The Roaring Fork Transportation Authority (RFTA) recently decided to convert 22% of its fleet of buses to Compressed Natural Gas (CNG).
In order to enable CNG fueling to take place within the existing facility, significant modifications were required to existing mechanical systems, electrical systems and controls. The advanced methane and carbon monoxide detection system has a number of safeguards built into it to activate upon predetermined percentages of the lower explosive limit of methane gas, such as opening overhead doors, turning off certain electrical systems and turning on exhaust fans and air supply units.
Additionally, RFTA has taken the unique approach of allowing indoor fueling with CNG. In order to accomplish this, the existing fuel bay has been upgraded to entirely Class I / Division II electrical, mechanical and significant structural reinforcing.
The intent of the structural upgrade is to protect the existing structure in the event of a deflagration and includes deflagration vents on one wall of the existing fuel bay to allow pressure to dissipate to the exterior. The demarcation line between the fuel bay and existing structure will include a 14’ x 14’ vertical lift blast door rated to withstand 200psf of blast pressure. In conjunction with this project MWGC is constructing a CNG Fueling Station featuring approximately 1,600-sq-ft of masonry/structural steel on a 3’ thick mat foundation that will house the natural gas compressors, dryers and storage vessels. This will allow RFTA to fuel both inside and outside of the existing Glenwood Maintenance Facility.
The work includes earthwork, utilities, running of CNG lines to the existing GMF, standing seam metal roofing, overhead coiling doors, extensive stainless steel piping, and a new emergency backup generator capable of operating the entire facility. A 4” high pressure natural gas line will be installed to provide the three 200 HP CNG compressors with supply to support 24/7 fueling operations at two fuel dispensers with capacity to add two additional dispensers in the near future.