Under a PennDOT Public-Private Partnership (P3) contract, Larson Design Group (LDG) and teaming partner Trillium CNG, a member of the Love’s Family of Companies, are providing design and construction phase services for 29 compressed natural gas (CNG) fueling stations and 22 repair garage modifications for transit authorities throughout Pennsylvania. The facilities range in size from 2,000 to 60,000 square feet, with many including parking garages and maintenance building enhancements. CNG fueling stations are different from stations for liquid fuels. Because CNG is a high-pressure gas, sizing, designing, operating and maintaining CNG fueling stations requires specialized knowledge and instruction.

Design services included survey, civil, geotechnical, mechanical, electrical and structural engineering for all fueling station and garages. LDG coordinated all permitting and reviews with appropriate agencies, which was challenging given the multiple authorities/agencies throughout the state. Permit tracking software was developed to assist in organizing and understanding required permits.

For each site, a boundary and topographic survey, including utility locations, was prepared by LDG to establish location of adjacent property lines and physical features of the site within proximity to the areas of improvement. Each site was provided with a new geotechnical report. When needed, flood plain evaluations and wetland staking were also performed.

Geotechnical services included test borings and subsurface exploration, infiltration and laboratory testing, and foundation design recommendations for each site’s fueling canopies and the mat foundations for the CNG storage equipment.

Site design consisted of complete final design, stormwater management, erosion control and land development permitting of the fueling stations. This has resulted in direct interaction with most local county conservation districts and Pennsylvania’s Department of Environmental Protection (PADEP) regional offices, including the Southcentral Regional Office, which will be the permitting entity for Carlisle Barracks.

As an example, under this CNG contract, LDG permitted the Rabbit Transit – Borough of Gettysburg, Adams County project through the Southcentral Regional Office. The project included erosion and sediment control plans (ESCP), stormwater management (SWM) designs and the development of a general NPDES permit submission. ESCP was developed in accordance with Chapter 102 of Title 25 of the Pennsylvania Code with the erosion and sediment control program manual dated March 2012. The SWM design followed local land development ordinances for stormwater controls.

At each location, LDG developed permit and construction documents covering the structural, mechanical and electrical trades with a complex network of more than 20 agencies and authorities utilized by 1,600 transit buses throughout Pennsylvania. The structural design team designed foundations for compressors, station equipment and canopies. The mechanical/electrical design teams prepared station-piping diagrams, electrical distribution to compressors, station equipment, and site lighting.

Progress submittals at the 30-, 60-, 90- and 100% level were prepared for PennDOT and transit stakeholder review. Working with other state and local authorities for land development, highway occupancy, and construction permits, required the design team to develop additional submittal documents at various intervals for each of the 29 separate locations. The design team remained involved during construction, providing construction administration for shop drawing submittal reviews, construction stakeouts, addressing unforeseen conditions, and assisting the contractor with progressive on-site validation of construction progression to assist the design-build team with meeting individual CNG readiness dates. Post construction activities included assisting with the development of the as-built documentation required to complete the construction activities.

Additional services provided by LDG include:

  • 3D Scanning: Many of the transit agencies’ older garage facilities needed to be adapted for installation of CNG-compliant equipment. In some instances, drawings of these existing buildings were not available. LDG’s solution was an innovative application of 3D scanning. Digital models were created from scratch, documenting existing conditions and allowing the design team to more quickly produce construction drawings with a higher level of accuracy than older drawings would have provided.
  • Prototype Designs: CNG compressors typically take up to 14 weeks to build and deliver to a site. Because this program has established standard equipment sizes for compressors and other equipment for all 29 sites in Pennsylvania, Trillium can pre-order equipment which promotes faster delivery and installation, thereby facilitating shortened construction schedules.

CNG components have aided authorities in achieving their sustainable design goals, attaining LEED Silver certification through the U.S. Green Building Council (USGBC). Facility designs have also evaluated including design upgrades such as geothermal heating and cooling and energy-efficient electrical improvements.

In a press release, PennDOT Secretary Leslie Richards said: “We applaud the work of Larson Design Group and Trillium…for advancing Governor Wolf’s efforts to help generate a market for abundant, cleaner burning natural gas.”