Date of Award:

5-2013

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Civil and Environmental Engineering

Committee Chair(s)

Laurie McNeill

Committee

Laurie McNeill

Committee

William Doucette

Committee

Bruce Bugbee

Abstract

Alliant Techsystems, Inc (ATK) manufactures solid rocket motors for the National Aeronautics and Space Administration (NASA) at the Promontory, UT facility. Periodically ATK conducts static test fires, where the rocket is restrained horizontally and fired into a hillside. The plume entrains native soil and is carried by the wind until it cools and settles. Although the area around ATK is sparsely populated, residents of nearby Penrose and Thatcher, UT are concerned with the deposition of the test fire soil (TFS) from the static rocket tests. In 2010, several crop fields nearing harvest were dusted with TFS, prompting the investigation of its effects on corn and alfalfa.

The objective of this research is to determine the impacts of TFS on the germination, biomass production, and plant composition of corn and alfalfa exposed to TFS deposition. One significant component of TFS is chloride, an inorganic anion that induces salt stress in plants. If large amounts are deposited, TFS contains enough chloride to prevent germination and reduce growth. This study was designed to determine the effect of a worst-case scenario, 1 inch of TFS deposition, which is the maximum amount that has been observed historically.

Germination studies were performed with various concentrations of TFS in soil. The highest concentration evaluated was 10% TFS in soil. This concentration was calculated from the worst-case deposition scenario, one inch of TFS tilled into the top 10 inches of soil. At concentrations of 1 - 10% TFS, germination was reduced, but below 1% TFS, no effect was noticed. A germination study was performed after washing the TFS with artificial rainwater. After 7 days there was no significant difference between corn germination in the leached TFS and controls, indicating that the adverse effects of the TFS can be mitigated by washing the chloride out of the root zone.

Biomass production was measured by weighing the tissues collected from plants exposed to TFS in a greenhouse. Exposure to TFS occurred in either the soil (root zone) or on the leaves of the plant. Plants treated with TFS in the root zone had severely reduced biomass production. Corn did not produce any appreciable yield, and alfalfa production decreased drastically after exposure to TFS.

Plant tissue was analyzed for metals and anions. Corn and alfalfa exposed to TFS in the root zone accumulated higher levels of metals and nutrients than controls and foliar-treated plants. Plants whose leaves had been treated with TFS accumulated more aluminum than controls. Although treatment caused significant differences in plant composition, the metal or nutrient levels were not high enough to be considered detrimental to plant health.

This study shows that high amounts of deposition from static test fires at ATK could result in damage to field crops especially during more sensitive growth stages. Adopting test-fire guidelines that will reduce TFS deposition on seeds and young plants may reduce the impacts of static test fires and prevent crop damage. Conducting test fires after harvest would further prevent the change in plant tissue composition. Providing extra irrigation to soil impacted with the TFS may also help to mitigate potential impacts.

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Comments

This work made publicly available electronically on December 21, 2012.

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