Wal-Mart Watch: Yet another kind of standard Wal-Mart got caught pushing down: Wal-Mart Stores Inc., the nation's largest retailer, will pay a $3.1 million fine to settle a Clean Water Act violation stemming from excessive storm water runoff from its construction sites, federal officials said Wednesday. Wal-Mart also agreed in the settlement with the Environmental Protection Agency and Justice Department to improve runoff controls at the more than 200 sites each year where the company builds stores, including Sam's Club outlets.