Invited Session: Closing Dumpsites
Sustainable ET Landfill Covers: A Savannah Based Ecosystem Design (0.5 CEU)
Monday, September 25, 2017
15:30 – 16:00
Moderator: Tracie Onstad-Bills, Northern California Director SMM, SCS Engineers, California
In 2005, the Hamm Sanitary Landfill concluded that maintaining a “lawn” of cool season grasses across 360 acres during a 30-year closure period would be very costly and time consuming to maintain with mowing, fertilizing and occasional irrigation needed. Based on this concern and the structural and maintenance concerns associated with a standard U.S. Environmental Protection Agency Subtitle D “composite” cover, an idea was spawned whereupon a less maintenance-intensive native prairie grass and tree islands sustainable cover design would be pursued. A sustainable low maintenance cap providing a refuge for wildlife habitat was a project goal. You can’t fight Mother Nature. Native vegetation will take over a closed landfill without extensive maintenance and upkeep. Why not plant what will end up on the cap from the beginning?
Participants will learn how to determine where alternative evapotranspiration (ET) caps are appropriate. A comparison of alternative caps vs prescriptive caps will be presented. We will examine cap thickness determination methods and compare seed bed soil selection criteria. We will evaluate which to plant first: grasses or trees and shrubs. We will discuss envisioning and designing the end result the landfill owner desires. A more natural looking landscape was the project’s goal.