Date of Award

Spring 5-10-2022

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science in Civil Engineering (MSCE)

Department

Civil Engineering

Advisor

Shaleen Jain

Second Committee Member

Jonathan D. Rubin

Third Committee Member

Mohammadali Shirazi

Additional Committee Members

Per Gårder

Abstract

The research is inspired by the past and current patterns of road salt use, changing weather patterns, and management strategies in Maine. The historical road salt application has led to long-term impacts on the environment pressing the need for strategic use of road salt. Winter Severity Indices (WSIs) find their application in the field by aiding in interpreting weather forecasts and planning for strategic salt application. This study uses existing indices: Accumulated Winter Season Severity Index (AWSSI), Strategic Highway Research Program (SHRP) index, Illinois Salt days index, and Accumulated Freezing Degree Days to quantify long-term changes in winter weather conditions. Statistical models based on Principal Component Analysis, Quantile, and quasi-Poisson regression provide estimates of trends, interdependence between weather variables and salt use, derivation of weather indices model with high salience towards the use of road salt. Results show the existing index and changing baselines linked to salt application practice explain most of the variability (R2 greater than 80%) in salt usage from 1991 to 2020. The leading components of WSIs parse Maine’s weather variability into short-term and long-term patterns showing increasing severity, in general, along coastal regions. The research also investigates the prevalence of rising chlorides in groundwater in Maine. The impact assessment is based on the water quality data set analysis to get estimates of the local risk of well contamination due to chlorides. Qualitative analysis of chlorides in well and appropriate co-variates representing the proximate environment are also presented. We find general patterns of increasing chlorides with decreasing distance to high-priority roads. In addition, the local risk of wells for chloride contamination and arsenic mobilization provide substantial grounds for further study. The results from this study will help state and local road maintenance agencies understand the regional disparity in winter severity and implement informed road salt application decisions in potential contamination zones.

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