MYRTLE BEACH — Environmental groups are challenging the federal permits that allow construction of Interstate 73, a project that is the longtime dream of Grand Strand tourism officials. The lawsuit was filed by the Southern Environmental Law Center on behalf of the Coastal Conservation League. It claims the Army Corps of Engineers relied on an outdated environmental study and did not consider alternatives to I-73 as it issued permits this June to begin work on the road, therefore violating federal law. Catherine Wannamaker, an attorney for the SELC, said that the agencies involved in issuing the permits were stuck on...