The developers of Rossmoor Leisure World, the massive retirement community in Montgomery County, said in a lawsuit filed last week that the county and three government agencies should pay them $29 million for land used and delays caused by construction of an "unnecessary" sewage treatment plant on their property.

The developers were forced to build the plant or face "economic ruin" because of a 1973 ban on sewer connections by a state agency, according to the suit.

The developers of Rossmoor charged that the Washington Suburban Sanitary Commission (WSSC) ignored a 1965 agreement it had signed to provide water and sewer service to the community when the Maryland Department of Health and Mental Hygiene ordered the WSSC to halt sewer connections in 1973.

In the lawsuit filed in U.S. District Court in Baltimore the developers charged that the sewer moratorium itself was "wrongfully, arbitrarily and capriciously" ordered by the state agency. The moratorium halted the planned development of the community, where about 2,200 residents lived in 1973, and forced the developers to either build their own sewage treatment facility or face "economic ruin," according to the lawsuit.

The developers did build a system on a 243-acre site that also provides service to areas outside Rossmoor, according to the suit. Now the Rossmoor Corp. of California and Rossmoor Construction Corp. in Silver Spring wants the county and other agencies to pay more than $19 million, which they assert is the fair market value of the 243-acre site.

The developers charged that in a 1974 meeting with Montgomery County, they were advised that their sewage treatment plant would have to absorb part of the sewage load from the general public as a "quid pro quo" for approval of its application to build the sewage plant.

Also named as a defendant was the Maryland-National Capital Park and Planning Commission, which allegedly was involved in a approval of the county sewage plan that involved the Rossmoor facility.

None of the defendants could be reached for comment.