ANDREWS — Rose Gardner inflated balloons for her grandson’s birthday party recently at her floral shop in Eunice, N.M., and talked about nuclear waste.

“I’m just really respectful of radiation and its effects,” she said, a reason she became involved in the Sierra Club and its legal battle with Waste Control Specialists, which operates a radioactive waste site in nearby Andrews County, Tex. “Some people may say I’ve gone overboard, but I don’t think I have.”

The Sierra Club is suing on behalf of Ms. Gardner and two residents of Andrews to have its claims heard in court. In legal action against W.C.S. dating to 2007, the Sierra Club has challenged the company’s state environmental licenses because of the discovery of groundwater in some of the waste disposal site’s 520 monitoring wells.

But officials with the company, which is owned by the Dallas billionaire Harold Simmons, say the site is safe. And Andrews County has joined the battle, suing the Sierra Club in a bid to end its legal claims. (The Harold Simmons Foundation is a major donor to The Texas Tribune.)