Rehabilitation of Culverts and Buried Storm Drain Pipes (2022)

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6 This chapter documents the findings from the literature review. Relevant topics that are addressed in this chapter include major factors affecting the selection of culvert rehabilitation methodologies; commonly used culvert rehabilitation methods and best practices reported in the literature; and standards and guidance documents developed by different state DOTs, other agencies, and researchers. Repair and rehabilitation best practices and guidance documents prepared by several state DOTs are presented in Sections 2.1 and 2.2. Additional publications (FHWA, 1995; Wyant, 2002; Allouche, 2010; and Ward, 2018) present comprehensive discussions of various culvert rehabilitation methods. For example, the Final Draft Report for NCHRP Project 14-19 includes a detailed literature review relevant to this study with sources on topics such as types of cul- vert defects and deterioration, hydraulic capacity of culverts, inspection methods, and different methods of rehabilitation design (Allouche, 2010). 2.1 Factors Affecting the Selection of Culvert Rehabilitation Method Selection of an appropriate culvert rehabilitation methodology is influenced by many different factors, including the current condition of the deficient culvert and limitations related to con- struction. In this study, the importance of the following factors was investigated: environmental factors, including humidity and temperature variations; hydraulics; materials; site geometry; site access for rehabilitation; impacts on the traveling public; ability to perform rehabilitation work in-house; and expected service life and life-cycle costs. These factors were also discussed in most of the rehabilitation manuals and best practices documents developed by several state DOTs. The Delaware DOT (2021) developed flow charts to help with the decision process in the selection of an appropriate rehabilitation method on the basis of the type and extent of the defect or deterioration observed during culvert inspection. For example, depending on the length and width of the observed longitudinal or circumferential crack in a reinforced concrete pipe (RCP), guidance and the following options are provided: no repair, sealing, pipe stabilization, full struc- tural repair, or removal and replacement of the pipe. See Figure 4-1 in the Delaware DOT case example developed for this synthesis report. The Minnesota DOT presents several tables outlining observations of key culvert deficiencies and likely causes, and factors causing culvert deterioration (Wagener and Leagjeld, 2014). As part of the Minnesota DOT’s culvert and storm drain management system, called HydInfra, flow- charts are prepared to identify potential repair or rehabilitation methods by considering the important factors examined in this report. The Delaware DOT (2021), Maine DOT (Hartley, C H A P T E R 2 Literature Review

Literature Review 7   2014), and Wisconsin DOT (2018) provide similar flowcharts and tables that include potential factors causing culvert deterioration. Design Information Bulletin 83-04 (Caltrans, 2014) discusses several factors affecting the ser- vice life of culverts and rehabilitation methods. Hydrogen ion (pH) concentration, soil resis- tivity, and the chloride and sulfate concentration of the surrounding soil and water are listed as potential causes of corrosion attack and associated deterioration in both concrete and metal culverts. Therefore, in selection of the appropriate repair and rehabilitation materials, these factors and the material characteristics of the culvert must be considered. Abrasion, which is another factor listed by Caltrans (2014), is the wearing of pipe material by water carrying sands, gravels, and rocks. Hydraulics (e.g., stream flow velocities and frequency of flow events) and particle size in water can make a significant impact on abrasion and culvert deterioration. General site characteristics will be a factor due to the size and shape of the materials in the streambed and the average stream slopes. Caltrans (2014) discusses the resistance of various culvert and rehabilitation materials against abrasion and other factors such as pH level. 2.2 Culvert Rehabilitation Specifications and Guidelines In addition to culvert rehabilitation specifications and provisions developed by various trans- portation agencies, several best practices and guidance documents are available. Best practices and rehabilitation manuals developed by Caltrans (2014), the Delaware DOT (2021), the Maine DOT (Hartley, 2014), the Minnesota DOT (Wagener and Leagjeld, 2014), and the Wisconsin DOT (2018) are valuable resources. The descriptions and summaries of different culvert rehabili- tation methods provided in Section 2.3 are based on these and similar documents, such as the reports by FHWA (1995), Wyant (2002), Allouche (2010), Hollingshead and Tullis (2009), and Ward (2018). There are several ASTM standard practices and specifications for culvert rehabilitation, which are referenced in different state DOT standard specifications. For example, ASTM C1131 (2020) provides guidance for least-cost or life-cycle analysis of concrete culverts and drainage pipes. Similarly, ASTM A930-09 (2020) presents life-cycle cost analysis of CMP used for culverts, storm sewers, and other buried conduits. Life-cycle cost analysis of plastic pipes is covered in ASTM F1675-13 (2017). ASTM standards typically describe installation procedures and provide requirements for materials, test methods, and inspection. Specifications are provided for different rehabilitation methods, including • Application of coatings, pavings, and linings in CMPs (ASTM A849, 2021); • Mechanical trenchless steel sleeves (ASTM F3110, 2018); • Grout-in-place lining (ASTM F2984, 2019), as shown in Figure 2-1; • CIPP and inversion and curing of a resin-impregnated tube (ASTM F1216, 2016); and • Concrete pavements and linings in CMPs (ASTM A979, 2019). 2.3 Culvert Repair and Rehabilitation Methods This section provides a brief overview of repair and rehabilitation methods for culverts and storm drain pipes. The organization follows the order used in Question 6 of the questionnaire included in Appendix A: (1) local repair and joint repair methods, (2) invert paving or invert lining methods, and (3) general system rehabilitation methods.

8 Rehabilitation of Culverts and Buried Storm Drain Pipes 2.3.1 Local Repair, Coating, Grouting, and Sealing When the deficiency is local (e.g., due to spalling in concrete walls, corrosion or deterioration in joint regions, or corrosion of metal culverts), local repair, spot patch, grouting, sealing, or sim- ilar structural or nonstructural repair methods can be used. Nonstructural repairs can be part of maintenance programs to fix relatively minor issues and prevent potential future structural damage or deterioration. Nonstructural repairs can include local injection of epoxy adhesive or flexible crack fillers in concrete walls; chemical grouting with gels and foams (Figure 2-2); and recoating or repainting of metal culverts. Local structural deficiencies may include or be caused by joint separation, misalignment, or continued infiltration or exfiltration. Internal joint sealing systems, including rubber membrane or backing plates, cementitious grouting, internal joint sealing with steel sleeves or expansion rings (Figure 2-2), and plates or internal bands combined with grout or gaskets can be effective in fixing the problem before the damage spreads and becomes a system-level problem. 2.3.2 Invert Paving or Invert Lining Typically, corrosion and abrasion in precast concrete and metal culverts cause deterioration of the inverts. Deteriorated inverts of precast concrete culverts can be paved with concrete. Source: ASTM F2984, 2019. Reprinted with permission. Figure 2-1. Grout-in-place liner rehabilitation method. Source: Caltrans, 2014. Figure 2-2. Internal chemical-grouted joint (left) and internal joint sealing system (middle and right).

Literature Review 9   Abrasion and corrosion in inverts of CMP culverts may lead to (1) joint defects, (2) deteriora- tion, (3) shape distortion, and (4) soil migration (Caltrans, 2014). Depending on the level of deficiency, local joint repairs or other repairs to enhance durability (e.g., recoating, grouting, or sealing) may be performed as described above. Invert paving with reinforced or unreinforced concrete is probably one of the most effective ways to rehabilitate corroded and severely dete- riorated inverts of CMP using different materials, as shown in Figure 2-3. Masada (2017) conducted a comprehensive study including field testing of existing culverts, testing of laboratory specimens, and analytical modeling of culverts rehabilitated with concrete invert paving. The need for and required amount of reinforcement in concrete pavement were also investigated. Similarly, Tetreault et al. (2018) tested a corroded and then a concrete-paved elliptical corrugated steel culvert in the laboratory and demonstrated the improvement in the structural performance. Concrete or metal culvert inverts can be armored with steel plates by using different design or anchoring approaches. Figure 2-4 shows a procedure included in FHWA’s Culvert Repair Prac- tices Manual (1995) in which the anchorage between the cleaned culvert invert and steel plate is provided by the composite action provided by the steel studs embedded in concrete. The reha- bilitation installation shown in Figure 2-4 was applied in a culvert in Cullman County, Alabama. 2.3.3 General Rehabilitation Methods Eight general rehabilitation methods were included in the survey. Best practices and reha- bilitation manuals developed by Caltrans (2014), the Delaware DOT (2021), the Maine DOT (Hartley, 2014), the Minnesota DOT (Wagener and Leagjeld, 2014), and the Wisconsin DOT (2018) present examples and descriptions of these methods. A summary of the methods is pro- vided here. 2.3.3.1 Sandblasting and Recoating or Painting Deteriorated concrete, corrosion, or coating damage can be removed by using sandblasting or high-pressure water prior to recoating (e.g., with silanes), painting, or application of other Source: Caltrans, 2014. Figure 2-3. Concrete invert paving of corrugated metal pipe culvert.

10 Rehabilitation of Culverts and Buried Storm Drain Pipes protective systems (e.g., cathodic protection) on the walls or invert of the culvert. For example, Section 502 of the Maine DOT’s Standard Specifications (Maine DOT, 2020) requires sand- blasting of metal surfaces prior to application of structural concrete invert lining. 2.3.3.2 Shotcrete Cement mortar lining or sprayed mortar applications are commonly used for repair or reha- bilitation. Although shotcrete can be used in large culverts, according to Caltrans (2014), it is a good alternative for lining corroded and/or abraded corrugated steel pipes of smaller diameter after pressure grouting any voids below the pipe as an effective invert lining method. 2.3.3.3 Cured-in-Place Pipe CIPP is installed by feeding a sleeve soaked in thermosetting resin through the host pipe, expanding it, and then heating to cure the resin. CIPP can be used in noncircular culverts; it eliminates joints/seams and bridges all joints on the interior surface of the pipe and eliminates the need for grouting. CIPP is frequently used by the Oregon DOT, and, as a result, CIPP design, material, and construction requirements are included in Oregon’s Standard Specifications for Construction (Oregon DOT, 2021). Potential release of organic chemicals during the CIPP reha- bilitation process was investigated by NASSCO (Najafi et al., 2018). 2.3.3.4 Spray-Applied Structural Lining Centrifugally cast and spray-applied lining systems and spray-on treatments typically provide a continuous lining within the existing pipe. Pressurized spraying of concrete, concrete sealers, silicone, polyurethane, or similar materials onto the culvert wall surface aim to increase struc- tural capacity or to improve durability, water tightness, and corrosion resistance. Moore (2019) presented design equations for sprayed cementitious liners within corrugated steel pipes on the basis of full-scale experiments. Four different alternative design procedures are presented, depending on the consideration of the contribution of the deteriorated corrugated steel pipe to the liner–host pipe soil system (e.g., by considering the liner alone or the full composite action of the liner and existing pipe). A recently completed comprehensive experimental and computational study concluded that both polymeric and cementitious spray-applied liners were able to increase the structural capacity Source: FHWA, 1995 (left), and Caltrans, 2014 (right). Figure 2-4. Typical armor plate section (left) and installed steel plate invert (right).

Literature Review 11   of fully invert deteriorated CMPs and restore the ring compression resistance of the rehabilitated pipes (Najafi et al., 2021). Since the polymeric lining did not crack at the invert cut location, even at the ultimate loading stage, the polymeric liner alone was structurally capable of performing as a new pipe inside the host pipe (i.e., pipe in pipe) and could solely resist the applied load. On the basis of tests of 15 large-span CMP specimens, field investigation, and finite element simulations, the study proposed structural design equations for culverts rehabilitated with spray-applied liners (Najafi et al., 2021). 2.3.3.5 Sliplining and Other Trenchless Techniques for Rehabilitation Sliplining is a common method for extending the service life of a culvert by installing a new internal pipe of smaller diameter inside the existing culvert. Although the hydraulic capacity may be reduced, sliplining can be advantageous and faster, especially when it is difficult to imple- ment invert paving or other methods. A grouting plan that considers strength, flow rate, setting and other material properties, site-specific conditions, and construction requirements is needed. Tetreault et al. (2020) investigated the effect of grout choice on the performance of corrugated steel pipes rehabilitated with high-density polyethylene (HDPE) slipliners, including low-density (i.e., low-modulus and low-strength) grout and high-density grout. They found that the pipe sliplined with low-density grout behaved more flexibly, while the pipe sliplined with high-density grout behaved like a rigid pipe under ultimate load tests. 2.3.3.6 Stabilization of Surrounding Backfill or Filling Voids in Outside Envelope In order to reestablish the soil–pipe interaction and stop or prevent potential distortion, the voids outside the culvert may need to be adequately stabilized, possibly through pressure-grouting operations or controlled injection. 2.3.3.7 Replacement of Existing Culvert or Pipe Through Trenchless Installation Due to heavy traffic, the site conditions and factors may necessitate trenchless installation, which may include pipe jacking, usually accompanied by a boring operation; microtunneling; horizontal directional drilling; pipe swallowing or pipe crushing; auger boring; pipe ramming; pipe bursting; pipe splitting; or similar methods. NCHRP Synthesis 519: The Renewal of Storm- water Systems Using Trenchless Technologies (Ward, 2018) summarizes trenchless technologies for replacement and rehabilitation of culverts, including some of the methods investigated in this report. 2.3.3.8 End Treatment Repair and rehabilitation of deficient endwalls or wingwalls may involve installation of new walls or slope protection elements at the ends of the culvert or pipe. FHWA (1995) provides an application procedure for repair of basically sound endwalls and wingwalls except for a deterio- rated or broken section. If the wingwall is in upright position and not tipped, then the proce- dure shown in Figure 2-5 can be applied. FHWA (1995) also presents procedures for repairing severely deteriorated or collapsed wingwalls and endwalls and for concrete jacket repairs for wingwalls and endwalls. Wisconsin’s Facilities Development Manual states that in reinforced concrete box structures, the bevel-edged inlet is the most economical method of improving the capacity of a conven- tional culvert (Wisconsin DOT, 1997). The addition of bevels to a conventional culvert with a square-edged inlet can increase the culvert’s capacity by 5% to 20%. The Facilities Development Manual also states that side-tapered inlet and slope-tapered inlet can increase the flow capacity by 25% to 100%, as compared with a conventional culvert with a square-edged inlet.

12 Rehabilitation of Culverts and Buried Storm Drain Pipes Source: FHWA, 1995. Figure 2-5. Repair of basically sound wingwall at culvert ends.

Literature Review 13   2.4 Brief Summary of Literature Review Findings In addition to guidance and review documents developed by different state DOTs, com- prehensive culvert rehabilitation information is available in several research reports (FHWA, 1995; Wyant, 2002; Allouche, 2010). There are also several ASTM standards (Section 2.2), which are typically adopted or cited in state DOT specifications. The California, Delaware, Maine, Minnesota, and Wisconsin DOTs have developed best practice and guidance documents for inspection, evaluation, and rehabilitation of culverts. As revealed by these guidance documents, in many cases, practical applications by the state DOTs appear to be completed without available research data, although individual researchers investigated different rehabilitation methods. For example, Tetreault et al. (2020) investigated the effect of grout on sliplining of corrugated metal host pipe with HDPE pipe. Najafi et al. (2021) performed one of the most comprehensive studies on a rehabilitation method, specifically, on spray-applied structural linings. Although significant research is avail- able [e.g., by Moore (2019) on spray-applied linings or Masada (2017) and Tetreault et al. (2018) on concrete paving of deteriorated metal culvert inverts], more comprehensive research studies, such as that of Najafi et al. (2021), are needed to investigate different rehabilitation methods. The 2021 report by Najafi et al. includes field data collection, laboratory experiments, computational models and finite element simulations, development of structural design equations, cost com- parisons, and development of performance construction specifications. Such research results are likely to be implemented and incorporated into design guidance documents or specifications of the state DOTs.