The logic behind the site score given in the documentation record must comply with HRS rule. Otherwise it is arbitrary and capricious.
Misapplications of the rule or incomplete references can (and do) form the basis of legal challenges.
Professional judgment can be used if rationale and supporting documentation is provided; opinions can't.
EPA's defense of the site score is largely restricted to the information contained in the documentation record (HRS Guidance Manual page 27). Therefore, be sure that every HRS value is supported by documentation and reference citation showing that the value is reasonable and defensible.