EPA TO ADDRESS RAIN'S EFFECT ON ROCKETDYNE; SOME WORRY RADIOACTIVITY WASHES DOWN.

Byline: Douglas Clark Daily News Staff Writer

Predictions of torrential winter rains have scientists and residents asking what impact El Nino could have on the cleanup of radioactive contamination at Rocketdyne's Santa Susana Field Laboratory.

While answers may be as inconclusive as recent weather forecasts, the Environmental Protection Agency will host a public forum next week to offer what information is available.

``There is concern. People have talked about all that, and it was addressed earlier this fall,'' said Tom Kelly, an EPA project manager for the field lab cleanup. ``It's something we need to be conscious of.''

Representatives of the Los Angeles Regional Water Quality Control Board will give an overview of Rocketdyne's surface water discharge permit at 7 p.m. Tuesday at Simi Valley Senior Citizens Center, 3900 Avenida Simi.

Wayne Chiou, associate water resource control engineer, will discuss the water control board's authority and responsibility, and present data revealing where and how much surface water Rocketdyne has discharged over the last year.

``We try to let the public know what is our obligation on the surface water discharge for Rocketdyne,'' Chiou said.

Chiou said Rocketdyne is allowed to discharge 160 million gallons of surface water per day. In the last several months, however, almost nothing has been discharged due to dry weather. In January, only 35 million gallons were discharged throughout the entire month.

``That's way below what they're asking for,'' he said. ``We have no issue there.''

He declined to say what impact El Nino might have on the 290-acre field laboratory, the site of decades of nuclear research.

Joseph Lyou, a scientist who sits on the cleanup oversight committee, said residents who live adjacent to the field lab are concerned that heavy rains could wash contaminants into local waterways.

``It might be a good thing,'' he said. ``It could get the contaminants into the groundwater where it can be cleaned out. But I don't know.''

Geologist James Slosson, of Slosson and Associates in Van Nuys, said that while excessive rains might eventually have a cleansing effect, the short-term danger is that more contaminants could be in the surface water that rushes into streets and the Arroyo Simi.

``More people could be exposed to it at the time it becomes surface water,'' he said. ``Especially kids who like to ride their bikes through it after a storm. That wouldn't be good for them.''

Also, Slosson claims that while Rocketdyne officials have in the past said the rock formations in their hillside location create a ``bath tub'' that obstructs the flow of contaminants into the groundwater, the tub is full of fractures.

``With highly fractured rock, the permeability dramatically increases,'' he said. ``With heavy rains, more mineral contaminants will be flushed out of the rock.''

But Steve Lafflam, Rocketdyne's safety and health director, said El Nino poses no threat because stormwater is diverted into three reservoirs, where it is monitored before it is released through two discharge areas.

Also, in anticipation of storms, Rocketdyne lowers the water level in the reservoirs so that there is no fear of overflow, he said.

``We don't have fears we'll lose hazardous materials off the site,'' he said. ``We only discharge clean water.''

Marilyn C. Underwood, a state Department of Health Services toxicologist who is investigating whether ``exposure pathways'' have allowed radioactive pollution to migrate, agreed that heavy rains may have no effect on contaminants.

``A lot of chemicals are not water soluble,'' she said. ``They stick to soil particles and refuse to move.''

Nonetheless, Kelly said workers have covered certain areas at the cleanup site so that heavy rains will not disturb them. And the cleanup of some areas - like the site of a former building foundation - was finished so that they could be sealed with ground cover before the winter months.

``We decided not to leave any contaminated soil exposed through the winter months,'' he said.