ESC process, depending on the regulatory context in which it is applied. However, precise or approximate equivalencies to steps or functions in the ESC process should be clearly identified.

4.6 Use of ESC in Conjunction with Other Methods—This practice can be used in conjunction with Guide D5730 for identification of potentially applicable ASTM standards and major non-ASTM guidance. In karst and fractured rock hydrogeologic settings, this practice can be used in conjunction with Guide D5717.

Subcomité:

D18.01

Referida por:

D5745-23, D6432-19, D6820-20, E2081-22, D6067_D6067M-17, D6001_D6001M-20, E2616-09R20, D6431-18, D6639-18, E2531-06R20, D6430-18, D6429-23, E1689-20, E3358-23A, D5777-18, D7128-18

Volúmen:

04.09

Número ICS:

13.030.99 (Other standards related to wastes)

Palabras clave:

environmental site characterization; exploration; feasibility studies; field investigations; geological investigations; geophysical investigations; groundwater; hydrologic investigations; maps; preliminary investigations; reconnaissance surveys; sampling; site characterization; site investigations; subsurface investigations;