The following were among actions taken by the Alexandria City Council at its Sept. 22 meeting. For further information, call 838-4300.

POTOMAC RIVER DREDGING -- The council voted 6 to 1 to ask Rep. Stan Parris (R-Va.) to urge the U.S. Army Corps of Engineers to dredge the Potomac River channel so it will allow better access for commercial and tourist ships seeking to dock in Alexandria.

Parris represents Virginia's eighth congressional district, which includes Alexandria. Councilmember Robert L. Calhoun voted against the request, but did not say why.

The channel, which runs down the center of the river to provide ships access from the Chesapeake Bay to Alexandria, was last dredged to a depth of 24 feet in 1967 by the Army Corps of Engineers. The federal government is responsible for the river's maintenance.

The 24-foot channel clearance is now less than 19 feet deep at some spots, Alexandria City Manager Vola Lawson said in a memo to the council distributed in preparation for the meeting.

"This means that many commercial ships can no longer reach Alexandria," Lawson said in the memo. "This also affects larger cruise line ships and guest military ships" that need to dock in Alexandria, she said.

It would cost $8.7 million to dredge the channel to 24 feet, if the dredged material is deposited elsewhere in the river, Lawson said. It could cost as much as $21.8 million, if dredged materials are hauled out of the river and deposited on land.

In the letter to Parris, Lawson said one reason the city is concerned about the channel is because the city has "already had larger cruise ships refuse to return to Alexandria because of poor maintenance of the {river} channel."

GYPSY MOTH SPRAYING -- The council voted 6 to 0 to implement a $52,823 program next spring to kill gypsy moths that are defoliating trees in the north central part of the city at an increasing rate.

The number of gypsy moth egg masses in some neighborhoods has doubled since last spring, according to City Arborist Jennifer Hollings, whose office periodically measures the egg masses.

The program, which will begin in late April or early May 1988, will use a helicopter to spray a pesticide on the trees. The city also will hire a part-time program coordinator to oversee the spraying.

The city plans to apply to the Virginia Department of Agriculture and Consumer Services for financial and technical assistance.

Gypsy moth caterpillars, which eat the leaves of trees, killing some, were first sighted in Alexandria in 1982, according to a study conducted by the city arborist's office. The moth population remained the same until this spring, when the city received twice as many reports of moth egg masses in the Beverley Hills neighborhood than there were last spring.

The city will spray the pesticide Dimilin on trees in a 1,700-area area of the north central part of the city where the moth caterpillars have caused the greatest damage to trees. The area includes the neighborhoods of Beverley Hills, Seminary Heights, Parkfairfax, Warwick Village, Piney Court and the Virginia Theological Seminary grounds.

The arborist's office will hold a public meeting Nov. 9 to answer citizens' questions about gypsy moths on Nov. 9. The location of the meeting will be announced later.