Resources

  • GMA techline

  • Difficult lining task

    April 1, 2010

    This is going to be an extremely difficult job to accomplish with 2mm-thick HDPE liner.

  • Geocell application

    April 1, 2010

    The suitability of geocell as slope surface protection on acidic soil conditions.

  • Optimum height for geotextile storage

    April 1, 2010

    In the waste containment QA/QC technical guidance book by Daniel and Koerner (ASCE Press, 2007, ISBN 0-7844-0859-9), there is a section regarding geotextile storage at a field site.

  • Questions about GM/GCL composite liners

    April 1, 2010

    Three questions and answers about GM/GCL composite liners.

  • Testing HDPE geomembrane liners

    April 1, 2010

    Testing a 30-mil HDPE liner to a pressure between 22-27psi with a maximum pressure drop of 4psi over 3 minutes.

  • Textured HDPE?

    April 1, 2010

    While sand on smooth HDPE is at or slightly higher than 14 degrees, when you have drawdown of the water the hydrostatic forces are sure to bring the sand covering with it.

  • Drainage and filter components for green roofs

    Sponsored by IFAI Expo

    The Purpose of Drainage for Green Roofs

    • Manage rainfall without sustaining damage from erosion/ponding of water
    • Provides void space and slope to transport subsurface water
    • Connects to roof drains, gutters, and scuppers and conducts water away from roof
    • Removes surface water from impervious surfaces
    • Maintains optimum growing conditions in the planting media

    The Purpose of Filter for Green Roofs

    • To prevent fine planting media particles from washing into the drainage layer
    • Prevents the reduction or clogging of drainage capacity
    • Usually a nonwoven geotextile, occasionally a woven fabric, is used

    Filter Components
    For retention:

    • The geotextile must have small enough openings to adequately retain the planting media
    • If not, soil particles will eventually clog the drain core

    For permeability:

    • The geotextile must have large enough openings to allow unimpeded flow of water
    • If not, hydrostatic pressure will build up and the planting media will not drain

    What are Geocomposite Drains?

    • A manufactured material that combines geotextiles and a polymeric core
    • The core composition varies in design and material
    • Geotextiles may be applied to one or both sides using heat bonding or adhesives
    • Geotextiles can filter, protect or hold water
    • Geotextiles are available in sheets or rolls that are overlapped or joined during construction

    Source: “How to Design Green Roofs & Landscapes” presented at the 2009 IFAI Expo, Sept. 22, 2009, in San Diego, hosted by the Geosynthetic Materials Association (GMA)