(AP) — A 63-year-old man is scheduled to be in a Polk County courtroom next week to face charges connected to an explosion that severely injured a 14-year-old relative.

Court records say the hearing is set Thursday for Russell Hilger, of David City. The charges include two for assault.

Authorities say Hilger made an explosive device by putting black powder into a pipe and covering it with towels. Then he set it off on July 4 last year during a family gathering at Ernst Lake, which sits a few miles south-southwest of Columbus.

Shrapnel from the device hit Lauren Campbell, who was in a tent. She spent two weeks in a hospital for treatment of internal injuries. Hilger is her great-uncle.

Hilger and his attorney have declined to comment.