Officials Nosing Around for Solution to Sewage Plant Expansion Problems

In response to North County’s skyrocketing population, the Encina Water Pollution Control Facility has embarked on an ambitious $48-million expansion that will nearly double the sewage plant’s capacity.

The drawback, however, is that more sewage means more smell and more of that tough-to-get-rid-of sludge--both problems that Encina officials will be pressured to solve over the next few years.

Bidding Closed Last Week

While the expansion project has been in the planning stages for three years, bidding closed just last week for the actual construction of two additional aeration basins (where condensed sewage is set out to dry) plus other improvements. The expansion is scheduled to be finished in early 1992 and should meet the needs of Encinitas, Leucadia, Carlsbad, Vista and San Marcos through 2005, when the area will have a projected population of 355,000, according to plant general manager Rick Graff.

Those plans include a permanent solution to the pervasive stench that now makes back-yard barbecuing and other outdoor activities a horror for nearby residents, especially those in the pricey condominiums to the east of Interstate 5 and downwind from the coastal plant.

Permanent covers made of fiberglass or other material capable of withstanding the deleterious effects of constant moisture are planned for the two existing aeration basins and the two yet to be built. The covers, plus high-tech scrubbing and filtering equipment costing $4.3 million, should effectively squelch the odor problem, Graff said.

But what to do until then? Three years is a long time to wait when the ocean breeze wafting past your home carries the distinct odor of an overflowing toilet.

The Encina Joint Advisory Committee, composed of members of the six North County agencies that are served by the plant, has scheduled a special meeting Wednesday to grapple with the odor problem.

One alternative bandied about at last month’s committee meeting is to temporarily reduce the plant’s treatment level from secondary to advanced primary. The plant began using secondary treatment last October, after years of pressure from local environmental groups concerned about the quality of the effluent being dumped offshore. But the upgrade in treatment was accompanied almost immediately by an increasingly foul odor.

‘Doubled the Amount of Flow’

Secondary treatment, unlike advanced primary, means the sewage must be allowed to settle for a while in the open aeration basins while it undergoes biological treatment to remove bacteria, viruses and toxins.

“It has doubled the amount of flow now being treated in the aeration basins, and the consultants are telling us that’s where the odor is coming from,” said Carlsbad City Engineer Lloyd B. Hubbs.

The sewage plant is permitted to reduce the level of treatment because of a waiver from the Environmental Protection Agency and the Regional Water Quality Control Board, which exempts them from having to operate at the secondary treatment level until the end of the year, Graff said. In December or January, however, the plant would be required to resume secondary treatment.

Any attempt to reduce the treatment level, even temporarily, is certain to meet strong resistance from local environmental groups, who have plans to raise a stink of their own. Carlsbad attorney Richard MacManus, founder of People for a Clean Ocean, said Monday: “We’re going to fight them on it. If they do (reduce the treatment level), we’ll walk the beaches and hand out fliers telling people about the quality of the water they’re swimming in.

“You don’t jeopardize the public health because of a temporary odor issue affecting a small number of residents.”

Graff, the general manager, said in an interview Monday that he will recommend at Wednesday’s meeting that the treatment level be kept at secondary, despite the smell. Going back to advanced primary treatment “doesn’t appear to have any advantage,” said Graff, given the short amount of time before the process would have to be reversed. “Switching back and forth would only create more odors, since it is an ongoing biological process,” he said.

Graff said his staff report suggests other immediate actions to mitigate the smell, such as putting temporary covers over the aeration basins and channels. Workers at the facility have put makeshift plywood covers over about 16% of the 3,360 square-foot open surface within the last two weeks, he said.

While Encina officials struggle to control the unappetizing smell in time to salvage some of the summer picnic season, the sludge matter is pending.

Nearing Capacity

The Otay Mesa landfill is the only dump in San Diego County that will accept sludge--the stuff that is left over after the moisture has been squeezed out of the sewage--and it is quickly nearing its capacity.

One year ago, Encina contracted with a soil-supplement firm called Pima-Grow to haul unwanted sludge to Arizona for agricultural uses.

But the Pima-Grow contract expires in 1993, and the Otay landfill may be full before then. In anticipation, the Encina Joint Action Committee is searching for a suitable locale within its jurisdiction to establish a composting site, where the sewage can be processed into fertilizer.

“Reuse and recycling is the best way to go,” Graff noted. “It’s very, very good material for soil buildup.”

Graff said the Encina staff plans to come up with a list of potential composting sites in time for the committee’s August meeting.

Then will the scrambling to keep up with the prolific sewage output of the booming North County population cease? Not likely.

“If we complete this job in 1992, I imagine by 1995 we’ll be planning our next expansion, trying to maintain our ability to serve the area,” Graff said.