By working in those projects as an engineer or as a technician, you are not involved in any riba activity. `Abdullah ibn Mas`ud narrated that the Messenger of Allah (peace be upon him) cursed the one who accepted usury, the one who paid it, the witness to it, and the one who recorded it. (Muslim and Abu Dawud). This is the version of Abu Dawud. As long as you do not register, witness, undertake or participate in interest taking or giving, your job is halal and there is no harm to continue doing it.