Post- Waste Management

Yesterday’s landfills are becoming tomorrow’s parks, golf courses and even housing sites. The now- defunct Lopez Canyon Landfill above Lake View Terrace is the latest garabe dump to undergo such a metamorphosis.

The last- city owned dump, Lopez accepted its final load of garbage in July and is now in a five- year closure process that will cost about $ 18 million. During its 21 years in operation, Lopez took in 16.5 million tons of trash, enough to fill the 392- acre dump to a depth of about 1,740 feet.

After it is sealed off and planted over with native vegetation, the Lopez site will become a “passive recreation” park. It will be fenced off and used only for educational tours. The methane gas produced by the decomposing trash will be converted to electricity at an on- site pwoer plant to be built within the next two years. During the course of the closure, ground water wil be monitored for contamination.

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The procedure for closure of landfills varies according to the dump’s size and location, but there are steps basic to any closure. A low- permeable layer of clay seals in decomposition fumes and prevents surface water from filtering down to the trash below and contaminating the ground beneath. Depicted at right is a typical closure process:

A: Foundation layer of soil is placed.

B: Surface is tilled and compacted.

C: Clay sealant layer is applied.

D: Vegetation is planted.

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(from bottom up)

* Two feet of clay material

* .08 inch of high- density polyurethane

* Pipe system to collect drainage of “leachate”

* Dirt layer

* Trash

* Soil foundation layer (minimum 2 feet)

* Clay sealant layer (minimum 1 foot

* Vegetation layer

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Currently, methane gas in vaccumed through horizontal and vertical perforated pipes in the landfill to a flare that burns off the gas. Once the power plant is operational, it is expected to generate between 10 asnd 12 megawatts of electricity, enough to power 10,000 homes, per month. Officials expect the trash to produce energy for about 30 years.

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There are no state regulations on what can or can’t be built on a landfill. There are, however, rules regulating how a structure is to be built. How soon development can begin after a landfill’s closure varies. Generally, more settling time is required for structure than for parks or other facilities. Some possible post- dump uses:

* Golf courses.

* Office buildings, Retail stores, Residential structures.

* Parks

Sources: Los Angeles Bureau of Sanitation; California Waste Management Board; staff reports; Researched by JULIE SHEER / Los Angeles Times