Bismillah

Thank you for your question. When ijma and the aql are included in the sources of Islamic law in the school of Ahl al-Bayt (as) it is with specific terminological meanings that are not the same as other schools of thought. 

Ijma is a source of law if the view of the Imam (as) is included within the view of the community. Not when the community is agreed without the opinion of the Imam (as) being included.

The aql is a source when specific intellectual principles are used that are certain, such as the necessity (wujub) of something dictates the necessity of its introductory aspects. For example, the wujub to make wudu for prayer dictates the wujub of exhausting all means to find water to perform that wudu. Further details of these principles can be found in the books of usul al-fiqh.

May you always be successful.