Section 324 of EPCRA addressing the public availability of documents, states that the emergency response plan, material safety data sheet or list submission, Tier I/II, Form R and Section 304 written follow-up notice are to be made available to the public by "the State Emergency Response Commission (SERC), or Local Emergency Planning Committee (LEPC), as appropriate," (Section 324(a)).

Can this be interpreted to mean that the documents can be made available by the SERC or LEPC as long as all the mentioned documents are made available by one or the other?

What Section 324(a) is addressing by saying the SERC or LEPC can make documents available as appropriate is the instance where a form may be submitted to one and not the other.  For example, the LEPC does not receive Section 313 Form R submissions.  Therefore, it would not be appropriate for the LEPC to make Form Rs publicly available. 

Therefore, EPA has interpreted Section 324 to mean that both the SERC and LEPC must make publicly available all the above documents that are submitted to them.