Today, Jeffrey Ludlow, Vice President and Intern Shant’e
Austin of Treadwell & Rollo, a Langan Company, visited to give a
presentation to CCSF students about the work they performed to ensure that the
EcoCenter would be safe and strong.
Treadwell and Rollo’s research of the site led the company to recommend
that a shallow mat foundation would be the most cost-effective and efficient
solution. The alternative was the more
expensive pile foundation that is most often used for buildings on closed
landfill sites. The pile foundation was also not a good alternative as its construction would puncture the geosynthetic clay liner several feet under the building. The liner serves as a cap to prevent stormwater infiltration into the fill that created Heron's Head Park. Water seepage could cause unsafe leachate that could make its way into the surrounding soil and water.
Mr. Ludlow also discussed the company’s design of a methane
mitigation system that was installed by KLM Builders to minimize the
possibility of this common landfill gas from migrating into the building. The system is located beneath the concrete
slab foundation and is composed of a methane-impermeable membrane. Beneath the membrane is a layer of crushed
rock that contains a network of horizontal perforated pipes that lead to
vertical risers that vent to the roof.
The system allows any methane gas to be trapped and move through the
rocks and pipe to the building’s rooftop exterior. For over a year, former LEJ youth intern
Shant’e Austin under the supervision of Jeffrey Ludlow has come to the
EcoCenter to measure methane levels in the building and on the rooftop. Ms. Austin showed students the meter used to
measure both methane and oxygen levels and how it is calibrated before each
use. The methane levels have been
non-detectable and the public health requirement for monitoring will sunset
April 2013. All in attendance were very
grateful for this very informative and interesting talk that helped deepen understanding
of the building of the EcoCenter and important maintenance and monitoring requirements.
