Theses and Dissertations Collection

This three-paper dissertation attempts to address research gaps amongst stormwater management design and engineering education research. The common linkage between the three papers was to conduct research that meets academic standards and results in research findings that could be applied by practitioners to develop practical design and educational solutions to practical problems. In addition, each study incorporated a collaborative approach with different communities to assist with developing and conducting studies that result in recommendations for practical applications. The abstract for each paper is included in this section.

Chapter 2 Abstract

Paper Title: Culturally Relevant Engineering Education (CR-EE): Exploring the Impact on Native American Elementary Students

Native Americans were the original engineers in the United States; however, they are now the most underrepresented ethnic group in the engineering profession. Recommendations for increasing their representation start with the ability to deliver culturally relevant K12 engineering education. However, relevant research is limited to theoretical strategies that lack empirical evidence. This paper describes a case study that involves the collaborative development and implementation of culturally relevant engineering educational (CR-EE) curricular activities with a Tribal Community, Tribal Teachers, and University Researchers. The following research questions guided this study: What factors engage students in the activity? How are Native American students’ perceptions of engineering influenced by participating in a culturally relevant engineering design activity? How did the Tribal community and other group’s involvement influence the students’ responses? The case study includes two separate 3-hour events with 122 elementary students from a public school located on a Tribal reservation. Both qualitative and quantitative analysis methods were employed to evaluate questionnaires completed by students after the first event and before and after the second event. The results indicate the students’ were most engaged in learning about cultural traditions from the Tribal community, the “building and testing” portion of the engineering activity, and collaborative learning. After participating in the CR-EE activities students were more likely to perceive engineering as relevant to their Tribe and the degree of Tribal community involvement had a significant influence on the students' responses. Findings from this study provide the preliminary steps in understanding and validating theoretical strategies, which can support approaches for representing CR-EE in K12 classrooms that serve Native American students.

Chapter 3 Abstract

Paper Title: Identifying the Essential Properties of Biochar for Stormwater Treatment

The goal of this research was to provide a comprehensive evaluation of two different biochars for providing treatment of stormwater pollutants and to develop recommendations for the field application of a bioretention soil media (BSM) amended with biochar (BSM-Biochar mix). The pollutants include total suspended solids (TSS), dissolved Copper (Cu) and Zinc (Zn), Total Phosphorus (TP), Total Nitrogen (TN), Ammonia (NH3), and Nitrate-Nitrite (NO3-NO2). These goals were achieved by conducting an extensive literature search to identify a list of proposed Essential Properties. Specifically, those biochar physiochemical properties that indicate if a biochar is suitable for stormwater applications and may be useful in stormwater treatment design. Two biochars were selected for this study, one derived from wood (W) and the other from Kentucky blue grass feedstocks (KB), because they provide a range of Essential Properties to evaluate and compare. A laboratory study was conducted to evaluate the treatment performance of the biochars, which included: 1) jar testing and 2) flow through column testing. The results from the laboratory testing indicate: both biochars reduced TSS, Zn and Pb by >90%; the Cu removal efficiency was significantly higher for the W biochar (88% to 96%) compared to the KB biochar (47% to 78%); the NH3 removal efficiency (56% to 77%) was statistically insignificant between the biochars; the NO3-NO2 effluent concentration was only significantly higher than the influent for the columns with a larger quantity of biochar in which the NO3-NO2 was reduced by 3% to 12%; and the W biochar reduced (24.2%) significantly more TN compared to the KB biochar (14%). Neither biochar reduced TP. The KB biochar leached TP (-150% to -341%) compared to the W biochar in which the effluent concentration was statistically insignificant compared to the influent concentration. The results from this study may have been influenced by the stormwater influent hardness concentration (277 mg/L total and 227 mg/L dissolved) as well as hydrophobic characteristics observed by the biochars. Results from the laboratory testing were used to refine the list of Essential Properties, which include organic carbon, hydrogen to organic carbon ratio, cation exchange capacity, total surface area, calcium, pH, phosphorus, and nitrogen.

Chapter 4 Abstract

Paper Title: Development a Specification for Bioretention Soil Media Amended with Biochar for Stormwater Treatment

The goal of this research was to develop a specification for a bioretention soil media (BSM) amended with biochar (BSM-Biochar) that provides treatment of regional pollutants of concern (POC) and could be used by practitioners to design and construct bioretention best management practices (BMPs) in the field. The POCs evaluated in this study include total suspended solids (TSS), copper (Cu), zinc (Zn), total phosphorus (TP), total nitrogen (TN), ammonia (NH3), and nitrate-nitrite (NO3-NO2). This study is an extension of the previous study, where the key finding from the study detailed in Chapter 3 were combined with frequent citations from bioretention literature, and the Washington State Department of Ecology requirements for custom BSM to develop a draft BSM-Biochar specification. The two biochars selected for this study were developed from wood (W) and Kentucky blue grass (KB) source materials. A flow through column testing method was used to evaluate the treatment performance of the draft specifications using different BSM-Biochar mixes. The evaluation consisted of comparing the change in pollutant concentrations between influent and effluent samples as well as comparing changes in the pollutant concentrations in the BSM-Biochar mix from the top, middle, and base layer of the columns. The experimental design consisted of creating conditions that are representative of those expected in the field including using a natural stormwater solution to simulate rainfall conditions that are expected in eastern Washington where the study was conducted. The results from the water quality testing indicate: a reduction in TSS, Zn and Pb by >96% in all BSM-Biochar mixes; a reduction of Cu and NH3 concentration by >86%; NO3-NO2 leached from all the columns ranging from -53% to -48% and -48% to -33% for the columns that contained the KB and W biochars respectively. The columns that contained only the W biochar reduced TP concentrations by 21% to 26% compared the columns that contained only the KB biochar which leached TP by -77% to -110%. The trend in the treatment performances indicate that TP leaching from the KB columns declines over time while the efficacy of the W columns to reduce TP also declines over time. Results from the BSM-Biochar testing indicate that Ca and Mg cations are preferentially sorbed by the W biochar whereas Na cations are preferentially sorbed by the KB biochar. Overall, the majority of the heavy metals were retained in the top 6-inches of the BSM-Biochar mixes that contained both the W and KB biochar. The results of the column testing evaluation were used to confirm and refine the proposed specification and develop recommendations for field applications. A proposed BSM-Biochar specification is included in the Appendix.