RICHLAND — Video inspections are planned out of an abundance of caution after a small, unexplained hole in the ground was discovered near an underground tank storing radioactive waste at the Hanford nuclear reservation. Work was being done Thursday to compact earth in preparation to add an asphalt covering over the soil at the SX-Tank Farm in the center of the reservation. The farm has 15 single-shell tanks, each with a 1-million gallon capacity.