Among the main activities involved in the construction of the dam, there were the consolidation grouting and the completion of the interceptor drain and the grout curtain. In the initial project, it was estimated 1,989 m of drilling, with a diameter of 50 mm, which meant strong dust generation.

One of the main inconveniences of the dust generated from this type of activity is the large distance at which it can be spread, which possibly affects the nearby urban areas on especially windy days. Also, the large number of meters of drilling in concrete could be a source of pollution of river water Alcollarín.

To avoid dust from spreading, FCC CONSTRUCCION decided that all the machinery that was to be used in drilling activity had to use a dust humidification system.

The water mains installed adjacent next to the dam were used to connect the hoses to the drilling machinery.

In addition to the environmental advantages of this action, it has also little technical difficulty and low fi- nancial cost, as no additional installation is necessary. Furthermore, it is a quickly to apply method which does not affect the execution of the works and which facilitates cleaning, as all of the material remains next to the hole drilled.

• By implementing this Good Practice, we minimised the amount of dust generated during drilling, leaving the drilled material next to the hole, which also greatly simplified its later cleaning.
• Tests performed by specialists of the University of Extremadura, in conjunction with FCC Construcción, confirmed that, thanks to the measures adopted, the impact on the atmosphere and the river water was nil.