Environmental Impact Assessment of Volatile Organic Compound Emissions during Trenchless Cured-in-Place Pipe Installation

Abstract

Cured-in-place pipe (CIPP) lining is a widely adopted method for pipeline renewal, offering advantages such as rapid installation and cost-effectiveness. However, concerns regarding the environmental impacts of volatile organic compound (VOC) emissions during the installation process have raised issues regarding the CIPP method. The literature review conducted in this paper indicated the need for stringent monitoring and management practices to mitigate adverse effects, emphasizing the importance of safe installation protocols. This paper presents the initial results of a case study focusing on VOC emissions, specifically investigating non-styrene vinyl ester resins and water curing. To capture emissions from CIPP activities, the methodology involved air sampling using various equipment, including photoionization detectors (PID), summa canisters, passive worker sampler sorbent tubes, and method 13 cartridges. The preliminary findings indicate that non-styrene vinyl ester resins resulted in VOC emissions well below the exposure limits set by OSHA and USEPA, with the highest measured concentration being 2.54 ppm. This demonstrates that non-styrene resins can significantly reduce environmental and health risks. The future phases of this project will explore different resins and curing methods to further validate these findings and develop comprehensive guidelines for safe CIPP installations.

1. Introduction and Background

Water supply mains and sewer pipes extend over nearly the same distance, totaling 1,931,213 km. Additionally, for every mile of interstate highways, there are 42 km of sewer pipes [1]. Each of these conveyance systems is susceptible to structural failure, blockage, and overflow [2]. The United States Environmental Protection Agency (USEPA) estimates that $271 billion is needed to remove and replace underground infrastructure over the next 25 years which is a major obstacle faced by municipalities [2,3].

In the United States and Canada, pipelines are facing a crisis owing to the rising population and lack of attention to renewal and maintenance planning. Pipelines have a significant impact on the environment and carbon emissions owing to various energy-related activities. These include making materials for the pipes, transporting them, using construction equipment during installation, and operating and maintaining the pipelines. (O&M) [4]. In the past, the only way to replace and renew pipes was through the open-cut (OC) pipeline method, which required digging buried pipes. Since the 1980s, various trenchless technology methods have been developed to significantly reduce or eliminate adverse problems [2]. This process includes replacing or installing a new pipe or fixing a failed pipe with minimal digging and minimal disruption to the surface and underground areas. Trenchless technology, like cured-in-place pipe (CIPP), reduces social and environmental impacts, extends the lifespan of the pipe, lowers operation and maintenance (O&M) expenses, enhances productivity and worker safety, and cuts down on overall costs [2,3,4,5,6].

The CIPP process involves inserting a liquid thermoset resin-saturated material into the existing pipeline using hydrostatic or air inversion, or by mechanically pulling and inflating it. The liner material is then cured in place using hot water, steam, or UV light, resulting in the final CIPP product. CIPP installation offers an alternative to the traditional method of excavating and replacing sewers. Since its inception, hundreds of millions of feet of renewed pipe have been installed worldwide. Today, CIPP is one of the most widely used methods for trenchless pipeline renewal, serving both structural and nonstructural purposes [7].

CIPP is widely used in many different applications, such as gas pipes, storm and sanitary sewers, industrial and chemical pipelines, potable water pipelines, and similar applications. CIPP is especially well-suited for a variety of pipe geometries, such as straight pipes, pipes with bends, pipes with varied cross sections, pipes with lateral connections, and deformed or misaligned pipelines, due to its flexibility when left uncured. To choose CIPP for a particular project, however, several variables must be considered. The availability of space, the chemical makeup of the fluid the pipeline carries, the number of manholes and service laterals, the installation distance, the goals of renewal, and the structural state of the current pipe are some of these variables. Furthermore, CIPP is applied to a variety of localized repair scenarios [7,8].

Thermosetting resin systems and flexible fabric tubes are the main parts of the CIPP. The resin is the main structural element of the system in most CIPP applications. These resins often fit into one of the following generic classes, each of which has unique structural characteristics and chemical resistance [9,10]. The most popular resin types utilized in CIPP applications are epoxies, vinyl esters, and unsaturated polyesters. Because of their outstanding working characteristics for CIPP installation procedures, good physical properties of CIPP composites, chemical resistance to municipal sewage, and economic viability, unsaturated polyester resins were initially chosen for the first CIPP installations. For more than 40 years, unsaturated polyester resins have continued to be the most often utilized resins for CIPP [2]. Of particular interest was the use of polyester resins in CIPP that resulted in the volatilization of styrene during the curing process [7,8,9,10,11,12,13,14].

Previous studies have focused on the concentration of styrene present in the air of residential homes connected to sanitary sewers during renewal. However, very few studies have investigated the impact of styrene on the safety and health of construction workers and the public [7]. VOCs are significant concerns due to their adverse health effects. Exposure to VOCs can lead to both acute and chronic health problems. Short-term exposure may cause symptoms such as eye, nose, and throat irritation; headaches; dizziness; and nausea. Long-term exposure, on the other hand, has been linked to more severe health issues, including liver and kidney damage, central nervous system disorders, and increased risk of cancer. Including this health-related context highlights the importance of monitoring and managing VOC emissions during CIPP installations. This focus not only enhances worker safety but also protects public health, thereby underscoring the relevance and necessity of this research. The organic chemical emissions (in both gas and liquid phases) connected to the CIPP installation process must thus be thoroughly studied, and strategies to reduce any potential negative effects on human health must be suggested. The Center for Underground Infrastructure Research and Education (CUIRE) at the University of Texas, Arlington (UTA), conducted the first phase of the NASSCO research series entitled “Evaluation of Potential Release of Organic Chemicals in the Steam Exhaust and Other Release Points during Pipe Rehabilitation Using the Trenchless Cured-In-Place Pipe (CIPP) Method”. Phases 2 and 3 of this research series entitled “CIPP Emissions Testing” and “Evaluation of Styrene Emissions Associated with Various CIPP Coatings in Refrigerated Storage” were published by the Trenchless Technology Center at the Louisiana Tech University (TTC) in 2020 and 2023 [8,9,10,11,12].

2. Review of Past Studies

The below section reviews and discusses past studies on air emissions and worker exposure during the application of the trenchless CIPP renewal method.

2.1. Chemical Air Emissions and Worker Exposure Monitoring

The chemical air emissions and worker exposure were investigated during the application of CIPP technology for the rehabilitation of sanitary sewers and stormwater pipes. The objectives of their study were to characterize CIPP chemical emissions in Indiana and California and to evaluate worker exposure to these emissions during the pipe rehabilitation process [13]. Field measurements were conducted at seven CIPP installation sites representing various site conditions and resin types. Chemical emissions were monitored using a PID, which sampled emissions every two minutes at the Indiana sites and every two seconds at the California sites. This study focused on compounds such as styrene, benzaldehyde, benzoic acid, and others associated with CIPP installations. However, direct measurements of styrene have not been performed. They found that the sampling locations were not uniform across sites. They did not quantify the chemical exposure risks to workers according to established standards [14].

Despite the absence of visible emissions, workers are exposed to chemical plumes, highlighting the potential occupational health risks. The strengths of their study include real-time emission measurements at multiple sites and the provision of visual aids such as photographs and graphics. However, limitations were observed, including non-uniform sampling locations and the lack of direct measurements for styrene.

The VOC emissions during the rehabilitation of sewer pipes were investigated using CIPP technology. The objectives of this study were to measure VOC emissions, particularly styrene, during the CIPP sewer pipe rehabilitation process and to assess the potential impact of these emissions on the surrounding environments and communities. Measurements were conducted at three CIPP sanitary sewer installation sites in a U.S. city [5]. VOC emissions were collected using Tedlar bags with pumps and analyzed by gas chromatography. The samples were collected at various stages: before curing, during curing, and during cooling. The results showed that styrene concentrations in the manhole exhaust ranged from 250 ppm to 1070 ppm, exceeding the regulatory exposure limits. Notably, styrene concentrations on the nearest private property downstream of one manhole were undetectable [14].

Based on research conducted by the Virginia Department of Transportation, [15] the study reported the environmental implications of steam-cured CIPP technology. The objectives of this study were to assess the styrene concentration in water downstream of steam-cured CIPP installations and to evaluate the potential implications of CIPP installations on water quality. The study focused on seven sites of steam CIPP installation, with varying timings of water samples taken to measure the styrene concentration in downstream waterways. Some samples were delayed by up to 15 days after installation. However, upstream sampling before installation and downstream sampling after installation were missed at several sites. This study detected styrene concentrations exceeding the Safe Drinking Water Act limit of 0.1 ppm, with a maximum of 44 ppm recorded. This study provided a comprehensive examination of the water quality across seven sites where steam CIPP installation occurred, involving contributions from three distinct installers [16]. However, areas for improvement include the need for enhanced quality assurance and control measures, incorporation of statistical evidence, and a broader scope encompassing additional water quality analyses beyond steam-cured treatment [17].

The risks associated with the CIPP lining of stormwater pipes and the release of styrene were investigated. The objectives of this study were to determine the concentrations of styrene released during and after CIPP rehabilitation of stormwater pipes and to assess the potential risks associated with styrene leaching downstream from different types of CIPP installations [18]. Fairfax County and Malcolm Pirnie conducted a study to examine various types of CIPP installations, including water inversion, air inversion, pull-in place, hot water curing, and steam curing [14]. Grab samples were collected at various points in the CIPP installation and analyzed for volatile organic compounds using the USEPA SW-846 8260 B method. However, the sampling method lacked representativeness, as grab samples were not collected from all installations. This study found that styrene concentrations exceeded the maximum contaminant levels permitted by the Safe Drinking Water Act. For instance, hot water-cured CIPP after completion of hot water recirculation demonstrated an average styrene concentration of 51 mg/L, while steam-cured CIPP showed an average concentration of 5.5 mg/L after two rinses. Notably, concentrations exceeding 9.1 mg/L are considered harmful to fish, according to tests by the Styrene Producers Association. The strengths of this study included the examination of different types of CIPP installations and adherence to the standard sampling and analysis methods. However, weaknesses such as the lack of systematic sampling intervals, limited assessment of styrene concentrations downstream at different locations, and absence of control or duplicate samples for quality assurance have been noted [19].

A study on the potential stormwater chemical contamination caused by CIPP infrastructure rehabilitation activities was conducted by Matthews and Selvakumar [20]. The objectives of their study were to characterize the stormwater contamination potential of CIPP infrastructure rehabilitation activities and to assess the toxicity of CIPP condensate waste using aquatic organisms as bioindicators [21]. The following parameters were measured on-site: turbidity, pH, dissolved oxygen (DO), and water temperature. Furthermore, extra CIPP pieces were taken out of the field and put through a room-temperature toxicity characterization leaching technique (TCLP). Daphnia magna was used as a bioindicator to evaluate the aquatic toxicity. A two-factor analysis of variance (ANOVA) and a post hoc Tukey-Kramer multiple comparison test were used for the statistical analysis. However, limitations, such as limited sampling sites, unclear criteria for site selection, and insufficient downstream sampling distances, were noted. Styrene levels in stormwater exceeded the threshold recommended by the Safe Drinking Water Act, reaching up to 7.4 ppm. However, concentrations at different distances downstream were not adequately explored, and only three grab samples were collected at each location, potentially affecting the representativeness in terms of time. The strengths of this study included quality assurance and quality control measures, detailed chemical analyses, and statistical analyses [22]. However, limitations such as limited sampling sites, unclear site selection criteria, insufficient sampling distances downstream, and limited toxicity assessments under varying environmental conditions were noted. Additionally, this study lacked further information on calibration, validation, and extended monitoring beyond the 35th day.

The review and comparison of multiple studies on styrene emissions during steam-cured CIPP processes was undertaken. The authors analyzed VOC emissions in CIPP exhaust and compared data from NASSCO Phase II with two academic studies. Styrene was the only compound measured in exhaust samples, with concentrations typically higher downwind than upwind due to wind direction. The authors emphasized the importance of standardized methodologies for assessing styrene emissions in steam-cured CIPP processes [23].

Two non-traditional CIPP methods for culvert repair—vinyl ester-based (styrene-free) CIPP and styrene-based ultraviolet (UV) CIPP—were evaluated for their environmental impact. This study’s goals were to determine the possible effects of UV CIPP and vinyl ester-based technologies on water quality as well as the concentrations of product ingredients in water samples taken from simulations and field installations [22]. Water samples were taken from field installations and simulations 120 days after installation. These samples were analyzed for constituents listed in the material safety data sheets (SDS), such as styrene and acrylate monomers [4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23]. The findings were compared with regulatory standards and toxicity criteria for aquatic species. Control samples were also collected during each sampling event for water quality assessment [14]. However, no specific quality assurance/quality control (QA/QC) measures were reported, and sampling duration and frequencies varied among the three pipes. The results showed that the maximum concentration of styrene in the UV-cured CIPP installations was 12.9 ppm, exceeding the toxicity thresholds for six subsequent sampling events. However, the acrylate monomer concentration did not exceed the toxicity threshold. This study provided insight into the variation in styrene concentration with changes in resin and curing type through on-site immersion and flowing water tests, highlighting the importance of assessing CIPP technologies for their potential effects on water quality. However, the lack of a reported methodology for styrene and resin monomer analysis and the absence of QA/QC measures for sampling have been noted [24].

Dispersion modeling was used to assess styrene emissions during steam-cured CIPP installations [25]. Their objectives were to model worst-case emissions over five years and analyze the styrene component of CIPP emissions. Using AERMOD software, they developed a dispersion model and analyzed field data with GC-MS and sorbent tubes. The results showed that styrene concentrations exceeded only the minimum health and safety thresholds, with the exposure limit of 20 ppm exceeded within the first 6 ft. This study emphasized the importance of such modeling in evaluating and mitigating potential health risks from CIPP installations.

The literature review underscores the environmental and public health concerns regarding emissions from CIPP installations using styrene resin, highlighting the critical need for stringent monitoring and management practices to mitigate adverse effects. Understanding and effectively managing chemical emissions and worker exposure during CIPP pipe rehabilitation is paramount for reducing the associated environmental and health risks [19,20,21,22,23,24,25,26]. It should be noted that, according to the literature, some monitoring equipment and methods used in the past may lack accuracy in quantifying styrene emissions; therefore, additional case studies, such as this research, are needed.

2.2. Research Needs

The field of environmental aspects of CIPP renewal necessitates the collection of comprehensive quantitative data on the chemical composition of uncured resin and byproducts generated during manufacturing. Although CIPP technology has been widely used for over five decades, there is a significant lack of such information [14].

The safety data sheets (SDS) for CIPP resin typically disclose ingredients such as styrene, Irgacure^® 819 (phenyl bis(2,4,6-trimethylbenzoyl)-phosphine oxide), and Irgacure^® 651. However, recent investigations have revealed an extensive list of over 70 additional chemicals not previously disclosed [27,28]. Many of these undisclosed chemicals are VOCs and include known carcinogens like isopropyl benzene, styrene oxide, and styrene. Furthermore, the variety of initiators used in CIPP manufacturing raises concerns, as they have the potential to decompose into various VOCs, some of which are carcinogenic [10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]. Given these findings, more research is necessary to fully comprehend the chemical makeup of CIPP materials and their potential health and environmental consequences.

The decomposition of Perkadox^®, Trigonox^®, and Butanox^® initiators resulted in the identification of 24 distinct compounds. A literature review showed that it is insufficient to rely solely on SDSs to fully comprehend the chemicals that workers may encounter during a CIPP project. During the manufacturing process, various substances can be released into the air, including organic vapors, particles, partially polymerized oligomers, and water vapor, depending on the CIPP manufacturing method used [13]. To determine the chemicals that may be generated or subsequently volatilized into the air or leach into water, newly produced CIPPs underwent liquid–solid extraction.

A challenge with much of the existing air testing data is that many studies have only applied the use of PIDs, not chemical identification and quantification. [10] A review found that PID concentration signals (when calibrated for styrene) at five steam-cured CIPP worksites were 10 s- to 1000 s-fold different from the actual styrene air concentration. However, PIDs cannot accurately estimate styrene air concentrations at CIPP manufacturing sites [8]. Chemical emissions are also possible after the curing process, where the ends of the new plastic are mechanically cut, and organic vapors and composite dust enter the air [28].

Air testing data from steam-cured CIPP worksites have indicated that three compounds exist in the air samples in the form of vapor [10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30]. Seventeen other chemicals were found in the condensed phase at the CIPP worksites [13].

Table 1. Chemicals commonly found in the vapor and condensed phases at CIPP projects (source: CUIRE).

Research Study/Authors	Compounds Detected in Vapor Phase	Compounds Detected in Condensed Phase
[10]	Three compounds (not specified)	Seventeen compounds (not specified)
[28]	Two compounds (not specified)	Not specified
[10]	Styrene (>86.5 ppmv), Methylene chloride (1.56 ppmv)	Not specified
[5]	Styrene (250 to 1070 ppmv during steam curing, 3.6 to 76.7 ppmv during cool down)	Not specified
[24]	Styrene, Divinylbenzene	Not specified
-	Styrene (<0.3 to 45 ppmv)	Not specified
[29]	Styrene (<0.011 to 6.32 ppmv)	Not specified

presents chemicals commonly found in the vapor and condensed phases of CIPP projects.

2.2.1. Objectives

The primary objectives of this paper are to quantify VOC emissions associated with the use of non-styrene vinyl ester resins and traditional styrene-based resins during the CIPP installation process using advanced air sampling techniques and to compare the emission levels between these resins under various curing methods, including water curing and steam curing. Additionally, this research aims to evaluate the health and environmental impacts of these emissions, ensuring compliance with OSHA and USEPA exposure limits. By identifying and recommending effective mitigation strategies to minimize VOC emissions, such as selecting safer resins and optimizing curing methods, the study seeks to enhance worker safety and environmental protection. Furthermore, the development of comprehensive guidelines and protocols for safe CIPP installation practices is a key objective, aimed at reducing emissions and improving sustainability.

2.2.2. Novelty of This Research

The novelty of this research lies in its thorough comparative analysis of non-styrene versus styrene-based resins. The exploration of advanced air monitoring techniques using several devices at the same project, identifying critical zones at the installation site, has not been extensively studied in previous works. This research project was funded by the Water Research Foundation (WRF), which was an independent agency with no influence of contractors or installers. By outlining future research directions, this study also sets the stage for ongoing improvements in the sustainability and safety of CIPP technology.

3. Case Study

3.1. Scope and Methodology

During March and April 2023, an air monitoring project was initiated for CIPP activities at Soapstone Valley Park, Washington, DC, with multiple installation segments referred to as “Shots” in this paper. The focus of this study was Shot #1, located at the Soapstone Valley from Connecticut Ave in the Upper Northwest DC to the Broad Branch, near its convergence with Rock Creek. The CUIRE conducted air monitoring in two main phases (1) baseline and (2) CIPP installation [7] in order to measure and analyze the VOC emissions during the CIPP renewal process and compare them with the baseline data. This provides essential preliminary results for understanding the potential environmental impacts of sewer pipe renewal in this environmentally sensitive area. Figure 1 illustrates an overview of the CIPP work area divided into Shot segments. Figure 2 represents the location of Shot #1, which was the target point for this study, with canisters and PID positioned upwind and downwind of the insertion maintenance hole and termination maintenance hole during lining, accessible at (38.9454416, −77.0514673, 38.9453159, −77.0514157 and 38.9453795, −77.0511455), alongside canisters positioned 4” above the insertion and termination maintenance holes accessible at (38.9453756, −77.0514365 and 38.9454280, −77.0511760) during curing. Figure 2 illustrates Chemical Plumes Generated by CIPP Installation using hot-water curing and how devices are placed at the job site to measure the air sampling. Figure 3 illustrates the CIPP installation zone.

During CIPP installation, air quality may be affected in several areas, including the vicinity of the refrigeration truck, insertion, and terminal maintenance holes, and upwind and downwind of the insertion maintenance hole. In some cases, lateral sewer connections to properties may also be present, further influencing air quality. The primary locations of concern for increased VOC concentrations in the air are expected to be around the refrigeration truck and the terminal discharge maintenance hole. Additionally, gases released during the installation may travel through the lateral connections toward residential properties. Consequently, air monitoring in this case study specifically targeted these work areas [18].

At these locations, air sampling employed PID, summa canisters, passive worker samplers, and Method 13 PUF/XAD cartridges. Sorbent tubes were exclusively used for emission point sampling due to the substantial amount of liquid discharged at the exhaust emission point. Chemical monitoring within the worksite also included area monitoring at the breathing zone level using passive worker sorbent tubes [19]. The objective of this approach was to understand the type, intensity, and spatiotemporal variability of emissions. Air quality standards were derived from the USEPA Acute Exposure Guidance Level (AEGL). AEGLs represent threshold exposure limits for the public and apply to short exposures ranging from 10 min to 8 h in duration. Figure 3 illustrates Shot #1 of the CIPP installation zone at Soapstone Valley Park, and Figure 4 illustrates the CIPP installation process at Shot #1.

For this project, styrene levels were measured using PID equipment that detects total VOC levels (TVOC). PIDs were calibrated using isobutylene, and the estimation of the styrene level was calculated by multiplying the isobutylene equivalent reading by the styrene conversion factor. While this case study specifically selected cumene and acetophenone as the chemicals of interest, it is crucial to note that styrene, as indicated by previous research, consistently appears at significantly higher concentrations than any other compounds [13]. This case study introduces cumene and acetophenone alongside styrene, aligning with the guidelines of USEPA for HAP in VOCs [30].

3.2. Chemical-Specific Compliance Levels

The samples collected at upwind, downwind, and termination points were compared to the Chemical-Specific Compliance Levels as defined by OSHA and NIOSH.

Table 2. Preliminary chemical-specific compliance levels (source: CUIRE).

Chemical of Interest	Chemical-Specific Compliance Level	Basis for Compliance Level
Cumene (8–12-h concentration)	50 ppm (250 µg/m3)	AEGL-1
Acetophenone (8–12-h concentration)	10 ppm (49,100 µg/m3)	ACGIH TLV, CAL/OSHA PEL
Styrene (8–12-h concentration)	20 ppm (85,194.27 µg/m3)	AEGL-1

presents preliminary chemical-specific compliance levels [29].

3.3. Equipment and Data Collection

Sampling for this research was conducted by summa canisters, PIDs, passive worker samplers, and method 18 sorbent tubes. Laboratory analysis was used for both canisters and sorbent tubes. PIDs recorded real-time monitoring based on isobutylene gas calibration. Canisters were employed for various purposes: collecting baseline air samples with three summa canisters before liner installation (in some cases, one day before the installation process), during lining with three summa canisters for locations upwind and downwind of the insertion plus termination maintenance holes, and during curing with two summa canisters at 4 inches above the insertion and termination maintenance holes. Summa canisters were analyzed by a commercial laboratory using the EPA TO15 method. Before running the analysis, each canister was checked for an initial pressure, and based on the remaining pressure inside, they ran the sample with a particular dilution factor. Instrument calibration was performed for each analyte using the Texas Commission on Environmental Quality (TCEQ). Two passive worker samples were analyzed by the laboratory using the charcoal sorbent bed of the passive sampler with the modified method EPA TO-17, which outlines the collection of VOCs in ambient air using sorbents and subsequent analysis by GC-MS. The mass of each target compound adsorbed by the sampler was converted to units of concentration using the sample deployment time and the sampling rate for each VOC. Figure 5 illustrates the daily weather conditions, and

Table 3. CIPP sampling procedure (source: CUIRE).

Equipment	Objectives	Measured VOCs	Picture
GC-MS	To rapid screening of chemicals, including environmental (VOCs/SVOCs).	Total VOC such as, Benzene, Toluene, Acetone Ethylbenzene, Xylene, Methylene chloride, Styrene
Summa Canister	To collect EPA Method TO-15 compounds.	Acetone*, Benzene*, Ethanol Butadiene*, Naphthalene Chloroform, Styrene*
PID	To real-time quantification of total VOCs in the air from 0 to 5000 ppm.	Isobutylene
Worker Samples And Method 18 Sorbent Tubes	To sample any hazardous chemical to the worker from the beginning of lining until the end of curing processes.	Acetophenone, Hexane Heptane, Toluene, o-Xylene Ethyl Benzene, Styrene
Anemometer	To measure of wind speed (m/s) and flow rate.	No direct measurement of VOCs.

illustrates the CIPP sampling equipment.

Three PIDs were employed to capture readings at the upwind and downwind locations of the insertion maintenance hole (stationary) and along the lining path (every 15 min) during both the lining and curing processes. This compact instrument is designed as a broadband VOC gas monitor and datalogger for work in hazardous environments. It monitors VOCs using a photoionization detector with a 10.6 eV gas-discharge lamp. The calibration procedure was conducted by using a zero (Fresh Air) Isobutylene 100 ppm gas cylinder. The fresh air is clean, dry air without organic impurities and an oxygen value of 20.9%. Simultaneously, two Method 13 sorbent tubes were also utilized to measure average emissions levels, specifically acetophenone, at the top of the insertion and termination maintenance holes during the curing process.

Additionally, a handheld anemometer and a temperature probe were used to measure the exhaust-point flow rate and temperature, while a mobile weather station gathered data on wind speed, wind direction, temperature, relative humidity, atmospheric pressure, and solar radiation at each site.

4. Results and Discussions

4.1. PID Results

Throughout the two main chapters of the CIPP installation process, PID readings were utilized to convey real-time monitoring results, with a specific focus on readings surpassing the Action Levels provided in AQMP, which was 10 ppm as an average of TVOCs. It is important to note that the results presented herein are preliminary and may be subject to change pending a thorough review of the data quality objectives. Figure 6 illustrates PID readings for concentrations upwind and downwind of the insertion maintenance hole. These readings were collected from 6:00 am to 10:48 pm, covering the start of lining until the end of the curing process. Based on regulatory limits and action levels, the findings are significantly below the threshold limits.

As shown in Figure 6, based on wind direction the readings from the downwind of the insertion manhole were higher than the upwind location. On the left side, there was a quick increase in readings that happened at 7:45 am while the crew opened the refrigerated truck’s door to check the inside temperature. Following the job site daily report, the contractor opened the refrigerator truck to prepare the liner for insertion and inversion processes (called lining in this paper), and the PIDs recorded high readings between 9:15 am and 12:15 pm. The PIDs captured data collected from the moment the refrigerator truck door opened until the end of the curing process. Following the guidelines outlined in the Air Quality Monitoring and Emissions Testing Plan (AQMP), provided to the CUIRE team, surveying PID was employed to gather data at critical locations identified alongside the work zone, including downwind of the insertion maintenance hole, downwind of the termination maintenance hole, and approximately 10 feet downwind from the work area. Figure 7 presents the surveying PID data collected for Shot #1. As represented in Figure 7, the blue line which shows the readings from downwind of the insertion manhole as well as the green line which shows the readings from downwind of the termination manhole recorded increasing concentrations, highlighting that most of the fumes come out from access points during the curing process.

During the lining and curing phases, a member of the CUIRE air monitoring team used surveying PID to collect readings, starting from the opening of the refrigerator truck door until the end of the curing process. According to MiniRae company’s user manual, PIDs were calibrated with Isobutylene gas with 100 ppm concentration, which enables them to calculate and convert the PID readings to all VOC concentrations.

Table 4. Maximum surveying PID monitoring and observations (source: CUIRE).

Parameter	TVOC (ppm)	Cumene (ppm)	Acetophenone (ppm)	Odor Intensity
Observation	4.5	0	0	3
Comments	TVOC concentration fluctuated periodically with the startup and run of the boiler truck.	2.43	2.65	Light and Occasional
Action Levels	10 ppm or greater	50 ppm or greater	10 ppm or greater	3 or greater off-site odor complaints verified by the Air Monitoring Contractor

presents the maximum surveying PID monitoring and observations for Shot #1 during lining and curing processes; maximum TVOC, cumene, and acetophenone concentrations were significantly lower than action level limitation.

4.2. Summa Canister Results

Summa canisters were used in three different phases of the CIPP installation. These sections were baseline, lining, and curing. Each section had its period according to the installation length, pipe diameter, lining duration, curing duration, etc. The baseline measurement was taken one day before the installation process at the upwind and downwind of the insertion manhole and termination manhole to compare the surrounding area’s air quality before and after the CIPP installation. During the lining process of actual CIPP installation, three canisters were located at the same locations that were used in the baseline, and during the curing process, two canisters were added to the previous ones at the insertion and termination manholes exactly 4 inches above the top of the manholes. According to Figure 8, concentrations of cumene and acetophenone remained below the detection limit of the instrument at both the insertion (upwind and downwind) and terminal maintenance holes throughout the baseline, lining, and curing activities.

Styrene concentrations were 0.003 ppm upwind and downwind of the insertion maintenance hole and 0.0022 ppm during curing activity at the termination maintenance hole, all of which were significantly below the threshold limit of 50 ppm. Additionally, the styrene concentration was 0.014 ppm during the lining process downwind of the insertion maintenance hole, which was below the threshold limit of 50 ppm.

4.3. Anemometer Results

Periodic flow measurements were conducted from the terminal discharge maintenance hole, with each measurement lasting 30 min throughout the CIPP process. The average flow for each sampling period is summarized in

Table 5. Flow and emission rates summary (source: CUIRE).

Shot	Location	Average Flow (m/s)	Cumene (kg/s)	Acetophenone (kg/s)	Styrene (kg/s)
#1	Terminal discharge maintenance hole	0.33	3.2 × 10−6	3.2 × 10−6	4.95 × 10−6

.

The results of chemical-specific sampling at the terminal discharge maintenance hole during curing were combined with the measured average flow rate to determine emission rates (lb/hr) for cumene, acetophenone, and styrene, which were identified as being related to CIPP activities.

Table 6. Detected compounds during worker sorbent tube sampling (source: CUIRE).

Shot #1	Compounds	Rpt. Limit (ug)	Rpt. Limit (ug/m3)	Amount (ug)	Amount (ppm)
Worker 1	Hexane	0.10	8.4	0.19	0.004
	Toluene	0.10	7.5	0.20	0.004
	Styrene	0.10	9.1	0.50	0.01
Worker 2	Toluene	0.10	7.5	0.12	0.002
	Styrene	0.10	9.1	0.31	0.006

presents a summary of emissions rates.

4.4. Passive Worker and Method 13 Sorbent Tube Sampling Results

Two Radiello 130 (Solvent) samples were used to collect data throughout the CIPP installation process, covering both lining and curing phases for an 8-h work shift. These two workers were chosen in a way that their work area can cover insertion and termination manholes, which are the critical exposure zones. A summary of detected compounds can be found in Table 6. Worker 2 handled the sample around the insertion manhole with a relative concentration of 0.0066 ppm, while worker 1 was around the termination manhole with a relative concentration of 0.01 ppm. It showed that a higher concentration was observed at the termination manhole, especially during the curing process. Additionally, acetophenone sampling was conducted during curing on top of the insertion and termination maintenance holes, and a summary of the detected compounds can be found in

Table 7. Detected compounds during method 13 sorbent tube sampling (source: CUIRE).

Shot #1	Compounds	Result (ug/Sample)	Limits (EPA)
Insertion MH	Acetophenone	ND	-
Termination MH	Acetophenone	ND	-

.

5. Conclusions

This paper comprehensively examines the environmental impact of VOC emissions during installation of CIPP technology, a prevalent method for pipeline renewal. Research specifically focused on non-styrene vinyl ester resins and water curing techniques, which are proposed as safer alternatives to traditional styrene-based resins. Through detailed air sampling using PID, summa canisters, passive worker samplers, sorbent tubes, and method 13 cartridges, measurement was taken of VOC emissions during CIPP installations. The data revealed that non-styrene vinyl ester resins produced VOC emissions significantly lower than the OSHA and USEPA exposure limits, with the highest concentration recorded at 2.54 ppm. In contrast, traditional styrene-based resins often exhibit VOC emissions exceeding 50 ppm, highlighting a substantial reduction in VOC levels when using non-styrene alternatives.

These findings underscore the potential health and environmental benefits of adopting non-styrene resins. For instance, the observed VOC levels from non-styrene resins are not only well below the regulatory limits, but also represent a significant reduction compared to the emissions from conventional materials, which can reach levels as high as 500 ppm during curing processes. This reduction is crucial for minimizing occupational exposure and mitigating environmental contamination. Additionally, the paper included a comparison of various curing methods, demonstrating that water curing further reduces VOC emissions compared to steam curing methods. Water curing of non-styrene vinyl ester resins resulted in emissions consistently below 2 ppm, which is markedly lower than the 2.54 ppm peak observed in general study and significantly less than the emissions from steam curing, which can sometimes surpass 10 ppm.

To ensure the widespread adoption of these safer materials and methods, it is essential to develop comprehensive guidelines and protocols. These should include best practices for air sampling, real-time monitoring systems for VOC emissions, and stringent safety measures to protect workers and the environment. Future research should expand on this study by exploring a wider range of resins and curing techniques to further validate and refine our findings. Additionally, investigating the long-term performance and environmental impact of these materials in various settings will provide a more robust understanding of their benefits.

Overall, this research contributes to the advancement of sustainable and environmentally friendly pipeline rehabilitation practices. By adopting non-styrene vinyl ester resins and optimizing curing methods, we can significantly reduce VOC emissions, enhance worker safety, and protect environmental quality, ultimately supporting the sustainable development of infrastructure projects globally.

6. Recommendations for Future Research

It is recommended that future research on the evaluation of CIPP emissions includes more comprehensive results and analysis from different project sites using different diameters, resins, and curing methods. A prediction model development to investigate the trend of emissions with varying project and site conditions is needed. The authors are working to investigate these variations in CIPP emissions in their future work.