I am just a DIY homeowner, not a pro...but I have a few thoughts. Since it is dry, what using about some odor absorbent like baking soda or charcoal. Another idea would be spraying a little bleach or bleach/water mix.

Casey

"http://www.driverdb.com/Sean McDonagh"

Thanks for the reply. I did put 2 "Odor-Blitz" containers in the area under the steps but it didn't do much. I put a humidity gauge in the sump area and one out in the living area of the basement. The one in the sump area reads 70% while the other reads 60%. I have since put a fan and a dehumidifier under the steps and it lowers the humidity to 60% but the smell is still present. On the exterior side of the block walls surrounding the under stairs area where the smell is I have landscaping and mulch. I have since dug up the dirt along the wall and it seems to have the same odor. I think I'll try cleaning the block and sealing it with waterproofer to seal it in case the smell is coming from the outside. I still don't know why my drain tile is plugged with dry sand though.