Pouring Before It Rains : Flood control: An army of workers are building new concrete walls along a stretch of the Santa Ana River, making it wider, deeper and safer to handle flooding.

Like swarms of mechanical ants, busy lines of trucks, tractors and cement mixers now cover the bottom of the dry Santa Ana River bed between this city and Costa Mesa.

Huge mounds of brown alluvial dirt are being excavated and relocated. Massive walls of concrete are going up, replacing older, shallower slopes.

The river channel is being made wider, deeper and safer. For although the Santa Ana River seems like an illusion most of the year, in rainy months it is a potential mauler and killer. The Army Corps of Engineers lists the Santa Ana as the biggest potential flood threat in the West.

“This river has had several major floods in the past,” said Ed Andrews, 41, the Corps of Engineers’ project manager for the work now going on in the lower Santa Ana River. “A flood of this river could put a big portion of Orange County under water. It could cause $15 billion in damage.”

The Corps’ work at the mouth of the Santa Ana River first began in the fall of 1990, with work on the marshes and estuary.

The widening and dredging of the river bed in the Huntington Beach, Newport Beach and Costa Mesa areas began last year. Now the riverbed work has extended north as far as Fountain Valley. Drivers crossing bridges in the area can view a maze of construction work in the river bed for as far south as the eye can see.

The work is part of an overall $1.4-billion project by federal and local governments. Completion is expected by the year 2000 for the overall project, which includes work on the river in central and north Orange County and in Riverside and San Bernardino counties.

But the lower Santa Ana River work will be finished by fall of next year. The Corps of Engineers launched the massive river-taming project at the mouth of the river. Thus, that section will be the first to be completed.

“We started at the ocean because that part of the river has to be able to handle all the drainage from upstream,” Andrews said. He also noted that the mouth of the river, between Huntington Beach and Newport Beach, posed some environmental problems that had to be addressed before other work could proceed.

“We’ve already restored some marshes here near the ocean,” said Andrews. “And we’ve worked to protect endangered species in the area, including the least tern.”

The Santa Ana River, in centuries past, has been somewhat of a gypsy. The river changed its course from time to time--a matter of small consequence when this area was sparsely populated.

Today, however, expensive homes and businesses bump up to the channel that now contains the Santa Ana River. Devastation would result if the river again sought a new course to the sea.

Andrews said that massive residential development on both sides of the Santa Ana River makes it impossible to widen the river channel in many locations. In those places, the civilian contractor hired by the Corps is building 20-foot-tall concrete walls on both sides of the river. These walls will replace the sloping pavement of the old riverbed. The riverbed, in these narrow areas, will also be paved with concrete.

“It’s like a concrete box,” Andrew said. He added that the flow of the river will be smoother and faster because of the new vertical walls and concrete river bottom.

Workers on the bottom of the riverbed say they find the project challenging and exciting.

“I live in Santa Ana, near the river, and so I like working here” in the riverbed, said Fernando Orozco, 40, one of the Corps of Engineers’ inspectors on the project. “I like the cool breezes that come during the day.” Those ocean breezes blowing up the riverbed, unhindered by buildings, provide a form of natural air conditioning, he said.

Wayne Grantham, 48, of San Diego, a technician with the Corps, was in the riverbed Tuesday, testing the quality of concrete being poured into massive forms. “We test periodically to see that concrete is up to standards,” he said.

Grantham said he has worked in a “lot worse places. As for the weather, it gets a little hot about 9 or 10 in the morning, but then that ocean breeze comes up and it cools things off.”

Bill Gallegos, 41, of Pomona, the Corps’ resident engineer for the project, said he was “proud to be working on this. It’s a part of history--the history of Orange County. We’re building something here that is really historic.”

Taming a River How a portion of the Santa Ana River bed is being widened and dredged to help prevent flooding. Riverbed: to be expanded from 250 feet wide to maximum of 365 feet. Riverbed: was 15 feet deep; will be 22 to 25 feet Wall height: 12 to 15 feet above ground Auxilliary channel: 60 feet wide Walls: steel-reinforced concrete walls Expected completion for this portion: late 1993 Result: capacity will more than double from 22,000 cubic feet per second to 47,000 Dirt removal: 1.9 million cubic yards of dirt, rocks, sand and concrete. It will be recycled for use in local road and freeway projects. Source: Army Corps of Engineers