Two days after the National Public Radio board voted last week to continue weekend broadcasts of "All Things Considered," the struggling network received a $100,000 grant from Waste Management Inc. for the news show. The grant will enable NPR to lower the one-year fees its stations had pledged for the program and perhaps enlist more stations to take the weekend show.

In the spring, at the suggestion of its member stations, NPR drew up a fee schedule to determine whether enough stations were willing to pay for weekend "ATC," as well as for other arts and performance programs for the next year. The Corporation for Public Broadcasting had announced earlier that it could give NPR 1.3 million in fiscal 1986 but NPR felt that amount would not cover the two services. Last week the NPR board announced that a combination of station fees and outside underwriters would enable them to continue the services. With the Waste Management grant NPR now has about $450,000 of the $500,000 estimated budget for the news program, which attracts 800,000 listeners each week. In the arts and performance area, NPR said 217 stations had pledged $340,000 of the $661,000 needed. The network said it would continue to solicit funds from private donors for these programs, which are used by 98 percent of public radio stations. Let's Get Personal

Starting Aug. 4, WHFS-FM (99.1) plans to read "personal" notices submitted by listeners from 10 p.m. to 4 a.m., the Annapolis outlet announced this week. Around the country dating talk shows have cropped up in recent years but industry observers don't recall a station running a paid service similar to the "In Search of" ads in Washingtonian magazine and similar publications. In a recent survey of its listeners, WHFS found that 93 percent of its audience is between 18 and 34 years of age, and 55 percent of its audience is single. The station is asking that "personals" be 75 words or less and will charge $50 for four consecutive nights of readings. Job Switches

WWDC-FM/AM (101.1/1260) this week gave three employes additional duties: Dave Brown, an announcer on the AM/FM and music director for FM, is now also vice president for programming; B.J. Cohen, promotions director for AM and FM, is now also assistant program director for FM; Bill Scanlan, production director for AM and FM, is now also assistant program director for AM . . .Bill Cellers, most recently of Wheeling, W.Va., joins WPKX-FM (105.9) from midnight to 5:30 a.m. . . . David Creagh, an NPR board member who is the former manager of a Long Beach, Calif., public station, has been named general manager of WJHU-FM at Johns Hopkins University. Park Sounds

Every Tuesday and Wednesday until Aug. 14 WDJY-FM (100.3) is participating in the D.C. Recreation Department's "Munch a Lunch" live music series at noon, giving away T-shirts, soft drinks and bumper stickers. On Tuesdays: Pershing Park, 14th and E streets NW, and Wednesdays: McPherson Square, 15th and K streets NW. 'Spirits' to Continue

The training workshop that has produced "Spirits Known and Unknown" for WAMU-FM (88.5) for the last 14 years will continue despite the reduction of the Saturday show to 30 minutes of news and information. As many as 300 people have participated in the production workshops, which are believed to be unique in broadcasting. "The station cut back the music portion because our numbers showed we weren't competing well against WPFW and WDCU," said David Muse, the show's host for the last four years. "And also it didn't go with the rest of the station's format." WAMU has said it plans to increase technical and personnel assistance to the show, which now starts at 5:30 p.m. So Others Might Eat

Trumbull and Core of WMAL-AM (630) raised $15,000 in four hours for the So Others Might Eat senior citizen camp . . . WOL-AM (1450) and a host of record executives and colleagues, raised $10,000 for Al Jefferson, longtime promoter who is retiring. The annual celebrity softball game between WMAL and WDVM (Channel 9) raised $2,000 for the Latin America Youth Center; WMAL won 22-12 . . . Gary Murphy and Carol Parker of WRQX-FM (107.3) helped raise $1,200 for the Sunshine Foundation recently. Gospel Editorial

Joining the staff of WUST-AM (1120) is the Rev. Imagene Stewart, founder and director of the House of Imagene, a women's shelter, and national chairwoman of the American Women's Clergy Association. Her two-minute comments start Thursday and will be aired daily at 9:15 a.m. Lavern Jackson, the station manager, said Stewart was selected to provide a nonpartisan view of local issues. The station already carries a report from D.C. City Council Chairman David Clarke and a report from Mayor Marion Barry's press office. Dance Card Requests

WKYS-FM (93.9) is cosponsoring Family Fun Day tomorrow on the Washington Monument grounds. At 2 p.m. there will be a "Putting on the Hits" contest for look-alikes and dance-alikes of the famous . . . Gary Alan of WASH-FM (97.1) will host the Turtles and Gary Lewis at Wild World tomorrow at 5 and 7:30 p.m . . . WBMW-FM (106.7) will present a check for $20,000 from the ticket sales of the Rick Springfield concert tomorrow at Constitution Hall at 8 p.m. to Students Against Drunk Driving of the Fairfax County area . . . WMDO-AM (1540) will broadcast from the Hispanic Festival along Columbia Road NW Sunday, sporadically from 1 to 3 p.m. and continuously from 3 to 7 p.m. . . . Trumbull and Core will be broadcasting live from the Redskins' training camp at Carlisle, Pa., Tuesday beginning at 3:05 p.m. . . . WWDC-FM and its mad morning man, Greaseman, will do a remote Thursday from the Hyatt Regency on Capitol Hill from 6 a.m. to 10 a.m. . . . For a discussion of safety on the Potomac River, Jim London and Mary Ball of WMZQ-FM/AM (98.7/1390) will broadcast from Great Falls Park in Virginia Friday from 5 to 10 a.m.