For the last five years, the Montgomery County's Office of Enviromental Planning has steadily expanded roughly in proportion to the county's mounting pile of sewage and refuse disposal problems. Like the rest of the government bureaucracy, its annual expansion has been almost automatic.

Next year, OEP's responsiblities will continue to grow, but for the first time, its staff will not. A costconscious Montgomery County Council tentatively approved OEP's budget for 1980 on Monday night, and deleted one vacant position from its staff.

The hold-the-line budget, which gives OEP $1.50 out of the average property taxpayer's $1,050 annual bill, provides a clear illustration of the effect las t fall's tax-cutting debate had on next year's budget.

And as far as OEP staffers are concerned, the county's taxpayers probably won't notice the difference, sincemost county residents have little to do with the agency. For those that do, the slight cuts probably will slightly increase bureaucratic delays.

"The average citizen won't notice, unless he has a specific problem with the government," said Linda Fohs, an OEP planner.

OEP is one of about 125 separate offices now appearing before the Montgomery County Council to justify thier need for a portion of County Executive Charles W. Gilchrist's proposed $598.5 million budget for 1980.

For the first time in 15 years, Gilchrist's "hold-the-line" recommendation reduced the actual number of central government jobs from 5,295 to 5,253.

The Proposition 13 mentality that dominated the fall elections resulted in "a much greater sense of cost-consciousness," said new council member Scott Foster. "It has made it more legitimate to question why we need to do some of the things are doing in government. I think this year you could say we are beginning some intelligent paring."

One of Gilchrist's methods to trim government's size was to impose a county-wide hiring freeze when he took office last winter. The most critical problem this posed for David G. Sobers, the director of OEP, was the three empty desks in the office as he began budget preparations for 1980.

For Sobers and the OEP, those vacant slots meant that fewer people performed more work, unanswered mail piled higher and some projects actually were set aside. "Give that enviromental problems are only becoming more complex, it takes time to understand the issues and develop solutions," Sobers said. "The more mental power we can apply, the more we can get accomplished."

The Office of Enviromental Planning is responsible for planning what to do with 1,300 tons of trash and 69.7 million gallons of sewage that the county's 590,000 residents generate each day. Its staffers also are influential in determining who can develop land and who cannot, where residents find their drinking water and how dwindling energy supplies can be conserved.

At any one time, the office is working on about 17 plans and reports designed to give the county executive and the county council some basis for enviromental policy decisions. Last year, for example; they produced a 209-page energy management plan for the county government and completed a $2 million landfill site selection process that required more than 100 mettings, hearings and technical studies over the course of two years.

"It would be nice to fly over the county and say we should put a landfill there," said Ted Graham, a 35-year-old Ph.D. "But in Montgomery County, decisions are not made that way. Site selection is a laborious process. You get fought by the citizens every step of the way. You have to be able to document eyerything."

Enviromental planners, whose jobs were greatly expanded by the spate of new U.S., state and local laws produced by the enviromental consciousness of the 1960s, are fundamentally problem-solvers.

When deciding where to build new sewer lines, they will plot each step of the process-from failing septic systims to sewage flowing through new pipes-on a time chart that covers several years. Every step of the way the chart notes the proper time for a health permit application, or engineering consultant study or county council policy vote.

The staff occupies 13 small offices on the fifth floor of the county government office building in Rockville. Most of the staff are in their 20s or 30s, although Louis Peltier, a former geography professor, is 62. Sobers wears suits and monogrammed custom-made shirts. Some staffers show up in boots and jeans.

In 1978, they used 17 dozen yellow pads, 26 dozen pencils and 14 dozen marker pencils to draw the color-coded maps that illustrate their numerous public presentations.

When Sobers began preparing the office's 1980 budget requests last fall, he tallied up a mental wish list: four more planners, expanded office space and 15 to 20 percent salary increases to compete with comparable federal jobs.

He also would have installed automatic typewriters and pushbutton telephones. The probable bill for all of this would have totaled about $150,000.

"But I recognized the reality of things," said Sobers, a 10-year local government veteran. In submitting his request to the budget office, he settled for far less-one less planner than, in theory, he already had and an 8.25 percent pay increase for his staff through cost-of-living adjustments and merit system increments.

His budget for next year almost certainly will total $494,690-about $10,000 less than last year's.

The largest single budget item, after salaries which range from $10,000 to$37,700-is printing. About $19,800 in printing costs is budgeted for the documents the office produces.

Last fall, in anticipation of a tax-payers revolt the county council established strict budget guidelines that permitted county department heads to submit budget proposals that would raise spending by no more than 3 percent.

Immediately, officials in the Department of Community and Economic Development, of which OEP is a part, realized "that we were going to have to cut positions," said Peter Hutchinson the department's budget analyst.

So Hutchinson asked Sobers, who directs one of six departmental offices, to relinquish one position. Sobers gave up the slot set aside for someone to plan a newspaper collection system for the county. No one in Sobers office held that post at the time it was eliminated.

In return, Sobers was given permission by budget officials to fill the three vacant slots for which he now is recruiting.

OEP's budget proposals were sent to the budget office, which incorporated the recommendations into County Executive Gilchrist's budget with no substatial changes.

County developers complain that, no matter how much or how little money the office has, problems still don't get solved.

As land development engineer Joseph Rodgers said recently, "we've been in and out of sewer moratoriums for eight years, and Sopers' shop is the office responsible for getting us out of that . . . We don't solve problems in the county office building, we talk about them."

Monday night, the council assembled for its 18th budget work session in three weeks. "This budget I have simply left as submitted,' stated Council Member Esther Gelman, assigned to review the OEP budget for the rest of the council.

No council member said a word "this budget is approved as submitted," Council Prisident Neal Potter declared. Sobers and Graham cast weary eyes toward each other and collected their papers and went home.* CAPTION: Graph, One Agency's Budget, The Washington Post