2015 Progress Report: Evaluation of Lead Service Line Lining and Coating TechnologiesEPA Grant Number: R834865
Title: Evaluation of Lead Service Line Lining and Coating Technologies
Investigators: Adams, Craig D. , Cuppett, Jonathan , Peltier, Edward F. , Randtke, Stephen J. , Roberson, J. Alan
Current Investigators: Case, Traci L. , Adams, Craig D. , Peltier, Edward F. , Randtke, Stephen J. , Roberson, J. Alan
Institution: Water Research Foundation , American Water Works Association , University of Kansas , Utah State University
Current Institution: Water Research Foundation , American Water Works Association , University of Kansas
EPA Project Officer: Hiscock, Michael
Project Period: January 1, 2011 through December 31, 2016
Project Period Covered by this Report: January 3, 2015 through January 3,2016
Project Amount: $600,000
RFA: Advancing Public Health Protection through Water Infrastructure Sustainability (2009) RFA Text | Recipients Lists
Research Category: Drinking Water , Water
The objectives of this research project are to: (1) comprehensively evaluate lead service line (LSL) lining and coating technologies as alternatives to full or partial LSL replacement, and as a means of protecting and repairing both lead and copper service lines (CSLs); and (2) provide water utilities, engineering consultants, state regulators, consumers, and other interested parties with information and supporting documentation needed to make informed decisions regarding lining and coating of both LSLs and CSLs.
We evaluated technologies for lining or coating LSLs, identified issues decision makers should consider when lining or coating LSLs, and conducted fill-and-dump tests on a commercially available epoxy coating and a polyethylene terephthalate (PET) liner system. Our data (and that of others) indicate that properly applied epoxy coatings and properly installed PET liners effectively control release of Pb and Cu from LSLs and CSLs, respectively, into drinking water. Cu increased slightly in water exposed to epoxy coatings, perhaps due to small amounts of Cu in the epoxy (8 mg/kg); but the increases (0.4–22 μg/L) were far below those observed in uncoated controls (270–910 μg/L) and the action level for Cu (1,300 μg/L). Epoxy-coated pipe specimens exerted significant demand for free and combined chlorine, when fresh and after being stored wet or dry for more than 6 months, as did the uncoated control pipe sections.
In fill-and-dump experiments on PET-lined LSL and CSL pipe sections, we found the mean antimony (Sb) increase in extraction water samples, with a holding time of 6 hours to 4 days, to be 0.16 µg/L for LSLs and 0.20 µg/L for CSLs, far below the maximum contaminant level of 6 µg/L and well below levels found in samples from the unlined LSL control specimen (0.42–3.94 μg/L). There was no significant increase in total organic carbon (TOC). None of 10 phthalate esters determined using gas chromatography/mass spectrometry and none of phthalic acids determined using liquid chromatography mass spectrometry were detected; nor were these compounds detected in solvent extracts of a PET liner. PET liners exhibited very little chlorine demand in the first set of fill-and-dump tests and no measurable demand in later tests.
Freshly applied epoxy coatings leached an average of 0.50 mg/L TOC into the extraction waters, as well as low concentrations of BADGE (bisphenol A diglycidyl ether), BPA-like compounds (possibly artifacts of BADGE hydrolysis products), and trace amounts of BPA. The presence of BADGE is significant because epoxy coatings are widely used in water distribution systems and there are concerns regarding the potential effects of bisphenol compounds on the human endocrine system. For this reason, additional experiments were conducted to examine hydrolysis and chlorination of BADGE, BFDGE (bisphenol F diglycidyl ether, another common epoxy ingredient), and bisphenols, and to characterize and identify the observed BPA-like compounds.
BADGE hydrolysis was studied as a function of pH (2–12) at 15–40°C. BADGE hydrolyzed to BADGEH2O and then to BADGE-2H2O, the major end product under these conditions. Experimentally measured BADGE hydrolysis rates agreed well with modeled rates, thus the model can be used to estimate BADGE concentrations in water over time, facilitating exposure assessments. The half-lives of BADGE at pH 7 and 15, 25, 35, and 40°C were 11, 4.6, 2.0, and 1.4 days, respectively. The half-life of BFDGE was 5 days at pH 7 and 25°C. No hydrolysis or decay of BPA was observed over 30 days.
BADGE was unreactive with free or combined chlorine at pH values of 7.6–9.0 at 25°C, but the bisphenols reacted relatively rapidly with free chlorine. BPA half-lives with a free chlorine residual of 1 mg/L as Cl2 ranged from 3–35 minutes at pH 6–11 and 10–25°C; half-lives of 1–10 days were estimated for monochloramine (3.5 mg/L as Cl2) under similar conditions. These results and a model based on them can be used to characterize the concentrations of bisphenols and BADGE in drinking water distribution systems, after leaching from epoxy coatings, thereby facilitating future risk assessments.
The chlorine demand we observed in epoxy-coated LSLs has significant implications for disinfection byproduct formation, biofilm growth, the types and fate of chemicals that leach from epoxy coatings, monitoring of chlorine residuals in tap water, and the long-term performance of epoxy coatings. In experiments with triethylenetetramine (TETA, a common “hardening” component of amine-based epoxies) we found that it reacts rapidly in aqueous solution, with both free and combined chlorine, with most or all of the chlorine being consumed within 24 hours when chlorine and TETA are combined in a 1:1 molar ratio. Free chlorine reacts much more rapidly than combined chlorine, and appears to form organic chloramines able to be detected as total chlorine. These results are similar to those we observed in chlorine demand tests conducted on epoxy-coated LSL and CSL specimens.
A major objective of this project is to provide water utilities, engineering consultants, state regulators, consumers, and others with information helpful in making informed decisions regarding lining and coating of LSLs and CSLs. Recommendations will be developed for utilities, engineering consultants, state regulators, and consumers considering the use of these technologies to protect human health, to reduce the cost of repairing or replacing service lines, and to improve the aesthetic qualities of drinking water. Ultimately, this research will provide the drinking water community with practical information to assist efforts to ensure reliable supplies of safe drinking water for consumers.
During the next reporting period, our primary objective is to complete the draft final report, revise it based on comments received from the Project Advisory Committee, and submit the final project report for publication by the Foundation by the end of 2016. As we write the report, we also plan to: (1) continue to review pertinent literature and integrate it into the report; (2) continue to gather key pieces of information from utilities, state and provincial regulators, vendors, and others, as needed to complete the report, placing special emphasis on countries (such as the UK, The Netherlands, and Japan) where lining and coating technologies are more widely used; (3) complete our assessment of the potential for metal ions, by various mechanisms, to diffuse through or around epoxy and PET materials over time, as they age; and (4) evaluate all of the information obtained during the course of the project and finalize our recommendations for utilities, consultants, state and provincial regulators, consumers, and manufacturers interested in lining and coating technologies for lead and copper service lines.