The Environmental Protection Agency said yesterday it found "apparent substantial cost overruns and delays" in a limited review of construction projects at the Blue Plains sewage treatment plant, and announced it would conduct an in-depth audit of the regional facility.

The federal agency asked the D.C. government, which runs the plant at the southern tip of the District, to respond to the allegations. But the EPA blacked out the city's comments when the audit was released to reporters because D.C. officials said they did not want their answers made public.

The inspector general's office of the EPA began its review at the request of William K. Reilly, the agency's administrator, after The Washington Times published articles last fall asserting that 14 recent Blue Plains construction projects rose 28 percent over budget and ran an average of 14 months behind schedule.

The newspaper questioned the District's management and contracting practices, saying more than 70 percent of the cost increases were caused by design problems, changes and contract delays.

The 14 projects in question included construction of a new central maintenance building; a facility to prevent sewage from overflowing into the Anacostia River during storms; and chlorination, dechlorination and grit-removal facilities, as well as renovation of a pumping station. The projects were undertaken from 1985 through 1989.

The sewage plant treats waste for 2 million people from the city and Maryland and Virginia suburbs, with the District and suburban governments sharing operating costs. The EPA pays for up to 85 percent of construction costs.

The EPA's lawyer is reviewing the District government's reasons for wanting its comments kept secret. Officials in the EPA's inspector general's office hope for an answer "within a week or so," said John Walsh, chief of the office's financial audit unit.

Tara Hamilton, a spokeswoman for the Public Works Department that runs the plant, said officials wanted their comments kept confidential because they were a "preliminary, internal analysis of a series of articles in the newspaper," not a formal reply to federal allegations. She said District officials disagree with "some aspects of the articles."

The EPA finding of cost overruns and delays is the latest in several recent questions raised about Blue Plains's operations and management. Fairfax County Executive J. Hamilton Lambert said the suburban jurisdictions that use Blue Plains have raised questions similar to EPA's about the plant's construction project management.

The U.S. Justice Department, while saying the plant generally was well-run, took the city to federal court last year for allegedly violating a 1985 consent decree promising to make improvements at Blue Plains.

The District auditor's office is studying the plant's sludge-hauling contracts.

The Washington Suburban Sanitary Commission, which represents suburban Maryland governments, will add an audit of construction spending to its annual review of Blue Plains's operating expenses over the next several months.

The EPA is disputing the plant's plans to burn sludge, the final product of sewage, claiming it should be spread on farmland instead. The plant has been without a permanent administrator for nearly a year, when Wallace White resigned.

The EPA report said its limited review "could not determine the exact amount of the construction and consultant cost overruns, or the exact length of time delays that occurred. Further, we could not determine the cause of these cost overruns and time delays."

The EPA also did not rule on the eligibility for federal money for the construction of an auxiliary ballfield for visiting teams at Robert F. Kennedy Stadium, a project questioned by the newspaper's series.