Prediction of PVC pipes performance under permeation conditions L. Esteve Agelet 1, C. R. Hurburgh 1 Jr., F. Mao 2, and J. A. Gaunt 2 Department of Agricultural and Biosystems Engineering 1 Department of Civil, Construction and Environmental Engineering 2 Iowa State University, Ames, Iowa 2006 IDRC Conference Chambersburg, PY 4-11 August, 2006 © 2006 Iowa State University and AwwaRF Various pathways of diffuse reflectance

INTRODUCTION Permeabilization: A mass transport or flux through a material due to an activity gradient. Concern for buried waterlines where the soil is contaminated with organic compounds, due to spills or leaks INTRODUCTION Permeabilization: A mass transport or flux of solvent through a non- metallic, porous material due to an activity gradient. Concern for buried waterlines where the soil is contaminated with organic compounds, due to spills or leaks Permeation has been a proven cause of drinking water contamination in United States and 6 other countries in recent years (Holsen et al., 1991)

OBJECTIVE Develop NIR calibrations for predicting susceptibility of PVC pipes to permeation by organic solvents

MATERIALS AND METHODS  Pipe Samples - Set of 28 pipes from 5 major manufacturers - 6 diameter sizes: ½”, ¾”,1”,1+ ¼”, 1+ ½”, and 2” - Three 5” samples from each pipe were cut for the study - 6 scans/sample  Reference data - Slope K (mm/h 1/2 ) from the moving front test using pure toluene as organic solvent

MATERIALS AND METHODS (Contd.)  Instruments Foss ® NIRsystem 6500 Foss-NIRsystems, Silver Spring, MD Labspec ® Pro A Analytical Spectral Devices, Inc., Boulder, CO  Software - The Unscrambler ® v.9.5 (Camo AS, Trondheim, Norway)  Calibration method - Raw, First and Second Svitsky-Golay Derivatives - Partial Least Squares (PLS) with cross validation

RESULTS The moving front test is an adequate method to get reference data (SEL=0.001 mm) The best PLS calibration models with raw spectral data for pipe sizes from 0.5 to 1.25” gave : Foss instrument: r 2 = 0.94 and RPD = 4.27 ASD instrument: r 2 = 0.90 and RPD = 2.72

RESULTS (Contd.)  The larger pipes were cut for Foss instrument, scanned and added in the calibration later, developing a second model.  The best PLS calibration models with raw spectral data for pipe sizes from 0.5 to 2” gave : Foss instrument: r 2 = 0.92 and RPD = 2.93 ASD instrument: r 2 = 0.90 and RPD = 1.90

CONCLUSIONS PVC pipe permeation performance can be predicted using spectral data from the NIR region. Larger pipes models did not give as accurate results as models including pipes of sizes from 0.5 to 1.25”. Models from Foss 6500 instrument were more accurate. Treatment of spectral data with derivatives gave poorer results.

ACKNOWLEDGEMENTS Iowa State University gratefully acknowledges that the Awwa Research Foundation is the joint owner of the technical information upon which this manuscript is based. Iowa State University thanks the Foundation for its financial, technical, and administrative assistance in funding and managing the project through which this information was discovered. The comments and views detailed herein may not necessarily reflect the views of the Awwa Research Foundation, its officers, directors, affiliates, or agents. The findings described here are preliminary in nature and are subject to revision. A final project report will be published by AwwaRF. © 2006 Iowa State University and AwwaRF

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