The Ivor B. Clark Co. Inc. has arranged joint-venture financing of $7.7 million for the first phase of Cascades Center, an office park at Sunrise Valley Drive and Reston Avenue in Reston.

The four-story steel frame structure with a brick facade will have 100,000 square feet that Clark's Elliott Kocen said has been leased to Advanced Technology Inc. for its national headquarters. The consulting firm is a major marketer of information and energy technology.

The Cascades Center, which will be built around connecting ponds and waterfalls, will have two other similar-sized buildings. Christopher Walker of Dupree District Associates is the developer. Davis, Smith, Carter & Rider is the architect. Tiber Construction is the builder. Completion is scheduled next spring.

Leggat McCall & Werner announced these leases: 11,668 square feet in the new national headquarters of the National Cable Television Association building at 1724 Massachusetts Ave. NW. to AT International, with Shannon & Luchs participating; 9,182 square feet to the law firm of Harris, Berg & Cresskoff at 1100 15th St. NW., a building now nearing completion by Prudential Life Insurance Co., with Braedon Companies participating, and 5,317 square feet at Capital Gallery at 600 Maryland Ave. SW to Millers National Federation, which represents wheat four millers.

A mid-summer completion is scheduled for the 100,000-square-foot headquarters building being constructed for John Hanson Savings & Loan at 11700 Beltsville Rd., off I-95 near Calverton. The six-story building is being done by Glenn Construction. Walton, Madden and Cooper designed the building. Leasing is being handled by Cushman-Wakefield. The S&L plans to keep a branch office at its present headquarters at 7610 Pennsylvania Ave.

H. G. Smithy Co. announced it arranged for the International Bank for Reconstruction and Development World (World Bank) to take an additional 37,000 square feet a 1825 K St. NW., beginning next week. Smithy also arranged for the law firm of Smith, Heenan, Althen & Zanoli to relocate to 6,500 square feet at 1110 Vermont Ave. NW and for NBC to occupy 8,500 square feet at 1825 K in June.

Ted Manousakis recently started a small office building at 1023 31st St. NW with a $2.25 million loan from Union Labor Insurance Co. Manousakis is the owner-operator of the Henry Africa restaurant in Old Town Alexandria.

Danac Associates Inc. has been chosen to hangle leasing of the new Smallwood Village shopping center in St. Charles, an 8,500-acre community in Charles County, Md. The 153,000-square-foot shopping center has 50 retail and office spaces in a two-story brick building with cedar shake roof and archways. A Safeway already is in operation at the site at St. Charles Parkway and Post Office Road.

Black's Guide, an annual reference book on the office-space markets, has named Brooks R. Sheifer publisher of the Baltimore-Washington edition. The New Jersey-based firm has its area office in Bethesda. The Black books contain comprehensive listings of available office space and information on office leasing markets.