Trenchless Methods Research Articles

How does trenchless technology make pipeline construction greener? A comprehensive carbon footprint and energy consumption analysis

Pipelines are the primary means of transporting energy or resources, such as oil, natural gas, or water. Nowadays, with the increasing demand for resources, the construction of pipelines is also increasing. Under the context of promoting green production, the open-cut method has been unable to meet the requirements of environmental protection. Therefore, trenchless technology has become an alternative to pipeline construction, which has the characteristics of fast construction speed and low carbon footprint. This paper briefly introduces a variety of typical trenchless installation and renewal methods. Based on the relevant theory of carbon footprint calculation during construction, the energy consumption and carbon footprint from the open-cut method and the trenchless construction methods under the same conditions are compared. Moreover, the sensitivity of different construction methods to different factors is analyzed. The main conclusions are drawn: (1) In most cases, the cured-in-place pipe method has less energy consumption and carbon footprint than other pipeline repair methods and is less affected by various design factors. (2) Various trenchless technologies have reduced construction energy consumption and carbon footprint to varying degrees relative to the open-cut method. (3) When the construction length is short or the depth is very shallow, the energy consumption and carbon footprint of the trenchless method may be higher than the open-cut method.

Environmental Impacts of Conventional Open-Cut Pipeline Installation and Trenchless Technology Methods: State-of-the-Art Review

With growing concerns about global warming and greenhouse gases (GHG), there is an urgent need to quantify and reduce the environmental impact (EI) of pipeline installation (PI). The most common and popular criterion used to describe sustainability efforts from the environmental perspective is the concept of carbon footprint (CF). A CF is the total set of GHG emissions caused by an organization, event, or product. It is expressed in terms of the amount of carbon dioxide (CO2), or its equivalent of other emitted GHGs. The open-cut pipeline installation (OCPI) method involves digging a trench along the length of the proposed pipeline, placing the pipe in the trench on suitable bedding materials and then embedding and backfilling. The trenchless method (TM) involves methods, materials, and equipment capable of the installation of new, replacing old, or renewing existing pipelines with minimal disruption to surface traffic, business, and subsurface. Choosing an appropriate low-carbon emission method to install or renew pipelines is an important task and may consider environmental concerns due to several energy-consuming activities, including material manufacturing, transportation, and installation. Because essentially, every PI and renewal project impacts the environment, it is of utmost importance for the pipeline project owner and the design engineer to evaluate this impact and take necessary actions to minimize any negative consequence. The objective of this paper is to present a literature review on progress acquired over the years in understanding GHG emissions from OCPI and TMs and to discuss a framework for CF estimation. Published papers were identified that reported GHG emissions and CF of the open-cut (OC) method and TM over a period from 1989 through 2019. This literature review suggests that for most of these PI and renewal projects, the material production phase consumes a large amount of energy and is a major contributor of GHG emissions. Higher GHG emissions in the OCPI method is a result of longer project durations and more equipment requirements compared with TMs where a smaller footprint or excavation area is used. Early phases of project planning should include appropriate ecological decisions consistent with the life cycle cost (LCC) and CF considerations. Pipe material and outside diameter should be considered during the installation phase by OC and TM to allow a detailed evaluation and comparison of their sustainability impacts. Incorporation of additional factors, such as cost and duration of the project, into the environmental analysis is recommended for the development of a comprehensive decision-making model to select the most environment-friendly PI method.

Issue of annular space filling requirement in engineering networks renovation justification

The main research aim was to determine the feasibility of filling the annular space with cement or other mortar during the renovation of dilapidated drainage networks with one of the common trenchless methods, i.e. by pulling pipes of smaller diameter through them (stalks from a roll). If polymer pipes are used for pulling, justification for the use of filling is necessary, due to their specific properties, which can affect the pipeline system strength and hydraulic performance. The article discusses the need for the pipelines annular space cementation during trenchless repairs.

Investigating the use of no-dig technologies for underground utilities in developing countries

Major cities in most of the developing countries are becoming increasingly crowded. Conventional open-trench methods are expensive and lead to traffic disruption. The domestic government is looking at alternative approaches to install and rehabilitate aging underground utilities. The purpose of this study is to investigate the level of awareness and utilization of no-dig (i.e., trenchless technology) methods, the potential of their future growth, and their impact on social costs in a developing country. A survey was first conducted to investigate the use of trenchless technology methods in new construction and rehabilitation of infrastructure projects. The pertaining impact on social costs was then examined. Survey data were analyzed, and the potential of future growth of using trenchless technology methods was investigated. It has been found that “horizontal directional drilling” is the prevalent trenchless method used, while “robotic spot repair” is the least utilized one among all the methods used for new construction or rehabilitation of underground utilities. The results also revealed that using trenchless construction has a maximum impact on the “travel/traffic delay” type of social costs. The “horizontal directional drilling” method has the highest potential of future growth in new construction, while the “lining of pipe” was ranked first among rehabilitation methods. The data analysis results have also revealed that a critical social implication of using trenchless construction methods is their limited disruptions to the society when installing or rehabilitating underground utilities. Such social disruptions include road closures, traffic delays, and detours resulting in noise and loss of access to homes/businesses.

Challenges of constructing a twin 5.2 km long undersea fuel pipelines by HDD method

ABSTRACTDue to the expansion of the existing Hong Kong International Airport, known as the Three Runway System, two new 500 mm diameter, 5.2 km long aviation fuel pipelines were proposed to be built through bedrock undersea to replace the two-existing submarine aviation fuel pipelines running between the Western Quay of the Airport and the offshore Aviation Fuel Receiving Facility (AFRF) at Sha Chau. Having considered the site constraints with the expansion works for the new airport island, and minimising the disturbance of marine environments and ecology, a trenchless method using horizontal direction drilling (HDD) technique that is a cost-effective and environmental-friendly solution was adopted to complete these two aviation fuel pipelines' installation. Numerous challenges were encountered for constructing this 5.2 km long subsea pipeline using HDD method that is the longest record in the world at the time. Although the mission of the project seemed impossible, the challenge still can be defeated by incorporating technology, advanced equipment, knowledge and good practice of project planning.

A Phase I Cultural Resources Survey of the Orbit Pipeline Project Jefferson, Liberty, and Chambers Counties, Texas

A Phase I Cultural Resources Survey of the Orbit Pipeline Project Jefferson, Liberty, and Chambers Counties, Texas

INNOVATIVE DEVELOPMENT OF TECHNOLOGIES FOR THE CONSTRUCTION OF ANTIFILTRATION FACILITIES

Relevance of research. In the course of the operation of irrigation systems, there is a need to protect the hydraulic structures and the adjacent territories from filtration, which should be considered as a separate type of harmful effects of water. Filtration of water from canals and ponds leads to secondary flooding, salinization and waterlogging. Filtration of water at earth dams under certain conditions leads to the destruction of dams and the creation of emergency zones in the surrounding territories. In today's conditions of reforming the Ukrainian economy, it is particularly important to use technically reliable, environmentally sound and economically feasible filtration protection facilities in hydrotechnical construction.
 The purpose of the study is to identify priority areas for innovative development of technologies for the construction of anti-filtration facilities and to outline the main achievements of the Institute of WPLR NAAS in solving the problem of protection against filtration in hydraulic engineering in the past.
 Research methodology. The study used the method of generalization and system analysis of structural and technological solutions of complex systems.
 Research results. Priority areas of the solving one of the urgent problems of hydrotechnical construction - problems of protection against filtration are grounded in the article. It is noted that over the past 60 years, the technologies of construction of anti-filtration structures have developed significantly. The technological level of construction of anti-filtration structures was increased by qualitative improvement and quantitative increase of anti-filtration materials, constructive solutions for anti-filtration structures, technological solutions for construction of anti-filtration structures, structural solutions of the means of mechanical laying anti-filtration materials. Based on the results of the system analysis, the hierarchical subordination of structural and technological solutions for the construction of anti-filtration structures was determined. Based on the results of functional-cost analysis of structural and technological solutions, analytical dependencies were established to determine the priority areas of innovative development of technologies for construction of anti-filtration structures. The new most significant structural and technological solutions and scientific and technical developments in the construction of anti-filtration structures, which were created at the Institute of Water Problems and Reclamation of the NAAS in the past, are presented.
 Over the past 60 years the Institute has developed the following technical and technological solutions in the area of protection against harmful effects of filtration: trenchless method of laying vertical screens made of polymer film; construction of anti-filtration structures using trenchless method of laying vertical screens; construction of earth dams in a tiered way; construction of concrete film screens, soil film screens, anti-filtration hangers with the use of polymer film folded into the package; improved traditional technology of construction by the method of anti-filtration curtains made of polymer film by the wall-to-soil method. The Institute has also developed the recommendations for determining the technological standards of water losses in irrigation canals in terms of reducing the useful flow of water in them. It is established that the efficiency of the canals is not technical, but technical and operational characteristics of irrigation canals. A formula for adjusting the design efficiency of irrigation canals has been developed depending on the actual water flow in the irrigation network.

Fem stress analysis of a barrel reamer

Abstract Horizontal Directional Drilling (HDD) is a method of installing underground pipelines, cables and service conduit through trenchless methods. The tools and techniques used in the HDD process are an outgrowth of the oil well drilling industry, too. Installation of a pipeline by HDD is a three stages process. The first stage consists of directionally drilling a small diameter pilot hole along a designed directional path. Drilling fluid is pumped through the drill pipe to the drill bit where high pressure jets and the bit will grind the soils ahead of the drill stem. The second stage involves enlarging this pilot hole to a diameter suitable for installation of the pipeline. A reamer is pulled back and rotated while pumping drilling fluid to cut and remove solids to enlarge the hole. A kind of reamer is the subject of this paper. The final stage consists of pulling the pipeline back into the pre-reamed hole. The most important part of the mechanical analysis is to define the boundary conditions for operating situations when the tool is under maximum load. In this paper we present a helpful description for giving boundary conditions to perform the numerical simulation of a barrel reamer.

The selection of sealing technologies of the subsoil and hydrotechnical structures and quality assurance

Abstract Various types of trenchless methods are extensively used to create engineering barriers for the purpose of achieving relatively low hydraulic conductivity of the subsoil and hydrotechnical structures. The most commonly used technologies of the grouting curtain creating are the DSM (Deep Soil Mixing), WIPS (Vibro Injcted Thin Wall), low-pressure injection and jet-grouting. Vertical barriers are widely used in environmental control systems to restrict the lateral spreading of liquid or gaseous contaminants and for seepage control through and beneath a levees. The barrier walls are constructed in a single or two phases using a slurry composed mainly of bentonite, cementitious materials and water. Often to solve complex geotechnical problems the technologies are combined (e.g. combining DSM and jet grouting). In the paper some examples of practical application of chosen types of technology dedicated different problems solving are presented. The results of geotechnical investigations of hydraulic permeability, shear strength and depth control of cut-off wall are given. The tests were carried out using BAT system, Cone Penetration Tests (CPT) and drillings. The presented test results should help define the technical and financial criteria that should be used to compare grouting based methods and other techniques applicable to the same geotechnical special works. These recommendations should permit an adequate application of grouting techniques and contribute to finding solutions for the delicate problem of ground sealing, notably when proceeding with hydrotechnical or environmental structures placed below water table.

Behavior of Sliplined Corrugated Steel Pipes under Parallel-Plate Loading

Some culverts and pipes installed under roadways several decades ago are reaching the end of their service life. The excavation and replacement of these buried structures will cause disruption to their service and require significant funding. Trenchless methods (e.g., sliplining) have been increasingly used to rehabilitate deteriorated buried structures (e.g., corroded steel pipes). Sliplining involves the placement of a new pipe liner inside an existing deteriorated pipe and the grouting of the space between the liner and the existing pipe. In this experimental study, parallel-plate loading tests were carried out to evaluate the effect of sliplining on the behavior of corrugated steel pipes with different degrees of corrosion. The nominal diameters of the corrugated steel pipes and polyvinyl chloride liner were 305 and 254 mm, respectively. This study investigated three different degrees of simulated corrosion of the steel pipes (0%, 50%, and 90%). The corrosion in each steel pipe was simulated by cutting out some steel segments along the invert of the pipe. A low-strength, normal-density grout was used to fill the space between the steel pipe and the liner. The pipes without and with sliplining were tested for their load-carrying capacity, stiffness, vertical and horizontal diameter changes, and average strains and curvatures. The experimental results show that prior to sliplining, the steel pipe with a 90% cutout behaved in a stiffer manner than that with a 50% cutout at a higher applied load. After sliplining, however, the steel pipe with 50% corrosion behaved in a stiffer manner than the pipe with a 90% cutout. Sliplining increased the load-carrying capacity and stiffness of the pipe. The location of the liner relative to the existing pipe had a minor effect on the behavior of the sliplined steel pipe.

Trenchless Sewer Rehabilitation Methods and Solving Diversity of Cured Sleeves Thickness

For the rehabilitation and renovation of sewerage and gutter networks, different methods and technologies have been introduced over the last half-century. The trenchless technologies are showing the greatest development. They are promoted for reasons of environmental friendliness, they do not restrict the space in the place of renovation and the implementation is fast. The paper focuses on specific material starting points for the use of trenchless methods. Trenchless methods do not generate waste from original pipelines. New pipes are installed in the existing pipeline, or a new pipeline pushes the old profile into the surrounding area. However, the new pipeline is not accessible for the traditional methodology of result control and product performance verification. Particularly for Cured-in-Place-Pipe (CIPP) methods, it is difficult to determine representative quantities for key features such as the thickness of the sanitary insets (sleeves) after curing, and it follows from practice that the measurements should be performed with a special spike gauge. CIPP products achieve all the final properties through the installation process in the existing pipeline. Simulation on semi-operative polygons is increasingly being used for research and verification of suitable representatives. Authors of the article began to address this issue in research, in collaboration with the company WOMBAT, s.r.o. when investigating the higher resistance of CIPP lining.

MODELING OF THE PROCESS OF CUTTING MINERAL GROUNDS BY PASSIVE WORKING DRAWNER DURING THE CONSTRUCTION OF CLOSED DRAINAGE

Objectives.The article describes an electronic model of the soil to study its rheological properties and study the process of cutting passive working bodies (knives) of mineral soils with trench-less method of building a closed drainage.Method.The essence of the method consists in cutting through the ground with the help of a passive working body of a narrow slit under a given slope and simultaneously laying a drainage (usually plastic) pipe with a filter on its bottom.Result.The trenchless method is characterized by the possibility of laying pipes at high speeds, the simplicity of the design of drainage machines and, most importantly, the possibility of building drainage in water-saturated and collapsing mineral soils. A big advantage is the possibility of using a drainage machine with a trenchless method in conditions of small slopes with a sufficient length of stacked drains.Conclusion.The study of the process of cutting mineral soils with narrow, deep knives on an electronic model makes it possible, at the design stage, to evaluate the effect of changes in various factors and parameters on the operating modes of the drainage machine; if necessary, make changes to the complex of works on the construction of drainage using the trenchless method with the help of the BDM-300 bed-draining machine, as well as to determine the composition and duration of the work operations of the trench-free bed-draining machine.

Evaluation of the Construction and Investment Process of a High-Pressure Gas Pipeline with Use of the Trenchless Method and Open Excavation Method. Analytic Hierarchy Process (AHP)

The study presents the application of multi-criteria analysis, i.e., the Analytic HierarchyProcess (AHP), for the evaluation of investments related to the realisation of a high-pressure gaspipeline. The authors evaluated the realisation of the gas pipeline with the use of alternativemethods: the trenchless Horizontal Directional Drilling (HDD) method and the open excavationmethod, based on the example of the construction of a high-pressure gas pipeline DN1000. Sectionslocated in naturally valuable areas on the route of the pipeline Wierzchowice-Kiełczów (Poland)were analysed, on the section from the valve station in Czeszów to the Kiełczów node. The researchconsidered the following criteria: technical costs, economic costs, social costs, and environmentalcosts. The sum of these partial estimations is the “total cost” of the investment. Research revealedthat the technical costs of the open excavation method are in all cases higher than the technologicalcosts of the trenchless method during the realisation of a gas pipeline (in the AHP analysis, theyreceive an average score of −4 or −3, compared to a score of −2 for the HDD method). On the otherhand, the economic costs are comparable, with a slight advantage for the HDD method. The overallscore for the open excavation method obtained with use of the AHP multi-criteria evaluation is, fordifferent variants, approximately −19, while the evaluation of the realisation of a gas pipeline withuse of the Horizontal Directional Drilling method gives a score from −15 to −10, depending on thesection.

Full-scale experimental study of the dynamic performance of buried drainage pipes under polymer grouting trenchless rehabilitation

Polymer grouting technology is a cost-effective and trenchless method for repairing leakage and subsidence of drainage pipelines. This paper reports the results of a full-scale experimental approach in the field, where we tested the structural dynamic responses, before and after polymer grouting trenchless repairing, of a reinforced concrete drainage pipeline of 700 mm inner diameter buried in dense soil and subjected to both surface impact loads and driving loads. The dynamic changes of three types of pipeline—the normal pipeline, disengaged pipeline, and polymer-repaired pipeline—is reported in detail in this paper for different soil cover depths, types and magnitudes of loads, and locations. The results show that under the surface load of the soil, the pipe experiences compression at its crown and bottom and tension at its springlines on both sides; moreover, the circumferential stress is greater than its longitudinal stress. An additional impact load or driving load has its greatest influence within 3 m on both sides of its point of action. The bell and spigot joints are the most vulnerable places in the pipeline. There the vertical displacement is discontinuous and relatively large when extra loads are applied. The dynamic response of the pipeline is greater to impact loads than to actual driving loads of comparable magnitude. Uneven pavement also enhances the response of a buried pipeline to the surface traffic load. Pipeline disengagement has a substantial negative effect on the overall mechanical resilience of the pipeline. However, polymer grouting can repair a disengaged pipeline effectively, even restoring its mechanical behavior to that of a normal pipeline.

РЕКОНСТРУКЦИЯ ТРУБОПРОВОДОВ С ИСПОЛЬЗОВАНИЕМ ПОЛИМЕРБЕТОНА

Accidents on sewers accompanied by the destruction of building structures have been a most serious problem not only for the water industry but also for the entire city. In the world the damage from the deterioration of reinforced concrete sewer tunnels and in-line structures due to corrosion is estimated at billions of euros per year. A way out of the current situation with corrosion in sewers can be timely and prompt repair and rehabilitation using protective coatings applied by trenchless methods. One of the methods of sewer rehabilitation is lining the internal walls of the sewers with plate composite materials (blocks) or continuous protective coatings where polymer concrete can be used. Polymer concrete comprises a thermosetting organic binder (usually epoxy resin) and a large amount of dispersed filler (talc, aerosil, crushed quartz, basalt, granite chips, etc.). The special composition of filler materials and advanced production technologies ensures the high qualities of polymer concrete. An assessment of the technical and economic indicators of the reconstruction of existing sewers and canals using polymer concrete blocks is given. Through a realistic example it is shown that the most effective option of the reconstruction of a sewer canal while ensuring environmental safety is lining with polymer concrete blocks (segments).

Studies of behaviour of the automatic control system of roadheader cutting heads movement

Boom–type roadheaders are basic machines used in underground mines for drilling roadways, in tunnelling and also for making underground buildings using trenchless methods. The article presents selected results of tests carried out in a semi–industrial scale, on a roadheader R–130, concerning behaviour of an innovative solution of system for automatic control of boom–type roadheader cutting heads’ movements. This important innovation, not known before in mining cutting machines, is the software control of cutting heads angular speed using a frequency converter. The text shows an impact of key values, from a perspective of an assumed control purpose, of programming device (setting system) parameters, achieving reference values for the actuators, on controlled facility behaviour when cutting a layered cement and sand block. The performance of the automatic control system without and with feedback to the setting system concerning an actual speed of cutting heads movement, which is important from the control system hardware perspective, was compared.

Performance of subsurface drainage implemented with trencher and trenchless machineries

The trenchless (T0) and trencher (T1) drainage installation methods are widely applied in Finland. There is an ongoing debate and a lack of science-based information about the performance differences between the methods. The objective was to assess drainage performance differences between T0 and T1 by analyzing groundwater table observations from field sections drained with the two methods. The differences were studied by using statistical analysis over a two-year period after the drainage installation. An experimental field in middle-Finland was divided into four T0 sections and four T1 sections. The groundwater level was manually measured about twice a week from seven locations in each section. Automatic recording was installed in one T0 section and one T1 section. The manual observations formed 56 time series, which were tested between the same-method plots (T0-T0 and T1-T1) and the different-method plots (T0-T1). Automatic data was used to validate the manual observations. In the T0 sections, 60–90% of the groundwater level observations were higher than those in the T1 sections. These observations had an average difference of 0.14–0.25 m. The variation in the groundwater level time series was larger between the T0 sections than between the T1 sections. Statistically significant differences between the same method field sections indicated that other factors also affected the groundwater table (soil type, etc.). However, the differences between T0 and T1 were stronger than those between the same-method sections, and the differences were clearest when the groundwater levels were above the drain depth (1.0 m). In the seasonal time series, the biggest differences were found during the autumn and winter periods. The average differences between T0 and T1 might not be significant in practice, but occasional larger (> 0.4 m) differences may have a short-term influence on field activities and crop growth.

Computer processing and simulation results of hydraulic experiments in the gravity pipelines and their protective coatings used in the construction and reconstruction of water disposal systems

On the basis of the known hydraulic dependences, which describe the fluid flow regimes in gravity pipe lines, the results of bench experimental studies on various types of pipeline materials and internal protective coatings have been analyzed in an automated mode. The simulation technique algorithm and the automated program are constructed in such a way as to be a kind of experiments’ catalogue (database) carried out on a universal hydraulic bench. The program content and the requirements to input and output information are presented herein. The results of an automated processing of the experimental data are given in the form of tables and graphical dependences, which characterize the liquid gravity flow regime depending on the degree of the pipelines roughness made of different materials. The target of the program is to provide a wide application of its results by the designers as tool in their design works when designing gravity water discharge lines, as well as in construction, modernization and renovation of pipeline transport facilities focusing on the trenchless repair methods. The program has a special unit, which assesses and compares domestic and foreign methods of hydraulic calculations of pipe lines through the roughness coefficients determined by the formulas of Manning and N.N. Pavlovskiy.

Seismic response of buried pipes to microtunnelling method under earthquake loads

Microtunnelling is a of trenchless method excavation that had great growth in recent years and it has been used to install water, sewage, oil and gas pipelines using powerful hydraulic jacks for pushing special pipes. In this study, regards to the importance of microtunnelling resistance against earthquake, it is attended to the seismic dynamic analysis under the earthquake force. Failure and destruction in microtunnelling pipes, cause it's lack of efficiency in the aftermath of the earthquake and may even cause a fire and irreversible events and regards that microtunnelling pipes are vital arteries, immune and resistance against earthquake is inevitable. In this study changes of the diameter, thickness, depth, length and material of the microtunnelling pipes and the type of their surrounding soil and changes in the underground water level under the earthquake load by modeling in FLAC 3D software are investigated. The results of this study show that increasing the diameter of microtunnelling pipes increases its displacements of the soil around by 0.59% and decrease it's resistance against seismic waves. Increasing the thickness of microtunnelling pipes reduces the displacements of its surrounding soil to 0.33%. By increasing the stiffness of microtunneling pipes, the displacements of its soil around will reduce by 2.5%. Based on the results obtained, by increasing length of the microtunnelling pipe under the earthquake load, displacements in the soil around the pipe increase by 18% and may cause damage to the pipe. Also the joint area of buried pipes is more damageable than their sidewall during the earthquake. By increasing depth of the pipes the displacements reduces by 27.5%. In this study by reducing the groundwater level the displacements of the soil around the pipes reduce to 7% and recommended to use methods such as digging drainage wells to reduce buried pipe floats. By increasing the soil parameters such as the bulk and shear modulus, friction angle, and cohesion in the microtunnelling surrounding soil, the displacements will decrease to 41%. It is concluded that the depth of the pipes and the type of their surrounding soil have the greatest effect on increasing of the pipes resistance and reducing its vulnerability against the earthquake.

Multi-segment trenchless technology method selection algorithm for buried pipelines

There are many tools, models, and algorithms to aid in the selection of appropriate trenchless methods for pipeline installation or rehabilitation. However, one key concern is which method or technique provides optimum solution to the rehabilitation of multiple pipe segments rather than just a single pipe segment. Therefore, the searching criterion for an optimum decision support system is divided into two parts. First, the selection of the optimum method capable of solving the problem properly. Second, a simultaneous analysis of other parameters such as cost, time, and quality to improve the overall benefits of the project. It is observed that most of the real-world cases involves multiple segments in a single project. Therefore, an optimization of the solution must be made for those multiple pipe segments. Although use of different methods for each segment is a preferable solution, it may not be feasible in a wider consideration of project cost, quality, and time. Hence, one way to determine the optimal solution for multiple line segments is to minimize the number of methods and their anticipated total costs which include direct costs and social costs. This paper presents a mathematical approach to expedite the optimum solution by evaluating all of the trenchless technology methods capable of installing, replacing, or rehabilitating each pipe segment (a solution set) and minimizing the number of methods and their total costs.