National Permanent Federal Savings and Loan Association, the District's second-largest thrift, yesterday announced plans to absorb Eastern Liberty Federal Savings and Loan Association.

The merger will put National Permanent neck-and-neck for second place with Columbia Federal and First Federal which filed an application to merge in August. Perpetual, which announced last May it would merge with American Federal, is the largest.

National Permanent currently has assets of $715 million and reserves of $46 million. The merger with Eastern Liberty will bring its assets to $929 million and reserves to $55 million.

Both institutions are said to have been looking for partners for some time. Eastern Liberty incurred a $451,000 operating loss in 1979 and a $1.3 million loss during the first six months of 1980. Its reserves dropped from $10.7 million in December 1979 to $9.4 million in June.

John W. Stadtler, chairman of National Permanent, will retain the position in the merged S&Ls. Thomas R. Harrison, president of Eastern Liberty, will become a vice chairman of National Permanent. Stadtler said some duplicate offices will be closed and the combined number brought down to 19. He said he hopes to accommodate all of Eastern Liberty's staff.

At the beginning of this year there were 16 savings and loans in the District. If all the planned mergers are approved, the number will be reduced to 11. In addition to the three already mentioned, Capital City and Northwestern have announced a merger, as have Interstate and Metropolis.