Pipelines 2020: Condition Assessment, Construction, Rehabilitation, and Trenchless Technologies

Infrastructure asset management domain has an extensive advancement in condition assessment and rehabilitation decision models. However, most of the focus is devoted to pipelines, giving little attention toward manholes. Recent studies revealed that more than three-million manholes in the United States (U.S.) have structural deficiencies. Defective manholes are a main source of the inflow/infiltration and contribute up to 50% of the collection system’s input to treatment plants. As a result, it is of great importance to assess them on a regular-basis to avoid any operational and structural failure. The main objective of this study is to develop a condition assessment model for sewer manholes. The model divides the manhole into several components and filters the possible observed distress in each element. Later, the study determines the relative importance weight of each component using the analytic network process (ANP) decision-making method. Moreover, the condition of the manhole is computed by aggregating the condition of each component with its corresponding weight. As a result, the proposed assessment model will enable decision-makers to have a final index suggesting the overall condition of the manhole and a backward analysis to check the condition of each component. Thus, better decisions are made pertinent to maintenance, rehabilitation, and replacement actions.

The water main replacement program at WSSC Water has been on-going for several years and it now contains data obtained from various sources, including construction practices and condition assessment, that can provide more insights into the root cause of water main breaks. Generally, several factors can contribute toward water main breaks such as internal and external corrosion, load stresses, pressure transients, material properties (including vintage), and construction practices. WSSC Water already includes many of those factors in its water main replacement recommendations process. Recently, based on anecdotal field evidence, WSSC Water sought to determine if there was a correlation between breaks occurring on old cast iron mains that were connected to the newly replaced ductile iron mains. This paper discusses process development and data analysis techniques used in determining any systemic issues of water main failure due to tying new pipes to old water mains. The analysis showed a small count of breaks associated with the tie-in pipes but overall did not find any substantive correlation. Out of the 2,367 counts of the tie-in pipes, there were only 39 counts of tie-in pipes with water main breaks. Although no significant correlation could be established, there are few insights that are recommended for future analysis such as data refinement or determining the effective length of existing water mains impacted by tie-in pipes. The data analysis techniques established here could benefit future similar hypotheses analyzed for validity using similar principles.

Rationalizing and prioritizing condition assessment programs for large diameter water main networks are critical aspects of overall system asset management for virtually all water utility managers. Larger diameter mains are not feasible to be managed in response to failures, they require a dedicated condition assessment program to facilitate timely intervention before failure. As advanced condition assessment techniques can be very costly and inherently present their own risks associated with deployment, it is essential that the appropriate technology be selected in a staged manner with prioritization and schedule driven by true risk exposure. Winnipeg, MB, operates a water system that services a population of over 800,000. While the age of the system dates to the 1800s, the largest growth and network development occurred over the 1950s and 1960s. The majority of larger diameter water mains (>600 mm) were constructed of prestressed concrete cylinder pipe (PCCP) while larger mains up 600 mm are largely Asbestos Cement (AC). The native soils in Winnipeg are very corrosive to ferrous metals and some areas have extremely high soluble sulphate levels (>5,000 mm) which can be very damaging to cementitious materials. Being a cold climate environment, the City also uses de-icing salts extensively, which are known to elevate chloride levels in the soil and can be quite harmful to the corrosion protection properties of the exterior mortar of PCCP pipe. The age of much of the network and the exposure conditions highlights the need to better understand true physical condition. This case study presents the risk-based approach utilized to screen a feeder main network including some very innovative tools to assess risk comprehensively in a desktop model. An applied loads/deterioration tool was utilized that can analyze the combined effects of pressure, external loads, exposure conditions, and the unique design basis for each pipe segment in in the system in terms of its predicted factor of safety against failure. As the computational model can solve the entire network in near real time, it can be run in scenario analysis modes to provide increased clarity on which portion of the network should be assessed, when, in what order, and by what suite of CA technologies.

The Frontera Lift Station directs 10 million gallons of wastewater per day (MGD) into two (2) parallel force mains (welded steel pipe with cement mortar lining) a distance of 3.67 mi to the John T. Hickerson Water Reclamation Facility (Facility). The 30/36/42-in dual force mains are critical pipelines with a high consequence of failure as they are the only pipeline system that conveys wastewater flow from the entire westside of El Paso to the facility. Additionally, the force mains traverse through residential, commercial, and industrial areas, through open desert and arroyos, and under a recently constructed freeway. Due to the high consequence of failure and the several relocations required to accommodate roadway improvement projects since their installation nearly 20 over 25 years ago, El Paso Water implemented a proactive decision intelligence approach to condition assessment. This includes evaluating the current condition and long-term utilization of the force mains, and to obtaining actionable information on immediate concerns including leaks, gas pockets, and pipes with significant wall loss. Prior to the subject inspection, Jacobs and El Paso Water completed a desktop study, testing, and mapping of existing soils corrosion potential along the pipeline alignment, an initial cathodic protection system analysis, and limited external pipe investigations. Following and based on this work, El Paso water elected to inspect the force mains employing Pure Technologies-Xylem for the subject condition assessment, of the south force main from the Frontera LS to the treatment Facility. The subject condition assessment of the Frontera lift station force main included an internal acoustic leak and gas pocket inspection to detect leaks and pockets of trapped hydrogen sulfide gas, an internal electromagnetic inspection to identify pipes with wall loss, an evaluation of the cathodic protection system, and development of a map of the buried infrastructure alignment.

Pipes are among the important components of the U.S. infrastructure. Deflection monitoring of gravity pipes, such as culverts or sewer pipelines, provides an invaluable information of the pipe’s structural condition to the decision makers. Conventionally, laser profilers are used for dry pipes to accurately measure their profile. However, laser profilers are very expensive, cumbersome to transport, and they require an expert to operate. Digital image correlation (DIC) is an inexpensive alternative to the conventionally used laser profilers to measure the pipe’s profile and consequently its deflection accurately over time. In this paper, feasibility of DIC for pipe profiling is investigated and verified through several linear variable differential transformers (LVDTs) and cable displacement sensors (CDSs). Two 5.5-ft long, 60-in. circular corrugated metal pipes (CMPs) and one equivalent size arch CMP were embedded, instrumented and subjected to static load using an MTS hydraulic actuator under the laboratory condition. The inside of two circular CMPs were lined by a polymeric spray applied pipe lining (SAPL) to investigate the effect of liner brittle failure (i.e., cracking) on the accuracy of DIC. The pipes were loaded until the ultimate bearing capacity of the composite system was reached. The profiles of pipe samples were measured before, after and during the loading to calculate their respective deflections using DIC. In this study, MATLAB and a commercially available software, GOM Correlate, were used to obtain the pipe samples’ profile. The result shows an excellent agreement between DIC, LVDTs, and CDSs. It is recommended that potential use of DIC in the actual field conditions be investigated for laser profiler substitution.

Assessing pipes and manholes of a large sewer network to provide rehab recommendations can be challenging and daunting. Performing this analysis accurately and quickly takes a different meaning for a utility that is under a consent decree, like DeKalb County, GA. Assessing all sewer assets requires collecting and managing high volumes of pipeline assessment certification program (PACP) and anhole assessment certification program (MACP) inspection data provided by contractors in multiple submittals. After submitting the inspection data, it is crucial to manage, review, and process them in a timely fashion. Unfortunately, many utilities perform this manually, significantly delaying data processing time, and reducing their capability to prevent sanitary sewer overflows (SSOs). During review, data can be duplicated or lost, making data management, and work order tracking difficult. Additionally, the condition assessment tools currently in the market lack the capability to process multiple databases, forcing the analyst to run each database individually. To be more efficient, utilities often perform multiple inspections of related rehab projects concurrently, increasing the number of submitted databases. This increases processing time and creates a data storage/management issue. The County recognized these issues during the collection phase and developed and implemented new tools to resolve the issues. This presentation will focus on demonstrating the value of automating quality check (QC) tools to provide quality data feedback to inspectors, drastically reducing iteration cycles during the data submittal process. The presentation will also demonstrate gained efficiencies by creating a database consolidation tool for analysis. These tools in combination with data management best practices helped County staff to better track and analyze PACP and MACP inspection databases. As a result, DeKalb County reduced any opportunity to lose or duplicate data, hindering analysis gaps, and providing unreliable results. Previously, a process that could take up to 880 h can now run under 40 h, freeing up staff to focus on other critical tasks that needed their attention.

This paper discusses a condition assessment for a water distribution network in Freetown, Sierra Leone. The water supply for Freetown comes from seasonal rainfall which is stored within multiple catchments located in the hills above the city. The water supply is dispersed via gravity to a series of reservoirs and through a distribution network, comprised of approximately 170 mi of pipelines originally constructed in the early 1900s, and significantly expanded by the Guma Valley Water Company (GVWC) in the 1960s. The water leakage rate is estimated to range between 35% and 40% system-wide, and the most significant contributors to overall water leakage are exposed pipes and low quality plastic service connections, referred to as “spaghetti” pipes. The study evaluated the condition of the physical pipe network, underlying issues related to leakage, water quality implications, and recommended improvements for rehabilitation.

Pipelines remain the primary means of transporting and delivering petroleum products, natural gas, liquid hydrocarbons, and water to consumers. Gas pipeline leaks which are the main threat to the reliability of the pipeline network can cause major incidents and environmental disasters resulting in both human injuries and financial losses. As technology is gaining traction for monitoring infrastructure, it is expected that the efficient application of emerging technologies will play a crucial role in the realization of real-time structural integrity and leak detection, monitoring, and repair systems for gas pipelines. The primary objective of this study is to conduct a state-of-the-art review and evaluation of emerging technologies and systems for pipeline leak detection. The capabilities of the identified technologies and systems are analyzed to elicit their advantages and disadvantages. Based on the findings of the study, recommendations are made on best practices for the application of these emerging technologies and systems.

El Paso Water (EPW) is recognized for their efforts in water conservation and asset management. In 2015, as part of their capital improvement plan EPW implemented a condition assessment program utilizing advanced electromagnetic technologies to evaluate the condition of the their essential 48-in. cross city transmission main (CCTM). Since the program’s initiation, EPW has inspected over 6-mi of the CCTM infrastructure. The purpose of the program is to monitor the condition of critical pipes, maximize remaining useful life, prevent unexpected failures, and avoid large scale water-loss events. EPW has successfully employed innovative technology to collect condition data specific to each pipe within the CCTM, allowing each pipe to be managed as an individual asset. The electromagnetic inspection data collected is utilized to determine the structural adequacy of the pipe. In addition, a visual evaluation of the pipeline interior is performed to identify other potential deficiencies. This proactive approach allows EPW to make informed decisions based on reliable and “actionable” data to develop strategic decisions for the repair or replacement of individual pipes approaching failure. Such an approach allows EPW to save significant capital when compared to the significant costs associated with replacing sections of pipe or the entire pipeline. This paper will demonstrate the importance of the CCTM and present an overview of El Paso Water’s condition assessment program. Furthermore, the paper will provide cumulative results and include highlights of lessons learned since the program’s inception 4 years ago.

Utility managers and owners have challenges when addressing appropriate intervals for inspection of gravity sanitary sewer pipelines and other underground pipeline systems. Closed-circuit television (CCTV) inspection technology is the most common method to identify aging sewer pipes requiring rehabilitation. While these inspections provide essential information on the condition of pipes, assessing all pipes in the network is expensive, and often limited to small portions of an entire sewer system. Therefore, it would be more beneficial to use predictive analytics to leverage existing inspection datasets and then forecast the condition of pipes that have not yet been inspected. The predictive capabilities of machine learning model, namely gradient boosting tree is demonstrated based on data provided by inspection reports from City of Tampa. Three main factors, physical, operational, and environmental were considered during the selection of variables in development of this model. Thirteen independent variables including pipe’s age, material, diameter, flow rate, pipe segment length, depth, slope, soil type, pH, sulfate content, water table, soil hydraulic group, and soil corrosivity were used to build the prediction model. Complications posed by imbalance between condition classes are overcome by changing the classification classes into a binary format (where pipes are in either good or critical structural condition) and then the receiver-operating characteristic (ROC) and confusion matrix were used to measure the performance of the model. The developed model showed 87% accuracy to predict condition of un-inspected sewer pipes. The results can be used by utility companies and municipalities to forecast condition of sanitary sewer pipes, schedule inspection times, and make cost-effective decisions to match budget allocations.

There are various methods to predict the wastewater pipe deterioration for the actual and future conditions of wastewater pipes. These methods can help decision-makers to plan for future inspection. Therefore, developing an accurate prediction of wastewater pipe deterioration is one of the key components as it helps infrastructure agencies to predict the remaining asset life. The main goal of this research is to develop a predictive model for wastewater pipes using random forest classification. The predictive models can efficiently predict wastewater status and can increase the certainty level of the current condition of wastewater pipes. The dataset of this study is obtained from the City of Los Angeles, which represents current wastewater information of the mainline sewer pipes. The developed random forest classification model has achieved a stratified test set false-negative rate, the false-positive rate, and an excellent area under the ROC curve of 0.81 in a case study application for the City of LA, California. An area under the ROC curve >0.80 indicates the developed model is an “excellent” choice for predicting the condition of pipes in a sewer network. The model developed is an essential decision support tool for wastewater utility managers in their prioritization of inspection, maintenance, and replacement.

Watermains distribution systems are critical assets that are prone to deterioration due to aging and other influencing factors. Although periodic inspections are needed, the physical assessment may involve extensive labor and financial burden on pipe owners. Therefore, it is paramount to prioritize watermains for assessment. While the risk-based approach is commonly used approach to prioritize watermains for assessment, the initial probability of failure is usually based on expert’s judgment and/or a hazard function that is based mainly on watermains breakage records. For those pipe owners with limited pipe breakage history records, they rely more on expert’s judgment. This paper presents a probabilistic failure model to prioritize pit cast iron pipes for assessment under combined internal pressure and external loading. While the corrosion pits that form during the process of graphitization is simulated using a power model, the in-service strength degradation is accounted for using the Weibull extreme value probability distribution. Uncertainty in the model was addressed using Monte Carlo Simulation.

Broken prestressing wire wraps are the primary cause of failure in prestressed concrete cylinder pipes (PCCP). This work examines the potential effects of the distribution of broken and intact prestressing wire wraps on the overall strength of PCCP. An advanced computational model based on non-linear finite element analysis was used to model the effect of scattered broken wire wraps versus contiguous broken wire wraps on the structural performance of PCCP. This study considers two distributions for broken wire wraps: scattered broken wire wraps through the length of the pipe and contiguous broken wire wraps in the barrel of the pipe. A sensitivity analysis was performed to evaluate visible cracking of the concrete core, yielding of the prestressing wires, steel cylinder with increasing internal pressure, and increasing number of broken wire wraps. A 60” embedded cylinder pipe (ECP) is modeled with 30 broken wire wraps in ten (10) different scenarios. The results of the scattered and contiguous broken wire wraps were compared. This information can be used by water and wastewater utilities to better understand the strength of PCCP in cases where broken wire wraps are scattered through the length of the pipe, leading to better risk management, and failure prevention of PCCP.

The City of Raleigh, NC, has implemented a proactive approach to evaluating the condition of their critical water transmission mains and raw water mains. In 2017, the City elected to inspect and perform condition assessment on a critical 14-inch steel water transmission main suspended from the Highway 64 bridge over the Neuse River. This is the City’s first inline inspection of a steel watermain and first use of the SeeSnake inspection tool. The City and their on-call contractor performed all pipeline modifications, flow isolation, and inspection support to provide safe access to the water main. This paper will be of interest to water and sewer utilities that desire to plan, design, and implement an asset management program that includes evaluation of metallic water mains; understand the logistical considerations and limitations of available inspection technologies; pre-planning required to implement the work; and interpretation of inspection data.

Submerged and buried assets such as piping, basins, and channels are costly to replace, difficult to inspect, and can catastrophically fail. The digester and thickening facilities upgrade (DTFU) project at the San José-Santa Clara Regional Wastewater Facility (RWF) involved isolation of approximately 2,000 linear feet (LF) of primary effluent (PE) and settled effluent (SES) reinforced concrete pipe (RCP) 78-, 96-, and 87-in. by 136-in. in diameter. During construction, they discovered holes with visible voids and soil at the crown of the 78-in. pipe. The adjacent wye junction structure also showed signs of severe corrosion within the interior top slab. This raised concerns about the neighboring 96- and 87-in. by 136-in. PE pipes, and ability to make future connections as designed. An emergency inspection of additional PE/SES pipes was initiated by the RWF. Flexibility, advanced planning, and proactive communication resulted in obtaining meaningful and actionable condition assessment data in a safe manner, without causing major disruptions to RWF operations. Crown corrosion was observed within all pipes from three inches of loss crown material to voids at the crown extending up to 22-in. into the soil above. This emergency project concluded with the replacement design of 200 LF of 78-in. PE/SES pipe, 10 LF of 87-in. by 136-in. pipe, 16 LF of 96-in. pipe, and wye junction structure with the other rehabilitation work deferred.

Jefferson County AL ESD owns and operates over 3,100 mi of gravity sanitary sewer and has been actively assessing and improving its sanitary sewer collection system. This case study will provide a detailed discussion of the inspection of 54” to 72” reinforced concrete pipe (RCP) sanitary sewers using closed circuit television (CCTV), sonar, laser profiling, core sampling, structural analysis, and field testing. The core sampling and lab testing were especially effective at understanding the remaining useful life of some of the RCP sewers that were observed with CCTV and laser profiling to have hydrogen sulfide (H₂S) microbial induced corrosion and concrete wall loss. The results of these assessments allowed the program to efficiently develop prioritized O&M and structural solutions. This project provided an immense benefit of delaying a proposed expensive sewer rehabilitation project for at least 7 years and this money can be reallocated to higher risk pipes and other projects that will have a much higher benefit to reducing overflows and increasing the useful life of degrading assets.

As indicated in AWWA C304 [the current design standard for Pre-stressed concrete cylinder pipe (PCCP)], the criterion for pipe serviceability is related to the material properties and state of stress (condition) of the concrete. The condition of the concrete can be evaluated by using sonic/ultrasonic testing to determine the structural condition and strength properties of the concrete core and coating. In many cases, PCCP failure is initiated by coating deterioration or cracking that allows moisture to migrate to the pre-stressing wire causing wire corrosion. This paper is a compilation of validations of sonic/ultrasonic PCCP testing. This testing includes conducting tests on PCCP at critical stages during pipe manufacturing process and testing on PCCP pipelines to identified distressed pipe by the sonic/ultrasonic testing. Distressed pipe located in a pipeline were excavated and removed for additional testing and verification. This paper discusses results obtained from Sonic/ultrasonic testing and the significances of these results.

On November 30, 2018, Anchorage, Alaska, experienced a 7.1 magnitude earthquake. The earthquake caused liquefaction within a lakebed resulting in a 48-inch ductile iron pipe (DIP) to become buoyant and float to the surface. Temporarily stabilizing and permanently repairing a large floating pipe located underneath a frozen lake while maintaining sewage conveyance was a challenge. This paper highlights the utility’s response effort to overcome the problems encountered and make the repair without a sewage release.

The construction manager at risk (CMAR) is a delivery method for projects to develop from conception through design and construction with emphasis on communication between the project’s owner, design engineer, and contractor, who together form the project team. This methodology for project delivery allows project teams to maintain a fluid state of communication on budget, design, and constructability to provide the best value project.

After reporting odor leakage, a DC Water engineer confirmed a 10-ft long missing section of concrete and steel cylinder at the crown of the 108 in. diameter Anacostia pressurized sanitary sewer force main. Made of pre-stressed concrete cylinder pipe (PCCP), the Anacostia main also showed areas of distress adjacent to the 10-ft missing section. When excavated to the springline, it was determined that the entire segment of the pipe was deteriorated. The crown section of pipe wall, including the interior mortar lining and steel cylinder, were no longer intact. Due to the critical nature of the line, live flow had to be maintained during the repair. The repair was design for internal pressure and external loads. The repair was performed in several steps including first patching the missing concrete core and steel cylinder using a sulphate resistant concrete to restore the host pipe. A shotcrete encasement was placed over the initial pour that repaired the continuity of the host pipe. A full reinforced concrete encasement was designed and placed to resist the internal pressure from typical force main operations. The encasement utilized micropile tie downs to resist uplift forces from the internal pressure because the pipe could not be excavated around the perimeter due to high ground water and daily surge of sewage. The entire repair was designed and completed with crews working around the clock.

In 2018, an unprecedented series of drenching rain storms catapulted Washington, DC, to the wettest year on record since 1871. The extreme rainfall stemmed from a parade of storms which unleashed several severe flood events on the Washington area. Per National Weather Service, there were 1,391 flood-related reports in the Washington-Baltimore region during 2018. This compares to only 262 reports in 2017. On July 8, 2019, a new single rain event record was set, as over 3.3” of rain fell in a one (1) hour period along the Potomac River. This is the most torrential rain event on record, and it led to cars flooding along major commuter roads and even basement flooding at the White House. This repetitious creek and street flooding is pushing the endurance of the buried and surface water infrastructure, most built more than a century ago, to the limit. This presentation aims to highlight DC Water’s collaborative efforts among all stake holders within the local and federal levels, in expediting our engineered effort to mitigate the high-consequence failures caused by mother nature. The creek bed construction of a circa 1890 masonry sanitary sewer that, not on pier, saw its bottom fall out when the creek bed embankment was flooded and washed out. A sinkhole by the side of Eclipse outside the White House closed a busy commuter street, at 17^th street NW, two blocks from Constitution Avenue. This “2019 White House Sinkhole” has its bullseye on top of DC Water’s buried regulator structure #29 with blind connection and masonry dam, circa 1878/1895. The back-to-back historic storm events also compromised a historic stone “log wall” retaining a robust road at the entrance of Georgetown Hospital, with buried 15-ft span brick culvert and 9-ft diameter inlet and outlet, by the side a federal wetland, all built in 1902. The high volume of runoff in the wetland during 2018 overpowered and collapsed the bulkhead beneath the retaining wall at the transition of 15-ft brick culvert to its upstream inlet with 9-ft diameter pipe. Before DC Water got NPS’ permit to implement a simple point repair, the record-breaking storm event on July 8, 2019, nearly washed out the entire bulkhead, sending a 15-ft long tree trunk through the torn bulkhead opening, resulting in a significantly larger and deeper washout at the foot of the retaining wall made of dry stack stone without any mortar. Upon engineering assessment and confirmation of the pull-away displacement in culvert brick wall, as well as the stacked stone retaining wall seated on the brick arch crown, DC Water went into expedited mitigation with in-house design and contracting to stabilize and protect this historic infrastructure.

Citizens Energy Group (Citizens) is implementing a long-term control plan to address combined sewer overflows (CSOs) in Indianapolis, Indiana. The “DigIndy” plan includes provisions for a series of CSO diversion structures, consolidation sewers, screen and gate structures, approach channels, drop shafts, and a tunnel for storage and conveyance. There are multiple tunnel segments and corresponding near surface projects planned over a span of 10–15 years. The paper discusses the overall tunnel system and highlights the recent near surface sewer projects. The projects are near surface sewer projects under construction in 2018–2020 including multiple cast in place concrete structures to divert flow from a CSO to the Dig Indy tunnel through large diameter collection and consolidation sewers. Sewer installation includes trenchless technology and open cut excavations in multiple locations. The challenges of construction in an urban environment around numerous existing utilities while coordinating with other municipal projects will be discussed.

Pipe and labor costs constitute about seventy percent of pipeline project costs. The accurate prediction of pipe and labor costs is invaluable for cost estimation of capital pipeline projects by helping to eliminate or at least reduce cost under- or over-estimations. The research objective of this paper is to develop and compare various time series methods to forecast pipe and labor costs. The 20-city average pipe and labor costs from 1995 to 2016 published monthly by Engineering News-Record (ENR) were used to develop the time series models. The accuracies of these forecasting models were evaluated using ENR pipe and labor cost data from 2017 to 2019. The results show that predictions with seasonal autoregressive integrated moving average (ARIMA) models are more accurate than those with the other models, such as Holt exponential smoothing. The results contribute to pipeline construction community by helping cost estimators to prepare more accurate bids for pipeline projects.

Contra Costa Water District (District) has worked since 2006 to replace approximately 21,000 ft of unlined canal with a 10-foot diameter concrete pipeline. Drivers for the project include increased flood protection and public safety, as well as protection of water quality from groundwater intrusion. If constructing a 10-ft diameter pipeline wasn’t challenging enough, this project faced a number of technical and logistical challenges encountered along the way, including stringent regulatory requirements, unsuitable soft ground conditions, and large material import requirements. Leveraging the broad experience of project partners and applying adaptive approaches to project challenges, the first four of the project’s five segments have been successfully constructed, totaling approximately 13,000 ft.

The City of Houston (the City), the 4th largest city in U.S., but compared to much of the country, is not very old. The oldest water infrastructure in the City dates to the 1930s, and most of the main transmission system is no older than the 1970s. This is the story of one 96-in. transmission line constructed around 1990. This line conveys over 100 million gallons per day (MGD) on an average day to the downtown and western areas, making it one of the City’s most critical pipelines. The line stretches about 10 mi and was constructed in three contracts. The first contract consisted of about 10,000 ft of steel pipe, and the remainder was constructed of prestressed concrete pipe. Over the course of its life so far, several significant events have revealed its vulnerability, and also highlighted the benefit of proactive condition assessment and planning.

A new 72-in. butterfly valve (BFV), replacement of an 84-in. BFV and 84-in. BFV seat replacement were planned to be installed by the City of Houston (City) to improve operational flexibility at a major interconnection serving the Houston Central Business District and the entire west side of Houston. To perform the work, segments of the 72- and 84-in. water lines were required to be isolated and dewatered to accomplish the proposed work. The limits of the shutdown extended past existing interconnections coming off the 84- and 72-in. water lines. An interconnection between the 72- and a 60-in. water line was required to be in service at Emancipation Ave. and Bell St. to maintain the water supply to Downtown Districts. A 72-in. temporary line stop valve was proposed to keep the interconnection in service to meet the water demands and prevent major city-wide impacts to the water system. The 72-in. line stop installation required two attempts to properly insert and stop flow adequately. On the first installation attempt the wings on the folding head needed machining to allow the full circumference to touch the inside diameter of the water line and plug the line. With the line stop installed, the Contractor successfully installed the 72-in. BFV, replaced the 84-inch BFV and internal valve seat with no interruption to the water supply.

The integrity of buried large diameter flexible pipe, with its dependence on the embedment and surrounding soil, can be especially susceptible to the level of care taken during installation. As the number, size, and length of our water and wastewater pipelines grow to serve a rising population in increasingly urbanized environments, it becomes more and more imperative that they be constructed to a high quality to ensure structural longevity, maintain hydraulic performance, and minimize risk of failure. This paper will discuss some of the measures that may be incorporated in the design, construction, and inspection of a flexible pipeline to improve the quality of installation. Project examples will be used to consider the relative cost and effectiveness of the various measures.

The Tarrant Regional Water District (TRWD), with its partner the City of Dallas Water Utilities (DWU), is currently engaged in the planning, design, and implementation of a 350 MGD raw water transmission system, which will run across north central Texas from Lake Palestine to Lake Benbrook, with connections to Cedar Creek Reservoir, Richland Chambers Reservoir, and a Dallas delivery point. Collectively, the system consists of approximately 145 mi. of 84- to 108-in. pipeline, a 5-mi 120-in. diameter tunnel, six 100-350 MGD pump stations, one 450 MG balancing reservoir, and ancillary facilities. The program developed by TRWD and DWU to accomplish these improvements is called the Integrated Pipeline Project (IPL). Procurement of over $845M in construction and $38M in owner furnished equipment has been a significant challenge for the IPL program. To date, 16 separate construction contracts and 10 contracts for owner furnished equipment have been awarded as part of the program. Selection of contractors and equipment manufacturers was one of the most significant risk factors identified in risk management workshops for the program. TRWD has used a competitive sealed proposal process, along with contractor prequalification, to select the best entities to construct the projects and provide key equipment as a way to mitigate this risk. This paper will discuss the procedures used for competitive sealed proposals, modifications made to the process to correct initial assumptions, and specific performance metrics used to compare the initial and final cost of projects to determine if these risk management strategies were effective.

The potential cause of the sinkhole was failure of the CMP storm drain. The CMP experienced flattening of the profile, corrosion of the invert, and open joints. The potential causes of the CMP failure were the naturally corrosive nature of the soils, age of the culvert, poor workmanship in installing the culvert, and poor design. This project encountered numerous complicating factors including: (1) the roadway is sole access to critical base assets. The roadway remained open to restricted weight loads, less than normal requirements; (2) access and work area required the base and contractor to expedite clearing affected areas for permitting including biology, archeology, Native American, surveyor, etc.; (3) the existing CMP culvert was comprised of several section of CMP with various shapes and sizes. The largest of these was approximately 7-ft in diameter; (4) there were three grade breaks within the CMP alignment. The breaks allowed the storm water to fall approximately 2 ft over a run of 2 ft; (5) the existing alignment for repair was approximately 270 ft in length with a left horizontal curve with a radius of approximately 1,500 ft and approximately 120°; (6) the CMP was galvanized steel with a bitumen lining; (7) the culvert invert was cast concrete; (8) the proposed tunnel construction replacement method had to negotiate the curved alignment, consume the CMP, and then allow for abandonment or removal of the proposed construction equipment while still supporting the failed ground above the tunnel termination. The tunnel replacement ended at the concrete tunnel, start of the railroad easement; (9) the work area and access were tightly controlled to avoid protected habitat and sensitive cultural resources while maintain a safe grade; (10) the work area required a method to divert storm water in the event of rain. The channel is subject to flash flooding; and (11) short design and construction schedule.

The Bois d’Arc Lake Project is an estimated $1.6 billion water delivery program to expand North Texas Municipal Water District’s (NTMWD) regional water system. This program consists of numerous individual components that must be orchestrated concurrently to collect, treat, and transport water from the first major reservoir to be built in Texas in nearly 30 years to 80 different North Texas communities. The major components consist of a reservoir dam and raw water intake, raw water pump station, raw water conveyance pipeline, various roadway, and bridge improvements, environmental mitigation, terminal storage reservoir, high service pump station, water treatment plant, and treated water pipeline. Garney Construction was awarded Construction Manager at Risk (CMAR) services for two critical components of this project—the water treatment plant as well as the raw and treated water pipelines. Garney is responsible for the entirety of the raw and treated water pipelines, including preconstruction design services, coordination, scheduling, estimating, management, oversight, portions of construction, and cost management. The pipelines portion of this project will be constructed in two phases. The first phase of work consists of approximately 35 mi of 90-in. transmission main to transfer water from the newly constructed reservoir to a terminal storage reservoir in Leonard, Texas. This portion of the alignment is contained within Fannin County. The second phase of work consists of approximately 25 mi of 84-in. pipeline to convey potable water from the newly constructed Leonard Water Treatment Plant to a terminal connection near McKinney, TX, within NTMWD’s existing regional water system. This portion of the alignment extends across Fannin and Collin County as well as a small section of Hunt County. The CMAR delivery method is an ideal selection for a project of this magnitude. By virtue of the shear distance (approximately 60 mi), there are a multitude of challenges that vary along the course of the pipeline alignment. The northern portion of the raw water alignment is predominantly rural in nature, while the southern portion of the treated water alignment is more populated. Consequently, the diversity from one end of the project to the other poses many different and unique types of challenges. Having a competent and qualified CMAR contractor engaged early in the design aids not only to mitigate those challenges, but also to facilitate advancement of design without sacrificing completion milestones. Unlike the traditional design-bid-build delivery method, the CMAR delivery method allows for participation during the design phase. Being a participant in the design phase empowers the CMAR to offer construability suggestions, review public relations concerns, and develop initial construction sequencing of work. Furthermore, the CMAR is afforded the opportunity to procure long lead materials as well as execute construction contracts prior to final design. Ultimately, this delivery method allows the CMAR to overcome many of the schedule and design constraints that are typical of a traditional delivery method.

East Bay Municipal Utility District (District) has embarked on the replacement of aging water transmission pipeline to improve seismic reliability of the area’s domestic and emergency water service. The District recently started the construction of the $40 Million replacement of critical pipeline and facilities at the San Pablo Water Treatment Plant (WTP) in Kensington, California. The San Pablo Clear Well Replacement Project (Project) includes the demolition of the existing clearwell, construction of two 3.5 Million Gallon concrete tanks within the basin of the existing clearwell, demolition and replacement of the San Pablo Rate Control Station (RCS), rehabilitation work on the San Pablo WTP, and the installation of approximately 1,250 feet of onsite and offsite large diameter transmission pipelines. This critical facility serves the cities of Oakland, Berkeley, El Cerrito, Richmond, and other surrounding towns and communities. Prior to construction, District Forces are required to perform six separate shutdowns to existing large-diameter pipelines ranging from 24-inch to 54-inch and temporary outages of the existing valve and pump facilities to support installation of new pipelines. Each shutdown requires isolation of large diameter valves (most have never been exercised), complex operational outage planning and sequencing, dewatering and discharging of large volume of potable water into the nearby waterway, and meeting a stringent timeline to minimize impacts to the system. Pipeline construction in a narrow dead-end residential roadway within a tight operational time-frame requires extensive community outreach, permitting agreements, and a collaborative relationship with the contractor. This paper discusses the construction phase of the project and the innovative solutions used to resolve operational outage constraints, permitting, pipeline delivery, and installation challenges.

Beta Construction of Seattle, Washington, began installation in November, 1989 of an 8,432 foot long 48-in. gravity sewer line that was installed across exclusive Campbell Lake in Anchorage, Alaska. In a unique and propitious series of events, the City of Anchorage and the Corps of Engineers collaborated on dam repairs and gravity sewer installation saving significant dollars for underwater construction and resulting almost 30 years later in unintended consequences. Unlike most unintended consequences, these were positive, even remarkably so. On November 30, 2018, a magnitude 7.1 earthquake struck the Alaska-Aleutian Subduction Zone and liquefied the lakebed. While the 29-year old 48-in. diameter gravity sewer installation was dramatically disturbed, and while the disturbance went unnoticed for 104 days under ice, there was no sewage spill and repairs were able to be made with minimal complications. This paper will highlight the circumstances of the original construction and how material selection and construction methods resulted in a positive outcome years later before the advent of today’s innovative and resilient seismic joints.

For a flexible pipe to be installed successfully, there are several factors that must be taken into consideration during the construction phase. This paper will discuss how the requirement of a pipe proving procedure prior to pipe installation can benefit a project’s construction phase by establishing a baseline for an acceptable pipe installation method and ensuring the pipe is installed in accordance with its design.

In 2018, Louisville, Kentucky’s wettest year on record, Louisville Metropolitan Sewer District (MSD) was faced with the daunting task of repairing the old Ohio River Interceptor (ORI), an 84-in. non circular combined sewer in the heart of downtown Louisville that carries 40 million gallons per day (MGD) of raw sewage during dry weather. Structural evaluation of the ORI concluded that sections under historic Main Street—downtown Louisville’s business, entertainment, and hospitality district—had significant concrete loss and was failing. The team, consisting of the Owner, Engineer, and Contractor collaboratively developed a repair solution for 1,400 linear feet (LF) that included a hydrogen sulfide (H2S)-resistant polyvinyl chloride (PVC) panel liner system that was easily installed to fit the unique shape of the sewer, maximizing hydraulic capacity of the repaired ORI. The structural repair included rebar and grout behind the liner. The repair solution required all upstream flows be diverted around the repair area. A temporary 40 MGD pump station and approximately 11,000 LF of 18-inch forcemain was strategically routed to minimize utility conflicts, traffic, and business impacts, and Main Street visibility. Prior to beginning rehabilitation work, a partial sewer collapse and related 60-ft diameter conical-shaped void below the pavement section was discovered approximately 80 ft into the ORI. The engineers quickly coordinated with contractors on structural design changes to accommodate a ring beam system to stabilize the tunnel for the first 165 ft and incorporated it into the permanent repair to maintain the original structural design’s internal diameter and prevent further loss of hydraulic capacity. Additionally, three consent decree required CSO connection improvement projects, located in the repair area, were added to the project to minimize impacts to stakeholders. Potential failure of the ORI put public safety, water quality, business operations, tourism, and MSD’s operations at risk. The cost-effective solution minimized disruption to downtown, minimized environmental impacts to the Ohio River, and was completed on schedule, saving the City and MSD millions of dollars. The repair has provided ratepayers with a safe, reliable sewer asset for the foreseeable future.

The Tarrant Regional Water District (TRWD) with the City of Dallas Water Utilities (DWU), are currently engaged in the planning, design, and implementation of a 350 MGD raw water transmission system, which will run across north central Texas from Lake Palestine to Lake Benbrook, with connections to Cedar Creek Reservoir, Richland Chambers Reservoir, and a Dallas delivery point. Collectively, the system consists of approximately 145 mi of 84- to 108-in. pipeline, a 5-mi 120-in. diameter tunnel, six 100-350 MGD pump stations, one 450 MG balancing reservoir, and ancillary facilities. The program developed by TRWD to accomplish these improvements is called the integrated pipeline project (IPL). The IPL program consists of dozens of projects from design phase to equipment pre-purchases and construction. To manage these myriad projects, a standard Quality Management approach was adopted to ensure individual projects meet overall program goals. Starting in 2013 and continuing to present, Phases 1 and 2 of IPL Construction consist of 17 construction contracts (80 mi of 84”–108” pipeline, three pressure reducing stations, two pump stations, a balancing reservoir, etc.) and nine equipment pre-purchase packages. This includes nine different contractors, 13 pipe and equipment suppliers and numerous subcontractors, design engineers, and consultants. To provide consistent, high quality finished product to the Owner, significant quality management measures were essential for this project. This paper will discuss quality management processes, decisions, and lessons learned focused on pipe design, manufacturing, and installation for this interesting project.

The Orange County Water District Groundwater Replenishment System treats secondary effluent from Orange County Sanitation District’s wastewater treatment plant in California through microfiltration, reverse osmosis, and advanced oxidation for groundwater recharge. The facility produces 100 million gallons per day of purified water. Since 2008, the water from the facility has been conveyed to recharge facilities via a cement mortar lined steel pipeline. Inspections have revealed deterioration of the lining. The highly purified water has low mineral content and tends to corrode cementitious material. Lime is added to reduce corrosiveness, but the targeted alkalinity has not always been achieved. Improvements have been made to stabilize the GWRS product water however, degradation has continued, and rehabilitation technologies were explored. In September 2018, F.D. Thomas, Inc., applied epoxy to 20,000 linear feet of 78-in. pipeline. Since completion of the project, solids loading in the water has shown a 75% decrease, indicating that the epoxy has prevented the lining from deteriorating further. In April 2020, an inspection of the epoxy will be performed.

Salt Lake Department of Public Utilities (SLCDPU) has engaged Jacobs Engineering (Jacobs) to investigate odor and corrosion issues within the sewer collection system. Most critical pipes in the collection system are composed of RCP or brick, making corrosion a primary concern. A Jacobs team conducted hydrogen sulfide (H₂S) vapor and liquid phase sampling throughout the three main trunk lines in the City. In combination with system flow rates and rainfall data, this data was used to identify hot spots of hydrogen sulfide, and potential corrosion, within the sewer system. The data collected during the sampling campaign was used to calibrate a wastewater process model built for the SLCDPU wastewater collection system using the INTERCEPTOR Powered by WATS model. Wastewater quality parameter information used during calibration included temperature, pH, alkalinity, sulfate, dissolved oxygen (DO), and chemical oxygen demand (COD). The H₂S formation rate was calibrated using dissolved sulfides and sewer headspace hydrogen sulfide data. The model, in combination with bench scale testing of ferric chloride, ferrous chloride, sodium hypochlorite, and hydrogen peroxide, was used to recommend an odor and corrosion control mitigation strategy for the existing system as well as for several future build-out scenarios incorporating the Water Reclamation Facility upgrade and state prison relocation and associated collection system projects. These recommendations were further refined with fan testing at key locations along the trunk lines to address odor and corrosion concerns.

The Odessa Groundwater Replacement Program (OGWRP) was put in place to develop alternatives to groundwater and reduce depletion of the Odessa aquifer by delivering Columbia Basin Project surface water supply, via the East Low Canal to additional farmland. Widening of the existing canal and construction of seven additional parallel siphons was chosen as the best alternative. This paper will discuss the construction and coordination challenges that were encountered throughout the placement of (4) 176-in. and (3) 156-in. inner diameter cast-in-place reinforced concrete siphons. Lessons learned on the first contract of siphons were immediately implemented for subsequent concrete placements and contracts. Some of the more significant changes were modifications to specialized formwork and vibratory methods, creative concrete mix designs with varying slump, placement sequencing and cure time, and coordination between different entities.

The Central Arizona Project (CAP) operates and maintains three (3) 21-foot diameter prestressed concrete non-cylinder pipes (PCP) as part of the aqueduct system that delivers almost 2 billion gallons of Colorado River water per day, to Maricopa, Pinal, and Pima Counties in central and southern Arizona. The water is delivered to municipalities, industries, Native American Communities, and agricultural users; over 5 million people (more than 80% of the population of Arizona) are provided water by the aqueduct system. The system traverses rugged mountains, desolate deserts, and highly populated urban areas as it conveys water from Lake Havasu at the western edge of the state to the southern boundary of the San Xavier Indian Reservation south of Tucson. The almost 350 mi long aqueduct system is composed of about 300 miles of open channel canals, about 10 mi of tunnels, and roughly 40 mi of pipelines; 14 pumping plants along the system provide the required lift to raise the water almost 3,000 ft from the lake to the final operating reservoir. The three large diameter pre-stressed concrete pipelines installed in the late 1970s have experienced pre-stressing wire breaks and have been repaired several times since the early 1990s; the wires have broken primarily due to defects in the wire. To better understand the current maintenance practices and determine if different or additional maintenance practices should be undertaken, a reliability centered maintenance workshop (RCM) was conducted on one of the pipelines, the Jackrabbit Wash Siphon. Items evaluated and discussed in the RCM included operating criteria of the pipeline, initial fabrication and construction of the pipeline, reviews of previous repairs and their condition, what triggered those repairs, current maintenance activities and condition assessment practices, documenting potential failure modes and the consequences, and what should CAP do going forward for maintenance of all three pipelines. The RCM concluded with a reliability centered design workshop (RCD) evaluating several repair options for the Jackrabbit Wash pipeline, should the need arise. This paper discusses the RCM/RCD Workshop conducted by the reliability engineering department at CAP and the subsequent results for the three large diameter prestressed concrete pipes, or inverted-siphons, which carry water beneath typically dry riverbeds: the Centennial Wash Siphon, the Jackrabbit Wash Siphon, and the Hassayampa River Siphon.

Sanitary sewer pipelines, like any other assets, have deteriorated over time and require renewal and replacement (R and R). U.S. Environmental Protection Agency (USEPA) estimates that $271 billion is needed for wastewater infrastructure over the next 25 years. Conventional replacement of underground utilities, especially sanitary sewers, uses open-cut excavation methods, which involves social costs, particularly in urban areas. The social costs include inconvenience to the general public and damage to surrounding existing structures. These costs become more important as the public awareness grows with needs to conserve and protect our environment and maintaining quality of life. The open-cut pipeline replacement (OCPR) process includes selection for a new route, surface and subsurface survey, engineering, planning and analysis, trench excavation, foundation and bedding, placing a new pipe, embedment, and backfill with compaction with select soil, and reinstatement of the ground surface The objective of this paper is to present a framework for evaluation of social costs of OCPR and to identify the influencing factors impacting these costs. A case study is used to study and identify the potential social cost factors. It was found that cost of fuel for detour roads, detour delay, and pavement restoration costs were the major cost driving factors. It can be concluded that social costs’ evaluation is an essential element when considering sustainable R and R of underground infrastructure. Project owners, decision makers, and contractors commonly take into consideration the construction costs only, and sometimes overlook the social cost aspects while calculating the total project costs. This framework can be utilized to analyze social costs of OCPR in sanitary sewers for different project and site conditions.

The Orange County Water District (OCWD) and the Orange County Sanitation District (OCSD) are partners in the groundwater replenishment system (GWRS) project, an innovative, award-winning water supply program to maximize local resources. The GWRS project provides an industry-leading example of how utilities can repurpose aging infrastructure into new services, extending its useful life and saving valuable financial and environmental resources. The GWRS final expansion project is currently underway. A critical component of the $292 million expansion is the repurposing of 15,750 linear feet (LF) of abandoned 66-in. reinforced concrete pipe (RCP) gravity sewer as a new force main to convey additional secondary effluent to the GWRS advanced water treatment plant, called the Plant 2 Secondary Effluent Pipeline. The existing abandoned sewer, constructed in 1957, runs parallel to the Santa Ana River and immediately adjacent to the river levee. Two other large diameter critical active sewer lines (120- and 84-in.) lie in close proximity within the same narrow easement. OCSD required the new force main to be capable of reverting back to serve as a gravity sewer during a major storm event. A condition assessment of the existing gravity sewer was performed which included laser scanning and the use of a virtual mandrel to determine the largest diameter pipe that could be inserted, thereby maximizing hydraulic capacity and minimizing annual pumping cost. The rehabilitation technique ultimately selected was to provide a fully structural liner with either fiber-reinforced polymer (FRP) or high-density polyethylene (HDPE). A steel pipe liner section was ultimately selected for the 300 LF siphon due to existing site constraints. This lining system will provide the desired minimum 50-year service life. This paper will provide an example to other utilities of how existing aging infrastructure can be successfully repurposed. Readers will learn how constructability and cost are used to select rehabilitation options and how to optimize performance of the finished pipeline by incorporating key elements into design.

Changes are common in construction projects and are primarily due to design changes or owner-directed changes. On average, 35% of projects experience at least one major change during construction. Changes can occur at any stage of the construction process, can be caused by a range of factors, and can have far reaching implications on project cost and schedule. Since most trenchless companies generally operate as subcontractors on construction projects, it is important to understand how these changes impact subcontract performance. Through an extensive review of literature and some court cases in the U.S., this paper analyzes some of the risks and protections afforded to trenchless subcontractors under contract law. A significant finding is that the prime contractor is not required by law to subcontract with the listed subcontractor if the work to be subcontracted has been changed substantially or deleted by a change order. Another finding is that a subcontractor can use the third-party beneficiary theory to recover damages from the owner even in the absence of contractual privity. Finally, subcontractors must be wary of exculpatory clauses in the contract that may undercut their efforts to recover damages. It is expedient and imperative for trenchless subcontractors to be aware of these legal provisions and how they can leverage them to protect their companies from loss.

Washington Suburban Sanitary Commission (WSSC Water), one of the largest users of carbon fiber reinforced polymer (CFRP) liners for large diameter pressure pipe, is considering expanding its use of FRP liners to include small diameter pressure pipes using the cured-in-place pipe (CIPP) technology. However, the lack of a well-established AWWA design standard for CIPP with strong analytical and experimental basis, similar to AWWA C305 developed for CFRP lining of large diameter pipe, has limited the use of CIPP to pilot projects and precludes applications at larger scale. The ASTM standards currently used for design of CIPP in the industry are known to have been originally developed for gravity pipe but are now increasingly used as Class IV (fully structural) liners for pipes with relatively high internal pressure without additional material qualification and design requirements. The number of CIPP products in the market increase continuously, and they differ in materials, architecture, susceptibility to imperfections, curing methods, etc., which cannot be evaluated on a uniform basis. Material test data are still being developed on a project-by-project basis. Having been involved in the decade long research program and in development of the AWWA Standard for design of CFRP liners for large diameter pipe, WSSC Water is currently evaluating the current state of the art of the CIPP technology in general, and some proposed CIPP products, for potential use in pressure pipe. The results generally indicate inadequacy of the current state of the art in addressing critical strength and stability design limit states (in both circumferential and longitudinal directions) according to WSSC Water design criteria and loads. Also, the evaluation demonstrated a deficiency in ensuring durability and reliability. This paper emphasizes the need for development of an AWWA standard for design of CIPP for small-diameter pressure pipe, and recommends additional design limit states, material qualification, and testing requirements that are not currently addressed by typical designs in the industry. Case studies on evaluation of CIPP for pilot projects will be discussed to demonstrate the need for more detailed design procedures and considerations which, when incorporated, will likely increase the use of CIPP for pressure pipe applications.

Following the evaluation of a 24-in. transmission line, downsizing was selected to maintain service to an Emergency Interconnection, the only service point along this section of pipe, while improving water quality by reducing age. This paper discusses the benefits of rehabilitating waterlines using sliplining technology and fusible polyvinyl chloride pipe (FPVCP) in an urban setting.

Corrugated metal pipe (CMP) in stormwater infrastructure deteriorates from exposure to corrosive and demanding conditions which can lead to failures that result in pipe collapse, sinkholes, and flooding. Replacement through open cut is costly and disruptive to traffic due to the need to excavate the damaged pipes and roadways. These challenges could be reduced using trenchless technologies. However, it is difficult to fit various trenchless techniques into a comprehensive approach to rehabilitation that can provide equivalent performance in stormwater. In this study, the City of San Antonio developed a proactive program to assess and select trenchless technologies that are suitable for the specific pipe/environmental conditions in the City. Four technologies were selected: cured-in place pipe (CIPP), sliplining, spray-on lining, and invert paving. A decision-making matrix was developed to provide decision-makers the flexibility to tailor optimal solutions for specific deficient structures. The matrix and rehabilitation methodology selection process were tested a Pilot Project that was conducted in September–October 2019 on four defective CMP segments, totaling 1,871 LF.

The research presented in this paper seeks to provide the CIPP industry with an option to eliminate the need for a safety perimeter and most personal protective equipment by destroying the VOC emissions at the liner termination point. Such a device would put the user on the leading edge of continually improving air quality and safety efforts in this valuable worldwide industry. This paper investigates VOC emissions in other industries and explores existing mitigation techniques created to meet the unique needs of those industries. Beyond a review of existing technologies, this paper outlines ongoing research at the Louisiana Tech University Trenchless Technology Center in Ruston, Louisiana, to provide the CIPP industry with a basis of design for a VOC mitigation device that will eliminate over 90% of the volatile organic compounds in the CIPP exhaust on the installation site at the termination manhole.

Pipe bursting is a trenchless replacement method for existing pipe with less surface disturbance than traditional open-cut construction. In some instances, potential ground movements caused by pipe bursting construction may lead to damage of surrounding structures. Pipe-swallowing is a pipe replacement technique that involves the replacement of a buried pipe with minimal surface disturbances. An experiment was performed in a 3.0 × 1.8 × 1.5 m test box to quantify ground movements during pipe-swallowing. An existing 300 mm diameter high-density polyethylene (HDPE) pipe was buried 1 m below the ground surface and replaced with a 300 mm diameter HDPE pipe. Pulling forces and the three-dimensional surface displacements associated with the pipe-swallowing operation were investigated. It is concluded that the pulling forces associated with pipe-swallowing were higher than with pipe-bursting, and almost no vertical or transverse displacements of the ground surface were observed during the tests. These data can be used as a database for specialists applying their operation in the field and related research into ground disturbance during pipe-swallowing.

Albany Department of Water & Water Supply maintains a combined sewer system containing many major components well over a century old. The Albany Water Board contracted a third-party inspection and assessment of approximately 2,600 LF of sewer within the Beaver Creek Combined Sewer District, a network that provides sanitary sewer and storm drainage for more than five square miles. Many sections of large diameter brick sewers were found to be obviously failing, including longitudinal fractures at pipe crowns running continuously along entire sewer sections, with bricks starting to fall out, indicating severe risk of failure and collapse. Stabilization and rehabilitation of these aging, failing structures was successfully completed with a centrifugally cast concrete pipe (CCCP) system, spincasting a fine aggregate composite concrete (FACC). Road closures and disruption to residents and businesses, including a hospital, were minimal. Work was completed on schedule, including the emergency change order, despite an unusually stormy season. The cost-effectiveness and quality of the repair was a huge success for Albany and is expected to add 50–75 years to the lifespan of these sewers.

The 7,600-foot long Colsman Tunnel, operated by the Southgate Sanitation District in Centennial, CO, is approximately 69-in. wide by 75-in. tall and is inconsistent in cross section due to the hand-tunneled nature of construction. The only manned access points are the east and west portals, with limited intermediate access through four existing ventilation shafts (18-to-24 in. in diameter) spaced approximately 1,600-ft apart. Flow from the District’s entire wastewater collection system (approximately 80,000 residents) is gathered and conveyed through the tunnel. Flows range up to 10 MGD and cannot be shutoff or bypassed. Based on the tunnel’s age and the continuous nature of the wastewater environment, the District became increasingly concerned with the reliability of the tunnel as even a partial collapse could result in a significant spill. Two manned entry inspections were carried out in 1981 and 1991, as well as a robotic inspection in 2015. The results of these assessments showed continuing degradation. The District was determined to take a proactive approach to extend the service life of the tunnel by fully rehabilitating or replacing it. The District determined that the lack of a clear methodology and complicated nature of the work warranted a collaborative approach and chose a Design-Build delivery method. The District selected the Garney Construction/Dewberry Engineers team to develop and execute a comprehensive solution to their high-risk facility. They also engaged Burns & McDonnell Engineering Company, Inc. as their Owners Engineer. What followed was an 18-month long process of developing and discarding conventional methodologies due to constructability, cost, risk, or public impact factors. This process ultimately led to the previously untried method of slip lining the 7600-foot tunnel with no intermediate access by continuously fusing a 48-inch HDPE pipe and pulling it in using a horizontal direction drilling rig through live flow. The Colsman project offers many unique insights and lessons learned on collaborative design-build delivery approach when undertaking a project with a clear goal but with uncertain feasibility or methodologies. The insights gained from this project include: structuring a Design Build team before the construction methodology(ies) are known; developing and vetting alternative approaches with input from the Owner; engaging specialty trades/resources to vet/refine/cost untried methodologies; maintaining Owner engagement and endorsement on design progression when the proposed unconventional construction techniques are in-progress and evolving; and shifting gears and achieving success when a selected construction approach proves to be unfeasible.

Insituform recently upgraded a pair of twin 90-in. equivalent diameter storm culverts near Beckley, West Virginia. The pipelines were located in a sensitive area. A waterfall was located upstream from the pipeline. Water to one pipeline had to be diverted while the other line was rehabbed. A trout stream was located downstream, which required that the contractor build a dam to keep water out of the stream. Each pipeline was approximately 200 ft long and ran directly underneath Interstate 77. The line was rehabbed using cured-in-place pipe (CIPP) to provide a fully structural, 50-year engineered design life. The CIPP was impregnated with resin and installed using an over-the-hole (OTH) method. This paper and presentation will cover project planning and engineering and an overview of the specialized impregnation and installation processes.

Industrial rehabilitation projects require special solutions. A paper plant in the Charleston, South Carolina, area had 42-in. pressure pipeline that had fully deteriorated and required rehabilitation. The original pipe was a series of ductile iron process sewer pipes running approximately 872 linear feet. Holes and voids had become visible, showing its deteriorated state and putting the plant’s crucial operations at severe risk. The solution chosen was a fiber-reinforced, polyurethane-coated CIPP tube with epoxy resin. The project was unique in that it had three 45-degree bends and three 22-degree bends, requiring a precise installation and quality engineered lining products. The crew successfully lined through the bends in the 750 LF shot. The jobsite was also within 100 yards of the Cooper River in Charleston, South Carolina. The system passed pressure tests and the system was back in operation by the client’s requested deadline, ensuring that any expensive downtime was eliminated, and structurally restoring their pipelines with an AWWA Class IV solution that was able to handle the operating pressures.

The Southside 120-In. Wastewater Interceptor Rehabilitation project includes sliplining 11,600 linear feet of 120-in. reinforced concrete pipe (RCP) with 110-in. fiber reinforced polymer mortar pipe. The project also includes internal point repairs on the parallel 72-in. reinforced concrete pipe and cured-in-place rehabilitation for over 800 linear feet of 42- to 54-in. reinforced concrete pipe. Construction for the Southside 120-In. Wastewater Interceptor Rehabilitation project began in November 2018 and will continue until December 2020. This presentation will focus on construction challenges like flow diversions, working in the 100 year floodplain, excavation and shoring up to 50 ft deep, sliplining through horizontal curves, cured-in-place rehabilitation underneath a creek, and grouting the annulus space after sliplining. The presentation will discuss how the owner, engineer, and contractor collaborated during construction to develop cost effective solutions. The presentation will also include numerous up to date construction photos to illustrate the lessons learned and sliplining process for large diameter wastewater rehabilitation.

In 2013, the City of Fort Worth, Texas, installed approximately 1,000 LF of machine spiral wound PVC liner pipe for the structural rehabilitation of a 48-in. × 42-in. stone arch storm drain. Open-cut construction was not feasible due to the cost and impact to adjacent utilities and infrastructure in the Commercial Business District of downtown Fort Worth. This was the first application for this technology on a storm drain in the City. BGE, Inc. developed construction plans and specifications for a 50-year design life of the rehabilitated pipe. Three in-situ construction methods were prequalified: (1) machine spiral wound poly (vinyl chloride) (PVC) liner pipe; (2) cured-in-place thermosetting resin sewer piping systems (CIPP); and (3) structural geopolymer lining system. In August 2018, the City performed a CCTV pipe inspection of the rehabilitated section. This paper discusses prequalification of construction methods and contractors, review of the performance of the product after five years post-installation, and evaluation of the current state-of-the-art trenchless rehabilitation methods including those not considered or available in 2013.

When it comes to linear conveyance/collection infrastructure, advances in technology continue to push the limits on what is possible and shape the public’s perception on what is acceptable. This has never been truer than in the tunneling and trenchless technology industry today. Significant advances have made tunneling possible in just about every geologic condition. Where once a body of water, groundwater, a building, topography, or difficult ground may have dictated an alternate alignment, advances in equipment, and monitoring now frequently allow trenchless applications to be installed in a variety of situations. Boundaries are continually being pushed and new technologies have allowed trenchless applications to be installed where never thought possible. Many utility owners are realizing they have an expanding arsenal of options at their disposal to install key infrastructure while minimizing disruptions to the general public. It is not uncommon for linear projects to frequently cross multiple socio-economic boundaries where stakeholders may have competing interests. For an example, one end of the alignment may involve commercial districts that prefer disruptions outside of daylight hours, whereas the other end may involve residential stakeholders that protest those same hours. Trenchless alternatives not only provide a possible solution for these competing interests, but they can also solve many other logistical issues when working in urban environments. This paper will address the viability of available trenchless construction methods and provide a couple examples of how communities are turning toward innovative tunneling and other trenchless methods to improve the quality of life for their stakeholders and communities.

The Northeast Interceptor services approximately 2,300 ha (5,685 acres) of land in the northeast quadrant of the City of Winnipeg (Manitoba, Canada). The 1,800 mm (72”) Interceptor crosses the Red River using a multiple-barrel inverted steel siphon configuration prior to it’s final leg before reaching the City’s largest wastewater treatment plant. The original siphon crossing, built in 1971, was at capacity during large wet weather events and required additional capacity to meet development plans and reduce upstream basement flooding risk. Thus, plans were developed to install an additional siphon. The size and construction methodology for the river crossing evolved through both the design and construction of the project. Originally starting life as a 600 mm (24”) horizontal directional drill crossing, system hydraulic requirements dictated the installation of a larger 900 to 1200 mm (36” to 48”) crossing to meet the desired design objectives. Due to the geotechnical, geometric, and surface use constraints, a 900 mm (36”) microtunnelled crossing was tendered. To facilitate microtunnelling through underlying limestone bedrock in an area where external access is extremely limited, the contractor (Ward and Burke Microtunnelling) opted to install a single pass 1200 mm (48”) siphon, increasing the capacity of the new crossing. Further changes to the project were proposed by the contractor and to an extent accepted by the project team. They included a vertically curved microtunnelling drive, eliminating the need to construct shafts within the underlying limestone aquifer, changes to the chamber designs to suit their preferred construction methods, and an alternative connection configuration to reduce tie-in risks. The challenge, as with any contractor driven design change, is to primarily ensure the original design intent and functionality of the project is not compromised. Secondarily, where construction risks have been shifted to other portions of the work, one must ensure they are of an acceptable magnitude and/or have been sufficiently mitigated. While this paper discusses the project as a whole, it primarily focuses on the evolution of the crossing design from inception to completion of construction. Managing design changes during construction is a critical component to any large capital project. This paper details AECOM’s efforts to manage proposed changes during construction, complete with a lessons learned and recommendations for future complex tunneling projects.

In accordance with a federal consent decree, citizens energy group is implementing a long-term control plan to address combined sewer overflows (CSOs) in Indianapolis. Included in the “DigIndy” plan are provisions for a series of CSO diversion structures, consolidation sewers, drop shafts, and a 44.8-km long network of six 5.4-m diameter tunnels. Beginning near the Indiana State Fairgrounds on the north, and ending on the south side of Indianapolis, DigIndy is the largest public works project in the city’s history. The tunnel system will capture up to 97% of CSOs along six Indianapolis waterways, reducing overflows to less than four per year, the maximum allowed by the U.S. Environmental Protection Agency (EPA). The final segment of the system is pleasant run deep tunnel, a 11,970-m long tunnel. Final planning optimized the conceptual design to achieve CSO capture objectives while eliminating expensive components and saving millions of dollars. After the elimination of several drop shafts from the original plan, final design included identifying potential revised locations of drop shafts. The project design faced challenges of construction in an urban environment around numerous utilities. Sizes of the near surface consolidation sewers range from 61- to 274-cm and are planned to be installed through various construction methods including traditional open cut and trenchless bore and jack. Outreach with city stakeholders and land owners of future developments for municipal and private projects led to relocations of shafts including a large diameter intermediate shaft. Citizens and the design team continued to optimize the tunnel alignment and near surface components to minimize consolidation sewer lengths. Recently, the collection system model was expanded, leading to updated flow data resulting in investigation of additional cost savings.

The crossing of Highway IH-69 with the City of Houston’s 108-in. water line presented unique design and construction issues. The tunnel design, which spans a major overpass, has a length of 1,150 LF with a primary liner diameter of 135-in. Along with the length, poor soil conditions posed major challenges to completing a successful installation. The soil conditions vary from full face of clay on the west, a full face of sand along the bore, to a mixed face consisting of clay and sand on the east. A 400-foot section of the drive showed coarse non-cohesive soils under the water table. This unstable material creates significant risk to the overpass structure and safe tunnel construction. The tunnel methods considered to successfully complete the crossing included soil stabilization with chemical grout coupled with a tunnel boring machine (TBM) with face closure abilities, or utilization of a pressurized face TBM. This tunnel diameter presents difficulties in selecting the means and methods of construction as it falls in the grey area defining the advantages between pipe jacking or building the tunnel primary liner in ring sets. During construction, the contractor proposed installing the portion under the bridge by open cut instead of tunneling. This method was evaluated but sidelined, as it was not perceived to reduce risk. Ultimately, the selected construction method consisted of using an earth pressure balance machine with jacked casing for the entire tunnel limits. Tunnel construction began in January 2020 and is past the IH-69 ROW as of early March.

Trenchless technologies are becoming more and more prevalent for pipeline installations; however, they are often far more risky than open cut installations due to the significance of the crossings and the uncertainty of underground utilities and conditions. Railroad tracks are typically crossed via trenchless methods and they are high risk crossings. Engineers perform due diligence, evaluate the pipeline corridors, design the trenchless installations, and then must rely on qualified Contractors to perform the trenchless installations successfully, using their expertise, means and methods, equipment-specific parameters, and best judgement during construction. The Florida East Coast Railway (FEC) is a Class II regional railroad that owns 351-mi of tracks extending from Jacksonville south to Miami, Florida. It connects to the national railway system in Jacksonville, Florida, to moving cargo to and from this location. It is the exclusive provider for PortMiami, Port Everglades, and the Port of Palm Beach, Florida. Recently, additional railroad tracks were run in parallel to the FEC corridor, for the Brightline All Aboard Florida project which now moves cargo and freight and people from central and south Florida. This paper will discuss both horizontal directional drilling (HDD) and jack and bore (J&B) methods of construction for four crossings of the FEC Railroad including: (1) identifying engineering due-diligence and design steps; (2) preliminary evaluations for trenchless methods of construction; (3) providing suggestions for items to document and monitor; (4) providing recommendations for a successfully completed trenchless installation; and (5) discussing potential risks of failure and recovery options.

This paper presents a case history of an HDD construction project with 50 feet of elevation difference between entry and exit locations. This paper will present pre-construction challenges, present lessons learned during construction, and suggest future design strategies to mitigate the challenges encountered during this project. This HDD project involved installation of approximately 500 ft of new 16-in. diameter HDPE water transmission line. The HDD bore started in a field on the low side of a 2-lane state highway, went under a gas line in the near shoulder of the highway, and started the new water line with a tie-in to the existing water line in the far lane of the highway. From the point of tie-in to the existing system, the HDD alignment traversed up-slope and crossed under a ditch line on the far side of the highway, a wetland mid-slope, and a rockery farther up-slope. Near the top of the slope, the HDD alignment went between two houses, followed a private drive, and exited into a cul-de-sac. The original design documents (designed by others) showed the HDD stopping midway up the private drive and transitioning to open cut at a 22.5-degree bend and thrust block. The contractor and the contractor’s engineer (the author) proposed post-award design modifications to deepen the alignment, lengthen the installation, and realign the installation. The alignment was deepened to provide greater depth of overburden to reduce the likelihood of inadvertent fluid returns, the installation was lengthened to eliminate the 22.5-degree bend and thrust block in a private driveway, and the alignment was moved laterally to avoid another private driveway that bisected the field at the HDD entry side. During construction there were unexpected challenges. These challenges included: Drilling fluid was lost to the surface in the wetland area due to the presence of springs that fed the wetland, there were steering challenges because of loose soil at the vertical curve to turn into the cul-de-sac, and there were areas of borehole collapse. Based on these construction challenges, the design strategies that will be discussed include communicating construction concerns and design limitations prior to construction, discussing and agreeing on contingency plans prior to construction, and the importance of obtaining permits from key stakeholders during design.

With origins in the oil and gas industry, horizontal directional drilling (HDD) has become a popular trenchless technology for installing underground utility lines in urban areas with minimal damage to the existing infrastructures such as roadways. However, the surface settlement might occur due to ground loss during the installation of pipe depending on the size and type of pipe, diameter of borehole, and soil type. While studies have reported issues due to HDD installation in regard of borehole collapse, few studies have mentioned about the surface settlement. Numerical simulation, especially finite element analysis, is often used as an effective method to minimize heave and subsidence induced damage and to improve HDD operation. The present study considers investigating the effect of different soil types; its cohesion, friction angle, modulus of elasticity, Poisson’s ratio, and the borehole size in regard to surface settlement in a numerical environment. With a view to selecting an optimal depth for safe installation and least surface settlement, the paper investigates both sandy and clay soil conditions with different construction depth and different pipe sizes. The results show that cohesion and cover depth have a large influence on ground settlement whereas friction angle and modulus of elasticity have relatively smaller effect. The study also discusses the stress redistribution in soil due to the arching effect. During the study, the settlement was considered as high risk when it reached a value of 0.5 in. while 0.1 in. settlement was reported as safe.

The Robertson Umbenhauer Water Treatment Plant referred to as the canal water treatment is over 75 years old and is in downtown El Paso. The plant is wedged between the Rio Grande River and the BNSF railyard. The railyard is over 100 years old, making infrastructure improvements near the plant challenging. To address aging infrastructure, El Paso Water wanted to replace existing transmission lines from the plant and build a new pump station. To mitigate risk, El Paso Water elected to use a design/build delivery method on this project. To put the risk in perspective, the project required a 66” diameter, 570' long tunnel across 18 active tracks under the railyard. It also required a second 315' tunnel across a TxDoT roadway. To compound the complexity, the Border West highway project by TxDoT had overlapping traffic control with this project. To facilitate construction of both tunnels, a single large entry shaft was constructed within the railyard. This created its own set of challenges coordinating with railroad personnel for access, safety requirements, and storing material and equipment. Any excavation within the railyard had its own risk as the yard had several abandoned pipelines mixed in with active pipelines that had been installed over its 100-year life. The experience gained on this project can provide several lessons learned and some innovative ways to monitor and track settlement in congested and difficult work areas.

Eastern Municipal Water District (District) needed to increase the wastewater conveyance capabilities of the previously built-out historic commercial area of Old Town Temecula, California. This special water district evaluated several different alignments and construction methods, but with the heavily commercial area being only three blocks wide and dozens long bounded by a freeway on one side and a river on the other, very few options were viable. Several different trenching methods were considered for increasing capacity of the existing collection system. Initially a 36-in. microtunneled casing and carrier pipe was considered, but ultimately replaced with a less expensive option: Auger Boring Method. Once construction started, however, every drive attempt failed. Construction was completed by greatly exceeding the accepted drive lengths of traditional jack-and-bore. This paper describes the tunneling method evaluations and the ultimately successful construction approach.

The Delft method has been broadly used for inadvertent return (IR) assessment in the horizontal directional drilling (HDD) industry. Prediction of the maximum allowable mud pressure, P_max, using the Delft equation requires multiple geotechnical parameters as inputs; however, this often poses challenges for practitioners. Since there is no apparent guideline established for the extraction of geotechnical parameters from site investigation data, the determination of Delft equation inputs becomes subjective, which ultimately results in the P_max prediction being unsystematic. Instead of converting site investigation data—such as the N-value from the standard penetration test (SPT)—into laboratory-based geotechnical parameters, a direct method of determination of P_max from the N-value is considered to be preferable. In this paper, a guideline for predicting P_max using the N-value is presented. Multiple correlations between N-values and geotechnical parameters have been evaluated, and these are introduced into Delft equation using a conservative margin of error.

The City of Houston retained Arcadis in 2012 for the design and construction oversight of a wastewater lift station elimination project. Two existing lift stations, Dairy Ashford Lift Station, and Harvest Moon Lift Station were to be eliminated by the construction of a new, larger capacity Harvest Moon lift station and approximately 4,200 linear feet of parallel sanitary sewer and force main. Five different methods were utilized for the construction of the flow diversion piping and lift station structure to accommodate the various right of way sizes, and to mitigate the adversity that was encountered during the construction phase. The success of this project is a direct result of the versatility of the project team, their ability to fashion the many hats of underground construction technologies, and to manage the ambiguity encountered throughout the project’s construction phase.

In 1996, the City of Novi, Michigan, permitted the development of a 10-acre parcel which included a sanitary sewer line that had been part of their system since 1986. Located in Oakland County, this installation was originally constructed using 10” PVC SDR 35 pipe at cover depths ranging from 10 to 12 ft. Below the pipe, the soil consistency was predominantly marl and peat. In 2005, the site was redeveloped with an additional 10-foot of fill added to the area above the sanitary sewer line. This surcharge load affected the flexible pipe and soil structure, as well as the peat and marl foundation below the pipe zone; the result was a failed pipeline. A new sanitary sewer line was proposed, designed, and bid as a conventional open trench excavation with over-excavation of the marl zone. Soil borings indicated the existence of a marl zone within the west end of the sewer elevation with a seven-foot layer marl zone over a five-foot layer of peat below. Moving to the east, the marl zone shifted to 2-ft below the sewer invert. The initial bid design required a foundation improvement of over-excavation of the marl, the addition of a geotextile wrap, and two to 7 ft of crushed stone in gradations of one to 3-in. This foundation improvement was required for pipeline support using conventional open-trench installation methods. The contractor value-engineered the project by identifying an alternative soil stabilization and installation method that was reviewed and approved by the engineer and the city. This paper outlines the soil stabilization and installation method used to replace the sanitary sewer. A cost comparison will be provided between the originally specified, conventional method and the trenchless soil stabilization with pilot tube method of guided boring (PTM) installation.