Working with a local survey coordinate system but need to work also to national grid to use aerial photography, GIS files and also work in InfraWorks?
So you need is to create a local grid survey coordinate system.
My colleague in Premium Support Lucy Kuhns, who is also a guru in survey has created two short videos to explain the process.
You need to know your grid origin Lat and Long value and you then can setup in a couple of minutes
(this technique does support for rotation or geoids)