Standard Active Last Updated: Jan 08, 2020
ASTM E1903-19

Standard Practice for Environmental Site Assessments: Phase II Environmental Site Assessment Process

Significance and Use

4.1 Uses: 

4.1.1 This practice is intended for use on a voluntary basis by parties who wish to evaluate known releases or likely release areas identified by the user or Phase II Assessor, and/or to assess the presence or likely presence of substances, for legal or business reasons such as those described in 1.2.

4.1.2 This practice is intended to meet the business community's need for a written, practical reference describing a scientifically sound approach to investigating a property to evaluate the presence or likely presence of a substance. It is impossible to generalize about the contexts in which a user may wish to conduct such investigations or the degree of confidence a user may require in the results. In any context, this practice, being rooted in sound scientific methodology, can assist users in achieving an objective and defensible assessment. This practice does not address the evaluation of business environmental risks in light of data collected through the Phase II ESA process. Such evaluation is a function of site- and transaction-specific variables, and of the user’s objectives and risk tolerance. This practice contemplates that the Phase II ESA process will be planned and conducted with such variables in mind, and that the user will evaluate legal, business and environmental risks in light of known data relating to the particular site and transaction, and in consultation with legal and business advisors as well as the Phase II Assessor. Likewise, this practice does not define the threshold levels at which target analytes pose a concern of significance to the user. Users may apply this practice not only in light of applicable regulatory criteria and relevant liability principles, but also to meet self-defined objectives. If a Phase II ESA conducted in accordance with this practice provides sufficient information from which the Phase II Assessor can conclude, consistent with the scientific method, that the question to be addressed by the assessment (see 6.4.1) has been answered, then further assessment is not warranted to meet the objectives of the assessment.

4.1.3 Use Not Limited to CERCLA—This practice is designed to assist a user in developing information about the environmental condition of the property and has utility for a wide range of target analytes (e.g., including diffuse anthropogenic contamination and naturally occurring substances) and users including those who may have no actual or potential CERCLA concerns.

4.1.4 Site- and Transaction-Specific—The scope of a Phase II ESA is site-specific and context-specific. The assessment process defined by this practice is intended to generate sound, objective, and defensible information sufficient to satisfy diverse user objectives.

4.1.5 Use by Other Parties—This practice does not define whether or to what extent any person other than the user may use or rely upon a Phase II ESA prepared for the user. The appropriateness of third party use or reliance is a contractual matter that should be addressed between user and Phase II Assessor, see Appendix X2, section X2.4.

4.2 Principles—The following principles are an integral part of this practice and are intended to be referred to in resolving any ambiguity or exercising such discretion as is accorded the user or Phase II Assessor.

4.2.1 Elimination of Uncertainty—No Phase II ESA can eliminate all uncertainty. Furthermore, any sample, either surface or subsurface, taken for chemical testing may or may not be representative of a larger population. Professional judgment and interpretation are inherent in the process, and even when exercised in accordance with objective scientific principles, uncertainty is inevitable. Additional assessment beyond that which was reasonably undertaken may reduce the uncertainty. Failure to Detect—Even when Phase II ESA work is executed competently and in accordance with this practice, it must be recognized that certain conditions present especially difficult target analyte detection problems. Such conditions may include, but are not limited to, complex geological settings, unusual or generally poorly understood behavior and fate characteristics of certain substances, complex, discontinuous, random, dynamic, or spotty distributions of existing target analytes, physical impediments to investigation imposed by the location of utilities and other man-made objects, and the inherent limitations of assessment technologies. Limitations of Information—The effectiveness of a Phase II ESA may be compromised by limitations or defects in the information used to define the objectives and scope of the investigation, including inability to obtain information concerning historical site uses or prior site assessment activities despite the efforts of the user and Phase II Assessor to obtain such information in accordance with 5.1.3. Chemical Analysis Error—Chemical testing methods have inherent uncertainties and limitations. The Phase II Assessor shall build quality control and quality assurance measures into the assessment, as outlined in Section 7. The Phase II Assessor should require the laboratory to report any potential or actual problems experienced, or nonroutine events which may have occurred during the testing, so that such problems can be considered in evaluating the data. The Phase II Assessor should subsequently identify such problems in any reports or documentation provided to the user. Any laboratory utilized for chemical testing shall be accredited in accordance with applicable state requirements.

4.2.2 Level of Assessment—Phase II ESAs do not generally require an exhaustive assessment of environmental conditions on a property. There is a point at which the cost of information obtained and the time required to obtain it outweigh the benefit of the information and, in the context of private transactions and contractual responsibilities, may become a material detriment to the orderly conduct of business. If the presence of target analytes is confirmed on a property, the extent of further assessment is a function of the degree of confidence required and the degree of uncertainty acceptable, in relation to the objectives of the assessment.

4.2.3 Comparison With Subsequent Inquiry—The justification and adequacy of the findings of a Phase II ESA in light of the findings of a subsequent inquiry should be evaluated based on the reasonableness of judgments made at the time and under the circumstances in which they were made.

4.2.4 Data Usability—Investigation data generally only represent the site conditions at the time the data were generated and site conditions can be dynamic. Therefore, the usability of data collected as part of a Phase II ESA may have a finite lifetime depending on the application and use being made of the data. To the extent that investigation data would fall within the scope of data used in a Phase I ESA conducted pursuant to Practice E1527 or Practice E2247, the lifetime limits defined by those standards apply. In all other respects, a Phase II Assessor should evaluate whether previously generated data are appropriate for any subsequent use beyond the original purpose for which they were collected, or are otherwise subject to lifetime limits imposed by other laws, regulations or regulatory policies.

4.2.5 Phase II Assessor Does Not Provide Legal or Business Advice—The Phase II ESA is intended to develop and present sound, scientifically valid data concerning actual site conditions. It shall not be the role of the Phase II Assessor to provide legal or business advice.


1.1 This practice2 covers a process for conducting a Phase II environmental site assessment (ESA) of a parcel of property with respect to the presence or the likely presence of substances including but not limited to those within the scope of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) (e.g., hazardous substances), pollutants, contaminants, petroleum and petroleum products, and controlled substances and constituents thereof. It specifies procedures based on the scientific method to characterize property conditions in an objective, representative, reproducible, and defensible manner. To promote clarity in defining Phase II ESA objectives and transparency in communicating and interpreting Phase II ESA results, this practice specifies adherence to requirements for documenting the scope of assessment and constraints on the conduct of the assessment process.

1.1.1 A user's interest in the presence or likely presence of substances in environmental media at a property may arise in a wide variety of legal, regulatory, and commercial contexts, and may involve diverse objectives including those listed in 1.2. This practice contemplates that the user and the Phase II Assessor will consult to define the scope and objectives of investigation in light of relevant factors, including without limitation the substances released or possibly released at the property, the nature of the concerns presented by their presence or likely presence, the behavior , fate and transport characteristics of substances released or possibly released, the portion of the property to be investigated, the information already available, the degree of confidence needed or desired in the results, the degree of investigatory sampling and chemical testing needed to achieve such confidence, and any applicable time and resource constraints. This practice requires that Phase II activities be conducted so that the resulting scope of work is performed, and the stated objectives are achieved, in a scientifically sound manner.

1.1.2 A Phase II ESA in accordance with this practice may be conducted after site assessment activities in accordance with Practice E1527 for Phase I Environmental Site Assessments: Phase I Environmental Site Assessment Process, Practice E2247 for Environmental Site Assessments: Phase I Environmental Site Assessment for Forestland or Rural Property, EPA’s All Appropriate Inquiries (AAI) Rule, 40 C.F.R. Part 312, or Practice E1528 for Limited Environmental Due Diligence: Transaction Screen Process. In defining the scope and purposes of a Phase II ESA, however, previous decisions to classify property conditions or areas as RECs, or to refrain from doing so, are not determinative as to whether investigation of the same conditions or areas is appropriate to meet the objectives of the Phase II ESA.

1.2 Objectives—This practice is intended for use where a user desires to obtain sound, scientifically valid data concerning actual property conditions, whether or not such data relate to property conditions previously identified as RECs or data gaps in Phase I ESAs. Without attempting to define all such situations, this practice contemplates that users may seek such data to inform their evaluations, conclusions, and choices of action in connection with objectives that may include, without limitation, one or more of the following:

1.2.1 Objective 1—Assess whether there has been a release of hazardous substances within the meaning of CERCLA, for purposes including landowner liability protections (i.e., innocent landowner, bona fide prospective purchaser, and contiguous property owner).

1.2.2 Objective 2—Provide information relevant to identifying, defining or implementing landowner “continuing obligations,” or the criteria established under CERCLA (e.g., exercising appropriate care by taking reasonable steps to prevent or limit exposures to previously released hazardous substances) for maintaining the CERCLA landowner liability protections.

1.2.3 Objective 3—Develop threshold knowledge of the presence of substances on properties within the scope of the CERCLA definition of a “brownfield site” and as required for qualifying for brownfields remediation grants from the EPA Brownfields Program.

1.2.4 Objective 4—Provide information relevant to identifying, defining and evaluating property conditions associated with target analytes that may pose risk to human health or the environment, or risk of bodily injury to persons on the property and thereby give rise to potential liability in tort.

1.2.5 Objective 5—Provide information relevant to evaluating and allocating business environmental risk in transactional and contractual contexts, including transferring, financing and insuring properties, and due diligence relating thereto.

1.2.6 Objective 6—Provide information to support disclosure of liabilities and contingent liabilities in financial statements and securities reporting.

1.2.7 Additional information concerning these six objectives may be found in the Legal Appendix, Appendix X1.

1.3 Scope of Assessment in Relation to Objectives—The scope of a Phase II ESA is related to the objectives of the investigation. Both scope and objectives may require ongoing evaluation and refinement as the assessment progresses.

1.3.1 In developing the scope of work and in evaluating data and information concerning the property, the Phase II Assessor must determine whether the available information is sufficient to meet the objectives of the investigation. Even after conducting Phase II activities to generate additional data, the Phase II Assessor must independently evaluate the sufficiency of the data in relation to the objectives. As the investigation progresses, the objectives may be refined or redefined in consultation between the user and the Phase II Assessor.

1.3.2 A single round of sampling and chemical testing may not always provide data sufficient to meet the chosen objectives. If not, this practice contemplates additional sampling in an iterative sequence that concludes when the available data are sufficient. This practice also acknowledges, however, that the user may instead elect either to redefine the objectives so that they can be met with the data available, or to terminate the investigative process without meeting the stated objectives. The Phase II Assessment report must disclose any respect in which available data are insufficient to meet objectives.

1.3.3 This practice does not require full site characterization in every instance, but may be used to carry out an investigation sufficient for that purpose if desired to meet the user's objectives.

1.4 Needs of the User—The user and Phase II Assessor must have a mutual understanding of the context in which the Phase II ESA is to be performed and the objectives to be met by the investigation, i.e. the specific questions to be answered or problems to be resolved by the Phase II ESA. The scope of Phase II activities must be defined in relation to those objectives.

1.4.1 The degree of confidence desired by the user influences the scope of the investigation and the evaluation of data. More extensive testing and more iterations of sampling and analysis may be needed if the objectives require detailed conclusions with high confidence. Less testing and fewer iterations of sampling and analysis may be needed if the objectives of the assessment require only general conclusions.

1.5 Limitations—This practice is not intended to supersede applicable requirements imposed by regulatory authorities. This practice does not attempt to define a legal standard of care either for the performance of professional services with respect to matters within its scope, or for the performance of any individual Phase II ESA.

1.6 Organization of This Practice—This practice has nine sections and four appendices. Section 1 covers the Scope of the practice. Section 2, Referenced Documents, lists ASTM and other organizations’ related standards and guidance that may be useful in conducting Phase II ESAs in accordance with this practice. Section 3, Terminology, contains definitions of terms and acronyms used in this practice. Section 4 addresses the Significance and Use of this practice, including the legal context into which Phase II ESAs may fall. Section 5 discusses development and documentation of the scope of the Phase II ESA, including the Statement of Objectives for the assessment. Section 6 provides a Phase II ESA Overview, with purpose and goal descriptions. Section 7 comprises the main body of Performing the Phase II ESA, and includes initiating scientific inquiry by formulating the question to be answered (7.1), collecting and evaluating information (7.2), identifying areas for investigation (7.3), developing the conceptual model (7.4), developing a plan and rationale for sampling (7.5), conducting the sampling (7.6), and validating the conceptual model (7.7). Interpretation of results is covered in Section 8. Phase II Environmental Site Assessment report preparation is addressed in Section 9. Appendix X1 supports Section 4, and contains legal considerations pertaining to Phase II Environmental Site Assessment. Appendix X2 contains contracting considerations between Phase II assessor and user. Appendix X3 supports Section 9, and describes two examples and a sample table of contents illustrating possible approaches to reporting the results of a Phase II Environmental Site Assessment. Appendix X4 supplements Section 2 with a list of standards and references that may be relevant in conducting a Phase II Environmental Site Assessment.

1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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Book of Standards Volume: 11.05
Developed by Subcommittee: E50.02
Pages: 22
DOI: 10.1520/E1903-19
ICS Code: 13.020.30