Minnesota Vikings stadium planners are identifying and starting to address environmental issues before construction begins. The Minnesota Sports Facilities Authority on Thursday published hundreds of pages of data and analysis. The environmental impact statement notes soil contamination that will be studied further and mitigated as needed. The stadium will be built where the Metrodome now stands in an area that once housed significant industrial operations. To deal with concerns that translucent elements of the stadium could cause risks to migrating birds, officials say they will turn off lighting in overnight hours in spring and fall. The $975-million stadium should be more energy efficient than the 30-year-old Metrodome. For instance, annual water use in the Metrodome is 18-million gallons compared with an expected 10-million at the new facility.