Eric Romandi, 61, of New Milford, pleaded guilty to a similar conspiracy charge.
Galietti was a lead salesman at Automated Waste Disposal and affiliated Danbury-based companies operated by James Galante. Romandi served as general manager and the companies' route supervisor.
They both helped perpetuate a system with other carting companies in which carters agree not to service or compete for other's customers, prosecutors said.
The government said the scheme, directed at commercial and municipal customers, destroyed free enterprise, allowing the participating carters to artificially inflate their prices and leaving waste removal customers with no options other than to pay.
Galietti convened meetings with competitors to quell potential price wars, had competing carters "locked out" of transfer stations, bullied customers seeking to obtain more favorable rates, threatened noncompliant carters with violence and, in one instance, damaged the property of a competitor, prosecutors said.
Galietti also admitted that he asked his cousin, who was a Connecticut state police trooper, to run license plate information through a law enforcement database to determine whether Galietti and his associates were under investigation.
Romandi told witnesses to lie about the scheme, and about payroll kickbacks paid to Galante, prosecutors said.
Charges were eventually filed against 33 individuals and 10 businesses. Most, including Galante, have pleaded guilty.
Prosecutors alleged that Galante, who awaits sentencing, paid $30,000 each quarter to alleged Genovese crime family boss Matthew "Matty the Horse" Ianniello in exchange for mob muscle to stifle competition. Ianniello pleaded guilty to racketeering conspiracy and tax evasion and was sentenced to two years in prison.
Romandi faces a maximum of 25 years in prison and a fine of up to $500,000 when he is sentenced on Oct. 17.