City Hopes to Find Fertile Market for Its Sewage : Environment: A fertilizer made of lawn trimmings and processed sludge will go on sale soon in area gardening stores.

For years, the Japanese Garden at the Tillman water reclamation plant in the Sepulveda Basin has been the testing ground for an unusual city experiment.

But not to worry. The city is not growing mutant trees or genetically altered shrubs. It’s more down-to-earth than that.

The Los Angeles Public Works Department has been lacing the garden’s soil with an organic compost made of lawn trimmings and processed sewage.

And barring any unforeseen hitches, the city will put its byproduct on the market in the next couple of months at gardening shops and home improvement stores under the name Topgro.

City sanitation officials hail it as an idea that combines a spirit of entrepreneurship and a drive to find an environmentally friendly use for 400 tons of sewage sludge produced daily at the Hyperion treatment plant in Playa del Rey. The lawn trimmings used in the mixture come from the city’s curbside recycling program.

“It’s a 100% product of the city of Los Angeles, except for the bag,” said Karen Jones, a sales manager for Organix Supply in Kern County, which has been hired to market the product.

But don’t expect to see the city’s financial picture turn rosy because of the sale of Topgro.

Ray Kearney, a biosolids manager at Hyperion, said the city normally pays a Lost Hills-based company about $30 per ton to haul the sludge from Hyperion to be used as fertilizer for farms as far as Arizona. As part of the agreement with the firm, the city will receive 5% of the gross sales of all products using the city’s sludge--or about 15 cents per ton, he said.

In short, the sale of Topgro will only slightly reduce the cost of hauling the sludge away, Kearney said.

Despite that fact, the city has bigger plans for its sludge. Next year the city plans to open a facility in Griffith Park where manure from the city’s zoo animals will be mixed with lawn trimmings to make a compost that can also be sold for gardening, he said.

The best the city can hope for, Kearney said, is that the sale of such products eventually pays for hauling the sludge away.

The search for new uses of sewage began in earnest in 1987 when city, state and federal regulators came up with a consent decree to improve the Hyperion treatment plant significantly by Dec. 31, 1998, to comply with federal laws on clean water.

Until then, about 100 tons of a day of sludge was pumped through an underwater pipeline extending seven miles offshore, blighting acres of ocean bottom in Santa Monica Bay.

But after the decree, the city stopped discharging the sludge and began recycling in various ways. About half is turned into a powder and burned to help generate power for the plant. The rest has been hauled away for use as agricultural fertilizer.

The Topgro mixture has been used for years in small landscaping projects at the Japanese Garden--a 6 1/2-acre strolling garden adjoining the Donald C. Tillman Water Reclamation Plant.

In the garden, shrubs, azaleas, cherry trees, magnolias, weeping willows, irises and waterlilies thrive in a setting highlighted by stone paths, ponds, waterfalls, bridges and a traditional Japanese-style building and teahouse.

“It works fine,” said Patrick Rigney, a landscape architect at the garden. “It does a good job of conditioning the soil. Here we have heavy clay soil, so anything we have helps.”

But Rigney says the true test for the compost will come in May when nearly 100,000 square feet of Topgro will be used to landscape a levee that is being built to protect the gardens from flooding.

J. P. Ellman, a commissioner on the city’s Board of Public Works, has been using the city compost on her garden and said she already is sold on it. She said the compost meets strict federal standards and can be used on almost any type of flowers, vegetables or trees.

“It’s exciting because it’s using biosolids that were once dumped in the Santa Monica Bay,” she said.