The Renewal of Stormwater Systems Using Trenchless Technologies (2018)

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3 This chapter provides (1) the definition of trenchless renewal; (2) background information on the objectives of the synthesis; (3) an overview of the study methodology including the study questionnaire, the literature review, and the interviews; and (4) the organization of the synthesis. What Is Trenchless Renewal of Stormwater Systems? Trenchless renewal includes a wide variety of methods used to upgrade, rehabilitate, repair, and renovate the performance and increase the design life of existing stormwater facilities. This syn- thesis focuses primarily on the trenchless renewal of culverts typically ranging in diameter from 12 in. to over 12 ft with both circular and noncircular cross-sections. While most aging culverts consist of either corrugated metal or concrete pipe, some of the renewal methods discussed in this synthesis are also applicable to other pipe types. These methods can be broadly grouped into the following categories: CIPP, SL, MSL, ILR, SIPP, and CFP (see “Definitions” section in Chapter 2). While the application, design, and construction of these methods are varied, the underlying commonalities for the trenchless renewal methods are as follows: • They occur along or at the existing stormwater facility location. • They minimize negative surface disruption and impacts. Trenchless installation methods are not covered in this synthesis. Trenchless installation methods, such as pipe ramming, auger boring, horizontal directional drilling, and so forth, do not necessarily rely on the presence of an existing facility and are therefore not considered trenchless renewal. Refer to NCHRP Synthesis 242 (Iseley and Gokhale 1997) for more informa- tion on trenchless installation methods. Background Highway and transportation system stakeholders recognize the overwhelming need for effective technologies in both the structural and functional renewal of stormwater facilities. Many existing facilities are reaching or exceeding their useful service. Facility owners now more than ever have a need to minimize negative impacts and to maximize the cost benefits. For some stakeholders, trenchless technologies are replacing traditional techniques to accomplish the renewal of culverts, storm sewers, and drainage structures. The selection of the trenchless renewal method depends on a variety of technical factors that are generally understood by experienced designers. However, many transportation system orga- nizations have limited experience with multiple methods. This synthesis provides a summary of C H A P T E R 1 Introduction

4 The Renewal of Stormwater Systems Using Trenchless Technologies the methods and generally accepted applicability. A bibliography of other existing publications is provided for the inquisitive reader. This synthesis has four objectives: 1. Provide an understanding of the successful practices and associated limiting factors for using trenchless technologies to renew stormwater facilities. 2. Characterize the decision criteria used by facility owners when choosing a renewal method. 3. Characterize how state DOTs and local agencies are using trenchless technologies. 4. Summarize new, emergent, and underutilized methods and technologies that might be used in highway applications and suggest further research needs. Study Methodology The methods used to gather the information for this study consisted of the following: • A questionnaire sent to the 50 state DOTs; • Literature search, review, and synthesis; and • Interviews with individual DOTs, representatives of municipalities, special districts, and private sector firms. Study Questionnaire The questionnaire consists of primarily closed-end questions with selected opportunities for the respondents to provide clarifying details. The questionnaire is included in Appendix A, which can be found on the TRB website (www.trb.org) by searching for “NCHRP Synthesis 519.” For respondents with experience using trenchless renewal, the questions are organized into the following seven sections: 1. Methods used and satisfaction. This section asks questions regarding how trenchless renewal methods are used, the relative frequency of use, and satisfaction with the methods used. This also includes characterizing whether renewal is used to temporarily defer replacement with a new system, the frequency of use for non-structural defect renewal, and the frequency of manhole and vault renewal. 2. Defects mitigated and satisfaction. This section asks questions to identify the relative fre- quency with which various defect types are addressed using trenchless methods. This includes a relative satisfaction rating associated with the mitigation. 3. Case studies and available cost data. This section asks questions to identify which respondents have shareable case history and cost data. 4. Decision criteria. This section asks questions to identify if standardized decision criteria are used to select the trenchless renewal method. Where standardized criteria are not used, the respondent is asked to describe the process used. 5. Reasons for not using trenchless renewal when technically feasible. This section asks questions to determine common reasons for not using trenchless renewal when trenchless renewal is technically feasible. A list of potential reasons is provided and the respondents are asked to select their common reasons and are given the opportunity to write in additional reasons. 6. Reasons for using trenchless renewal when technically feasible. This section asks questions to determine common reasons for using trenchless renewal. The respondents are asked to provide the top five reasons their organization selected trenchless renewal. 7. Project cost exceedance and claims. This section asks questions to identify the relative frequency and magnitude of project cost exceedance on trenchless renewal projects. This includes an open-ended question to identify the typical reasons.

Introduction 5 An eighth section is provided for respondents without trenchless renewal experience. This section asks questions to determine what information might help them consider using trenchless renewal in the future. A list of reasons for not using trenchless renewal is provided. The respon- dents ranked their top five reasons for not using trenchless renewal. Literature Review The literature review consisted of three main components: references identified in the original project scope, an electronic database search, and an Internet search. The reviewed and referenced publications identified in the literature search are included in the References section of this report. A list of background materials not specifically cited in the text is included in the Bibliography at the end of this report. To focus on current practice and emergent methods, the electronic database search focused on publications from January 2010 through January 2017. The following curated and subject- specialized databases were searched using ProQuest Dialog. These databases contain published and mostly peer-reviewed literature indexed by professionals. • The Aqualine database indexes trade, technical, and scientific literature concerning all aspects of water resources drawn from a source list of approximately 300 journals as well as from conference proceedings, scientific reports, books, and theses. • Civil Engineering Abstracts indexes literature from architecture, structural design, and con- struction engineering to environmental, seismic engineering, and forensics from more than 4,000 sources including periodicals, conference papers, trade journals, magazines, books, patents, and technical reports. • Ei Compendex indexes engineering and technology literature in 190 disciplines including civil, environmental, and geological engineering. The literature is drawn from 6,500 primary sources including journals, transactions, reports, and special publications of engineering societies, scientific and technical associations, government agencies, universities, laboratories, research institutions, and industrial organizations; proceedings of conferences, symposia, and colloquia; monographs; standards; and seminars and reports. • Gale Group PROMT is a multiple-industry database providing broad, international coverage of more than 60 manufacturing and services industries including engineering, manufacturing, and environmental services. • Inspec is a bibliographic database with specialized indexing of physics and engineering literature from journals and serials, conference papers and proceedings, books and book chapters, and technical reports. Some standards, dissertations, and a small number of UK and U.S. patents are included. The database is produced by the Institution of Engineering and Technology. • TRID is an integrated database that combines the records from Transportation Research Board’s Transportation Research Information Services Database and the Organization for Economic Co-operation and Development’s Joint Transport Research Centre’s International Transport Research Documentation Database. TRID provides access to more than one million records of transportation research worldwide. A keyword search of the Internet was also performed to supplement the curated and subject- specialized database search. Interviews Information obtained from the interviews is presented in Chapter 3. The information from the interviews was used to supplement the literature search and questionnaire results.

6 The Renewal of Stormwater Systems Using Trenchless Technologies Organization of Synthesis This synthesis is organized into four chapters and two appendices. • Chapter 1 provides background for the synthesis topic and overview of the study methodology, including the survey questionnaire. • Chapter 2 provides an overview of the trenchless methods included in this synthesis, a summary of the advantages and challenges of the methods, and case studies. Emergent and underutilized technologies that might be applicable for trenchless renewal of stormwater systems are also included. • Chapter 3 summarizes the current practice and experience regarding the use of the trenchless renewal methods. • Chapter 4 summarizes the synthesis findings and identifies further research needs. • Appendix A includes the survey questionnaire. This appendix can be found on the TRB website (www.trb.org) by searching for “NCHRP Synthesis 519.” • Appendix B provides the respondents’ names and addresses. This appendix can be found on the TRB website (www.trb.org) by searching for “NCHRP Synthesis 519.” Chapter Summary Trenchless renewal is defined as methods used to upgrade, rehabilitate, repair, and renovate the performance and increase the design life of existing stormwater facilities (primarily culverts). The objectives of this synthesis are fourfold. First, describe the successful practices and associ- ated limiting factors for the various renewal methods. Second, characterize the decision criteria used by DOTs for choosing a renewal method. Third, characterize how DOTs and local agencies are using trenchless technologies. Fourth, summarize new, emergent, and underutilized meth- ods and technologies and suggest further research needs. The methods used to gather the information for this synthesis included a questionnaire, literature search, and interviews.