Purpose: This manual implements the USACE policy and requirements on validation of analytical chemistry laboratories as prescribed in the USACE Engineer Regulation 1110-1-263. This manual provides detailed procedures, guidance, and criteria for validation of commercial and USACE Division analytical chemistry laboratories. Laboratory validation is required to ensure that analytical chemistry laboratories meet the minimum requirements of the USACE quality assurance/quality control program that facilitates the generation of chemical data of known and acceptable quality.