"This paper examines the process used by USCG Captains of the Ports (COTPs) when petitioned to issue a permit for transportation and loading or unloading of commercial explosives through U.S. ports. Commercial explosives, like many other hazardous materials, are essential to our way of life, but involve some risk when transported. DOT's Research and Special Programs Administrations (RSPA's) risk-based hazardous materials transportation regulations (HMR) are intended to mitigate this risk to an acceptable level. Hazardous materials are permitted to move freely in commerce if the established requirements of the HMR are met. However, explosives, through the imposition of additional USCG COTP measures, are often required to meet a 'zero public risk' safe separation requirement based on Department of Defense quantity-distance (Q/D) requirements for Military explosives facilities when a permit request is made to USCG COTPs."
U.S. Dept. of Transportation, Pipeline and Hazardous Materials Safety Administration: http://www.phmsa.dot.gov/