Chemicals Released from in-situ Pipe Lining Installations: Current Practices and Water Quality Impacts

Kyungyeon Ra, Purdue University

Abstract

In-situ pipe repair technologies such as cured-in-place-pipe (CIPP) and spray-on lining can rehabilitate damaged sanitary sewer, storm sewer, and drinking water pipes. The technologies are selected because of their low-cost and ease of installation. However, utilities, regulators, and health officials have raised environmental, occupational, and public health concerns regarding chemical emissions into water and air. The overall goal of this thesis was to identify the potential for and magnitude of chemical release for in-situ pipe lining installations, and recommend actions that can limit these impacts. To achieve this goal three separate studies were conducted and are presented as three independent thesis chapters. In Chapter 1, a critical review of the available literature for CIPP technology was conducted. The study objectives were to: (1) compile and review CIPP-related surface water contamination incidents from publicly reported data; (2) analyze CIPP water quality impacts; and (3) evaluate current construction practices for CIPP installations as reported by 35 department of transportation (DOT) agencies in the United States. Surface water contamination caused by CIPP installations has been documented in 11 states due to the release of uncured resin, solvents, manufacturing byproducts, and wastes. Odor, fish kill, and drinking water supply contamination incidents have occurred. The few field- and bench-scale studies available show that a variety of VOCs and SVOCs can be released into water and leaching can occur for several months. Chemical release is influenced by formulation, installation, and environmental conditions. CIPP wastewater was acutely toxic to aquatic organisms. Additional studies are needed to develop evidence based construction and monitoring practices to minimize risks. The study described in Chapter 2 was conducted to identify the type and amount of chemicals present in new CIPPs. The study objectives were to (1) chemically extract and quantify compounds in uncured resin tubes and CIPPs for five installations in California, and (2) characterize CIPP visual, physical, and thermal characteristics. The steam-curing process was applied to styrene-based resin (pipes 1, 3, 4, and 5) and a non-styrene-based resin (pipe 2). Results showed that pipe 4 contained uncured resin, pipe 5 was blistered, and blister-liquid contained chemicals that had state water quality standards. A greater number and amount of chemical compounds were extracted from CIPPs using dichloromethane than with hexane, though some compounds were only detected in one solvent. When CIPPs were heated to 160°C, as much as 2.21 wt % was lost (pipe 2), while other pipes had less than 1.64 wt % loss. This weight loss was suspected to be attributed to volatile compound loss. Several compounds were extracted from CIPPs and included acetophenone, acetone, benzaldehyde, 4-tert-butylcyclohexanone, 4-tert-butylcyclohexanol, dibutyl phthalate, phenol, styrene, 1-tetradecanol, and tripropylene glycol diacrylate, Compounds associated with 69-81% of the total mass extracted by DCM and 92-94% of the total mass extracted by hexane remain unknown. Additional work is needed to understand how uncured resin formulations, installation, and environmental conditions influence new CIPP physical and thermal properties, as well as residual chemical loading. Additional work is also needed to predict chemical emission during or after installation. In Chapter 3, available chemical leaching and water quality impact literature for polymer-based spray-on liner storm sewer pipe installations was reviewed. Study objectives were to: (1) compile and review spray-on lining related surface water contamination incidents from publicly reported data; (2) analyze water quality impacts on spray-on liners; and (3) evaluate current construction practices for spray-on liner installations as reported by 35 DOT agencies in the United States. No scientific literature or media reports were found regarding spray-on liner water contamination incidents. Very limited information exists for chemical release from spray-on lining storm sewer installations and only one DOT investigation was found. Only three of 35 states provided construction guidance regarding spray-on liners, whereas most indicated they had no official guidance. Information was provided about the cement mortar (2 states) method followed by polyurethane (1 state), epoxy (1 state), and polyurea (1 state) lining method. For specifications, only one state required water testing before and after spray-on liner installations. The two other states did not require water quality monitoring nor include any information about minimizing water quality impacts. One state DOT required curtains to prevent overspray during spray-on liner installations. For an improved understanding of spray-on liner technology, additional work is needed to determine the compounds that could be released and their magnitude. Installation site monitoring practices and future research was recommended. As more information becomes available, specifications should again be upgraded. This thesis provides a better understanding of CIPP and spray-on liner as well as current construction practices, contaminant incidents, and potential water quality impacts. As information described in this thesis shows that additional studies are needed to better understand the differences in chemical composition of raw materials and chemicals/materials released from or left behind (inside the new liner). Information developed can be used to update existing construction specifications and outline future work. Additional work is recommended to develop evidenced-based construction specifications that can limit chemical emission, conduct testing to understand the range of chemical loading across and leaching from CIPPs, and implement findings into evidence-based construction specifications, CIPP integrity, and environmental monitoring protocols.

Degree

M.S.

Advisors

Whelton, Purdue University.

Subject Area

Environmental engineering|Civil engineering

COinS