Yes and no; legally, anyone can conduct a Phase I ESA. However, if you want your assessment to meet the ASTM standard, then the “environmental professional” you use will need to provide documentation that they meet the specific qualification requirements contained in ASTM E 1527-13. The ASTM specifies the professional qualification, education and experience needed to qualify as an Environmental Professional.
Different organizations and lenders may have additional requirements on who can conduct Environmental Site Assessments they will accept. For example, the Small Business Administration (SBA) requires that the environmental professional has a minimum of $1,000,0000 professional liability insurance, in addition to meeting technical qualifications.