| 1959 |
Heredia y Moreno, HEYMO, was established as a professional Association |
| 1960 |
Numerous projects for the U.S. Navy (O.I.C.C) in the Spanish American military bases.
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| 1964 |
The Professional Association was transformed into a Joint-Stock Company: Heredia y Moreno, S.A. Its activity was centered around the execution of civil engineering and building projects like the Spanish Pavilion in the New York World Fair, the Glass Pavilion in Madrid Fair or the Fierros Group Building in Madrid |
| 1966 |
HEYMO extended its areas of activity to industrial plants, industrial installations, and chemical process plants and started its activities abroad.
HEYMO signed its first “turn key” contract for a fertilizer plant in Venezuela
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| 1968 |
Continued activity in “turn key” projects abroad: The Durán-Quito oil pipeline in Ecuador, the Meliá Hotel in Baghdad. |
| 1969 |
1969 The beginning of environmentally related activities: waste water treatment plants for Abonos Sevilla, Minnesota de España and several industrial parks and residential states.
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| 1972 |
HEYMO established a joint-venture with the Algerian Government, to study, design, and supervise the construction of the National Gas Transportation and Distribution System, establishing the bases for present important know-how in this area.
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| 1976 |
With the collaboration of Jaakko Pöyry OY, HEYMO developed its first complete pulp & paper project (Papelera Navarra), consolidating its position as the Spanish engineering company with the most references on the P&P area.
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| 1980 |
HEYMO started its activities in energy and agriculture and food industry. |
| 1988 |
The  GROUP holds the majority of HEYMO's stock.
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| 1992 |
HEYMO started to work on Maghreb-Europe Gas pipeline: routing and basic design of the Moroccan section. |
| 1993 |
Start up of the Sarrió Tisú (Jamont Group) paper mill Alo, Navarra - Spain. |
| 1995 |
High activity in industrial plants, oil and gas transport systems, cogeneration and infrastructure in Spain and abroad (Bosnia, Mozambique, Morocco, Venezuela).
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| 1997 |
New presence in the EPC market: CHP plants and oil products storage. Activity in telecommunications area, with projects in Spain, Venezuela and Brasil.
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| 1998 |
Restarted presence in turnkey market in cogeneration plants and oil storage systems. New activity in telecommunications sector with projects in Spain and Venezuela.
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| 1998-9 |
Energy supplies to Barajas Airport |
| 2000 |
High Activity in Power Plant . Creation of the Energy Business Area. |
| 2001 | Aluminiun smelter plant |
| 2002 | Combined cycle peaker power plant, 250 MWe for Global 3 Energy in Escatrón (Zaragoza – Spain). H2 and CO2 plants for Air Liquide in Puerto Llano (Ciudad Real) and A Coruña |
| 2003 | HEYMO re-structures in 5 business area, according to the Jaakko Pöyry Oy Energy Business Group (Electrowatt-Ekono). Energy efficiency studies for the Administration (IDAE). Thermal oxidizer for Repsol Química in Puerto Llano (Ciudad Real). Activity starts in Kyoto gases emission studies and trade |
| 2004 | A-400M military transport plane assembly plant in Seville, EADS-CASA. Owner's engineering for several 400 MWe combined cycle plants in Congosto, La Robla and Zaragoza for Global 3 Group. Owner's engineering for the extension of a OP/SM plant in Tarragona for REPSOL QUÍMICA. Engineering services for a 50 MW combined cycle cogeneration plant and a new paper machine for SAICA-4
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