Date of Award:

5-2015

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Civil and Environmental Engineering

Committee

William Doucette

Abstract

Orbital ATK tests horizontally restrained solid rocket motors (SRMs) in Promontory, Utah, USA. During SRMs tests, an estimated 1.5 million kg (~3.3 million lbs.) of entrained soil and combustion products (mainly aluminum oxide, gaseous hydrogen chloride, and water) are deposited over a wide area. Local farmers have expressed concerns regarding the deposition of this material, referred to as Test Fire Soil (TFS), on crops surrounding the test site.

Greenhouse studies of mature corn and alfalfa (54 days to harvest) exposed to a worse case TFS deposition density to soil (3200-g/m2) resulted in reductions in germination and plant growth. Application of TFS only on leaves caused visual changes in leaf appearance (e.g. “burning”) but did not impact on growth. The visual damage to the leaves was thought to be caused by the high chloride in the TFS. The pH (measured from 2-10 in the field) of the TFS was also thought to be a potential cause of the visual damage.

Follow-up studies were conducted using younger corn, alfalfa and winter wheat (12-54 days from emergence), to evaluate the impact of a more typical TFS deposition density and application scenario. The relationship between deposition amount and the crop impact was also examined. Impact was evaluated by comparing the growth, tissue composition (focusing on chloride and aluminum) and chlorophyll content of controls relative to the treatments. The individual effects of chloride and pH on corn leaves were determined by monitoring visual appearance and chlorophyll content.

Leaves exposed to a typical TFS deposition loading (70-g/m2) did not contain elevated chloride or aluminum levels relative to the controls. Higher TFS loadings (700-g/m2 and 3200-g/m2) resulted in significantly elevated chloride content in corn leaves at 29 days from emergence. Corn leaves treated with TFS at the 700-g/m2 loading 12 days from emergence had comparable chloride levels to controls. High and low pH and chloride solutions visually impacted corn leaves and reduced leaf chlorophyll.

This study indicated SRMs testing can be conducted under typical conditions during the juvenile growth stages of field corn, alfalfa, and winter wheat without adverse impact on crop yield and plant tissue composition.

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