A federal grand jury today indicted the former chief executive of a sludge-hauling firm on charges of conspiring to pay at least $10,000 in bribes to former Baltimore City Council president Walter S. Orlinsky in exchange for lucrative sludge disposal contracts in the city.

The 10-count indictment charges Douglas T. Murray and his Modern Earthline Companies of Philadelphia, as well as a local affiliate called Modern Earthline Companies of Maryland, with a wide range of interstate racketeering, conspiracy and wire and mail fraud violations.

According to the indictment, Murray, using a middleman, made four payments to Orlinsky totaling $10,000 between December 1980 and June 1981, with a promise of more to come.

Orlinsky was indicted last year on charges of receiving $10,000 in kickbacks and pleaded guilty in September to a single count of extortion. He resigned from the City Council presidency and was sentenced to six months in prison. He is currently at a federal prison farm in Allenwood, Pa.

An FBI spokesman said the investigation is continuing "with an eye toward additional prosecutions."

In today's indictment, Murray and his companies are charged with seeking a two-phased contract with Baltimore in 1980 by bribing Orlinksy to use his influence to get city officials to approve the contract.

An initial $500,000 pilot phase of the contract was approved for hauling city sludge to Garrett County in western Maryland. Garrett County officials objected to the arrangement, however, and a second long-term, $46-million contract was canceled.

Federal investigators say that if the second contract had gone through, Orlinsky stood to share with other, unspecified public officials in nearly $1 million in additional kickbacks.

The indictment says that Murray made the four payments totaling $10,000 to Orlinsky through Edward J. Russell, a lobbyist for Modern Earthline in Maryland. Russell cooperated with federal prosecutors Richard E. Dunne III and Stephen J. Immelt in the case and has not been indicted.