Yes, the toxic coal tar beneath Thomas Greene Playground in Gowanus is said to be far enough underground that it doesn’t pose a threat to, say, children on slides. Still, it’s unsettling to find a sign about the “remedial investigation” of pollution there. A GL reader sent in this shot, which comes from the Third Avenue side of the park. It is one of several sites in Gowanus that once were the site of Manufactured Gas Plants and that need to be cleaned up.