The Hyattsville City Council unanimously rejected this week a Washington Suburban Sanitary Commission proposal to expand its headquarters in Hyattsville.

At the urging of more than 1,100 residents, who signed petitions opposing the plan, and after several people voiced opposition at a public hearing last week, the council told the WSSC to find another way to enlarge its Hyattsville administrative offices.

The WSSC recently proposed a five-story addition to its building on Hamilton Street in Hyattsville. The addition, which would cost $4 million, according to John Kastanek, WSSC project manager, was one of three expansion options the commission was considering.

Kastanek said that because of the unanimous vote, "the proposal for the five-story expansion is dead. We will now have to look for a different site away from the area or just continue leasing."

The WSSC has been trying to expand its four-story building since 1969, when officials first proposed the vertical extension. But neighborhood opposition combined with budgetary restrictions curbed the idea.

"We thought we'd try again," Kastanek said, "so we did the simplest thing and asked the City of Hyattsville for their approval.

The city appointed a citizens advisory committee in June to study the WSSC expansion. Last week the committee voted overwhelmingly to oppose the project. Ed Fizdale, a committee member who lives across the street from the WSSC building, said that additional employes would increase traffic and parking problems in the area, and the visual effect of a nine-story building would disrupt the residential character of the community.

Because the headquarters building is in the heart of the residential area, residents bitterly opposed the idea of what they said would be a high-rise in their midst.

Kastanek said the WSSC would begin looking at sites in Prince George's and in Montgomery counties for a new building to house all of the 700 employes on the administrative staff. Currently 500 employes work at the headquarters building in Hyattsville and 200 work in leased space in the Presidential Building in Prince George's Plaza. Kastanek said the WSSC pays approximately $500,000 to rent the facilities, including transportation costs to an from Hyattsville.

The expansion of the headquarters would have been the cheapest way to consolidate all of the WSSC's staff under one roof. Kastanek said the expansion would cost $4 million compared with a consultant's estimate in 1973 of $12 million for a new building.

Hyattsville officials said they would prefer that WSSC remain in the city. "There is plenty of room to expand using their present building and other sites in Hyattsville," said Mayor Jeremiah Harrington. "Hyattsville needs some help for its downtown."

County Council member Parris Glendening, who attended the meeting as an observer, said he plans to send a letter to WSSC General Manager Robert McGarry suggesting that the WSSC consider purchasing a county-owned site in downtown Hyattsville, next to the County Services Building.

"We plan to build a parking garage behind it, and we could add a floor if we knew WSSC would build there," Glendening said. "That's only three or four blocks away from the existing offices."

Tony Pauletti, another Hyattsville resident actively opposed to the expansion, said a relocated WSSC headquarters in Hyattsville would be an economic boon to the area.

"A building downtown would help revitalize the commercial area."

Kastanek said the commission would prefer to be "closer to the beltway or closer to the bicounty line. We have six prime sites located in both counties, and are open to suggestions from anyone."