TREATMENT PLANT TAKES OUT TRASH; FACILITY CLEANS UP TO 10 MILLION GALLONS EACH DAY.

Byline: Kevin F. Sherry Daily News Staff Writer

The way Don Nelson figures it, residents should never need to be concerned with where their water goes after it flows down the drain.

``That means we're doing a good job,'' said Nelson, the city's public works director.

In Thousand Oaks, every drop of water that drains out of sinks, tubs, showers, washing machines or toilets - an average of 10 million gallons a day - reaches the Hill Canyon Waste Water Treatment Plant.

Yet the plant, tucked out of sight in the hills of the city's northwest corner, has been at the center of two battles that only recently ended peaceably.

The first was within the City Council, with the city's elected leaders disagreeing over the extent of improvements needed for the plant and how to pay for the work. Farmers also had to be satisfied with a plan recently approved by state regulators that allows the city to sell treated wastewater from the plant to rural water agencies, and blocking farmers from using that same water that flows in a creek to Mugu Lagoon.

Built in 1960, the plant needs upgrading so it can continue operating safely and keep up with clean-water regulations, Nelson said.

``It's a very necessary part of the city's infrastructure that would have enormous consequences if it would fail,'' he said. ``We need to become current with the technology.''

The battle over plant improvements was led by Councilwoman Elois Zeanah, who voted against the proposed upgrades two years ago. The move sparked a recall effort against Zeanah that ultimately failed in Tuesday's election and followed Zeanah's decision to support a $75 million plant improvement project in September.

The upgrade, expected to take 12 years to complete, will improve antiquated equipment and expand the plant to meet Thousand Oaks' remaining residential growth.

Asked what goes on at this plant, nestled in a peaceful though occasionally odorous corner of Hill Canyon, Nelson said: ``All we do is what nature does naturally. But we just speed it up.''

The Conejo Valley Sanitary Co. built the plant in 1960 and sold it to Thousand Oaks five years later. The plant employs 27 people, who work a range of 10-hour shifts, seven days a week, 365 days a year.

After water flows out of city homes, it's diverted through a series of sewers to the treatment plant. When it arrives, heavy particles drop out of the water, and mechanisms chop up any remaining solids.

In the raw sewage, workers find everything from money to toys to clothing that has found its way into the sewer system. Workers even have discovered false teeth, $100 bills and even diamonds flowing with the wastewater.

Long basins called primary clarifiers then remove solid particles that remain.

A pipe dumps a steady flow of various bacteria and protozoa into the primary clarifiers. As the water churns to mix the organisms and expose them to the air, they munch up to half the waste in the water, said Jack Dudley, the plant's superintendent.

``It's essentially nature's own way,'' said Dudley, who has worked for the city for 30 years. ``We're providing the air, we're providing the bugs.''

In the meantime, plant laboratory workers perform about 10 tests on the water daily to scan for metals, oxygen levels and a variety of potentially harmful substances.

Equipment crams every corner of the tiny building, which was never intended to be a laboratory. Nelson said the plant will soon need a sterile ``clean room'' to comply with ever-stricter water regulations.

``The lab that we have is woefully inadequate,'' he said.

Over in the plant's control room, which was designed as storage space, workers monitor the roughly 10 million gallons of water the plant processes every day.

A paper-and-ink computer strip chart marks the hourly peaks. The needle rises at 7 a.m., when people take showers and baths, and those early morning flows get noticeably higher in the fall.

``We can tell when school gets back in,'' Nelson noted.

After the primary clarifiers, the water flows to secondary clarifiers. These are basically 15-foot-deep, circular pools that allow scum to rise and particles to sink.

``They remove anything that settles, they remove anything that floats,'' Dudley said.

Families of ducks call these pools home.

Next, the water filters through layers of sand and anthracite coal to remove any remaining matter that escaped earlier cleaning processes.

The equipment that controls the filtration process - notably wall lights and panels - looks like something out of a 1950s B movie. The equipment still works, but parts for the decades-old consoles are increasingly difficult to find, Nelson said.

``We have to go to salvage operations,'' he said. ``This whole room could be replaced by a tiny computer.''

After filtration, chlorine is added to kill any remaining organisms before sulphur dioxide removes the chlorine.

The treated wastewater then simply dumps into Conejo Creek, which merges with Calleguas Creek on the Oxnard Plain at the base of the Santa Monica Mountains and winds up in Mugu Lagoon.

By the time the water is discharged from the plant, it is indistinguishable from any bottled water, though unsuitable for drinking, Nelson said.

On Sept. 18, the State Water Resources Control Board approved the city's plan to resell the treated wastewater, ending a decades-long battle with water agencies and area farmers.

The plan allows Thousand Oaks to use the water for urban landscaping and sell it to the Camrosa and Pleasant Valley county water district. Their customers would include farmers who have pumped the creek but should gain a more convenient and dependable supply from the agencies.

The first reclaimed water sales are expected in 1999, reducing use of imported drinking water and groundwater pumping that threatens an aquifer with seawater intrusion.

``The intent of that is to preserve agriculture in the community,'' Nelson said. ``It just takes pressure off other supplies.''

CAPTION(S):

2 Photos

Photo: (1) Public Works Director Don Nelson, left, and plant superintendent Jack Dudley check the primary clarifier.

(2--Ran only in Conejo edition) A mallard takes flight from the Hill Canyon treatment plant's secondary clarifier, where wastewater is partially cleaned via gravity.

Tina Gerson/Daily News