ASSESSMENT AND CALCULATION OF BTEX …

1 ASSESSMENT AND CALCULATION OF btex permeation through HDPE water pipe FINAL REPORT JULY 10, 2012 Prepared for: HDPE Municipal Advisory Board Plastics pipe Institute (PPI) Prepared by: Dae Hyun (Dan) Koo, , I TABLE OF CONTENTS INTRODUCTION ---------------------------------------- -----------------------------------P. 1 btex DEFINITIONS AND PROPERTIES ---------------------------------------- ---- P. 3 REGULATIONS AND HEALTH EFFECTS ---------------------------------------- ----P. 6 btex TRANSPORT MECHANISMS ---------------------------------------- ------------------P.

2 9 Volatilization ---------------------------------------- --------------------------------------- P. 9 Dissolution ---------------------------------------- ---------------------------------------- -- P. 10 Sorption ---------------------------------------- ---------------------------------------- ----- P. 11 Biodegradation ---------------------------------------- ------------------------------------- P. 12 Summary ---------------------------------------- ---------------------------------------- ---- P. 12 btex permeation CALCULATION METHODOLOGY ------------------------------ P. 13 Steady State permeation Coefficient Equation ---------------------------------------- P.

3 13 Condition Variables Saturated and Unsaturated Ground water -------------------P. 16 Condition Variables Stagnation Effect in Contaminated Ground ---------------- P. 18 Condition Variables Internal water Flow Effect in Contaminated Ground ----- P. 20 Condition Variables PE pipe Thickness Effect in Contaminated Ground ------- P. 21 Condition Variables Different Ground Temperatures ------------------------------ P. 24 Condition Variables Ground Soil Type ---------------------------------------- ------ P. 28 btex permeation CALCULATION ---------------------------------------- -------------- P.

4 30 FUTURE RESEARCH-------------------------------- ---------------------------------------- ---- P. 35 CONCLUSIONS ---------------------------------------- ---------------------------------------- --- P. 36 REFERENCES ---------------------------------------- ---------------------------------------- ----- P. 38 II LIST OF TABLES Table 1. Bulk Concentration of contaminant in the Soil Pore water (C bulk) ---------------------P. 5 Table 2. Chemical and Physical Properties of btex Compounds -------------------------------- P. 6 Table 3. National Primary Drinking water Regulations for Organic Chemical ( btex ) ------- P.

5 8 Table 4. Comparison of Drinking water Standards ---------------------------------------- ---------- P. 8 Table 5. Taste and Odor Thresholds for Pure Compounds Compared to MCLs --------------- P. 9 Table 6. permeation Rates in Saturated and Unsaturated Ground Conditions ------------------ P. 18 Table 7. pipe Wall Thickness Correction Factor ( ) ---------------------------------------- ------ P. 23 Table 8. Diffusion Coefficient per Temperature Change in water ------------------------------- P. 26 Table 9. Input Parameters for btex permeation Calculations ---------------------------------- P. 31 Table 10.

6 btex permeation Results Scenario 1 Groundwater Saturated and pipe - water Flows ---------------------------------------- ---------------------------------------- -------------------- P. 33 Table 11. btex permeation Results Scenario 2 Groundwater Saturated and pipe - water Stagnates ---------------------------------------- ---------------------------------------- ----------------- P. 33 Table 12. btex permeation Results Scenario 3 Groundwater Unsaturated and pipe - water Flows ---------------------------------------- ---------------------------------------- ---------------------- P.

7 34 Table 13. btex permeation Results Scenario 4 Groundwater Unsaturated and pipe - water Stagnates ---------------------------------------- ---------------------------------------- ----------------- P. 35 LIST OF FIGURES Figure 1. btex Components in Gasoline ---------------------------------------- --------------------- P. 4 Figure 2. Flow Diagram for btex Contamination CALCULATION Process ------------------------ Figure 3. Regression Model for permeation Correction Factor by Thickness of PE pipe -----P. 24 Figure 4. Linear Regression for Benzene Diffusion Coefficient vs. Temperature ------------- P.

8 27 Figure 5. Linear Regression for Toluene Diffusion Coefficient vs. Temperature -------------- P. 27 Figure 6. Linear Regression for Ethylbenzene Diffusion Coefficient vs. Temperature ------- P. 28 Figure 7. Linear Regression for Xylene (total) Diffusion Coefficient vs. Temperature ------- P. 28 INTRODUCTION The water industry in Europe has extensively used HDPE (High Density Polyethylene) pipe for drinking water supply and distribution systems for many decades. In the US and Canada, the adoption of HDPE water pipe continues to increase in municipal and utility applications.

9 Compared to other pipe materials such as steel, ductile iron, concrete and PVC, HDPE pipes have many advantages such as flexibility, corrosion and biological resistance, fatigue (Jana 2012) and seismic resistance (Eldinger and Davis 2012) and availability of various types of joints, such as a leak free fusible joints and mechanical joints and provides the lowest life cycle costs (CSIRO 2008). As indicated in the AWWA pipe standards (such as AWWA C110, C200, C905, C906, and etc), underground pipelines can be contaminated by various chemical organic substances during service.

10 Hydrocarbon permeation occurs by external contamination sources existing around the water pipe systems. Subsequently the contaminants diffuse through the pipe wall and joints into the water carried in the pipe . AWWA Standards include similar permeation Requirements for pipes and gaskets and refer the user to consult with the manufacturer regarding permeation of pipe walls, jointing materials, etc., before selecting materials for use in such areas. As such, the Plastics pipe Institute contracted with the Purdue School of Engineering at IUPUI to develop this report to assist the users with these applications.