The Miami-Dade Ethics Commission found no probable cause Thursday to support a complaint against a lobbyist who submitted supplemental documents to a selection committee reviewing proposals from would-be contractors bidding to oversee $1.2 billion in repairs to the county sewer system.

Los Angeles-based AECOM Corp. complained a rival company, Colorado-based CH2M Hill Inc., violated county bidding rules when attorney-lobbyist Mitchell Bierman added a 400-page document to its original presentation just before a second phase of the evaluation process. The commission unanimously found the late submission was not “specifically prohibited” by the bid documents.

The decision follows a staff report that concluded the so-called cone of silence ordinance did not bar such submissions.

Since the controversy arose, county procurement officials have amended procedures to bar direct communications with selection panel members on future bids.