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The current US Environmental Protection Agency (USEPA) maximum contaminant level (MCL) for total chromium of 100 ppb is under revision to consider a specific level for Cr(VI), which has a proposed MCL of 10 ppb in California. Cr(VI) is a suspected carcinogen, and interconverts with the other most commonly found chromium species, Cr(III). To regulate and further understand the behavior of Cr(VI) in water systems, appropriate sample preservation methods are essential for accurate measurements. The ammonia buffer (recommended by EPA) was proven to be the most effective preservation when a holding time of 14 days is considered. Apart from proper Cr(VI) preservation, sampling at an appropriate site is important for determining the public's exposure to Cr(VI). The proposed MCL for Cr(VI) in the state of California will be monitored at the entry point of distribution systems. To the extent that Cr(VI) is formed in the distribution system or in water contacting plumbing, measurements at the treatment plant might not reflect consumer exposure at the tap. Cr(VI) can be released to drinking water from Cr present in stainless steel alloys. At the maximum residual disinfectant level (MRDL), Cr(VI) formation decreased in the order chlorine dioxide > chlorine > chloramine. Less Cr(VI) was released from stainless steel at lower pH in the presence of chlorine, but the opposite trend was observed for chlorine dioxide. Stainless steels with a higher chromium content tended to release more Cr(VI). / Master of Science

The purpose of this research was the investigation of the corrosion behavior of a low chromium-content stainless steel, ASTM A1010, for use in steel bridge members. This stainless steel has been marketed as a potential replacement for conventional structural steels for bridges located in highly-corrosive environments, with the potential to provide life-cycle cost savings. Further investigation of the corrosion behavior of A1010 in corrosive environments was required for three bridge-specific applications: the galvanic corrosion of A1010 connected to plates and fasteners composed of dissimilar metals; the crevice corrosion of A1010 plates connected with other A1010 plates; and the effect of varying surface preparation techniques on the corrosion behavior of A1010. These behaviors were studied through the implementation of an accelerated cyclic corrosion test, the modified SAE J2334 Surface Vehicle Standard specification. Results from the accelerated corrosion test indicated the following: galvanic corrosion rates of A1010 with dissimilar metal plates may result in accelerated corrosion rates of the dissimilar metal plates beyond desirable levels; connections to many non-stainless fastener types show cause for concerns with galvanic corrosion, while B8 Class 2 austenitic stainless steel bolt assemblies exhibited superior performance; the relative corrosion-resistance of A1010 is decreased in detailing susceptible to crevice corrosion; and finally, numerous abrasive blasting procedures appear to be suitable for use with A1010. / Master of Science / The purpose of this research was the investigation of the corrosion behavior of a recently-developed stainless steel, ASTM A1010, for use in steel bridges. This stainless steel has been marketed as a potential replacement for conventional structural steels for bridges located in highly-corrosive environments, and has the potential to provide cost savings to bridge owners over the life of the bridge. While the general properties of ASTM A1010 have been studied, further investigation was required for the corrosion behavior in bridge-specific applications. As a result, the corrosion behavior from three applications was investigated: A1010 connected to plates and fasteners composed of dissimilar metals; A1010 plates connected with other A1010 plates; and A1010 cleaned using different abrasive blasting procedures. Ultimately, these behaviors were studied through the implementation of an accelerated laboratory corrosion test which exposed A1010 plates to repeated cycles with controlled temperature, relative humidity, and exposure to corrosive substances. Testing results have shown important findings: significant concerns are associated with connecting different plate types to A1010 due to the high rates of corrosion expected on the dissimilar metals; connections to many fastener types show cause for concern, while one stainless steel type exhibited superior performance above the rest; the relative corrosion-resistance of A1010 is lessened in highly-corrosive environments; and finally, numerous abrasive blasting procedures appear to be suitable for use with A1010.