GRAND ISLAND, NE -- In late November, the city of Grand Island, Nebraska declared a sewer emergency after a sewage feeder line malfunctioned at the city's wastewater treatment plant. The problem was corrected after Grand Island diver Dave Lemburg volunteered to dive into the waste and fix a broken valve.After 20 minutes submerged in the waste, Lemburg fixed the problem. Today Lemburg looks through a stack of thank you letters. For the past week, he's been receiving 5 or 6 day. Most are addressed to "the Grand Island hero", almost all are from strangers."I haven't had a chance to sit down and count today's but probably another 5 or 6, so close to 30 cards," said Lemburg.Some send money, others try humor -- all show gratitude. Dave Lemburg is making quite the name for himself, but he remains humble."I did this out of the kindness of my heart, not to win any awards I'm just another grand islander like everyone else," Lemburg said. "It was the nastiest stuff you'll ever encounter, but if I'd kept calling it that I'd never have gone down to do the job."Dave's a volunteer with the city's dive and rescue team. He didn't have to do this -- a fact his wife quickly reminded him."She kind of gave me that look and she said, "you're not going," and I said, "I'm going. Good bye", said Lemberg.The sewage current was strong, so Dave strapped 40 pounds of lead onto his scuba gear and was lowered down on a rope."Luckily the rope was just at the right length, the valve right in front of me," he said.Now about three feet below the surface, Dave found the valve by feel. He would spend the next 15 minutes trying to close the valve with a wrench. Slowly the sewage began to go down."You have to mentally block all of the nasty stuff out and look at the situation at hand. I thought of all those people's basements and Christmas coming up, and I thought "this would not be good," said Lemburg.Dave says even diving for bodies does not compare to this mission.