pattibee, as far as I know, all sump pumps carry a filter to prevent particles above a certain size from entering the impeller chamber. In your circumstances, I expect that the pump will shut down or burn out when the sand clogs the filter. There are 'sludge pumps' but I have no experience in their operation.

pattibee,

A suggestion is a pre-filter around the sump inlet filter and raised just off the bottom would allow the sand to drop off the pre-filter when the pump was turned off. Reverse slope the sides of the pre-filter. Might work depending on water time and flow needed. The slower the velocity (larger pipe inlet and pipe size) of the water the less filtration needed. GL. Aloha

You might want to check with you state to see if you are even allowed to, some are very persnickity about wells and their useage.