ONLINE SUBMISSION VIA PHMSA PORTAL IS REQUIRED UNLESS AN ALTERNATIVE REPORTING METHOD IS GRANTED BY PHMSA.
PHMSA Portal https://portal.phmsa.dot.gov/portal
See Online Submission Registration Requirements at http://opsweb.phmsa.dot.gov/portal_message/PHMSA_Portal_Registration.pdf:
If electronic reporting imposes an undue burden and hardship, an operator may submit a written request for an alternative reporting method to the Information Resources Manager, Office of Pipeline Safety, Pipeline and Hazardous Materials Safety Administration, PHP-20, 1200 New Jersey Avenue, SE Washington DC 20590. The request must describe the undue burden and hardship. PHMSA will review the request and may authorize, in writing, an alternative reporting method. An authorization will state the period for which it is valid, which may be indefinite. An operator must contact PHMSA at 202-366-8075, or electronically to email@example.com or make arrangements for submitting a report that is due after a request for alternative reporting is submitted but before an authorization or denial is received. Operators should request and receive authorization from PHMSA prior to the use of alternative reporting methods.