Chad Elgert, 35, a North Sioux City Speedy Rooter sewer company employee, remains in critical condition at a local hospital after he tried to rescue another worker in the same sewer. Elgert had been called to fix a clogged sewer in a one-block stretch of Souix City, IA recently when his co-worker, Robert Thompson, 54, fell into unconscious from the gasses in the sewer. Elgert then descended into the manhole to try to rescue Thompson, but he was also overtaken…