specified amount preferably at least by a factor of 2 the nozzle 8 and the exhaust air channel 16 and its guide element 20 that is flexibly arranged and or embodied and or the in flow opening of the exhaust air channel 16 extend largely and or at least approximately across the entire width of the apparatus thus in accordance with the invention the excess sand 23 or other foreign material present on the grassy surface 22 is blown out by means of the propelling stream 9 or the air exiting from the nozzle 8 and is transported into the exhaust air channel 16 via the guide element or guide sheet 20 the apparatus can be moved across the grassy area 5 in the working direction indicated by means of the arrow 24 whether manually or by means of a drive not shown here associated with the roller or rollers 4 the cover 14 can be pivoted by means of a joint about a point of rotation or axis of rotation 26 with respect to the basic housing 2 and the cover 14 furthermore contains outlet openings in particular in the form of a perforated sheet 27 for the exhaust air 18 due to gravity the sand or other foreign material transported by means of the air falls downward into the collection container 12 according to the arrow 28 out of the air stream flowing past and above the collection container 12 and is segregated.