A Baltimore federal grand jury yesterday returned a conspiracy indictment against the founders of a Washington construction business, charging they posed as a minority-controlled small business in order to obtain a $2.5 million Navy construction contract.

The firm, R&W Construction Inc., also has done major amounts of work on Metro projects under subcontracts awarded to minority businesses.

Charged in the three-count indictment were Raymond L. Rice and Jesse G. Williams, two black former construction company employes who incorporated R&W in 1972 as a front for a white-owned construction firm. Excavation Construction Inc., according to the indictment.

In fact, according to the indicatment, R&W was created by Excavation Construction and its two owners, John W. Lyon and Larry A. Campbell, "solely for the purpose of obtaining federally funded contracts, which required participation of companies controlled by minorities and goverment contracts that had been set aside for small businness concerns."

Campbell and Lyon, who alwo is general manager of Parking Management Inc. (PMI), were not indicted. Assistant U.S. Attorney Robert A. Rohrbaugh said yesterday that the investigation is continuing.

According to sources outside the U.S. attorney's office, the investigation extends to other aspects of Excavation Construction's activities and other affiliated companies.

The indictment was the second criminal indictment in three months mentioning Excavation Construction. In October, former local Teamster official Frank DeBrouse was indicted for extorting money and favors from a number of companies with which the Teamsters had contracts, including Excavation Construction.

The construction company, which is a major Metro contractor and one of the largest heavy construction businesses in the area, also has figured in two other recent investigations. One involves allegations that a D.C. Superior Court Judge suspended or revoked fines for hundreds of overweight truck tickets issued to Excavation Construction, the second is a Montgomery County investigation of the murder of the president of an- other Excavation Construction subsidiary.

Yesterday's indictment centers on a 1976 Navy contract to shore up land at a constructionsite at the U.S. Naval Academy in Annapolis. The contract had been set aside for bids by small businesses and which required participation by minority-controlled enterprises.

According to the indictment, Rice and Williams bid for the contract claiming that R&W was a small business and was not controlled by any other company.

Both statements were false, according to the indictment. Rice and Williams "well knew" that R&W was actually controlled by Excavation Construction and that Campbell and Lyon formulated, determined and vetoed the "basic policy decisions" of R&W, the U.S. grand jury said.

They also knew that when R&W's average annual receipts for the three preceding fiscal years exceeded $12 million, when combined with Excavation Construction's earnings. One of the guidelines for determining what is a small business is whether the business's receipts exceed that figure.

Before they signed the articles of incorporation for R&W, both men worked for Excavation Construction, Rice as a shop superintendent and Williams as a truck driver, the grand jury said.

According to other court documents, Rice worked for Campbell as early as 1964, when Rice was a truck driver for C&E Excavating, a defunct firm in which Campbell was a partner.

Rice, reached at R&W yesterday, said he not been informed of the indictment. "I don't have anything to talk about," he said, when asked about some of the charges.

Rice is now said to be the sole stockholder in R&W, which is currently working on the Rockville Metro route as a subcontractor for Ohio Valley Construction Co.

Metro had certified R&-W as a minority company qualified to do business with the transportation agency on the basis of affidavits similar to those Rice and Williams signed on the Naval Academy project. According to a recently submitted affidavit, Rice has owned 100 percent of the stock of R&-W since January 1977. Prior to that, another affidavit indicated Williams owned 50 percent.

"We have no problem with R&W. We feel they have satisfied our criteria and we're looking forward to them doing a reasonably large job-that's unusual for a minority firm," said Metro's former director of the office of minority development, Charles A. Dowdy, earlier this year. Dowdy was talking about the subcontract for Ohio Valley.

Metro's office of minority development yesterday estimated that R&W has received approximately $5 million worth of work as a subcontractor on subway projects in the last two years.

"We don't do anything like an FBI or full scale investigation," of firms put forward as minority businesses, said Metro spokesman Cody Pfanstiehl yesterday. "To a certain extent we have to take their affidavits at face value," he said.

When R&W, which also has been known as Rice and Williams Inc., was formed in 1972, all the stock was in the hands of Rice, Williams, Lyon, Campbell and Excavation Construction, according to the indictment. By March 1975, Rice and Williams were the only two shareholders listed.

However, in 1973, Rice and Williams had entered into a shareholders agreement with Excavation Construction that allowed the White-owned firm to select a majority of R&W's board of directors.