- Accutest Laboratories
- Advanced Disposal
- Advanced GeoServices, Corp.
- Advantage Resource Group
- AECOM
- Aerotek
- AES Drilling Fluids LLC
- Allan A. Myers, Inc.
- Allegheny Pipe & Supply Company
- ALS Environmental
- Altela Inc.
- AMEC
- Anchor Drilling Fluids USA, Inc
- Apex Companies, LLC.
- Aqua America, Inc.
- Aquatech
- ARCADIS-US, Inc.
- ARM Group
- AVT, Inc.
- Babst Calland Clements & Zomnir
- Baker Hughes
- Barrett Industries (IA Construction)
- Benchmark Analytics
- Benesch
- Bergmann Associates
- Bishop Brothers Construction
- BJ Inspections, Inc.
- Borton-Lawson
- Bowman Consulting
- Bravo Group
- Bruce & Merrilees Electric Company
- Buchanan, Ingersoll & Rooney, PC
- Burleson LLP
- Casella Waste Services
- CB&I
- CDM Smith
- Cemex
- CESI Chemical, a Flotek Company
- CHA
- Chapman Corporation
- Chester Engineers
- Civil & Environmental Consultants, Inc.
- Cleopatra Resources
- Cleveland Brothers Equipment Co.
- CMS Energy
- Conestoga-Rovers & Associates
- Cozen O’Connor
- Crescent Directional Drilling, LP
- Crowell & Moring LLP
- CRS Reprocessing Services
- CSD Engineers, LLC
- CUDD Energy Services
- Cummings/Riter Consultants, Inc.
- D.A. Nolt, Inc.
- Dawood Engineering, Inc.
- Dawson & Associates
- Dechert
- Deloitte Consulting LLP
- Dewberry
- DLA Piper
- Draeger Safety, Inc.
- Duquesne Light Holdings, Inc.
- Eckert Seamans Cherin & Mellott, LLC
- EHS Support, Inc
- EnergySolutions
- Entech Engineering, Inc.
- Environmental Drilling Solutions
- Environmental Service Laboratories
- Environmental Standards, Inc.
- ERM
- Ernst & Young
- Eureka Resources, LLC.
- Eurofins Lancaster Laboratories
- Express Energy Services
- Exterran
- Falcon Drilling
- Fisher Associates
- Five Corners Strategies
- FMC Corporation
- Force Incorporated
- Fox Rothschild
- FTS International
- Fulbright & Jaworski
- G4S Secure Solutions USA
- G.A. & F.C. Wagman, Inc.
- GAI Consultants, Inc.
- Gas Technology Institute
- Geosyntec
- Gilmore & Associates
- Glenn O. Hawbaker, Inc.
- Golder Associates, Inc.
- Graycor Industrial Constructors, Inc.
- Green Field Energy Services
- Greenberg Traurig, LLP
- Groundwater & Environmental Services
- Hallaton, Inc
- Halliburton Energy Services
- Hartman & Hartman
- Hatch Mott MacDonald
- HDR Engineering, Inc.
- Heckmann Corporation
- Henkels & McCoy
- Herbert, Rowland & Grubic, Inc.
- High Industries/High Real Estate Group
- Hoffman Construction Services
- Holloman
- Homewaters Retreats
- Honeywell Safety Products
- HRI, Inc.
- Hull & Associates, Inc.
- INTERTECH Security
- IPS Engineering/EPC
- Jackson Kelly, PLLC
- JMC Steel Group
- JMT Johnson, Mirmiran & Thompson
- John T. Boyd Company
- K&L Gates
- Keane Group
- Kelchner, Inc.
- Kleinfelder
- KPMG
- LJ Stein & Company, Inc.
- Lafarge North America
- Lancaster Laboratories
- Langan Engineering and Environmental Services
- Lanxess
- Larson Design Group
- Laurel Aggregates
- LJ Stein & Company
- M. Davis & Sons Inc.
- Magnetrol International, Incorporated
- Manko, Gold, Katcher & Fox, LLP
- Mascaro Construction Company, LP
- MATCOR Inc.
- McCarl’s
- McClure Company
- McGuireWoods, LLP
- McNees Wallace & Nurick, LLC
- McQuaide Blasko
- McTish, Kunkel & Associates
- Michael Baker Corporation
- Microbac Laboratories Inc.
- ModSpace
- Moody and Associates, Inc.
- Morgan, Lewis & Bockius, LLP
- MSA
- ms consultants, inc.
- MWH
- Nabors Completion and Production Services Co.
- NAES Corporation
- Nalco Company
- National Vacuum Corp.
- National Oilwell Varco (NOV)
- Natural Resource Group
- Nemacolin Woodlands Resort/84 Lumber
- New Enterprise Stone Lime Co., Inc.
- New Pig Energy
- New Tech Global
- O’Brien & Gere
- Ogletree, Deakins, Nash, Smoak & Stewart
- OSC Energy Services
- Oxford Development Company
- Pace Analytical Services, Inc.
- ParenteBeard, LLC
- Parsons Brinckerhoff
- Paul C. Rizzo Associates
- Penn E&R
- Penn State Hospitality Services
- Pennoni Associates, Inc.
- Pennsylvania American Water
- Pennsy Supply, Inc.
- Penn United Technologies
- Pepper Hamilton LLP
- Percheron, LLC
- PetroChoice
- PJ Dick-Trumbull Corporation
- PPG
- PwC (PriceWaterhouseCoopers)
- Protechnics (division of Core Laboratories)
- Prudential Preferred Realty
- R3 Fusion Inc.
- ReedSmith, LLP
- Reserved Environmental Services, LLC
- RETTEW
- Ridge Global
- Ridge Policy Group
- RT Environmental Services
- Russell Standard Corporation
- SAIC (Science Applications International Corporation)
- Saul Ewing
- Saxon Drilling
- SCE Environmental
- Schlumberger Oilfield Services
- Schneider Downs & Co., Inc.
- Schramm
- Select Energy Services, LLC
- SGC Engineering, LLC (Member of The Senergy Group)
- Sevenson Environmental Services
- Skelly and Loy, Inc.
- SSM Group
- Stallion Oilfield Services
- Stahl Sheaffer Engineering, LLC
- Stantec Consulting Corporation
- Steptoe & Johnson
- STRAD Oilfield Services
- STV Energy Services, Inc.
- Suit-Kote Corporation
- Summa Technologies
- Sunnyside Supply, Inc.
- Superior Energy Services
- SWCA Environmental Consultants
- Taylor Wiseman & Taylor
- Tensar International Corporation
- 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 West Firm
- TMK IPSCO
- Total Safety U.S., Inc.
- TRC
- Trinity Consultants, Inc.
- Twilight Services
- United States Steel Corporation
- Universal Well Services, Inc.
- URS Corporation
- Urban Engineers Inc.
- USA Compression
- Valerus
- Vallourec & Mannesmann USA
- Veolia Environment North America
- Waste Management
- Weatherford International Ltd.
- Weavertown Environmental Group
- Weston Solutions, Inc.
- West Penn Energy Services, LLC
- Willbros Engineering
- Williams Scotsman
- Womble Carlyle Ecology Innovations
- Womble Carlyle Sandridge & Rice LLP
- WorleyParsons
