ARCADIS Takes Part in Sale of Carbon Credits.

ARNHEM, The Netherlands -- ARCADIS (NASDAQ: ARCAF, EURONEXT: ARCAD) today announced that Biogas, a partnership of the Brazilian ARCADIS Logos with the Dutch Van der Wiel and the Brazilian Heleno Fonseca Construtechnica, has signed a contract for the sale of carbon credits. Under the contract 1 million tons of carbon credits will be delivered to the German bank KfW in twelve months, starting June 2006, once the final verification report is issued. The carbon credits have been produced and validated according to the Kyoto Treaty. ARCADIS' ultimate share is 16%. KfW acquired the carbon credits for buyers within the European Union's Emission Trading Scheme (EU ETS), which was established to allow trading of CO2 emission reduction certificates (CER).

In 2003, Biogas developed the largest landfill gas energy plant in the world, producing 170 million kWh per year of electrical power from methane extracted from Sao Paulo's Bandeirantes landfill. The methane gas from the landfill is hazardous to the environment and affects global warming. Methane gas is considerably more harmful to greenhouse problems than CO2. Also, by using the methane gas instead of fossil fuel for generating energy, additional emission of CO2 is being avoided.

"This contract is a good example of the way ARCADIS takes a leading role in developing projects that contribute to improving our environment. We are taking pride in being involved in the reduction of global warming effects. I expect that more contracts will follow in the field of certified emission reductions", says Harrie Noy, CEO of ARCADIS.

ARCADIS is an international company providing consultancy, engineering and management services in infrastructure, environment and facilities, to enhance mobility, sustainability and quality of life. ARCADIS develops, designs, implements, maintains and operates projects for companies and governments. With more than 10,000 employees and over EUR 1 billion in gross revenue, the company has an extensive international network that is supported by strong local market positions.

Except for historical information contained herein, the statements in this release are forward-looking statements that are made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Forward-looking statements involve known and unknown risks and uncertainties that may cause the company's actual results in future periods to differ materially from forecasted results. Those risks include, among others, risks associated with possible changes in environmental legislation and risks with regard to the Company's ability to acquire and execute projects. These are other risks are described in ARCADIS' filings with the Securities and Exchange Commission over the last 12 months, copies of which will be available from the SEC or may be obtained upon request from the Company.