Standard Recommended Practice for
Drilling for Subsurface Investigations•
Unexpectedly Encountering Suspected
AASHTO Designation: R 21-96 (2004)
1.1.This practice is intended to help protect drillers in the event they unexpectedly encounter suspected hazardous materials while performing subsurface investigations.
This is accomplished by training the drillers, identifying precautions to minimize risks of contamination, and
establishing a procedure to follow if suspected hazardous material is encountered. 1
1.2.This standard may involve hazardous materials, operations, and equipment.
This standard does not purport to address all of the safety concerns associated with its use.
It is the responsibility of the user of this procedure to establish appropriate safetyand health practices and to determine the applicability of regulatory
limitations prior to use.
2.1. AASHTO Standard and Publication:
Click below to download AASHTO Designation: R 21-96 (2004) pdf free
Click here to download AASHTO Designation:R 20-99 (2008) pdf free download