N.H. Code Admin. R. Env-Wt 902.06
“Closed-bottom culvert” means a culvert that has a solid top, solid sides, and solid bottom, such that its cross-section is continuous. The term includes a closed-bottom culvert of any shape in cross-section, including but not limited to square, rectangular, circular, or oval.
Source. #12809, eff 12-15-19