ASTM D8658/D8658M-26

5.1 This guide is intended to assist qualified professionals in conducting a detailed karst site investigation, specifically if the results of a preliminary karst survey (Practice D8512-23, 7.5) indicate that karst features will or could impact or be impacted by development. The detailed site investigation will provide relevant information on one or more of the following subjects:

5.2 Location and extent of subsurface karst development, both horizontally and vertically, for features that may impact, or be impacted by the proposed construction including surface and subsurface structures, utilities, roadways, and stormwater management areas.

5.3 Determination of site hydrology and its potential for impacting water sources such as sinkholes (karst windows), springs, wells, and streams.

5.4 The detailed site investigation may require the collection of sufficiently large soil and rock samples of such quality as to allow for adequate testing to determine the soil and rock classification or mineralogic type, or both, and the engineering properties that may be pertinent to the proposed design.

5.5 This standard guide is not meant to be an inflexible description of requirements; methods defined by other ASTM standards or non-ASTM techniques may be appropriate in some circumstances. Karst investigations rely on multiple partial data sources; no single method provides complete characterization. Subsurface variability should be assumed and the risks associated should be managed proportionally to the proposed development.

5.6 This guide is intended for the characterization of karst features and terrains formed by soluble bedrock (that is, carbonate and evaporite rocks) and does not address the characterization of pseudokarst features or conditions. Unlike karst features formed by dissolution, pseudokarst features are created by volcanic activity, erosion, or subsidence rather than chemical dissolution.

5.7 The intent of the detailed site investigation is to assist in the collection of sound, scientifically valid data concerning karst conditions that may impact site development, regardless of whether or not these conditions were identified during the Preliminary Site Assessment carried out in accordance with Practice D8512. The findings should be incorporated into a final report which will assist the developer or their agents in preparing a karst management plan for both the construction phase of development and the life of the facility.

Note 1: The quality of the result produced by this standard is dependent on the competence of the personnel performing it and the suitability of the equipment and facility used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing/sampling/inspection. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some, but not all of those factors.

Note 2: If unstable subsurface conditions are encountered and indicated in the detailed site investigation, a decision can be made to: (1) remediate/mitigate the instability prior to construction or (2) to modify the site layout to avoid problem area(s). Because of the high likelihood of encountering issues in karst, the earlier in the planning process that the detailed site investigation is performed, the better.

1.1 This guide refers to ASTM methods to perform a detailed site investigation in karst terrain for engineering, design, construction, and groundwater evaluation purposes. The scope of the investigation should reflect the size and complexity of the development project, the preliminary site plan, and the requirements of the jurisdictional plan review authority. No single investigative approach works in every location. The sequence begins with a visual assessment of diagnostic karst features, and analysis of subsurface heterogeneity through geophysical investigations, geotechnical investigations, and hydrological characterization conducted under the direction of a qualified professional with experience working in karst terrain. All references in this guide to the “qualified professional” refer to individuals (such as engineers, soil scientists, geophysicists, engineering geologists, or geologists), who have the appropriate experience and, if required by local regulations, applicable certification, licensure, or registration. The term “engineering” must be understood as associated with the practices or activities of that qualified professional.

1.2 Laboratory testing of soil, rock, and groundwater samples is specified by other ASTM standards not listed herein.

1.3 In addition, the location and nature of underground and overhead utilities should be identified to ensure that there is no impact to the proposed site characterization. Impacts may include but are not limited to interference with geophysical methods, damaging utilities, creating unsafe work conditions, and limiting accessibility for exploratory equipment.

1.4 Units—The values stated in either SI units or inch-pound units are to be regarded as the standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. Inch-pound units are provided in brackets for convenience.

1.5 This standard offers an organized collection of information as a series of options and does not recommend a specific course of action. This document cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this guide may be applicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this document be applied without consideration of a project’s many unique aspects. The word “standard” in the title of this document means only that the document has been approved through the ASTM consensus process.

1.6 Uncertainty cannot be eliminated in karst terrain; investigations reduce but do not remove risk. Findings should be interpreted probabilistically, and design should include contingencies for unanticipated conditions.

1.7 Regional empirical indices used for sinkhole vulnerability assessment are beyond the scope of this guide.

1.8 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026.

1.9 The procedures used in this guide to specify how data are collected/recorded or calculated are regarded as the industry standard. In addition, they are representative of the significant digits that generally should be retained. The procedures used do not consider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the user’s objectives; and it is common practice to increase or reduce significant digits of reported data to be commensurate with these considerations. It is beyond the scope of this guide to consider significant digits used in analysis methods for engineering design.

1.10 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.11 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.