Legacy of Manganese Accumulation in Water Systems

PDF Report #4314

Subject Area: Infrastructure

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Prepared by: Philip Brandhuber and Sarah Craig HDR Engineering and

Melinda Friedman, Andrew Hill, Stephen Booth, and Amie Hanson Confluence Engineering Group, LLC

Jointly sponsored by: Water Research Foundation 6666 West Quincy Avenue, Denver, CO 80235 and

U.S. Environmental Protection Agency Washington, D.C.

Published by: Water Research Foundation

This study was funded by the Water Research Foundation (WRF) and the U.S. Environmental Protection Agency (EPA) under Cooperative Agreement #EPA-EM-83406801-1. WRF and EPA assume no responsibility for the content of the research study reported in this publication or for the opinions or statements of fact expressed in the report. The mention of trade names for commercial products does not represent or imply the approval or endorsement of WRF or EPA. This report is presented solely for informational purposes.

ISBN 978-1-60573-221-3

Printed in the U.S.A.

LIST OF TABLES ...... ix

LIST OF FIGURES ...... xi

FOREWORD ...... xiii

ACKNOWLEDGMENTS ...... xv

EXECUTIVE SUMMARY ...... xvii

CHAPTER 1: INTRODUCTION ...... 1 Legacy Manganese Defined ...... 1 Regulatory and Pubic Health ...... 2 Aesthetic and Customer Acceptance ...... 2 Utility Equipment and Customer Devices ...... 3 Labor, Energy and Other Resources ...... 3 Report Organization ...... 3

CHAPTER 2: LITERATURE REVIEW ...... 5 Objective ...... 5 Background ...... 5 General Manganese Chemistry ...... 6 Accumulation Mechanisms ...... 7 Release Mechanisms ...... 8 Health Impacts and Regulatory Requirements ...... 9 Health Impacts ...... 9 Regulatory Requirements ...... 12 Manganese Occurrence ...... 14 Presence of Manganese in Source Water ...... 14 Frequency of Manganese Treatment ...... 14 Occurrence Within the Distribution System ...... 16 Direct and Indirect Impacts of Legacy Manganese Presence in the Distribution System ...... 26 Direct Impacts ...... 27 Indirect Impacts ...... 31 Control of Manganese Prior to Entering the Distribution System ...... 33 Control of Manganese After Entering the Distribution System...... 36 Conclusions ...... 38

CHAPTER 3: UTILITY SURVEY ...... 41 Description of Survey ...... 41 Overview of Survey Results ...... 41 Summary of Participating Utilities ...... 45 Arvada, CO ...... 45

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Boulder, CO ...... 45 Lacey, WA ...... 46 Moscow, ID...... 47 Newport, OR ...... 48 Newport News, VA ...... 48 Park City, UT ...... 49 Philadelphia, PA ...... 50 Renton, WA ...... 50 United Water, ID ...... 51 Observations Regarding Survey Results ...... 51

CHAPTER 4: DETAILED CASE STUDIES ...... 55 Objective of Case Studies ...... 55 Case Study Approach ...... 56 Format for Presentation of The Case Study Findings ...... 58 Park City Case Study ...... 58 Introduction ...... 58 Topic Area 1 – Customer Satisfaction ...... 59 Topic Area 2 – Co-Occurring Contaminants ...... 61 Topic Area 3 – Response to Manganese Accumulation/Release ...... 64 Topic Area 4 – Prevention of Manganese Accumulation/Release ...... 68 Summary of Cost Impacts for All Topic Areas ...... 70 Lacey Case Study ...... 73 Introduction ...... 73 Topic Area 1 – Customer Satisfaction ...... 73 Topic Area 2 – Co-Occurring Contaminants ...... 75 Topic Area 3 – Response to Manganese Accumulation/Release Issues ...... 78 Topic Area 4 – Prevention of Manganese Accumulation/Release ...... 81 Summary of Cost Impacts for All Topic Areas ...... 84 Summary of Case Study Findings ...... 87 Comparison of Case Study Qualitative Findings ...... 87 Comparison of Case Study Quantitative Findings ...... 87 Comparison of Labor Costs for Response and Preventative Flushing ...... 95 Effectiveness of Preventative Flushing ...... 95 Inherent Impacts of Accumulated Mn ...... 95

CHAPTER 5: ESTIMATE OF MANGANESE INVENTORIES ...... 97 Terminology ...... 97 Assessment Approach ...... 97 Inventory Results ...... 98

CHAPTER 6: ASSESSING UTILITY RISK AND DETERMINING RESPONSE TO LEGACY MANGANESE ...... 103 Risk-Based Approach for Developing a Response to Legacy Manganese ...... 103 Utility Self-Assessment Framework ...... 103 Applicability of Self-Assessment Framework Process ...... 119

©2015 Water Research Foundation. ALL RIGHTS RESERVED. CHAPTER 7: CONCLUSIONS AND RESEARCH NEEDS ...... 121 Project Conclusions ...... 121 The Nature of Legacy Mn ...... 121 Problems Associated with the Presence of Legacy Mn ...... 122 Understanding the Differences Between Mn Pass-through and Mn Release Episodes ...... 122 Classification of Mn Release Episodes ...... 123 Impacts of Mn Release Episode ...... 124 Risk Factors for the Accumulation of Mn ...... 124 Risk Factors for the Release of Legacy Mn ...... 125 Use of Existing Industry Best Management Practices to Control Legacy Mn ... 125 Future Research Needs ...... 125

APPENDIX A. UTILITY SURVEY QUESTIONNAIRE ...... 127

APPENDIX B. SUMMARY OF SURVEY RESULTS ...... 145

APPENDIX C. SURVEY FOLLOW-UP TOOL ...... 155

REFERENCES ...... 163

ABBREVIATIONS ...... 167

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2.1 Summary of Mn-related regulatory requirements ...... 13

2.2 Compilation of Mn levels measured in bulk samples collected during various hydrant flushing studies ...... 18

2.3 Compilation of Mn levels in hydrant flush solids from various studies ...... 19

2.4 Compilation of Mn levels in pipe section solids from various studies ...... 22

2.5 Impacts of scaling to distribution system equipment ...... 29

2.6 Estimated hydrant flush labor efforts ...... 30

2.7 Literature recommendation for finished water Mn levels of 0.01 mg/L ...... 32

2.8 Summary of Mn treatment techniques ...... 34

2.9 Water quality conditions that impact deposit and trace contaminant stability ...... 37

3.1 Summary of the background information, water quality information related to Mn, and distribution system information as reported by the participating utilities1 ...... 43

3.2 Summary of information available from utility survey ...... 53

4.1 Utilities selected for case study ...... 55

4.2 Summary of information requested from case study utilities ...... 57

4.3 Summary of reactive and preventative flushing impacts ...... 67

4.4 Summary of Park City legacy Mn cost impacts ...... 71

4.5 Bulk water quality conditions during PVC pipe flushing trial at 7 fps ...... 75

4.6 Results of Reservoir A biofilm analysis ...... 76

4.7 Summary of iron and Mn at the point of entry for (selected) Lacey’s source waters ...... 77

4.8 Comparison of bulk water quality during flushing velocity trials on 6-inch AC pipe ..... 80

4.9 Summary of preventative flushing impacts ...... 82

4.10 Summary of Lacey legacy Mn cost impacts ...... 85

4.12 Summary of case study quantitative findings – Topic Area 1. Customer Satisfaction ..... 90

4.13 Summary of case study quantitative findings – Topic Area 2. Co-occurring Water Quality Issues ...... 92

4.14 Summary of case study quantitative findings – Topic Area 3. Response to Mn Accumulation/release ...... 93

4.15 Summary of case study quantitative findings – Topic Area 4. Prevention of Mn Accumulation/release ...... 94

4.16 Comparison of labor cost for reactive and preventative flushing – Park City ...... 95

5.1 Statistical summary of Mn inventory parameters for all pipe specimen deposit samples collected and analyzed by Friedman et al., 2010 ...... 101

6.1 Risk assessment factors for Mn entering the distribution system ...... 106

6.2 Risk assessment factors for Mn accumulation in the distribution system ...... 108

6.3 Risk assessment factors for measures to mitigate Mn accumulation ...... 110

6.4 Risk assessment factors for Mn release in the distribution system ...... 111

6.5 Potential impacts of Mn pass-thru episode ...... 113

6.6 Potential impacts of Mn accumulating in distribution system ...... 114

6.7 Potential impacts of maintaining low risk for Mn release ...... 115

6.8 Potential impacts of being at high risk for Mn release ...... 116

6.9 Example best management practices to minimize the risk of Mn accumulation/release in distribution systems ...... 118

ES.1 Project approach...... xviii

ES.2 Legacy Mn inventory for various pipe materials ...... xxii

ES.3 Utility self-assessment framework ...... xxiii

1.1 The legacy Mn puzzle ...... 2

2.1 Pourbaix diagram for Mn species ...... 6

2.2 Conceptual representation of accumulated scales and sediments ...... 7

2.3 Groundwater and surface water treatment objectives, including Mn removal ...... 15

2.4 Cumulative occurrence profile for Mn in deposit samples ...... 22

2.5 Manganese coating on a galvanized pipe specimen ...... 28

4.1 Zone-average Mn and thallium levels in daily water sampling during the 2010 excursion episode ...... 63

4.2 Pipe sample from affected zone and its deposit elemental composition ...... 63

4.3 Black film/slime layer scraped from 0.5 to 2.5 inches of a10-inch ductile iron pipe sample obtained from Park City ...... 65

4.4 Park City field crew conducting unidirectional flushing of water system ...... 69

4.5 Visual inspection of PVC pipe before and after flushing at 6 fps (left) and 10 fps (right) ...... 79

4.6 Summary of Lacey’s 2011-2012 flushing season ...... 83

5.1 Cumulative percentile Mn inventory profiles for pipe specimen deposit samples collected and analyzed by Friedman et al., 2010 based (A) on mg Mn per ft2 pipe wall area, (B) on mg Mn per liner foot of pipe length and (C) on mg Mn per pipe volume in liters ...... 100

6.1 Utility self-assessment framework ...... 105

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Denise L. Kruger Robert C. Renner, P.E. Chair, Board of Trustees Executive Director Water Research Foundation Water Research Foundation

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The authors are grateful to the organizations and individuals who contributed to this project. In particular, we sincerely appreciate the contributions of the utilities that were willing to share data and experiences with the authors.

 City of Arvada, CO  City of Boulder, CO  City of Lacey, WA  City of Newport, OR  City of Moscow, ID  Newport News, VA  Park City, UT  Philadelphia, PA  Renton, WA  United Water, ID

The authors thank Maureen Hodgins, the Water Research Foundation research manager and the project advisory committee members Mike Schock (United States Environmental Protection Agency), Orren Schneider, PhD, PE (American Water), Lina Boulos PE (L. Boulos Consulting) and Brian Lakin, PE (McMillen Jacobs Associates) for their insights and suggestions.

PROJECT BACKGROUND

“Legacy manganese,” i.e., the manganese (Mn) that has accumulated within distribution systems, can cause a number of problems for water utilities and their customers. Historically, Mn has been perceived as a nuisance contaminant because of its tendency to degrade aesthetic water quality when concentrations exceed 0.015‒0.02 mg/L. Presently, many utilities’ perception of whether they have a “Mn problem” is based on customer complaints about color, staining, and/or taste. The perception that Mn is purely an aesthetic issue is consistent with the U.S. Environmental Protection Agency’s (EPA) 2003 determination that the “regulation of Mn in drinking water does not present a meaningful opportunity for health risk reduction.” In other words, the presence of Mn at levels typically present in drinking water is not a health concern. Yet emerging research (Bouchard et al., 2011) suggests that Mn exposure from drinking water may contribute to adverse health effects. There is also a renewed concern about the health risks associated with the mere presence of legacy Mn in distribution systems. A growing body of recent research demonstrates the ability of hydrous legacy Mn oxide solids to adsorb regulated trace inorganics like lead, barium, radium, etc., thus contributing to the accumulation (and potential release) of these toxic contaminants (Friedman et al., 2010; Schock et al., 2008) during Mn release episodes. In addition to concern over health effects, legacy Mn may also adversely impact equipment performance, maintenance requirements, and equipment life span. Lastly, when customers experience colored water episodes related to the presence of legacy Mn, there may be considerable loss of public confidence in a utility. Taken together, these impacts may cause substantial (but poorly documented) costs to utilities.

PROJECT OBJECTIVES

The objectives of this project were to:

 Document the presence of legacy Mn in distribution systems  Estimate the potential impacts of legacy Mn on utilities  Provide a framework for utilities to assess and develop a proactive and appropriately designed response to legacy Mn

PROJECT APPROACH

The project followed a two-phase approach (see Figure ES.1) for assessing the impact of legacy Mn on utilities. The first phase of the project was devoted to gathering information about the impacts of legacy Mn on utilities. This was done by reviewing existing literature, surveying participating utilities, completing case studies, and performing additional evaluation of existing data to estimate a range of legacy Mn inventories that utilities may experience.1 The second phase of the project developed a utility self-assessment framework to assist utilities in proactively understanding the risks posed to their system by legacy Mn and the consequences of

1 Legacy Mn inventory is defined as the absolute mass of Mn present in the distribution system independent of mass of co-occurring elements.

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©2015 Water Research Foundation. ALL RIGHTS RESERVED. actions they may take or not take. The self-assessment also developed best management practices (BMPs) designed to minimize the risk for the accumulation and release of legacy Mn. The project concluded with a set of observations regarding the unique nature of the legacy Mn problem. Utilities need to use a risk-based management approach when responding to legacy Mn, and the chosen approach should correspond to the likelihood of a Mn release event. A set of recommendations for additional research needs were also proposed. It is important to note that this project was intended as a “desktop” study, relying on readily available information and data.

Phase 1 Phase 2 Data Collection Utility Recommendations

Literature Review (Chapter 2) Utility Self Assessment Framework (Chapter 6) Utility Survey (Chapter 3)

Utility Case Conclusion and Studies Recommendations (Chapter 4) (Chapter 7)

Mn Inventory Estimate (Chapter 5) Figure ES.1 Project approach

RESULTS

Literature Review

The literature review concluded that the possible impacts of legacy Mn touch on many areas: chemistry, treatment, costs, consumer confidence, and (potentially) health effects. Important observations of the literature review include:

 The complexity of Mn chemistry along with inherent features of distribution systems (spatially covering a large area, variations in infrastructure age, design features, time varying hydraulics, time dependent changes in water chemistry), suggest that it is more difficult to control accumulation and release in the distribution system than to prevent entry of Mn into the distribution system. However, even the most effective treatment system will still permit trace levels of Mn to enter the distribution system.  Mn episodes seriously erode customer confidence in a utility. The erosion of consumer confidence is generally not considered by utilities in estimating the cost of accumulated Mn.

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©2015 Water Research Foundation. ALL RIGHTS RESERVED.  Available data indicate that accumulated Mn may be spatially localized in distribution systems (as opposed to being uniformly distributed throughout the distribution system). This implies that localized control of Mn in the distribution system that focuses on the Mn-impacted zone, rather than system-wide control, should be considered a cost-effective approach for dealing with legacy Mn.  Recent research (Bouchard et al., 2011) appears to show that Mn impacts to public health may need to be reconsidered. These public health impacts may be caused by direct Mn exposure or through exposure to other contaminants that are found to co- occur with Mn.

Utility Survey

A survey of ten participating utilities was performed to gather information regarding their experience with legacy Mn.

Utility Experience with Legacy Mn

Under current treatment conditions, over half of the participating utilities have experienced discolored water episodes in their distribution systems, ranging from 1 to 45 episodes per year. Approximately, one quarter of these discolored water episodes occur in the parts of the distribution system that are more vulnerable to Mn accumulation and/or release. Seven of the ten utilities in the study have a response plan for addressing these episodes. Flushing the distribution system pipelines near the discolored episode location appears to be the most accepted response plan for the utilities. Seven of the ten participating utilities have a preventive flushing program in place, seven also have a reactive flushing program, and two do not perform any flushing. Six of the ten participating utilities track hours spent dealing with customer complaints related to Mn in their distribution system. About one third of the utilities have had to pay damages or make restitution to customers because of Mn staining or other impacts caused by Mn release. Two of the ten participating utilities had entered into a public relations campaign because of Mn or discolored water episodes. Two of the ten utilities experienced equipment- fouling issues within the distribution system due to Mn accumulation. All the utilities reported that the cost-incurring impacts of the Mn accumulation or release in their distribution systems are due to flushing, sampling, and time spent responding to customer complaints. None of the participating utilities reported losing customers following a Mn episode. Approximately half of the participating utilities have abandoned a water source due to Mn. Only one utility reported regulatory compliance issues related to Mn release.

Release Versus Pass-through Mn Episodes

All the surveyed utilities were sensitive to colored water episodes, but not all the utilities were able to distinguish if Mn-related colored water episodes were caused by pass-through Mn or legacy Mn. While both types of Mn episodes manifest themselves by colored water in the distribution system, their causes are different. Pass-through episodes originate at the source or in the treatment plant, and involve a failure in treatment or the absence of treatment for Mn. Generally, pass-through episodes will end when the treatment problem is solved. By comparison, release episodes are the result of chemical or physical changes in the distribution system that

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©2015 Water Research Foundation. ALL RIGHTS RESERVED. disturb legacy Mn. Release episodes will continue until the chemical or physical changes are stopped, re-equilibration with legacy deposits is reached, or the deposit of legacy Mn is fully mobilized. When responding to Mn-related colored water episodes, utilities need to understand the fundamental difference between the two types of Mn episodes.

Utility Case Studies

Detailed case studies were developed with the assistance of two utilities: Park City, UT and Lacey, WA. Although the researchers found it more difficult to quantify the impact of legacy Mn than anticipated, a number of important observations were made through the case studies. These observations are discussed below.

Utility Response to Legacy Mn

The impacts that legacy Mn may have on a utility and the utility’s response to legacy Mn can vary widely. In the case of Park City, UT, two intense and well-publicized colored water episodes (termed event release2 by this project) caused the utility to undertake an extensive response program to reassure the public about the safety of its water and reduce the amount of legacy Mn in its system. The City of Lacey, WA has less dramatic experience with legacy Mn. In response to a brown water event in a large pressure zone, the utility investigated legacy Mn in its system, instituted unidirectional flushing (UDF) as a means to reduce Mn inventory and to help prevent future accumulation, and has since installed treatment at its impacted sources.

Inherent Impacts of Accumulated Mn

It is important to note that neither the case study utilities, nor any of the survey utilities could provide cost estimates associated with decreased distribution system performance that was inherently caused by the actual presence of accumulated Mn in distribution systems. Although two utilities expressed concern about equipment fouling by Mn, none of the utilities regularly replaced equipment (valves, sensors, etc.) due to the accumulation of Mn. As discussed in the literature review, the accumulation of Mn in distribution system piping can increase pipe friction, and thereby increase pumping costs. But increased costs due to legacy Mn could not be demonstrated by any available data. Nonetheless, the presence of accumulated Mn is of great concern to utilities. This is not specifically because of its presence in the distribution but because of its potential for mobilization, along with the release of co-occurring metals. This concern has caused Park City, for example, to undertake an extensive distribution sampling program to anticipate the release of Mn and co-occurring metals prior to a visible colored water episode. The utility is also conducting extensive evaluation of various main cleaning strategies as part of WRF project #4509, “Metals Accumulation and Release Within the Distribution System: Evaluation of Mechanisms and Mitigation” (Friedman et al., forthcoming). Overall, a seemingly simple but important conclusion is that the major risk associated with legacy Mn may not be its actual presence in distribution systems, but its potential for release. As long as legacy Mn remains stable in the distribution system and does not release or

2 Event release is a term proposed by this project to describe a large-scale and intense legacy Mn-related colored water episode that generates widespread customer concern. This is contrasted with incidental release, which is smaller in scale and hard to distinguish from other types of color water episodes.

Effectiveness of Preventative Flushing

The case studies show that preventative flushing will not completely prevent Mn release or alleviate the need for reactive flushing. In fact, Park City experienced its second major colored water event after a UDF program was established in the legacy Mn-impacted areas of its distribution system (although the flushing velocity was limited to 3 feet per second (fps) at that time). Studies performed by both Park City and Lacey indicated that flushing was effective in removing accumulated particles containing Mn from pipes, but does not remove hydraulically- resistant films adhering to pipe walls. Hence, more aggressive measures are required to remove adherent Mn films or scales on pipe walls. Nonetheless, all of the case study utilities perform preventive flushing, and believe that regular preventive distribution system flushing is an important tool in reducing the inventory of legacy Mn and improving overall distribution system water quality.

Legacy Mn Inventory Estimate

Being a desktop study, it was not an objective of this project to provide a comprehensive estimate of Mn inventories (mass of Mn) accumulated in distribution systems. However, some general guidance regarding the inventory a utility may carry in its distribution system may benefit the industry. An order-of-magnitude estimate of how much Mn could accumulate in distribution system piping was calculated, drawing from the results of 46 pipe specimen deposit samples analyzed by WRF project #3118, Assessment of Inorganics Accumulation in Drinking Water System Scales and Sediments (Friedman et al., 2010). Figure ES.2 summarizes the distribution of Mn in pipe scales per square foot of pipe area for various pipe materials. Pipe material influences the amount of accumulated Mn, with unlined cast iron pipe samples containing a greater Mn inventory than ductile and galvanized pipe samples. When considering all pipe samples analyzed by WRF project #3118, the mass of Mn deposited in pipe deposits per square foot of pipe area varied from less than 0.1 mg/ft2 to over 10,000 mg/ft2, with a median mass per square foot of 210 mg/ft2. For a 6-inch diameter pipe, this equates to 3.8 lbs of Mn accumulated per mile of pipe. Since distribution systems can contain hundreds of miles of pipe, the total inventory of legacy Mn in distribution systems may run into tons.

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80%

60%

40%

Sa mple Percentile 20%

0% 0.1 1 10 100 1000 10000 100000 Manganese Accumulation (mg/sft)

All Pipe Specimens Unlined Ca st Iron Ductile a nd Ga lva nized Cement-Lined and Plastic

Source: Data from Friedman et al. 2010

Figure ES.2 Legacy Mn inventory for various pipe materials

Utility Self-Assessment Framework for Responding to Legacy Mn

A proactive self-assessment framework to evaluate the risks of legacy Mn accumulation and possible steps to mitigate the risk or impacts of release was developed for utilities (Figure ES.3). The framework is built around a utility’s systematic evaluation of four basic questions regarding legacy Mn. These questions are:

 Is Mn entering the distribution system, or has it in the past?  Is Mn accumulating in the distribution system, or has it in the past?  Are adequate measures to mitigate Mn accumulation in place?  Is there evidence of Mn releasing from the distribution system?

In order to assist utilities in determining their possible risk level for each of the above questions, tables with characteristics or evidence associated each question were developed. A simple scale of low, medium, and high risk was established to allow utilities to quickly perform a legacy Mn self-assessment. This assessment can help utilities identify their level of risk associated with legacy Mn in their system and assist in determining how resources can be best allocated to respond to their risk. A set of best management practices (BMPs) were also developed to be consider when performing this assessment. The proposed BMPs are presented in Table 6.9 of this report.

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Figure ES.3 Utility self-assessment framework

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Utilities should understand the risks posed to their system by legacy Mn and formulate their response based on an assessment of their risk. The accumulation of legacy Mn does not appear to have detrimental effects on distribution system operation beyond those associated with the presence of pipe scale or sediment. Hence, the impacts and cost of legacy Mn are not significant until a release episode occurs. Like any pipe scale or sediment, legacy Mn can be mobilized by physical or hydraulic disturbances in the distribution system. But because of Mn’s inherently complex chemistry, concerns extend beyond physical or hydraulic disturbances. Legacy Mn is also very sensitive to changes in water quality conditions, like pH and oxidation reduction potential (ORP), which can destabilize legacy Mn and cause colored water episodes. The mobilization of Mn may coincide with the release of regulated metals as well. Utilities need to guard against the occurrence of colored water episodes caused by the release of legacy Mn and be aware of the potential for the release of regulated metals during these episodes. Utilities should also understand that there may be little visual indication of a release event if it is caused by changes in chemistry, and metals are released in the soluble form. Best management practices that can minimize Mn accumulation and reduce the potential for release episodes should be undertaken by a utility whether it has a legacy Mn problem or not. Therefore, as long as a utility has good treatment and distribution system operation and maintenance practices in place, the likelihood of significant Mn release episodes should be minimized. As discussed in this report and in other industry guidance documents, there are a variety of BMPs utilities can implement on a system-specific basis pertaining to main cleaning, source water and treatment optimization, distribution system monitoring, and hydraulic and pressure management. A utility’s goal should be to achieve the following:

 Minimize Mn inventory in the distribution system  Minimize sources of Mn entering the distribution system  Minimize changes to distribution system water chemistry, particularly with respect to pH and ORP  Minimize physical and hydraulic disruptions to the distribution system

RESEARCH PARTNER:

U.S. Environmental Protection Agency

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LEGACY MANGANESE DEFINED

“Legacy manganese,” i.e., the manganese (Mn) which has accumulated within distribution systems, can cause a number of problems for water utilities and their customers. Historically, Mn has been perceived as a nuisance contaminant because of its tendency to degrade aesthetic water quality when concentrations exceed 0.015-0.02 mg/L. Presently, many utilities’ perception of if they have a “Mn problem” is based on customer complaints about color, staining, and/or taste. The perception that Mn is purely an aesthetic issue is consistent with the Environment Protection Agency’s (EPA) 2003 determination that the, “regulation of Mn in drinking water does not present a meaningful opportunity for health risk reduction.” In other words, the presence of Mn at levels typically present in drinking water is not a health concern. Yet emerging research (Bouchard at al., 2011) suggests that Mn exposure from drinking water may contribute to adverse health effects. There is also a renewed concern about the health risks associated with the mere presence of legacy Mn in distribution systems. A growing body of recent research demonstrates the ability of hydrous legacy Mn oxide solids to adsorb regulated trace inorganics like lead, barium, radium, etc., thus contributing to the accumulation (and potential release) of these toxic contaminants (Friedman at al., 2010; Schock at al., 2008) during Mn release episodes. In addition to concern over health effects, legacy Mn may also adversely impact equipment performance, maintenance requirements and equipment life span. Lastly, when customers experience colored water episodes related to the presence of legacy Mn, there may be considerable loss of public confidence in a utility. Taken together, all of these impacts may cause substantial but poorly documented costs to utilities. Thus, legacy Mn has far-reaching impacts on the overall quality of water delivered to customers, as well as on the costs and options available to utilities for operating and managing water distribution systems. As indicated by Figure 1.1 many of these issues are inter-related, and there remain significant knowledge gaps associated with each puzzle piece.

Figure 1.1 The legacy Mn puzzle

Regulatory and Pubic Health

The accumulation and possible release of legacy Mn may have regulatory or public health impacts. Mn is regulated as a secondary contaminant, indicating its presence in water is an aesthetic nuisance rather than a public health risk. Yet it is possible that the presence of legacy Mn may have an adverse impact on public health. Trace inorganics, such as arsenic (Ourvrard et al. 2002) or lead (Dong et al. 2003), may adsorb or co-precipitate with Mn accumulated in pipe scales, posing a risk to the consumer should they be released during a colored water episode releasing legacy Mn. As a component of pipe scales, legacy Mn will indirectly contribute to the formation of biofilm, which adhere to pipe scales and serve as a refuge for bacterial growth. Legacy Mn may also be responsible for increased disinfectant demand, caused directly by the oxidation of Mn species present in the bulk water or pipe scales, or indirectly by biofilm whose incidence is facilitated by the presence of Mn bearing scale.

Aesthetic and Customer Acceptance

The physical appearance of potable water can influence customer perception of its safety. Generally, customers depend on their physical senses to evaluate the safety of their water. A survey by the Scottish Environmental Quality Directorate (2007) found that customers will believe that their water is safe to drink, yet still will not do so because of their sensory perception of taste, color or odor in the water. Colored water episodes caused to the release of legacy Mn have the potential to undermine the consumer’s confidence in the safety of their water. Mn related colored water episodes might result in the staining of cloths, sidewalks, buildings and discoloration of water in pools and decorative water features. These episodes degrade customer confidence and may result in claims against the utilities for restitution of damage caused Mn containing water. Large-scale Mn-related colored water episodes can have community wide impacts, including disruption of service.

The presence of legacy Mn may cause or add to the wear and maintenance of utility infrastructure leading to the premature failure and replacement of equipment. For example, Mn scaling or fouling of instrumentation may hamper supervisory control and data acquisition (SCADA) equipment performance. Customer devices such as fixtures or point of entry/point of use (POU/POE) devices may be impacted by the accumulation of Mn as well.

Labor, Energy and Other Resources

The labor and other resources expended by a utility in response to colored water episodes resulting from the release legacy Mn can be substantial. The magnitude of a utility’s response to Mn episode is a function of several factors, including the intensity, scope, and frequency of Mn episodes as well as the sensitivity of the consumers to presence of colored water. The resources invested in dealing with legacy Mn can range from minimal: a crew occasionally sent to respond to a consumer complaint, to significant: addition of Mn treatment with a large degree of customer relations and outreach. The most frequent utility response to the release of legacy Mn involves pipeline flushing. Flushing can be performed either proactively or reactively. The objective of proactive flushing being to flush Mn bearing sediments and loosely held scales, while reactive flushing is primarily aimed at replacing poor water quality with good water quality. Legacy Mn may also contribute to additional pipeline headloss resulting in higher pumping costs and reduced energy efficiency. Legacy Mn can be incorporated into sediments, scales and in iron pipes, tubercles. Extensive tuberculation of large amounts of scaling can clog the pipes, decreasing their effective cross sectional area and greatly reducing flow. Even minor scaling or the accumulation of sediments, which do not appreciably reduce the effective cross sectional area of pipes, will increase pipe wall roughness and cause frictional losses. This is reflected is lower Hazen-Williams C factors used for aged pipe (Flowserve, 2002).

REPORT ORGANIZATION

This report is organized into seven chapters. After this introduction, Chapter 2 provides a literature review related to legacy Mn. Chapter 3 describes the utility survey and its results. This is follow in Chapter 4 by two case studies selected from the surveyed utilities. Chapter 5 presents an estimate of Mn inventories based on new analysis of data collected by the WRF 3118 project. In Chapter 6, a framework is presented for utilities to follow in assessing their risks for and accumulation of legacy Mn and providing guidance on the impacts and costs of its presence. The impacts and costs are drawn from the data collected by the utility survey and case studies. The report ends with Chapter 7, presenting conclusions and recommendations for utilities.

OBJECTIVE

Manganese that has accumulated in the distribution system as part of sediment or pipe scale is referred to as “legacy Mn”. The objective of this literature review is to present a summary of current conditions within drinking water systems and industry understanding specific to legacy Mn. It should be noted that Kohl and Medlar (2006) conducted a comprehensive literature review of Mn occurrence, health effects, regulatory background, and treatment. The reader is referred to Kohl and Medlar (2006) for a more detailed literature review on numerous aspects of Mn in drinking water. The following aspects of legacy Mn in drinking water distribution systems are discussed in this document, to varying extents based on the availability of published data:

 Background.  Health effects and regulatory requirements.  Occurrence of legacy Mn.  Direct and indirect impacts.  Remediation and preventive strategies.

BACKGROUND

It is anticipated that most distribution systems contain some level of legacy Mn, even systems that are served by surface waters with very low background Mn concentrations. For example, a drinking water utility in Washington State measured Mn levels in water flushed out of distribution system piping as part of a pilot flushing program. While the Mn level of the surface water supply entering the distribution system was 1.4 µg/L, water from one of the flushed areas exhibited 54.3 µg/L of Mn, an increase of more than 38 times the level seen entering the distribution system. This was attributed to stagnant conditions in a new, undeveloped subdivision. Kohl and Medlar (2006) studied Mn in drinking water sources, treatment and distribution system bulk water, including occurrence and treatment. The results of distribution system bulk water monitoring showed that Mn concentrations decreased as the water moved farther from the treatment plant, demonstrating that Mn was accumulating in the distribution system. The authors observed that moderate levels of Mn in finished water might cause aesthetic problems at the customer’s tap if Mn is present in the finished water over extended periods. In utility surveys, Kohl and Medlar (2006) found that the average level of Mn leaving the treatment plant was 22 µg/L with a 90th percentile of 50 µg/L. Even a moderate level of Mn entering the distribution system can potentially deposit large quantities of legacy Mn. For example, a 2 million gallon per day flow containing 20 µg/L of Mn has the potential to deposit up to 122 lb/year of legacy Mn in the distribution system. This legacy Mn can then be mobilized or released back into the water over short time periods at concentrations much greater than those found in the source of supply or finished water.

Manganese is a naturally occurring element present in soil, and water. It is essential for the health of plants and animals. Manganese chemistry is very complex and consists of multiple oxidative states. The most important states from a drinking water perspective are Mn(II), Mn(IV), and Mn(VII). Both Mn(II) and Mn(VII) are soluble in water, while Mn(IV) is not. In fact, one method for treating Mn in drinking water is to convert soluble Mn (Mn(II)) by oxidation to insoluble Mn (Mn(IV)) and remove the insoluble Mn(IV) by filtration. However, Mn treatment does not completely remove all Mn from the treated water, allowing some Mn to enter the distribution system. Kohl and Medlar (2006) point out that under moderate oxidation conditions, typically, solid MnO2 can form colloids that do not settle and are not easily captured onto a filter. But when using ozone as an oxidant, Mn oxidized to soluble Mn(VII) can reach the distribution system if too much oxidant is added. Soluble Mn(II) can be formed and reach the distribution system as well if MnO2 is chemically reduced during treatment (Kohl and Medlar, 2006). As presented by Lytle and Schock (2007) and shown in the Mn Pourbaix diagram provided as Figure 2.1, relatively small changes in treated water chemistry—specifically pH and oxidation-reduction potential (ORP)—can shift the stable form of Mn(IV) (pyrolusite) to soluble Mn(II) species. These changes in water chemistry, which are discussed in the section on release mechanisms, can occur in distribution systems. For example, systems that rely on multiple sources and/or blend surface water and groundwater are likely to experience significant changes in chemistry throughout the distribution system. Alternatively, regulatory actions may result in higher Mn disposition in distribution systems. For example, under the Groundwater Rule the increased use of disinfectants by small systems may cause additional accumulation of Mn in their distribution systems.

Source: Adapted from Lytle and Schock 2007.

Figure 2.1 Pourbaix diagram for Mn species

Sly et al. (1990) investigated Mn deposition at four points within an Australian drinking water distribution system with dirty water problems. The research was conducted using Robbins biofilm sampling devices fitted onto mains. (A Robbins device is used to collect in situ samples of biofilm growth and is fitted with multiple sample stubs, which are removed for sample analysis.) Using this device the researchers found Mn accumulation was occurring through both chemical and biological means. They determined that chemical accumulation of Mn was caused by the oxidation of aqueous Mn in the distribution system bulk water by chlorine used to provide disinfection. They also determined that biological Mn accumulation occurred when insufficient disinfectant residual was present in the distribution system to control the growth of Mn depositing biofilm. The investigators recommended that finished water Mn be controlled to below 20 g/L and chlorine residual in the distribution system be maintained at greater than 0.2 mg/L to prevent discolored water episodes related to chemical or biological accumulation. Friedman et al. (2003) described several system-specific factors that influence sediment accumulation in the distribution system. Those factors that could generally be controlled by the utility include: pipe diameter, pipe material, finished water quality, time since last cleaning, and method of last cleaning. However, accumulation is also impacted by factors that are more difficult to control by utilities, such as routine and peak demands, occurrence of hydraulic disturbances such as flow reversals, and rapidly changing flow velocities that may suspend and transport particles. As described in Friedman et al. (2010) and others (Schock and Holm 2003, Schock 2005), inorganic contaminants can physically accumulate on the surface of or be occluded within solid materials commonly found within drinking water distribution systems. These solid materials are referred to as substrates or “sinks,” and they include corrosion scales, precipitates, biofilm, and sediment. Figure 2.2 shows a conceptual representation of the heterogeneous nature of distribution system scales and sediments.

Figure 2.2 Conceptual representation of accumulated scales and sediments

Accumulation rates will be dependent on water quality conditions, mineralogy, composition properties of the contaminant substrates or sinks and hydraulic conditions. These

Physico-Chemical Accumulation

Manganese may be deposited within the distribution system through the mechanisms of precipitation and sorption (Friedman et al. 2010). Manganese precipitates may form depending on pH, oxidation-reduction potential, and other water quality conditions. These precipitates can deposit onto interior surfaces of the distribution system piping, reservoirs, and plumbing systems. Precipitates are of particular interest to research on physical contaminant accumulation. Common precipitates, such as those involving iron, Mn, aluminum, and phosphate, have been shown to have a high affinity for concentrating regulated inorganic and radiological elements (Schock, 2005). Sorption involves the retention of Mn on (adsorption) or within (absorption) the surface of a substrate. Sorption is driven by physical, electrostatic, and/or chemical interactions.

Physical Accumulation

Physical deposition occurs when particulates, such as insoluble Mn, are deposited in the distribution system by low-velocity or stagnant water. Mechanistically, this occurs when the settling velocity of the particle in the water column exceeds the scour velocity. The particle settles on the pipe wall rather than being swept along with the bulk water flow. Accumulated sediments are often associated with dead-end mains and storage reservoirs (EPA 2006b) and low velocity regions.

Biological Accumulation

Well water piping often develops dense iron and Mn encrustations of Gallionella, Leptothrix, Siderocapsa and other bacterial genera that catalyze oxidation of dissolved iron and Mn. Extracellular microbial reactions scavenge Mn in a highly efficient manner, enabling waters containing as little as 20 µg/L Mn to deposit visible MnO2 within a few days (Dickinson and Lewandowski 1996). Manganese can also be subject to sorption onto biofilm or bacterially- mediated precipitation reactions. Sly et al. (1990) studied Mn deposition onto distribution system piping and determined that microbial deposition of Mn oxidizing microorganisms coated with Mn oxides occurred in an area with no chlorine residual. Kohl and Medlar (2006) also noted the occurrence of biochemical deposition of Mn oxides onto pipe surfaces, indicating this may occur in systems without adequate chlorine residual.

Release Mechanisms

Many of the mechanisms that can contribute to Mn accumulation are reversible, allowing Mn to be released back into the water. Releases can be caused by physical, hydraulic, or chemical conditions in the distribution system.

Physical or Hydraulic Release

Physical or hydraulic disturbances may be capable of dislodging sinks (i.e. corrosion scales, chemical precipitates, biofilms and sediments) containing accumulated Mn and entraining the solids in bulk water. According to Friedman et al. (2010), examples of physical and hydraulic

©2015 Water Research Foundation. ALL RIGHTS RESERVED. disturbances which may impact distribution system sinks are: increases in flow rate and velocity (due to peak demands, firefighting activities, main breaks); flow reversals; hydraulic pressure transients (due to sudden changes in velocity, pump start/stop cycles, valve slams), valve exercising, earthwork, or construction adjacent to active system components. Lakin and Bryan (2007) reported an episode in which a 10-ton vibratory roller used for road construction physically disturbed pipe scales and sediments causing over 11,000 colored water complaints.

Chemical Release

Manganese that has accumulated on or within distribution system scales and sediments may be liberated into the bulk water by dissolution or destabilization of the sink and contaminant desorption along with other accumulated inorganic contaminants (EPA 2006b). Releases that occur in the particulate phase will have different transport properties compared to releases due to dissolution in the bulk phase. As discussed in Friedman et al. (2010), pH, oxidation-reduction potential, alkalinity, dissolved inorganic carbon (DIC), and phosphate generally govern the stability of corrosion scales. Calcium, aluminum, and sulfate are also significant to the stability of precipitates. Aluminum-based salts (e.g., aluminum sulfate hydrate; polyaluminum chlorohydrate) are often used as chemical coagulants in drinking water treatment processes. Depending on treatment efficiency and pH, aluminum may concentrate in the distribution system due to post-precipitation of coagulant residual or filter breakthrough (Snoeyink et al. 2003). Constituents such as aluminum may form films, which inhibit corrosion or barriers to diffusion (Benjamin et al. 1996; Schock 1989; Schock et al. 1995; Schock 1999; Schock et al. 1996; Snoeyink et al 2003). Changes in water chemistry can result in dissolution of these sinks, leading to releases of Mn into the bulk water or formation of new Mn-containing precipitates or scales with different compositions. Such changes in water chemistry can result from changes in treatment, source water quality, or due to blending of multiple sources with varying chemical profiles.

HEALTH IMPACTS AND REGULATORY REQUIREMENTS

Health Impacts

Manganese is a necessary element for human nutrition. Humans typically meet their dietary requirement for Mn by consuming food that contains Mn. According to the Food and Nutrition Board of the National Academy of Sciences (2001), an adequate intake level of Mn for adult men is 2.3 mg per day and for adult women is 1.8 mg per day. Manganese can be found in nuts, grains, fruits, legumes, tea, leafy vegetables, infant formula, and some meat and fish. Manganese has rarely caused toxic effects when ingested orally (EPA, 2003). However, Mn poisoning has occurred due to inhaling high levels of Mn, generally in an occupational setting. At toxic levels, Mn attacks the central nervous system and can cause, according to the EPA (2003) ataxia, dementia, anxiety, a “mask-like” face, and manganism, which is a syndrome similar to Parkinson’s disease. EPA’s Integrated Risk Information System (IRIS) includes oral, inhalation and carcinogenicity health risk assessments for Mn. The IRIS recommendations for human exposure are as follows. The Mn Reference Dose for Chronic Oral Exposure (RfD) is 1.4x10-1mg/kg-day. The Mn Reference Dose for Concentration for Chronic Inhalation Exposure (RfC) is 5x10-5

Manganese in Drinking Water

For adults, ingested Mn is regulated by homeostatic mechanisms in the body (Menezes- Filho et al. 2009), which may be the reason that toxicity due to ingestion appears to be rare. (A homeostatic mechanism can be described as self-regulating through negative feedback.) Ljung and Vahter (2007) indicate that the homeostasis may not be completely established in infants and they may have a more sensitive nervous system. Manganese retention is higher in infants than adults based on hair and blood samples, which have shown that Mn levels decrease with age (Ljung and Vahter 2007). Research has indicated that children may absorb more ingested Mn than adults (Dorner et al. 1989). Absorption of ingested Mn on a per pound body mass basis may be enhanced by a growth-related high demand for iron (Mena et al. 1969). Bouchard et al. (2011) conducted a study that included a comparison of Mn exposure from drinking water and diet, with Mn concentration in children’s hair samples. The authors point out that drinking water consumption of Mn has been of less concern because the intake from water is much less than that from eating food (except for infants). In this study, the investigators determined that Mn intake from drinking water was very small, at least two orders of magnitude less than Mn ingested from foods. However, intake of water was significantly associated with Mn content of hair and intake from food was not. Bouchard et al. (2011) conclude that their findings indicate that Mn from drinking water is metabolized differently than Mn from food. Menezes-Filho et al. (2009) reviewed existing research on the effects of Mn on children, including studies involving exposure via drinking water. The investigators determined that while Mn is recognized as a neurotoxin, research on the effects of Mn exposure on children is sparse. However, the researchers concluded that the evidence of adverse effects from Mn exposure on children is substantive enough to deserve further research. These findings agree with those of Ljung and Vahter (2007). Ljung and Vahter (2007) reviewed available literature on Mn exposure through drinking water, specifically focusing on the World Health Organization health-based guideline value for Mn. The authors point out that no single study has made a determination of a toxic level of Mn for children and infants, and that evidence does point to there being a higher risk for toxicity in children than adults. Ljung and Vahter (2007) also point out that it was unclear whether Mn exposure affects both younger children and older children or whether symptoms apparent in older children are the result of infant exposure. The authors conclude that more research is needed to understand the causal relationship between Mn exposure and children’s health. Bouchard et al. (2011) recently conducted an investigation into the relationship between Mn and children’s Intelligence Quotient (IQ) as well as the relationship between drinking water Mn exposure and Mn present in children’s hair samples (discussed above). This study included 362 children in southern Quebec between the ages of 6 and 13 years of age. The median concentration of Mn in the household drinking water was 34 µg/L (with a range of 1–2,700 µg/L). The authors found that a 10-fold increase in Mn concentration at the tap was associated in a reduction of 2.4 IQ points. These data were adjusted for other factors, including family income and maternal intelligence. The authors conclude that these findings “support the hypothesis that low-level, chronic exposure to Mn from drinking water is associated with significant intellectual impairments in children” (Bouchard et al. 2011).

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Spangler and Reid (2010) completed a study evaluating the degree of correlation between groundwater and airborne Mn concentrations and cancer age-adjusted mortality rates at the county level in North Carolina. Cancer related mortality rates per 100,000 were obtained over a 4-year period from 1997-2001 and correlated, by county, with average air Mn levels and mean groundwater Mn concentration. The mean groundwater Mn concentrations by county were estimated from the North Carolina Geological Survey groundwater database using samples taken between 1973 and 1979. The authors did not mention if the water quality data used for this study was obtained from wells used strictly for potable supply, what proportion of the population considered by the study depended on groundwater as their water source or if any treatment was in place for those individuals consuming groundwater. Ignoring these obvious shortcomings, the study concluded that groundwater Mn positively correlated with total cancer, colon cancer and lung cancer county level death rates. Spangler and Reid (2010) estimated that for each one log increase in groundwater Mn, total cancer mortality rates at the county level increased by 12.1 deaths per 100,000. Using the same methodology, the authors estimated for each one-log increase in groundwater Mn, there was a 2.84 and 7.73 times increase in colon and lung cancer deaths per 100,000 respectively.

Co-occurrence With Other Contaminants

Manganese oxides and oxyhydroxides have been shown to be important in scavenging dissolved trace metals such as lead (Dong et al. 2003) and arsenic (Ourvrard et al. 2002) from natural waters. The scavenging properties of Mn oxides are so good that it forms the basis for the use of the precipitation of Mn dioxide as an analytical method to pre-concentrate trace metals such as aluminum, cadmium, copper, nickel, lead, vanadium, zinc, and rare earth elements (Umashankar et al. 2002). Thus, legacy Mn may pose a health risk due to the possible release of co-occurring regulated inorganic contaminants (Schock and Holm 2003; Schock 2005). These regulated contaminants are typically monitored (per regulatory requirements) after drinking water has been treated but prior to distribution, and therefore utilities do not typically monitor these contaminants in the distribution system. It appears possible that during releases of legacy Mn, drinking water customers could be exposed to other contaminants at levels greater than maximum contaminant levels for those contaminants. As discussed in Friedman et al. (2010), Schock and Holm (2003), Schock (2005) and others under certain conditions, such as during disequilibrium or dissolution episodes caused by changing water chemistry, contaminant releases may not necessarily be visible to consumers. Friedman et al. (2010) described accumulation trends and contaminant behavior for two broadly divided groups—trace metal cations and anionic compounds. Trace metal cations include barium, lead, nickel, and radium isotopes. These elements have a strong affinity for hydrous manganese oxides (HMOs) and an apparent affinity for phosphate precipitates and/or phosphate surface groups. Their accumulation by adsorption/co-precipitation mechanisms is typically enhanced under conditions of elevated pH and when potentially competitive cations (e.g., calcium, magnesium) are present at low concentrations. Trace anionic compounds include the oxoacids arsenate, chromate, and vanadate, as well as complexes of uranyl. These compounds have a strong affinity for HMOs and hydrous ferric oxides. Their accumulation by adsorption/co-precipitation mechanisms is typically enhanced under conditions of low pH and when potentially competitive anions (e.g., bicarbonate, phosphate, silicate) are present at low concentrations.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Sandvig et al. (2008) describe how scales on lead piping (such as lead service lines) consist of multiple layers with the surface-most layer being somewhat lower in total lead, but high in amorphous compounds of other elements such as iron and Mn. The authors hypothesized that change in water chemistry that increase the solubility of the iron and Mn minerals could destabilize the structure of the surface-most layer, releasing lead-rich particles. Cantor (2006) discusses a case study for the Madison Water Utility in which a full lead service line replacement program was undertaken. The study concluded that the combination of lead service lines (LSL) with iron/Mn scales might put individual sites at risk for high levels of total and particulate lead. The researchers demonstrated that lead concentrations at residences prior to LSL replacement were erratic, and remained erratic for four years after replacement due to lead particulate matter dislodging from pipe walls and sporadically becoming entrained in water samples. Dissolved lead concentrations were immediately reduced with LSL replacement. Scale analysis (Schock 2006) verified that the lead compounds were intermingled with Mn and iron scale layers. Lytle et al. (2004) did not find a relationship between arsenic and Mn levels, or between arsenic and any other major constituents of the pipe and hydrant flush solids collected from 15 Midwestern utilities. The authors concluded that arsenic associated with distribution system solids varies widely, is difficult to predict, and likely depends on a combination of many factors such as water chemistry, pipe material and age, flushing procedures and frequency, and solids retention and exposure time. Welch et al. (2010) was unable to find an overall correlation between the accumulation of trace metals and the amount of Mn in scales on lead service line samples taken from 21 utilities. However, correlations were found between amounts of certain trace metals including barium, nickel, chromium and the amount of Mn in scale taken from individual utilities. The authors concluded that while Mn may not control trace metal accumulation, Mn scale destabilization can still release accumulated metals.

Regulatory Requirements

Table 2.1 provides a summary of regulatory requirements related to Mn from selected countries and regulatory agencies. Three of the six agencies have set a health-based regulatory limit for Mn, and all six have set non-enforceable aesthetic-based limits.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 2.1 Summary of Mn-related regulatory requirements Health Year Country Specific Based Aesthetic Country/Agency Cited Designation Value Objective Resource Australia/National Australian Drinking Water Resource 2004 Guideline Value 0.5 mg/L 0.1 mg/L Guidelines Management Maximum Canada/ Health Guidelines for Canadian 2010 Acceptable 0.05 mg/L Canada Drinking Water Quality Concentration European Communities(Drinking European Union 2007 0.05 mg/L Water)(NO. 2) Regulations Japan/Ministry of Revision of Drinking 2004 Standard Value 0.05 mg/L 0.01 mg/L Health Water Standards in Japan Secondary EPA United 2011 Maximum 0.05 mg/L http://water.epa.gov/drink/ States/EPA Contaminant Level contaminants/index.cfm World Health 0.05-0.1 Guidelines for Drinking 2008 Guideline Value 0.4 mg/L Organization mg/L Water Values

United States

In the United States, Mn is considered an aesthetic problem and is not regulated with the objective of protecting public health. The EPA currently does not regulate Mn as part of the National Primary Drinking Water Standards. The EPA has set a Secondary Maximum Contaminant Level (SMCL) for Mn of 0.05 mg/L. SMCLs are non-enforceable levels set by the EPA to indicate that concentrations above these levels may cause aesthetic problems (such as color or taste), cosmetic problems (such as staining), or technical effects (due to staining or corrosion). In 2004, the EPA completed an evaluation of the need to develop a primary drinking water standard for Mn. The EPA concluded that, based on available data, Mn did not present a meaningful opportunity for health risk reduction. Therefore, the EPA has set a Drinking Water Health Advisory Value (HAV) for Mn of 0.3 mg/L (EPA 2004). An exposure of this level of Mn on a daily basis is not expected to result in adverse health effects. With respect to acute exposure to Mn, the EPA has set one-day and 10-day HAVs at 1 mg/L. The EPA does indicate that for infants, the acute exposure HAV is 0.3 mg/L due to concerns regarding absorption and excretion in infants. Since these HAVs have been established, some research, described previously, has been completed that suggest concerns regarding Mn exposure for children and the co-occurrence of Mn with other drinking water contaminants. Additionally, legacy Mn presents the possibility of periodic releases of accumulated Mn (and associated trace contaminants) that could result in periods of acute or sub-chronic exposure and differing health impacts.

The World Health Organization (WHO) has established a guideline level of 0.4 mg/L for Mn. The WHO guidance notes that this is significantly higher than what is considered acceptable from an aesthetic standpoint, with customers generally finding water containing Mn concentrations below 0.05–0.1 mg/L aesthetically acceptable.

Other Countries

Canada’s guidelines for drinking water quality establishes an aesthetic objective for Mn of less than or equal to 0.05 mg/L. The European Union has established a Directive value of 0.050 mg/L for Mn. Japan has established a drinking water standard of 0.05 mg/L for Mn, and a supplemental target value of 0.01 mg/L.

MANGANESE OCCURRENCE

Presence of Manganese in Source Water

Manganese can be present in many waters including groundwater, surface water sources (such as rivers) and lakes and reservoirs. Each source type has different characteristics (such as contact time with Mn-bearing soil and rock, oxidation/reduction potential, etc.) that generally govern the amount of Mn in solution. Between 1984 and 1986, the National Inorganic and Radionuclide Survey (NIRS) collected data from 989 U.S. community public water systems (PWSs) served by ground water in 49 states. They found that 68% of the ground water PWSs reported detectable levels of Mn, with a median concentration of 10 µg/L. Supplemental survey data from PWSs supplied by surface waters in five states reported occurrence ranges similar to those of ground water PWSs. Overall, the detection frequency of Mn in U.S. ground water is high (approximately 70% of sites assayed have measurable Mn levels) due to the ubiquity of Mn in soil and rock, but the levels detected in ground water are generally below levels of public health concern (EPA 2003). Similarly, Mn is detected in about 97% of surface water sites (at levels far below those likely to cause health effects) and universally in sediments and aquatic biota tissues (at levels which suggest that it does not bioaccumulate; EPA 2003). Casale et al (2002) evaluated Mn concentrations in source waters from utilities that provided data to the 1996 American Water Works Association (AWWA) WaterStats Database. Approximately 35% of the 349 groundwater systems participating in the survey reported source water Mn concentrations exceeding 50 µg/L. Approximately 40% of the 428 surface water systems participating in the survey reported source water Mn concentrations exceeding 50 µg/L. Kohl and Medlar (2006) found that source water Mn levels were much greater in groundwater sources compared to surface water sources. However, they also concluded that Mn levels measured in bulk water samples collected from distribution systems were similar for groundwater and surface water utilities.

Frequency of Manganese Treatment

There are approximately 153,530 public drinking water systems in the United States, 51,651 of which are community water systems. Seventy-eight percent of these systems, representing 30% of the population (88,032,021 persons), are served by groundwater (EPA, 2009). According to the EPA Community Water System Survey (2006), 73.5% of survey

©2015 Water Research Foundation. ALL RIGHTS RESERVED. respondents use groundwater as their primary water source, and 13% of the groundwater systems provide treatment for Mn (removal or sequestration), while 21% of the surface water systems provide treatment for Mn. The survey also states that 23% of treatment plants provide treatment for removal or sequestration for iron. As can be seen in Figure 2.3, which presents various treatment objectives for surface water and groundwater treatment plants, Mn treatment is a frequent treatment objective. The incidence of Mn control as a treatment objective is roughly on the same order as taste and odor control. It is very difficult to extrapolate these results to determine the actual number of Mn treatment plants nationwide, since survey results can have many biases, based on the number and types of systems that responded. Kohl and Medlar (2006) report that for the 242 systems included in their utility survey, Mn levels entering the distribution system were almost always less than 50 µg/L. Seventy two percent of the surveyed utilities had less than 20 µg/L of Mn entering the distribution system. While it is encouraging that treatment systems appear to effectively remove Mn from source water, there is no way to determine the quantity of Mn that was loaded into the distribution system prior to treatment implementation, nor the quantity of Mn that continues to accumulate, albeit at very low rates, due to a wide variety of system-specific factors. Thus, analysis of current treatment practices probably yields little useful information with regard to determining existing quantities of legacy Mn. Further details on methods and efficacy of treatment of Mn can be found in the Remediation and Preventive Strategies discussion below.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Other Fluoridation Mussel Control Percentage Surface Water Security Plants Radionuclides Removal Inorganics Removal Percentage Groundwater Plants VOCs Removal Recarbonation Softening (Hardness Removal) Particulate/Turbidity Removal TOC Removal Taste/Odor Control Manganese Removal Iron Removal Oxidation Dechlorination Disinfectant By‐product Control Secondary Disinfection Primary Disinfection Corrosion Control Algae Control

0 20406080100 % of Systems Providing Treatment to Meet Objectives

Source: EPA 2006b

Figure 2.3 Groundwater and surface water treatment objectives, including Mn removal

Occurrence Within the Distribution System

Until now, the accumulation of legacy Mn in distribution systems has not been a topic of focused study. Instead the current understanding of how Mn accumulates in distribution systems has come indirectly from the work of a few utilities and researchers studying distribution system flushing efficacy, contaminant presence in the distribution system, and pipe scales. This section summarizes the quantity of distribution system Mn observed during these investigations.

Hydrant Flush Manganese Concentrations

This section includes information on Mn levels observed during hydrant flushing (both grab sample results and results of solid samples) from various researchers. Numeric results for bulk water samples collected during flushing are compiled in Table 2.2. Numeric results for solid samples collected during flushing are compiled in Table 2.3. Additional information associated with the studies compiled in Table 2.2 and Table 2.3 is provided below.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. A large utility in Alaska (EES 2001) conducted a pilot flushing program in summer 2001 and monitored, among other water quality parameters, Mn presence in the flushed water. Table 2.2 presents the average total Mn level from bulk water samples collected at the beginning and end of flushing. Typically, the total Mn concentration dropped to a concentration below the Secondary Maximum Contaminant Level (SMCL) of 0.050 mg/L within flushing five pipe volumes. Friedman et al. (2003) conducted a study focusing on the impact of flushing velocity on solids within the distribution system. As part of this research, 10 utilities participated in 19 hydrant flushes to determine if higher velocities removed more or different types of material. Grab samples were collected at the beginning, mid-point, and end of each hydrant flush. The researchers conducted analyses of the Mn concentrations of these grab samples to develop a “normalized theoretical mass,” an estimate of the mass of Mn removed over pipe surface area. These estimated masses are reported in Table 2.2. Additionally, the researchers conducted 16 hydrant flushes at 10 utilities during which particulates were captured in order to describe the nature of distribution system deposits and evaluate flushing performance. Manganese comprised 0 to 2.5% by mass of the captured particulates in these tests. Lytle et al. (2004) studied arsenic levels in 67 distribution system solid samples collected from 15 groundwater drinking utilities in Ohio, Michigan, and Indiana with sources containing iron and arsenic. As part of this study, the investigators quantified the elemental composition, including Mn, of hydrant flush samples and pipe interior solids. Table 2.3 include Lytle’s findings with respect to the presence of Mn in hydrant flush solid samples. Manganese complaints increased in Madison, Wisconsin in 2005 (Schlenker et al. 2008), especially in a neighborhood served by a single well containing Mn. A single sample collected from a customer’s tap in this neighborhood had a Mn concentration of 224,000 g/L. At this time, twenty-four groundwater wells supplied Madison with drinking water. On average, the wells had a Mn level of 28 g/L, with 21 of the wells producing water below 50 g/L (Schlenker et al. 2008). The wells with the three highest Mn levels ranged from 53 g/L to 124 g/L. Madison Water Utility collected 2,075 samples at 1,118 properties served by the utility, collecting the majority of these samples in locations served by wells with the highest levels of Mn. Of these samples, 90% were less than 50 g/L. Eleven of the samples (0.6%) collected had Mn levels greater than 300 g/L. Upon repeat testing at these 11 locations, all were less than 300 g/L. The highest Mn samples were often collected from infrequently used hose bibs or unoccupied properties. Madison Water Utility also analyzed data to determine whether locations served by the high Mn wells had higher Mn levels than those seen throughout the service area. Three of the four high Mn wells served locations with a higher number of samples in the 50 –149 g/L range (9–15%) than the rest of the service area (3.5%), demonstrating that while samples containing relatively high levels of Mn were present throughout the distribution system, more were located in areas served by high Mn wells. As discussed earlier, a medium-sized utility in Washington State conducted a pilot flushing program in 2007 and monitored Mn presence in the flushed water. Table 2.2 presents the average total Mn level of samples collected at the beginning of flushing hydrants. Investigators determined that while the surface water supply contains a very low level of Mn, relatively high levels of Mn had accumulated because this piping is located in a new undeveloped subdivision where stagnant water conditions exist, thereby creating an

©2015 Water Research Foundation. ALL RIGHTS RESERVED. environment conducive to the settling of these solids. The study does not include information on Mn levels at the end of flushing efforts. Friedman et al. (2010) investigated the elemental composition of 26 hydrant flush solids and 46 pipe scale solids collected from 20 participating utilities. The researchers noted that 11 of the 20 utilities reported Mn concentration at the distribution system entry point to be greater than 10 g/L. Results for Mn levels in hydrant flush solids are included in Table 2.3 and in Figure 2.4.

Table 2.2 Compilation of Mn levels measured in bulk samples collected during various hydrant flushing studies Dist. System Hydrant Finished Bulk Pipe Flush Bulk Utility/ Source Water Water Material Water or Data Water Pop. Mn Mn Sample in Flush Surface Source State Type Served (µg/L) (µg/L) Type Zone Loading Mn Beginni Asbestos ng of cement 1,000 Surface flush and cast µg/L1 and iron EES 2001 AK 52,000 < 20 Ground Asbestos water End of cement 20 µg/L1 flush and cast iron Old, Loop unlined 42.7 µg/L A11 cast iron HDR New WA Surface 47,000 1.4 2008 cement- Loop lined 54.3 µg/L A21 ductile iron Surface Asbestos Friedman ANC-5 6.5 mg/ft2 2 and -Cement et al. AK 52,000 < 20 Ground Asbestos 2003 ANC-13 3.4 mg/ft2 2 water -Cement Friedman ND – Unlined et al. NH DOV-3 0.6 mg/ft2 2 150 Cast Iron 2003 Unlined Friedman NNH-3 13.1 mg/ft2 2 Cast Iron et al. VA <10 Ductile 2003 NNI-4 2.9 mg/ft2 2 Iron Unlined Friedman POR-6 35.7 mg/ft2 2 Cast Iron et al. OR <10 Unlined 2003 POR-12 14.1 mg/ft2 2 Cast Iron 1 Average of total Mn values collected during hydrant flushing. 2 Manganese concentrations observed during the flush were used to estimate the mass of Mn removed normalized to pipe surface area flushed.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 2.3 Compilation of Mn levels in hydrant flush solids from various studies Distribution Source System Pipe Hydrant Utility/ Source Water (Bulk Material Flush Solid Data Water Pop. Mn Water) in Flush Mn Source State Type Served (µg/L) Mn (µg/L) Sample Zone (µg/g)/(%wt) Cast 1-1 89/0.01 Iron Asbestos Utility 1 1-2 2,295/0.23 Ground- Cement (Lytle et OH 29 water 1-3 94/0.01 al. 2004) 1-4 1061/0.11 1-5 139/0.01 Cast 2-1 10,579/1.06 Iron Cast 2-2 981/0.10 Iron Cast Utility 2 2-3 3,576/0.36 < 10 Iron (Lytle et OH al. 2004) 2-6 1,591/0.16 2-7 1,612/0.16 2-8 679/0.07 2-9 360/0.04 2-10 1,958/0.20 5-1 1,611/0.16 5-2 9,876/0.99 Utility 5 10 5-3 12,028/1.20 (Lytle et OH 14 5-4 17,881/1.79 al. 2004) 5-5 13,521/1.35 5-6 10,833/1.08 6-1 523/0.05 Utility 6 6-2 330/0.03 (Lytle et MI 19 al. 2004) 6-3 698/0.07 6-4 434/0.04 < 10 Utility 7 7 (Lytle et MI 7-2 682/0.07 5 al. 2004) 6 (continued)

Cast W-D 240/0.02 Iron Utility W Ground- Cast (Friedman 7,000 0.04 W-E 177/0.02 water Iron et al. 2010 Cast W-F 99.6/0.01 Iron Utility CL Cast CL-F: 0.4 CL-F 1,192/0.12 (Friedman Ground- Iron 28,000 et al. water Cast CL–G: 0.1 CL-G 614/0.06 2010) Iron Utility SA Ground- SA-D Cement- 1,461/0.15 (Friedman water SA-D: 1.2 lined 60,000 et al. and SA-E: 0.3 Cement- SA-E 3,509/0.35 2010) Surface lined Utility G (Friedman Ground- Cast 5,000 0.2 G-A 488/0.05 et al. water Iron 2010) (continued)

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 2.3 (Continued) Distribution Source System Pipe Hydrant Utility/ Source Water (Bulk Material Flush Solid Data Water Pop. Mn Water) in Flush Mn Source State Type Served (µg/L) Mn (µg/L) Sample Zone (µg/g)/(%wt) Cast J-A 1,235/0.12 Iron Cast J-B 30.11/0.003 Iron Cast J-C 387/0.04 Iron Cast J-D 390/0.04 Iron Utility J Cast J – A-D, G- J-E 760/0.08 (Friedman Ground- Iron 145,000 J: 55.4 et al. water Cast J-E, F: 7.8 J-F 322/0.03 2010) Iron Cast J-G 443/0.04 Iron Cast J-H 1,459/0.15 Iron Cast J-I 613/0.06 Iron Cast J-J 1,091/0.11 Iron Utility NC Ground- (Friedman 200 30.0 NC-A PVC 210/0.02 water et al. 2010) Utility ST Cement- ST-C: ST-C 2,949/0.30 (Friedman Ground- Lined 15,000 <0.01 et al. water Cast ST-D: 1.9 ST-D 845/0.09 2010) Iron Utility K Cast K-C 825/0.08 (Friedman Ground- Iron 8,000 9.0 et al. water Cast K-D 396/0.04 2010) Iron

Pipe scale

As described earlier, Lytle et al. (2004) and Friedman et al. (2010) investigated the composition of distribution main scales from numerous utilities. Results for Mn occurrence are presented in Table 2.4. Figure 2.4 summarizes Mn occurrence levels observed by Friedman et al. (2010) from pipe specimens, hydrant flushed solids, and all solid samples in the data set (n=58). The median Mn level was 790 µg/g (0.08% wt), and the average level was 7,320 µg/g or about 0.73 % weight. The standard deviation was 31,200 µg/g (3.1% weight). The Mn level for the bulk of the samples was between 300 µg/g and 2000 µg/g. In the most extreme case, a specimen

©2015 Water Research Foundation. ALL RIGHTS RESERVED. of HDPE pipe that has been exposed to water with an average Mn level 50 g/L for a period of nearly eight years had a developed a thick, friable layer comprised of 23.2 wt% Mn.

100%

80%

60%

40%

Sa mple Percentile 20%

0% 100 1,000 10,000 100,000 1,000,000 Manganese Concentration (μg/g)

All Solid Sa mples Pipe Specimens Hydrant Flush Solids

Source: Friedman et al. 2010. Reprinted with permission of the Water Research Foundation.

Figure 2.4 Cumulative occurrence profile for Mn in deposit samples

Schock et al. (2008) conducted research on the accumulation of contaminants on lead pipe scales. The authors emphasize that this study was not conducted to quantify, on a national level, contaminant accumulation in pipe scales. This research analyzed the pipe scales from 91 lead pipe specimens obtained from 26 utilities in eight states. These samples were collected over 15 years and represented both surface water and groundwater sources of supply. The average and median Mn levels were 17,451 and 4,960 mg of Mn per kg of pipe scale (approximately 1.75 and 0.50 % by weight), respectively, with a maximum measurement of 177,200 mg/kg. Manganese was categorized as a “major contaminant,” according to the presence by weight in the pipe scale.

Table 2.4 Compilation of Mn levels in pipe section solids from various studies Distribution Source System (Bulk Pipe Section Utility 1 Water Pop. Water) Pipe Solid Mn (Source) State Type Served Mn (µg/L) Sample Material (µg/g)/(% wt) Cement- Utility 2 2-4 10,187/1.02 < 10 lined iron (Lytle et al. OH Cement- 2004) 2-5 1,112/0.11 lined iron Utility 3 3-1 PVC 5,141/0.51 (Lytle et al. OH 292 2004) 3-2 PVC 1,267/0.13 Cement- Utility 4 < 10 4-1 638/0.06 (Lytle et al. IN < 10 lined iron 2004) 4-2 Cast iron 609/0.06 (continued)

Table 2.4 (Continued) Distribution Source System (Bulk Pipe Section Utility 1 Water Pop. Water) Pipe Solid Mn (Source) State Type Served Mn (µg/L) Sample Material (µg/g)/(% wt) Utility 6 (Lytle et al. MI 19 6-5 Cast iron 553/0.06 2004) < 10 Utility 7 7 (Lytle et al. MI 7-1 Cast iron 1,242/0.12 5 2004) 6 Utility 8 8-1 Cast iron 18,591/1.86 110 (Lytle et al. MI 8-2 Cast iron 20,585/2.06 6 2004) 8-3 Cast iron 6,897/0.69 Utility 9 (Lytle et al. OH < 10 9-1 Cast iron 287/0.03 2004) 10-1 Cast iron 1,804/0.18 10-2 Cast iron 1,090/0.11 10-3 Cast iron 744/0.07 10-4 Cast iron 585/0.06 10-5 Cast iron 219/0.02 10-6 Cast iron 1,838/0.18 10-7 Cast iron 469/0.05 10-8 Cast iron 1,417/0.14 Utility 10 10-9 Cast iron 318/0.03 (Lytle et al. MI 24 10-10 Cast iron 936/0.09 2004) 10-11 Cast iron 415/0.04 10-12 Cast iron 860/0.09 10-13 Cast iron 312/0.03 10-14 Cast iron 627/0.06 10-15 Cast iron 186/0.02 10-16 Cast iron 324/0.03 Not 10-17 884 2 /0.09 Available 30 3 Not 11-1 312/0.03 36 3 Available Utility 11 34 3 Not (Lytle et al. OH 11-2 660/0.07 77 3 Available 2004) 30 3 Not 11-3 2,083/0.21 38 3 Available Utility 12 5 Not (Lytle et al. MI 12-1 88/0.01 5 Available 2004) (continued)

Table 2.4 (Continued) Distribution Source System (Bulk Pipe Section Utility 1 Water Pop. Water) Pipe Solid Mn (Source) State Type Served Mn (µg/L) Sample Material (µg/g)/(% wt) Utility 13 13-1 Cement 1454/0.15 (Lytle et al. MI 13-2 PVC 290/0.03 2004) 13-3 PVC 1143/0.11 Utility 14 Asbestos (Lytle et al. MI 50 14-1 632/0.06 Cement 2004) Utility 15 (Lytle et al. OH 20 15-6 Plastic 882/0.09 2004) (Schock et al. Lead 4,9604/1.75 2008) Utility W W-A Cast Iron 447/0.05 Ground- (Friedman et 7,000 0.04 W-B Cast Iron 976/0.10 water al. 2010) W-C Cast Iron 816/0.08 CL-A Cast Iron 400/0.04 Utility CL CL-A,B: CL-B Cast Iron 362/0.04 Ground- (Friedman et 28,000 0.06 CL-C Cast Iron 372/0.04 water al. 2010) CL-C: 0.03 CL-D Cast Iron 1,393/0.14 CL-E Cast Iron 580/0.06 Ground- Utility SA water Cement- (Friedman et 60,000 0.1 SA-B 313/0.03 and Lined al. 2010) Surface Utility CH Ground- 11,000 (Friedman et 0.3 CH-A Steel 1,319/0.13 water pop al. 2010) Galvanized Utility RW RW-A 635/0.06 Ground- Iron (Friedman et 6,300 0.5 water Galvanized al. 2010) RW-B 1,628/0.16 Iron Ductile IN-B 1,342/0.13 Ground- Iron Utility IN water Ductile (Friedman et 57,000 6.6 IN-C 691/0.07 and Iron al. 2010) Surface Ductile IN-D 654/0.07 Iron (continued)

Table 2.4 (Continued) Distribution Source System (Bulk Pipe Section Utility 1 Water Pop. Water) Pipe Solid Mn (Source) State Type Served Mn (µg/L) Sample Material (µg/g)/(% wt) CC-A Cast Iron 46.69/0.01 Utility CC Ground CC-B Cast Iron 28.95/0.003 (Friedman et 1,900 3.9 -water al. 2010 CC-C Cast Iron 14.12/0.001 CC-D Cast Iron 21.65/0.002 Ground CA-A Steel 1,166/0.12 Utility CA -water (Friedman et and 100,000 0.2 al. 2010) Surface CA-B Cast Iron 139/0.01 Water Ground Galvanize Utility PC PC-A 2,597/0.26 -water d Iron (Friedman et 8,000 0.02 and Galvanize al. 2010) PC-B 2,790/0.28 Surface d Iron Utility WDB Ground WDB- (Friedman et 1,200 50.0 HDPE 232.4/0.02 -water A al. 2010) WA-A Cast Iron 3,714/0.37 Utility WA Ground WA-B Cast Iron 129/0.01 (Friedman et 6,000 11.1 -water WA-C Cast Iron 386/0.04 al. 2010) WA-D Cast Iron 2,292/0.23 Ductile Ground B-A 928/0.09 Utility B -water Iron Ductile (Friedman et and 100,000 0.1 B-B 715/0.07 al. 2010) Surface Iron Water B-D Cast Iron 402/0.04 Utility ST Ground (Friedman et 15,000 < 0.01 ST-A Cast Iron 3,925/0.39 -water al. 2010) Utility K Ground (Friedman et 8,000 9.0 K-A Cast Iron 938/0.09 -water al. 2010) 1 Listed in same manner used to designate utilities in literature. 2 This result was listed as a hydrant flush sample, but other information indicates it was a pipe section sample. 3 Note: These samples were collected in a building. 4 The median measurement from 91 samples.

As mentioned at the beginning of this section, a specific study to quantify of the amount of Mn that may accumulate in distribution systems has not been attempted. At present, estimates of the quantity of accumulated Mn can only be made indirectly from information gathered by other studies. Nonetheless, by assessing data from the flushing and pipe solids studies described above some general observations can be made:

 Manganese can be detected in solids mobilized by flushing and in solids found on pipe walls. Higher levels of Mn have been found in pipewall solids compared to those solids mobilized by flushing.  While the amount of Mn found in mobilized solids or pipe wall solids can vary widely, the amount of Mn is typically less than 1% by weight. Based on analysis performed by Friedman et al. (2010), the preponderance (60%) of pipe wall solids analyzed contained between 0.03% and 0.2% by weight Mn. Schock et al 2008 observed from 7 mg/kg to nearly 18% by weight in 91 lead pipe scales, with the average being approximately 1.8% and a median of approximately 0.5%.  The amount of Mn released by flushing can vary widely. Estimates by Friedman et al. (2010) of the mass of Mn released per unit area of pipe flushed during flushing ranged from 0.6 mg/ft2 to 35.7 mg/ft2.  While it is reasonable to assume that there is a positive correlation between bulk water Mn concentrations in the distribution system and mass loading of Mn in pipe wall solids, insufficient data exists to prove that this is true.  The loading of Mn accumulated in a distribution system (mg/ft2 pipe area) can vary widely within the distribution system. This implies that Mn accumulation may occur over broad areas of the distribution system with low loading of accumulated Mn or in localized area of high loadings of accumulated Mn. Variables such as water chemistry, pipe material, age of pipe, operational history, and hydraulic characteristics, as well as history of main cleaning techniques will impact the degree of accumulation observed.

DIRECT AND INDIRECT IMPACTS OF LEGACY MANGANESE PRESENCE IN THE DISTRIBUTION SYSTEM

Kohl and Medlar (2006) concluded that consumer reducing complaints is typically the motivation for utilities to implement or modify Mn treatment and/or apply system maintenance practices (e.g., flushing) to improve aesthetic quality. According to the authors, many utilities, particularly those with seasonal or intermittent Mn problems, do not feel they can justify the cost for major treatment improvements simply to achieve a reduction in customer complaints, i.e., they believe there needs to be a health-based driver. However, there may be the potential for public health issues under certain release scenarios as discussed above. In addition, it is worth noting that from the customer’s perspective, palatability and other aesthetic properties are often a major factor in their perception of the safety of the water. It appears that some utilities believe it is more cost-effective to increase O&M activities (e.g., distribution system flushing or pigging) rather than incur large capital costs to retrofit or add onto existing treatment plants. This is a completely rational approach as long as utilities recognize the total and life cycle costs of enhanced distribution system O&M, as well as intangible issues and costs, which although

©2015 Water Research Foundation. ALL RIGHTS RESERVED. difficult to quantify, suggest that most consumers would be willing to pay an additional price for water that consistently meets their expectations for aesthetics. In addition to aesthetic concerns and the possibility of health impacts, Mn accumulation within the distribution system can cause impacts on utility infrastructure and operational practices. For example, some utilities have adopted the approach of “don’t stir anything up” thereby limiting proactive and important valve and hydrant exercising programs, as well as implementation of flushing programs. Some of these impacts, referred to as direct impacts, have relatively straightforward expenses associated with them, they are directly related to Mn occurrence, and/or they involve purchasing equipment or require additional power. However, other impacts, referred to as indirect impacts, are difficult to monetize, such as the impacts to customer acceptance of the available water quality and trust in the water purveyor. Currently, there is very little and published data, either peer-reviewed or non-peer-reviewed, related to quantification of direct and indirect impacts associated with legacy Mn.

Direct Impacts

Utility Equipment and Customer Devices

The release of legacy Mn into distribution system water can result in costs associated with reimbursing customers for stained clothing or replacement of utility equipment such as valves or piping subject to scale and sediment. For example, a city in Washington State (serving 3,500 people), received 34 water quality-related customer complaints in August and September 2007. The causes of the dirty, cloudy, and/or rusty water complaints were determined to be iron and Mn precipitation and dissolved carbon dioxide (cloudy complaints). The City considered multiple alternatives for addressing the iron and Mn, including installing individual filters at residents’ homes. They estimated the initial cost of filters to be $200 - $500 per affected customer and replacement filters would cost $20 apiece. The filters would need to be replaced every three to six months. The literature does not appear to contain information on utility costs for compensating customers for items stained during laundering or other costs for replacing household equipment specific to issues associated with legacy Mn. As described in an issue paper by Dickinson and Pick (2002), in industrial cooling systems, Mn scales degrade heat exchanger performance and are commonly believed to promote corrosion due to formation of under-deposit conditions. (Under-deposit refers to conditions where a deposit causes a localized concentration of specific chemical promoting accelerated corrosion.) The direct galvanic action of manganese dioxide in the corrosion process is less well recognized and can promote severe localized attack. Manganese deposition in cooling water circuits degrades corrosion resistance, lowers heat exchanger efficiency, and reduces biocide performance. These effects incur significant costs to the electric power industry through increased fuel consumption, more frequent and extensive cleanups, higher chemical treatment costs, and in some cases, significant capital costs for component replacement. The authors state that concerns over Mn fouling are less universal than those related to calcium, silica, or iron due to the often low or undetectable levels of Mn in cooling water supplies. The corrosive impact of Mn deposition in systems relying on these waters can lead to the necessity of replacing condenser tubing, causing expenses that far exceed costs associated with the more common mineral scalants. Manganese deposition is often present as a thin film on plastic pipe or cement-lined pipe, resulting in diameter reduction, or can become incorporated into the corrosion scale of cast iron

©2015 Water Research Foundation. ALL RIGHTS RESERVED. pipes (see Figure 2.5), resulting in increased roughness and increased in pipe friction which is represented by a decrease in the Hazen-Williams C-factor. These phenomena can result in lower pressures and/or increased energy requirements associated with pumping.

Source: Courtesy of Confluence Engineering Group

Figure 2.5 Manganese coating on a galvanized pipe specimen

There is limited documentation on the degree to which legacy Mn can reduce C-factors in distribution system pipes. However Grob (2004) described in a trade journal the results from air scouring water mains of a small Ohio town which had experienced Mn deposition in its distribution system. C-factors were measured in an 8” pipe section before and after air scouring. After removal of the Mn containing solids by air scouring the C-factor improved from 67 to 96 signifying that, in part, legacy Mn was responsible for some of the reduction in C-factor. (Greater C-factors indicate less pipewall friction. Less pipewall friction creates less resistance to the movement of water). However it is impossible to determine from the information provided how much of the reduction in C-factor was directly caused specifically by Mn deposition compared to that caused by corrosion products in general. Grigg (2010) investigated the secondary effects of corrosion control on distribution system equipment. As the authors noted, the Mn problems experienced by utilities are not related to corrosion control, but Mn is interrelated with other effects of deposition and accumulation. Table 2.5 presents Grigg’s analysis of scaling impacts to distribution system equipment.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 2.5 Impacts of scaling to distribution system equipment Equipment Impacts Caused by Scale Beginning with tuberculation in unlined cast iron Pipes pipes, all raw and treated water supply pipes are subject to some form of corrosion and/or scaling. Pumps are vulnerable to failure due to excessive Pumps scaling. Scales can cause problems ranging from lower efficiency to outright failures. Due to the presence of moving parts (similar to Valves pumps), valve function can be inhibited or blocked by scales. Loss of accuracy and periodic meter replacement Meters are caused by scaling (and corrosion). Source: Adapted from: Grigg 2010. Reprinted with permission of the Water Research Foundation.

Cost of Prevention

Kohl and Medlar (2006) report that the median and 90th percentile of treated water Mn leaving the water treatment plants (WTPs) of the surveyed utilities were 22 and 50 µg/L, respectively. Customer complaints continued to occur even in systems at the median level, presumably due to a combination of periodically mobilized legacy Mn and the SMCL being too high to consistently control aesthetic issues. Thus, even for utilities that have Mn removal strategies in place, Mn still presents an ongoing challenge with regard to customer service. The authors recommend that utilities treat Mn to a level which prevents Mn accumulation in the distribution system as opposed to allowing Mn to enter the distribution system, which may or may not cause water quality problems. Though it is hard to quantify, the authors indicate that prevention will save money on customer service calls and flushing. There are numerous engineering reports describing the cost of new treatment associated with addressing water quality problems such as Mn. However, Kohl and Medlar (2006) developed a cost model for addressing Mn through treatment. This model reviewed costs associated with using different treatment processes to reach varying concentrations in finished drinking water. As part of this model, the costs associated directly with treating Mn and operational costs due to Mn treatment were estimated in addition to the consumer benefit associated with preventing Mn problems in the distribution system. The cost model includes assumptions and inputs such as influent concentration of Mn, a treated water target for Mn concentration, per capita consumption costs, unaccounted-for-water, plant sizes, industrial consumption, population served by a given plant size, estimate of the number of persons who may experience problems at a Mn concentration of 50 g/L, and cost to an individual consumer if problems with Mn are experienced in the household. Kohl and Medlar (2006) made a estimate that one percent of the residential population may experience staining, discoloration, or sediment. The researchers assigned an individual cost of $150 per year for consumers affected by Mn problems. This number was developed by considering the costs of direct impacts such as lost and destroyed clothes, purchasing bottled water, attending meetings, cleaning the clothes and dish washers, and etc. and indirect impacts of aggravation and loss of consumer confidence. This study determined that the source of Mn does not affect treatment cost. According to the cost

©2015 Water Research Foundation. ALL RIGHTS RESERVED. model, the researchers concluded that each individual dollar spent by the utility to prevent Mn problems in the distribution system results in a greater benefit to the customer versus if customers had to deal with Mn problems on an individual basis.

Cost of Mitigation

These are costs associated with addressing Mn once it has entered the distribution system and become problematic. Manganese mitigation in the distribution system includes measures such as flushing or pipe cleaning. Hasit et al. (2004) conducted a detailed cost and benefit analysis associated with utility flushing programs. The objectives of this study were to identify the performance parameters for assessing the water quality benefits of flushing operations and to evaluate the costs and benefits of flushing. It is important to note that the study did not specifically focus on flushing effectiveness for Mn removal, and depending on the type of legacy Mn present (loose sediment, adhered film, co-mingled with iron scale) the effectiveness of flushing at removing the Mn will vary substantially. Hasit et al (2004) provides metrics that can be used to develop system-specific basic unit costs, such as:

 Production cost of water flushed.  Disposal cost of water flushed.  Average labor costs.  Average cost of operating vehicles.  Total cost of flushing equipment.

In addition to the Hasit et al. (2004) report, additional flushing cost estimates are available for systems that have found Mn to be a component of their water quality issues in the distribution system. A utility in Alaska conducted a pilot flushing project which improved distribution system water quality, including significantly lower total Mn levels measured at the hydrant. To conduct unidirectional flushing of 16,160 feet of water main, 328 hours of field work and planning were completed. This project also made an estimate of the amount of time needed to conduct planning and fieldwork for future unidirectional flushing efforts and the cost of new equipment. A medium-sized utility in Washington (HDR 2008) conducted a pilot flushing program in December 2007. This effort involved flushing approximately 6 miles of distribution system mains. As part of this effort, estimates were made regarding the number of hours necessary for conducting further flushing of the distribution system. As shown in Table 2.6, the estimate differentiates between the amount of effort necessary to conduct flushing the first time and the amount of effort needed to conduct repeat flushing of an area.

Table 2.6 Estimated hydrant flush labor efforts First Effort Repeat Effort Department (Hours per Mile) (Hours per Mile) O&M – Water 37.4 30.7 Engineering/GIS 11.4 0.0 Public Information 0.8 0.8 Overall 49.6 31.5

Kohl and Medlar (2006) point out that while utilities are responsive to public pressure, it is difficult to justify additional treatment to meet the objective of reducing customer complaints if the water quality meets the SMCL of 0.050 mg/L. However, Kohl and Medlar (2006) point out that while indirect costs to both utilities and customers are difficult to quantify, it appears that most customers would be willing to pay more for water that is aesthetically acceptable the majority of the time. Especially because many consumers tend to use taste, odor, and appearance as surrogates for safety of the drinking water supply (which was justified with respect to Mn presence by Schlenker et al. 2008). Hasit et al. (2004) tried to include indirect impacts in the cost benefit analysis of flushing. The investigators include an evaluation of the benefits of reducing customer complaints, improving water quality, and meeting regulatory requirements.

Aesthetic Impacts and Customer Acceptability

Historically, legacy Mn has been perceived as a nuisance contaminant because of its ability to aesthetically degrade water quality at relatively low levels. Even today, most utilities’ perception of whether they have a “Mn problem” is attributable to customer complaints about discoloration, color, staining, and/or taste. Customers rely on their observations (taste, smell, and appearance) of drinking water at the tap as an indicator of the safety of the water supply. As a contaminant that impacts drinking water aesthetics, Mn control is important for meeting customer criteria of a drinking water that appears safe to drink. Additionally, few customers will find a water supply that negatively affects their ability to launder clothing to be acceptable, even on an intermittent basis. Kohl and Medlar (2006) state that customer complaints continued to occur even in systems at the median level of 20 g/L, presumably due to a combination of periodically mobilized legacy Mn and the secondary MCL being too high to consistently control aesthetic issues. The authors note that Mn presence in drinking water can cause “black water” or dirty water complaints, clothes and fixture staining, and, at relatively high levels, a metallic taste. These problems are caused by particulate Mn (Mn(IV)). In one common scenario, Mn enters a household tap in the dissolved, Mn(II) form, but is oxidized to Mn(IV) by bleach and hot water, resulting in stained clothing. As described earlier, Madison, Wisconsin experienced problems with high levels of Mn at household taps. Investigators found a positive relationship between Mn and the turbidity of flushed drinking water (Schlenker et al. 2008). They found that the average Mn level observed at a turbidity of 1 NTU (criteria for determining an area had been adequately flushed) was 82 g/L and none of the samples with a turbidity of 1 NTU had Mn levels greater than 300 g/L (EPA’s HAV). In samples which had a turbidity of 5 NTU (which were visibly discolored or cloudy), Mn concentrations were greater than 1000 g/L (the 1-day and 10-day HAVs for adults). These results supported the public information campaign to advise people to avoid drinking discolored or dirty water (Schlenker et al. 2008). Two publications were identified recommending a more stringent goal of 0.01 mg/L for Mn compared to the EPA SMCL. These are summarized in Table 2.7. In addition to these recommended levels, both Ljung and Vahter (2007) and Bouchard et al. (2011) recommend that international Mn guidelines be revisited.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 2.7 Literature recommendation for finished water Mn levels of 0.01 mg/L Treatment objective Source Notes The median treated water concentration reported from the National Inorganic and Radionuclide Survey Control aesthetic Knocke (NIRS) found that 68% of the groundwater public problems (2004) water systems (PWSs) reported detectable levels of Mn, with a median concentration of 0.01 mg/L (EPA, 2003) Control Mn Kohl and Manganese deposition in distribution systems can deposition Medlar (2006) occur at concentrations as low as 0.02 mg/L.

Utility Uncertainty

Releases of legacy Mn and co-occurring contaminants can have a negative impact on the utility’s efforts to ensure a safe drinking water supply. Additionally, a utility with legacy Mn in their distribution system cannot predict upcoming releases and, as a result, is typically in a response mode when it comes to Mn. The utility will not know there is a problem until receiving customer complaints. This might lead to wide-spread, unplanned flushing efforts, unplanned pipe cleaning efforts, public outreach and education, and possibly rate increases associated with implementation of mitigation strategies. The unpredictable release of Mn (and co-occurring contaminants) into the distribution system can also negatively impact public confidence in the water provider. This lack of confidence can have far-reaching repercussions on the utility’s public information and educational efforts and other aspects of effective utility management. For example, some utilities have avoided implementation of proactive valve and hydrant exercising programs so as to avoid stirring up accumulated sediments and creating discolored water episodes. The lack of these preventative maintenance programs can expose utilities to uncertainty during emergency situations such as fires or main break episodes, since it may be difficult to locate or operate valves that have not been exercised. Purposeful removal of accumulated legacy Mn and accumulated sediments through ongoing hydrant and valve exercising that typically accompanies a well-organized unidirectional flushing program can enhance utility certainty and responsiveness during emergency episodes.

Remediation and Prevention Strategies

To date, most studies involving Mn have revolved around lowering the amount of Mn entering the distribution system thereby reducing the possibility of a Mn-related colored water episode. Less research has focused on managing the consequences of Mn after it has entered the distribution system. Once Mn has entered the distribution system, techniques for managing the consequences of its presence are few. In this section methods for controlling a) the amount of Mn entering distribution systems and b) mitigating the effects of Mn once it is present in the distribution system are discussed.

Manganese Control Technologies

Numerous water treatment technologies or processes are capable of controlling or removing Mn from source water. Kohl and Medlar (2006) provide an excellent summary of Mn removal and treatment technologies. In their review Kohl and Medlar (2006) classify Mn removal technologies into the following categories:  In situ.  Biological.  Chemical oxidation/physical separation.  Oxide-coated media.  Physical separation.  Ion exchange.  Incidental precipitation (softening).  Sequestration.

While not a removal; technique, blending is another effective method for controlling Mn concentrations entering the distribution system. Table 2.8 summaries key Mn treatment techniques and their basis of operation.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 2.8 Summary of Mn treatment techniques Treatment Category Subcategory Basis of Operation Full lake or hypolimnetic aeration to suppress release of Surface water soluble Mn from anoxic lake or reservoir sediments into the water column. Adjustment (increase) in redox potential caused by injection In-situ of oxygenated water within zone of influence of withdrawal aeration well. Injected water creates conditions that form insoluble Groundwater Mn(IV) in the native groundwater. The Mn(IV) is retained in aquifer materials when the native water is withdrawn for use. Biological oxidation of Mn(II) under aerobic conditions Biological forming insoluble Mn(IV) which is retained by the biofilm or substrate material.

Oxidation of Mn(II) by chemical oxidants to insoluble Chemical Chlorine Mn(IV). Oxidation is typically followed by physical oxidation/ Permanganate separation of particulate Mn(IV) from the treated water physical Ozone using one of several processes. Effective solid/liquid separation Chlorine dioxide separation processes include sedimentation/media filtration and low pressure membranes.

Reverse Soluble Mn(II) in its ionic +2 state is separated from source Physical osmosis/nano water when water is passed through a polymeric membrane separation filtration membrane under pressure. Glauconite sand is pre-coated with MnO2(s) and activated by permanganate or chlorine. Mn removal is by a two step Greensand process of Mn(II) adsorption followed by oxidation to Mn(IV) at the sand’s surface. Mineral MnO2 (pyrolusite) is used rather than pre-coated Pyrolusite glauconite sand. Soluble Mn removal mechanism is Oxide-coated similar. media Existing filter media is coated in-situ by MnO2(s) in the presence of chlorine using background Mn in the source Induced oxide-coated water or short term exposure to permanganate. After in-situ media coating, soluble Mn is then removed per the mechanism similar to greensand and pyrolusite. Media is continuously or intermittently regenerated in the presence of chlorine. (continued)

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 2.8 (Continued) Treatment Category Subcategory Basis of Operation Soluble Mn(II) is removed by a cation exchange process in Ion Exchange which Mn2+ replaces hydrogen or sodium ions on active sites on the cation exchanger. Lime or hydroxide addition (softening) increasing treated Incidental water pH to 9.5 or greater causing precipitation of insoluble precipitation Mn. Insoluble Mn is incorporated into softening solids and (softening) removed by sedimentation and filtration. Addition of sequestering agents (typically polyphosphates) that maintain Mn(II) in solution by binding Mn(II) to sequestrant and delaying oxidation of Mn(II) to insoluble Mn(IV) for the period of time that the treated water remains Sequestration in the distribution system. Unlike other processes, sequestration does not remove Mn from the treated water and Mn may release (become unbound) as sequestrant degrades.

Readers who desire to obtain additional information regarding treatment techniques are encouraged to consult Kohl and Medlar (2006) or Casale et al. (2002). AWWA Water Quality and Treatment, a Handbook on Drinking Water (2011) and AWWA Water Treatment Plant Design (2012) are also excellent resources for the interested reader. The recently published, Guidance for the Treatment of Manganese (Brandhuber et al., 2013), should be consulted as well.

Prevalence of Treatment Technologies

There are no comprehensive surveys of water treatment facilities that have determined the prevalence of particular Mn treatment technologies. Casale et al (2002) performed a survey of Mn treatment technologies at 101 surface, groundwater and surface and groundwater blend plants operated by American Water Works Services Company. Of the approximately 50 surface water plants surveyed (the exact number of surface water plants surveyed was not stated) 47 plants practiced chemical oxidation, with the remaining plants practicing aeration or sequestration. Groundwater plants used a wider variety of treatment technologies. Of the approximately 50 groundwater plants surveyed (again the exact number of groundwater plants surveyed was not stated), 11 used aeration, 26 chemical oxidation, 11 oxide-coated media, 19 sequestration and 3 other processes. It is evident that some of the groundwater plants are using multiple processes for treating Mn. It should be noted that the large number of reported aeration systems were actually for iron treatment and not Mn removal. Casale et al (2002) also analyzed the 1996 AWWA WaterStats database and concluded that of 492 groundwater systems, 28.5% used permanganate, 18.1% used iron and Mn control processes and 6.9% used oxide-coated media. For 543 surface water systems surveyed for WaterStats database, Casale et al (2002) concluded 35.7% used permanganate, 7.9% used iron and Mn control processes and 0.2% used oxide-coated media. In both cases it is not clear if permanganate addition was for Mn control or other treatment objectives. Nor were details of the ‘iron and Mn control’ technologies were specified.

Distribution System Mitigation

As described in the previous section, Mn can be controlled or removed from source waters by several different methods and technologies. Nonetheless, it is very likely that trace amounts of Mn will find its way to the distribution system. This is due in part to the limitation of each treatment methods or to the initial understanding that Mn is not a problem at all (i.e., Mn is present at levels below the secondary MCL of 0.050 mg/L and consequently the water utility has not implemented a plan for Mn control/removal ). To mitigate problems caused by Mn reaching distribution systems, water utilities can implement several strategies including a) periodic flushing; b) pigging distribution lines; c) chemical addition for finished water stabilization; and d) pipe replacement. Periodic Flushing. Pipe flushing consists of forcing high velocity water through the distribution system with the purpose of dislodging and removing precipitates. The use of periodic flushing by water utilities to mitigate and prevent the accumulation of precipitated materials in the distribution system has been widely employed (Chadderton et al. 1993; Friedman et al. 2002; Hasit et al. 2004; Husband et al. 2008; Kohl and Medlar 2006; Schock et al. 2005). Hasit et al (2004) conducted a detailed cost and benefit analysis associated with water utility flushing programs. Moreover, the investigation identified the performance parameters for assessing the water quality benefits of flushing operations. The researchers found that the majority of utilities surveyed utilize some type of flushing program on a yearly basis to primarily address and minimize customer complaints. Concurring, Kohl and Medlar (2006) stated that consumer pressure is typically the driver for utilities to employ or modify Mn treatment and/or implement distribution system mitigation practices such as flushing. Although periodic flushing is a common practice, it does not guarantee successful results. Schock et al (2005) reported that Hopkinton, Mass., continued to receive red water complaints even after instituting a flushing program to eliminate precipitated iron from the water mains. Pigging Distribution Lines. Pigging consists of pushing an object, termed a pig3, through the water distribution line to dislodge and carry away precipitated solids. Similar to flushing, pigging has also been extensively employed by water utilities to mitigate the accumulation of precipitated materials in the distribution system. The different types of pigs used for pipe cleaning in drinking water applications as well as their classification and pig launching methods are described elsewhere (Huben 2005). However, to the authors’ best knowledge; there is no peer-reviewed literature that has investigated pigging performance and costs associated with using this mitigation technique to control legacy Mn. Finished Water Stabilization. In theory, by reducing desorption and dissolution episodes, finished water stabilization can be employed to mitigate distribution systems affected by Mn accumulation. As presented in Table 2.9, Friedman et al, (2010) summarize water quality conditions that can impact deposit and trace contaminant stability.

3The term pig is derived from the term Pipeline Inspection Gauge. Pigs are designed for a number of uses; in this case the reference is to a cleaning pig.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 2.9 Water quality conditions that impact deposit and trace contaminant stability Water Quality Characteristic Description of Impact The following processes are highly sensitive to pH: adsorption and desorption of trace elements; precipitation/solubilization of precipitates capable of serving as accumulation sinks; Provide a stable pH within the precipitation/solubilization of trace contaminant compounds; distribution system (±0.2 units) and deposit stability. When implementing purposeful pH adjustment, utilities should be aware of potential release impacts and perform distribution system monitoring. Provide a stable oxidation- The nature and stability of mineral deposits is dependent on ORP. reduction These include deposits that may serve as accumulation sinks potential (ORP) within the (e.g., FeCO3, α-FeOOH), as well as chemical precipitates distribution system (± 20%) directly involving trace elements (e.g., Cr(OH)3, PbO2, UO2). Orthophosphate can react with common inorganic elements to produce precipitates that may serve as accumulation sinks or low-solubility passivation layers. In either case, it is important to Provide a stable orthophosphate maintain a near-constant concentration to promote stability of concentration within the these solids. distribution system (± 20%) When implementing purposeful phosphate addition, utilities should be aware of potential release impacts and perform distribution system monitoring. Reduce the formation of iron corrosion scale and tubercles. Provide adequate corrosion Reduce the occurrence of red water episodes. control Promote the stability of cement-mortar linings. Reduce the leaching of inorganics from cementitious materials. Groundwater and surface water supplies typically have very different water quality profiles, including mineral/ionic distribution, NOM concentrations, and ORP. The uncontrolled Avoid uncontrolled blending of blending, or periodic switching back-and-forth, of these different surface water and groundwater source types can prevent formation of stable corrosion scales and contribute to the release of existing scales and associated contaminants. Avoid uncontrolled blending of The uncontrolled blending, or periodic switching back-and-forth, free chlorinated and can cause dramatic changes in ORP and disinfectant residual chloraminated water type and concentration, thus impacting scale stability. Source: Friedman et al. 2010. Reprinted with permission of the Water Research Foundation.

Pipe Replacement. Although not specifically used to mitigate legacy Mn accumulation in water distribution systems, pipe replacement has been used by water utilities for a long time to solve iron pipe corrosion issues (McNeill and Edwards 2001). Thus, pipe replacement could be a very effective technique used as a last resort for water utilities that have a severe case of metals accumulation in their distribution system, although it would only be an effective long-term solution if coupled with a rigorous control optimization program at the treatment plant. Metals accumulation could then be integrated into a Capital Improvement Plan (CIP) that governs pipe replacement for a specific utility.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Management of Legacy Mn Residuals From Flushing. Potentially, residuals management could be an important factor when mitigating legacy Mn in distribution systems. It is a common practice to allow the flushed liquid/solid material to flow to the nearby storm water run-off drain, as there is no established procedure governing the disposal of such residuals. However, this scenario could change and it might be necessary to investigate and classify the type of solid residuals produced when mitigating legacy Mn and verify if the residuals pass the Toxicity Characteristic Leaching Procedure (TCLP) as co-contaminants might be present as well. This could be useful in setting a standard procedure to capture, dewater, and dispose the solid material to a landfill and comply with potential future regulations.

CONCLUSIONS

 Legacy Mn is a wide-ranging topic touching on many areas: chemistry, treatment, costs, consumer confidence and potentially health effects. Based on information gathered for this review, several observations are made regarding legacy Mn and its relevance to the water treatment industry.  Because of its costs to utilities, impact on consumer confidence and possible, but unproven detrimental impact on public health, legacy Mn is an issue worthy of the drinking water industry’s attention.  The complexity of Mn chemistry along with inherent features of distribution systems (spatially covering a large area, variations in infrastructure age, design features, time varying hydraulics, time dependent changes in water chemistry), suggests that it is more difficult to control accumulation and release in the distribution system than to prevent entry of Mn into the distribution system. However even the most effective treatment system will still permit trace levels of Mn to enter the distribution system.  It is likely that utilities tend to underestimate the cost impacts of accumulated Mn. In general, utilities consider the cost impacts of accumulated Mn as an O&M expense rather than a problem to be solved by capital improvements.  Mn episodes seriously erode customer confidence in a utility. The erosion of consumer confidence is generally not considered by utilities in estimating the cost of accumulated Mn.  Utilities could benefit from more information on the direct and indirect costs associated with legacy Mn. Further information could assist in selecting appropriate treatment and/or prevention measures and in educating consumers on the costs and benefits of spending capital and/or maintenance dollars on addressing legacy Mn.  On average, the percentage on a weight basis of accumulated Mn in pipe scales is small. However, percent weight analyses represent relative occurrence and must be interpreted with caution. There are wide variations in the amount of accumulated Mn in distribution system.  Available data indicate that accumulated Mn may be spatially localized in distribution systems (as opposed to being uniformly distributed throughout the distribution systems). If true, localized control of Mn in the distribution system, which focuses on the Mn impacted zone, rather than system wide control should be considered as an approach to deal with legacy Mn.

©2015 Water Research Foundation. ALL RIGHTS RESERVED.  Some research appears to show that Mn impacts on public health may need to be revisited. These public health impacts may be caused directly by Mn exposure (as demonstrated in Bouchard et al. 2011) or through exposure to other contaminants that can negatively affect public health and which are found to co-occur with Mn.

DESCRIPTION OF SURVEY

A survey of the project’s participating utilities was performed to gather the information required to quantify the potential impacts of accumulated Mn. The objective of the survey was to improve the understanding of problems caused by Mn that has previously accumulated and is accumulating in water systems. Ten utilities from across the country participated in the study, including: Arvada, CO, Boulder, CO; Lacey, WA; Moscow, ID; Newport, OR; Newport News, VA; Park City, UT; Philadelphia, PA; Renton, WA, and United Water (Boise), ID. Each participating utility committed to various levels of in kind services to complete the survey and to provide information on their system to the research team. A Utility Survey Questionnaire was prepared and distributed to each utility. The questionnaire requested general background information on each utility and detailed information regarding the source of water supply, the type of treatment used, disinfection strategy, water quality concerns, the average daily production, and number of service connections and estimated population served. Several parameters were requested regarding the distribution system including total length, number of pressure zones, number of points of entry to the system, predominant pipe material and several questions regarding the operation and maintenance program. Each point of entry to the distribution system that has been linked to Mn was identified and described. A copy of the Utility Survey Questionnaire is provided in Appendix A for reference.

OVERVIEW OF SURVEY RESULTS

A summary of the background information, water quality information related to Mn, and distribution system information of the participating utilities is presented in Table 3.1. Survey results demonstrated the considerable history of Mn in the participating utilities. The average daily water production of these utilities ranged from 2 to 245 mgd, serving estimated population ranging from 7,500 to 1.6 million in addition to varying wholesale water demands. Source water for these utilities include 100% surface water, 100% groundwater, groundwater under direct influence (GWUDI), or surface water and groundwater blends at various magnitudes. Most of the participating utilities have more than one raw water source, with as many as 78 sources at one utility. Similarly, the number of points of entries (POEs) to the water systems ranged from one to 78. The treatment processes to treat source water include: disinfection only, conventional treatment, greensand filtration, ozonation, dissolved air flotation, preoxidation, ozonation and sequestration. Conventional treatment is defined as using mixing, flocculation, sedimentation, filtration, and disinfection unit processes primarily for turbidity removal and disinfection. Over half of the utilities reported to have a process designed to remove Mn in their treatment facilities. The average concentration of Mn at the point of entry of the utilities ranged from non-detectable levels to 0.46 mg/L. Most of the participating utilities recycle filter backwash water, which results in Mn recirculation within the treatment plant. Other raw water

©2015 Water Research Foundation. ALL RIGHTS RESERVED. quality issues that these facilities experience include the presence of total organic carbon, sulfate, hardness, iron, arsenic, and ammonia as well as seasonal taste and odor. Distribution systems range in size from approximately 70 to 3,000 miles of pipe and include between one to 48 pressure zones. Approximately half of the distribution system pipelines are of cement-lined and plastic (PVC/HDPE). The utilities have a water storage reservoir capacity ranging from 4.75 to 271 million gallons (MG) and have a maximum residence time ranging from one day to 20 days. Nearly all of the utilities could identify specific zones within their distribution system that are disproportionately impacted by Mn. Most utilities in the study use chlorine as the primary disinfectant and either chlorine or chloramines are used to provide residual disinfection. The utilities maintain an average disinfectant residual ranging from 1.5 to 3.0 mg/L with chloramines and from 0.5 to 1.5 mg/L with chlorine. Under current treatment conditions, over half of the participating utilities have experienced discolored water episodes in their distribution systems, ranging from 1 to 45 episodes per year. Approximately, one quarter of these discolored water episodes occur in the parts of the distribution system that are more vulnerable to Mn accumulation and/or release. Seven of the ten utilities in the study have a response plan for addressing these episodes. Flushing the distribution system pipelines near the discolored episode location appears to be the most accepted response plan for the utilities. Seven of the ten participating utilities have a preventative flushing program in place, seven also have a reactive flushing program and two do not perform any flushing. Six of the ten participating utilities track hours spent dealing with customer complaints related to Mn in their distribution system. About one third of the utilities have had to pay damages or make restitution to customers because of Mn staining or other impacts caused by Mn release. Two of the ten participating utilities had entered into a public relations campaign because of Mn or discolored water episodes. Two of the ten utilities experienced equipment- fouling issues within the distribution system due to Mn accumulation. All the utilities reported that the cost-incurring impacts of the Mn accumulation or release in their distribution systems are due to flushing, sampling, and time spent responding to customer complaints. None of the participating utilities reported losing customers following a Mn episode. Approximately half of the participating utilities have abandoned a water source due to Mn. Only one utility reported regulatory compliance issues related to Mn release. A detailed summary of utility survey responses are presented in Tables B.1–B.4 of Appendix B.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 3.1 Summary of the background information, water quality information related to Mn, and distribution system information as reported by the participating utilities1

Average Specific Average Mn Number Storage Daily Unique Points Treatment Concentration of Tank Population Production Water Of for Mn at POE Miles Pressure Capacity Utility Served (MGD) Supplies Entry Treatment Process Type (Y/N) (mg/L) of Pipe Zones (MG) Surface Water Systems 7.45*/15.9 Arvada, Co 105,000 3 2 Conventional No 0.057 531 5 14 7 Conventional/Dissolved Boulder, CO 166,000 15.4 4 2 No 0.46 456 3 35 Air Flotation Conventional/Seasonal Newport, OR 10,000 2.5 1 2 Yes 0.06 73 3 6.5 Mn Removal Philadelphia, 1,526,000 244.5 2 3 Conventional Yes 0.002 3,145 11 271 PA Ground Water Systems

Disinfection Moscow, ID 24,500 2.17 5 4 Yes 0.1* 93.3 5 4.75 only/greensand Filtration

Park City, UT 7,500 4 7 7 Oxidation/Disinfection No 0.01 100 48 12.65

Oxidation/Greensand Renton, WA 86,230 6.7 6 3 Yes 0.004 305 13 4.75 Filtration/Disinfection Mixed Surface and Ground Water Systems Disinfection only/Fe-Mn Lacey, WA 67,000 7.02 19 16 No 0.01 357 7 13.1 Removal Newport Conventional/Ozone 415,000 34 3 2 Yes 0.0011 1,743 2 35 News, VA Disinfection United Water, Sequestration/Greensand 227,000 38.4 78 78 Yes ND 1,195 10 38.7 ID Filtration (continued)

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 3.1 (Continued) Avg. Annual Annual Disinfectant Disinfectant Discolored Mn Preventative Reactive Track Hours Residual Residual Water Related Flushing Flushing Response Responding to Utility (mg/L) Type Episodes Episodes (Y/N) (Y/N) Plan (Y/N) Complaints (Y/N) Surface Water Systems Arvada, Co 1.5 Chlorine < 1 < 1 Y Y Y Y

Boulder, CO 0.9 Chlorine -- -- Y** N N N

Newport, OR 0.7 Chlorine -- -- N N N Y Philadelphia, 1.5 Chloramines -- -- Y*** ( N N N PA Ground Water Systems Moscow, ID 0.5 Chlorine 50 -- Y Y Y Y Park City, UT 0.5 Chlorine 3 1 Y Y Y N Renton, WA 0.9 Chlorine 3 0 N N N Y Mixed Surface and Ground Water Systems Lacey, WA 0.56 Chlorine 5 4 Y Y Y Y Newport 3 Chloramines 103 5 Y Y Y Y News, VA United Water, 0.6 Chlorine 151 45 Y Y Y Y ID 1. Data provided above reflects utility survey responses that were completed in 2011. *Average production at the POE with greatest Mn concern **Not routinely implemented *** For stabilizing disinfectant residual not Mn

Arvada, CO

The city of Arvada, Colorado is located in the northwest portion of the greater Denver metropolitan area. It serves water to an estimated population of 105,000. Arvada’s water system includes two WTPs, the Ralston WTP and the Arvada WTP. Arvada’s water supply is comprised completely of surface water. The Ralston WTP obtains its raw water from Ralston Reservoir, which is supplied by mountain runoff originating in the high Colorado Mountains on the western slope of the continental divide. The water is imported to the metro area through a series of tunnels and reservoirs. The Arvada WTP is supplied by the Arvada/Blunn Reservoir, which receives water from Clear Creek and Ralston Reservoir. The Ralston WTP has a treatment capacity of 36 MGD and is the primary plant operating throughout the year. It has an average production of 13.23 MGD. The Arvada WTP is used to meet peak summer demands and is typically operated May through September. It has a capacity of 16 MGD, an average daily production of 7.45 MGD and a maximum production of 12.8 MGD. Both the Ralston and Arvada WTPs utilize the same conventional treatment process, which includes coagulation, flocculation, sedimentation, filtration, pH adjustment, disinfection using chlorine, and fluoridation. An average of 1.5 mg/L chlorine residual is maintained in the distribution system. The water distribution system is comprised of four different types of water main. Approximately 49% of the distribution system is comprised of PVC pipe material. Thirty-four percent of the distribution system piping is asbestos cement, 13% is cast-iron, and 4% is steel. The distribution system has the capacity of approximately 36 MG of water storage for peak demand. The Arvada system includes approximately 50 million gallons of total storage capacity with the tanks and piping system. The average and maximum residence time in the system is less than three days. In 2007, Arvada’s distribution system had five pressure zones, four gravity fed zones and one pump fed zone. The City of Arvada experienced a Mn related colored water episode in September 2007. Following the colored water episode, the utility performed a study to determine the root cause of the Mn and to modify the operations or facilities to prevent future Mn episodes. The episode was attributed to the Arvada WTP because areas that are served only by the Ralston WTP have not experienced a Mn related problem. Following the study, the utility modified the distribution system to blend the water from the Ralston and Arvada WTPs prior to entering the distribution system. Some water was blended from the 4-3 valve at the Arvada Plant. The water chemistry leaving the two water treatment plants was matched but they still used the two separate entry points into the distribution system. This seemed to stabilize the water chemistry in the distribution system. Additionally, they established unidirectional system-wide proactive flushing program to address Mn build-up in the distribution system. Approximately one-third of the distribution system is flushed per year at a target velocity of five feet per second. Under the current conditions, Arvada rarely receives complaints regarding discolored water episodes.

Boulder, CO

Boulder is located at the base of the foothills of the Rocky Mountains approximately 30 miles northwest of Denver, Colorado. It serves an estimated population of 166,000. The City of

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Boulder owns and operates two WTPs, the Boulder Reservoir WTP and the Betasso WTP. Both WTPs are operated and maintained throughout the year. The Betasso WTP is the base loading plant and the Boulder Reservoir WTP supplements increased water demands throughout the year. Each WTP has a separate point of entry into the distribution system. Boulder’s raw water supply consists of 100% surface water. Raw water is supplied to the Betasso WTP from Barker and Lakewood Reservoirs. These reservoirs capture water from local watersheds on the eastern slope of the continental divide. Raw water for the Boulder Reservoir WTP consists primarily of water diverted from the upper Colorado River on the western slope of the continental divide. This water is delivered to northeastern Colorado through a series of tunnels, canals and reservoirs and stored in the Boulder Reservoir. Raw water is supplied to the Boulder Reservoir WTP from Boulder Reservoir for most of the year. However, from May through October, raw water is occasionally obtained directly from the canal supplying Boulder Reservoir. Together, the Betasso and Boulder Reservoir WTPs have the capacity to treat approximately 48 MGD, the average daily production is 15.4 MGD and the maximum daily production is approximately 33.6 MGD. The Boulder Reservoir WTP is typically operated at flow rate of 4 MGD. Water treatment at both WTPs includes pre-disinfection, coagulation, flocculation, dissolved air flotation, filtration, post-disinfection using chlorine, corrosion control, and fluoridation. An average of 0.9 mg/L disinfectant residual is maintained in the distribution system. Boulder’s distribution system includes approximately 456 miles of piping divided into three pressures zones. Boulder has 35 million gallons of storage capacity and has an average residence time of one day and a maximum of three days. Boulder has had a history of complaints related to discolored water and staining. The utility accredits Mn issues to anoxic sediment conditions during the summer months in the Boulder Reservoir. Dissolved Mn in turn passes through the Boulder Reservoir WTP to the distribution system. In 2001, the intake at the Boulder Reservoir was modified to avoid obtaining anoxic water from the bottom of the reservoir, which alleviated the discolored water episodes. Complaints have recently re-emerged and are being attributed to an increase in the use of raw water from the Boulder Reservoir. The utility does not currently have a response plan to address the colored water episodes. They have established a unidirectional flushing program; however, it is not implemented on a routine basis. The utility tries to address the Mn build-up issues in the distribution system by controlling Mn before entry to the distribution system.

Lacey, WA

Lacey, Washington is located in the eastern portion of the greater Olympia metropolitan area. The City of Lacey serves drinking water to approximately 67,000 residents. The water supply is almost exclusively groundwater from 19 local wells, although during this study it was augmented by City of Olympia surface water to meet peak demands. There are 16 separate points of entry into the distribution system. The wells have varying concentrations of naturally occurring iron and Mn. Well water is disinfected at the wellhead using chlorine, with an average disinfectant residual of 0.6 mg/L. Lacey treats two wells for iron and Mn. The Lacey’s water system has an average daily production of 7 MGD and a maximum daily production of 15.7 MGD. Each well is a separate point of entry (POE) into the distribution system. The distribution system includes approximately 360 miles of pipe, of which approximately 64% is plastic (PVC or HDPE), 23% is concrete/transite (AC), and 13% is cement lined ductile iron. The distribution

©2015 Water Research Foundation. ALL RIGHTS RESERVED. system includes seven primary pressure zones. Low levels of dissolved iron and Mn are precipitated in the distribution system, which is flushed annually. Most of the Mn specific zones include the older areas of the Lacey water system, which have AC pipe. Lacey has a history of colored water episodes dating back to 1979 when untreated wells containing dissolved Mn and iron were put into service. Complaints related to staining, taste and odor, were initially localized to the vicinity of the point of entry (POE) with the highest concentrations of Mn and iron and in areas of high water age. At that time, Lacey was an unfiltered and unchlorinated system and the city would receive colored water complaints when chlorinated water from the intertie with the City of Olympia was used for peaking. However, the complaints gradually increased in the late 1990’s and were widespread and frequent by 2002- 2003. In response to these frequent discolored water episodes, the City has constructed two iron and Mn removal treatment plants in 2001 and 2008 at the highest iron and Mn source wells. Prior to treatment from a filtration plant, one source was blended in a 4 MG reservoir to dilute Mn and sulfide in the water. However, blending ceased to be an option after 2005 when system-wide chlorination started, because blended water became discolored in the reservoir. They also removed one source that had high Mn from the system. Additionally, the City has established a unidirectional flushing program to address discolored water episodes and implemented chlorine disinfection process at each individual well. Pipelines in the area of high Mn well supplies are flushed annually at a velocities ranging from 6 of 10 feet per second to achieve a turbidity of <1 NTU. Approximately 20% of the remainder of the distribution system is flushed each year. Complaints related to colored water have significantly decreased since filtration and flushing measures were implemented. However, the few complaints that the City receives now are attributed to the Mn build-up as well as iron buildup on the older part of the Lacey’s distribution system.

Moscow, ID

Moscow is located in northern Idaho along the Washington/Idaho border. The City operates a groundwater system for water service to its 24,500 customers with an average daily production of 2.17 MGD and a maximum daily production of 5.1 MGD. The system is comprised of five groundwater supply wells located in the Columbia Basalts. Two of the wells are located in the shallow Wanapum aquifer, while the other three are in the deeper Grande Ronde aquifer. The three Grande Ronde wells discharge to unique points of entry to the distribution system, with average Mn and iron concentrations of 0.06 mg/L and 0.48 mg/L, respectively. These wells receive no treatment for iron and Mn. The two shallow Wanapum aquifer wells have been treated with greensand filtration for iron and Mn removal since the 1970’s. The treated water from these wells enters the distribution system at a shared entry point located at the filter plant. The treated water has average Mn and iron concentrations of 0.05 mg/L and 0.10 mg/L, respectively. Chlorine is added to treated water prior to distribution. Approximately 0.5 mg/L of disinfectant residual is maintained in the distribution system. Moscow’s distribution system consists of 93 miles of pipe, spread over five pressure zones and includes 4.75 million gallons of storage capacity. Residence time in the systems ranges from an average of five days to a maximum of ten days. Pipe materials in the system include lined and unlined cast or ductile iron, unlined steel/galvanized, concrete, cement-lined pipe, and plastic (PVC or HDPE) pipe. However approximately 70% to 75% is lined cast or ductile iron. Under current conditions, Moscow experiences approximately 50 discolored water episodes system-wide per year. Episodes occur year round with greater frequency in the summer

©2015 Water Research Foundation. ALL RIGHTS RESERVED. months. The colored water episodes are attributed to un-filtered groundwater from deeper aquifer wells. A system-wide proactive flushing program is performed bi-annually to address Mn build- up in the distribution system. Moscow flushes the local fire hydrant in response to a colored water episode. The distribution system is flushed at a target velocity of 2-4 feet per second. Moscow also cleans buildup in its largest elevated reservoir using a robot vacuum at intervals of 12 to 18 months.

Newport, OR

Newport is located on the Oregon coast approximately equidistant from the Washington and California state lines. Newport serves a population of approximately 10,000. The water supply is 100% surface water, stored in two reservoirs operated in series. They operate a single WTP with an average daily production of 2.5 MGD and a maximum daily production of 3.9 MGD. Conventional treatment is in place with seasonal, targeted Mn removal using sodium permanganate addition. Chlorine is used for disinfection; an average residual of 0.7 mg/L is maintained in the distribution system. The distribution system includes approximately 75 miles of pipe, spread over three pressure zones and includes 6.5 million gallons of storage. Newport typically receives customer complaints related to colored water after large volumes of water are used, such as a broken pipe or fire. The utility does not currently have a flushing program in place, but they do collect water samples and test for various water quality parameters including iron, Mn and pH when responding to a customer complaint. Newport reportedly has accumulated Mn on the interior of the distribution system piping that is thought to have accumulated prior to the implementation of their sodium permanganate feed program.

Newport News, VA

Newport News, Virginia is located in the southeastern portion of the state on the Virginia Peninsula on the north shore of the James River, northwest of Virginia Beach. Newport News Waterworks serves water to approximately 415,000 people; operating two surface water plants (Harwood’s Mill and Lee Hall) and one reverse osmosis treatment system for a brackish groundwater supply. Surface water comprises 95% of the total water supply; raw water is obtained from Chickahominy River. When available, raw water is pumped from the river, above Walkers Dam, and is transferred to reservoirs for storage. Waterworks owns and operates five reservoirs that store and supply water to the treatment plants. Each surface WTP has its own point of entry into the distribution system. In total, Newport News has an average daily production of 34 MGD and a maximum daily production of 60 MGD. The Harwood’s Mill WTP operates year round providing between 12 to 22 MGD. The treatment process at the Hardwood’s Mill WTP includes conventional treatment, pretreatment oxidation using potassium permanganate and intermediate ozonation. Filter backwash is recycled through the raw water reservoir; recycle is treated using chlorinated greensand filtration. The Lee Hall WTP operates year round to supplement water demands. The Lee Hall WTP has a similar treatment schematic to the Harwood Mill WTP, however treatment at Lee Hall includes biological filtration and the filter recycle stream is treated with polymer to facilitate particle settling in a gravity thickener prior to recycling to the reservoir. Brackish groundwater is pumped to a reverse osmosis system located at the Lee Hall WTP. Treated groundwater is blended with treated surface water at the Lee Hall WTP prior to distribution. Chloramines are

©2015 Water Research Foundation. ALL RIGHTS RESERVED. used to provide secondary disinfection at both WTPs; an average residual of 3.0 mg/L is maintained in the distribution system. The entire distribution system includes approximately 1,700 miles of pipe spread over two pressure zones and includes 35 million gallons of storage capacity. Residence time in the system ranges from an average of one day to a maximum of three days. Most discolored water episodes have been near the Harwood’s Mill WTP. The distribution system material is this area is primarily cement lined (>90%) and includes a small amount of plastic (PVC or HDPE), unlined cast iron, and unlined steel pipe. Newport News had several colored water episodes over the last 20 years. They experience approximately 103 discolored water episodes per year of which five episodes per year are in Mn specific zones. The utility established a reactive flushing program to address customer complaints regarding the discolored water episodes. Colored water episodes have continued, although have reduced in frequency over the years, concurring with treatment upgrades at the two WTPs. Treatment upgrades at the Harwood’s Mill WTP include ozonation addition, the removal of centrate from the WTP recycle, the addition of pretreatment oxidation using permanganate and the addition of greensand filtration for the recycle stream. Mn is present in the distributed water year round. The winter concentration is the highest, with an average of 17 µg/L, the spring season is the lowest with approximately 8 µg/L. Discolored water episodes are addressed by a customer service representative flushing at the nearest hydrant in the area at a minimum velocity of five feet per second until the water is clear.

Park City, UT

Park City is a historic mining community located approximately 30 miles east of Salt Lake City in the Wasatch Mountains. Park City Municipal Corporation (PCMC) serves an estimated population of 8,500. PCMC obtains its water from three wells: one that is under the influence of surface water and is treated with ultraviolet light and sodium hypochlorite disinfection; one spring; two mining tunnels; and one imported treated mine source. Raw water quality issues include high concentrations of iron, Mn, antimony, thallium and arsenic in mine tunnel waters. The average daily production is 4.0 MGD and maximum daily production is 9.0 MGD. The base load demands of the system are met in part by the Spiro WTP, which treats mine tunnel water. This plant has a rated capacity of 3.0 MGD. Treatment includes oxidation utilizing sodium hypochlorite and ferric chloride addition for arsenic reduction. Blending with spring water reduces antimony at the Spiro WTP. Chlorine is also used at all sources to provide residual disinfection, and an average disinfectant residual of 0.5 mg/L is maintained in the distribution system. The distribution system includes approximately 100 miles of pipe and nearly 50 pressure zones, with seven POEs into the system and over 12 million gallons of storage capacity. The distribution system pipeline infrastructure includes 60% concrete/transite, 20% cement lined, 10% plastic (PVC or HDPE), and 10% unlined ductile iron pipe. On an average, the utility experience three discolored water episodes per year of which one episode per year was attributed to Mn. The utility established unidirectional flushing program to addresses Mn build-up in the distribution system at a target velocity of three feet per second. The entire distribution system is flushed annually to minimize iron and Mn accumulation. In response to 2007 and 2010 discolored water episodes, the utility issued a public relations announcement and set up a hot line for customers to check on the status of the episodes. During the discolored water episodes, the utility advised the customers not to drink tap water for a short time because Mn and thallium water sample results were above the respective secondary MCLs and primary MCLs. Since

©2015 Water Research Foundation. ALL RIGHTS RESERVED. 2010, PCMC has been conducting more rigorous unidirectional flushing on a semi-annual basis and has been targeting velocities of 6 feet per second.

Philadelphia, PA

Philadelphia is the largest city in Pennsylvania. It is located in the southeastern corner of the state and shares a border with New Jersey, which is delineated by the Delaware River. The Philadelphia Water Department (PWD) currently serves a population of approximately 1,526,000 with wholesale service to an additional 56,900. PWD operates a surface water system, with an average daily production of 244.5 MGD and maximum daily production of 286.2 MGD. The system is supplied by the Delaware and Schuylkill Rivers. Mn in both sources averages between 0.08 and 0.09 mg/L, with periodic excursions up to 0.5 mg/L. PWD operates three water treatment plants: the Baxter WTP (on the Delaware River), and the Belmont and the Queen Lane WTPs (on the Schuylkill River). Combined, they provide a treatment capacity of 546 MGD. All three of the WTPs are conventional filtration facilities that use pre-chlorination, coagulation with ferric chloride, settling, gravity filtration, zinc orthophosphate for corrosion control, disinfection with chloramines, and powdered activated carbon addition for taste and odor control. All three of the facilities add chlorine upstream of media filters to promote sorption of Mn to the filter media. This method has been successful at the plants, consistently removing Mn to levels below 0.01 mg/L. The utility maintains an average chloramine residual of 1.5 mg/L. PWD’s distribution system consists of approximately 3,145 miles of pipe distributed over 11 pressure zones and is fed by three points of entry to the system, one at each WTP. The majority of the pipelines are cast iron (73%) and ductile iron (24%) with a small percentage of steel and concrete piping. Approximately 45% of the pipelines are cement- lined. Within the system, there are seven finished water storage reservoirs with a combined capacity of 271 million gallons. Residence time in the system ranges from an average of five to a maximum of seven days. Most colored water complaints are for rusty/brown water and correspond with areas that have recently been affected by water main construction or operational activity. The utility performs conventional flushing in the area when a complaint is received.

Renton, WA

Renton is located outside Seattle on the southeastern end of Lake Washington. The City provides water service to a population of approximately 86,000, with customers including major manufacturing and technology companies, such as Boeing, Paccar, and several dot-com companies. The City is also a wholesale water supplier to Skyway Water and Sewer District (formerly Lakeridge Bryn-Mawr Water District). Renton’s water supply is 100% groundwater; approximately, 87% of Renton’s water is supplied by the Cedar Valley Aquifer, with the rest coming from Springbrook Springs, which is located in south Renton. The total water supply has an average water production of 6.7 MGD and maximum daily production of 12.8 MGD. However, some of the wells are not being used to meet the daily water demands due to their poor water quality and the cost of the water treatment. Only, three groundwater supply wells are used to meet water system demands. The wells contain iron, Mn, and hydrogen sulfide. Up until 2005, the City operated a facility to remove hydrogen sulfide using pH adjustment and air stripping, and added a polyphosphate chemical to sequester iron and Mn entering the distribution system. In response to customer complaints regarding the staining of dishwashers and laundry resulting

©2015 Water Research Foundation. ALL RIGHTS RESERVED. from limited effectiveness of sequestration, Renton constructed a new iron and Mn removal treatment facility in 2005. The 3.6 MGD treatment facility provides air induction, GAC contactors, pre-chlorination, greensand filtration, and final chlorine addition and contacting prior to distribution at a single POE. Prior to constructing the new treatment facility, iron and Mn at the POE averaged 0.48 mg/L and 0.60 mg/L, respectively. After the new treatment facility was placed in operation, these levels were reduced to 0.009 mg/L and 0.004 mg/L, respectively. Renton’s water system is comprised of 305 miles of pipelines spread over 13 pressure zones. The system has 4.75 MG of storage capacity with an average water age of 3.5 days. The distribution system is predominantly comprised of cement-lined pipe. An average of 0.9 mg/L chlorine residual is maintained in the distribution system. On average, Renton experiences approximately three discolored water episodes per year. Currently, the City does not have a response plan to address these discolored water episodes because they are usually so minor in nature.

United Water, ID

United Water Idaho (UWID) provides water service to the greater Boise, Idaho area. UWID serves a retail population of 245,000 with an average daily production of 38.4 MGD and a maximum daily production of 83 MGD. The water supply is a combination of surface water and groundwater, distributed to the system by 78 POEs. UWID obtains 70% of its raw water from 76 groundwater wells located throughout the Boise area. Many of the wells have high levels of iron, Mn, and ammonia. Polyphosphate is added to fourteen of the wells to sequester and prevent precipitation of iron and Mn entering the distribution system. Of the remaining groundwater wells, three are treated with greensand filtration to remove iron and Mn. The remaining 30% of the source water comes from the Boise River, which is treated at two water treatment plants: the Marden Water Treatment Plant and the Columbia Water Treatment Plant. The distribution system consists of 1,195 miles of pipe located among ten pressure zones. The system is constructed mainly of plastic (PVC or HDPE) and asbestos cement (AC) pipe. The utility strives to maintain an average free chlorine residual between 0.4 and 0.8 mg/L throughout the distribution system. On an average, the utility has experienced 151 discolored water episodes per year under current conditions, of which 45 episodes/year were in Mn-specific zones. The utility established system-wide proactive flushing program to address Mn build-up in the distribution system. Parts of the distribution system that has potential for discolored water episodes are flushed unidirectionally and the rest of the system is flushed conventionally. Entire distribution system is flushed once a year with a target velocity of 5 feet per second. The utility also flushes the part of the distribution system reactively depending up on the occurrence of the discolored water episodes throughout the year.

OBSERVATIONS REGARDING SURVEY RESULTS

Once the survey was completed, the results were used to provide information to the project about the four topic areas selected to evaluate the impacts of legacy Mn. These topic areas are:

 Topic Area 1. Impact of legacy Mn related episodes on customer satisfaction.  Topic Area 2. Relationship between legacy Mn and co-occurring contaminants.  Topic Area 3. How utilities can response to release of legacy Mn.

The utility survey illustrated a range of ways legacy Mn can impact utilities and a range of actions that utilities take in response to Mn episodes. The survey also indicated the relative lack of both quantitative and qualitative data regarding the impacts of legacy Mn. In order to evaluate the information that utilities were able to provide a matrix was developed indicating what information of interest to the project was available from the survey. Table 3.2 presents this summary. In this table, the four topic areas used to evaluate the impacts of legacy Mn, customer satisfaction, co-occurring contaminants, response to legacy Mn and prevention of legacy Mn, are divided into the desired information about each topic. Next to each item of desired information, the table indicates if the information was available from each utility, using a yes (Y) of no (N). An unclear response is indicated by U. As can be seen from the matrix, much of the information desired by the project was not readily available. In many cases, it was very difficult to discern the impact of legacy Mn. For this reason, follow-up case studies, described in the next chapter were performed with two utilities to provide more detailed and complete information.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 3.2 Summary of information available from utility survey Topic Newport Park United Area Desired Information Arvada Boulder Lacey Moscow Newport News Philly City Renton Water Complaints (#/year) Y Y U Y Y Y Y N N Y Service Disruptions N N Y N N N N Y N N Customer response to Y N U N N N N N N N Mn management Confidence/feedback N N Y N N U N U N N Regulatory issues N N N N N N N Y N N Monitoring/Analytical Y N N U N N Y N N U Lost revenue N N N N N N N N N N Restitution/PR N N U U N N N U Y U 1. Satisfaction Customer Utility labor for N N U U U U N N Y U response Lost customers N N U N N N N N N N Concentrations of N N U N N N N U U N trace metals Correlation of trace N N U N N N N U U N metals with Mn Regulatory issues N N N N N N N U N N Monitoring/control of

Contaminants Contaminants N N U N N N N U U N

2. Co-Occurring 2. Co-Occurring trace metals Monitoring of Mn Y N U U U U Y U U U Manganese loading N N U N N N Y U U N Vulnerable to Mn N N Y N N N N Y N N accumulation/release Pipe materials of N N N N N N N Y N N vulnerable areas Actions to control Mn Y N Y Y U U Y Y N U build-up in the system Monitoring/control of Y N U U U U Y U U U Mn Equipment fouling and N 3. Response to Legacy Mn Mn Legacy to 3. Response N N U N N N U N N replacement (Continued)

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 3.2 (Continued) Topic Newport Park United Area Desired Information Arvada Boulder Lacey Moscow Newport News Philly City Renton Water Effectiveness of N N U N N N U U N N techniques Frequency or percentage of system N N Y U N N U Y N U affected per year % of system flushed Y N Y N N N N Y N U for preventive reasons % of system flushed Y N N N N N N N N U reactively Utility labor N N U N N N N U N N

4.Prevention of LegacyMn Direct costs N N U N N N N U N N Water used N N U N N N N U N N Key: Y = information available, N = information not available, U = unclear

OBJECTIVE OF CASE STUDIES

The utility survey provided a good deal of insight into how utilities respond to legacy Mn episodes as well as types of information they typically collect (or do not collect) about Mn episodes. Yet, as discussed in the previous chapter, much of the information desired by the project to quantify the impacts associate with legacy Mn was not available. A second problem, which became clear in additional discussions with utilities, was how to separate the impacts of legacy Mn from other factors. This is particularly true in the case of relatively minor colored water episodes, which were limited to a small part of the distribution system. For example, a utility receives and responds to a colored water complaint but is unable to verify the problem. Did a problem occur? If so, was it Mn related? More importantly, for relatively minor colored water episodes, would the utility behave any differently if Mn were present or not present in its system? In order to gain insight into these types of questions and to obtain more information about the quantitative and qualitative impacts of legacy Mn two detailed case studies were performed. These case studies permitted the project team to have a direct interaction with the utilities, and permitted a more detailed discussion of utility experiences with legacy Mn. The case study utilities were selected for interview because the survey indicated they had a good deal of quantitative information about the impacts of legacy Mn available. This was because the utilities had to deal with colored water episodes in the past, which were tied to either legacy Mn or pass- through Mn4. Table 4.1 lists the two utilities selected for case study.

Table 4.1 Utilities selected for case study Utility Reason for Selection Information related to two major and unexpected colored water episodes which can be related to legacy Mn accumulated in specific parts of the Park City distribution system supplied by Mn containing source waters. Examples of release of co-occurring metal associated with legacy Mn release. Five wells containing iron and Mn supplying system. Historical information on changes in treatment, evidence of Mn accumulation in specific portions of Lacey the distribution system. Evaluation of effectiveness and cost of UDF in removing legacy in distribution system

4 A pass-through Mn event is caused by the inability of the treatment process to control Mn, resulting in a colored water episode in the distribution system. In other words, the colored water event is not caused by the release of legacy Mn in the distribution system but rather the pass-through of Mn by the treatment process. From the customer’s perspective, this distinction is immaterial; the customer only knows the water is discolored. But from the utility perspective the distinction is important in formulating a response to the colored water episode.

In preparation for completing the case study a detailed ‘utility survey follow-up tool’ was developed. The tool was developed to provide specific questions to guide the face-to-face discussion with the two selected for the case studies. The ‘tool’ was broken into the four topic areas discussed in Chapter 3.

Each of the four topic areas were subdivided into qualitative (non-cost) and quantitative (cost) impacts related to each topic area. Table 4.2 summarizes the type of information requested from case study utilities to assist in the evaluation of each topic area. On-site interviews were held with each utility using the ‘utility data follow-up tool’ as a guide for the interview. A copy of the complete utility data follow-up tool is included in Appendix C.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 4.2 Summary of information requested from case study utilities Topic Area Impact Type Information Needed to Evaluate Impact  Customer complaints related to Mn/colored water.  Service disruptions related to Mn/colored water. Qualitative  Customer feedback/impacts to customer confidence. 1. Customer  Labor effort for complaint response. satisfaction  Monitoring analytical costs for complaint response. Quantitative  Other costs for complaint response.  Customer restitution and public relations efforts.  Lost customers or revenue.  Regulatory – other water quality issues. Qualitative 2. Co-occurring  Regulatory – metals release. water quality issues  Labor effort for monitoring other metals. Quantitative  Monitoring/analytical costs for other metals.  Areas of distribution system vulnerable to Mn accumulation/release. Qualitative  Pipe materials of vulnerable areas.  Actions to respond to Mn release. 3. Response to Mn  Labor effort for reactive distribution system accumulation/release cleaning and monitoring.  Monitoring/analytical costs for reactive distribution Quantitative system cleaning.  Equipment fouling, cleaning and replacement.  Other impacts incurring cost.  Actions to control Mn accumulation. Qualitative  Extent/frequency of action.  Effectiveness of action.  Labor for proactive distribution system cleaning and monitoring. 4. Prevention of Mn accumulation/release  Other direct costs for proactive distribution system cleaning and monitoring. Quantitative  Labor effort for routine distribution system monitoring.  Monitoring/analytical costs.  Other costs.

The case studies are presented in the next section of this report. For the sake of consistency, and to promote a direct comparison between the utilities, the findings for the two case studies are presented using this format:

 Case Study Introduction  Topic Area 1 – Customer Satisfaction - Documentation of dissatisfaction - Action taken to restore satisfaction - Effectiveness of actions to restore satisfaction - Cost Impacts  Topic Area 2 – Co-Occurring Contaminants - Mn–related inorganics accumulation - Regulatory compliance issues - Cost Impacts  Topic Area 3 – Response to Mn Accumulation/Release - Trends in Mn Occurrence - Utility response measures - Equipment fouling - Cost impacts  Topic Area 4 – Prevention of Mn Accumulation/Release - Indicators of accumulation or release - Prevention methods - Costs impacts  Summary of Cost Impacts for all Topic Areas

PARK CITY CASE STUDY

Introduction

The information for the Park City case study was obtained from various sources, including responses to the project utility questionnaire, site visit and interview notes (Feb 2011), case study information and analytical data from participation in WRF #3118 (Friedman et al., 2010), information on system conditions, O&M practices and observations, distribution system water quality from recent consultant investigations and reports, and responses to further Project Team questions. Park City was selected for a case study because it had experienced on-going challenges related to Mn accumulation and associated periodic destabilization/ release episodes, has observed significant levels of regulated trace metal contaminants to co-occur with Mn in pipe and water samples, and regularly performs distribution system monitoring and pipe cleaning practices to control occurrence of legacy Mn and co-associated contaminants. It is important to note that legacy iron typically exists along with Mn in accumulated deposits of affected portions of the utility’s distribution system. This is evidenced by presence of both iron and Mn in bulk and flush water samples at ratios that generally correlate to those in nearby finished water supplies. Note that the piping in the Park City distribution system is predominantly asbestos cement, cement-lined, and plastic. These are generally considered “non- corroding” pipes and do not contribute iron and Mn in deposits; therefore, iron and Mn

©2015 Water Research Foundation. ALL RIGHTS RESERVED. occurrence is primarily due to loading from supply sources (primarily tunnel water). Park City can differentiate between these metals in water samples using field analytical equipment. However, since both of these metals are typically present and contribute to discoloration, the utility does not distinguish between them with respect to recordkeeping of customer complaints. In December 2007 and again in November 2010, Park City experienced discrete water quality “excursion” episodes in a specific zone of its system. These episodes were similar and characterized by relatively extreme discoloration throughout the affected zone, along with persistent elevated levels of several metals including Mn. These episodes were eventually attributed to destabilization of legacy deposits because of water supply changes and associated chemistry shifts. Given that Mn accumulation/release was determined to have played a critical role in the excursion episodes, the elevated Mn levels were of direct concern to customers (in addition to other metals), and Mn was amongst the last parameters to be restored to background levels during response activities (as discussed later), it is considered appropriate to include the various impacts of these two episodes in this assessment.

Topic Area 1 – Customer Satisfaction

Documentation of Dissatisfaction

Perceived. As noted previously, the utility has experienced two major excursion episodes in a specific zone of its system. In each case, the discoloration triggered numerous customer complaints. Water appearance descriptions included yellow, red, and dark brown (coffee) colored water. In 2007, the excursion episode lasted roughly 10 days before water quality conditions were restored and complaint calls discontinued. In 2010, the episode lasted roughly 23 days before water quality conditions were restored. To address growing customer concerns when the repeat episode occurred in 2010, Park City implemented an extensive public information and relations campaign described in more detail below. These excursion episodes, along with the associated monitoring data showing elevated metals levels in select samples, led concerned residents to become very vocal to the utility about taking more aggressive measures to mitigate contaminant accumulation and release, not specific to but inclusive of Mn. Their actions have included circulating petitions for signatures and attending public meetings to express frustration and request more action. Public pressure has resulted in regular media exposure and updates on utility measures and plans to address water quality issues. Park City reported its perception is that consumer confidence has been impaired over the past few years specifically because of the colored water issues. Specifically, residents have expressed concern over whether the water is safe to drink. This concern is not limited to occurrence of regulated trace metals, but also includes concern over health impacts from exposure to elevated levels of Mn. During the excursion episodes, the utility also received complaint calls from area businesses and tourist resorts. Some businesses complained that the water quality issues and advisories had a detrimental impact on their business. Measured. Park City reported that it receives an average of 20 water quality-based customer complaints per year on a system-wide basis, based on recordkeeping within the past few years and excluding the multitude of complaints associated with the excursion episodes in 2007 and 2010. Based on 5,100 total system connections, this equates to about one complaint per 255 connections per year.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Water quality complaints are inclusive of discoloration and taste and odor concerns, as the utility does not differentiate these types of complaints in its records. The utility does not receive complaints relating to gradual staining, spotting, or related “pass-through” Mn impacts. With respect to the two excursion episodes, the total number of complaints received during each was not tracked. However, based on the size of the affected area and the time of year, the utility estimated that somewhere between 500 to 1,500 customers (mostly residents and visitors) were likely affected to some degree. During the 2010 excursion episode, customer complaints were received from approximately 60 unique services in the affected zone (out of 401 total connections in this zone). Complaints were also received from several businesses and resorts in the affected area.

Actions Taken to Restore Satisfaction

Response to Customer Complaints – Park City follows up on all customer complaints of colored water by visiting the particular residence or location, checking the meter to see if the problem originates from the individual service or from within the distribution system, and, if warranted, performing spot flushing of the water mains in the vicinity of the residence to displace colored water and restore water quality. Depending on the nature of the complaint and observations made in the field, the utility may also perform on-site/at the meter monitoring of chlorine residual, iron, Mn, and turbidity, and/or collect a sample for off-site microbial analysis. Restitution. Park City has not made payment or restitution for any damages, whether perceived or real, due to legacy Mn or co-occurring contaminants. Following the 2010 excursion episode, several customers requested and were denied a credit of their entire water bill and/or replacement of their point-of-use filter devices. Service Interruption Response. During the 2010 excursion episode, Park City notified all customers in the affected zone to temporarily avoid use of tap water for consumption or bathing until metals levels could be reduced and verified. However, water supply to the affected zone was not shut off. During this “service disruption”, the utility set up a centralized location with free bottled water and made public shower facilities available to residents. The utility reports that the bottled water resources were heavily used while the showers were not. Public Relations. During the excursion episodes in 2007 and 2010, Park City implemented a public relations campaign. In both episodes, the utility participated in interviews and notifications for TV and radio broadcasts and provided information for print in the local newspaper. During the 2010 episode, a more extensive campaign was implemented to keep residents and visitors informed and updated. Park City followed guidelines from the Incident Command System with respect to coordination and public communication. Measures taken included providing public advisory notices in local media (print, television, and radio), maintaining a phone hotline, maintaining a website with daily updates on activities and water quality results, and distributing door hanger flyers to residents, businesses, and hotel front desks (to inform visitors) within the affected area. Public Meetings. Park City continues to hold held regular public meetings to gather input from the community. Since 2010, the utility has typically held approximately two public meetings and/or radio interviews per year specific to water quality issues. Continued public meetings are anticipated to discuss additional distribution system water quality study results and large water quality projects directly related to treating mine tunnel water for drinking water and stream discharge purposes.

The history of customer complaint records is too limited to quantify whether routine unidirectional flushing has had an impact. However, Park City reports that application of this practice has been viewed as a positive and proactive measure by customers when they understand the need for the practice. The only customer complaints have been relative to concerns over water conservation when operators are flushing. Park City plans to develop more public awareness information, so that residents understand the balance that must be in place between maintaining the health of the water quality in the distribution system and water conservation. Park City reports that residents and visitors of this affluent area expect a very high level- of-service. Public pressure from residents of the zone affected by the excursion episodes has continued to build since the repeat episode occurred in 2010, as indicated by signed petitions and resident presence and comments given at public meetings. This pressure is primarily related to the desire to permanently mitigate the acute water quality episodes associated with metals/particulate release (as opposed to sporadic color complaints). Therefore, although unidirectional flushing applied during and since the first excursion episode provided short-term restoration of water quality, it was ineffective at restoring customer satisfaction on a long-term basis because it did not fully eliminate the problem. With respect to customer notification, Park City reports that personal/phone contact and delivery of door hangers were the most effective methods during the 2010 episode.

Cost Impact Summary: Topic Area 1 - Customer Satisfaction

Response to Customer Complaints. Park City reportedly spends an average of six total person-hours per complaint. Restitution. Park City has not paid direct costs for restitution. Service Interruption Response. The estimated cost of bottled water provisions during the 2010 episode response was $15,000. The utility reported that the excursion episodes resulted in reduced water sales revenue because of customers in the affected zone curtailing water usage during the episodes. Water use was down by an average of 2,000 gallons per week per service. Resulting impacts to sales revenue were estimated at $4,500 in 2007 and $7,500 in 2010. Public Relations. Over 200 hours were spent per excursion episode on various public relations/ notification activities, including distributing door hangers, maintaining the website, radio interviews and handling inquiries. Public Meetings. Since 2010, Park City has typically held two public meetings and/or radio interviews per year specific to water quality issues. Staff time to prepare for and conduct these meetings is not tracked.

Topic Area 2 – Co-Occurring Contaminants

Manganese-Related Inorganics Accumulation

Contaminants. Park City has monitored for a broad range of contaminants in distribution system water samples since the first excursion episode occurred in 2007. This includes routine surveillance monitoring at several fixed locations as well as monitoring performed during excursion episodes and flushing activities. The routine system monitoring program was

©2015 Water Research Foundation. ALL RIGHTS RESERVED. developed in coordination with the state regulatory agency and is intended to provide surveillance of contaminant behavior beyond system points-of-entry (POE). Under this plan, Park City performs quarterly sampling at eight locations. All analyses are performed by a certified commercial laboratory. The first several days of monitoring during each excursion episode included all regulated volatile organic, synthetic organic, and inorganic contaminants, secondary and unregulated inorganic and physical parameters, and microbial indicators. The list of parameters was eventually refined to focus on inorganic and physical parameters. Organic contaminants (aside from disinfection byproducts) were consistently demonstrated to be non-detect. Similarly, coliform and E. coli were not detected during either of the excursion monitoring episodes. Distribution system monitoring performed during excursion episodes has identified the accumulation of several metals on system pipe deposits, most notably iron, Mn, arsenic (As), lead (Pb), thallium (Tl), and mercury (Hg). With the exception of mercury (which has been non- detect), each of these metals are present at measureable but MCL-compliant levels in nearby POEs. Findings/correlations. During excursion episodes, the aforementioned metals were observed in bulk water samples at levels ranging from their POE concentration (background) to one or more orders-of-magnitude greater than background. In some cases, the observed levels exceeded the corresponding water quality standard for the contaminant. Between the two episodes, maximum reported results for specific metals are as follows: iron 4.7 mg/L, Mn 2.2 mg/L, arsenic 0.09 mg/L, lead 0.06 mg/L, thallium 0.32 mg/L, and mercury 0.02 mg/L. Trace metals accumulation on pipe surfaces was in particulate or solids-associated form involving co-precipitates with iron and Mn solids (WaterWorks, 2011; Friedman et al, 2010). Emerging research shows that iron and Mn oxide solids are highly effective adsorbents of dissolved trace metals in drinking water systems. In particular, Mn solids have a high affinity to adsorb and concentrate dissolved cationic metals like lead and thallium (Friedman et al, 2010) or anionic oxides like arsenate. Thallium co-precipitation and release with Mn is supported by correlated data from water samples collected during excursion responses (see Figure 4.1). In 2008, Park City extracted the pipe specimen shown in Figure 4.2 from the excursion- affected zone and provided it to the WRF 3118 research investigation for compositional analysis of the deposit layer. Accumulation of Mn is reflected by the black coating seen in the sample. The concentrations of Mn and trace metals found in the deposit layer (as reported in the table) were generally above the respective 90th percentiles of the collective dataset for the research study in which 46 pipe samples were obtained from 20 different utilities.

0.10 0.06 0.05 0.08 (mg/L)

(mg/L) 0.04 0.06 0.03 0.04 Thallium 0.02 Manganese 0.02 0.01

0.00 0.00 Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov Nov ‐ ‐ ‐ ‐ ‐ ‐ 7 8 9 7 8 9 10 ‐ 11 ‐ 12 ‐ 13 ‐ 14 ‐ 15 ‐ 16 ‐ 17 ‐ 18 ‐ 10 ‐ 11 ‐ 12 ‐ 13 ‐ 14 ‐ 15 ‐ 16 ‐ 17 ‐ 18 ‐ Dissolved Particulate Dissolved Particulate Source: Courtesy of Confluence Engineering Group

Figure 4.1 Zone-average Mn and thallium levels in daily water sampling during the 2010 excursion episode

Source: Adapted from Friedman et al. 2010

Figure 4.2 Pipe sample from affected zone and its deposit elemental composition

Given the solids-associated form of these contaminants, unidirectional flushing was useful to remove destabilized and suspended material. However, flushing (at 3 fps) was neither fully effective at cleaning the pipe surfaces nor at restoring bulk water quality conditions. As shown in Figure 4.1, sample speciation during the 2010 excursion episode revealed that release included a chemical dissolution component as well, with initial Mn and thallium levels being mostly in a soluble form. As a result, elevated levels of certain metals persisted even after the color cleared up following flushing. Restoration of the previous water supply pattern was also needed to re-establish stable water chemistry. The number of days needed to re-establish equilibrium and reduce contaminant levels down to background levels in 2010 was contaminant- specific, in the order: iron, arsenic > Mn, thallium > mercury.

Regulatory Compliance Issues

MCL/SMCL. During the recent excursion episodes, metals were observed in some water samples at levels in excess of their respective primary or secondary MCLs (see previous discussion). Given that the current inorganics regulatory framework for MCL compliance is based on POE monitoring and results, these episodes did not constitute a regulatory violation. Nonetheless, given the potential for public concern, Park City reported the findings to the state

©2015 Water Research Foundation. ALL RIGHTS RESERVED. regulatory agency and coordinated directly with regulators on a monitoring, public notification, and response plan. The utility performed daily monitoring with overnight laboratory turnaround to track water quality changes and determine when levels dropped below MCLs/sMCLs and when they reached background levels. The utility provided on-going updates of water quality results to customers. Only once all metals reached background levels were customers told that water quality had been restored to normal and advisories lifted since 2010. Other. Park City has not experienced any other regulatory challenges associated with accumulation of Mn, iron, or co-occurring trace metals. Park City reported an improvement in chlorine residual stability since routine flushing activities were initiated in 2007. This may be due to the removal of Mn solids and other chlorine- exerting solids.

Cost Impacts Summary: Topic Area 2 - Co-Occurring Contaminants

Labor Effort. Park City performs routine surveillance monitoring of inorganic contaminants within its distribution system, based on a plan developed with the state regulatory agency. Under this plan, the utility performs quarterly sampling at eight locations. On average, each round requires 6 hours of utility labor effort to collect and ship samples. Analytical. The parameters monitored during each round of routine surveillance monitoring include: antimony, arsenic, barium, beryllium, calcium, cadmium, chromium, copper, iron, lead, mercury, magnesium, Mn, nickel, selenium, sodium, thallium, zinc, hardness, cyanide, fluoride, nitrate, sulfate, and total suspended solids. Analyses are performed by a certified commercial laboratory. The analytical cost is approximately $2,600 per quarter. Contractor. Park City performs monitoring activities in-house and thus does not incur contractor-related costs, aside from contract laboratory expenses discussed above.

Topic Area 3 – Response to Manganese Accumulation/Release

Trends in Manganese Occurrence

Manganese accumulation occurs to some degree throughout the utility distribution system, as reflected by Mn occurrence in flush water samples. However, there is a strong spatial component to the extent of accumulation. Mn accumulation is most prevalent and problematic in two adjacent zones within the system. Pipe samples in these areas are often described as containing a black film or slime layer (see Figure 4.3). Based on limited opportunities to observe pipe interior conditions in other parts of the system, the pipes are generally smooth and lack significant film or deposit accumulation.

Source: Courtesy of Park City

Figure 4.3 Black film/slime layer scraped from 0.5 to 2.5 inches of a10-inch ductile iron pipe sample obtained from Park City

The piping within the Park City distribution system is predominantly asbestos cement, cement-lined, and plastic. These pipe types are generally considered “non-corrosive” and do not contribute to Mn or iron in deposits. Therefore, Mn and iron occurrence in the distribution system is attributed to historical and on-going loading from various sources of supply (with subsequent oxidation and deposition on pipe surfaces). The two zones most heavily influenced by Mn build-up have historically been served by mine tunnel sources, Mine Shaft 1 (MS1) and Mine Shaft 2 (MS2), each of which contain naturally-occurring Mn. Raw water from the tunnel that directly serves the zone affected by excursion episodes (MS1) contains about 0.04 mg/L Mn, while raw water from the second tunnel that directly serves the adjacent zone (MS2) contains about 0.01 mg/L Mn. These sources have been in use since 1981 and 1971, respectively. In 1993, a WTP was installed to treat MS1 and consisted of a pressurized media filtration system to remove particulate arsenic. In 2003, the WTP was expanded and upgraded with ferric chloride coagulation for additional arsenic removal. The filter media was also replaced with a catalytic oxidizing media for Mn removal. The process consistently removes Mn to  0.005 mg/L. Although current Mn loading due to treatment breakthrough is relatively low from this source, historical Mn loading likely contributed to legacy Mn accumulation in the affected zone. MS2 is treated with chlorine only; therefore, Mn in the raw water is carried directly into the distribution system where reaction with chlorine residual results in its oxidation and potential for deposition.

Utility Response Measures

System Monitoring. In addition to performing routine quarterly monitoring within its distribution system, Park City performs sampling/monitoring in response to discoloration episodes, customer complaints, and before and after flushing activities. The monitoring locations and duration depends on the nature of the issue. During the 2010 excursion episode, the utility performed daily monitoring within the affected zone at seven specific residences (hose bibs) and four specific hydrants.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Monitoring includes both on-site field tests and samples for off-site analyses by a certified commercial laboratory. While the parameters assessed vary depending on the nature of the issue, location, and other factors, the following parameters are often tested: pH, temperature, alkalinity, conductivity, hardness, oxidation-reduction potential (ORP), turbidity, color, chlorine residual, metals, anions, HPC, iron bacteria, and sulfur-reducing bacteria. Reactive Flushing. Park City developed a UDF program in late 2007 in response to the first excursion episode. Flushing loops were developed for the affected zone, and subsequently, for the entire water system. The loops were categorized into discrete areas/zones to allow focused unidirectional flushing efforts in response to localized discoloration issues or complaints. Since 2007, Park City has used UDF to mitigate discoloration episodes. Prior to this, the utility performed conventional spot flushing as needed to address discoloration complaints. Flushing is achieved using a hose monster and pitot gauge for velocity measurement. Historically, a flushing velocity of 3 feet per second (fps) was applied due to concern that the use of greater velocities could damage pipes and cause main breaks, particularly in older sections of asbestos-cement pipe. In some areas, there are pressure limitations to achieving higher velocities. Velocities closer to 6 fps are currently targeted. In response to water quality upsets, the utility flushes at least two pipe volumes and until discharge turbidity (measured on-site) reaches background levels or is <2 NTU. For extremely discolored flush samples, the utility also collects samples for laboratory analysis of metals and at times bacteria. In response to individual or isolated customer complaints, Park City performs localized UDF as described previously. In response to episodes involving more numerous and widespread complaints, the utility performs area- or zone-wide UDF. If needed to restore water quality, the utility will flush the area or zone multiple times as warranted based on data. For example, during the 2007 and 2010 excursion episodes, the utility performed flushing throughout the affected zone for roughly 7 and 21 consecutive days, respectively, in order to achieve targeted water quality conditions. Table 4.3 summarizes labor impacts/costs associated with distribution system flushing. Separate columns are provided for reactive flushing in the excursion-affected zone (for each of the 2007 and 2010 episodes) and routine annual system-wide preventative flushing. Of note is that reactive flushing during the excursion episodes required repeat flushing of the same area to restore water quality, i.e., greater than 100% turnover. As a result, normalized labor effort/cost for reactive flushing exceeds that of annual preventative flushing, on the basis of person-hours or $ per total pipe-miles per “episode”. Given the observed limitations of UDF cleaning performance on the types of Mn films seen in portions of its distribution system, Park City is currently investigating the implementation of other more aggressive main cleaning techniques such as foam swabbing and ice pigging to achieve removal of legacy Mn and co-occurring contaminants.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 4.3 Summary of reactive and preventative flushing impacts 2007 Episode 2010 Episode Routine Parameter Unit Response Response Preventative Pipe-Miles Flushed pipe-mile 94 281 120 Number of Days of days 7 21 NR3 Flushing pipe- Average Cleaning Rate 3.4 3.4 3.4 mile/day/crew1 Total Pipe-Miles in Area pipe-mile total 11.4 11.4 120 % of applicable 825% 2,465% 100% Area Turnover area per episode per episode per year Total Labor for Field Crew person-hours 448 1344 560 person- hours/pipe-mile 4.8 4.8 4.7 Normalized Labor for Field flushed Crew person- 39.3 118 4.7 hours/pipe-mile per episode per episode per year total Estimated Cost of Field $ $18,600 $55,800 $23,200 Crew Labor2 $/pipe-mile $200 $200 $195 Normalized Cost of Field flushed Crew Labor2 $1,630 $4,900 $195 $/pipe-mile total per episode per episode per year Based on four 2-person crews working 8-hr shifts per day Based on burdened labor rate of $41.51/hour NR = not reported

Equipment Fouling

Park City has not knowingly experienced fouling of distribution system equipment or components due to Mn presence.

Cost Impacts Summary: Topic Area 3 - Response to Manganese Accumulation/Release

Labor Effort. The labor time/cost associated with performing monitoring and local flushing in response to individual customer complaints is factored into the average figure of six total person-hours per complaint. The average labor effort associated with monitoring at fixed locations during 2007 and 2010 excursion episodes is four person-hours per day. The absolute labor time/cost associated with monitoring and flushing in response to more widespread episodes is variable and depends primarily on the size of the affected area and duration of the episode, as illustrated in Table 4.1.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Analytical. The commercial laboratory analytical cost associated with complaint response monitoring is estimated at $4,000 per year ($200 per complaint, or $0.78 per service connection on a system-wide basis). In 2007, the commercial laboratory analytical cost associated with one week of distribution system monitoring in response to the excursion episode was estimated at $40,000. In 2010, the commercial laboratory analytical cost associated with three weeks of distribution system monitoring in response to the excursion episode was estimated at $200,000. Contractor. Park City performs flushing and monitoring activities in-house and thus does not incur contractor-related costs for these tasks, aside from contract laboratory expenses as previously discussed. In response to the 2010 excursion episode, the utility hired a consultant to assist with identification of the cause of the episode and the development of recommendations to prevent future episodes. The direct cost of this investigation was about $25,000. Other. Additional costs incurred due to Mn response activities include equipment and software acquisition to perform UDF. This is further discussed as part of preventative mains cleaning in the following section.

Topic Area 4 – Prevention of Manganese Accumulation/Release

Triggers or Indications of Accumulation or Release

Discoloration episodes are typically associated with release of accumulated precipitates and/or dispersion of black slime layers. The degree of discoloration depends on the amount of material entrained. Release episodes occur due to physical/hydraulic mobilization resulting from flow reversals and velocity changes, as well as chemical destabilization and solubilization resulting from water chemistry shifts. The recent excursion episodes were attributed to legacy deposit destabilization due to seasonal switching between dissimilar sources. The degree to which soluble release episodes involving Mn and/or co-associated trace metals occur is not well understood since response monitoring is typically triggered based on color (particle release) as an indicator of an upset.

Prevention Methods

Treatment. Source water and treatment impacts on finished water Mn were previously discussed. Treatment for Mn co-removal has been applied for MS1 since 2003. MS2 is not treated beyond disinfection with chlorine and currently represents the largest contributor of Mn loading to the system. Park City is in the planning phases of a project to treat MS2, with emphasis on removal of iron, Mn, arsenic, lead, and antimony. Park City maintains a free chlorine residual throughout its distribution system for secondary disinfection purposes, with a target range of 0.3–1.0 mg/L as Cl2. This helps maintain ORP above 600 mV within the distribution system and promotes oxidation of soluble Mn to a particulate form capable of settling out. Of note is that the utility applies sodium bisulfate solution at the Spiro WTP to reduce filter effluent chlorine residual levels from 3 mg/L down to 1 mg/L prior to distribution. There have reportedly been occasional process control challenges with this feed system that have resulted in temporary loss of residual and possibly local ORP impacts. It is not clear if these occurrences have contributed to release or dissolution of legacy Mn solids and/or adsorbed contaminants.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Preventative Flushing. Park City developed and implemented a unidirectional flushing (UDF) program in response to the first excursion episode. (Flushing activities are illustrated in Figure 4.4.) Flushing loops were developed for the affected zone, and subsequently, for the entire water system. The utility performs routine UDF of its entire distribution system once to twice per year during the low demand/low tourism period. The purpose of this effort is to control solids and metals buildup, including but not exclusive to Mn, with the goal to prevent further excursion episodes.

Source: Courtesy of Park City

Figure 4.4 Park City field crew conducting unidirectional flushing of water system

Effectiveness of Measures. During initial flushing efforts in 2007, significant amounts of particulate solids and discoloration were reportedly observed during the first pipe volume of each flushing loop. In recent efforts, discharge turbidity/color drop off and background iron and Mn levels are achieved quickly. These findings suggest that the pipe surfaces are maintained relatively clear of loosely settled material. While UDF at 3 fps may have provided some value with regard to reducing the extent of contaminant buildup and limiting the magnitude and/or frequency of discoloration episodes, it did not remove all accumulated material in certain areas. This is evidenced by the recurrence of a major excursion episode in the affected zone in 2010 after repeated UDF in this area since the first episode in 2007. Incomplete removal is likely due to the fact that Mn tends to form more cohesive, hydraulically resistant films on pipe walls that require higher flushing velocities and/or more aggressive cleaning techniques to remove.

Labor Effort. Labor effort/costs associated with sample collection for routine Mn monitoring are part of the overall costs for routine distribution system monitoring provided in Topic Area 3. The labor time/cost for water department field crew to perform system-wide UDF (i.e., 100% turnover per year) is included in Table 4.3. The effort typically requires about 560 person- hours per year, based on flushing done in 2011. With a system inventory of 120 pipe-miles, this equates to an average of 4.7 person-hours per pipe-mile flushed, which is virtually identical to that of response flushing. However, given that preventative flushing is based on 100% turnover (lower than response flushing performed during excursion episodes), the person-hours per total pipe-miles is comparatively lower. Additional time was incurred, but not tracked, during initial planning and loop development; however, these costs are not recurring. Analytical. Commercial laboratory analytical costs associated with routine Mn monitoring are part of the overall costs for routine distribution system monitoring provided in Topic Area 3. Contractor. Park City performs flushing activities in-house and thus does not incur contractor-related costs for that activity. However, the utility is currently investigating more aggressive main cleaning techniques, which may result in future costs for vendor support. These techniques, which are geared to remove resistant Mn coatings, typically involve specialized equipment and techniques and may involve a contractor. Other. At the onset of the UDF program development, Park City incurred additional direct costs in the form of equipment purchases. The utility purchased two trucks, a hose monster for diffusion, a vacuum trailer, and a field laptop.

Summary of Cost Impacts for All Topic Areas

Table 4.4 summarizes Park City cost impacts described in this case study associated with, but not necessarily exclusive to, the accumulation of Mn. As previously discussed, some costs are not tracked and cannot be reliably estimated. Except where otherwise noted, internal costs associated with utility labor are based on Y2012 burdened costs inclusive of fringe benefits ($41.51/hr). As shown in Table 4.4, certain impacts and absolute effort/cost figures have been normalized using spatial and temporal factors. For a given impact, these factors were specific to the zone and timeframe in which the impact data applied or was derived for, e.g., system-wide or excursion area, and annual vs. specific episode.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 4.4 Summary of Park City legacy Mn cost impacts Absolute Impact Normalized Impact Activity and Costs1 and Costs1 Notes/Comments Customer Satisfaction Based on average Customer complaints of 20 per year system- 1 per 255 services trends since 2007. water quality wide per year Not Mn-specific. Labor for addressing 0.024 120 hrs/year = Average 6 hrs per customer water quality hrs/service/year = $5,000/year complaint. complaints $0.98/service/ year Customer requests Restitution related to were received during customer complaints and $0 $0 excursion episodes excursion episodes but denied Associated with Bottled water provision $37.5/service $15,000 (Y2010) Y2010 excursion during excursion episodes (Y2010) episode. Lost revenue due to $11.3/service reduced water sales $4,500 (Y2007) (Y2007) Associated with during release $7,400 (Y2010) $18.5/service excursion episodes. episodes/service (Y2010) disruption Labor effort for public >0.5/service notification (door >200 hrs (Y2010) (Y2010) Associated with 2010 hangers, website, media, >$8,300 (Y2010) >$20.8/service excursion episode. etc.) (Y2010) Co-Occurring Contaminants Labor for routine Quarterly at 8 surveillance monitoring 24 hrs/year = $0.29/service locations within distribution system $1,000/year 6 hr per round (including Mn) Commercial laboratory cost for routine $10,400/year $2.04/service distribution system monitoring (continued)

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 4.4 (Continued) Absolute Impact Normalized Impact Activity and Costs1 and Costs1 Notes/Comments Response to Mn Accumulation/Release Labor for addressing customer water quality See above See above See above complaints Commercial laboratory cost associated with $200/complaint/year $4,000/year monitoring during $0.8/service/year complaint follow-up 39.3 hrs/pipe-mile 448 hrs/episode = total = $1,630/pipe- Labor for flushing in See Table 4.3 for $18,600 (Y2007) mile total (Y2007) response to metals more detailed 1344 hrs/episode = 118 hrs/pipe-mile excursion episodes breakdown $55,800 (Y2010) total = $4,900/pipe- mile total (Y2010) 28 hr/episode = Labor for short-term $1,200/episode distribution system (Y2007) Not scaled Daily at 11 locations monitoring during metals 84 hr/episode = excursion episodes $3,500/episode (Y2010) Commercial laboratory $40,000 (Y2007) cost during metals Not scaled $200,000 (Y2010) excursion episode

Investigational study into One-time cost $25,000 Not scaled excursion episodes (Y2011)

Prevention of Mn Accumulation/Release Labor effort for routine 4.7 hrs/pipe-mile system-wide 560 hrs/year = total/year unidirectional flushing $23,200/year $195/pipe-mile (UDF) program total/year Two trucks: $30,000/ea Hose monster: New equipment for UDF One-time costs $1,000 Not scaled program (Y2007) Vacuum trailer: Field laptop: $1,000 Internal costs associated with utility labor are based on Y2012 burdened labor rate of $41.51/hour

Introduction

The information presented below was obtained from Lacey’s answers to the utility questionnaire, a follow-up interview, responses to further Project Team questions, and historical project reports. Lacey was selected for a case study because in the past, they observed significant Mn (and iron) problems in their distribution system water and still work to prevent legacy Mn from reaching customers’ taps. It is important to note that customer complaints can be caused by Mn or iron in Lacey’s system. The Department indicates that Mn-only problems are usually in the south end of a particular pressure zone (the 337 pressure zone), but most complaints are in areas that are being or have been loaded with both iron and Mn. Their current complaint tracking practices do not distinguish between the two. Lacey serves about 67,175 customers and, in 2008, Lacey estimated they served 31,415 equivalent residential units (ERUs). In that same year, there were 21,255 customer connections to the system. Lacey’s distribution system is about 357 miles long and consists of plastic (PVC or HDPE), concrete/transite (AC), and cement lined ductile iron.

Topic Area 1 – Customer Satisfaction

Documentation of Dissatisfaction

Perceived. The Department indicates that complaints are generally related to particles and colored water caused by release of legacy Mn. The Department attributes these releases to changes in water quality, due to differences in pH of their well waters. Measured. Lacey’s customer complaints have been documented in a database since 1998. There were brown water complaints at this time, but complaints increased in 2002, coinciding with an increase in commercial and residential development in Lacey, implementation of an iron/Mn treatment facility (online in 2001), and an unusually large number of main breaks. During 2002 and 2003, Lacey experienced a peak in problems with Mn presence in the water being served to their customers. During this time, the Department received 443 customer complaints. Of these, 365 were “brown water” complaints. Of those, 75-80 were attributed to problems at an iron/Mn treatment facility at a single source (Well B) that was operated intermittently, resulting in the loading of soluble iron and Mn under reducing conditions when the plant was not operating versus low iron and Mn loading under oxidizing conditions when the plant was operating. Additionally, the Department indicated that there were probably more complaints, which were not documented at this time. Since 2008, Lacey has received eight to twelve brown water calls each year. Half of these (four to six) are likely caused by Mn, according to the Department. For example, in 2009, five of ten brown-water calls were clearly caused by Mn. Of these, four occurred in the 337 pressure zone. Service disruptions have primarily occurred only when flushing crews had to flush through service meter connections if a blow-off was not available. Since this time, blow-offs have been installed to eliminate these disruptions.

Response to Customer Complaints. Currently, water quality complaints are isolated incidents and are addressed by conducting flushing near the customer’s service line until the water is clear. Cost for Response to Customer Complaints. Since 2008, Lacey attributes four to six complaints to Mn and responds by conducting flushing to remove the brown water. Lacey estimates that a two-person flushing crew spends one to three hours conducting this flushing. Assuming utility staff spend sixteen to twenty-four hours conducting flushing to address complaints, the Department estimates a cost of about $600 (salary only) to $900 (salary only) spent on labor to address these complaints each year. Estimate including benefits: approx.: $1,600 to $2,400. Cost for Blow-off Installation. The Department installed blow-offs to prevent service disruptions during flushing. Blow-offs provide more convenient access to crews and can be efficiently and effectively flushed, unlike service lines. Lacey estimates that 100 have been installed to address Mn and iron issues. Based on this experience the unit costs for blow-off installation are:

Materials (valves, pipe, couplers, etc.) $850.00 Labor (3 people for 3 hours – salary only) $336.24 Rock, paving, restoration, etc. $750.00 Supervisor/Managerial Time (2 hours – salary only ) $105.46 Trucks & equipment $300.00 Grand total = $2,341.70 Note: Labor and managerial estimate (with benefits) might be closer to $1,200.

According to this estimate, the Department has spent about $234,170 to install approximately 100 blow-offs, which assist with addressing Mn issues. Cost for Customer Inquiries. The Department estimates that they spend 2 hours per year on the phone answering questions regarding stain removal and other issues associated with Mn release. Staff costs associated for this would be about $74, based on the Department’s estimate of salary (only) costs. Estimate including benefits: approx. $200. Restitution. No restitution has been paid since then. With respect to restitution, the Department is unable to track down the costs because their insurance carrier does not keep records longer than six years and the Department person who handled the claims is no longer available. Customer complaint records indicate that seven callers were referred to the claims person between 2002 and 2003. It is not possible to know if all of these claims were paid. One record indicates that a claim was settled for $1,700. Lacey also indicates that these costs could be due to iron, Mn, and the presence of iron-bacteria. If Lacey paid this amount of restitution for seven complaints, the costs would be $11,900. Public Relations. Lacey sent out two sets of letters to customer regarding the brown water episodes and Lacey’s effort to address these episodes. The Department has relied on public relations to inform customers about the comprehensive unidirectional flushing program carried out by the Department. When the program was initiated, the Department indicates that they used letters, press releases, their website to educate customers, and door hangers in affected areas. They currently rely solely on an email distribution list except for when the central business

©2015 Water Research Foundation. ALL RIGHTS RESERVED. district is scheduled for night flushing. In this case, someone from the utility informs the business personally. Lacey also posts signs at street entries prior to flushing and during flushing. Lacey estimates that the cost of sending the letters describing the brown water episodes was $18,000. During the initial education program for flushing, the Department’s records indicate that they spent $400 on postage to the area of the distribution system most associated with Mn problems. Lacey estimates that this involved mailing letters to 2,500 customers.

Effectiveness of Actions

The Department perceives their unidirectional flushing program as being effective with regard to legacy Mn/iron. There have been significantly fewer complaints since flushing was implemented. Complaints are now more likely to be about black specks or tea-colored water instead of black water. However, improvements in treatment practices occurred concurrently, which helped to reduce Mn/iron loading to the distribution system. A detailed discussion of the effectiveness of UDF for removal of legacy Mn is provided in later in this section.

Topic Area 2 – Co-Occurring Contaminants

Manganese-Related Inorganics Accumulation

Contaminants. Lacey has not specifically monitored for inorganic contaminants (excepting iron) co-occurring with Mn present in distribution system water served to customers. However, during flushing evaluations and reservoir cleaning, Lacey has conducted limited evaluations of the nature of particles present as described below. Findings/Correlations. As shown in Table 4.5, heterotrophic bacteria, iron bacteria, and sulfur bacteria co-accumulate with iron and Mn pipe scales on PVC pipe. Solids captured during flushing ranged from 1.5–8.7 percent volatile, suggesting that approximately 91-98% of the captured material was inorganic. The material removed from the PVC pipe was fairly uniform with percent volatile solids ranging from 7.2 to 8.6%, regardless of net size or flushing velocity. The material captured from the AC pipe contained significantly less organic material, ranging from 1.5 to 2.3% organics.

Table 4.5 Bulk water quality conditions during PVC pipe flushing trial at 7 fps Elapsed Colifor Iron Sulfur. Total Total Time HPC m per bacteria bacteria Turbidity* Fe Mn Sample m:s CFU/mL 100 mL per L per L NTU mg/L mg/L Initial 0:0 30,000 <1 7.0 x 106 3.2 x 105 17 3.51 0.18 1 0:30 7,900 <1 7.7 x 106 3.2 x 105 38 16.4 0.31 2 1:00 1,400 <1 2.4 x 106 6.4 x 105 7.75 1.7 0.04 3 1:30 700 <1 8.6 x 105 1.6 x 103 1.23 1.32 0.01 4 2:00 560 <1 2.5 x 105 1.1 x 104 0.76 0.14 0.01 Final 17:00 100 <1 3.5 x 104 6.4 x 103 0.53 0.07 <0.01 * Field measurement Velocity 7 fps

Lacey also collected a sample of material removed during cleaning of Reservoir A in April 2003 to evaluate whether there was co-occurrence of arsenic. Table 4.6 presents the results

©2015 Water Research Foundation. ALL RIGHTS RESERVED. of the analysis. Lacey indicates that an increased bacterial presence has coincided with their problems with Mn (and iron) and heterotrophic bacteria counts have decreased due to flushing activities as well as enhanced disinfection practices.

Table 4.6 Results of Reservoir A biofilm analysis Measured Parameter (mg/L) Manganese 7.94 Iron 13.2 Arsenic 0.013 HPC 13,000

Regulatory Compliance Issues

MCLs/SMCLs. Although Lacey’s sources complied with all SDWA regulations for primary contaminants, the city system would occasionally get coliform-positive samples and non-acute violations in its undisinfected system. The frequency of coliform-positive samples started increasing in 2002, and in 2004, the city incurred three non-acute coliform violations, all within the 337 zone. These violations resulted in the city chlorinating part of the system on a temporary basis in 2004, and when the third violation occurred after temporary chlorination ceased, the city started chlorinating the entire water system beginning in 2005. Although the city’s UDF program started in 2004, prior to the occurrence of the three non-acute violations, positive coliform results did not occur at the same time as brown water episodes or during flushing activities. Table 4.7 presents iron and Mn levels associated with each source associated with the presence of legacy Mn in Lacey’s distribution system.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 4.7 Summary of iron and Mn at the point of entry for (selected) Lacey’s source waters Source (Year Lacey brought source Treatment online) (Year treatment began) Manganese (mg/L) Iron (mg/L) A None 0.01 <0.1–0.1 (1993) Treatment 1: chlorine, pyrolusite media filtration, ascorbate (dechlorination) Prior to Treatment: Prior to Treatment: B (2002) 0.45 0.45 (1976) Treatment 2: Treatment 1: 0.019 Treatment 1: 0.026 permanganate, chlorine, Treatment 2: 0.005 Treatment 2: 0.007 pyrolusite media filtration (2003) Prior to Prior to implementing C implementing Chlorination (2004) Chlorination: 0.05 (1981) Chlorination: 0.17 Chlorination: 0.04 Chlorination: 0.10 Treatment 1: blending in the adjacent 4MG reservoir to achieve a target of <0.01 Mn and <0.01 sulfide. Blending stopped after system-wide chlorination due to discoloration problems. Treatment 2: aeration, GAC Prior to Treatment: Prior to Treatment: filtration, chlorine, Mn D 0.03 0.14 greensand filtration, (1995) Treatment 2: 0.002 Treatment 2: 0.01 breakpoint chlorination in Treatment 3: 0.016 Treatment 3: 0.08 contact basin, and chlorine boosted as needed before delivery (2008) Treatment 3: chlorination, Mn greensand filtration, breakpoint chlorination in contact basin, and chlorine boosted as needed before delivery (2009) E Prior to Prior to implementing (1989 and use implementing Chlorination (2005) Chlorination: 0.05 discontinued in Chlorination: 0.1 Chlorination: 0.04 2007) Chlorination: 0.03

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Residual Maintenance. The City implemented temporary disinfection in 2004, and system-wide permanent disinfection in 2005. Since the distribution system was undisinfected during the brown water episodes, it is not possible to assess potential impacts of legacy Mn on residual maintenance. Prior to implementing disinfection, the City embarked on a system-wide unidirectional flushing program to remove as much accumulated material as possible. The effectiveness of this program is described below. Given the amount of material removed, it is likely that the program contributed significantly to the successful conversion to full-scale permanent disinfection and on-going disinfectant residual maintenance.

Cost Impacts Summary: Topic Area 2 - Co-Occurring Contaminants

Lacey did not experience direct cost impacts associated with regulatory compliance and legacy Mn issues.

Topic Area 3 – Response to Manganese Accumulation/Release Issues

Trends in Mn Occurrence

Accumulation. Manganese currently continues to accumulate primarily in the 337 Pressure Zone, which is served by Well C. This source has been in use since 1981, has an average Mn level of 0.05 mg/L, and is chlorinated but is not treated to remove Mn. The Southwest 337 Pressure Zone is most associated with Mn problems in the distribution system, especially since the system became chlorinated. Prior to chlorination, dissolved manganese from Well C would pass through customer plumbing, and manganese accumulation in the distribution system was mainly at dead ends and areas with higher water age. The pipe materials prevalent in this area are PVC (65%), ductile iron (20%), and asbestos-cement (15%). In the past, iron and Mn issues were found primarily in the north 337 Pressure Zone in the vicinity of untreated source B. Lacey reports that this area has some of the oldest piping and pipe materials are a mixture that is likely similar to the overall distribution system, which is 64% PVC, 23% asbestos-cement, 13 % cement-lined cast iron, and a small amount of other materials. Lacey has also indicated that Mn continues to accumulate in the vicinities of the treatment plants, since 100% removal is not achieved, and the treated sources are used more than the untreated sources Release. As described previously, the Department indicates that current complaints are generally related to particles and colored water caused by release of legacy Mn. The Department attributed these releases to changes in water quality, due to differences in the pHs of their well waters. Since 2008, Lacey has received eight to twelve brown water calls each year. Half of these (four to six) are likely caused by Mn, according to the Department. For example, in 2009, five of ten brown-water calls were clearly caused by Mn. Of these, four occurred in the 337 pressure zone.

Utility Response Measures

System Monitoring. The Department tracks customer complaints in a database, including “brown water” complaints that may be associated with iron or Mn. Additionally, as described above, the Department launched a special study to determine the causes of the brown water complaints and the most effective manner of addressing the problem. This study included sampling brown water sites within the distribution system for water properties (including pH and

©2015 Water Research Foundation. ALL RIGHTS RESERVED. conductivity), metals (including total and dissolved iron and Mn), and bacteria (including total coliform, heterotrophic plate count, iron and sulfur bacteria); a literature review, and determining mitigation strategies (including evaluation of UDF effectiveness and a recommendation for a development of a system-wide unidirectional flushing program). The study found that primary causes of the brown water episodes were the presence of iron bacteria in well supplies, intermittent treatment practices, and the presence of nutrients in source waters and added during treatment (including iron, Mn, and organic carbon naturally-occurring and from dechlorination of Well B water), which promoted growth of the iron and heterotrophic bacteria. Mains Cleaning (Reactive Flushing). Currently, complaints that appear to be associated with Mn or iron (“brown water”) result in the visit of a flushing crew to the area. The crew flushes until the water is clear. As part of its Brown Water Mitigation evaluation conducted in 2004, Lacey evaluated the effectiveness of UDF on both PVC and AC pipes. As shown in Figure 4.5, there was not a significant difference in the visual appearance of the iron and Mn film on PVC pipe after flushing. However, bulk water sampling conducted during the flushing (Table 4.6) shows that significant quantities of HPC, iron bacteria, and sulfur bacteria were removed after just 7 minutes of flushing at 6 fps versus 10 fps, and that turbidity, iron, and Mn concentrations quickly decreased to acceptable levels.

Figure 4.5 Visual inspection of PVC pipe before and after flushing at 6 fps (left) and 10 fps (right).

Approximately 57 grams of material was captured in hydrant nets with pore sizes ranging from 57-308 µm. Eighty three percent of the material captured was >308 µm in size. The PVC pipe low velocity (6 fps) trial removed 77.6% of particles >308 µm in size. Flushing at 10 fps removed an additional 22.4% of particles in this size range. Results are summarized in Table 4.8.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 4.8 Comparison of bulk water quality during flushing velocity trials on 6-inch AC pipe HPC Coliform Turbidity* Total Fe Total Mn Sample Time CFU/mL per 100 mL NTU mg/L mg/L LV 0 1:19:00 30,000 <1 17 3.51 0.18 LV 1 1:19:30 7,900 <1 38 16.4 0.31 LV 2 1:20:00 1,400 <1 7.75 1.7 0.04 LV 3 1:20:30 700 <1 1.23 1.32 0.01 LV 4 1:21:00 560 <1 0.76 0.14 0.01 LV END 1:25:00 100 <1 0.53 0.07 <0.01

HV 0 1:26:30 510 <1 1.17 HV 1 1:27:00 490 <1 1.45 0.13 0.01 HV 2 1:27:30 130 <1 0.75 HV 3 1:28:00 190 <1 0.39 0.04 <0.01 HV 4 1:28:30 160 <1 0.4 HV END 1:31:00 130 <1 0.24 0.23 <0.01 Source: Data taken from Friedman et al. 2010 * Field measurement LV = Low velocity (6 fps) HV = High velocity (10.5 fps)

For the AC pipe trial, a low velocity removal efficiency could not be calculated since the maximum attainable flushing velocity at this site was only 6 fps. However, a comparison of the quantity of material retained in the large and small nets at 6 fps is possible since both nets remained intact. Seventy-six percent of the material removed from the AC pipe was greater than 308 µm in size. Frequency of reactive flushing. The City conducts reactive flushing upon receipt of a complaint. Additionally, the City flushes the Central Business District every 3-4 years.

Equipment Fouling

The Department indicates that there was one instance in which a pressure-related complaint was caused by a service line blocked by the presence of oxidized Mn. However, Lacey typically has not experienced equipment fouling as part of their Mn and iron problems. The utility reports that sand or tree roots are more likely to result in equipment replacement.

Cost Impacts Summary: Topic Area 3 - Response to Manganese Accumulation/Release

Labor Effort. Lacey estimates that a two-person flushing crew spends one to three hours conducting this flushing. Assuming utility staff spend sixteen to twenty-four hours conducting flushing to address complaints, the Department estimates a cost of about $600 (salary only) to $900 (salary only) spent on labor to address these complaints each year. Estimate including benefits: approx.: $1,600 to $2,400. Because labor costs associated with the brown water study are not available, $20,000 for labor and equipment associated with pipe extraction, flushing evaluations, staff time for other

©2015 Water Research Foundation. ALL RIGHTS RESERVED. field labor, project management and implementation activities was estimated for the brown water study. Analytical. Analytical work associated with conducting the brown water study included bulk water and pipe slice analysis and cost $13,000. After the study was completed, the Department conducted recommended monitoring of HPC, iron, and sulfur bacteria from 2005- 2008. Analytical fees for this monitoring were $15,000. Contractor. The brown water study mentioned indicated was conducted by an outside consultant. Consulting fees for the investigation were $65,000.

Topic Area 4 – Prevention of Manganese Accumulation/Release

Triggers or Indications of Accumulation or Release

The Department indicates that complaints are generally related to particles and colored water caused by release of legacy Mn. The Department attributes these releases to changes in water quality, due to differences in the pHs of their well waters.

Prevention Methods

Treatment. Of the four sources that are associated with contributing Mn and iron to Lacey’s distribution system, Wells B and D are treated, in part, to address the presence of Mn. Permanganate and pyrolusite filtering media are used to address Mn in Well B’s treatment train. Well B’s produces an annual average of about 0.72 MGD. Greensand filtration provides Mn removal for the Well D source, which produces an annual average of 0.54 MGD of water. These two sources comprise about 40% of Lacey’s overall production. Wells C and E receive only chlorination for disinfection and annually produce about 0.27 MGD, and 0.15 MGD respectively. Flushing. The Department indicates that flushing is used to address multiple water quality issues in their system: Mn, iron, post-development rock removal, and low chlorine. Between October 2011 and May 2012, crews flushed about 106 miles of piping over 2,013 hours. The Central Business District is flushed every 3-4 years at night to minimize service disruptions. The 337 Zone is flushed annually. Table 4.9 and Figure 4.6 provide a summary of the 2011-2012 flushing season.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 4.9 Summary of preventative flushing impacts Parameter Unit 2011-2012 Preventative Pipe-Miles Flushed pipe-mile 106 Number of Days of 2 person crew days 126 Flushing Average Cleaning pipe-mile/day/crew 0.84 Rate1 Total Pipe-Miles in pipe-mile total 357 System Area Turnover % of applicable area 100% of 337 zone Total Labor for Field person-hours 2,013 Crew person-hours/pipe- 19 Normalized Labor for mile flushed Field Crew person-hours/pipe- 5.6 mile total Estimated Cost of $ 83,660 Field Crew Labor2 Normalized Cost of $/pipe-mile flushed 789 Field Crew Labor2 1Based on four 2-person crews working 8-hr shifts per day 2Based on salary plus benefits of $41.56 per hour ($29.22 salary +$12.34 benefits estimate)

Figure 4.6 Summary of Lacey’s 2011-2012 flushing season

Effectiveness of Measures

Perceived. The Department perceives their unidirectional flushing program as being effective. The Department indicates that flushing in the Southwest 337 Pressure Zone seems to help prevent accumulation of Mn in the distribution system even though loading of Mn continues since they continue to rely on untreated Well C. Additionally, Lacey indicates that heterotrophic plate counts have decreased in response to chlorination and flushing activities. There have been fewer customer complaints. Complaints are now more likely to be about black specks in the water rather than black water. Measured. The Department indicates that staff would measure turbidities of greater than 1,000 NTUs when conducting flushing in response to a customer complaint during the brown water episodes in 2002 and 2003. Now the worst turbidities measured are closer to 100 NTU. Anecdotally, the Department indicates that newer crewmembers might report “high” levels of turbidity when they measure 47 NTUs during flushing. However, in the past, 47 NTUs would not be a notable observation and turbidity was routinely much higher. The Department sees this as an indicator that much of the accumulated material has been removed from piping.

Cost Impacts Summary: Topic Area 4 - Prevention of Manganese Accumulation/Release

Monitoring. The Department is unable to provide an estimate of labor and other costs associated with Mn monitoring. Mains Flushing. The Department provided cost estimates for their unidirectional flushing program activities conducted between October 2011 and May 2012. Crews flushed about 106 miles of piping over 2,013 hours. The Department estimates that materials cost $1,500 for dechlorination and testing supplies and the labor cost (not including benefits) was $58,820. Night flushing requires the payment of overtime to crews. The only Mn–related monitoring conducted is during flushing when crews monitor turbidity to determine when flushing is completed. Reservoir Cleaning. Reservoirs are not cleaned specifically to address Mn issues, therefore, costs are not included. Release Prevention. At this time, the City does not take action or incur costs specific to avoiding release of legacy Mn. While pH variability is suspected to contribute to occasional water quality complaints, it was not viewed as necessary solely for Mn release control. The city did construct a pH-adjustment facility for a corrosive source in the south part of the 337 zone, but has not yet documented whether pH adjustment at this source affects Mn release.

Summary of Cost Impacts for All Topic Areas

Table 4.10 summarizes costs described in this case study associated with legacy Mn and iron. As discussed above, some costs cannot be assessed, such as those associated with Mn monitoring.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 4.10 Summary of Lacey legacy Mn cost impacts Absolute Impact Normalized Impact Activity and Costs1 and Costs1 Notes/Comments Customer Satisfaction

Customer complaints of 10 per year system- 1 per 2,126 Based on current water quality wide services per year water quality

Average of 10 Labor for addressing 0.0019 40 hrs/year = complaints per year customer water quality hrs/service/year = $4,000/year and average of 4 labor complaints $0.19/service/ year hours per complaint Restitution related to $1,700 customer complaints and (documented) One-time costs excursion episodes $11,900 (estimate)

Bottled water provision Not applicable during excursion episodes

Installation of 100 blow- offs for more effective $234,170 One-time costs flushing1 Lost revenue due to reduced water sales during $0 release episodes/service disruption Labor effort for public notification (door hangers, Not estimated website, media, etc.) Total cost of Response to customer $200 $0.01/service/year answering questions inquiries per year Public relations during Primarily postage brown water episodes and $18,400 One-time costs initial flushing program (continued)

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 4.10 (Continued) Absolute Impact Normalized Impact Activity and Costs1 and Costs1 Notes/Comments Co-Occurring Contaminants Labor for routine surveillance monitoring Not applicable within distribution system (including Mn) Commercial laboratory cost for routine dist. Not applicable System monitoring Response to Mn Accumulation/Release Labor for addressing customer water quality See above See above See above complaints Commercial laboratory cost associated with Not available monitoring during complaint follow-up Labor for flushing in response to metals Not applicable excursion episodes Labor for short-term distribution system Not applicable monitoring during metals excursion episodes Commercial laboratory cost during metals Not applicable excursion episode Did not conclude that $20,000 (Labor) Mn was primary cause $28,000 (Analytical of problem. However, Investigational study into fees during study Mn problems have brown water episodes and for ongoing been addressed (includes consultant and monitoring) through implementing lab fees) $65,000 recommended (Consultant) strategies. One-time costs (continued)

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 4.10 (Continued) Absolute Impact Normalized Impact Activity and Costs1 and Costs1 Notes/Comments Prevention of Mn Accumulation/Release 19 hrs/pipe-mile Labor effort for routine 2,013 hrs/year = total/year unidirectional flushing $83,660/year $789/pipe-mile (UDF) program total/year Equipment for UDF For dechlorination and $1,500 program testing supplies 1Internal costs associated with utility labor are based on Y2012 burdened labor rate of $41.56/hour. 2Rough estimate for restitution of multiple complaints.

SUMMARY OF CASE STUDY FINDINGS

Comparison of Case Study Qualitative Findings

Table 4.11 is a comparison of the qualitative findings of the case studies, broken down into the four topic areas studied by the project (Customer Satisfaction, Co-Occurring Contaminants, Response to Mn Accumulation/Release, Prevention of Mn Accumulation/Release). Viewed from a qualitative perspective, the impacts that legacy Mn may have on a utility, and the utility’s response to legacy Mn can vary widely. In the case of Park City, two intense and well-publicized colored water episodes (termed event release by this project5) caused the utility to undertake an extensive response program aimed at reassuring the public about the safety of its water and reducing the amount of legacy Mn in its system. Clearly, Park City is incurring substantial costs due to legacy Mn and co-occurring contaminants in its system. Lacey’s experience with legacy Mn is less dramatic. This utility has sponsored an investigation of legacy Mn in its system, instituted UDF as a means to help prevent the accumulation of Mn (and iron) and installed treatment at selected wells to reduce continued loading of Mn in its distribution system. Some legacy Mn episodes occur, primarily in one section of their distribution system, yet other colored water episodes occur, probably related to iron release.

Comparison of Case Study Quantitative Findings

Table 4.12 - Table 4.15 provides a summary of quantifiable legacy Mn impacts based on information compiled from the cases studies. Similar to Table 4.11, these tables divide the case study finding into the four study areas for the project. However, unlike Table 4.11, these tables focus on costs and other parameters that can be computed. Where possible the absolute costs and costs normalized by appropriate measures, for example per service connections or mile of pipe, are presented. These tables also attempt to distinguish the costs of incidental Mn release from event Mn release.

5 Event release is a term proposed by this project to describe a large scale and intense legacy Mn related colored water episode which generates wide-spread concern by customers. This is contrasted to incidental release which is used to describe a localized colored water episode, which may or may not be related to legacy Mn, and impacts few consumers

Two colored water episodes related to legacy Experience both Mn and iron related colored Mn release in potions of distribution system water episodes in part related to Mn fed by mine water containing metals. accumulation. Background

Recorded by customer complaints. Documentation of Recorded by customer complaints. Majority of complaint both iron, and Mn dissatisfaction related. Action taken to Individual customer follow-up, Reactive flushing based on customer mitigate public relations campaigns and public complaints. dissatisfaction meetings. Effectiveness of Reduced but not eliminated customer UDF program perceived to reduce Mn action concerns. complaints. Customer complaints response. Customer complaints response. 1. Customer satisfaction 1. Customer satisfaction Service interruption. Incurred costs for: Restitution (cash payment). Public meetings. Public relations. Public relations.

Inorganics Evidence of As, Pb, Tl and Hg accumulation Not measured accumulation in pipe scale.

Regulatory Some metals exceed MCL/SMCL’s in water Historically higher levels coliform bacteria in compliance issues samples taken during colored water episodes. areas of system containing legacy Mn. Contaminants Contaminants

2. Co-Occurring Water quality sampling. Cost incurred for: None Analysis of samples. (continued)

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 4.11 (Continued) Topic area Category Park City Lacey Continued accumulation in portions of Strong spatial component in Mn system served by Mn containing well, Trends accumulation likely associated with source occasional releases tied to change in water water contributions. flow direction and chemistry. Utility tracks consumer complaints. Program to respond to complaints. Utility actions Special study of colored water episodes and Reactive localized UDF program. effectiveness of UDF. One possible pressure related complaints Equipment fouling None experienced. related to Mn accumulation. Labor Labor Water quality analysis. Water quality analysis.

3. Mn Accumulation/release 3. Mn Accumulation/release Costs incurred for: Independent consultant. Independent consultant. Purchase of flushing equipment.

Customer complaints. Triggers Customer complaints. Baseline monitoring program.

Additional treatment of source. Addition of Mn treatment at source. Prevention methods Established UDF program. Establishment of UDF program. release release Labor The ‘preventative’ costs incurred are not Water quality analysis. unique to Mn. Utility would take same

4. Prevention of Mn Costs incurred for Investigation of alternative mains cleaning. actions (flushing) even if there were no Mn Purchase of flushing equipment. complaints.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 4.12 Summary of case study quantitative findings – Topic Area 1. Customer Satisfaction Park City Lacey Impact type Absolute Normalized Absolute Normalized

Customer 20/yr 1 complaint per 255 1 complaint per 2,126 10/yr complaints service connections/yr connections/yr Incidental Incidental

1 complaint per 6.8 Customer 60 in affected area service connections in Not estimated Not normalized complaints Event affected area

Public $200/yr responding $0.01/service relations Not estimated Not normalized customer inquiries connection/yr efforts Incidental Incidental > $8,300 public > $20.80 /service notification in affected connection in affected Public $18,400 public area (Y2010) area (Y2010) relations notification in affected Not normalized

Event efforts area 2 public meetings – no Not normalized cost estimate Customer restitution None Not normalized $11,900 $1,700 per complaint

Event payment (continued)

Table 4.12 (Continued) Park City Lacey Impact type Absolute Normalized Absolute Normalized

$37.50 /service Purchase $15,000 in affected connection in affected None Not normalized bottled water area (Y2010) Event area (Y2010)

$11.30 /service $4500 (in affected area connection (in affected Y2007) area Y2007)

Lost revenue None Not normalized $7500 (in affected area Event Y2010) $18.50 /service connection (in affected area Y2010)

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 4.13 Summary of case study quantitative findings – Topic Area 2. Co-occurring Water Quality Issues Impact type Park City Lacey Absolute Normalized Absolute Normalized Labor effort $0.20 /service monitoring other $1,000/yr None Not normalized connection metals. Monitoring $2.04 /service /analytical costs $10,400/yr None Not normalized connection/yr other metals.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 4.14 Summary of case study quantitative findings – Topic Area 3. Response to Mn Accumulation/release Park City Lacey Impact type Absolute Normalized Absolute Normalized

Labor effort $0.98/service $0.19/service complaint $5,000/yr $4,000/yr connection/yr connection/yr response Incidental Incidental Labor effort $1,630 /pipe mile $18,600 (Y2007) distribution flushed (Y2007) No estimate Not normalized system $4,900 /pipe mile Event $55,800 (Y2010) flushing flushed (Y2010) Analytical costs $0.80 /service $4,000 None Not normalized complaint connection/yr

Incidental Incidental follow-up. Labor effort distribution $1,200 (Y2007) Not normalized No estimate Not normalized sample $3,500 (Y2010) Not normalized Event collection Analytical Not normalized $40,000 (Y2007) costs (Y2007) No estimate Not normalized distribution Not normalized Event $200,000 (Y2010) flushing. (Y2010) $20,000 labor Other one- $25,000 (consultant Not normalized $28,000 analytical Not normalized time costs fee)

Event $65,000 consultant fee

Equipment replacement due to None Not normalized None Not normalized Mn fouling.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 4.15 Summary of case study quantitative findings – Topic Area 4. Prevention of Mn Accumulation/release Park City Lacey Impact type Absolute Normalized Absolute Normalized Labor distribution system cleaning and $23,200/yr $195 /pipe mile flushed $83,660 /yr $789 /pipe mile flushed monitoring. Other direct costs $1500/yr distribution system Not estimated Not normalized (dechlorination $14 /pipe mile flushed cleaning and chemicals) monitoring. New equipment Other one-time $234,170 adding blow- $62,000 for UDF Not normalized Not normalized costs offs flushing

The Park City case study provides an opportunity to compare the labor costs of preventative versus reactive flushing for an event release scenario. Table 4.16 presents a comparison of labor costs for reactive and preventative flushing. As previously presented in Table 4.3, for Park City the cost for reactive and preventative flushing, when normalized to person hours per mile of pipe flushed, is identical. Yet during an event release, Park City spent almost as much during release Event 1 and over twice as much during Event 2 on flushing labor as was spent on preventative flushing of the entire system. The difference was caused by the need to repeatedly flush the affected are of the distribution during event release. In the case of Event 2, the affected area was flushed the equivalent of 25 times. Hence for Event 2, the labor cost of reactive flushing, on a per mile flushed basis, was 25 times that of preventative flushing. The Park City case study clearly exemplifies how rapidly cost can mount for flushing during a colored water event, and can exceed the yearly cost of preventative flushing.

Table 4.16 Comparison of labor cost for reactive and preventative flushing – Park City Reactive Flushing Preventative Flushing Normalized Area Normalized Area Episode Absolute $/mile flushed Turnover Absolute $/mile flushed Turnover Event 1 825% $18,600 $1,630 100% (Y2007) affected area $23,200 $195 entire Event 2 2,465% $55,800 $4,900 system (Y2010) affected area

However, this is not to imply that preventative flushing will completely avert Mn release and alleviate the need for reactive flushing. As summarized below, both case study utilities perform preventative flushing, yet these utilities still experienced either incidental or event Mn release. However, all of these utilities believe regular preventative distribution system flushing is an important tool in improving overall distribution system water quality.

Effectiveness of Preventative Flushing

The case studies show that preventative flushing will not completely avert Mn release or alleviate the need for reactive flushing. In fact, Park City experienced its second major colored water event after a UDF program was established in the legacy Mn impacted area. (However, UDF was performed at a relatively low velocity of 3 fps.) Studies performed by both Utilities Park City and Lacey indicated that flushing was effective in removing accumulated particles containing Mn from pipes but do not remove hydraulically-resistant films adhering to pipe wall. Hence, more aggressive measures are required to remove adherent Mn films or scales on pipe walls. Nonetheless, all of the case study utilities perform preventative flushing, and believe that regular preventative distribution system flushing is an important tool in improving overall distribution system water quality.

Inherent Impacts of Accumulated Mn

It is important to note that neither the case study utilities, nor any of the survey utilities, could provide a cost that was inherently associated with the actual presence of accumulated Mn

©2015 Water Research Foundation. ALL RIGHTS RESERVED. in distribution systems. None of the utilities reported the need to regularly replace equipment (valves, sensors etc.) due to the accumulation of Mn. As discussed in the literature review, the accumulation of Mn in distribution system piping can increase pipe friction and thereby increase pumping costs. However, increased costs due to legacy Mn could not be demonstrated by any data available to the project. One may anticipate that biological growth potentially promoted by legacy Mn would adversely affect disinfectant residual stability. Hence, the absence of legacy Mn should improve disinfectant residual stability. Yet the project was unable to find an example directly relating disinfectant residual stability to the absence of accumulated Mn. All of the case study utilities believe that a regular flushing program improves residual stability, but the extent that the absence of legacy Mn contributes to a residual with greater stability is unclear. The Lacey case study does support the observation that accumulated Mn encourages the growth of biofilms that may serve as a refuge for bacterial growth. Lacey observed of higher levels of iron and sulfur, as well as coliform and heterotrophic bacteria, in portions of the distribution system containing legacy Mn. Ultimately the utility instituted system-wide chlorination in part to eliminate non- acute coliform violations in its distribution system. Nonetheless, the presence of accumulated Mn is of great concern to Park City. This is not specifically because of its presence in the distribution but because of its potential for mobilization along with the release of co-occurring metals. This concern has caused to utility to undertake an extensive distribution sampling program as a trigger to anticipate the release of Mn and co-occurring metals prior to a visible colored water episode. Overall, a seeming simple but important conclusion is that the major risk associated with legacy Mn is not its actual presence in distribution systems, but its potential for release. As long as legacy Mn remains stable in the distribution system and does not release in a colored water event, its impacts are hard to discern and its costs appear to be relatively small.

TERMINOLOGY

In the context of deposit accumulation, the term “occurrence” typically refers to the concentration of a particular element or contaminant in the solid phase. Occurrence results are typically expressed on a dry mass basis, most notably in micrograms per gram of dry solid (i.e., parts-per-million) for trace elements or as a weight percent (wt %) for more common elements such as Mn. Such results represent a relative concentration in that the occurrence of a particular element is (inversely) dependent on the mass of other elements present in the sample. For example, Mn occurrence of a given deposit sample is “diluted” to lesser levels by co-occurrence of large amounts of sediment or corrosion scale. In contrast, the term “inventory” refers to the absolute mass of a particular element in a sample, independent of the presence or the amount of co-occurring elements. Inventory is typically expressed normalized to the length, internal surface area, or internal volume of a pipe segment. Occurrence and inventory are related parameters, with the unifying variable being the total mass of deposit. Two separate samples could have the same Mn occurrence, but if the total mass of one sample were larger than the other, it would have a correspondingly larger Mn inventory. Conversely, two separate samples could have the same normalized Mn inventory, but if one sample has more or less of other co-occurring solids, then the occurrence of Mn will differ between them. Therefore, in order to reliably determine Mn inventory for a given site or sample, it is necessary to have knowledge of both total mass and composition. These two parameters—occurrence and inventory—serve separate purposes in terms of understanding distribution system impacts on water quality. Mn inventory within utility distribution systems is particularly useful with respect to providing a context for Mn-based accumulation and release impacts to utilities and customers; therefore, it is the emphasis of the current research project. Estimates of length-normalized mass (mg/ft) allow for conceptual determination of total Mn inventory in a particular system. Estimates of volume-normalized mass (mg/L) allow for determination of Mn concentration “excursions” that could occur under a specific release scenario, e.g., as a function of the amount or percent of material released into the water column.

ASSESSMENT APPROACH

Development of Mn inventory estimates specific to the utility participants in this study would require physically digging up pipe and characterizing deposit mass and composition. This requires a considerable degree of effort and is beyond the scope of this desktop project. Therefore, the project team sought to develop a more general understanding of Mn inventories and associated risk factors in representative distribution systems from around the country by utilizing available data from the literature review. To-date nearly all published investigations of accumulation have focused on contaminant occurrence in distribution systems (Lytle et al, 2004; Friedman et al, 2003) and service lines (Schock et al, 2008). These studies focused on composition of deposits without direct concern for the same-sample mass amounts, except insofar as sufficient mass was obtained to support

©2015 Water Research Foundation. ALL RIGHTS RESERVED. analytical activities. Since same-sample normalized mass quantities were not determined or reported, the Mn occurrence data from these studies cannot be readily applied to determine Mn inventory. Friedman et al. (2003) estimated Mn inventory per unit of pipe surface area for several utilities by collecting and analyzing carefully-timed discharge water samples during unidirectional flushing trials and normalizing the results back to the pipe size (see Table 5.1). However, the results represent only those Mn solids which were hydraulically-mobile under the flushing conditions applied. Total Mn inventory includes the material that remained intact on the pipe surface throughout the flush, which was not determined but would presumably be higher due to the hydraulically-resistant nature of Mn films. In a more comprehensive exploration of inorganics accumulation in water distribution systems (WRF #3118), Friedman et al. (2010) obtained 46 pipe specimens from 20 different utilities and characterized same-sample deposit quantity and composition. Using this primary data, the researchers developed and applied methods to estimate pipe surface area-, length- and volume-normalized mass inventory for trace inorganic elements. Mn inventory estimates were not directly developed as part of that project, although the data needed to do so was generated and reported. Considering the occurrence-style approach used in the investigation and the quality and quantity of the data obtained, it was determined that it presented the best opportunity to broadly characterize Mn inventory levels in distribution systems. Therefore, the methods described in WRF #3118 have been extended to the Mn composition data obtained in the same investigation to develop Mn inventory estimates. For context of interpreting results, it was noted that 11 of 20 utility participants reported and/or were found to currently serve water with Mn at concentrations between 0.01 and 0.05 mg/L in entry-point or distribution system water samples. None of the utilities supplied water with Mn in excess of 0.05 mg/L under current conditions, although several reported the historical use of sources with Mn levels above the secondary MCL. Six of the utility participants reported having installed dedicated iron and Mn removal processes at problem sources to control Mn loading to their system.

INVENTORY RESULTS

Inventory estimates were developed for the entire sample set (n=46), as well as segregated into subsets corresponding to the following pipe type groupings: unlined cast iron (n=22); ductile and galvanized iron and steel (n=12); and cement-lined and plastic (n=12). This breakdown was done to maintain consistency with the approach used in WRF #3118. However, it should be noted that pipe type is only one of several variables that influence Mn inventory. More prominent variables include current and historical Mn concentrations in the bulk water, local hydraulic conditions, and maintenance practices. Recognizing the large variability in these parameters resulting from the relatively small sample sizes involved with each pipe type, the data analysis activities described below were focused on the collective sample set. Figure 5.1 presents the cumulative percentile distributions for area-normalized, length- normalized, and volume-normalized Mn inventory for these sample sets. Note that the abscissa on each graph have been set such that any data points to the left of the y-axis represent samples for which an insufficient amount of mass could be obtained to support compositional analysis. Table 5.1 provides a statistical summary of the various normalized Mn inventory parameters. Because the results span several over 4 orders-of-magnitude and are not normally distributed, emphasis should be placed on median levels (and other key percentiles) in lieu of average levels.

©2015 Water Research Foundation. ALL RIGHTS RESERVED. With respect to pipe area, the median Mn inventory was 210 mg/ ft2. General comparison to the results obtained in Friedman et al. (2003) lends further support to the limited effectiveness of flushing for removal of Mn; the hydraulically -mobile Mn inventory in those cases ranged from 0.6 to 35.7 mg/ft2. With respect to pipe length, the median Mn inventory was 300 mg/ft or 55 mg/ft/inch pipe diameter. Based on the latter parameter, this translates into a median Mn inventory of 3.8 lbs per mile for 6-inch diameter pipes and 7.7 lbs per mile for 12-inch diameter pipes. With respect to internal pipe volume, the median Mn inventory was 70 mg/L. At this level, only 1.5% of the deposit matrix would need to be released to cause an exceedance of the EPA 1- day and 10-day Health Advisory Value for Mn (assuming the Mn was homogenously distributed and there was negligible contribution from background Mn).

80% A 60%

40%

Sample Percentile 20%

0% 0.1 1 10 100 1000 10000 100000 Manganese Accumulation (mg/sft)

All Pipe Specimens Unlined Cast Iron Ductile a nd Ga lva nized Cement-Lined and Plastic 100%

80%

60% B

40%

Sa mple Percentile 20%

0% 0.1 1 10 100 1000 10000 100000 Manganese Accumulation (mg/ft)

All Pipe Specimens Unlined Ca st Iron Ductile and Galvanized Cement-Lined and Plastic

100%

80% C 60%

40%

Sa mple Percentile 20%

0% 0.1 1 10 100 1000 10000 100000 Manganese Accumulation (mg/L)

All Pipe Specimens Unlined Cast Iron Ductile and Galvanized Cement-Lined and Plastic

Figure 5.1 Cumulative percentile Mn inventory profiles for pipe specimen deposit samples collected and analyzed by Friedman et al., 2010 based (A) on mg Mn per ft2 pipe wall area, (B) on mg Mn per liner foot of pipe length and (C) on mg Mn per pipe volume in liters

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©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 5.1 Statistical summary of Mn inventory parameters for all pipe specimen deposit samples collected and analyzed by Friedman et al., 2010 Normalization Average Standard Minimum 10th Median 90th Maximum Parameter Units Result Deviation Result Percentile Result Percentile Result Surface Area mg/sft 1,070 3,770 NS(a) NS 210 720 23,950 Length mg/ft 1,400 4,280 NS NS 300 1,060 25,080 Length* mg/ft/in 280 990 NS NS 55 190 6,270 Volume mg/L 410 1,590 NS NS 70 305 10,150 mg- Volume* 1,810 6,400 NS NS 350 1,220 40,600 in/L NS = insufficient mass for analytical activities.

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RISK-BASED APPROACH FOR DEVELOPING A RESPONSE TO LEGACY MANGANESE

A number of factors should be considered when determining an approach for responding to the presence of legacy Mn. First, Mn is not a currently a primary regulated contaminant, and in most states utilities are not required to control the levels of Mn entering their distribution systems. Second, the presence of legacy Mn in distribution systems is not necessarily problematic in and of itself; it is the potential for mobilization of Mn that poses a risk for utilities. Legacy Mn may remain stable or immobile over extended periods, perhaps indefinitely, but if a large-scale (event) release occurs, the consequences can be severe for a utility. An extensive colored water episode can seriously damage consumer confidence in a utility. Additionally, the potential for the release of regulated co-occurring metals during a Mn episode may be an even greater concern, since their release may represent a risk to public health. Utilities clearly have a responsibility to protect public health and maintain the confidence of their consumers. Yet at the same time, utilities must constantly determine where best to apply their financial and human resources. In order to balance these responsibilities, utilities should consider a risk-based approach for responding to legacy Mn, which recognizes both the likelihood and the consequences of a legacy Mn related episode. When deciding how to deal with legacy Mn, utilities should assess the extent that legacy Mn (as well as other co-occurring trace inorganics) has accumulated in their system and the likelihood and consequences of release. Complicating the picture is that Mn-related colored water episodes may be due to release of legacy Mn within the distribution system or due to changes in Mn levels in source waters, inadequate Mn treatment or the failure of Mn treatment, resulting in pass-through Mn episodes. Utilities must be careful not to misidentify pass-through episodes (whose origins are source water variability or inadequate treatment), with those caused by distribution system release episodes, which is the focus of this project. There is no universal criterion for determining the acceptable level of risk for a Mn episode. Clearly, a large-scale event release of legacy Mn, causing general concern by customers along with the potential release of regulated metals, is to be avoided. But the practical question faced by a utility is if additional measures, beyond those associated with good distribution system operating and maintenance practice, are needed to deal with legacy Mn in their system. Best management practices (BMPs) for the control and management of legacy Mn proposed later in this chapter may assist utilities.

UTILITY SELF-ASSESSMENT FRAMEWORK

A self-assessment framework has been developed for utilities to follow to help determine the level of risk associated with the amount of Mn entering their systems, the potential for Mn accumulation and release, and the effectiveness of their Mn mitigation strategies. This

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©2015 Water Research Foundation. ALL RIGHTS RESERVED. framework also provides guidance to utilities for developing responses to legacy Mn. The overall process is presented in Figure 6.1. A four-step self-assessment approach is suggested as follows:

Step 1. Gather Information to Respond to Four Risk Assessment Questions (See Figure 6.1) Step 2. Determine Risk Level (Low, Medium, High) for Each Question (See Tables 6.1 –6.4) Step 3. Perform Assessment of Potential Impacts/Costs (See Figure 6.1 and Tables 6.5 –6.8 for Participating Utility Experiences) Step 4. Step 4. Take Steps to Reduce Risk Where Appropriate (Implement Practices Identified in Table 6.9)

Four basic questions are posed in the framework. Starting with the upper left-hand side, with the question “Is or has Mn entered the distribution system?” The reader answers each question in stepwise fashion. In some cases, the answer to each question is straightforward, in other cases determining the answer may be complicated by the number of sources of supply, changing source water quality, and distribution system operations and maintenance practices. In some instances, it may be possible that the utility does not collect the type of information needed to conduct the self-assessment. In this case, the utility should identify these areas as data gaps that should be eliminated prior to completing the risk assessment. To assist utilities in determining their conceptual risk level, suggested typical characteristics of each risk level are presented in Tables 6.1–6.4. A simple scale of low, medium, and high risk has been selected to allow utilities to relatively quickly perform this assessment and to help identify where resources may be best allocated. Obviously, a more detailed risk assessment scale could be used, although that would likely unnecessarily complicate the assessment process, and ultimately, the frequency and magnitude of Mn accumulation and release issues is highly system-specific. The findings from the literature review, utility surveys, and utility case studies indicate that the degree of Mn accumulation and the magnitude of associated impacts can vary widely between systems and even within systems. A general and important finding of this project, however, is that Mn accumulation in and of itself causes fewer undesirable outcomes compared to Mn release. Thus, it is possible that a utility may find themselves in the “High” category for several of the loading and accumulation risks factors, but may still have low overall risk for release and negative outcomes. This might be the case if distribution system chemistry, hydraulics, and main cleaning programs are effective and stable. Conversely, a utility may have relatively low Mn loading, but poor main cleaning and frequent chemistry changes may cause more frequent events of larger magnitude. Thus, this categorization scheme is not intended to predict whether problems associated with legacy Mn are likely to occur, but rather to help utilities determine if further action to reduce risks associated with legacy Mn accumulation and release is warranted.

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To assist in matching risk to appropriate response, potential impacts and related costs at various levels of risk are listed in the self-assessment framework (Figure 6.1). The boxes also refer to an additional set of tables (Tables 6.5–6.8) summarizing project findings for each of the potential impacts. Lastly, a set of BMPs developed by the project, which help reduce the risks posed by legacy Mn is presented in Table 6.9. These BMPs can assist utilities in setting goals to minimize their risk for the accumulation and release of legacy Mn.

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©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 6.1 Risk assessment factors—Mn entering the distribution system Risk Level Factor High Medium Low Point-of-entry Mn  Typically >0.05 mg/L, and/or  Typically 0.02 to 0.05 mg/L,  Typically < 0.02 mg/L concentration frequent significant excursions infrequent excursions  Highly variable with  Somewhat variable with  Consistently ≤0.01 mg/L Source water Mn unpredictable spikes in Mn predictable patterns  Low variability, rarely variability  Highest concentrations in  Infrequent Mn spikes above exceeding 0.02 mg/L excess of 0.05 mg/L 0.05 mg/L  Source water Mn >0.05 mg/L  Source water Mn level ≤0.05  No specific Mn treatment and sequestration used as mg/L and sequestration is used process used due low level of treatment approach in lieu of oxidation/removal of Mn in source of supply and Mn treatment  No process used to Mn treatment chemicals practice oxidize/remove Mn  Sequestration has been  High water age results in demonstrated to generally breakdown of sequestering control Mn within distribution agent in distribution system system  Treatment process difficult to  Treatment process is  Treatment readily achieves Mn optimize moderately stable and optimal target of <0.01 mg/L  Optimal chemical dose chemical dosages readily  Treatment easily adjusted for hampered by changing Mn achieved any changes in source water Mn treatment concentrations  Adequate process monitoring quality performance  Inadequate process monitoring performed causes frequent Mn  Treated water Mn usually breakthrough <0.02 mg/L  Treated water often >0.02 mg/L (continued)

©2015 Water Research Foundation.106 ALL RIGHTS RESERVED. Table 6.1 (Continued) Risk Level Factor High Medium Low  Known Mn contamination of  Contaminant-associated Mn  Chemicals likely to have Mn one or more treatment can be oxidized/removed contamination are not used Treatment chemical chemicals during treatment Mn contamination  Difficult to oxidize/remove Mn within treatment train  Mn very likely to  Mn accumulation/release  Mn accumulation/release accumulate/release in treatment within plant occurs but patterns within plant processes does not Accumulation/release process (e.g. sediments in are predictable and can be occur to a significant level within treatment backwash water holding tank) controlled  If Mn release occurs, plant  Mn release is unpredictable  Released Mn concentration concentration <0.02 mg/L and often exceeds 0.05 mg/L usually <0.05 mg/L and does not over-load removal capacity  At least one source previously  Historical sources known (or  Previously used sources known used likely to have elevated very likely) to have moderate to have been 0.01 mg/L Historical water ≤ Mn (i.e. >0.05 mg/L) and Mn concentration (0.02 to 0.05 sources used  Treatment provided when treatment not previously mg/L) using previous supply provided

Table 6.2 Risk assessment factors—Mn accumulation in the distribution system Risk Level Factor High Medium Low  Brown/black staining of  Some staining observed or  Brown/black staining rarely or household fixtures, field reported in localized areas never occurs analytical equipment, storage  Mn sometimes but not always  Mn typically <0.05 mg/L in facility interiors and >0.05 mg/L in flushed water and flushed water and rarely observed appurtenances often observed on pipe specimens on pipe specimens and/or coupons  Difficulty maintaining and/or coupons  Other regulated metals rarely disinfectant residual due to  Other regulated metals detectable detected in flushed water increased demand/biofilm, but not elevated in flushed water  Other regulated metals are non- especially evident on non-scale  Other regulated metals have been detectable in the source water and forming pipe measured, but rarely detected have been measured but not  Mn frequently measured in above background levels within detected within distribution flushed water distribution system bulk water. system bulk water. Evidence of  Other regulated trace metals  Some evidence of increased  Staining rarely observed by utility accumulation elevated in flushed water (lead, disinfectant demand, but personnel or customers thallium arsenic, etc.) primarily in areas with scale-  Causes of disinfectant demand are  Other regulated metals detected forming pipe understood and well-managed by above background levels within utility distribution system bulk water.  Mn identified by lab analysis of distribution system pipe specimens and/or coupons  Specific portions of distribution system with frequent colored water complaints  Equipment/instrumentation damage (continued)

Table 6.2 (Continued) Risk Level Factor High Medium Low  Areas closer to POEs with  Many system dead-ends are  Areas of system with routine flow elevated Mn equipped with blow-offs to velocities ≥4 fps may be  Significant areas of the improve flushing performance considered “self-cleaning” distribution system known to  Small amount of the system  System dead-ends are equipped have low flow/stagnant conditions constructed of scale-forming pipe with blow-offs and adequate Distribution System contains numerous dead- velocity can be achieved system design  ends and is poorly looped throughout the system  Significant number of water  System constructed of primarily mains constructed of scale- non-scale-forming pipe forming pipe (such as unlined  Areas spatially distant from POEs cast/ductile iron or galvanized) with Mn

Table 6.3 Risk assessment factors—Effectiveness of mitigation measures for Mn accumulation Risk Level Factor High Medium Low  Flushing is performed  Conventional flushing performed  UDF program in place and infrequently reasonably frequently performed regularly  Conventional and/or dead-end  UDF is performed (but  UDF velocities often ≥6 fps flushing only (not UDF) irregularly), velocities ~4 fps  The need for alternate main  Alternate main cleaning typically achieved cleaning technique, such as techniques not used  Tank cleaning performed swabbing or ice pigging has been Distribution  Tank cleaning is performed irregularly assessed and/or performed to system O&M infrequently  Sources with elevated Mn can be improve removal of Mn-  Sources known to contain isolated to specific areas and/or containing scales/films from non- elevated Mn not readily isolated zones scale forming pipes. to specific area or zone(s) of the  Adequate disinfectant residual is  Tank cleaning performed system maintained throughout most of according to a regular schedule  Adequate disinfectant residual not the system  Adequate disinfectant residual maintained throughout the system maintained throughout the system

Table 6.4 Risk assessment factors—Mn release in the distribution system Risk Level Factor High Medium Low  Frequent changes in flow velocity  Moderate frequency of changes in  Changes in flow velocity of greater than 100% flow velocity of greater than generally limited to less than  Use of conventional flushing only 100% 100% within the system grid  Significant changes in flow  System can be operated to  Poor pressure management direction are understood and can minimize impact of flow resulting in pressure be managed, to some degree variations transients/water hammer  Conventional flushing limited to  UDF used within the system grid.  Changes in flow direction, dead-ends for purposes of bulk Gentle bulk turnover conducted at especially with system-wide water turnover. dead-ends. Monitoring conducted impacts (e.g. change in location  Moderate occurrence of main to demonstrate stable water Physical of the source of supply, breaks and construction activity chemistry when flushing is introduction of new source, on/off terminated. well cycles)  Low occurrence of main breaks  Frequent main breaks  Construction activity not  Significant construction activities significant enough to disturb pipe causing physical disruption to scales pipe scale/accumulated Mn  Pressures have been assessed using data loggers at high and low points within the distribution system are and stable (±10 psi variation) on a daily basis

(continued)

©2015 Water Research Foundation.111 ALL RIGHTS RESERVED. Table 6.4 (Continued) Risk Level Factor High Medium Low  Recent change in source of supply  Limited changes in water  A single source of supply is used or significant change in treated chemistry (e.g. pH fluctuations or multiple sources have very water quality <0.5 units, ORP maintained) similar water chemistry  Changes in water chemistry:  Waters blended in the system  Blending ratios of multiple  Decrease in pH >0.5 units, have relatively similar water sources can be controlled within Chemical especially at pH ≤8.0 chemistries (pH, Mn content, desirable ranges (pH, Mn  Decrease in ORP >100 to disinfectant residual type and concentration, disinfectant 200 mV concentration) residual type and concentration  Changes in blending scenarios  Changes in disinfectant residual can be maintained) within the distribution system concentration but not necessarily  Change in disinfectant type disinfectant type

Table 6.5 Potential impacts of Mn pass-thru episode Project Findings Potential Impact Qualitative Quantitative  Must take action to mitigate  Restitution costs of up to $1,700 Staining/spotting due to Mn customer complaint per complaint reported.  All utilities concur that Mn  No cost information gathered for episode erodes customer pass-thru event, but costs could be Loss of customer confidence confidence. similar to large-scale event release.  Utilities may not be successful in regaining customer confidence.  Extensive reactive flushing  No cost information gathered for Need for reactive flushing needed to clear impacted area. pass-thru event, but costs could be similar to large-scale event release.

Additional information regarding pass-thru event impacts and costs can be found in Table 4.11, Table 4.12, and Table 4.16.

Table 6.6 Potential impacts of Mn accumulating in distribution system Project Findings Potential Impact Qualitative Quantitative  Evidence of the accumulation of  Unable to gather sufficient Regulated inorganic chemicals inorganic contaminants with Mn information to document cost. may co-occur with Mn at Park City.  Evidence of accumulated Mn  Unable to gather sufficient encouraging growth of biofilms in information to document cost literature and observed at Lacey. specifically due to Mn induced Disinfectant residual stability increase in biological activity. and biofilm formation  Addition costs would be associated with maintaining disinfectant residual.  Reported in literature but not  Unable to document additional documented by participating pumping cost. utilities. Unlikely to be widespread issue Impact to pumping cost due to  since weight percent of scale Mn scale formation related by Mn is small. Literature review indicated wt% of Mn in pipe scales is typically 1% or less.  Possible release of co-occurring  Labor and analytical for inorganics at levels exceeding monitoring distribution system for Increased monitoring for Mn MCL possible. metals release: $1.12 - and of co-occurring inorganics  Monitoring of possible metals $2.24/service connection from release desirable case study  Anecdotal reports of damage to  Unable to document cost but Possibility of equipment instrumentation by surveyed overall probably not a major cost. damage in distribution system utilities.

Additional information regarding accumulation and related costs can be found in Table 4.11 and Table 4.13.

Table 6.7 Potential impacts of maintaining low risk for Mn release Project Findings Potential Impact Qualitative Quantitative  Case study utilities believe  Field labor effort: $157 - preventative flushing is $789/pipe mile flushed Cost of preventative mains beneficial, and would flush if  Note: planning labor costs per mile cleaning program Mn were problem or not. for development of UDF program can be greater than field labor cost per mile Cost to maintain and improve No information collected chemical and hydraulic stability Reduced need for reactive No information collected flushing and monitoring

Additional information regarding lowering Mn release risks and related costs can be found in Table 4.11, Table 4.15, and Table 4.16.

Table 6.8 Potential impacts of being at high risk for Mn release Project Findings Potential Impact Qualitative Quantitative  All utilities concur that Mn  Complaints can reach up to 1in10 episode erodes customer connections in zone impacted by Loss of customer confidence confidence. Mn release.  Utilities may not be successful in regaining customer confidence.  Must take action to restore  Cost of > $20/service connection Public relations costs consumer confidence. in area impacted by Mn event release recorded by Park City.  Developing UDF program more  Capital investment can be large: costly than conventional Park City invested $62,000 for Cost to develop/implement UDF program equipment Lacey invested or other main cleaning program $234,000 for adding blow-offs to distribution system  Reactive flushing is employed to  Costs ranged from $19,000 - respond to colored water $56,000 for an event release. episodes. Where feasible, UDF is more effective than conventional flushing.  Unit costs for flushing due to Additional cost for reactive incidental or event release were flushing similar. However, the total cost for event release was much greater than incidental release because, in the case of event release, flushing of the impacted area of the distribution is repeated numerous times. (continued)

Table 6.8 (Continued) Project Findings Potential Impact Qualitative Quantitative  Utilities should develop a  Cost ranged from $0.15 - response plan, although not all $0.98/service connection for an Responding to complaints utilities have such a plan in event release. place.  Water quality monitoring may  Costs ranged from $40,000 - not be necessary for reactive $200,000 for event release. flushing during incidental release. Extensive water quality Event release should trigger monitoring  extensive monitoring, particularly when release of co- occurring contaminants is possible  During event release a utility  Costs ranged from $25,000 - will probably need to engage $65,000 for special studies related Costs of laboratory services or outside resources such as to event Mn release. consultants consultants or analytical laboratories Potential public health impacts No information collected

Additional information about impacts and costs of being at a high risk for Mn release can be found in Table 4.11, Table 4.12, and Table 4.14.

Table 6.9 Example best management practices to minimize the risk of Mn accumulation/release in distribution systems Location Practice Recommendation/Criteria  Source Mn < 0.02 mg/L  Low variability in Mn concentration Source water selection  Low concentration of regulated co-occurring metals  A single source of supply used or multiple sources with similar water chemistry

Source  Blend to limit Mn concentration < 0.02 mg/L  Blend to minimize variability in Mn levels Source water blending  Blend to minimize variation in water quality, particularly pH and disinfectant type  Treatment required when source Mn > 0.05 mg/L  Treatment should be considered when source Mn > Mn treatment practice 0.02 mg/L  Mn removal preferable to sequestration  Treatment should consistently achieve Mn target of <0.02 mg/L Mn treatment  Treatment should accommodate variability in source performance water Mn concentration  Treatment should accommodate changes in source

Plant/POE Plant/POE water quality  Mn levels in treatment chemicals monitored Treatment chemical Mn contamination  Chemicals likely to have Mn contamination not used Control of Mn  Mn not allowed to accumulate within plant accumulation/release  Mn containing residuals stream well managed to within treatment plant preclude release and recycle of Mn (continued)

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©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 6.9 (Continued) Location Practice Recommendation/Criteria  Adequate disinfectant residual maintained Disinfectant residual throughout the system control  Causes of disinfectant demand are understood and well-managed by utility  Adequate flow conditions maintained throughout the distribution system  System dead-ends are equipped with blow-offs and Distribution system adequate velocity can be achieved throughout the design system  System constructed of primarily non-scale-forming pipe  UDF program in place and performed regularly  Where possible UDF velocities exceed 6 fps  Alternate main cleaning technique, such as Distribution system swabbing or ice pigging performed to improve maintenance removal of Mn-containing scales/films from non- scale forming pipes.

Distribution system Distribution  Tank cleaning performed on regular schedule  No excessive biofilm formation  Blending ratios in DS controlled within desirable ranges (pH, Mn concentration, disinfectant residual type and concentration)  Changes in the flow direction and velocity generally Distribution system limited to less than 100% operation  System operated to minimize impact of flow variations  Monitor occurrence of main breaks  Monitor construction activity significant enough to disturb pipe scales

APPLICABILITY OF SELF-ASSESSMENT FRAMEWORK PROCESS

The issue of legacy Mn is complex. The self-assessment framework is not intended to be a ‘cookbook’ exercise that provides a simple answer regarding what a utility should do about legacy Mn. Instead, the self-assessment is a process designed to provide information gained from survey and the cases studies for utilities to use in understanding the risks associated with legacy Mn. By better understanding the risk and consequences of legacy Mn, the potential impacts of a Mn release episode can be compared to cost of prevention. In this way, a more informed decision can be made regarding what resources should be allocated to legacy Mn. The example BPMs for reducing Mn loading, reducing existing legacy Mn inventory, and minimizing release potential provide targets for utilities to consider meeting to reduce risks associated with legacy Mn. By following the self-assessment process, the impacts of decisions a utility makes regarding legacy Mn can be better understood.

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Chapter 1 of this report described legacy Mn as a puzzle consisting of four interlocking pieces: i) regulatory and public health, ii) aesthetic and customer acceptance, iii) utility equipment and customer devices and, iv) labor, energy and other resources. Based on information gathered from the literature review, utility surveys and case studies, this conceptualization of the legacy Mn problem is valid. While the desktop nature of this project was not intended to fully investigate each of these areas, a number of conclusions can be drawn from the information gathered through project activities. These are summarized below. Additional research needs are also identified to further understand the occurrence and impacts of legacy Mn on the drinking water utilities.

PROJECT CONCLUSIONS

The Nature of Legacy Mn

The existence of legacy Mn is documented in the literature and by utilities participating in this project, although the amount of legacy Mn present in distribution systems and associated impacts are highly variable. As discussed in the literature review, numerous studies have found Mn in distribution system pipe scale. The literature review presented a compilation of pipe scale samples taken from 29 utilities in which Mn levels in scale ranging from 14 to 10,200 micrograms of Mn per gram of scale. Thus, Mn usually accounts for less than ≤1% of total scale. The existence of legacy Mn in distribution systems is also confirmed by its presence in hydrant flush solids. A compilation of hydrant flush solids from 20 utilities presented in the literature review documented Mn levels in hydrant flush solids of up to 10,500 micrograms of Mn per gram of solid (approximately 1.5% of mass removed). With regard to Mn inventory, further data analysis conducted as part of this project of 46 pipe specimen deposit samples collected for the WRF 3118 project Assessment of Inorganics Accumulation in Drinking Water Systems Scales and Sediments estimated a median Mn inventory of 210 mg/ft2 or 3.8 lbs per mile of Mn deposit in a 6-inch diameter pipe. Of the ten utilities that participated in the project, six have experienced colored water events in their distribution system. Four utilities could identify specific portions of their distribution systems that were prone to colored water events related at least in part to the release of legacy Mn. But the presence of legacy Mn cannot be predicted a priori. Numerous factors play into Mn accumulation that cannot be numerically quantified. A colored water episode originating in the distribution system is a possible indication of the presence of legacy Mn. But the absence of such events is not proof that legacy Mn does not exist in the system. Given the lack of predictability and highly variable nature of Mn accumulation as well as the range of impacts associated with release (including “incidental” to actual “events”), utilities should understand the risks posed to their system by legacy Mn and formulate their response to legacy Mn based on an assessment of their risk. The findings of this project suggest that the accumulation of legacy Mn does not appear to have detrimental effects on the day-to-day operation of distribution systems beyond that associated with the presence of any pipe scale. Hence, the impacts and cost of legacy Mn are not great until a release episode occurs.

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©2015 Water Research Foundation. ALL RIGHTS RESERVED. Yet two features of Mn chemistry make it a special problem for utilities. First, the stability of legacy Mn is sensitive to changes in water quality conditions6. Second legacy Mn is a good scavenger of other trace inorganics. These features provide the potential for Mn to rapidly mobilize and cause colored water episodes while releasing scavenged metals. Utilities need to understand their system-specific vulnerability and guard against this problem.

Problems Associated with the Presence of Legacy Mn

In most cases, the presence of legacy Mn in a distribution system does not impose an immediate problem for a utility. The presence of legacy Mn may promote biofilm growth on pipe wall deposits that may adversely influence residual stability, taste, odor, and color of the distributed water. However, in many cases, especially where iron is co-occurring in the source water or where there are significant quantities of unlined iron scale-forming pipes, Mn only represents a small fraction of the total mass of pipe wall deposits that can support biofilm growth. The deposition of Mn coatings has been reported to impact the performance of sensors and instrumentation, but the utilities participating in this project did not identify this as a significant concern. Lastly, the formation of scale in piping can increase pipe wall friction as indicated by a reduction in Hazen-Williams C factors. Again, legacy Mn contributes only a small fraction to the total mass of the scale. In general, for the utilities that participated in this project, the actual presence of legacy Mn only causes a minor nuisance. The true problem of legacy Mn occurs if it is mobilized thereby often causing a colored water episode. As demonstrated by the case studies, these episodes can be quite costly and erosive of public confidence in a utility. In addition, depending on the current and historic source water quality supplying the system, a colored water event carries with it the possible release of regulated co-occurring metals adsorbed to scales containing Mn in the distribution system. This release of regulated metals likely represents a greater public health risk than that associated with the release of Mn. It is important to note that if releases are caused by changes in chemistry and metals are released in the soluble form, there may be little visual indication of a water quality upset beyond any discoloration caused by Mn.

Understanding the Differences Between Mn Pass-through and Mn Release Episodes

While performing the survey it became clear that it was not easy to define a colored water episode. Colored water issues are mostly brought to a utility’s attention via a customer complaint. But often the complaint is vague or unreliable and the problem may have already gone away by the time a utility is able to send a crew to respond to the complaint. Even if the colored water complaint is confirmed, it may not be very important to determine if the episode is truly related to Mn (versus iron, etc.). This is because the most likely response to the episode, no matter what the cause, is reactive flushing. On the other hand, utilities need to be alert to broader underlying trends, which may be hidden in the routine issues that arise in the daily operation of distribution systems. Utilities need to distinguish between pass-through and release episodes, since sources of these episodes are fundamentally different. Pass-through episodes are related to a failure of or the absence of treatment. In other words, the cause of the problem is Mn at the source passing

6 Example problematic changes to water quality include lowering distribution system pH, or the likely reduction in ORP caused by conversion from free chlorine to chloramine residual.

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©2015 Water Research Foundation. ALL RIGHTS RESERVED. through the plant. Generally, pass-through episodes will end when the treatment problem is solved. In this case, a proactive flushing program will not prevent the episode, but reactive flushing can help clear the problem. In addition, there is lower risk of co-occurring metals being released into the distribution system by a pass-through episode, unless significant chemistry changes were associated with a treatment upset. By comparison, release episodes are the result of chemical or physical changes in the distribution system, which disturb legacy Mn. Release episodes will continue until the chemical or physical changes are stopped, re-equilibration with legacy deposits is reached, or the deposit of legacy Mn is fully mobilized. During Mn release episodes, co-occurring metals associated with Mn could be released into the distribution system as well. Reactive flushing is an appropriate response, if the affected area is isolated and released materials are not inadvertently transported to unaffected areas of the system, and that legacy deposits are not “stirred up” without being removed from the system. Unlike pass-through episodes, a proactive UDF flushing program is useful since it can reduce the inventory of Mn in distribution system. However, it does not eliminate the risk of Mn release, nor is flushing capable of fully removing the inventory of legacy Mn from a distribution system. Often, more aggressive cleaning techniques such as ice pigging or foam swabbing are needed to remove more stubborn Mn-based deposits.

Classification of Mn Release Episodes

Utility experience illustrated that the extent of Mn release episodes can vary from isolated sections of the distribution system impacting few customers to large portions of the distribution system impacting many customers. In general, Mn release episodes attract little attention except from those who are impacted. On the other hand, if the episode involves a large number of customers, or highly visible customers, undesirable attention can be paid to a utility by the news media or public officials. Overall, Mn release episodes naturally fall into two categories: incidental release and event release.

Incidental Release

Incidental Mn release is localized and hard to distinguish from other colored water episodes or water quality problems. It generates little concern beyond impacted customers. Incidental release can be largely controlled by utilities through use of good distribution system operating and maintenance practices and its effects mitigated by maintaining good customer relations practices. These are practices that utilities should maintain whether they have a legacy Mn problem or not.

Event Release

Event Mn release is a large scale and intense colored water episode which results in widespread concern by customers. Generally, event release can be tied to major changes to distribution system hydraulics or chemistry. It necessitates coordinated reaction by a utility to clear released Mn from the system and restore customer confidence. In compiling this report, the project team found that utilities tended to have more information about their experience with event release than incidental release, probably because of the exceptional effort that the utility expended because of event release. The project team was able to document many of the impacts and costs associated with event releases, and

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©2015 Water Research Foundation. ALL RIGHTS RESERVED. demonstrated how widely costs can vary within and between systems. It was harder to determine costs associated with incidental release, since utilities generally did not segregate cost information directly related to legacy Mn.

Impacts of Mn Release Episode

While incidental Mn release may be of little impact to the day-to-day operation of a utility, an event release will have major and long-term consequences. Some of the impacts documented by the project resulting from event release include:

 Loss of customer confidence in the utility.  Potential for exposure of customer to regulated contaminants in excess of MCL.  Costs associated with customer complaint response program.  Costs associated with public relations program.  Costs associated with bottled water program.  Costs associated with payments for restitution for damages caused by colored water.  Costs associated with labor for reactive flushing.  Costs associated with development and implementation of a UDF program.  Water loss due to flushing.  Cost associated with water quality sampling and analysis.  Lost revenue due to reduced water sales.  Costs associated with consulting services.

A detailed review of these impacts is presented in Table 4.11 through Table 4.15.

Risk Factors for the Accumulation of Mn

While utilities cannot predict the exact amount of legacy Mn in their system, they can assess their risk factors of its occurrence. High risk factors include:

 Elevated source water Mn concentration (at present or in the past).  Ineffective Mn treatment (at present or in the past).  Use of Mn contaminated treatment chemicals (at present or in the past).  Evidence of accumulation through observation of pipes scale, tank walls etc.  Occurrence of distribution system colored water events not related to source water Mn levels.  Lack of flushing program or poorly designed flushing program.  Areas with large quantities of scale-forming pipe materials (such as unlined cast iron or galvanized pipe).

Utilities can refer to the utility self-assessment framework presented in Chapter 6 in order to systematically evaluate their risk for legacy Mn accumulation.

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Risk factors that increase the probability of the release of legacy Mn from scales and sediments within distribution systems include:

 Hydraulic disturbances such as changes in flow directions, sudden changes in demand, and pressure events.  Physical disturbances, such as major construction activities near distribution system mains.  Poor flushing practices that mobilized sediments but do not adequately remove them from the distribution system.  Chemical disturbances dues to changes in finished water chemistry or treatment (specifically lower pH and ORP) that promote soluble releases; changes in source waters or blending that may impact chemical stability.

Again, utilities can refer to the utility self-assessment framework presented in Chapter 6 in order to systematically evaluate their legacy Mn release risk.

Use of Existing Industry Best Management Practices to Control Legacy Mn

Utilities should consider undertaking best management practices that tend to minimize Mn accumulation and reduce the potential for release episodes. Many of these practices should be undertaken if the utility has a legacy Mn problem or not. As long as a utility has good treatment and distribution system operating and maintenance practices, the likelihood of significant release events should be minimized. As discussed in this report and in other industry guidance documents, there are a variety of best management practices utilities can implement on a system-specific basis with regard to main cleaning, source water and treatment optimization, and hydraulic and pressure management. With regard to legacy Mn accumulation and release, best practices should be use to achieve the following:

 Minimize Mn inventory in its distribution system.  Minimize sources of Mn entering the distribution system.  Minimize hydraulic disruptions and changes to water chemistry to stabilize legacy Mn present in distribution system scales and sediments.

Utilities can refer to example BMPs presented in Table 6.9 as goals to consider in the management of risk related to the presence of legacy Mn.

FUTURE RESEARCH NEEDS

The objectives of this project were to:

 Document the presence of legacy Mn in distribution systems.  Enumerate the potential impacts of legacy Mn on utilities.  Provide a framework for utilities to assess their risk associated with legacy Mn and develop a suitable response to their level of risk.

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©2015 Water Research Foundation. ALL RIGHTS RESERVED. While these project objectives were largely achieved, additional research will provide a more complete assessment of the impacts of legacy Mn on distribution system water quality and public health. Specific additional research needs include:

 Additional study of Mn occurrence and inventory in distribution system scales and sediments.  Additional study of individual contribution of Mn (vs. iron, sulfur, etc.) to biofilm growth.  Additional study of individual contribution of Mn to co-occurrence of regulated inorganics: o As a function of water chemistry. o As a function of pipe material.  The role of biofilm on trace inorganic contaminant partitioning and accumulation.  Demonstration of main cleaning techniques on Mn-based scales.  Impacts of changes in residual disinfectants.  Monitoring programs to demonstrate Mn release risk.  Locations, parameters, frequencies, sampling strategies.

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UTILITY SURVEY QUESTIONNAIRE

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Utility Data Request Package & Questionnaire: Water System Manganese History

INTRODUCTION

HDR Engineering, in association with Confluence Engineering Group, was selected by the Water Research Foundation (WaterRF) to perform the first comprehensive study centered on understanding the impacts of accumulated (legacy) manganese (Mn) in water systems. It is anticipated that most distribution systems contain some level of legacy manganese, even systems that are served by surface waters with very low background manganese concentrations and/or systems that installed Mn treatment at some point in the past. The purpose of this research project is to improve the understanding of the problems caused by Mn that has previously accumulated and is accumulating in water systems, as well as cost-effective options to remove Mn from distribution systems. The end result of this project will assist utilities in managing manganese accumulation and cut costs

Your Utility is one of 10 systems across the United States that agreed to participate in the project. This Data Request Package is intended to help obtain an understanding of current and historical system conditions, experiences, and data availability relevant to determination of impacts of Mn accumulation, and the costs and effectiveness of various control strategies. Your responses to this Data Request will be pooled with the other participating utilities.

Please note that we are not seeking to get all data at this point (although you are welcome to begin compiling what you have available). In some cases, we have “fill-in- the-blank” type questions. In most cases though, we are trying to understand what data or records you may have which can ultimately assist our analysis. Your detailed responses to these exploratory questions will help guide us in the right direction and streamline future efforts. Once we receive the responses from this package, we will perform one-on-one follow-up to explore the issues you identify here, seek clarifications, and obtain the more detailed data. Our goal is to make this process straightforward for you, while obtaining the information we need to complete the project.

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Please complete this Data Request Package either in the MS Word electronic file and return via e-mail (preferable format), or alternatively you can print a hard copy, fill in by hand, and return via postal service, FAX, or e-mail (scanned PDF file) to the following individual, who is your project contact:

Name Title Company Address City, state, ZIP Phone / Fax / email

This Data Request Package should take about 8 to 16 hours to complete, depending on the complexity of your system (recall that the Level 1 In-Kind commitment associated with data sharing is approximately 40 hours). If you should have any questions, feel free to contact your project contact listed above. We look forward to receiving your responses and truly appreciate your efforts to support this study.

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Utility Name: Click here to enter text.

Address: Click here to enter text.

Contact Name: Click here to enter text. Title: Click here to enter text.

Office Phone: Click here to enter text.

Mobile Phone: Click here to enter text.

Fax: Click here to enter text.

E-mail: Click here to enter text.

Best Time to Contact: Click here to enter text.

1.0 BACKGROUND INFORMATION This section tells us basic information about your utility.

1.1 General Background Information Please provide a brief description (1 or 2 paragraphs below) of your utility’s historical experience with manganese occurrence and legacy manganese issues, similar to the information you gave when introducing yourself during the kick-off webinar.

Click here to enter text.

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Estimated population served: Retail:

Wholesale:

Number of service connections: Retail:

Wholesale:

Classification Surface Water:

Groundwater:

GWUDI:

Mixed Supply: %GW %SW

What is your Average Daily Production? MGD*

What is your Maximum Daily Production? MGD

What is your Maximum Supply Capacity? MGD

Retail % *What fraction of average daily production is attributable to: Wholesale %

How many sources do you currently use on a regular basis?

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©2015 Water Research Foundation. ALL RIGHTS RESERVED. 2.0 TECHNICAL INFORMATION This section tells us information about your source water, treatment and distribution system. We are requesting the following information by Points of Entry (POE). Per the instructions below, we are asking that you fill out Table 2.1 only for POEs with a history of Mn occurrence (or you suspect to have a history of Mn occurrence) and for POEs that serve a specific zone of the distribution system with a history of Mn issues.

2.1 Information about Mn entering your system

Complete Table 2.1 for each current and former point-of-entry (POE) that meets either of the following criteria: It currently has or used to have measurable Mn in the treated water at some point during its operating life (going back as far as 20 years, to around 1990). It directly serves (or used to serve) a portion of your water system that was also served by other sources which do/did have measureable Mn.

Please complete one table for each relevant POE. Create additional copies as needed for each of your POEs meeting the above criteria. To complete the table, begin with the left-most column to record the current or most recent conditions for the POE. If there has been a major change in operation of the POE (e.g., change in source conditions, treatment process, treated water quality, production strategy, or other), record this information in the next column to the right. Provide the information for a 20-year timeframe from 1990 to 2010, working backward in time and adding columns if necessary to record the requested information.

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©2015 Water Research Foundation. ALL RIGHTS RESERVED. Table 2.1 – Information about Mn Entering Your System – Complete one for each POE Name/ID of Point-of-Entry (or Water Treatment Plant): Click here to enter text. Status: Currently Used Formerly Used, Discontinued in: Click here to enter a date. Parameter Most Recent Prior Condition Prior Condition

to Applicable Timeframe to to (last year) (first year) (last year) (first year) (last year) (first year) New source New source New source Source water changes Source water changes Source water changes New treatment facility New treatment facility New treatment facility Basis for this Timeframe Treatment upgrades Treatment upgrades Treatment upgrades i.e., what changed since the Change in Change in Change in previous timeframe? Production/Use Strategy Production/Use Strategy Production/Use Strategy (check all that apply) Discontinued use Discontinued use Discontinued use Other (describe below): Other (describe below): Other (describe below): Click here to enter text. Click here to enter text. Click here to enter text.

Description/Type of Raw Water Sources that Feed Click here to enter text. Click here to enter text. Click here to enter text. this POE/WTP

Narrative Description of Click here to enter text. Click here to enter text. Click here to enter text. Raw Water Quality Issues

Description of Treatment Train, inc. Unit Processes, Click here to enter text. Click here to enter text. Click here to enter text. Chemicals, and Purposes (attach schematic or PFD)

Yes No Yes No Yes No Is There a Specific Process Please describe: Please describe: Please describe: In‐Place for Treatment of Click here to enter text. Click here to enter text. Click here to enter text. Manganese (Mn)?

POE/WTP Capacity MGD MGD MGD Baseload Baseload Baseload For Peaking For Peaking For Peaking Description of Production/Use Strategy Seasonal () Seasonal () Seasonal () Other: Other: Other: Click here to enter text. Click here to enter text. Click here to enter text.

Name/ID of Zone Served Click here to enter text. Click here to enter text. Click here to enter text. Directly by this POE/WTP

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Name/ID of Zone(s) Served Click here to enter text. Click here to enter text. Click here to enter text. Indirectly by this POE/WTP

Win Average Production MGD % MGD % MGD % Trend by Season Spr MGD % MGD % MGD % (in MGD and as the % of supply to zone Sum MGD % MGD % MGD % served directly) Fall MGD % MGD % MGD % Average Mn Level at POE (in mg/L) Average Iron Level at POE (in mg/L) Do you have seasonal Mn Yes No Yes No Yes No data for this POE?

Average: mg/L Average: mg/L Average: mg/L Win Range: mg/L Range: mg/L Range: mg/L

Average: mg/L Average: mg/L Average: mg/L If available, please Spr summarize Mn Level Range: mg/L Range: mg/L Range: mg/L at POE by Season (in Average: mg/L Average: mg/L Average: mg/L mg/L) Sum Range: mg/L Range: mg/L Range: mg/L

Average: mg/L Average: mg/L Average: mg/L Fall Range: mg/L Range: mg/L Range: mg/L Other Water Quality Click here to enter text. Click here to enter text. Click here to enter text. Concerns for this POE (e.g., co‐occurring metals or radionuclides such as arsenic, iron, radium, uranium, chromium, TOC, etc.) Click here to enter text. Click here to enter text. Click here to enter text.

Please provide any other information about this POE that you feel would be important for us to know about.

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Yes No

If yes, please explain how recycle could occur and which POE’s are impacted: Click here to enter text.

2.2 Information about your retail distribution system

2.2.1 Provide information about your distribution system under current conditions:

Approximate miles of pipe

Number of pressure zones

Number of entry points (POEs)

Number of treated water storage reservoirs/ combined capacity (MG)

Residence time (days) Average/Max

Please attach a system schematic that shows sources of supply, points of entry, pressure zone boundaries/IDs, etc. If there is a particular pressure zone(s) or region(s) of the system that are more significantly impacted by legacy manganese, please circle, list, or describe. Schematic attached? Yes No

2.2.2 Is there a particular part of the retail distribution system (e.g., specific pressure zones or regions that is (or was) more vulnerable to Mn accumulation and/or release? This will be referred to as Mn-Specific Zones in questions 2.2.2.1 – 2.2.2.3. (Please respond for as many zones as necessary, attach copies for each zone, if needed)

Yes No

Please explain. Identify which POEs supply the Mn-specific zones. Click here to enter text.

2.2.2.1 Have you made major modification to your distribution system in the last 20 years such as added or combined pressure zones, major new expansion, began wheeling water, etc.?

System-Wide: Yes No

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Mn-Specific Zone(s): Yes No

Please explain: Click here to enter text.

2.2.2.2 If you indicated in Question 2.2.2 that you have Mn-Specific Zones, please estimate the current distribution system pipeline materials for each zone. If you do not have a Mn-Specific Zone, please estimate for your entire retail distribution system. Indicate which way you are responding: Mn-Specific System-Wide

Zone ID Unlined Cast iron % Unlined Ductile iron % Unlined Steel/Galvanized % Cement-lined % PVC/HDPE % Concrete/Transite (AC) % Other % (Specify: )

2.2.2.3 Any significant changes in pipe material breakdown over the past 20 years (both Mn- Zone specific and system-wide)?

Yes No

Please explain: Click here to enter text.

2.2.3 What type of disinfectant residual is used in your distribution system?

Chlorine Chloramine

mg/L – typical disinfectant residual at distribution system entry points mg/L - disinfectant residual at the end of distribution system mg/L - average disinfectant residual in the distribution system

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2.2.4 Has your primary or secondary disinfection scheme changed in the past 20 years?

Yes No

Please explain: Click here to enter text.

2.2.5 Do you have any strategy/procedure to maintain disinfectant residual in your distribution system? Yes No

Any changes in the past 20 years? Yes No

Please explain (strategy/procedure and change if any): Click here to enter text.

3.0 DATA AVAILABILITY This section helps us know what data and institutional knowledge you have that can assist us in understanding legacy Mn impacts.

3.1 Information that helps us understand Mn occurrence in your distribution system

3.1.1 Do you monitor for the water quality parameters shown in Table 3.1 within your distribution system? Please complete the table and indicate the range of years for which data is available for each type of monitoring. The Project Team will use this information to determine what data we will request at a later time.

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Response to Response to During Other? Type of Additional Routine Monitoring Customer Colored Maintenance Monitoring Comments Complaints Water Events or Flushing? Please Describe

# of Parameter Yes/No Frequency Locations Yes/No Yes/No Yes/No Dissolved Yes

Manganese No Yes Yes Yes Click here to Click here to Click here to enter a date. To Click here to enter a date. No No No Years of data enter text. enter text. available: Total Yes

Manganese No Yes Yes Yes Click here to Click here to Click here to enter a date. To Click here to enter a date. No No No enter text. enter text. Years of data available: Dissolved Iron Yes No Yes Yes Yes Click here to Click here to Years of data Click here to enter a date. To Click here to enter a date. No No No enter text. enter text. available: Total Iron Yes

No Yes Yes Yes Click here to Click here to Years of data Click here to enter a date. To Click here to enter a date. No No No enter text. enter text. available: Yes Other No Regulated Yes Yes Yes Click here to Click here to Click here to enter a date. To Click here to enter a date. Metals Years of No No No enter text. enter text. data available:

pH Yes Click here to Click here to

No Yes Yes Yes enter text. enter text. Years of data Click here to enter a date. To Click here to enter a date. No No No available:

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©2015 Water Research Foundation. ALL RIGHTS RESERVED. Yes Click here to Click here to TDS No Yes Yes Yes enter text. enter text. Years of data Click here to enter a date. To Click here to enter a date. No No No available: Yes Click here to Click here to Alkalinity No Yes Yes Yes enter text. enter text. Click here to enter a date. To Click here to enter a date. Years of data No No No available: Yes Click here to Click here to Hardness No Yes Yes Yes enter text. enter text. Years of data Click here to enter a date. To Click here to enter a date. No No No available: Yes Click here to Click here to Nitrate/Nitrite No Yes Yes Yes enter text. enter text. Years of data Click here to enter a date. To Click here to enter a date. No No No available: ORP (Redox Yes Click here to Click here to

Potential) No Yes Yes Yes enter text. enter text. Click here to enter a date. To Click here to enter a date. No No No Years of data available: Yes Click here to Click here to Turbidity No Yes Yes Yes enter text. enter text. Years of data Click here to enter a date. To Click here to enter a date. No No No available: Yes Click here to Click here to Color No Yes Yes Yes enter text. enter text. Years of data Click here to enter a date. To Click here to enter a date. No No No available:

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3.1.2 In what format are your water quality data available? Hard Copy Electronic

3.1.3 Do you maintain a history or database of customer complaints?

Yes No Dating as far back as: Click here to enter a date. Data format? Hard Copy Electronic

3.1.4 Does your utility take water quality samples when responding to customer complaints? Yes No

If yes, what analyses are performed? (indicate if they are field or lab-based techniques) Click here to enter text.

3.1.5 On average, approximately how many discolored water events do you experience under current conditions?

#/year – System-Wide #/year – Mn-specific zones

3.1.6 Are you able to differentiate between manganese and iron (or other suspended solids/ metals) as the primary cause of the discolored water events?

Yes No Combined

Please explain: Click here to enter text.

3.1.7 Do you have a response plan for colored water events?

Yes No

If yes, please briefly explain what that plan entails and who is involved: Click here to enter text.

3.1.8 Is there a seasonal component to the frequency of colored water events?

Yes No

If yes, what is the % of discolored water occurrences by season? Please fill in table. Winter Spring Summer Fall Overall Jan - Mar Apr - Jun Jul - Sept Oct - Dec

100%

3.1.9 Does your utility have an established flushing program?

Yes No

Please describe and address the following issues: Is program reactive or proactive (or both)? Unidirectional (UDF) or conventional? What velocities are targeted? Is it system- wide or focused in the Mn-Specific Zone(s)? What are typical miles per year (or % of system per year)? Click here to enter text.

3.1.10 Does your utility collect and analyze samples from flushed water?

Yes No

If yes, what analyses are performed? Click here to enter text.

3.1.11 Has your utility conducted pigging/cubing/swabbing or other techniques to remove solids from system piping?

Yes No

If yes, please describe: Click here to enter text.

3.1.12 Has your utility performed any special studies focused on Mn accumulation or impacts?

Yes No

If yes, please describe: Click here to enter text.

3.1.13 What actions does your utility take to control Mn build-up in the distribution system? Click here to enter text.

3.2 Information that helps us understand potential cost-incurring impacts related to Mn in your distribution system.

Your responses to each of these questions may change depending on how your treatment program and system operations have changed over the past 20 years. Please indicate, where possible, the time period that is relevant to the information you provide.

3.2.1 Does your utility track hours spent dealing with customer complaints?

Yes No

3.2.2 Does your utility track the number of Mn samples or other water quality samples taken to monitor for or respond to Mn or colored water events in the distribution system?

Yes No

3.2.3 Does your utility have an on-going distribution system pipe replacement program?

Yes No

If yes, what annual percentage is due to Mn accumulation? Click here to enter text.

If yes, what is the estimated average annual cost of pipe replacement due to Mn accumulation? Click here to enter text.

3.2.4 Has your utility ever had to pay damages or make restitution to customers because of Mn staining or other impacts caused by Mn release?

Yes No

If yes, please describe the event(s) and circumstances.

Click here to enter text.

3.2.5 Has your utility ever had enter into a public relations campaign because of Mn or colored water/release events?

Yes No

If yes, please describe the event(s) and circumstances.

Click here to enter text.

3.2.6 Has your utility experienced equipment “fouling” issues within the distribution system (from POE thru customer service connections) due to manganese accumulation? Consider impacts to meters, valves, pumps, other. Fouling could be impaired performance, accelerated wear-and-tear, other.

Yes No

If yes, please describe:

Click here to enter text.

If yes, indicate below where costs have been incurred to resolve “fouling” issues:

O&M staff time Contractor Equipment Replacement

3.2.7 Please describe any other time or cost-incurring impacts that your utility has experienced that may be associated with Mn accumulation/release in your distribution system.

Click here to enter text.

3.3 Information that helps us understand non-cost impacts related to Mn in your distribution system

3.3.1 Has your utility ever received publicity in the media because of a Mn release or colored water event?

Yes No

If yes, please describe: Click here to enter text.

3.3.2 Has your utility lost customers because of a Mn or colored water event?

Yes No

If yes, please describe: Click here to enter text.

3.3.3 Has your utility had to disrupt service because of a Mn or colored water event?

Yes No

If yes, please describe: Click here to enter text.

3.3.4 Has your utility ever abandoned a source (or restricted/constrained source usage), or abandoned portions of your infrastructure, due to the presence of Mn?

Yes No

If yes, please describe: Click here to enter text.

3.3.5 Have your system experienced other water quality impacts due to the presence of Mn. Example: difficulty maintaining disinfectant residual, growth of Fe/Mn bacteria, coliform occurrence, other?

Yes No

If yes, please describe: Click here to enter text.

3.3.6 Please describe any regulatory compliance issues that you have experienced due to legacy Mn in your distribution system. Click here to enter text.

3.3.7 Please describe any other known customer-related impacts associated with Mn build-up release events, as they relate to customer confidence, perception of safety/value, etc. Click here to enter text.

4.0 OTHER ITEMS This sections lets you tell us what we have missed.

4.1 Information you might have that we didn’t ask for

4.1.1 Is there information you have that we didn’t ask for but you think would be helpful to share with the project? Please describe: Click here to enter text.

4.2 Information or issues concerning Mn that you consider important that we may have not asked.

4.2.1 Are there concerns or issues that you have pertaining to legacy Mn that we have not asked about? Click here to enter text.

4.3 Estimated time to complete this form.

4.3.1 Estimate the total amount of time that you and your staff needed to complete this form: hours

The Mn Accumulation Project Team appreciates your time and your valuable input to the project! We will review your submittal and follow up individually as appropriate.

APPENDIX B

SUMMARY OF SURVEY RESULTS

Question Arvada Boulder Lacey 1.1 Self- Experienced Mn related colored Mn historically released from Mostly groundwater-supplied system that utilizes 19 wells. Untreated described water event in 09/2007. Problem sediments in Boulder Reservoir sources with dissolved Mn (and Fe) started to be used ~1979. experience from the AWTP (used May under anoxic conditions in summer Complaints related to staining, taste and odor were localized, but were with Mn through September). Survey months resulting in customer most common in the vicinity of the source with the highest answers are for the area served by complaints of discolored water and concentrations of Mn and Fe (~0.4 mg/L Mn, 0.4 mg/L Fe) and in the AWTP that had the Mn event. staining plumbing fixtures. In 2001 dead end/high water age areas that received that source water. At the To complicate the analysis / the plant intake was modified to time, Lacey was an unchlorinated system, and the city would get conclusions water from the RWTP enable avoiding anoxic water at the localized colored water complaints when chlorinated water from the is mixed with water from the bottom of the reservoir. Problems intertie with the city of Olympia was used for peaking. AWTP. Following the 09/2007 abated until this year when use of Iron and sulfur bacteria accumulated both in the distribution system event, some water was blended reservoir increased. and in customer's home plumbing. Brown water episodes and from the 4-3 valve at the Arvada associated complaints gradually started to become more frequent in Plant. The water chemistry leaving the late 1990s, then by 2002-2003 they were widespread, frequent, the two water treatment plants were and customers that had experienced several episodes were angry. At matched, but the City still uses the the time, response to most episodes was spot-flushing although this two separate entry points into the often resulted in more complaints. The frequency of brown water distribution system. Water from the events and the need to maximize use of existing sources finally RWTP separately feeds part of the convinced management to invest in programs to improve water one area that had a Mn problem. quality. Since then Lacey has constructed two Mn/Fe treatment Areas that were served only by the plants, started a UDF program, started chlorinating the water system, RWTP have not had a Mn related and inactivated one intertie source with dissolved Mn. Complaints problem. related to Mn/Fe staining and brown water are now rare although we still have one untreated source that contains Mn. Most manganese from that source is oxidized by chlorine and drops out into the distribution lines, so to address this that area is flushed annually.

(continued)

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Question Moscow Newport Newport News 1.1 Self- Receives water supply from five wells. These wells are Newport has 2 surface water reservoirs that Newport News Waterworks operates two described located in the Columbia Basalts, two in the shallow combine into one. The upper reservoir feeds surface water plants (Harwood's Mill and Lee experience aquifer, which is the Wanapum, and three in the deeper water to the lower reservoir to maintain a Hall) and one brackish groundwater system, with Mn aquifer, which is the Grande Ronde. The shallow aquifer constant level. Pump water from the lower which feed into a single, common ranges from 240 to 500 feet deep and the deeper aquifer is reservoir. Currently, pump off of the bottom distribution system. Waterworks has about 1300 feet deep. Most of the wells drilled in of the reservoir. When we go through the seasonal high levels of Mn, which have been Moscow are high in Fe and Mn with the exception of one transition from spring to summer our raw exacerbated by recycle streams at both well which has very low levels. water warm-up and there is stratification plants. The issue has been complicated by the The first wells drilled in Moscow were in the shallower issues. When that happens, there is a loss in use of ozone disinfection at both plants and aquifer with high levels of Fe and Mn that was not the dissolved oxygen that was in the raw water biofiltration at Lee Hall. filtered and the residence of Moscow in the 1920’s and the concentration of Mn increases. When through late 1970’s were accustomed to water from the this occurs we start feeding NaMnO4. The tap that was yellow or dirty water cause by sediments that distribution system has accumulated Mn on accumulated in the City water mains. the walls of the pipe from not using an oxidizer in the past. When a volume of water The City of Moscow in the 1950’s began to drill into the is used in the distribution system (i.e. broken deeper aquifer which provided some relief from yellow pipe, fire, etc.) we can receive call from water however filtration was added in the 1970’s which customer that have dirty water. We do not removed most of the Fe and Mn in the two shallow wells. currently have a flushing program in place. Still today, the customers of the Moscow Water Department continue to experience yellow water or dirty water from the sediments, which do occur from the few deeper aquifer wells that are not filtered. All of Moscow’s wells pump directly into the distribution system and for this reason they have been combined into POE.

(continued)

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Question Report Philadelphia Park City Renton United Water 1.1 Self- PWD does not have documented In 2007 and again in 2010 we In 1990, the City of Renton drilled At United Water Idaho (UWID), Boise’s described historical experience with legacy Mn experienced discolored water in our three wells averaging around 400 feet source of supply, there is a combination experience occurrence problems in the system in the Thaynyes Zone. In deep on the City's golf course in of surface and ground water. with Mn distribution system. PWD does have 2007 the lab test showed the Arsenic, Maple valley. The wells remained Approximately 70% of the water is Mn in its source (surface) waters but Antimony, Thallium and Mn high unused until 1994 until the treatment supplied from 76 wells located the Mn is removed via an induced levels. We did a complete plant was built. Pilot testing was throughout the Boise area. The oxide-coated media effect upon unidirectional flushing of this zone performed on the wells by the city remaining 30% of the water comes from filtration following the addition of free every day for 8 days before it cleared personnel. It was found that the water two surface water treatment plants chlorine. We maintain a database of up. In 2010 when it happened again had some Fe, Mn, and hydrogen (Marden Water Treatment Plant and customer complaints. A part of our we sample right away and again found sulfide in the water. The treatment Columbia Water Treatment Plant), which protocol when analyzing routine, daily that the Arsenic, Antimony, Thallium plant was built with sequestering Fe both treat water from the Boise River. distribution samples (total coliform and Mn were high. We did a and Mn with Aqua Mag, a Groundwater from our wells is treated rule samples) for general water quality complete unidirectional flushing of polyphosphate blend. The Hydrogen with small amounts of chlorine to protect is to further analyze any sample with this zone. The arsenic and antimony sulfide would have to be removed by against potentially hazardous turbidity > 1 NTU for Fe and Mn, so were the first to go back down to lowing the pH from 7.8 to 5.6 with microorganisms that can get into the there is available a dataset of normal levels. Mn was the next sulfuric acid and then air stripped by water. We strive to maintain an average distribution system Mn results in (about two weeks) with thallium being using a pack tower and blowers to chlorine residual between 0.2 and 0.8 samples with elevated turbidity that the last to come down under the MCL. strip away the hydrogen sulfide. The ppm throughout the distribution system. could be compared to historical entry- This event took us about a month to sequestering did not work very well We also add very low doses of to-distribution results. We also clear up. One thing to note during this and customers were complaining polyphosphate at 14 of our wells to sampled our system at near, mid and event after about a week of flushing about dishwashers becoming grey and isolate Fe and Mn and keep the water far (relative to the treatment plant we picked up trace amounts of white laundry having black spots on clear. locations) points in the system as part Mercury in samples that we took for them. In 2002, HDR did a pilot test to Historically, UWID has always battled of WRF project number 2863 and three days. We sampled every day. design a Fe and Mn removal treatment Fe and Mn from some of our ground analyzed for total, dissolved and facility. Water usage from the deep water sources. At three of our wells, we "truly" dissolved (passing through a wells was stopped and the treatment have constructed Green Sand Treatment 30kDa ultra filter) fractions of Mn. plant was completed in 2005 and has Facilities recently to remove both Fe and been running since then. Mn. We still treat the iron and Mn at 14 wells with phosphate.

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Question Topic Arvada Boulder Lacey Moscow Newport 1.2 Population Served 105,000 166,000 67,175 24,500 9,950 1.2 Average Production 7.45*/15.97 15.4 7.02 2.17 2.5 1.2 Retail/Wholesale 98/2 98/2 100/0 100/0 100/0 1.2 Service Connections 34,000 28,392 21,815 5,700 1.2 Water Type Surface Surface Mixed Supply Ground-water Surface 1.2 Number Sources 3 4 19 5 1 Number of POEs 2 2 16 4 1 T&O, sulfate, Seasonal high TOC, T&O, Table 2.1 Treatment Concerns T&O Detectable Mn at times High Fe and Mn hardness Fe, Mn Other Water Quality Table 2.1 MIB / Geosmin TOC None Only Fe TOC Concerns DAF, Conventional (did not provide Did not provide description / shallow aquifer wells / green Did not provide description / Table 2.1 Treatment Process conventional description / schematics) schematics sand filters schematics filtration Manganese specific Table 2.1 No No No Yes Yes treatment Primary Disinfectant Cl2 Cl2 Cl2 Cl2 Cl2 2.2.3 Residual Disinfectant Cl2 Cl2 Cl2 Cl2 Cl2 Distribution system size 2.2.1 531 456 357 93.3 73 (miles pipe)

2.2.1 Number Pressure Zones 5 at time of study 3 7 5 3

~36% Cement- Lined Cast Iron, Cement lined/ Cement lined cast and ductile 2.2.2.2 Predominant pipe material 49% PVC ~30% Cement PVC/ Did not provide iron Lined Ductile HDPE/AC Iron, ~22% PVC 3.1.9 Flushing program UDF Yes Yes/UDF Yes No 3.1.11 Pigging program No No No No No DS Pipe Replacement 3.2.3 Yes Yes Yes Yes No Program Table 2.1 Change in Source No No No No No Table 2.1 Change in Treatment No Yes No No No 2.2.4 Change in Residual No Yes Yes No No Change in Distribution 2.2.2.1 No No Yes No Did not answer System Configuration Change in Distribution 2.2.2.3 No No Yes No Did not answer System Pipe Material 1. Data provided above reflects utility survey responses that were completed in 2011. (continued)

149

Question Topic Newport News Philadelphia Park City Renton United Water 1.2 Population Served 415,000 1,526,006 7,500 86,230 245,000 1.2 Average Production 34 244.5 4 6.7 38,399 1.2 Retail/Wholesale 100/0 92/8 100/0 90/10 100/0 1.2 Service Connections 130,000 475,371 4,500 17,368 85,127 Ground- 1.2 Water Type Mixed Supply Surface Ground-water Mixed Supply water/GWUDI 1.2 Number Sources 3 2 7 6 78 Number of POEs 2 3 7 1 78 Periodic high Mn High in Fe, Arsenic, Table 2.1 Treatment Concerns None None High Fe & Ammonia levels and Mn Ammonia, Hydrogen Table 2.1 Other Water Quality Concerns None None Arsenic Iron Ammonia Sulfide, Iron air induction, GAC Conventional Sodium contactors, pre Cl 2 Loprest Green Sand Treatment Table 2.1 Treatment Process treatment with Conventional Hypochloride and injection, green sand System intermediate ozone Ferric chloride filters, post Cl2, contact chamber Table 2.1 Manganese specific treatment Yes Yes No Yes yes Primary Disinfectant Cl2 Cl2 Cl2 Cl2 Cl2 2.2.3 Residual Disinfectant Chloramine Chloramine Cl2 Cl2 Cl2 Distribution system size (miles 2.2.1 1,743 3,145 80-100 305 1,195 pipe)

2.2.1 Number Pressure Zones 2 11 48 13 10

Unlined Cast Iron/ Unlined Ductile Unlined Cast Iron/ Unlined Ductile Iron Unlined Iron/ Unlined Steel/ Unlined cast Steel/ 2.2.2.2 Predominant pipe material Cement-lined/PVC/ Unlined Cast Iron/ Galvanized/Cement- iron PVC/ HDPE/ lined/PVC/HDPE HDPE/ AC AC Yes/ Yes/for 3.1.9 Flushing program Yes No Yes reactive residual 3.1.11 Pigging program No No No No Yes 3.2.3 DS Pipe Replacement Program Yes Yes Yes Yes Yes Table 2.1 Change in Source No No No No No Table 2.1 Change in Treatment Yes No Yes Yes Yes 2.2.4 Change in Residual Yes No Yes Yes No Change in Distribution System 2.2.2.1 No No Yes Yes Yes Configuration Change in Distribution System Did not 2.2.2.3 No No Did not answer No Pipe Material answer

Question Characteristic Arvada Boulder Lacey Moscow Newport 3.1.5 Frequency of colored water <1 - 4 50? Did not answer events 3.1.8 Seasonal impacts Did not answer Yes No Yes Yes

2.2.2 Specific zones Mn impacted Yes Yes Yes No Did not answer

3.1.7 Colored Water Response Plan Yes No Yes Yes Did not answer

3.1.13 Take actions to control Mn Flushing Control at POE Flushing Flushing Did not answer buildup 3.2.5 PR Campaign No No No No No 3.2.6 Any fouling of equipment No No Yes No No 3.3.6 Mn caused compliance issues None None None None Did not answer 3.3.5 WQ impact due to Mn No No Yes Yes No 3.3.7 Other Mn caused issues widespread None Dissatisfaction Expect better quality Did not answer dissatisfaction 3.2.7 Other impacts Customer None Colored water Flushing Did not answer response time 3.3.1 Adverse Mn Publicity No No No No No 3.2.4 Paid damages for Mn No No Yes Yes Did not answer 3.3.2 Lost customers No No No No No 3.3.3 Stop service due to Mn No No Yes No No 3.3.4 Abandoned source No Yes Yes No No 3.1.12 Performed Mn Specific Study Yes No No No Yes

(continued)

Question Characteristic Newport News Philadelphia Park City Renton United Water 3.1.5 Frequency of colored water 5 None for Mn 1 0-3 45 events 3.1.8 Seasonal impacts No No No No No 2.2.2 Specific zones Mn impacted Yes No Yes Yes Yes 3.1.7 Colored Water Response Plan Yes No Yes No Yes 3.1.13 Take actions to Minimize Mn Removal in control Mn Flushing None Flushing concentration treatment buildup 3.2.5 PR Campaign No No Yes No No 3.2.6 Any fouling of No No No No No equipment 3.3.6 Mn caused two events above the compliance None None MCL on a couple of Did not answer None issues metals 3.3.5 WQ impact due No No No No No to Mn 3.3.7 Other Mn Treat swimming None known Did not answer Did not answer None caused issues pool 3.2.7 Other impacts giving away of vitamin C to Green Sand Did not answer Did not answer Very expensive remove Mn Treatment staining 3.3.1 Adverse Mn Yes No Yes No No Publicity 3.2.4 Paid damages No No No Yes Yes for Mn 3.3.2 Lost customers No No No No No 3.3.3 Stop service No No Yes No Yes due to Mn 3.3.4 Abandoned No No No Yes No source 3.1.12 Performed Mn No Yes Yes No No Specific Study

Newport United Park City Question Characteristic Arvada Boulder Lacey Moscow Newport News Philadelphia Renton Water 3.1.3 Data base of customer Yes Yes Yes Yes Yes Yes Yes No No Yes complaints 3.1.4 Sample water quality in Yes No Yes Yes Yes Yes Yes No No Yes response 3.1.10 Water quality Did not Yes No Yes No No Yes No No Yes during flushing answer 3.2.1 Complaint Yes No Yes Yes Yes Yes No No Yes Yes hours 3.2.2 Number of Yes No No No No No No Yes No No samples taken 3.1.10 Take flushing Did not Yes, but not for Yes No Yes No No No No Yes samples answer Mn

APPENDIX C

SURVEY FOLLOW-UP TOOL

Tailored Utility Data Follow-Up

 Identify whether analysis and data collection needs should be system‐wide or just for Mn‐affected zones. 1. Does use of Mn‐specific zones make sense? Consider response to Q 2.2.2. Are there multiple sources with large Mn differences? Do Mn‐affected zones represent < 80% of overall system (in terms of pipe miles, no. customers)? 2. Is it practically feasible? Can utility data (on # of complaints, miles flushed, etc.) be screened or estimated for just those zones?

 If "YES" to both (1) and (2), then response to all questions should be specific to Mn‐affected zones. Otherwise, perform system‐wide analysis. If Mn‐specific, obtain an estimate of the population served (Q 2.1), ERUs, and miles of pipe (Q 2.2.1) that are specific to Mn‐affected zone.

 Based on the selected portion of DS, review the historical 20‐year timeline of system conditions per Section 2 (emphasis on POE conditions per Table 2.1). Define key time intervals where system/POE conditions and risk factors changed significantly (e.g., source/treatment change affecting Mn loading, flushing program start, etc.). Create a visual storybook/spectrum to denote key intervals. Example below:

 Data collection strategy: We'll take whatever they have or can reliably estimate (see tabs for strategies to estimate). Attempt to obtain data for each "key interval" if possible. For large or significant time intervals where data is not available, attempt to estimate. With the data that is provided, identify the associated years/key interval to which it corresponds.

The following represent the key "threads" for which data needs to be obtained or estimated:

 Pipe Flushing/Cleaning Which techniques are used No. of miles of pipe (or % of system) flushed/cleaned per year (average) or total over a specified timeframe By cleaning technique Preventative vs. Reactive Staff Labor hours (total per year on average, or average person‐hours per mile) Lab/analytical costs Other costs (equipment, contractor, consultant)

 Customer Complaint Handling No. of Mn‐related customer complaints per year (average) or total over a specified timeframe Staff Labor hours (total per year on average, or average person‐hours per complaint). Lab/analytical costs Other costs

Indirect Impacts Specific Data Needs Key Clarifications and Follow-Up Discussion Notes

Customer Complaints Q 3.1.3 Obtain historical # of complaints per year, filtered for Mn-specific "Filter" the complaint database for WQ-related issues (as opposed to other Related to Mn/Colored issues as feasible (see right for criteria). types of complaints). Determine if WQ complaints are filterable for specific Water issues such as: discoloration (see Q 3.1.6 below), staining, metallic T&O.

Q 3.1.6 If utility can differentiate between Fe and Mn, qualify the response to Q 3.1.3 and Q 3.1.5 to include Mn-only complaints/events.

Q 3.1.5 Clarify utility interpretation of question, i.e., were "discolored water If events were discrete groups, attempt to estimate an average # of events" considered individual complaints, or discrete groups of complaints per event. complaints related to a specific cause?

Q 3.1.5 Identify whether the events/complaints are generally "pass-thru" Consider presence/lack of POE treatment for Mn, and seasonality of event vs. accum/release (consider treatment and seasonality). occurrence (Q 3.1.8), to determine if "pass-thru" or accum/release.

Service Disruptions Q 3.3.3 How many events/customers affected? (define the timeframe). If possible, obtain or estimate the effort/costs incurred for a "typical" disruption Related to Mn/Colored Typically how long did they last? For what specific reasons event (e.g., utility staff time for notification, source or service isolation, dealing Water (related to Mn)? with questions, etc.)

Customer Q 3.3.1 Elaborate on questionnaire response. Was the media coverage Were there additional customer inquiries/feedback due to the media Feedback/Impacts to "responsible", i.e., thorough, fact-based? Was the utility contacted attention? What was their nature? Customer Confidence or involved in the development of the media report?

Q 3.1.7 Identify aspects of response plan related to customer interaction. Identify customer feedback to utility response measures intended to control the issue.

Q 3.3.7 Elaborate on questionnaire response. Describe any direct customer pressure/feedback to improve Mn control?

Direct Impacts Specific Data Needs Key Clarifications and Follow-Up Discussion Notes

Utility Labor Effort for Q 3.2.1 Specific to Mn/colored water complaint response, provide: Identify what activities are included in the hours figures to be provided (see Q Complaint Response average # of staff-hours per year or total over a given timeframe. If 3.1.7), e.g., travel, on-site investigation, lab coordination, sampling, on-site not available, estimate the average/typical total # of staff-hours per spot flushing, customer follow-up, databasing, etc. Exclude time associated complaint. with broader reactive flushing (to be included in Topic Area #3).

Monitoring/Analytical Q 3.1.4 Specific to Mn/colored water complaint response, confirm which See Table 3-1 for monitoring activities performed during complaint Costs for Complaint analytes are monitored and avg. # samples per event. Estimate response/colored water events. Exclude monitoring associated with routine Response unit cost for each ($/test) and note if internal/field or by commercial DS surveillance and flushing (these are covered elsewhere). lab.

Other Costs for Complaint Indicate other costs associated with complaint response. Response

Customer Restitution and Q 3.2.4 Document restitution occurrences - what were the impacts? what To extent possible, break-out the costs. Public Relations Efforts was the "scale" (average # of customers impacted)? Obtain or estimate the cost impacts to utility.

Q 3.2.5 Document nature of PR activities. Obtain or estimate associated To extent possible, break-out the costs. cost impacts to perform the PR campaign.

Lost Customers or Q 3.3.2 Document data. How many? What type of customers? Have any industrial/commercial customers switched water supply due to Mn Revenue issues? If so, estimate of lost water sales ($/year). Have any "large" customers installed POE Mn treatment?

Topic Area #2 - Co-Occurring Water Quality Issues

Indirect Impacts Specific Data Needs Key Clarifications and Follow-Up Discussion Notes

Regulatory - Other WQ Q 3.3.5 Q Elaborate on response. Identify any issues associated with Differentiate between "no impact" vs. "unaware of possible DS impacts/not Issues 3.3.6 coliform, Fe/Mn bacteria, chlorine residual maintenance issues, monitored for". etc. that are associated with Mn presence.

Regulatory - Q 3.3.6 Obtain metals data - in DS per Table 3.1, and associated "POE Refer to Table 3.1 for "other metals/parameters" monitored in the DS. Concentrations of Other Tables Concerns" per Table 2.1. Obtain metals data from any special Differentiate between "no impact" vs. "unaware of possible DS impacts/not Metals 2.1/3.1 studies (Q 3.1.12) or flushing looking at metals accum/release in monitored for". DS. Identify MCL/SMCL issues in DS.

Direct Impacts Specific Data Needs Key Clarifications and Follow-Up Discussion Notes

Utility Labor Effort for Q 3.2.2 Provide or estimate historical # of labor hours per year associated Use Table 3-1 to estimate no. of events/year. Monitoring Other Metals with DS monitoring of "other metals". If not available, estimate the average/typical "# of hours per event".

Monitoring/Analytical Q 3.2.2 Confirm which analytes are monitored and whether internal or by Direct Costs for Other commercial lab. Provide or estimate the annual total number of Metals samples of each "other metal" collected from the DS, or annual cost.

Topic Area #3 - Response to Mn Accum/Release

Indirect Impacts Specific Data Needs Key Clarifications and Follow-Up Discussion Notes

Areas of DS Vulnerable to Q 2.2.2 Confirm response. Obtain IDs of the zones of DS that are/were "Mn-affected" and identify the Mn Accum/Release POEs that serve them. Cross-reference with Table 2.1 to ensure POEs are accounted for.

Pipe Materials of Q 2.2.2.2 Confirm response. Vulnerable Areas

Actions to Respond to Mn Q 3.1.7 Confirm general response/reactive approach. Confirm specific techniques used: conventional flushing, UDF, swabbing, Releases Q 3.1.9 other. If UDF, what is velocity target? Q 3.1.11 Q 3.1.13

Direct Impacts Specific Data Needs Key Clarifications and Follow-Up Discussion Notes

Utility Labor Effort for Q 3.1.9 Specific to reactive flushing of DS (not individual services): Other approaches: (1) Estimate the average/typical # of pipe-miles flushed Response DS Cleaning Estimate average # of labor hours per year or total over a given reactively per response event. (2) Provide the annual total # of pipe-miles and Monitoring timeframe (by staff classification if possible). flushed (or labor hours spent flushing) and estimate the % that is reactive. Identify and estimate other costs (e.g., materials, equipment, contractor/consultant support) per year or per cleaning event. Identify # of staff that are typically involved in response flushing. Q 3.1.11 Specific to other reactive mains cleaning techniques (if relevant): Other approaches: (1) Estimate the average/typical # of pipe-miles cleaned Estimate average # of labor hours per year or total over a given reactively per response event. (2) Provide the annual total # of pipe-miles timeframe (by staff classification if possible). cleaned (or labor hours spent cleaning) and estimate the % that is reactive. Identify and estimate other costs (e.g., materials, equipment, contractor/consultant support) per year or per cleaning event. Identify # of staff that are typically involved in (non-flushing) response

Monitoring/Analytical Table 3.1 Specific to reactive mains cleaning practices: See Table 3-1 for monitoring activities performed during flushing. Exclude Costs for DS Response Q 3.1.10 Confirm/estimate # of samples per year, whether internal or by monitoring associated with routine DS and individual complaints (these are Q 3.2.2 commercial lab, and estimate the annual cost. covered elsewhere).

Equipment Fouling, Q 3.2.6 Identify relevant issues and associated cost impacts. Discuss Scope of question is POE thru customer connection (note: customer-side Cleaning, Replacement utilities interpretation of "fouling" for this question, e.g., impaired issues to be addressed under TA #1). Consider typical cost per event, # performance, condition that drives an O&M event, other? events per year, and frequency between events. Obtain costs for utility labor, equipment, contractor, etc.

Other Cost-Incurring Q 3.2.7 Identify impacts and relevant costs or labor effort. Determine if due Impacts Q 3.1.12 to accumulation of Mn (its actual presence) or release of Mn.

Topic Area #4 - Prevention of Mn Accum/Release

Indirect Impacts Specific Data Needs Key Clarifications and Follow-Up Discussion Notes

Actions to Control Mn Q 3.1.9 Confirm general approach for preventative control of Mn build-up. Confirm specific techniques used: routine DS monitoring (Table 3.1), Build-Up Q 3.1.11 conventional flushing, UDF, swabbing, other. If UDF, what is velocity target? Q 3.1.13

Extent/Frequency by Q 3.1.9 For each preventative Mn control technique used per above, For one-time events, indicate # of pipe miles cleaned by technique. Technique provide/estimate the # of pipe miles (or % of system) cleaned preventatively per year (or total # of pipe miles over a given timeframe).

Effectiveness by Identify observations about "Mn Removal Effectivness from DS", Consider: discharge WQ/color during cleaning techniques (e.g., peak Mn Technique including: comparison between different techniques, impact of levels, time to clear), colored water complaint trends after cleaning events, using different flushing velocities or techniques (UDF vs opportunities to visually see the pipe surfaces after cleaning, etc. conventional), relative effectiveness over time.

Direct Impacts Specific Data Needs Key Clarifications and Follow-Up Discussion Notes

Utility Labor Effort for Q 3.1.9 Specific to preventative flushing of DS pipes: If hours are not available, we can estimate based on answer to question Preventative DS Cleaning Estimate average # of labor hours per year or total over a given above about # of pipe miles flushed preventatively per year, if utility can timeframe (by staff classification if possible). identify # of FTE involved and % of time dedicated to preventative flushing.

Q 3.1.11 Specific to other preventative pipe cleaning practices: If hours are not available, we can estimate based on answer to question Estimate average # of labor hours per year or total over a given above about # of pipe miles flushed preventatively per year, if utility can timeframe (by staff classification if possible). identify # of FTE involved nd % of time dedicated to preventative cleaning.

Other Direct Costs for Identify and estimate other costs (e.g., materials, equipment, Preventative DS Cleaning contractor/consultant support). Use either total cost over a given timeframe or average per year.

Utility Labor Effort for Table 3.1 For routine DS monitoring associated with Mn, estimate labor Routine DS Monitoring hours per monitoring event or per year, per figures in Table 3.1.

Monitoring/Analytical Table 3.1 Specific to preventative DS pipe cleaning techniques: See Table 3-1 for monitoring activities performed during flushing. Costs Q 3.1.10 Confirm/estimate # of samples per year, whether internal or by Q 3.2.2 commercial lab, and estimate the annual cost.

Table 3.1 Specific to routine DS surveillance monitoring of Mn: See Table 3-1 for routine DS monitoring activities. Q 3.1.10 Confirm/estimate # of samples per year, whether internal or by Q 3.2.2 commercial lab, and estimate the annual cost.

Other Cost-Incurring Q 3.2.7 Identify impacts and relevant costs or labor effort. Determine if due Impacts to accum or release.

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Al Aluminum As Arsenic AC Asbestos Cement AWWA American Water Works Association

BMP Best Management Practice

CIP Capital Improvement Plan

DIC Dissolved Inorganic Carbon DOC Dissolved Organic Carbon DS Distribution System

EPA Environmental Protection Agency (United States) ERU Equivalent Residential Unit

Fe Iron FPS Feet per Second

GWUDI Groundwater Under the Direct Influence (of surface water)

HAV Health Advisory Value Hg Mercury HPC Heterotrophic Plate Count

ICP Inductively Coupled Plasma IRIS Integrated Risk Information System IQ Intelligence Quotient

HDPE High Density Polyethylene

LSL Lead Service Lines

MCL Maximum Contaminant Level MG Million Gallons MGD Million Gallons per Day Mn Manganese MS1 Mine shaft #1 MS2 Mine shaft #2

NIRS National Inorganics and Radionuclide Survey NTU Nephelometric Turbidity Unit

O&M Operations and Maintenance

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Pb Lead PF Peak Factor pH Negative logarithm of the activity of the hydronium ion PIG Pipeline Inspection Gauge PCMC Park City Municipal Corporation POE Point of Entry POU Point of Use PVC Polyvinyl Chloride PWD Philadelphia Water Department PWS Public Water Systems

RfD Reference Dose for Chronic Oral Exposure

SCADA Supervisory Control and Data Acquisition SM Standard Methods SMCL Secondary Maximum Contaminant Level

TCLP Toxic Characteristic Leaching Procedure TCR Total Coliform Rule Tl Thallium

UDF Unidirectional Flushing

WHO World Health Organization WRF Water Research Foundation WTP Water Treatment Plant

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