Plans are underway to create a huge urban park in New Jersey that would be 10 times the size of New York City’s Central Park — on land now pocked by old garbage dumps and sewage sites. Unofficially dubbed the Meadowlands Preserve, the new park would encompass 8,400 acres of wetlands and green space, and would include sports fields, fishing piers, golf courses, and 35 miles of hiking trails. The master plan calls for remediating areas polluted by landfills — no small task. But park boosters are encouraged by the wildlife that has already returned to the area in recent years. “A few years ago, if you had told anyone this collection of toxic dumps and marshes would one day become an environmental park, people would have thought you were crazy,” said Rep. Steve Rothman (D-N.J.), who helped secure more than $4 million in congressional funding for land purchases intended to go toward the park. Local businesspeople are getting excited about the ecotourism possibilities and plan to promote bird-watching and kayaking in the area.