If the spaceport in Ka’u gets off the ground, the several hazardous compounds used as rocket propellants will have to find their way to Palima Point. According to the as-yet unreleased draft environmental impact statement prepared for the Department of Business, Economic Development and Tourism, the propellants will be carried by truck from Hilo Harbor down state Highway 11 for seventy or so miles to the spaceport. En route, the trucks will travel through densely populated areas of Hilo as well as through the Hawai’i Volcanoes National Park, with its myriad endangered species of plants and animals. Hilo’s Banyan Drive, along which are to be found almost all of its tourist accommodations, is not directly along the route but is close enough to be engulfed by toxic fumes under certain unfortunate circumstances.
The DEIS states that the following propellants or other substances used in spaceport operations will be unloaded from ships at the port of Hilo and trucked to the spaceport: solid-rocket motors; cryogenic, or super-cold, liquid oxygen, liquid hydrogen, liquid helium, and liquid nitrogen; and hypergolic fuels including hydrazine (N2H4), unsymmetrical dimethyl hydrazine (UDMH), Aerozine-50 (a 50-50 blend of hydrazine and UDMH); monomethyl hydrazine (MMH), and nitrogen tetroxide (N204). (Hypergolic fuels are ones that ignite spontaneously when they come in contact with a complementary fuel.)
As one might expect, an accident involving any one of these substances can, under some circumstances, threaten public health, property, and environmental resources. Studies included in the appendices to the DEIS describe what might happen if an accident were to result in release of some of these chemicals to the atmosphere.
Best-case Worst-case
A firm called ACTA, based in Torrance, California, performed most of the studies that describe possible accident scenarios for propellant transport. According to ACTA, a typical truckload might contain up to 16 55-gallon drums of the hydrazine fuels. Nitrogen tetroxide would be transported in 30-gallon cylinders, and as many as nine of these cylinders might be packed onto one truck.
Cryogenic liquids would be shipped in truck containers of 3,000 or 4,000 gallons. The solid-rocket motors would be transported in specially built crates on flat-bed trucks.
ACTAs descriptions of possible accidents are stated to be “worst-case.” Nonetheless, ACTA assumes that under no circumstances will more than one container (drum or cylinder) rupture in the event of an accident.
To determine the areas where concentrations of a spilled chemical would be high enough to affect human health, ACTA used a computer model -AFTOX- developed by the Air Force for “cold spill dispersion analysis.” When temperatures and wind conditions are plugged into the model as well as the size of the pool of spilled chemical, the computer program comes up with descriptions of “plumes,” which represent the path taken by the cloud containing concentrations of the spilled chemical sufficiently high to be of concern to human health. Two plumes are described for each chemical: one describing a day-time release (assuming prevailing trade winds) and the other describing night-time conditions (assuming less vigorous night-time winds in a makai direction). These plumes, whose two-dimensional representations look like elongated disks, are then laid over a map of the area where the spill is supposed to have occurred, indicating the areas that may need to be evacuated.
ACTA’s report on transportation hazards consists mainly of these maps. For each chemical of concern, plumes were computed indicating possible daytime and night-time drifts. Seven sites assumed to be the most hazardous along the route to Palima Point were selected for analysis: Site I is at Hilo Harbor; Site 2 at the intersection of Banyan Drive and Highway 11 (next to Ken’s Pancake House); Sites 3 and 4 are two major intersections along Kanoelehua Avenue (Highway 11), near shopping centers and schools; Site 5 is along Highway 11 just before the intersection with Highway 130 at Ke’aau (the particular site selected is described as being where the four-lane highway ends: in fact, Highway 11 continues to be four-lane for perhaps another mile beyond the point chosen for study); Site 6 is on Highway 11 near the entry to Hawai’i Volcanoes National Park; Site 7 is a mile or two south of that, where the road runs between Kilauea Military Camp to the east and Volcano Golf Course to the west; finally, Site 7 is at the turn-in to the proposed spaceport site at Palima Point.
Hold the Hot Sauce
Assuming the plumes to be accurate, they represent the area within which chemical concentrations will exceed short-term public emergency guidance levels, or SPEGLs. These are standards designed to be protective of the most sensitive members of the public. Yet, as noted in another DEIS appendix1, “it is possible within these contours [that] concentrations may be higher.” In other words, the chemicals that may pass over a given area at the center of the plume will be more concentrated than they are at the edge.
To put it in more prosaic terms, people eating the Mexican omelet at Ken’s will have substantially more to worry about than the hot sauce if a 300-gallon container of nitrogen tetroxide spills outside the restaurant door. People fishing at Waiakea Mill Pond, on the outer edge of the plume, might notice nothing more than a nasty smell.
If winds are from the south, the plume would cover the hotels along Banyan Drive. If winds were from the southwest, the plume would reach the homeless camp at Onekahakaha Beach Park.
ACTA underestimates the potentially exposed population at Kea’au by locating the theoretical site of an accident about half a mile from the intersection with Highway 130 (the Kea’au-Pahoa Road). If the plumes described on ACTA’s map for a spill of nitrogen tetroxide were centered on the intersection, the Nine-and-a-half Mile Camp would be included in the area where SPEGL concentrations are likely to be exceeded. Houses in the Eight-and-a-half Mile Camp would be covered in the night-time plume depiction.
The SPEGL contours at the two park sites include Kilauea Military Camp and park employee housing. Twist the plume – by supposing winds during the day were a bit more easterly – and the residences along the Volcano Golf Course would be blanketed in nitrogen tetroxide as well.
No ‘Severe Effects’
Liquid propellants are extremely toxic, even at small concentrations. Nonetheless, ACTA states in its conclusions that “the toxic contours … are based on SPEGLs that are associated with mild effects to the most sensitive population groups. Even the most sensitive individuals exposed to these toxic levels will not be subjected to severe effects. The effects from the exposure may be minor – slight to no irritation to skin or eyes; merely coughing, etc.” Yet, as noted above, within the areas of elevated concentrations, the exposure levels can exceed the short-term public exposure guidelines. In addition, some of the chemicals are noticeable as bad smells at concentrations far lower than the SPEGLs. (Nitrogen tetroxide, to stick with this example, is detectable by some people at 0.11 parts per million; most people notice it at 0.22 ppm. By contrast, the nitrogen tetroxide SPEGL for one hour is 2 parts per million.)
In another sense, the use of SPEGLs is of limited value. They refer to exposures that are averaged over a certain time span (usually 30 minutes, one hour, or 24 hours). Peak exposures may be many times greater than exposures that are averaged over longer periods. If these peak exposures to a given chemical are great enough, or the individual exposed is sensitive enough, people can die from the effects, even though the overall time-averaged SPEGL for that chemical is not exceeded.
Lift-Off
Solid-rocket motors can, under some circumstances, explode before launch. According to ACTA, “shock-induced ignition and/or explosion of ammonium perchlorate-based propellant is a possibility. A person was killed at Edwards Air Force Base not too long ago as the result of the explosion of a Titan IV solid motor segment that dropped from 80 feet.”
Solid-rocket motors might also be set off by exposure to high temperatures. The temperature of a gasoline fire can reach about 3500 degrees Fahrenheit, ACTA notes. “Direct exposure of HTPB [hydroxy terminated polybutadiene] propellant to the flame temperature of a gasoline fire for more than a few seconds would ignite the propellant,” ACTA states, but adds: “The probability of direct exposure of the propellant to a gasoline fire is, however, considered to be low.”
Finally, ACTA notes that the SPEGL contours for a spill of chlorine are not vastly different from those for any of the propellants. The purpose of analyzing the SPEGL contours for chlorine, ACTA states, “was to compare the risk from transporting rocket fuels with that associated with the transportation of chlorine. Chlorine is used and transported throughout Hawai’i and so it can reasonably be assumed that the associated transportation-related risk is tacitly accepted by the local population.”
1 Volume VIII, Appendix B, “Ecological Risk Assessment,” by Risk Science Associates, 1993, pages 3-13.
Volume 4, Number 2 August 1993
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