Oct. 8, 2010: Biology Dept. features Bill Lee speaking on landfill versus compacted clay caps

Friday, Oct. 8, 3:30-4:45 p.m.
CPISB, Room 120

Join the Biology Department and guest speaker Bill Lee on Oct. 8 for a lecture, "Results from a Prospective study of Evapotranspiration Landfill Caps versus Compacted Clay Caps."

The lecture will be about the report of initial results from a prospective comparative study of compacted clay (CCL), versus an evapotranspiration (ET), landfill cap. This study is a pilot scale experiment to determine if an ET cap is equivalent to a CCL cap. The planned study duration is five years. If the final data indicate that the ET cap is equivalent to the CCL cap then an adjacent 50-acre landfill will be closed using an ET cap as an alternative to the prescribed CCL cap. This is the first rigorous comparison of ET and CCL caps conducted in Alaska.

The Biology Department has built two lined in ground lysimeters in Anchorage. Each lysimeter measured 10m x 20m x 2m. The bottom of the lysimeters was constructed with a 2 percent grade and covered with a coarse drainage mesh. Percolate was guided into a sump where it was passed to a rain gauge tipping buckets. The control lysimeter was capped with a CCL cap comprised of three compacted 15 cm thick clay layers and topped with a 15 cm erosion control layer planted with grass. The experimental lysimeter was capped with 65 cm of high organic content soils. Saplings were then planted on the cap. 400 saplings were planted on or around the lysimeter. 144 saplings were planted on the cap. The bottom two-thirds of each lysimeter were filled with a mineral soil.
 
An annual water balance was computed for each cap. The efficacy of the respective cap was computed as the percentage of water blocked by the cap. Initial data indicate that the ET cap's performance will meet or exceed that of the CCL cap. The ET cap was 79 percent effective over the first three years and the CCL cap was 74 percent effective.

UAA parking is free on Fridays. No host refreshments will be provided.

For more information, please contact Sue Farris at ansf3@uaa.alaska.edu.