Study the Impacts of Caltrans Thermoplastic Stripe, Markings and Pavement Markers to Microplastic Pollution and Develop Potential Solutions

Details

• Creators:
  Asvapathanagul, Pitiporn ; Gedalanga, Philip
• Corporate Creators:
  California State University, Long Beach. Department of Civil Engineering and Construction Engineering Management ; California State University, Fullerton
• Corporate Contributors:
  California. Department of Transportation. Division of Research and Innovation
• Subject/TRT Terms:
  Best Practices Environmental Impacts Illuminated Traffic Signs Microplastic Pollution Microplastics Paint Plastics Pollution Road Markings Stormwater Stripping (Pavements) Thermoplastic Materials Thermoplastic Paint

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• Publication/ Report Number:
  CA25-4052
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States ; California
• Edition:
  Final Report
• Corporate Publisher:
  California. Department of Transportation. Department of Research, Innovation and System Information
• Abstract:
  Microplastic (MP) pollution has emerged as a critical environmental concern due to its pervasive presence and harmful impacts on human and environmental health. MPs, defined as plastic particles ranging from 1 nm to 5 mm, are problematic because of their ability to disperse widely across ecological habitats. Recent studies have illuminated roadways as a significant source of MPs, yet current best management practices for stormwater are not designed to address MP removal. This emphasizes the urgent need for solutions to mitigate MP pollution from transportation activities. Thermoplastic paint used in roadway markings and striping has been known as one source of MP pollution and the primary goal of this study was to quantify and characterize MP pollution from Caltrans facilities using samples of stormwater and roadway sweeping materials. The first street sweeping samples were taken on November 14, 2023, and stormwater samples were collected on February 19, 2024, and March 23, 2024, after the first local rain events. Each sample was deposited into a MPs treatment system’s chamber and then processed in a vortex separator. The results revealed that high number of MP counts were observed in the 45 to 1,000 μm size, and small particles (< 300 μm) were more mobile during storm events. Sweeping samples (11 classes) exhibited greater polymer diversity than stormwater samples (5-6 classes), and a strong correlation (r = 0.79, p < 0.05) between MPs in sweeping debris and March stormwater confirmed roadway-origin MPs were mobilized during rainfall. MP concentrations in stormwater varied from 83 to 157 MPs/L, which may be influenced by storm patterns, cleaning schedules, and sampling conditions. MPs of concern included polyolefins (polyalkenes), such as polyethylene (PE) and polypropylene (PP), as well as ‘other plastics’, which were present in large fractions in all environmental samples. The vortex separator achieved a 69.7% MP removal efficiency at 12 gpm, a system capacity, which was close to the MP target removal of 70%. However, the MPs removal efficiency dropped notably for particles in the 45 – 100 μm range, 14.0% ± 12.7%. A multivariable regression analysis for predicting MP removal by vortex separator identified a particle size parameter as the most significant factor influencing MP removal. Also, the settling compartment demonstrated high solids removal, not MP removal, percentage (> 99%) for particles > 100 μm. The solid removal performance of settling compartment declined at higher flow rates and for smaller particles.
• Format:
  PDF
• Funding:
  65A1025
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:48828ac236bc9633bd105395c2676cf225973343a443ec4072347a657363994ec82451c07b311c2888730881aef29c85605d6ea9459234bdff6958dd1b835cb9
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/87013/dot_87013_DS1.pdf
• File Type:
  [PDF - 9.50 MB ]