Scientists and engineers are using radar to determine the safety of a sand dune at the Indiana Dunes National Lakeshore that collapsed onto a 6-year-old Illinois boy, burying him under 11 feet of sand last month.  EPA spokesman Francisco Arcaute (AHR‘-koot-ay) says the  gear they‘re using at Mount Baldy is usually used to do underground searches at hazardous waste sites.  But he says they definitely do not think anything hazardous is there under the dune.  Arcute would not speculate on what caused the sand pocket to swallow Nathan Woessner (WAYS-ner), but they hope to gather some solid scientific information that could lead them to find the cause.  I-U Northwest geosciences professor Erin Argyilan (AHR-guh-lin) says what the EPA and National Park Service team is doing is the right way to investigate the Mount Baldy issue.  Arcute says the team will remain at the dunes for at least one more day, but may need more equipment and more time to conduct the investigation.