CHAPTER 1

Introduction

1.1 Background

State departments of transportation (DOTs) are required under the federal Clean Water Act to comply with the National Pollutant Discharge Elimination System (NPDES) permitting program. The Construction General Permit (CGP) provides coverage under the NPDES program specifically for construction activities that disturb one or more acres of land. The CGP regulates stormwater discharges associated with construction sites to minimize pollution of water bodies and protect water quality. As part of the CGP requirements, permittees must develop and implement a Stormwater Pollution Prevention Plan (SWPPP) specific to their construction site. The SWPPP outlines the use of erosion and sediment control (ESC) measures and practices that will be implemented to prevent and control stormwater pollution.

State DOTs rely on manufactured ESC products to prevent soil loss and reduce sediment-laden stormwater pollution. These products can be installed temporarily or permanently, depending on the type of measure. Many of the measures commonly used for ESC contain plastics, since they are readily available, durable, and cost-effective. After installed in the environment, these plastic-based measures disintegrate into microplastics that are transported into surrounding water bodies through stormwater runoff. This emerging pollutant poses substantial environmental concerns due to its potential impacts on ecosystems, wildlife, and human health. In response, many state DOTs are reducing or eliminating plastic-based materials and products used in ESC measures. Consequently, this synthesis identifies the state of the practice for these efforts.

1.2 Synthesis Objective

The objective of this synthesis is to document current use of plastics in ESC practices across state DOTs and state DOT policies and plans to reduce or eliminate the use of plastics for ESC practices. This synthesis entails an investigation into the drivers and motivations behind the reduction or elimination of plastic-based ESC products included in a state DOT’s approved or qualified products list (APL/QPL). It also examines the strategies and programs adopted or developed by state DOTs to facilitate the reduction of plastic-based ESC products. The scope of this synthesis includes an investigation into the evaluation criteria employed by state DOTs for assessing ESC materials and products for inclusion in their APL/QPL. It also encompasses utilization of plastic-free alternatives successfully implemented on construction sites, as well as sourcing of materials and procurement methodologies for plastic-free materials and products. Additionally, it addresses challenges encountered in implementing plastic-free alternatives and the efforts made by state DOTs to develop educational and contractual content for dissemination among designers and contractors. This synthesis provides state DOTs with a summary of plastic-free ESC alternatives available within the industry and showcases successful efforts implemented by peer state DOTs to reduce or eliminate plastic-based ESC measures.

The scope of work for this synthesis includes documenting information on the following:

• Current DOT practices for plastic use in ESC (e.g., common temporary vs. permanent ESC products that contain plastics)
• Existing policies, guidelines, and specifications for reduction or elimination of plastics in ESC products
• State DOT strategies, plans, and goals to reduce or eliminate plastics from ESC practices
• State DOT efforts to recycle and reuse plastics in the current ESC practices
• State DOT use of non-plastic alternative ESC products (considering biodegradability, sustainability, and longevity)
• State DOT challenges and issues with the use of non-plastic materials in ESC practices

1.3 Synthesis Approach

To achieve the synthesis objectives, the project team conducted a literature review, developed and distributed a survey questionnaire to state DOTs, and performed six in-depth case examples. The literature review included a range of materials, such as peer-reviewed journal articles, research reports, government documents, conference papers and proceedings, gray literature, and websites. This review provided an initial understanding of the current state of the practice; findings are discussed in Chapter 2. The literature review, along with discussions with state DOTs and the synthesis panel, facilitated the development of the survey questionnaire.

The survey questionnaire was designed to identify the state of the practice regarding the use of sustainable materials for ESC practices among state DOTs. The survey began with a cover letter describing the purpose of the survey questionnaire, tips and guidelines for completing the survey, and key definitions to establish and align the terminology used within the survey. The survey gathered information regarding efforts for reducing plastic-based ESC practices used on construction sites. The survey was designed with skip logic to optimize data collection based on respondent answers. Skip logic is a feature that changes the question respondents see next based on how they answered a particular previous question. The survey was created and distributed using Alchemer’s survey management system, which provided an electronic platform for survey creation and response collection.

After the final draft of the survey questionnaire was approved by the synthesis panel, an email request with the survey link was distributed to state DOT stormwater professionals in all 50 states and the District of Columbia. A state DOT contact list was developed from several sources, including the Transportation Research Board’s Standing Committee on Hydrology, Hydraulics, and Stormwater (AKD50); the attendee roster of the 2022 Stormwater Practitioners Meeting held in Raleigh, North Carolina; and state DOT webpages. A PDF of the survey questionnaire was digitally provided to state DOT contacts as an email attachment. Contacts were asked to complete the survey or to forward the link to the appropriate state DOT individuals with knowledge of the subject matter. A copy of the survey questionnaire is provided in Appendix A.

A total of 42 state DOTs participated in the survey, yielding an 82% response rate. Figure 1.1 illustrates states that responded to the survey, as well as state DOTs that participated in the case example interviews. A summary of the survey responses is discussed in Chapter 3, with detailed responses provided in Appendix B.

After analyzing the survey responses, in-depth case examples were undertaken to supplement information regarding the utilization of sustainable materials for ESC practices. Candidates for follow-up interviews were chosen based on their willingness to participate in interviews (as indicated by their response to the final question in the survey) and their responses to specific survey inquiries. State DOTs demonstrating advancement toward sustainable usage of materials in ESC

practices were specifically invited to contribute additional insights. The six state DOTs invited to participate in case example interviews graciously accepted the invitation. The participating states were Colorado, Georgia, Minnesota, North Carolina, Vermont, and Washington. Details of the individual interviews are outlined in Chapter 4. The interview questions are provided in Appendix C. Chapter 5 provides a summary of the report and areas for future research.

At the end of this synthesis is a References list of all sources cited in the report, as well as a Glossary of terms and a list of abbreviations used in the report. Appendix A provides the complete survey questionnaire. Appendix B provides summaries of the survey responses. Appendix C provides the questionnaire used for case examples. Finally, Appendix D provides excerpts from select state DOT guidelines.