AASHTO R 22-97 (2019) PDF Download

The AASHTO R 22-97 (2019) standard provides guidelines for the permanent closure of various types of geotechnical exploratory boreholes. The standard specifically focuses on situations where hazardous materials or solid wastes are not present. The types of boreholes covered include those with temporary casing, uncased boreholes using drilling mud or open-hole techniques, hollow-stem flight auger boreholes, observation wells, instrumentation boreholes, cone penetrometer boreholes, and soil characterization test boreholes.

The standard outlines a systematic approach for decommissioning these boreholes, beginning with an evaluation of site characteristics and potential problems. It then discusses the review and selection of decommissioning options, including the option of not decommissioning if applicable. The standard also provides guidance on selecting an appropriate sealant and method of sealing the borehole. Quality control and performance requirements for the sealed borehole are addressed, as well as record-keeping requirements.