Washington Suburban Sanitary Commission electricians knew that batteries used to power emergency systems in the main water treatment plant "had not been performing satisfactorily" at the time fire severly damaged the plant earlier this month, the WSSC general manager said yesterday.

Nevertheless the WSSC workers continued to use the specially-designed batteries - supplemented by truck batteries - to power the failsafe systems for the four months prior to the fire, according to Robert S. McGarry, the general manager.

The failsafe systems, designed to shutdown the plant's operation at the first hint of a fire or other problem, failed to operate correctly when fire first started on the morning of July 6. The fire spread extensively throughout the pumping station as a result, triggering a five-day water crisis in suburban Maryland, McGarry said.

McGarry, who said he did not know that batteries were being used before the July 6 fire, said that "those responsible for the technical command" at the WSSC decided to use a makeshift system because the WSSC was awaiting the arrival of a new battery charger and set of replacement nickle-cadmium batteries.

In addition, McGarry said the batteries at the plant before the fire were specially made for the WSSC's Potomac River Water Filtration plant on River Road and are no longer manufactured.

McGarry said yesterday that the fire started with a short circuit in the starting coil of a water pump. The short, he said, caused a drain on the batteries that shut off power to the plant when there is an emergency. If the breakers had been working, the fire would not have spread so rapidly, causing a total breakdown at the plant, he said.

The short in the starting pump occurred, McGarry aid, when a plant operator attempted to turn on an additional water pump at about 6:40 a.m. July 6 in order to meet the high demand for water that occurs in the morning.

The Potomac plant serves 1.2 million residents in suburban Maryland and, before the breakdown two weeks ago, was pumping an average of 170 million gallons of water a day into the bi-country water system.

When asked if such an incident could happen again, McGary smiled and said. "This is a fairly standard DC-powered (failsafe) system." Later he said that "if he had (another) short as severe as this," the system could again fail to function.

He said he intended to bring on board the very finest consultants that we can get out hands on fast" to make recommendations on how to improve the existing failsafe system.

The fire, resulted in about $500,000 in damage to WSSC equipment, but the loss will probably be covered by the commission's insurance, according to McGarry.

McGarry stressed at a press conference yesterday that the plant operator who turned on the additional pump did so only after checking if DC voltage was adequate. The voltage in the batteries read 103 before the additional pump was started. Although the voltage should be at 135 when the batteries are operating perfectly. McGarry said voltage could go as low as 90 and a pump would still be able to start.