- Aka Energy Group, LLC
- Anadarko Petroleum Corp.
- Atlas Energy, L.P.
- Burnett Oil Co., Inc.
- Cabot Oil & Gas Corp.
- Carrizo Oil & Gas, Inc.
- Chesapeake Energy Corp.
- Chevron Corp.
- Chief Oil and Gas
- CONSOL Energy
- DTE Pipeline Company
- Energy Corporation of America
- Enerplus Resources USA
- EOG Resources, Inc.
- EQT Corp.
- EXCO Resources (PA), LLC
- Hess Corp.
- Hilcorp Energy Company
- Hunt Marcellus Operating Company, LLC
- Inflection Energy, LLC
- MarkWest Liberty Midstream & Resources, LLC
- Newfield Exploration Company
- NiSource Gas Transmission & Storage
- Noble Energy, Inc.
- Penn Virginia Oil & Gas Corp.
- Pennsylvania General Energy
- Peoples Natural Gas
- PDC Mountaineer, LLC
- PVR Marcellus Gas Gathering
- Range Resources Corp.
- Rex Energy Corp.
- Seneca Resources Corp.
- Shell Appalachia
- Southwestern Energy Company
- Statoil
- Talisman Energy USA, Inc.
- Triana Energy USA, Inc.
- UGI Energy Services
- Ultra Resources
- Williams Companies
- WPX Energy
- XTO Energy Inc.
- Acorn Energy
- Accutest Laboratories
- Advanced GeoServices Corp.
- AECOM
- Aerotek
- AES Drilling Fluids LLC
- Allan A. Myers, Inc.
- ALS Environmental
- Altela Inc.
- AMEC
- Amerimar Realty Company
- Appalachian Oil Purchasers, Inc.
- Aqua America, Inc.
- Aquatech
- ARCADIS-US, Inc.
- ARM Group Inc.
- AVT, Inc.
- Babst, Calland, Clements & Zomnir
- Baker Hughes
- Barrett Industries (IA Construction)
- Benchmark Analytics, Inc.
- Benesch
- Bergmann Associates
- Bishop Brothers Construction
- Blackhawk Specialty Tools
- BL Companies
- Blank Rome LLP
- Boots & Coots
- Borton-Lawson
- Bravo Group
- Bruce & Merrilees Electric Company
- Buchanan, Ingersoll & Rooney, PC
- Buchart Horn, Inc.
- Burleson LLP
- Capstone Turbine Distributor/E-Finity
- Casella Waste Services
- CDM Smith
- Cemex
- CESI Chemical, a Flotek Company
- CHA
- Chapman Corporation
- Chester Engineers
- Civil & Environmental Consultants, Inc.
- Clean Energy Fuels Corp.
- Clean Harbors
- Cleveland Brothers Equipment Co.
- CMS Energy
- Conestoga-Rovers & Associates
- Contract Land Staff (CLS)
- Cozen O’Connor
- Crescent Directional Drilling, LP
- Crowell & Moring LLP
- CSD Engineers, LLC
- CUDD Energy Services
- Cummings/Riter Consultants Inc.
- Dawood Engineering, Inc.
- Dawson & Associates
- Dechert
- Dell Fastener Corporation
- Deloitte Consulting LLP
- Dewberry
- DLA Piper
- Drill Baby Drill Staffing
- Duncan Land Services
- Duquesne Light Holdings, Inc.
- Eckert Seamans Cherin & Mellott, LLC
- Edgen Murray
- Emera Energy
- Entech Engineering, Inc.
- Environmental Drilling Solutions
- Environmental Resources Management, Inc.
- Environmental Service Laboratories
- Environmental Standards, Inc.
- Eureka Resources, LLC.
- Express Energy Services
- Exterran
- Falcon Drilling
- Fisher Associates
- FMC Corporation
- Force Incorporated
- Fox Rothschild
- FTS International
- Fulbright & Jaworski
- G4S Secure Solutions USA
- G.A & F.C. Wagman, Inc.
- GAI Consultants, Inc.
- Gannett Fleming, Inc.
- Gas Technology Institute
- Geosyntec
- Gilmore & Associates
- Glenn O. Hawbaker, Inc.
- Golder Associates, Inc.
- Green Field Energy Services
- Greenberg Traurig, LLP
- Greenhorne & O’Mara, Inc.
- Groundwater & Environmental Services
- Hallaton, Inc.
- Halliburton Energy Services
- Hartman & Hartman
- Hatch Mott MacDonald
- HDR Engineering, Inc.
- Henkels & McCoy
- Herbert, Rowland & Grubic, Inc.
- Herschell Environmental LLC
- High Industries/High Real Estate Group
- Hoffman Construction Services
- Holcim
- Holloman
- Homewaters Retreats
- Honeywell Safety Products
- HRI, Inc.
- Hull & Associates, Inc.
- Independence Excavating
- INTERTECH Security
- IPS Engineering/EPC
- Jackson Kelly, PLLC
- JMC Steel Group
- JMT Johnson, Mirmiran & Thompson
- John T. Boyd Company
- K&L Gates
- Keane Frac
- Key Energy Services, Inc.
- Kleinfelder
- KPMG
- Kroff Well Services, Inc.
- LJ Stein & Company, Inc.
- L.R. Kimball & Associates, Inc.
- Lafarge North America
- Lancaster Laboratories
- Langan Engineering and Environmental Services
- Lanxess
- Larson Design Group/TerrAqua Resource Management
- Laurel Aggregates
- Lowe’s Home Improvement
- M. Davis & Sons Inc.
- Manko, Gold, Katcher & Fox, LLP
- Mascaro Construction Company, LP
- MATCOR Inc.
- McCarl’s
- McClure Company
- McGuireWoods, LLP
- McKissack & McKissack
- McNees, Wallace & Nurick, LLC
- McTish, Kunkel & Associates
- Michael Baker Corporation
- ModSpace
- Moody and Associates, Inc.
- MSA
- MWH
- Nalco Company
- National Oilwell Varco (NOV)
- National Vacuum Corp.
- Nemacolin Woodlands Resort./84 Lumber
- New Enterprise Stone Lime Co. Inc.
- New Pig Corporation
- New Tech Engineering
- O’Brien & Gere
- Ogletree, Deakins, Nash, Smoak & Stewart
- Orion Drilling
- Oxford Development Company
- Pace Analytical Services, Inc.
- ParenteBeard, LLC
- PB Energy Storage Services, Inc.
- Penn E&R
- Pennoni Associates, Inc.
- Pennsy Supply, Inc.
- Pennsylvania American Water
- Penn United Technologies
- Pepper Hamilton, LLP
- Percheron Acquisitions, LLC
- PGT Trucking
- PJ Dick-Trumbull Corporation
- P. Joseph Lehman, Inc., Consulting Engineers
- PPG
- PwC (PricewaterhouseCoopers)
- Protechnics (A division of Core Laboratories)
- Prudential Preferred Realty
- Purestream Technology
- Quanta Pipeline Services/QPS Engineering, LLC
- ReedSmith, LLP
- Reserved Environmental Services, LLC
- RETTEW
- Ridge Global
- River Chemical and Energy, a River Development Corporation
- RPM Industries LLC
- RT Environmental Services
- Russell Standard Corporation
- SAIC (Science Applications International Coporation)
- Saul Ewing
- Saxon Drilling
- Schlumberger Oilfield Services
- Schneider Downs & Co., Inc.
- Schramm
- Sci-tek Consultants Inc.
- Select Energy Services, LLC
- Sevenson Environmental Services
- SGC Engineering, LLC (Member of The Senergy Group)
- Shallenberger Construction, Inc.
- Skelly and Loy, Inc.
- SSM Groups
- Stahl Sheaffer Engineering, LLC
- Stallion Oilfield Services
- Stantec Consulting Corporation
- Steptoe & Johnson
- STRAD Oilfield Services
- STV Energy Services, Inc.
- Suit-Kote Corporation
- Sunnyside Supply, Inc.
- Superior Energy Services, Inc.
- Superior Well Services, Ltd.
- Sustainable Resources Group
- SWCA Environmental Consultants
- T & M Associates
- Taylor Wiseman & Taylor
- Tensar International Corporation, Inc.
- TerrAqua Resource Management (TARM)
- Terra Services LLC
- TestAmerica Laboratories, Inc.
- Tetra Tech
- The EADS Group
- The Gateway Engineers
- The Lane Construction Corporation
- The Linde Group
- The Sadler Law Firm
- The Shaw Group
- The West Firm
- THP Gas Field Services
- TMK IPSCO
- Total Equipment Company
- Total Safety U.S., Inc.
- TRC
- Trinity Consultants, Inc.
- Twilight Services
- United States Steel Corporation
- UniversalPegasus International
- Urban Engineers
- Universal Well Services, Inc.
- URS Corproration
- USA Compression
- Valerus
- Vallourec & Mannesmann USA
- Veolia Environment North America
- Wallace & Pancher, Inc. (WPI)
- Waste Management
- Weatherford International Ltd.
- Weavertown Environmental Group
- Weston Solutions, Inc.
- West Penn Energy Services, LLC
- Willbros Engineering
- Williams Scotsman
- Wilkinson & Associates
- Womble Carlyle Ecology Innovations
- Womble Carlyle Sandridge & Rice
- WorleyParsons
- WSP Environment & Energy
