We analyze transmission of a normally incident plane wave through a 100nm diameter hole in a silver film that is filled with a high index dielectric and is surrounded by 300nm wide surface grooves. Specifically, we study the dependency of the transmission efficiency on the number of grooves, groove depth, and the horizontal distance between the groove and the central hole. We observe that the investigated structure exhibits over five orders of magnitude larger transmission efficiency versus a single hole without the dielectric filling.