Abel Construction Co., Inc.
ACCO Chain & Lifting Products Division
ADI Systems, Inc.
Advance Tank & Construction Company
Ahlstrom Paper
Allied-Signal Aerospace Company
Ameresco Delaware Energy, LLC
AMZ Manufacturing Company
Aqua Pennsylvania, Inc.
Artesian Water Company
Armstrong Service, Inc.
Armstrong World Industries, Inc.
Aspen Systems
AT&T
Aventis Pasteur, Inc./Sanofi-Aventis
BAE Systems
Baker Refractories
Black & Veatch Construction
BMY
Bulova Technologies, LLC
Burle Industries, Inc.
Cabot Performance Materials
Caldwell Tanks, Inc.
CB&I Constructors, Inc.
CGA Law Firm
Church & Dwight Company, Inc.
C-P Converters, Inc.
Chef Francisco of PA, Inc.
Chesapeake Finished Metals, Inc.
Chicago Bridge & Iron Company
College Hill Poultry
Columbia Gas Company
Columbia Water Company
Congoleum Corporation
Constellation Energy Source
Cumberland Valley School District
Drees Homes
Dreyer’s Grand Ice Cream
Dryden Oil Company
ECS Mid-Atlantic LLC
Edgecomb Metals
Exelon Power
Fairchild Semiconductor
Faison-Dunkirk, LLC
Fisher Tank Company
Gas Technology Products
General Dynamics
General Electric Company
Glatfelter Paper
Graham Architectural
GROWMARK FS, LLC
Harris Corporation Semiconductor Products Division
Harrisburg International Airport
Heinz U.S.A.
Hervitz Meat Packing Plant
Helena Chemical Company
Hershey Farm, Inc.
Hershey Foods
Hewlett-Packard Co.
Homestead Mobile Home Estate
Intersil Corporation
JHG Contractors, Inc.
Keystone Potato Products

Kinsley Construction

Kodak Processing Labs
L&S Sweeteners
Logos Academy
Lucent Technologies
Maryland Environmental Service
McCormick & Co., Inc.
McNaughton Homes
Merck & Company, Inc.
Millennium Inorganic Chemical
Milton Hershey School

National Security Agency
NGK Metals Corporation
Norfolk Southern Corporation
Northrop Grumman Systems Company
Occidental Chemical Corporation
Osram Sylvania
Penn National Gaming, Inc.
Penn State Investment Group
Pennsy Supply
Pennsylvania American Water Company
P.H. Glatfelter Company
Pitt-DesMoines, Inc. (PDM)
Playskool
Precoat Metals
Record Club of America
Republic Services, Inc.
Richmar Builders, Inc.
Roaring Creek Water Company
Rohm and Haas Company
Rutgers Organics Corporation
SCS Engineers, PC
Shire Pharmaceuticals
SKF USA, Inc.
Solar Power Industries, Inc.
Spring Glen Fresh Foods
Sun Chemical
Sunoco, Inc.
Susquehanna Pfaltzgraff Company
Sweetheart Cup Company, Inc.
Sybron Chemicals, Inc.
The York Water Company
Thomson Consumer Electronics
The Gettysburg Foundation
Tidewater Utilities
Titanium Wire Corporation

Triple Crown Corporation
UGI Utilities, Inc.
United Defense Limited Partners
United Water PA, Inc.
Universal Foods Corporation
U.S. Filter
Washington Metropolitan Area Transit Authority
Waste Management, Inc.
Waste Management of Pennsylvania
White Marsh Environmental
Whitmoyer Labs
Worthington Steel