Carrolltowne, a 700-unit planned residential community in southeastern Carroll County, Md., has been honored by the American Consulting Engineers Council for the community's storm water management facility. Special praise was given to an earthen dam sculptured from existing topography. Commercial Credit Development is the developer. Century Engineering Inc. designed the system.

Two rental buildings in the 1,051-unit Grosvenor Park high-rise complex in upper Bethesda are being marketed for condominium ownership by Grosvenor Park Sales Inc., representing Rockville Grosvenor Inc., a wholly owned subsidiary of American Invesco Corp. A preferential sales program for tenants has been set up. The third (south) of three high-rise Grosvenor buildings was converted to condominium ownership several years ago.

Written examinations for real estate brokers and sales persons in the District will be May 21 at the Shoreham Americana, beginning at 8:30 a.m.

A commerical leasing seminar sponsored by the Washington Board of Realtors will be Wednesday, beginning at 9:30 a.m., at the Mayflower.

The law firm of McGuiness and Williams has leased 28,565 square feet of space in an office building being completed at 1015 15th St. NW by the John Akridge Co. Shannon & Luchs handled the leasing negotiations for the total $4 million contract.

The Potomac area chapter of the American Right of Way Association will hold a seminar Tuesday at the Turf Valley Country Club in Ellicott City, Md.

Informatics Inc. had leades 29,696 square feet of space in the new 1776 Plaza complex in W. Rockville for six years for $1.7 million. The Julien J. Studley firm arranged the lease with the firm that has a government contract to do research on alcohol and drug abuse. Irving D. Berger is the owner of the 1776 complex.

Walker & Dunlop has been named leasing agent for the Plaza 270 Office Center being built at 1600 Research Blvd., Rockville. Two building will have a total a 160,000 square feet. Holle & Graff designed the buildings.

The 22d annual Capitol Hill Home and Garden Tour will be Sunday from 1 to 6 p.m. Ten homes will be viewed. Tickets may be purchased Sunday at the Eastern Market, where the tour will start. For information, dial 5446048.

The metropolitan area chapter of the Mortgage Bankers Association will meet May 22 for lunch at Hogate's, where Cecil E. Sears III will be the speaker. He will discuss MBA educational programs.

The Apartment and Office Building Association will hold its annual roundup program at a showing of new products on May 23 beginning at 11:30 a.m. at the Ramada Inn in Rosslyn.