1. Scope

1.1 This practice defines various methods for assessing specific sites for potential adverse impacts that the presence of karst topography might have on site development, planned construction or site management. It is intended to offer various courses of actions that will provide a rational framework for planning and implementing a site characterization program to define potential karst conditions that might impact or be impacted by site development consideration for site suitability assessment.
1.2 This practice summarizes the various methods available for assessing the adverse impacts that karst conditions might have on planned site development, and the impacts that proposed development of the site would have to the karst resource and its intended use. Impacts to the resource would include impacts to water quality, water supply, cave, or aquifer fauna, and/or cultural or scientific resources. Karst impacts to site development would include collapse and subsidence potential, differential subgrade conditions (e.g.: rock, void, soft soils, etc.), non-uniform bearing, excavation difficulty, dewatering, etc. The goal is to identify the relevant conditions for consideration in site selection and design.
1.3 Final ranking of a site will fit in one of the following categories: (1) no evidence of karst features; (2); presence of karst features on the site which will not affect the planned use. (3) evidence of karst features that should be considered during planned development and construction.
1.4 Objectives guiding the development of this practice are (1) to synthesize and put in writing good commercial and customary practice for preliminary karst assessments, (2) to facilitate high quality, standardized preliminary karst assessments, (3) to clarify an industry standard for preliminary karst assessments in an effort to provide a protocol for these assessments to assist geologists, planners, engineers, and regulators in making an informed judgment on site development and management.
1.5 The use of this guide is limited to the scope as set forth in this section. However, the report might be of interest and useful to professional endeavors that the site characterization and report do not address. It is beyond the scope of this guide to include recommendations to any facet of the project design or construction processes. Any portion of the scope of this practice should be considered carefully if it is found in conflict with local ordinances or regulations. Such a condition would require a formal variance from the issuing agency.
1.6 This practice offers an organized collection of information or 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.
1.7 This standard does not purport to address all 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.
1.8 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026.
1.9 The procedures used to specify how data are collected/recorded or calculated, in this standard 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 standard to consider significant digits used in analytical methods for engineering design.
1.10 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.

Keywords

sinkhole; subsidence; karst; LiDAR; fracture trace; closed depression; karst hydrology; valley drain; sinking stream

Rationale

The assessment of karst conditions and putative karst geohazards prior to residential and commercial development is currently in its infancy, from a scientific aspect. Borrowing from the medical lexicon, most karst features at proposed building sites are dealt with using an approach wherein the “symptoms and conditions” are treated (e.g. sinkhole remediation), often only after site development activities have commenced. If karst hazards are suspected, roadways, foundations and specific at-risk areas may be investigated using various geophysical methods; however the results of these investigations require specialized knowledge to be interpreted and understood. Thus stakeholders without geological training may find the investigator’s results indecipherable, often leading to unnecessary and expensive supplemental studies, the need for which is entirely based on the non-technical stakeholder’s faith in the investigator’s judgment.

To address these concerns, we propose a proactive, “preventative” standard practice for karst assessments. Ideally, this proactive approach will help to delineate potential karst hazards so that they can be avoided, managed, or corrected by remediation. It is our hope that if carried out and reported accurately, the proposed assessments should allow even a non-technical stakeholder to make informed decisions regarding the relative risk of karst geohazards, the need for further studies, and potential corrective actions that site development may entail.

The title and scope are in draft form and are under development within this ASTM Committee.