United States
Environmental Protection
Agency
Elevated Lead in D.C. Drinking Water - A
Study of Potential Causative Events, Final
Summary Report
Office of Water (4607M) EPA 815-R-07-021 www.epa. gov/safewater August 2007
Printed on Recycled Paper
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Authorship:
This report was developed under the direction of EPA's Office of Ground Water and
Drinking Water and was prepared by HDR/EES through EPA's contract with
Environomics, Inc. Questions concerning this document should be addressed to:
Kira Smith
Office of Ground Water & Drinking Water
U.S. Environmental Protection Agency
Mail Code 4607M
1200 Pennsylvania Avenue NW
Washington, DC 20460-0001
Email: Smith.Kira@epamail.epa.gov
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Elevated Lead in D.C. Drinking Water-A Study of Potential Causative Events
Final Summary Report
Table of Contents
EXECUTIVE SUM MARY 1
1. INTRODUCTION AND SUMMARY 2
1.1 Background 2
1.2 Purpose of Study 3
1.3 Study Findings 3
1.3.1 Combination of Factors that Contributed to Lead Release 3
1.3.2 Causative Events 6
1.3.3 Potential Sources of Lead Release 8
1.4 Organization of Report 11
2. HISTORY AND EVALUATION OF LEAD MONITORING PROGRAM 12
2.1 Sampling Protocols 12
2.2 First-Draw Lead Results 13
2.2.1 Historical Data 13
2.2.2 LCR 90th Percentile Reassessment 16
2.3 Second-Draw Lead Results 16
2.4 Designation of Optimal Corrosion Control Treatment 17
2.5 Lead Service Line Replacement Program 20
3. WATER TREATMENT FACILITIES 22
3.1 Water Quality at Distribution System Entry Points 22
3.2 Findings from Sanitary Surveys of Water Treatment Facilities 24
4. DISCUSSION OF DISTRIBUTION SYSTEM CONDITIONS 26
4.1 Water Quality Trends 26
4.1.1 pH 26
4.1.2 Alkalinity 27
4.1.3 Temperature 28
4.1.4 Total Chlorine 30
4.1.5 Conductivity 30
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4.2 Lead Sources 31
4.2.1 Lead Source Evaluation Using Lead Profiling 32
4.2.2 Source Water Lead Levels 36
4.2.3 Distribution Mains 36
4.3 Findings from Sanitary Surveys in the Distribution System 37
5. CAUSATIVE FACTORS OF ELEVATED LEAD LEVELS 38
5.1 Combination of Factors Contributed to Lead Release 39
5.1.1 Sources of Lead 41
5.1.2 Historical Use of Elevated Free Chlorine 41
5.1.3 Low pH Operating Levels and pH Variations 41
5.1.4 Conversion from Elevated Free Chlorine to Chloramines 41
5.2 Lead Scales and Solubility 41
5.2.1 Oxidation Reduction Potential (ORP) 42
5.2.2 Lead Scales 44
5.2.3 Theory and Ongoing Research Pertaining to Pb (IV) 46
5.3 Lead Release from Piping Systems and Other Lead-Bearing Materials 47
5.3.1 Soluble Lead from Piping 47
5.3.2 Particulate Lead from Piping 48
5.3.3 Faucets, Solder, and Other Home Plumbing 51
5.3.4 Distribution Mains 52
5.4 Impacts of Historical Use of Elevated Free Chlorine Concentrations 53
5.5 Distribution System pH Levels and pH Variations 55
5.5.1 pH Variations 56
5.5.2 Spatial pH Variations 58
5.5.3 Seasonal pH Variations 58
5.5.4 Lower pH and Modified OCCT 59
5.5.5 Optimal Corrosion Control Treatment (OCCT) 59
5.6 Conversion from Elevated Free Chlorine to Chloramines for Final Disinfection 61
5.6.1 LCR Monitoring Results 61
5.6.2 Historical Data on Wastewater Metals 64
5.6.3 Lead Levels during Temporary Disinfectant Change 64
5.6.4 Lead Profiling during Temporary Disinfectant Change 66
5.7 Distribution System Water Quality Characteristics 74
5.7.1 Alkalinity 74
5.7.2 Temperature and Specific Conductance 74
5.7.3 Natural Organic Matter 75
5.7.4 Nitrification 76
5.8 Galvanic Corrosion of Lead Service Lines 76
5.9 Effect of Grounding Currents on Lead-Bearing Components 78
5.10 City-Wide Meter Replacement Program 80
5.11 Drought Conditions and Effects on Corrosivity of DCWASA Water 81
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6. CURRENT STATUS OF DCWASA SYSTEM AND POSSIBLE FOLLOW-ON WORK 85
6.1 Current LCR Compliance Status of DCWASA System 85
6.2 Possible Follow-on Evaluation 85
6.2.1 DCWASA-Related Follow-on Evaluations 85
6.2.2 Research to Enhance Understanding of Lead Release 86
7. ABBREVIATIONS 89
8. REFERENCES 90
List of Tables
Table 1. Summary of possible causative events affecting lead release 6
Table 2. Summary of possible sources of lead release 9
Table 3. Monitoring program for first-draw lead samples - comparisons of DCWASA and
HDR/EES calculations 15
Table 4. Monitoring program for second-draw lead samples - comparisons of DCWASA and
HDR/EES calculations 17
Table 5. Minimum required pH for distribution system entry points 18
Table 6. Sources of data and information for water quality parameters 26
Table 7. Disinfection regime corresponding to when profile data was collected at sites
within the DCWASA system 33
Table 8. Average lead concentration and mass for profiles during the temporary disinfectant
change (12 profiles) and chloramination (15 profiles) 35
Table 9. Summary of Optimal Corrosion Control Treatment (OCCT) Decisions and Actions 40
Table 10. Summary evaluation of data and information - lead release from piping systems 51
Table 11. Summary evaluation of data and information - faucets, solder, and other home
plumbing 52
Table 12. Summary evaluation of data and information - water in distribution mains 52
Table 13. Summary evaluation of data and information - distribution system pH variations 61
Table 14. LCR lead results for January through June 2003 65
Table 15. LCR lead results for March through June 2004 66
Table 16. Maximum lead levels measured from profiles during chloramination and periods of
temporary disinfectant change to free chlorine 73
Table 17. Summary evaluation of data and information - conversion from free chlorine to
chloramines for final disinfection 73
Table 18. Summary evaluation of data and information - galvanic corrosion of lead service
lines 78
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Table 19. Summary evaluation of data and information - grounding currents that affect
corrosion of lead-bearing components 79
Table 20. Lead release from bronze water meters in laboratory study 80
Table 21. Summary evaluation of data and information - city-wide meter replacement
program 80
Table 22. Source water quality data (1998 through 2000) 81
Table 23. Summary evaluation of data and information - drought conditions and their
effect on corrosivity of DCWASA water 84
List of Figures
Figure 1. Timeline of operational events and key regulatory determinations for the DCWASA
system 5
Figure 2. Finished water pH compared to minimum required pH at distribution system entry
points (July 1, 2000-June 30, 2004) 19
Figure 3. Average distribution system pH measured at different OWQP monitoring sites over
different time periods. The 3-month running average pH value is shown for comparison
(July 1,2000-October26, 2004) 20
Figure 4. Finished water pH measured at the distribution system entry points (1998 - 2004).
Drought periods are designated using solid and dashed lines 22
Figure 5. Finished water alkalinity measured at the distribution system entry points (1998 -
2004; no alkalinity data was available for 2000-2001) 23
Figure 6. Finished water temperature at distribution system entry points (1998-2004) 23
Figure 7. Finished water chlorine residual concentration at distribution system entry points
(1998-2004) 25
Figure 8. Specific conductance of untreated water (1999-2002) 25
Figure 9. Average daily pH of water samples collected at various sampling sites within the
distribution system (1998 - 2004). The 3-month running average pH in the distribution
system is shown for comparison 27
Figure 10. Average daily alkalinity of water samples collected from various sampling sites
within the distribution system (1998 - 2004). The 3-month running average alkalinity
value in the distribution system is shown for comparison 28
Figure 11. Average daily pH and alkalinity of water samples collected at various sampling
sites within the distribution system (1996-2004) 29
Figure 12. Average daily temperature of water collected from sampling sites within the
distribution system (2001 -2004) 29
Figure 13. Average daily total chlorine concentration for water samples collected from various
sampling sites throughout the distribution system (2001 -2004) 30
IV
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Figure 14. Average daily specific conductance for water samples collected from various
sampling sites throughout the distribution system (1998 - 2004). The 3-month running
average specific conductance for water in the distribution system is
shown for comparison 31
Figure 15. Lead profile for tap water samples from House #8
(sample collected March 9, 2004) 33
Figure 16. Average mass of lead contributed from various sources for profiles experiencing a
temporary switch to free chlorine and those exposed to chloramination disinfection
(unadjusted for actual volume of exposure) 35
Figure 17. ORP (mV) vs. date for the 4th High Pressure Zone during the temporary
disinfectant change (April 2, 2004 through May 7, 2004) and after the temporary
disinfectant change 43
Figure 18. Potential-pH diagram for the lead system corresponding to DC WASA water
(Schock and Giani, 2004) 45
Figure 19. Average contribution of dissolved and particulate lead as a percentage of the total
lead concentration in distribution system water samples (December 2003 through March
2004) 48
Figure 20. Lead profile data for House #22 (sample collected April 30, 2004) under conditions
of water hammer that cause high levels of particulate lead release (Particulate Lead = Total
Lead-Soluble Lead) 49
Figure 21. Free and total chlorine residual as a function of time illustrating periods of lower
chlorine residuals at the distribution system entry points in the early 1990s (January 1992
through December 2004) 54
Figure 22. Average free and total chlorine concentrations for water samples collected from
different sampling sites within the distribution system (1998-2004) 54
Figure 23. Average Free Chlorine Concentration (over the LCR compliance period) and 90th
Percentile Lead vs. Time 55
Figure 24. Average daily pH at the distribution system entry points (Dalecarlia and McMillan)
and in the distribution system (1998 through 2004) 57
Figure 25. Difference between the average water pH at the distribution system entry points and
the average pH of water collected at different sampling sites throughout the distribution
system (1998 through 2004) 58
Figure 26. Average daily pH and lead concentrations in first draw water samples before and
after the conversion from free chlorine to chloramines as the residual disinfectant 60
Figure 27. Lead concentrations in first draw water samples collected during different time
intervals (July 1997 through December 2004) 63
Figure 28. Average and 90th percentile lead concentrations in first draw water samples during
different compliance periods (January 1992 through December 2004) 63
Figure 29. Average lead concentrations in first draw water samples collected during different
months (July 1997 through October 2004) 64
Figure 30. Lead profiles for House #1 when a) chloramines were being used as the disinfectant
(sample collected January 13, 2004) and b) during a temporary switch to free chlorine as the
disinfectant (sample collected April 29, 2004) 68
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Figure 31. Lead profiles for House #2 when a) chloramines were being used as the disinfectant
(sample collected February 24, 2004) and b) during a temporary switch to free chlorine as
the disinfectant (sample collected April 26, 2004) 69
Figure 32. Lead profiles for House #3 when a) chloramines were being used as the disinfectant
(sample collected March 30, 2004) and b) during a temporary switch to free chlorine as the
disinfectant (sample collected April 30, 2004) 70
Figure 33. Lead profiles for House #4 when a) chloramines were being used as the disinfectant
(sample collected March 31, 2004) and b) during a temporary switch to free chlorine as the
disinfectant (sample collected May 7, 2004) 71
Figure 34. Lead profiles for House #5 when a) chloramines were being used as the disinfectant
(sample collected February 9, 2004) and b) during a temporary switch to free chlorine as the
disinfectant (sample collected May 18, 2004) 72
Figure 35. Average daily alkalinity and lead concentration in first draw water samples before
and after the conversion from free chlorine to chloramines as the residual disinfectant 75
Figure 36. Surface potential along the length of directly coupled lead and copper
service lines 77
Figure 37. Impressed current impacts for separate DC (upper) and AC (lower) tests on surface
potential of a lead service line coupled to copper tubing 79
Figure 38. Average daily specific conductance of water at the distribution system entry points
during drought periods 82
Figure 39. Average daily alkalinity of water at the distribution system entry points during
drought periods 83
Figure 40. Average daily temperature of water at the distribution system entry points during
drought periods 83
VI
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Appendix A
Timeline
Summary of Administrative Orders
Summary of Sanitary Surveys
Supplement to History and Evaluation of Lead Monitoring Program
Summary of Corrosion Control Studies
Summary of Lead Service Line Replacement Program
Summary of Correspondence on Designation of Optimal Corrosion Control Treatment
Lead Profiles
Appendix B
Study Approach
Appendix C
Peer Review Information
VII
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EXECUTIVE SUMMARY
The District of Columbia Water and Sewer Authority (DCWASA) owns and operates a
system that delivers water produced by the U.S. Army Corps of Engineers Washington
Aqueduct (WA) to customers in Washington, D.C. During compliance monitoring for the
Lead and Copper Rule (LCR) in July 2000 through June 2001, DCWASA exceeded the
15-|o,g/L action level (AL) for lead at the 90th percentile in home tap sampling. DCWASA
repeatedly exceeded the AL during subsequent monitoring through the period ending in
December 2004.
A combination of factors - not a single source or a single causative event - contributed
to the problematic release of lead in water at consumers' taps in the DCWASA system.
The primary source of lead release was attributed to the presence of lead service lines
(LSLs) in the DCWASA service area. Since the mid-1990s, three notable occurrences in
the DCWASA system likely contributed to elevated lead releases during 2000 through
2004. These are highlighted below.
During the mid-1990s, the concentration of residual free chlorine was increased to the
range of 2.2 to 3.2 mg/L for the purpose of controlling coliform occurrence in the water
distribution system. These relatively high free chlorine concentrations likely facilitated
the formation of Pb (IV) scales in the form of lead dioxide (PbO2) in lead service pipes.
These Pb (IV) scales exhibit relatively low lead solubility under normal ranges of pH
and alkalinity in public water systems when compared to Pb (II) compounds. Lead
scales on the interior of lead service lines are likely comprised of various forms of
lead, including both Pb (II) and Pb (IV), and the chemical composition of the scales
likely changes with varying water quality conditions.
The pH of the distributed water in Washington, D.C. exhibited seasonal variations that
fluctuated from approximately 7.0 to 8.9 during the period from 1992 to 2004. pH
levels at the lower end of this range would not be considered optimal for lead
corrosion control according to the conventional understanding that forms the basis for
the LCR and assumes the presence of Pb (II) as the dominant scale. In D.C.,
however, and as stated above, relatively high free chlorine concentrations likely
facilitated the formation of Pb (IV) as the dominant scale, which exhibits relatively low
lead solubility at the lower pH levels experienced in the DCWASA system.
On November 1, 2000, WA converted the residual disinfectant from free chlorine to
chloramines for the purpose of lowering disinfection byproducts to meet new
regulatory requirements. This conversion facilitated a reduction in oxidation reduction
potential (ORP) to a range that favors the predominance of Pb (II) scales, which are
highly influenced by low and fluctuating pH levels. This conversion from free chlorine
to chloramines likely changed the nature of the predominant scale from Pb (IV) to
Pb (II) and thus facilitated an increase in the release of lead from the lead service lines
into the water at consumers' taps.
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1. INTRODUCTION AND SUMMARY
This section provides the following:
Background information regarding operating conditions and events prior to and during
the monitoring periods when the District of Columbia Water and Sewer Authority
(DCWASA) exceeded the lead action level (AL) of the Lead and Copper Rule (LCR)
during compliance monitoring in 2000 through 2004.
A description of the study's purpose and an in-depth analysis of potential causative
events.
A summary of the findings of the study. Possible causes of high lead levels in
DCWASA tap samples are identified and discussed.
An overview and road map for the reader regarding the contents of subsequent
sections in this report.
1.1 Background
DCWASA owns and operates a system that delivers water to Washington, D.C. Water is
diverted from the Potomac River and treated at two water treatment plants, Dalecarlia
and McMillan, operated by the U.S. Army Corps of Engineers' Washington Aqueduct
(WA). Both water treatment plants provide finished drinking water to the DCWASA
service area.
Historically, full conventional treatment has been provided using aluminum sulfate (alum)
for coagulation, gravity filtration, free chlorine for disinfection, fluoride addition for dental
health, and lime addition for reducing corrosion (USAGE, 2006). The pH of the
distributed water exhibited seasonal variations that fluctuated from approximately 7.0 to
8.9 from 1992 to 2004. During the mid-1990s, WA increased the concentration of free
chlorine to the range of 2.2 to 3.2 milligrams per liter (mg/L) for the purpose of controlling
coliform occurrence in the DCWASA distribution system. On November 1, 2000, WA
converted from using free chlorine to chloramines at both plants to provide a residual
disinfectant in the distribution system less likely to form regulated disinfection
byproducts. In August 2004, orthophosphate was added at both plants for corrosion
control and pH levels were adjusted to accommodate this new chemical treatment.
DCWASA met the lead AL of 15 micrograms per liter (|o,g/L) per the LCR during
compliance monitoring from July 1994 through September 1999. In February 2000,
USEPA Region 3 reduced the requirement for LCR tap monitoring to once per year at
50 sites as allowed by the LCR. At the request of WA and DCWASA, the minimum pH
requirement at entry points and distribution system sites was lowered and the letter of
OCCT designation was implemented with the approval of United States Environmental
Protection Agency (USEPA) effective July 1, 2000.
Subsequently, average pH levels were observed to be as low as approximately 7.0 in
the distribution system during 2001 and 2002. Reduced monitoring continued through
the LCR compliance monitoring period of July 2001 - June 2002 because DCWASA had
reported LCR 90th percentile monitoring results below the regulatory AL during July
2000 - June 2001. In 2004, USEPA Region 3 reassessed 90th percentile results for the
LCR monitoring period of July 2000 - June 2001. USEPA determined that the originally
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reported LCR 90th percentile values had not included all samples, and that the AL had
been exceeded during the July 2000 - June 2001 LCR compliance monitoring period
(Rizzo, 2005b). DCWASA also exceeded the AL in five LCR monitoring periods
subsequent to the July 2000 - June 2001 monitoring period. DCWASA was required by
USEPA to implement, among other LCR requirements that follow exceedance of the AL,
a lead service line replacement program per the LCR. A lead service line replacement
program was commenced in June 2003.
1.2 Purpose of Study
The presence of lead is pervasive in piping systems and plumbing components including
lead service lines (LSLs), brass faucets, lead-tin solder, meters, valves, and other
components. Lead can enter the water supply from lead-bearing materials in either the
soluble or particulate form.
USEPA decided to perform an in-depth analysis that would document and determine, to
the extent possible, the source(s) and cause(s) of elevated lead levels at DCWASA
consumers' taps. USEPA anticipates that this evaluation, which is summarized in this
document, can be used by USEPA, states, and public water systems to assist in their
efforts to reduce lead in drinking water and avoid the conditions that resulted in elevated
lead levels in Washington, D.C. in 2000 - 2004.
1.3 Study Findings
This section provides the following:
A summary of findings, including an evaluation of the combination of factors that
contributed to lead release at consumers' taps.
A description of the causative events and possible sources of lead that contributed to
lead releases in the DCWASA service area.
1.3.1 Combination of Factors that Contributed to Lead Release
Figure 1 illustrates the timeline of events from 1992 to 2004 highlighting operations and
regulatory compliance decisions, 90th percentile lead levels, shifts in disinfectants and
pH, coliform events, and other key dates and related activities associated with lead
released at consumers' taps in the DCWASA service area.
Based on a review of existing conditions and service line profiling, the primary source of
lead release was attributed to the presence of lead service lines in the DCWASA service
area. Since the mid-1990s, three notable occurrences in the DCWASA system likely
contributed to elevated lead releases during 2000 through 2004. These notable
occurrences pertained to water quality changes and conditions as described below.
The first notable water quality change occurred in the mid-1990s when the
concentration of residual free chlorine was increased to 4.0 mg/L and subsequently
maintained in the range of 2.2 to 3.2 mg/L; this change was implemented for the
purpose of controlling coliform occurrence in the water distribution system.
These relatively high free chlorine concentrations likely facilitated the formation of
Pb (IV) scales in the form of lead dioxide (PbO2) in lead service lines. The
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conventional understanding that forms the basis for the LCR assumes the presence
of Pb (II) as the dominant scales. Lead scales on the interior of lead service lines are
likely comprised of various forms of lead, including both Pb (II) and Pb (IV), and the
chemical composition of the scales likely changes with varying water quality
conditions. Lead dioxide scales generally exhibit relatively low lead solubility under
normal ranges of pH and alkalinity in public water systems when compared with
Pb (II) compounds.
The second notable water quality condition pertains to the fluctuating and low pH of
the water in the DCWASA system. pH of the water is an important factor in the
control of lead solubility. The pH of the distributed water in Washington, D.C.
exhibited seasonal variations that fluctuated from approximately 7.0 to 8.9 during
1992 to 2004. pH levels at the lower end of this range are not considered optimal for
lead corrosion control based on the conventional understanding of lead solubility per
the LCR, assuming that Pb (II) is the dominant form of scales.
In Washington D.C., as stated above, relatively high free chlorine concentrations
applied to the service area during the mid-1990s likely facilitated the formation of
Pb (IV) as the dominant scale. Pb (IV) exhibits relatively low lead solubility at the
lower pH levels experienced in the DCWASA system. Consequently, lead levels
were low during LCR compliance monitoring during the mid-1990s.
The third notable water quality change occurred when WA converted the residual
disinfectant from free chlorine to chloramines beginning November 1, 2000. The
residual disinfectant conversion was implemented for the purpose of lowering
disinfection byproducts to meet new regulatory requirements. This conversion
facilitated a reduction in oxidation reduction potential (ORP) to a range that favors
the predominance of Pb (II) scales. Pb (II) species generally are highly influenced by
low and fluctuating pH levels. This conversion from free chlorine to chloramines
likely facilitated the release of lead in water while operating at low, fluctuating pH
conditions. Lead release likely increased after pH was allowed to drop further when
the minimum pH requirements at entry points and distribution sites were lowered at
the request of WA and DCWASA and implemented with the approval of USEPA
effective July 1, 2000.
In summary, the combination of the three water quality conditions described above -
historical use of elevated free chlorine concentrations, low pH operating levels and pH
variations, and conversion from free chlorine to chloramines - in addition to the
presence of lead service lines in the DCWASA service area, likely caused and
contributed to elevated lead levels during LCR compliance monitoring periods from July
2000 through December 2004.*
It should be noted that not all systems containing lead-bearing materials are expected to exceed
the LCR 90th percentile for lead when implementing a switch from free chlorine to chloramines.
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Figure 1. Timeline of operational events and key regulatory determinations for the DCWASA system
[Note: DCWASA either met the Action Level or was not required to perform monitoring from 1994 to 2000. Available LCR compliance data for DCWASA are summarized
and discussed in Section 2 of this report.]
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1.3.2 Causative Events
This section identifies possible causative events and provides an evaluation of the
relative contribution of each event to elevated lead levels in DCWASA consumers' taps.
For the purpose of this report, a causative event is defined as a notable occurrence,
such as change in treatment or operations, or an external event or condition that
potentially affected water quality and lead release in the DCWASA system.
The primary source of lead release was attributed to the presence of lead service lines in
the DCWASA service area (see Section 1.3.3). Findings pertaining to causative events
are summarized in Table 1 and discussed below.
Table 1. Summary of possible causative events affecting lead release
Causative Event
Evidence and Likelihood of Causative Event Affecting
Lead Release in Water at Consumers' Taps
Historical use of
elevated free chlorine
concentrations
The increase in free chlorine concentration in the mid-1990s
likely modified ORP conditions in the DCWASA service area
that would facilitate a change in predominant lead scales
from Pb (II) to Pb (IV) species. Theoretical considerations
support the likelihood that lead solubility would be lower for
Pb (IV) species in DCWASA water. Although the system was
operated at low and varying pH levels, DCWASA met the AL
during LCR compliance monitoring from 1994 to 2000.
Distribution system pH
levels and pH variations
pH levels and pH variations appear to be important
contributing factors to high lead release from scales. Low and
varying pH levels in the system were not optimum for lead
control, especially Pb (II) control.
Conversion from
elevated free chlorine to
chloramines for final
disinfection
The change in disinfectant from elevated free chlorine levels
to chloramines likely modified redox conditions that would
facilitate a change in predominant lead scale from Pb (IV) to
Pb (II) species. Based on available evidence, it is highly likely
that the different oxidation-reduction potential of the water
and responses of scales were involved in significant lead
release, especially at low pH levels.
Drought conditions
Statistical analyses of specific conductance, alkalinity, and
temperature were performed during drought conditions. Data
yield no definitive trends.
1.3.2.1 Historical Use of Elevated Free Chlorine Concentrations
Lead scales on the interior of lead service lines are likely comprised of various forms of
lead, and the chemical composition likely changes with changing operating conditions
including changes in water quality. As mentioned previously, the concentration of
residual free chlorine was increased during the mid-1990s to the range of 2.2 to 3.2
mg/L for the purpose of controlling coliform occurrence in the water distribution system.
6
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These relatively high free chlorine concentrations likely facilitated the formation of Pb (IV)
scales in the form of PbO2 in lead service lines.
Analysis of lead service line specimens by Schock and Giani (2004) confirmed that
tetravalent lead (Pb (IV)) scale was present on interior lead pipe surfaces in the
DCWASA system. The Pb (IV) solid, PbO2, is thought to be much less soluble over the
normal range of pH and alkalinity in public water systems than common Pb (II) solids
including cerussite, PbCO3, and hydrocerussite, Pb3(OH)2(CO3)3, as described by
Schock et al. (2001). Accordingly, the relatively high redox potential of the DCWASA
water due to the high free chlorine concentration likely reduced the amount of lead
release from lead pipe, and therefore, DCWASA met the AL during LCR compliance
monitoring from 1994 to 2000.
1.3.2.2 Distribution System pH Levels and pH Variations
Conventional understanding of lead control in drinking water per the LCR is based on
the presumption that Pb (II) solids control lead solubility and that manipulation of basic
water chemistry (pH, alkalinity) can produce stable mineral forms, including cerussite
and hydrocerussite, that passivate a corroding lead surface. Typically, lower pH levels
contribute to higher lead solubility, and higher pH levels are associated with lower lead
solubility.
The Potomac River source water quality fluctuates seasonally and some of these
fluctuations are observed in the finished water. To avoid significant calcium carbonate
(CaCO3) precipitation, minimum pH levels in the finished water were varied seasonally
as established by the USEPA on May 17, 2002 (retroactive to the monitoring period
beginning July 1, 2000) as Optimal Corrosion Control Treatment (OCCT). As such, the
pH of water entering the distribution system was purposefully varied by WA. The pH
varied even more within the distribution system due to other factors such as seasonal
fluctuations and site-specific conditions in the distribution system.
Historical water quality data collected at the Dalecarlia and McMillan water treatment
plants indicate seasonal pH fluctuations that varied from approximately 7.5 to 8.8 during
1992 to 2004. Distributed water pH was allowed to drop further below pH 7.5 when the
pH requirements at entry points and distribution sites were lowered at the request of WA
and DCWASA and implemented with the approval of USEPA effective July 1, 2000. The
lowering of average pH values during monitoring periods from July 2000 to December
2004 is an important factor that potentially contributed to lead release in DCWASA tap
water, especially when chloramination conditions favored the formation and dominance
of Pb(ll) scales.
Elevated lead levels were reported during the July 2000 - June 2001 LCR monitoring
period. pH fluctuations occurred before, during, and after the July 2000 - June 2001
LCR monitoring period. Thus, pH fluctuations alone were not likely the cause of
elevated lead levels. Before the disinfectant conversion to chloramines, DCWASA met
the requirements of the LCR while using elevated free chlorine concentrations.
DCWASA exceeded the AL for lead during the monitoring period that coincided with the
change in disinfectant and the lowering of the operating pH level. The change in pH
operating levels, and pH variations in the distribution system, were therefore likely
contributing factors to elevated lead levels at consumers' taps.
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1.3.2.3 Conversion from Elevated Free Chlorine to Chloramines for Final
Disinfection
On November 1, 2000, DCWASA converted from free chlorine to chloramines as the
residual disinfectant to reduce the potential formation of regulated disinfection
byproducts. As stated earlier, the relatively high concentration of free chlorine that was
used for residual disinfection prior to the conversion to chloramines likely facilitated the
formation and predominance of Pb (IV) species in lead service lines and other lead-
bearing components. The different oxidation potentials of elevated free chlorine and
chloramines, and the responses of lead scales (found on lead service lines, and possibly
other lead-bearing components) to this change in disinfectant were likely significant
factors in the release of lead into tap water.
Theoretical and empirical evidence documenting this potential cause of lead release
includes the following: lead scale analysis, scale formation and solubility analysis, and
tap sampling from lead service lines. Common Pb (IV) solids in an elevated redox
condition, such as in the presence of elevated free chlorine, include PbO2. In
comparison, common Pb (II) solids at lower redox conditions are generally considered to
be predominated by lead species such as cerussite and hydrocerussite (Schock et al.,
2001). Hence, changing the oxidation-reduction state of the water through a disinfectant
change likely increased the amount of lead release from lead pipe. The change from
elevated levels of free chlorine to chloramines lowered the ORP of the distributed water,
likely causing a shift in predominance from Pb (IV) to Pb (II) species, and thus facilitating
the release of lead at consumers' taps.
Further, tap sampling in the form of lead profiling conducted at specific home locations
before and after the temporary disinfectant change in 2004 provides additional
information regarding the likelihood that this conversion was a factor in lead release by
the service line and uptake by water passing through the pipe.
1.3.2.4 Drought Conditions and Effects on Corrosivity of DCWASA Water
Drought conditions may have resulted in different water quality conditions in the source
waters that could have influenced finished water quality and corrosion potential. There
is a substantial amount of information and data on the source water quality during these
time periods, but it is difficult to relate it to the corrosion potential of the distributed water.
The statistical analysis of specific conductance, alkalinity, and temperature during
drought conditions, which was conducted as part of this investigation, does not implicate
drought as a major factor in lead release. Drought conditions may have played a
contributing role in increased lead corrosion; however, the impact of drought conditions
on water quality parameters that affect corrosion was not investigated further.
1.3.3 Potential Sources of Lead Release
This section identifies possible sources of lead in the DCWASA system. For the
purpose of this report, a source of lead release is defined as a piping material or
plumbing component that contains lead, including brass faucets, lead service lines,
solder, meters, etc. Galvanic corrosion and electrical grounding are also included in this
discussion because these conditions can induce the release of lead from a piping
material or plumbing component. This section also provides an evaluation of the relative
likelihood of lead release from each of the possible sources. Findings are summarized
in Table 2 and discussed below.
8
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Table 2. Summary of possible sources of lead release
Source of Lead
Lead service lines
Faucets, solder, and
other home
plumbing
Galvanic corrosion
of lead service lines
Grounding currents
City-wide meter
replacement
Distribution mains
Evidence and Likelihood of Source Affecting Lead Release
in Water at Consumers' Taps
Lead profiling indicates that the majority of lead released is from
lead service lines and is predominantly in the soluble form.
Intermittent spikes of particulate lead were noted.
Lead profiling indicates some contribution, but these sources are
likely not the major contributor. Findings related to this causative
factor are also based on reported lead release from premise
piping components in similar plumbing systems.
Data are limited but indicate low likelihood of contribution to lead
release.
Data are limited but indicate low likelihood of contribution to lead
release.
Data are limited and indicate some soluble lead release. Major
impact on lead levels at consumers' taps is unlikely.
Published reports indicate that this source is not a meaningful
source of lead. Some flushed samples are very low in lead levels
and others are elevated, which is likely due to release of lead
from service lines and premise piping rather than from
distribution mains.
1.3.3.1 Lead Service Lines
Given that many service lines connected to the DCWASA distribution system are made
of lead, and profiling indicates that the majority of lead release was from lead service
lines, lead service lines are therefore considered the major source of lead release in the
DCWASA system. Further, lead scales on the interior of lead service lines likely are
comprised of a variety of compounds that co-exist in the lead scales. The conversion to
chloramines, along with varying pH levels, likely affected the stability of scales and thus
resulted in release of lead from the lead service lines and uptake by water at consumers'
taps in the DCWASA system.
The potential exists for lead-bearing scales to be detached from the service line or home
plumbing during plumbing disturbances and to enter the water column as particles. One
example of this scenario is the disturbance associated with partial replacement of lead
service lines, which results in release of lead scales from the portion of the line
remaining in service. Particulate lead spikes do occur in tap samples, but they are
relatively infrequent, of short duration, and thus are not likely the major factor in causing
the sustained high lead levels at the consumers' taps.
1.3.3.2 Faucets, Solder, and Other Home Plumbing
Faucets, solder, and other home plumbing can potentially contribute to total lead
measured in water collected at the tap. Brass faucets and 50 : 50 tin : lead solder,
-------
historically used to join copper piping in home plumbing systems, contain lead. Lead
profiling indicates that home plumbing components are a likely contributing source, but
not the major source of lead in tap samples. Analogous lead profiling data also indicate
that common end-use plumbing components contribute lead to standing water. In
addition to site-specific lead profiling, industry data demonstrate that home plumbing
potentially contributes to total lead. However, available data do not provide compelling
evidence that faucets, solder, and other home plumbing were predominant lead
contributors in the DCWASA service area.
1.3.3.3 Galvanic Corrosion of Lead Service Lines
In the service lines and premise piping systems, there are sites where lead and other
metals are directly connected, resulting in galvanic couplings. The coupling of these
dissimilar metals could result in the release of lead to the water. There is very little
information on this potential cause and no site-specific data are available for review. A
laboratory investigation of this issue conducted by Reiber and Dufresne (2005) regarding
DCWASA conditions indicates that galvanic couplings likely contribute very little to lead
release.
1.3.3.4 Grounding Currents that Affect Corrosion of Lead-Bearing Components
It is possible that lead may be released to the water column at sites where the electrical
systems have been grounded to water piping systems. There is very little information on
the potential effect of grounding currents on corrosion of lead-bearing materials, and no
site-specific data are available. An investigation of this cause conducted by Reiber and
Dufresne (2005) regarding DCWASA conditions indicates that grounding likely
contributes very little to lead release.
1.3.3.5 City-Wide Meter Replacement Program
There are two potential sources of lead release and uptake by the water associated with
meter replacement: (1) disturbance of adjacent piping, causing release of scales
containing lead (particles); and (2) release of soluble lead directly from the meter itself
due to water chemistry. There are data available on water quality conditions and the
effect on lead release from meters in a site-specific study (Keefer and Giani, 2005).
However, little or no data are available on the potential release of particulate lead
associated with meter replacement. Testing of meters for lead release indicated that
some release occurred, but the contribution is small and likely not a major contributor to
elevated lead at the tap.
1.3.3.6 Distribution Mains
Water in the utility's distribution mains was assessed during this study by reviewing
pertinent reports and by evaluating lead profiling data collected after a thorough flushing
of the tap for a period considered sufficient to bring fresh water in from the main. The
reports (Keefer and Giani, 2005; Giani et al., 2005a) indicate that lead from the
distribution system is very low. However, lead profiling yielded conflicting data regarding
the presence and contribution of lead in the distribution mains. Many flushed samples
were reported at detection limits for lead, but others were reported at elevated lead
levels. The higher than expected lead levels could have been caused by either release
of lead from components in the utility system, or by release of lead from the lead service
10
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lines or premise piping and plumbing. Based on available data and information, it is the
study team's best professional judgment that the distribution system components were
not a major contributing factor in lead levels at consumers' taps.
1.4 Organization of Report
This section (Section 1) summarizes the findings of a study conducted by HDR/EES to
document and evaluate the potential causative events and parameters contributing to
the elevated lead levels in the Washington, D.C. drinking water system. The remaining
sections of this report provide supporting data, information, and discussion. The
contents of the remaining sections of this report are highlighted below.
Section 2 describes the history of DCWASA's lead monitoring program and
HDR/EES's independent evaluation of reported compliance data.
Section 3 provides documentation of reported water quality data at distribution
system entry points (i.e., the Dalecarlia and McMillan Water Treatment Plants) and
findings from sanitary surveys of water treatment facilities.
Section 4 provides documentation of water quality data collected in the distribution
system, identification of the occurrence and evaluation of lead sources, and findings
from sanitary surveys in the distribution system.
Section 5 provides an evaluation of the combination of factors that contributed to the
problematic release of lead. This section also provides an in-depth discussion of
causative factors that potentially contributed to elevated lead levels including each of
the possible causative events (i.e., historical use of elevated free chlorine
concentrations; distribution system pH levels and pH variations; conversion from free
chlorine to chloramines for final disinfection; and drought conditions) and each of the
identified possible sources of lead release (i.e., lead service lines; faucets, solder,
and other home plumbing; galvanic corrosion of lead service lines; grounding
currents; city-wide meter replacement; and distribution mains).
Section 6 provides a brief summary of the current LCR compliance status of the
DCWASA system and it identifies possible follow-on work based on available
findings and conclusions drawn from this study.
Documents prepared as part of this evaluation include: (1) this Summary Report,
(2) supporting hard copy materials in three-ring binders, and (3) a data evaluation report
per the requirements of the Quality Assurance Project Plan (QAPP).
11
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2. HISTORY AND EVALUATION OF LEAD MONITORING
PROGRAM
This section includes the following:
The sampling protocols used for first- and second-draw sampling.
DCWASA's 90th percentile calculations for first- and second-draw lead results and
HDR/EES's reassessment of those results.
USEPA Region 3 designation of OCCT.
Description of DCWASA's lead service line replacement program.
USEPA Region 3 provided HDR/EES with laboratory sample reports; 90th percentile
calculations; and correspondence related to LCR monitoring, including first-draw and
second-draw samples. To facilitate data evaluation, hard copies of LCR compliance
data were entered into Excelฎ spreadsheets. In addition, HDR/EES received electronic
data files containing compliance monitoring data for the compliance periods of January
through June and July through December of 2004.
2.1 Sampling Protocols
First- and second-draw samples were analyzed for lead, copper, and iron using EPA
Method 200.8 at WA's certified laboratory. In addition, USEPA Region 3 provided
correspondence on designation of OCCT.
It appears that first-draw samples were collected by homeowners per LCR protocol.
Although not required by regulations, homeowners have routinely collected a second-
draw sample from their taps as well as requested by DCWASA. The protocol for
collecting this second-draw sample has changed through the years as described below.
DCWASA's 2004 sampling instructions directed homeowners to collect first-draw
samples after a 6- to 8-hour period of no water use. The second-draw sample was
collected at the same tap after allowing the water run at a slow pace until the water
turned cold. Prior to 2004, second-draw samples were collected immediately after the
first-draw sample without allowing the water to run until there was a temperature change
(Rizzo, 2005b). G. Rizzo of USEPA Region 3 estimated that DCWASA had been using
this sampling procedure for second-draw samples for several years prior to the LSL
replacement program, which commenced in 2003 (Rizzo, 2005b).
Prior to June 2002, information was not readily available regarding the recommended
protocol, nor were specific instructions on whether to remove the faucet aerator device
when collecting tap samples for LCR monitoring. In June 2002, which corresponds to
the last month of the July 1, 2001 through June 30, 2002 monitoring period, customers
were instructed to remove aerators. Following this, for the January 1 to June 30, 2003
full monitoring period, customers were again instructed to remove the devices before
sampling. This changed from the July 1 to December 31, 2003 monitoring period
onward, when customers were instructed to leave the aerators in place. Currently, these
instructions requiring customers to leave the aerators in place are still provided as the
appropriate sampling protocol (Smith, 2006). Similarly, instructions or a protocol for
12
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removal of point-of-use (POU) treatment devices during LCR sampling were not defined
until 2004 (Rizzo, 2004).
The relevance of both the aerator removal protocol and POU devices to lead levels and
LCR monitoring are discussed in Section 5 of this report.
2.2 First-Draw Lead Results
This section provides documentation of historical LCR first-draw lead sampling results as
reported by DCWASA and an evaluation of these data by HDR/EES. This section also
provides a summary of the 90th percentile reassessment by USEPA.
2.2.1 Historical Data
For LCR first-draw lead results, 90th percentile calculations prepared by DCWASA were
reviewed and re-calculated using either tabular data, laboratory data sheets, or Excel
spreadsheet data received from USEPA (tabular data and laboratory data sheets from
Data Binder 1 of 3 for Elevated Lead in D.C. Drinking Water- A Study of Potential
Causative Events, prepared by HDR/EES October 13, 2006; Excel spreadsheet data for
LCR compliance period of July - December 2004 received from USEPA). The results of
this analysis are summarized in Table 3, where values in bold indicate differences
between DCWASA results and results obtained by HDR/EES. These differences involve
total sample count, numerical ordering of sample results in the 90th percentile
calculations, and/or removal of duplicate compliance sites.
For comparison with the DCWASA results, HDR/EES calculated different values for 90th
percentile lead levels and/or the percentage of samples exceeding the AL for the
following monitoring periods:
July - December 1992
July - December 1993
January - June 1994
January - June 1999
July - December 2003
January-June 2004
July - December 2004
For the monitoring period from July to December 1992, DCWASA's 90th percentile lead
level does not exceed the AL, whereas the 90th percentile lead level calculated by
HDR/EES does exceed the AL. For the monitoring periods July - December 1993 and
January - June 1994, the 90th percentile lead levels calculated by HDR/EES are lower
than the 90th percentile lead level calculated by DCWASA. Both DCWASA and
HDR/EES calculations show that the 90th percentile lead level was greater than the 15-
ug/L AL during every monitoring period in years 2001 through 2004.
13
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A review of the July - December 1992 laboratory sampling information found that 30 of
the 125 samples exceeded the 15-ug/L action level for lead, but 15 of these 30 samples
were not listed in numerical order in DCWASA's 90th percentile calculations. When the
sample results were listed in numerical order, and duplicates were removed, the
resulting 90th percentile value calculated by HDR/EES was 39 ug/L compared with 15
ug/L reported by DCWASA.
For the January - June 1993 period, the total sample count appeared to be 115
compared with 114 in DCWASA's calculations; however, the 90th percentile result was
not affected. For the July - December 1993 period, four sites were originally listed as
duplicate samples; however, an additional six sites were found to also have been
sampled twice during this period, and one site was sampled three times. DCWASA
included all results from these sites in its calculations, and included all duplicate sites in
its sample count, for a total sample count of 131. HDR/EES's calculations used only one
value from these six additional duplicate addresses and one triplicate (the highest
value), for a total sample count of 119, and calculated a lower 90th percentile value than
DCWASA. By way of background, USEPA regulations, as clarified in a memorandum
dated November 23, 2004 (Grumbles, 2004), now require that all sample results from a
system's sampling pool be used in compliance calculations during the LCR monitoring
period. If confirmation samples are taken, both the original and confirmation must be
used in the 90th percentile calculation.
For the July - December 1997 and July - December 1998 compliance periods,
HDR/EES identified a different number of valid compliance samples; however, the
calculated 90th percentile result did not differ. For the January - June 1999 period,
laboratory sampling reports indicate that 17 first-draw samples had a lead concentration
of "<10 ppb"; however, DCWASA's 90th percentile calculations, which converted the
data to mg/L, show no samples with a lead concentration of <0.010 mg/L, which is
equivalent to <10 ppb. Two samples listed in DCWASA's 90th percentile calculations
(0.031 mg/L and 0.055 mg/L) could not be confirmed by the laboratory sample reports.
Also, DCWASA's 90th percentile calculations show a total of 106 first-draw samples, but
the laboratory summary report indicates only 81 first-draw-samples. Thus, HDR/EES's
calculation resulted in a different 90th percentile lead level.
For the remainder of the compliance periods, where differences in either 90th percentile
calculations and/or percentage of samples greater than the AL were calculated (July -
December 2003; January - June 2004; July - December 2004), the differences were
relatively minor and could be attributed to the number of valid samples, 90th percentile
calculations, or differences in hard copy tabular data versus Excel spreadsheet data. In
all of these compliance periods, both DCWASA and HDR/EES calculated 90th percentile
values above the AL.
14
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Table 3. Monitoring program for first-draw lead samples - comparisons of
DCWASA and HDR/EES calculations
Monitoring
Period
Jan - Jun
1992
Jul - Dec
1992
Jan -Jun
1993
Jul- Dec
1993
Jan -Jun
1994
Jul - Dec
1994
Jan -Jun
1997
Jul- Dec
1997
Jul- Dec
1998
Jan -Jun
1999
Jul-Sep
1999
Jul 2000-
Jun 2001
Jul 2000-
Jun 2001
(revised
calculations
-see 2.2.2)
Jul 2001 -
Jun 2002
Jan -Jun
2003
July- Dec
2003
Jan -Jun
2004
Jul- Dec
2004
DCWASA Results
N
129
125
114
131
114
115
112
115
108
106
55
50
52
53
104
108
108
130
90th
Percentile
Lead
(ug/L)
18
15
11
37
22
12
6
8
7
5
12
8
36
75
40
63
59
59
%
Samples
Lead
Cone.
> 15 |jg/L
12
10
4
21
14
7
4
4
4
6
5
8
17
49
26
32
68
31
HDR/EES Results
N
128
122
115
119
114
115
112
114
100
81
55
50
53
53
104
108
108
142
90th
Percentile
Lead
(ug/L)
18
39
11
29
14
12
6
8
7
<10
12
8
36
75
40
61
58
51
%
Samples
Lead
Cone.
> 15 ug/L
12
22
4
19
8
7
4
4
4
4
5
8
17
49
26
32
68
28
Reason for Different Results
One duplicate value removed. 90th
percentile result not affected.
Three duplicate values removed,
plus difference in other valid
samples used. 90th percentile result
affected.
One additional sample. 90th
percentile result not affected.
One triplicate and 11 duplicate
samples removed, plus difference in
total number of valid samples. 90th
percentile result affected.
Five data points not confirmed by
laboratory reports. 90th percentile
results affected.
NA
NA
One duplicate value removed. 90th
percentile result not affected.
Five duplicates and three raw water
samples removed. 90th percentile
result not affected.
Difference in total number of valid
samples and conversion from ppb to
mg/L. 90th percentile result affected.
NA
NA
One additional sample included.
90th percentile result not affected.
NA
NA
Difference in 90th percentile
calculation method. 90th percentile
result affected.
Difference in 90th percentile
calculation method. 90th percentile
result affected.
Difference in number of valid
samples due to difference in hard
copy versus Excel spreadsheet
data. 90th percentile result affected.
N = Number of samples used in 90th percentile calculation; NA = Not Applicable
Note: Bold: Values in bold font indicate differences between HDR/EES and DCWASA calculations.
15
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2.2.2 LCR 90th Percentile Reassessment
DCWASA met the lead AL of 15 |o,g/L per the LCR during compliance monitoring from
July 1994 through September 1999. As allowed by the LCR, in February 2000 USEPA
Region 3 reduced the requirement for LCR tap monitoring to once per year at 50 sites.
The DCWASA system continued the reduced monitoring through the July 2001 - June
2002 monitoring period, because DCWASA had reported an LCR 90th percentile value
below the AL during the July 2000 - June 2001 LCR monitoring period. In 2004, USEPA
Region 3 determined that DCWASA had not included all sample results in its original
90th percentile calculations for the July 2000 to June 2001 period. As listed in Table 3,
USEPA Region 3 recalculated the 90th percentile lead level for this monitoring period
using all sample results (Rizzo, 2005b). This reassessment showed that the 90th
percentile lead level during the July 2000 - June 2001 monitoring period was not 8 ug/L,
as originally reported by DCWASA, but it was actually higher at 36 ug/L, which exceeded
the AL.
2.3 Second-Draw Lead Results
DCWASA requested that homeowners collect second-draw samples from 1997 through
2004. For the 1997 monitoring periods, second-draw samples were collected and
analyzed, but 90th percentile values were not calculated or reported by DCWASA.
Second-draw sample results are not used for LCR compliance purposes; however, 90th
percentile lead values were calculated for comparison to the AL. HDR/EES reviewed
lead concentrations in second-draw samples, checked results against laboratory sample
reports, converted hard copy data to digital form, and calculated 90th percentile values.
The results of this analysis are summarized in Table 4. In summary, 90th percentile
calculations for second-draw samples were greater than 15 ug/L in the July - September
1999 monitoring period, and in every monitoring period from 2001 to 2004.
Differences in results were found for the following monitoring periods: July - December
1998; January - June 1999; January - June 2004; and July - December 2004. These
differences, highlighted in bold in Table 4, involve differences in total sample count
and/or numerical ordering of sample results in the 90th percentile calculations.
For example, in the July - December 1998 monitoring period, 99 second-draw samples
were collected. Therefore, the 90th percentile lead concentration should be equal to the
lead concentration of the 89th sample with samples listed in ascending order of lead
concentration. This 89th sample is equal to 7.0 ug/L; therefore, the 90th percentile lead
concentration is determined to be 7.0 ug/L compared with 6.6 ug/L calculated by
DCWASA. DCWASA did not provide details or documentation of the procedure used for
calculating the 90th percentile.
For the January - June 1999 period, laboratory sampling reports indicate that 15
second-draw samples had a lead concentration of "<10 ppb"; however, DCWASA's 90th
percentile calculations, which converted the data to mg/L, show no samples with a lead
concentration of <0.010 mg/L, which is equivalent to <10 ppb. One sample listed in
DCWASA's 90th percentile calculations (0.022 mg/L) could not be confirmed by the
laboratory sample reports. Also, DCWASA's 90th percentile calculations show a total of
105 second-draw samples, but the laboratory summary report indicates only 79 second-
draw samples. Thus, HDR/EES's calculation resulted in a different 90th percentile lead
level.
16
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Table 4. Monitoring program for second-draw lead samples - comparisons of
DCWASA and HDR/EES calculations
Monitoring
Period
Jan- Jun 1997
Jul-Dec1997
Jul-Dec1998
Jan- Jun 1999
Jul-Sep 1999
Jul 2000-Jun
2001
Jul 2000-Jun
2001 (revised
calculations by
USEPA Region
3)
Jul2001-Jun
2002
Jan- Jun 2003
Jul-Dec 2003
Jan- Jun 2004
Jul-Dec 2004
DCWASA Results
N
-
-
108
106
55
50
-
53
104
108
108
130
90th
Percentile
Lead
Cone.
(ug/L)
-
-
6.6
4
15
11
34
80
21
43
75
45
%
Samples
Lead
Cone.
> 15 |jg/L
-
-
3
4
9
6
15
46
17
27
60
28
HDR/EES Results
N
93
109
105
78
55
50
58
52
104
108
109
134
90th
Percentile
Lead Cone.
(ug/L)
7
7
7
<10
15
11
34
80
21
43
73
42
% Samples
Lead Cone.
> 15 ug/L
5
4
3
4
9
6
15
46
16
27
60
28
Reason for
Different Results
NA
NA
90th percentile
calculation
Number of valid
samples; data
conversion from
ppb to mg/L; one
data point not
confirmed by
laboratory report
NA
NA
NA
NA
NA
NA
Number of valid
samples
Unknown*
N = Number of samples used in 90th percentile calculation; NA = Not Applicable
Note: DCWASA did not calculate or report second-draw lead concentrations for the two monitoring periods in 1997.
*DCWASA's reported 90th percentiles were presented in a cover letter, but calculation details were not available.
Bold: Values in bold font indicate differences between HDR/EES and DCWASA calculations.
2.4 Designation of Optimal Corrosion Control Treatment
In July 1997, USEPA Region 3 conditionally designated OCCT as maintenance of a
slightly positive Langelier Saturation Index (LSI) through pH adjustment. As a condition
of this designation, USEPA Region 3 issued an Administrative Order requiring WA and
DCWASA to jointly assess the feasibility of alternative corrosion control treatment
including use of sodium hydroxide for pH control, and use of a non-zinc orthophosphate
corrosion inhibitor.
Modeling results from the caustic soda study (Malcolm Pirnie Inc., 1998a) indicated that
excessive calcium carbonate precipitation would occur if a pH of 8.5 was maintained
throughout the year using either lime or caustic soda. The study also concluded that
caustic soda would provide some benefits in terms of process control and maintenance
requirements. The corrosion inhibitor study (Malcolm Pirnie Inc., 1998b) concluded that
zinc orthophosphate would not provide any long-term benefits over orthophosphate in
17
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controlling lead levels in the water, and the chemical costs for zinc orthophosphate are
approximately twice the chemical costs for phosphoric acid. The corrosion inhibitor
study recommended that phosphoric acid be used at a dosage rate of 1.0 mg/L as
phosphate (PO4) if WA decided to use corrosion inhibitors as a lead control strategy.
On February 29, 2000, USEPA Region 3 designated the use of pH adjustment as the
OCCT for the systems served by WA. This designation required WA to maintain the
highest pH level attainable at the entry points to the distribution system without causing
excessive CaCO3 precipitation in the distribution system (USEPA, 2000).
USEPA Region 3 also designated Optimal Water Quality Parameters (OWQP),
including an enforceable minimum pH of 7.7ฑ0.3 to be maintained at the entry points to
the distribution system and at all tap sample locations. In response to this designation,
DCWASA and WA proposed modifications to the OWQP that would allow the minimum
finished water pH requirement to change monthly to account for seasonal water quality
changes in the Potomac River, as summarized in Table 5. DCWASA and WA also
proposed a change to the minimum pH requirement at distribution system sites from 7.7
to 7.0 (source: correspondence from DCWASA and WA, respectively, to USEPA Region 3
on May 1 and May 3, 2000). Two years later, on May 17, 2002, the USEPA revised
its designation of OWQP by approving WA's and DCWASA's proposal, and indicated the
effective date was retroactive to the monitoring period that began on July 1, 2000.
Table 5. Minimum required pH for distribution system entry points
Month
January
February
March
April
Minimum
PH
7.7
7.8
7.7
7.6
Month
May
June
July
August
Minimum
PH
7.5
7.4
7.4
7.4
Month
September
October
November
December
Minimum
PH
7.4
7.5
7.5
7.6
Figure 2 shows finished water pH at both distribution system entry points (Dalecarlia and
McMillan Water Treatment Plants) and the required minimum pH. The pH at the
Dalecarlia entry point has been below the established minimum pH only five times (<1%
of data collected) since the OWQP designation became effective July 1, 2000. The pH
at the McMillan entry point to the distribution system has been below the established
minimum pH only one time (<1% of data collected) since July 1, 2000. Finished water
pH levels routinely ranged from about 7.7 up to 8.5 and greater.
18
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Jul-00
Dec-00
Jun-01
Dec-01
Jun-02
Dec-02
Jun-03
Dec-03
Jun-04
Dec-04
Dalecarlia Plant
McMillan Plant ^Minimum pH required
Figure 2. Finished water pH compared to minimum required pH
at distribution system entry points (July 1, 2000 - June 30, 2004)
On April 30, 2004, USEPA Region 3 designated use of zinc orthophosphate for partial
system application in the 4th High Pressure Zone. This is a designated zone in
northwest Washington, D.C. that is hydraulically isolated from the rest of the distribution
system (USEPA, 2004b, 2006). On May 28, 2004, USEPA Region 3 modified the April
30, 2004 designation of OCCT to use orthophosphate instead of zinc orthophosphate for
the 4th High Pressure Zone.
On August 3, 2004, USEPA Region 3 modified the interim designation of OCCT for WA
and DCWASA to consist of application of orthophosphate system-wide, subject to stated
conditions and water quality parameters. The interim OCCT designation was slightly
modified and clarified on August 20, 2004 and September 8, 2004. USEPA Region 3
stipulated that, during the distribution system passivation period, WA was required to
meet a pH range of 7.7 ฑ 0.3 for finished water leaving both water treatment plants. A
goal of 7.7 ฑ0.1 was set, though this was not enforceable. For distribution system
samples, the same enforceable pH range (7.7 ฑ 0.3) and non-enforceable pH goal
(7.7 ฑ 0.1) was applied to DCWASA.
19
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Figure 3 shows the average distribution system pH at the 12 OWQP Monitoring Sites in
the DCWASA distribution system from July 1, 2000 through October 26, 2004. The 12
OWQP Monitoring Sites were identified by DCWASA in correspondence to USEPA
Region 3 dated May 1, 2000. For OWQP monitoring through the date of the USEPA's
designation of orthophosphate treatment (July 1, 2000 through August 3, 2004), results
show the minimum pH was 7.0, thus demonstrating compliance with the OWQP
minimum pH of 7.0. After designation of orthophosphate treatment, OWQP monitoring
results were reported through October 26, 2004. Where sufficient data are available, the
3-month running average is shown as a solid line in Figure 3.
9.0
7.0
6.5
Solid line = 3-month
running average
Jul-00 Dec-00 Jun-01 Dec-01 Jun-02 Dec-02 Jun-03 Dec-03 Jun-04 Dec-04
Figure 3. Average distribution system pH measured at different OWQP monitoring sites
over different time periods. (July 1, 2000 - October 26, 2004)
2.5 Lead Service Line Replacement Program
Since 2002, DCWASA has been required to replace 7% of the lead service lines on an
annual basis due to AL exceedance.
In September 2003, DCWASA updated its inventory of lead service lines and
estimated that of the system's 120,000 service connections, 23,071 were lead
service lines. On October 24, 2003, DCWASA reported that during the period
October 1, 2002 to September 20, 2003, it had replaced 385 lead service lines
through physical replacement including 79 "full" replacements and 306 "partial"
replacements (DCWASA Lead Service Replacement Program Annual Report for
2003; USEPA Region 3, June 17, 2004).
20
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A partial lead service line replacement (PLSLR) means that something other than the
entire length of the service line is replaced (Code of Federal Regulations, Title 40, ง
141.84(d)). Title 40 CFR ง141.84 requires that a public water system replace the
portion of the lead service line owned by the system, but does not require that the
system bear the cost of replacing portions of the line that the system does not own.
On October 8, 2004, DCWASA reported that it had replaced 1,793 lead service lines
for the period October 1, 2003 to September 30, 2004 (DCWASA Lead Service
Replacement Program Annual Report for 2004). No details were provided in the
2004 report on full versus partial replacements.
Full and partial lead service line replacements can disturb protective scales on pipes or
connected components and thus cause the release of lead. The full and partial lead
service line replacements that have been undertaken by DCWASA are not considered
major factors in elevated lead release during LCR compliance monitoring beginning July
2000 because the LSL replacement program did not commence until lead levels were
already elevated. DCWASA failed to meet the 90th percentile AL during July 2001
through December 2004, and the LSL replacement program was triggered by failure of
DCWASA to meet the 90th percentile AL. Accordingly, LSLs were replaced during the
timeframes of October 1, 2002 through September 30, 2003 and October 1, 2003
through September 30, 2004. Further evaluation of DCWASA's LSL replacement
program could help determine the extent to which lead service line replacement may
have contributed to elevated lead levels at overall or at individual consumers' taps during
later periods of exceedance.
Follow-up monitoring required by the LCR at monitoring locations during 2002 through
2004 may have recorded spikes or temporary elevated lead levels due to scale
disturbance, possibly exacerbated by cutting and replacement techniques (Wujek, 2005;
Boyd et al., 2004). Although not clear, the LCR definitions of Tier 1 sampling sites do not
appear to exclude partial LSL replacement sites from continuing as Tier 1 sampling sites
(40 ง141.86 (3), (i), (ii)). As such, the impact of the PLSLR program could have
contributed to elevated lead levels in compliance monitoring data during 2002 through
2004 if the PLSLR sites were used for subsequent compliance monitoring. Without
additional information, it is difficult to assess or disregard the effects of PLSLR
techniques on elevated lead levels overall or at individual homes where replacements
were made. Additional analyses of LSLR sites compared to compliance monitoring sites
during 2002 through 2004 would therefore be needed to determine if the LSLR program
affected compliance monitoring results at LCR monitoring locations.
21
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3. WATER TREATMENT FACILITIES
This section describes the following:
Water quality data collected at the two entry points to the distribution system.
Findings from 1999 and 2003 sanitary surveys of WA-owned facilities.
Data for analysis of water treatment facilities were compiled from daily water quality
monitoring results from the Dalecarlia and McMillan plants and from sanitary surveys of
WA and DCWASA facilities.
3.1 Water Quality at Distribution System Entry Points
WA collects daily samples for chlorine residual, temperature, pH, and alkalinity at the
two entry points to the distribution system located at the Dalecarlia and McMillan Water
Treatment Plants. HDR/EES reviewed water quality data from 1998 through mid-2004
with the exception of alkalinity data, which were not available for years 2000 - 2001.
The review of water quality data showed that the two water treatment plants produce
water with similar variations in temperature, pH, and alkalinity. As shown in Figure 4, the
pH of samples collected at the distribution system entry points generally varied
seasonally from 7.7 to 8.5. Figure 5 shows that alkalinity varies widely, typically ranging
from about 40 to 100 mg/L as CaCO3 in recent years. Water temperature, shown in
Figure 6, varies seasonally from about 35 to 85ฐF.
6.5
Jan-98 Jun-98 Dec-98 Jun-99 Dec-99 Jun-00 Dec-00 Jun-01 Dec-01 Jun-02 Dec-02 Jun-03 Dec-03 May-04 Nov-04
Dalecarlia
McMillan
Figure 4. Finished water pH measured at the distribution system entry points (1998
2004). Drought periods are designated using solid and dashed lines
22
-------
160
140
Jan-98 Jul-98 Feb-99 Aug-99 Mar-00 Sep-00 Apr-01 Nov-01 May-02 Dec-02 Jun-03 Jan-04 Jul-04
ADalecarlia O McMillan
Figure 5. Finished water alkalinity measured at the distribution system entry points (1998
2004; no alkalinity data was available for 2000 - 2001)
100 T-
&.
m .ifl
Jan-98 Jul-98 Feb-99 Aug-99 Mar-00 Sep-00 Apr-01 Nov-01 May-02 Dec-02 Jun-03 Jan-04 Jul-04
Dalecarlia McMillan
Figure 6. Finished water temperature at distribution system entry points (1998 - 2004)
23
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Figure 7 illustrates chlorine residuals for samples collected at the Dalecarlia and
McMillan plants for years 1998 - 2004. These data were provided electronically as
Excel spreadsheets. Results were reported as free chlorine prior to November 1, 2000
(disinfectant conversion) and as total chlorine afterward. Prior to the conversion, free
chlorine results indicate fluctuations ranging from approximately 2.2 to 3.2 mg/L. After
the conversion, chlorine residual increased and total chlorine measurements typically
ranged from 3.3 to 3.9 mg/L. Since fall 2003, total chlorine appears to have stabilized in
the typical range of 3.5 to 4.0 mg/L.
WA has analyzed the conductivity of untreated water on a monthly basis since 1999.
HDR/EES reviewed the available untreated water conductivity data from 1999 through
2002, as presented in Figure 8. Conductivity appears to vary seasonally, increasing in
the second half of each year and occurring at lower levels during the spring and early
summer. The average conductivity of the source water was 318 micromhos per
centimeter (1 micromhos per centimeter = 1 microsiemen per centimeter), and 3-month
average values ranged from 238 to 437 micromhos per centimeter.
3.2 Findings from Sanitary Surveys of Water Treatment Facilities
HDR/EES reviewed sanitary surveys of facilities owned by WA. The contents of the
sanitary surveys are described below.
The 1999 sanitary survey documented 73 potential sanitary risks, such as the need
for a comprehensive watershed protection program for the Dalecarlia Reservoir, and
for updating standard operating procedures for water treatment process operations.
At the time of the 2003 survey, 21 of these 73 potential sanitary risks had been fully
addressed; 11 had been partially addressed; 7 were no longer applicable to the WA
system; and 34 were not addressed.
The 2003 sanitary survey team identified 37 sanitary deficiencies, including 32 of the
45 sanitary risks identified in the 1999 survey that had not been addressed or only
partially addressed. These 37 sanitary deficiencies included development of a
comprehensive cross connection control program; development of a comprehensive
watershed protection program for the Dalecarlia Reservoir; updating of standard
operating procedures for water treatment process operations; an optimization
program for each water treatment plant (WTP) including detailed filter evaluations;
development of procedures to minimize hydraulic changes in filter operations during
backwash; and clearwell modifications to minimize vandalism and pathogen intrusion.
It is difficult to determine whether findings from these sanitary surveys had any influence
on tap lead levels. Further examination of pre-1999 sanitary survey data for water
treatment facilities may provide more information about events that preceded elevated
lead release. Sanitary survey results specific to the distribution system are also
discussed in Section 4 and include data prior to 1999.
24
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5.0 i
Disinfection using Free Chlorine
Disinfection using Chloramines
Jan-98 Jun-98 Dec-98 Jun-99 Dec-99 Jun-00 Dec-00 Jun-01 Dec-01 Jun-02 Dec-02 Jun-03 Dec-03 May-04
Dalecarlia
McMillan
Figure 7. Finished water chlorine residual concentration at distribution system entry
points (1998-2004)
500
450
Jan-98 Jul-98 Feb-99 Aug-99 Mar-00 Sep-00 Apr-01 Nov-01 May-02 Dec-02 Jun-03 Jan-04 Jul-04
A Untreated Water ^^3-month Average - Untreated Water
Figure 8. Specific conductance of untreated water (1998 - 2002)
25
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4. DISCUSSION OF DISTRIBUTION SYSTEM
CONDITIONS
This section discusses:
Conditions in the DCWASA distribution system from 1998 - 2004 including water
quality trends, lead sources, and other relevant findings from sanitary surveys.
Available data and information used to identify the major lead sources in or
connected to the distribution system.
4.1 Water Quality Trends
Water quality data collected in the distribution system are reported here as daily average
parameters for years 1998 through 2004. Data were provided either in digital format or
as hard copy laboratory reports or a combination of both. Data were provided in digital
format for pH, temperature, free and total chlorine, conductivity, and sampling location
for 2001 through 2004. Distribution system pH and alkalinity data were also provided in
hard copy reports for years 1998 to 2004. Data and sampling locations included in hard
copy reports were transcribed into Excel spreadsheets. Available data and information
were then combined into a single spreadsheet. Daily averages were calculated for each
parameter based on all available data by sampling location for the years 1998 through
2004. The total number of sampling locations varied by period and parameter; that is,
the average value for a given day could have been based on one sampling location or
15 locations, depending on available data. For sampling periods with both hard copy
and digital formats available, the digital format was used in this report.
Table 6 summarizes the sources of data and information that are discussed in Sections
4 and 5 of this report. Updated water quality data, sampling dates, and sampling
locations are included in the three-ring binders as supplemental information for this final
report.
Table 6. Sources of data and information for water quality parameters
Parameter
PH
Alkalinity
Temperature
Total chlorine
Conductivity
ORP
Hard Copy Reports a
8/3/98-12/18/00
8/3/98 - 6/30/04
8/3/98-12/18/00
8/3/98 - 6/30/04
4/5/04 - 7/6/04
Digital Format
3/2/01 -12/30/04
3/2/01 -12/30/04
3/2/01 -12/30/04
4/05/04 - 7/6/04
a. Hard copy reports were transcribed into Excel spreadsheets and merged with data provided in digital
format.
4.1.1 pH
Average daily pH and 3-month running average pH values are shown in Figure 9. The
line in Figure 9 represents 3-month average pH based on the average of all samples
collected during the previous month, the current month, and next month (i.e., the 3-
month average for June is the average pH for samples collected in May, June, and July).
26
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Breaks in the 3-month average plot line indicate periods when sufficient data was not
available to compute the 3-month average. The average daily pH appears to vary
seasonally, peaking in March or April annually except for 2002 and 2003. In late 2001
and early 2002, the distribution system pH was significantly lower than in other years,
with 3-month average pH values less than 7.5. In 2003, the peak pH value occurred in
early February. The average distribution system pH value for the 1998 through 2004
period was 7.8 with a range of 7.0 to 8.7. It is noteworthy that average pH levels in the
distribution system vary widely on a seasonal basis from as low as 7.0 - 7.2 to greater
than 8.5.
Solid line = 3-month
average
Jan-98 Aug-98 Mar-99 Oct-99 May-00 Jan-01 Aug-01 Mar-02 Oct-02 Jun-03 Jan-04 Aug-04
Figure 9. Average daily pH of water samples collected at various sampling sites within the
distribution system (1998 - 2004). The 3-month running average pH
in the distribution system is shown for comparison.
4.1.2 Alkalinity
As shown in Figure 10, the average daily alkalinity appeared to vary seasonally, peaking
during the winter months, until 2003. In 2003, the peak alkalinity level occurred in
August. During 2003 and 2004, the distribution system alkalinity decreased overall and
yielded an average of 68 mg/L as CaCO3 (note: alkalinity data do not indicate whether
measurements were reported as CaCO3- this has been assumed.) The average
distribution system alkalinity for samples collected from 1998 to mid-2004 is 78 mg/L as
CaCO3.
27
-------
160
Jan-98 Jul-98 Feb-99 Aug-99 Mar-00 Sep-00 Apr-01 Nov-01 May-02 Dec-02 Jun-03 Jan-04 Jul-04
A Distribution System Alkalinity ^^3-month Sample Average
Figure 10. Average daily alkalinity of water samples collected from various sampling sites
within the distribution system (1998 - 2004). The 3-month running average alkalinity value
in the distribution system is shown for comparison.
Average daily alkalinity and pH values are plotted as a function of time in Figure 11.
From the data reported in Figure 11 it is evident that periods of lower alkalinity in the
distribution system did not necessarily correspond to lower pH (more acidic) values. For
example, in March of 1999 through 2001 and March 2004 there were seasonally
associated spikes in pH (to approximately pH 8.5) which corresponded to drops in
alkalinity. From April to September 2002, during which the pH remained at a relatively
constant value of 7.3, the distribution system alkalinity had decreased from roughly 100
to 60 mg/L as CaCO3. However, the onset of changes in pH and alkalinity did not
correspond with one another, suggesting that alkalinity alone was not the principal
determinant in the lower pH values that were observed in the distribution system over
time.
4.1.3 Temperature
The average daily temperature for water in the distribution system is shown in Figure 12.
The temperature varied seasonally, fluctuating from a low of about 40 to 45ฐ F to a high
of about 80 to 85ฐ F and peaking in July to August every year.
28
-------
160
6.5
Dec-96 Sep-97 Jul-98 May-99 Mar-00 Jan-01 Nov-01 Sep-02 Jun-03 Apr-04 Feb-05 Dec-05
Figure 11. Average daily pH and alkalinity of water samples collected at various sampling
sites within the distribution system (1996 - 2004)
Jan-98 Jul-98 Feb-99 Aug-99 Mar-00 Sep-00 Apr-01 Nov-01 May-02 Dec-02 Jun-03 Jan-04 Jul-04
Figure 12. Average daily temperature of water collected from sampling sites within the
distribution system (2001 - 2004)
29
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4.1.4 Total Chlorine
WA converted from free chlorine to chloramines as a secondary disinfectant in
November 2000. Since implementing the disinfectant conversion, WA has switched
periodically from chloramines to free chlorine to address nitrification during the following
dates (Rizzo, 2006):
March 13 to May 13, 2002
March 10 to April 10, 2003
April 2 to May 7, 2004
These periods are referred to as temporary disinfectant changes for the purposes of this
report. Figure 13 shows average daily total chlorine data for water samples collected in
the distribution system in 2001 through 2004. Data collected during the temporary
disinfectant changes are highlighted in Figure 13. In general, data indicate that the total
chlorine residual in the distribution system during the temporary disinfectant changes
was dosed at the same levels as during chloramination.
I Temporary switch to free
chlorine
Mar-01 Aug-01 Feb-02 Aug-02 Feb-03 Aug-03 Feb-04 Aug-04
Figure 13. Average daily total chlorine concentration for water samples collected from
various sampling sites throughout the distribution system (2001 - 2004).
4.1.5 Conductivity
DCWASA reported values for specific conductance of water in the distribution system at
varying intervals and intermittently since 1997. HDR/EES included distribution system
data from 1998 through 2004. Available data are shown in Figure 14. Similar to data for
-------
untreated water (Figure 8), conductivity in the distribution system appears to vary
seasonally, increasing in the second half of each year and occurring at lower levels
during the spring and early summer. The average conductivity in the distribution system
is 355 micromhos per centimeter, and 3-month average values range from 218 to 495
micromhos per centimeter. The magnitude of these conductivity measurements is
comparable to the untreated source water.
550
500
- 450 -
I
01
u
J
u
3
o
c
o
O
o
'o
01
Q.
400
350 -
300 -
250 -
200
Solid line = moving
average
Jan-98 Jul-98 Feb-99 Aug-99 Mar-00 Sep-00 Apr-01 Nov-01 May-02 Dec-02 Jun-03 Jan-04 Jul-04
Figure 14. Average daily specific conductance for water samples collected from various
sampling sites throughout the distribution system (1998 - 2004). The 3-month running
average specific conductance for water in the distribution system is shown for
comparison.
4.2 Lead Sources
This section discusses available data and information that were used to identify possible
sources of lead in the DCWASA drinking water supply. Data and information collected
from the Potomac River were used to assess background lead levels in the natural water
source. Additional reports and limited data from samples collected directly from
distribution mains were used to assess lead levels in the distribution system. Lead
profiling data collected at homes were used to assess the contribution of lead service
lines and premise plumbing.
In 2003, DCWASA, with the assistance of Dr. Marc Edwards, developed and
implemented a data collection protocol to identify the lead profiles at individual homes.
This protocol was utilized at several homes throughout the city to determine the source
of lead, the form of the lead (dissolved or particulate), and lead concentrations within the
home, the service line, and the water main. Data from 28 lead profiles collected from
December 8, 2003 through July 6, 2004 were available for review and are displayed
31
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graphically in Appendix A (Moser, 2006). Additional profiles were provided later (Odom,
2006) covering the timeframe since orthophosphate inhibitor was implemented. These
additional profiles are included in Appendix A, but have not been analyzed in detail.
4.2.1 Lead Source Evaluation Using Lead Profiling
4.2.1.1 Lead Profiling - Methods and Approach
Twenty-eight lead profiles were developed for 19 homes. The sampling protocol called
for an initial sample to be collected in the morning after high water use (samples listed
as '0' or '00' on the profiles in Appendix A), followed by a 6 to 8 hour stagnation period
after which sequential 1 liter samples were collected at the tap (samples 1-20 for
example) (Giani et al., 2005a). In addition, some samples were collected after the final
sequential sample followed by a period of allowing the water to flow. For example,
samples listed as 25+3, etc. on the profiles indicate results from samples collected after
the water was allowed to run for 3 minutes after collecting the 25th liter. An additional
sample was collected after turning the faucet on and off several times over a 1-minute
period, then allowing the water to run 30 seconds prior to collection. Results from these
samples are indicated as "X" on the graphs in Appendix A and represent a water
hammer condition to evaluate detachment of particulate lead. DCWASA staff removed
aerators on taps prior to conducting these lead profiles (Rizzo, 2006c).
Depending on the length and diameter of in-house plumbing and the lead service line at
each site, lead results analyzed from selected 1-liter samples drawn from the kitchen tap
were correlated to one of the three types of piping based on the corresponding volumes.
For example, at one home, the first 4 liters of water withdrawn from the kitchen tap
represented the in-house plumbing; the 5th through 9th liters represented the lead
service line, and the 10th and additional liters represented the water main. Lead levels
were analyzed on liters 1, 2, and 4 (home piping); 5, 7, and 9 (lead service line); and on
liters 13, 17, 21, 25, and 45 (the main).
Of the 28 profiles, some were completed at the same houses during one or both
disinfectant regimes, and before and after events such as partial lead service line
replacement (PLSLR). Additional information is provided in Table 7.
32
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Table 7. Disinfection regime corresponding to when profile data was collected
at sites within the DCWASA system
Dates
Dec 2003-
Apr 1 , 2004
Apr 2, 2004-
May 7, 2004
May 18, Jun 28
and Jul 6, 2004
TOTAL
Disinfection
Regime
Chloramines
before
temporary
disinfectant
change
During
temporary
disinfectant
change
Chloramines
after temporary
disinfectant
change
Additional Information
No PLSLR
Repeat after PLSLR
During temporary disinfectant
change
Repeat of house profiled
during Chloramines and prior
temporary disinfectant change
Chloramines only
Repeat of house profiled
during Chloramines before
temporary disinfectant change
Number of
profiles
12
2
4
7
1
2
28
Figure 15 shows a typical profile that has been observed in the DCWASA system. The
time period corresponds to chloramine disinfection and is prior to addition of
orthophosphate inhibitor. The lead service line shows significantly higher lead levels
than both in-home plumbing and the distribution main. Results from profiling are
described in Section 5, and additional profiles are supplied both in Section 5 and
Appendix A.
11 14 17 20 24 29 29+3 29+10 00
I Total Lead
D Dissolved Lead
Figure 15. Lead profile for tap water samples from House #8
(sample collected March 9, 2004)
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4.2.1.2 Discussion of Results
Profiles from five homes connected to the DCWASA distribution system were discussed
by Giani et al. (2005a). The five homes had lead service lines and exceeded the 15-
ug/L AL of the LCR within the past 2 years. All of the profiles discussed by Giani et al.
(2005a) were collected during a period when chloramines were used for disinfection.
One of the homes discussed by Giani et al. (2005a) had lead profiles developed before
and after partial replacement of the lead service line. Overall findings from this study
indicate that the highest lead concentrations were observed in the water samples that
stagnated in the lead service line, compared with water samples representing in-house
plumbing and the water main.
Additional lead profiles were collected by DCWASA during chloramination and during the
temporary disinfectant change in 2004. Results are shown and discussed in later
sections of this report. Similar to the profiles discussed above, these additional profiles
collected before and after the temporary disinfectant change indicate that the lead
service line contributed the highest lead concentrations at the tap. Over 80% of the
profiles collected during these periods (chloramination and temporary disinfectant
change) displayed elevated lead levels from the service line portion of the sampling
profile.
Using 27 of the 28 profiles shown in Appendix A, an average concentration of lead
measured from each lead source (first liter [faucet and associated piping]; premise
[remainder of home plumbing]; lead service line; and main) was calculated. Information
on which sequential samples represented the first liter, remainder of premise piping, and
lead service line was contained in spreadsheets received from the USEPA (Moser,
2006). One set of profile data could not be used because it did not contain information
about which samples represented the premise piping, lead service line, and water main.
Table 8 presents the average lead concentration of the first liter (faucet and associated
piping), premise (remainder of home plumbing), LSL, and main, and the average mass
of lead attributed to these sources. The lead mass data is also represented graphically in
Figure 16. The data is presented separately for profiles during the temporary disinfectant
change and chloramination. The average mass of lead from the lead service line during
the temporary disinfectant change and chloramination were 157 and 470 ug,
respectively. In contrast, during the temporary disinfectant change and chloramination
the mass of lead in the first-liter sample (faucet and associated piping) was calculated to
be 21 and 26 ug, and the remaining home piping was 23 and 72 ug, respectively. The
mass of lead was not calculated for main samples since background lead levels in the
distribution system were assumed to be < 2 ug/L (Keefer and Giani 2005) and any lead
measured from these samples was likely due to pickup of lead from the lead service line.
Results shown in Table 8 and Figure 16 are not exact measurements of the lead
contribution of the lead service line, faucet, home piping, and main to lead levels
measured at the tap, but merely represent an average of lead released from each of
these sources. These results implicate lead service lines as the primary source of lead
measured at the tap, compared with lead release from premise plumbing and
components (e.g., solder and faucets).
34
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Table 8. Average lead concentration and mass for profiles during the temporary
disinfectant change (12 profiles) and chloramination (15 profiles)
Profiles Under the Influence of a Temporary Switch to Free Chlorine
Average
STD
Concentration, tig/l-
ist Liter
21
31
Premise
13
18
LSI
22
18
Main
6
4
Mass of Lead, |jg
1st Liter
21
31
Premise
23
22
LSL
157
141
Profiles Under the Influence of Chloramine Disinfection Only
Average
STD
Concentration, ug/L
26
15
31
18
73
50
23
27
Mass of Lead, |jg
26
15
72
44
470
271
a
1
I
o
o
m
in
ro
DFree Chlorine
Chloramines
First Liter
Premise
LSL
Figure 16. Average mass of lead contributed from various sources for profiles
experiencing a temporary switch to free chlorine and those exposed to chloramination
disinfection (unadjusted for actual volume of exposure).
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4.2.2 Source Water Lead Levels
Lead levels from Potomac River source water are frequently at the "no-detect" level, and
reported as less than 2 ug/L (Keefer and Giani, 2005). For the purposes of this report,
"source water" is defined as raw water from the Potomac River and "finished water" is
defined as treated water leaving the Dalecarlia or McMillan plants. Finished water lead
levels are presumably also at the non-detect level. This is difficult to confirm because
samples collected at the tap represent water that passed through the mains and was
possibly affected by additional lead uptake due to lead solubilization and release from
lead service lines and plumbing components.
4.2.3 Distribution Mains
Total lead level samples that are normally considered representative of water entering
the lead service line, were collected at the 28 profiles during the temporary disinfectant
change and chloramination. Samples included water drawn from the service connection
and plumbing and the distribution main in the DCWASA distribution system (labeled as
'0' or '00' on the profiles in Appendix A). The lead levels in these samples ranged from 1
to 115 |o,g/L, with an average total lead value of 16 |o,g/L. These samples were collected
in the morning after flushing the water, according to the procedure described in Giani et
al. (2005a), so presumably they represent water from the main. These values were
higher than expected based on negligible source and finished water lead levels. It can
be difficult to clearly identify lead contributions solely from the distribution main through
profiling, even with the appropriate flushing regime that yields samples representative of
the distribution main. It is the consultant's best professional judgment that lead profiling
data indicate the likelihood of continued dissolution and pick-up of lead from the service
connection including the lead service line and/or other lead sources between the main
and the tap and dispersion characteristics of premise piping systems, rather than a
notable lead source in the DCWASA water distribution system.
Studies on lead pipes with a range of exposure areas show that the initial rapid rate of
lead release is very important to overall lead levels. According to Fick's Law of Diffusion
and assuming an initial negligible lead concentration in water from the main, a large
concentration gradient can occur between the LSL and bulk water, thereby leading to
exponential rapid lead release, up to equilibrium solubility (Kirmeyer et al., 2000; Van
den Hoven et al., 1987). Stagnation time studies of lead pipes and lead-bearing brass
components (Lytle and Schock, 2000) also demonstrate rapid initial lead release.
Water samples collected directly from the distribution system provide a more reliable
indication of lead levels in the system. Average lead levels in water samples collected in
the distribution system are reportedly less than 2 ug/L (Keefer and Giani, 2005). In
water quality laboratory reports originating from the WA laboratory, supplied to
HDR/EES and characterized as distribution system data, lead data were not generally
reported. HDR/EES identified some isolated reports in which lead data were reported. It
is not clearly identified in all cases where samples were measured - some are cited as
taps and water meters and marked as type 'Sp', and one is identified as type 'Dist' and
lists lead level of 0.519 ug/L (June 13, 2001). This limited information, along with the
Keefer and Giani report (2005), suggests that water passing through the distribution
mains of the DCWASA system contributes minimally to lead levels at the tap.
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4.3 Findings from Sanitary Surveys in the Distribution System
HDR/EES reviewed recent sanitary surveys of the DCWASA system. A sanitary survey
was completed in 1995 to identify problems and develop recommended mitigation
measures associated with bacteriological activity in the distribution system. Survey
findings contained 185 recommendations, including a number of sanitary deficiencies at
distribution system reservoirs. Follow-up sanitary surveys were conducted in 1996,
1998, and 2002 to document progress on the 185 original recommendations from the
1995 survey, and to identify any additional needs. During this time, the distribution
system underwent major rehabilitation including inspection, cleaning, and rehabilitation
of storage facilities; cleaning of several large mains; development of a unidirectional
flushing program; new operation and maintenance (O&M) manuals; an improved Total
Coliform Rule (TCR) sampling plan and sampling sites; clearwell improvements; and
staff training. While it is possible that implementation of the unidirectional flushing
program and/or main cleaning may have impacted release of dissolved and particulate
lead from lead service lines connected to the distribution system, the extent of this
impact would be difficult to determine.
37
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5. CAUSATIVE FACTORS OF ELEVATED LEAD LEVELS
The purpose of this section is to identify and describe the evaluation of potential
causative factors that contributed to elevated lead levels in the Washington, D.C.
drinking water system. As used in this report, the term "causative factors" includes both
sources of lead and causative events. The term "causative events" includes historical
use of elevated free chlorine concentrations, changes in pH and pH variations, and
conversion from elevated free chlorine to chloramines.
HDR/EES reviewed, summarized, and evaluated the following data and information:
water quality data; LCR compliance data; sanitary survey reports; corrosion control study
reports; correspondence on OCCT; recently completed laboratory studies; lead profile
information; and information on DCWASA's lead service line replacement program.
These data, reports, and studies were used to identify and prioritize causes of elevated
lead levels in drinking water at consumers' taps in the DCWASA service area. The
following causative factors were considered for this evaluation:
Lead release from piping systems and other lead-bearing materials
Historical use of elevated free chlorine concentrations
Distribution system pH levels and pH variations
Conversion from elevated free chlorine to chloramines for final disinfection
Water quality characteristics in the distribution system
Galvanic corrosion of lead service lines
Effect of grounding currents on lead-bearing components
City-wide meter replacement program
Drought conditions and effects of corrosivity on DCWASA water
Section 5.1 discusses the integration of the potential causative factors listed above and
draws conclusions about the combination of factors that contributed to lead release at
consumers' taps in Washington, D.C. prior to the 2000 to 2004 LCR compliance
monitoring. Section 5.2 provides background information regarding oxidation reduction
potential, lead scales, theory, and ongoing research pertaining to the combination of
factors that can contribute to lead release in drinking water systems. Sections 5.3
through 5.11 provide separate evaluations of the causative factors listed above.
-------
5.1 Combination of Factors Contributed to Lead Release
A combination of factors - not a single source or a single causative event - contributed
to the problematic release of lead in water at consumers' taps in the DCWASA system.
Figure 1 in Section 1 illustrates the timeline of events beginning in 1992 that highlights
operations and regulatory compliance decisions, 90th percentile lead levels, shifts in
disinfectants and pH, coliform events, and other key dates and related activities. Table 9
provides a summary of decisions by USEPA pertaining to OCCT and actions by
DCWASA. The primary source of lead release was attributed to the presence of lead
service lines in the DCWASA service area. Since the mid-1990s, three notable
occurrences took place in the DCWASA system that likely contributed to elevated lead
releases during 2000 through 2004: (1) historical use of elevated free chlorine
concentrations; (2) low pH operating levels and pH variations; and (3) conversion from
elevated free chlorine to chloramines. These three notable occurrences pertained to
water quality changes and water quality conditions. Sources of lead and water quality
occurrences are summarized below.
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Table 9. Summary of Optimal Corrosion Control Treatment (OCCT) Decisions and
Actions
Date
OCCT Decisions and Actions
July 16, 1997
USEPA Region 3 designates OCCT as maintenance of a slightly
positive Langelier Saturation Index (LSI) through pH adjustment.
USEPA Region 3 issues an Administrative Order (AO) that the
above designation is subject to the condition that WA and
DCWASA jointly assess feasibility of alternate corrosion control
treatment including pH adjustment with sodium hydroxide and
addition of a non-zinc orthophosphate corrosion inhibitor.
February 29, 2000
As a result of the corrosion control feasibility studies, USEPA
Region 3 designated pH adjustment as the OCCT for the WA
distribution systems. This designation required that:
WA maintain highest pH attainable (without causing calcium
carbonate precipitation) at entry points to the distribution
system.
A minimum pH of 7.7 maintained at entry points to the
distribution system and at all tap samples within the
distribution system.
May 1,2000
DCWASA proposed modifications to the OCCT designation set by
USEPA Region 3. The modifications included the following:
Allow minimum pH requirement to change monthly to
account for seasonal changes (maximum of 7.8 in February
and minimum of 7.4 in June -September)
Reduce minimum pH in the distribution system from 7.7 to
7.0
May 17, 2002
USEPA revised its designation of OCCT to accept the
modifications proposed by DCWASA and WA on May 1, 2000
noting that the decision had been verbally agreed to in 2000. The
designation was made effective from the LCR monitoring period
which began on July 1, 2000.
April 30, 2004
USEPA Region 3 designated use of zinc orthophosphate for
partial system application in the 4th High Pressure Zone (a
hydraulically isolated zone of the DCWASA distribution system).
May 28, 2004
USEPA Region 3 modified the April 30, 2004 designation to use
orthophosphate, instead of zinc orthophosphate.
August 3, 2004
(modified Aug. 7,
Sept. 20, 2004)
USEPA Region 3 modified the interim designation of OCCT to
consist of the following:
Application of orthophosphate system-wide
Interim WQP
o WA pH 7.7 +/- 0.3 (entry points)
o DCWASA pH 7.7 +/- 0.3 (distribution system)
WQP Goal
o WA pH 7.7 +/- 0.1 (entry points)
o DCWASA pH 7.7 +/- 0.1 (distribution system)
40
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5.1.1 Sources of Lead
The primary source of lead release was attributed to the presence of LSLs in the
DCWASA service area. Faucets, lead-tin solder, and other home plumbing components
likely contributed, but were not the major sources of lead release in samples collected at
consumers' taps.
5.1.2 Historical Use of Elevated Free Chlorine
The first notable water quality change occurred in the mid-1990s when the concentration
of residual free chlorine was increased to the range of 2.2 to 3.2 mg/L, which was
implemented for the purpose of controlling coliform occurrence in the water distribution
system. These relatively high free chlorine concentrations likely facilitated the formation
of Pb (IV) scales in the form of lead dioxide (PbO2) in lead service pipes. Lead dioxide
scales generally exhibit relatively low lead solubility under normal ranges of pH and
alkalinity in public water systems when compared to Pb (II) compounds. Lead scales on
the interior of lead service lines are likely comprised of various forms of lead, including
both Pb (II) and Pb (IV), and the chemical composition of the scales likely changes with
varying water quality conditions.
5.1.3 Low pH Operating Levels and pH Variations
The second notable occurrence pertains to the fluctuating and low pH of the water
supply in the DCWASA system. pH of the water is an important factor in the control of
lead solubility. The pH of the distributed water in Washington, D.C. exhibited seasonal
variations that fluctuated from approximately 7.0 to 8.9 during 1992 to 2004. pH levels
at the lower end of this range would not be considered optimal for lead corrosion control
based on the conventional understanding of lead solubility per the LCR, which assumes
that the dominant form of scales is Pb (II). In Washington, D.C., however, and as stated
above, relatively high free chlorine concentrations during the mid-1990s likely facilitated
the formation of Pb (IV) as the dominant scale, which exhibits relatively low lead solubility
at the lower pH levels experienced in the DCWASA system.
5.1.4 Conversion from Elevated Free Chlorine to Chloramines
The third notable water quality change occurred when WA converted the residual
disinfectant from free chlorine to chloramines beginning November 1, 2000. The
residual disinfectant conversion was implemented for the purpose of lowering
disinfection byproducts to meet new regulatory requirements. This conversion facilitated
a reduction in ORP to a range that favors the predominance of Pb (II) scales. Pb (II)
species generally are highly influenced by low and fluctuating pH levels. This
conversion from free chlorine to chloramines likely facilitated the release of lead in water
while operating at low, fluctuating pH conditions. Lead release may also have been
impacted when the minimum pH requirements at entry points and distribution sites were
lowered at the request of WA and DCWASA and the request was approved by USEPA
Region 3 effective July 1, 2000.
5.2 Lead Scales and Solubility
As previously mentioned, it is likely that the lead scales on the interior of lead service
lines are comprised of various forms of lead, including both Pb (II) and Pb (IV). It is also
41
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likely that the chemical composition of these scales changes with varying water quality
conditions. Pb (II) scales, the dominant form of scales expected in public water systems
based on conventional understanding per the LCR, are highly influenced by low and
fluctuating pH levels. Pb (IV) scales, which can be formed in unique situations such as
elevated free chlorine concentrations, exhibit relatively low lead solubility under normal
ranges of pH and alkalinity in public water systems when compared with Pb (II) scales.
5.2.1 Oxidation Reduction Potential (ORP)
Oxidation reduction potential (ORP) is defined as the potential required to transfer
electrons from an oxidant to a reductant (Symons et al., 2000). Recent research on lead
corrosion shows that the bulk ORP value of water can increase in the presence of free
chlorine compared to chloramines. Lytle and Schock (2005b) noted that where lead-
bearing materials are present, Pb (IV) in the form of PbO2 is "associated with waters of
persistently high ORP". The authors note that the high ORP is a result of maintaining a
sufficiently high level of free chlorine residual whether due to low oxidant demand or
where high free chlorine concentrations are necessary to address microbiological
concerns in the distribution system. In lead precipitation experiments, Lytle and Schock
(2005b) found that at a maximum free chlorine residual dose of 3 mg/L, the ORP was
approximately 0.942 V corrected to the Standard Hydrogen Electrode (SHE), and when
the study concluded and free chlorine was 0 mg/L, ORP was approximately 0.440V
(SHE). Vasquez et al. (2006) evaluated several different source waters under different
treatment regimes and found ORP was higher in waters with free chlorine (0.9 V) than in
waters with chloramines (0.68 V). Switzer et al. (2006) measured equilibrium potentials
for free chlorine and monochloramine resulting in ORP of 1.02 V and 0.65 V,
respectively. Research also demonstrates that ORP can influence the dominant lead
species, (Lytle and Schock, 2005b; Switzer et al., 2006). Further, ORP is influenced by
several factors including the following: pH (Lytle and Schock, 2005b), temperature
(Vasquez et al., 2006), chlorine residual and concentration (Vasquez et al., 2006), and
dissolved oxygen concentration (Khanal et al., 2003).
Some ORP data were available for the DCWASA distribution system. Hydrant sampling
was conducted by DCWASA in 2004 at sites within the 4th High Pressure Zone, a
designated zone in northwest Washington, D.C. that is hydraulically isolated from the
rest of the distribution system (USEPA, 2004b, 2006). Hydrant sampling was conducted
during a period of temporary disinfectant change to free chlorine (April 1, 2004 through
May 7, 2004) and after converting back to chloramines (Odom, 2006b). Only two
hydrant sites were sampled during both periods. However, all data from the 4th High
Pressure Zone hydrant sampling, even where only one value was available, are plotted
in Figure 17.
Information was not available for this study regarding whether the ORP data in Figure 17
were reported as field data or if the ORP values were corrected to the standard
hydrogen electrode (SHE). Furthermore, the limited available data were evaluated for
the purpose of characterizing a relative difference in ORP during chlorination compared
to chloramination in the DCWASA system. The limited data appear to show higher ORP
values during a temporary change in disinfectant to free chlorine compared to the
subsequent return to use of chloramines in the DCWASA system.
As demonstrated in Figure 17, ORP levels were at least 150 mV higher during the
temporary change to free chlorine compared to periods when chloramines were in use.
During the temporary disinfectant change to free chlorine, the measured ORP values
42
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were > 650 mV. After the temporary disinfectant change, and a return to chloramines,
most sites showed an ORP in the 450 to 500 mV range.
Theoretical calculations of ORP based on other available parameters may also be
helpful in understanding historical redox conditions in the DCWASA service area
900
850
800
750
700
650
600
550
500
450
.5
Temporary switch to
free chlorine
4th high pressure zone
orthophosphate
application
V
J*
^
32nd & Rittenhouse St.
Tenley Circle&Yuma St.
38th&Fulton St
39th&Yuma St
49th SGIenbrook St
Nebraska & Mass Ave
-AReno & Upton St
-33rd & Upland Terrace
-O38th&Rodman
- O - - 45th SCathedral Ave
-4H-1 dn7-11 4313 Wisconsin Ave
Figure 17. ORP (mV) vs. date for the 4th High Pressure Zone during the temporary
disinfectant change (April 2, 2004 through May 7, 2004) and after the temporary
disinfectant change
For the data shown in Figure 17, there are no applicable lead data from the same
hydrant samples to correlate before, during, and after the temporary disinfectant change.
However, system-wide data collected before, during, and after the temporary disinfectant
change exists in the form of both LCR data (Table 3) and lead profiles from houses
(Section 5 and Appendix A). The LCR data in Table 3, although somewhat limited,
indicates that lead levels measured during the temporary disinfectant change using free
chlorine were lower than lead levels measured afterward during routine chloramination in
the DCWASA system.
The lead profile data in Section 5.6 for periods before and during the temporary
disinfectant change generally show a reduction in lead release during the temporary
disinfectant change. As shown in Figure 17, ORP data plotted after June 1, 2004 were
collected in the 4th High Pressure Zone during the partial system orthophosphate
application (Appendix A). Lead levels from samples collected after orthophosphate
application were not evaluated as part of this report. However, current LCR compliance
results suggest that lead levels have been effectively reduced by the addition of
orthophosphate inhibitor to the water supply (DCWASA, 2005, 2006).
43
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5.2.2 Lead Scales
Control of lead in drinking water generally has been presumed to be controlled by Pb (II)
solids that form on lead-containing materials. However, more recent evaluations of
scale materials on lead service lines have indicated the presence of Pb (IV) in the form of
PbO2 solids under certain distributed water quality conditions (Schock et al., 2001;
Schock and Giani, 2004; Schock, 2005; Schock et al., 2005). In theory, Pb (IV) solids
have a lower solubility than Pb (II) carbonate solids and will be stable in waters that have
a high ORP. Evidence has been gathered that Pb (IV) is formed under high ORP
conditions but it becomes unstable once ORP is lowered, and that the absence of a high
free chlorine residual (such as during chloramination) allows the occurrence of lower
ORPs (Schock and Giani, 2004; Lytle and Schock, 2005b). Therefore, by switching to
chloramines, the ORP of the water may be lowered, allowing Pb (IV) solids to
decompose via several possible reaction pathways. During the transformation, lead
levels in the water may increase and the more soluble Pb (II) carbonate species may be
formed as described by Schock and Giani (2004).
Figure 18 illustrates the electrochemical (EC) potential-pH diagram that is helpful in
understanding lead release events (Schock and Giani, 2004; Lytle and Schock, 2005b).
The numbered boxes show how the sequence of treatment changes formed the PbO2
passivating film associated with Pb (IV) during elevated free chlorine concentrations, and
then destabilized the Pb (IV) species when the pipe scales reverted to the predominance
of Pb (II) species during subsequent chloramination in the DCWASA system.
Point 1 (Figure 18) corresponds to a period in the early 1990s of low free chlorine
residual, Pb (II) scale dominance, and lead release problems. Initiation of high free
chlorine residuals and flushing in 1994 moved the system chemistry to the
predominance of Pb (IV) scales (PbO2) as shown by Point 2. The change to
chloramines for secondary disinfection on November 1, 2000 moved the ORP back into
approximately the area of Point 3, thus causing further lead species transformation back
to Pb (II) and an increase in lead levels at the tap. The DCWASA LCR lead level results
described previously and the reported analyses of scales on excavated lead service
lines support this mechanism. Lead service lines that were excavated prior to the
conversion to chloramination (i.e., lead pipes exposed to water when elevated levels of
free chlorine were used) primarily contained Pb (IV) compounds (plattnerite and
scrutinyite) with only traces of Pb (II) compounds (cerussite and hydrocerussite) (Schock
and Giani, 2004; Schock, 2005).
As demonstrated by theory and recent research, free chlorine residual levels can impact
lead release depending on the dominant form of lead, i.e., Pb (IV) or Pb (II), in scales on
lead service pipes. Additional data and discussion regarding free chlorine residual levels
in the DCWASA distribution system are presented in Section 5.4.
44
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1.SO
EMF-pH Digram for Pb-H2O-CO2 System
Pb species = 0.015mg/L; DIC=18mg C/L;
l(ionic stength) =0; T= 25"C
',' '; ' F1S, , ' , JWi
'. I, .'I ซ;j. !\ r-i 'i'ri r !'- V i.Ki ill I i I i . rA.M I . i i i . i i K.KXj
10 11 12 13 14
Figure 18. Potential-pH diagram for the lead system corresponding to DC WASA water
(Schock and Giani, 2004)
Conditions of low free chlorine residuals during the early 1990s and chloramines since
2000 suggest the possibility of similar ORP values in the DCWASA system and similarly
the predominance of Pb (II) scales as proposed by Schock and Giani (2004). The
solubility of Pb (II) is reasonably well established and believed much higher than Pb (IV)
over the normal range of pH in public water systems. However, current understanding of
Pb (IV) solubility is largely based on solubility models, and additional data gaps exist with
respect to alkalinity/DIC and other water quality parameters.
The effectiveness of orthophosphate in conditions whereby Pb (IV) scales are the
predominant species is not well understood. If an orthophosphate inhibitor had been
added to the DCWASA water supply for corrosion control in the early 1990s when Pb (II)
was presumably dominant, it may have been more effective as OCCT (than pH
adjustment) before, during, and following the switch from free chlorine to chloramines for
final disinfection. If orthophosphate treatment was used as OCCT in the early 1990s,
DCWASA may have avoided elevated lead levels in customers' taps. However, if an
orthophosphate inhibitor had been added to the DCWASA water supply during the mid
to late 1990s when elevated free chlorine was added to the water supply, then it is not
known how effective the orthophosphate inhibitor would have been compared to pH
adjustment. Currently, little information is available regarding the effectiveness of
orthophosphate treatment under Pb (IV) scale conditions, which are presumed to have
been dominant due to elevated free chlorine concentrations before the disinfectant
switch. Accordingly, this topic could benefit from further research to better understand
the impact of orthophosphate inhibitor under different disinfectant, ORP, and scale
conditions.
45
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It is important to point out that changing from free chlorine to chloramine disinfection
does not always correspond to elevated lead release. Pb (IV) formation is associated
with systems that have high ORP, which can be caused by a variety of mechanisms
including high free chlorine dosages (Schock and Giani, 2004). Free chlorine residual
levels are discussed further in Section 5.4.
Systems that do not have a history of such high ORP conditions may have maintained a
Pb (II) scale and never have been in a Pb (IV) regime. The accepted corrosion control
mechanism, based on Pb (II) and optimal corrosion control including pH adjustments,
would have been effective in those systems, and possibly not altered by chloramines,
since Pb (II) scale was already dominant as the passivating layer. Follow-on work with
other systems that have had disinfectant changes in the presence of Pb (IV) scales could
provide additional insight with regard to understanding the complex interrelationship of
lead scales and water quality.
5.2.3 Theory and Ongoing Research Pertaining to Pb (IV)
Theory and developing research on tetravalent lead can potentially improve
understanding of the treatment changes and conditions that influence lead scales and
lead release. As more information becomes available, it may further explain the
causative factors for the increased lead release in the DCWASA system.
According to recent studies (Lytle and Schock, 2005a; Switzer et al., 2006),
transformation of elemental lead, Pb(0), to divalent lead, Pb (II), occurs in both
chloraminated and chlorinated water systems. The transformation of existing Pb (II) to
Pb (IV) is not well understood beyond the presence and absence of free chlorine and the
corresponding measured ORP values. Similarly, details of the dissolution and
precipitation behavior of Pb (IV) are still not well understood (Lytle and Schock, 2005b;
Switzer etal., 2006).
Solubility differences between Pb (II) and Pb (IV) may also be important. The solubility
constants (Ksp) of PbO2, Pb3(OH)2(CO3)2 (hydrocerrussite) and PbCO3 (cerussite) at
10-66 10-is.8 and 10-is respective^ (Switzer et al., 2006; Marani et al., 1995) allow
calculations that show PbO2 is much less soluble than Pb (II) solids. This comparison of
solubility constants indicates that PbO2 potentially dissolves less readily than the two
Pb (II) mineral forms. Although speciation and solubility data for all of the various Pb (II)
and Pb (IV) compounds that may be involved is scarce, models suggest that Pb (IV)
solubility is generally lower than Pb (II) solubility (Schock et al., 2001).
In the Schock et al. (2001) study, lead scales from pipes in the Cincinnati distribution
system were examined using several mineral characterization techniques. The study
identified a passivating film consisting of polymorphs of Pb (IV) in the form of PbO2 on all
of the pipe samples. In the study, solubility vs. pH relationships were developed for
PbO2 using three values of the Gibb's free energy of formation obtained from the
literature. The solubility-pH relationships all predict that PbO2 has a much lower
solubility than Pb (II) in the form of PbCO3 and that the solubility of Pb (IV) in the form of
PbO2 decreases with decreasing pH. The authors note that the solubility-pH
minimization trend for Pb (IV) is the opposite of that for Pb (II); i.e., Pb (IV) solubility tends
to decrease with decreasing pH, approaching a minimum solubility at approximately pH
4. Based on these models, a change to a much more soluble form of lead (i.e., Pb (II)
mineral forms) offers a potential explanation for the sustained increase in lead release in
the DCWASA system. The earlier predominance of the relatively low solubility Pb (IV)
46
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could explain why the lower pH range did not adversely affect lead levels in that time
period, as might have been expected based on Pb (II) solubility. Under these
assumptions, the switch to chloramines in November 2000 and the reduction in minimum
allowable distribution system pH are conditions that would likely not have been optimal
for the Pb (II) scales.
5.3 Lead Release from Piping Systems and Other Lead-Bearing
Materials
Lead from piping can potentially be released in either the soluble or particulate form.
While particulate lead is important and can contribute to elevated lead in some
instances, soluble lead appears to be the primary form of lead measured in DCWASA
tap samples. The predominant source of soluble lead in the DCWASA tap samples is
attributed to lead service lines. Other components, fittings and piping materials made of
lead-bearing materials such as brass, bronze and solder potentially can contribute to
elevated lead levels at consumers' taps. These sources of lead are discussed below.
5.3.1 Soluble Lead from Piping
Figure 19 was developed by evaluating a specific sample from the lead profile data
(Section 5.2 and Appendix A) for every available profile and calculating the average
particulate and dissolved lead concentrations as a percentage of total lead. This
process was repeated for the 5th through 9th liters, which correspond to the lead service
line. Profiles were restricted to those collected during disinfection with chloramines from
December 8, 2003 through March 31, 2004. Profiles at sites with partial lead service line
replacements were omitted due to erratic results from particulate lead spikes. The
results listed below clearly show the predominance of soluble lead over particulate lead.
47
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Participate
Soluble
n = number of
samples used to
calculate the
average
5th liter (n = 10)
6th liter (n = 7)
7l" liter (n = 8)
Figure 19. Average contribution of dissolved and particulate lead
as a percentage of the total lead concentration in distribution system water
samples (December 2003 through March 2004)
Figure 19 shows soluble lead in the approximate range of 86 to 90 percent based on
HDR/EES's review of available lead profiles. This observation is consistent with findings
reported by Giani et al. (2005a) regarding lead levels in unfiltered and filtered samples
collected for lead profiling at five homes in the DCWASA system. In the study, the
filtered sample represents the amount of dissolved lead in the water, while the unfiltered
sample represents the total lead in the water. The conclusions of the Giani et al.
(2005a) study were that the majority of elevated lead concentrations were due to
dissolved lead, and the lead profiles presented, similar to HDR/EES's review, show that
approximately 85 to 90 percent of the total lead was in dissolved form. Based on these
findings, the detachment of lead particles from piping systems does not appear to be a
significant cause of elevated lead levels in the DCWASA system. Both the profiles
evaluated by HDR/EES and in the Giani study suggest that soluble lead is much more
important in terms of relative contribution to lead levels at consumers' taps.
5.3.2 Particulate Lead from Piping
Based on the results from the lead profiles, it appears that particulate lead release from
piping systems is not a significant system-wide problem with respect to samples
collected for LCR compliance, but may occur intermittently due to site-specific conditions
and hydraulics.
48
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The potential exists for lead particles (scale) to be disturbed and to detach from pipe
surfaces including in-house plumbing and lead service lines. Release of particulate lead
could be caused by a variety of factors, including hydraulic scour, physical disturbance
such as vibration (which could occur during service line replacement), chemical changes
in the water that might exacerbate release of particulate lead, and/or site-specific flow,
piping, and environmental conditions.
There are limited situations where high-particulate lead was measured in the DCWASA
service area. For example, the first sample from Profile #22, as illustrated in Figure 20
shows a relatively high concentration of total lead. Typically, the majority of total lead is
in dissolved form. However, high-particulate lead may be observed occasionally as
related to site-specific piping, water use patterns, or high flow rate during sample
collection that can cause shearing of particulate lead from the piping system.
180
160 -
140 -
120 -
ง. 100
S 80
60 -
40 -
20 -
0
In-house
Plumbing
Lead
Serivce Line
Main
2 3 5 7 9 10 11 13 15 18 21 24 27 27+327+10 0 X
Liter
I Total Lead D Dissolved Lead
Figure 20. Lead profile data for House #22 (sample collected April 30, 2004) under
conditions of water hammer that cause high levels of particulate lead release
(Particulate Lead = Total Lead - Soluble Lead)
The majority of the samples collected to evaluate water hammer effects (Sample 'X' in
Appendix A) exhibited high dissolved lead levels, i.e., little particulate lead. However, at
Profiles #16, #17, #22, #23 (Appendix A) the water hammer condition likely dislodged
particulate lead, indicating that occurrence of particulate lead may be related to hydraulic
conditions.
In a report to USEPA Region 3, Dr. Marc Edwards (Edwards, 2003) noted that LCR
sampling results may not take into consideration use of filtration devices on kitchen taps
and that sampling procedures at these sites should be checked and documented. Since
49
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2004, DCWASA's LCR sampling instructions have directed homeowners to remove
water filters from the sampling tap before taking the sample or to collect the sample from
a tap which does not have a filter (Rizzo, 2004).
A common configuration for faucets includes an aerator attached to the end of the
faucet. This aerator may serve as a trap for particulate lead that has been released from
piping systems. During June 2002 (the last month of the July 1, 2001 through June 30,
2002 compliance monitoring period), customers were instructed to remove the aerators
prior to collecting samples. The instructions for removing the devices prior to sampling
continued through the January 1 to June 30, 2003 monitoring period. From July 1 to
December 31, 2003, customers were instructed to leave the aerators in for lead
monitoring samples, and this procedure is still in effect (Smith, 2006). The impact of
leaving the aerator in place during sampling is that lead particles may be trapped in the
aerator rather than included in the sample. If these particles build up, they could provide
an additional lead source to the water. A sample drawn for compliance purposes from a
tap where the aerator is still in place would more likely represent human exposure
conditions.
With respect to particulate lead release from lead service lines, it is possible that partial
replacement of lead service lines could result in release of lead scale and cause a
corresponding increase in particulate lead measured at the tap. Since 2002, DCWASA
has been required to replace 7% of the lead service lines on an annual basis due to lead
action level exceedances. Wujek (2005) reported that particles in the remaining partial
lead service line piping were disturbed and released to the water column for a temporary
period of time after the replacement. While partial lead service line replacements may
have negatively impacted lead levels in the DCWASA system (i.e., due to the possible
release of lead particles to the water column) the extent of the impact cannot be
determined based on current information.
50
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Table 10 summarizes the evaluation of data and information regarding lead release from
piping systems.
Table 10. Summary evaluation of data and information -
lead release from piping systems
Data and Information
Considered
Evaluation of Data and Information as
Pertaining to this Possible Cause
HDR/EES analysis of DCWASA
Lead Profiles in Excel spreadsheet
obtained from USEPA Region 3.
Giani etal., 2005a.
Lead service line piping is the predominant source of lead
measured at the tap.
Approximately 86-90% of total lead is in the soluble form.
Approximately 85-90% (calculated by HDR/EES from
graphs in paper) of the total lead is in the soluble form.
Particulate lead occurs in limited instances, likely related to
site-specific piping and water use, and/or flow rate during
sample collection.
5.3.3 Faucets, Solder, and Other Home Plumbing
Typical plumbing and premise piping in residences and buildings can consist of lead-
bearing materials such as brass or bronze fittings and components and tin-lead solder
used to join copper piping. End-use devices such as faucets and plumbing fixtures also
can contain lead-bearing materials that can contribute to lead uptake in the water. Prior
to the promulgation of the Lead and Copper Rule in 1991, lead solder and flux used to
join copper premise piping and faucets and fixtures comprised of brass were shown to
be major sources of lead in tap water (Samuels and Meranger, 1984; Schock and Neff,
1988; Gardels and Sorg, 1989; AwwaRF, 1990; USEPA, 1991).
Giani et al. (2005a) evaluated the primary source of lead in the DCWASA system using
lead profile data collected at five homes. This study indicated that the highest lead
concentrations were observed in the water samples which stagnated in the lead service
line compared with water samples representing in-house plumbing and the water main.
Results from additional lead profiles also indicate that the lead service line contributes
the highest lead concentrations at the tap. Over 80% of the profiles available for review
in this study displayed elevated lead levels from the service line portion of the sampling.
An estimate of the relative mass of lead from faucets, solder, and other home plumbing
indicates that approximately 24 u,g of lead may be associated with the first liter sample
(faucet and associated piping) and 50 u,g of lead may be associated with the remaining
home piping and components prior to the lead service line. In the DCWASA system, as
in other analogous systems, whether lead service lines are present or not, other
plumbing components can still potentially result in exceedance of the LCR 90th percentile
AL at the consumers tap (Boyd et al., 2006b).
51
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As discussed previously in Section 4.2, the average mass of lead release attributed to
the LSL was 157 u,g during the temporary disinfectant change to free chlorine and 470
u,g during routine chloramination (Table 8). It is important to reiterate that these values
are based on average mass loadings of each source in the system. Based on results
from Giani et al. (2005a) and estimates of the mass loading of lead from various portions
of home and service piping, it appears that while faucets, solder, and other home
plumbing contribute to lead levels measured at the tap, they are not the predominant
source of lead in the DCWASA system. Table 11 contains a summary of the data and
information related to faucets, solder, and other home plumbing.
Table 11. Summary evaluation of data and information -faucets, solder, and other
home plumbing
Data and Information Considered
Evaluation of Data and Information
Pertaining to this Possible Cause
Giani etal., 2005a.
HDR/EES analysis of DCWASA Lead Profiles in
Excel spreadsheet obtained from USEPA Region
3.
Faucets, solder, and home piping contribute to lead
at the tap, but they are not the predominant source.
5.3.4 Distribution Mains
As discussed in Section 4.2, the distribution mains and other system components
connected to the DCWASA distribution system are not likely a major contributing source
of lead at the tap. While review of the lead profile data contained numerous instances
where thoroughly flushed samples from the water main still contain measurable lead, it is
likely, as explained in Section 4.2, that rapid release of lead from the lead service line
and/or home systems or dispersion and mixing characteristics of the premise plumbing
caused the higher than expected results in the flushed samples. Even without
acknowledging the rapid release from LSLs or other components, the results from water
in the main are still notably lower in the lead profiles than in the lead service lines. Table
12 summarizes the evaluation of data and information regarding water in distribution
mains.
Table 12. Summary evaluation of data and information -
water in distribution mains
Data and Information Considered
Evaluation of Data and Information
Pertaining to this Possible Cause
Keeferand Giani, 2005
Lead Profiles
Lead levels in the distribution system are low,
typically <2 ug/L.
Lead in flushed samples and in samples
targeting the main is often detectable and
many samples are greater than 10 ug/L, likely
due to rapid release of lead from service and
premise piping.
52
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5.4 Impacts of Historical Use of Elevated Free Chlorine
Concentrations
Chlorine residual data from the DCWASA entry points and distribution system locations
were provided for review. Data from the points of entry to the distribution system include
free chlorine measurements from January 1992 to October 2000, and total chlorine
residual measurements from November 2000 (after the switch to chloramines) through
December 2004. These data are shown in Figure 21.
To address Total Coliform Rule (TCR) problems in the distribution system in the early to
mid-1990s the free chlorine residual was increased from approximately 1-2 mg/L to 3 -
4 mg/L at entry points to the distribution system. As discussed previously in Section 5.2,
this lower chlorine residual period was thought to correspond to low ORP and
predominance of Pb (II) scales (Schock and Giani, 2004). Figure 21 shows the periods
of lower free chlorine residual at the distribution system entry points in the early 1990s
when lead release problems were first observed. Corresponding free chlorine levels
within the distribution system prior to 1998 were not available for review, but it can be
assumed that residual levels within the distribution system would have been lower than
those measured at the point of entry. The 1994 -1995 period of elevated free chlorine
residuals, and up until chloramination in November of 2000, were periods of low lead
release - thought to correspond to higher ORP and Pb (IV) scale dominance (Schock
and Giani, 2004).
Figure 22 shows free chlorine residual levels measured within the distribution system
from 1998 through 2004, which captures the period before and after the switch to
chloramines. Prior to the switch to chloramines and during the period of low lead
release (i.e., 1994 to October of 2000), free chlorine levels were approximately 2 mg/L
within the distribution system. As expected, after the switch to chloramines, the free
chlorine residual decreased to very low levels (i.e., typically less than 0.5 mg/L), aside
from seasonal switches back to free chlorine for nitrification control/prevention purposes.
The decrease in free chlorine levels associated with the switch to chloramination may
have created ORP conditions that were similar to the early 1990s when free chlorine
residuals were also relatively low and Pb (II) scales were thought to be dominant. As
described previously in Section 5.2, the operating pH was also reduced in July of 2000,
which may have contributed further to Pb (II) release under chloraminating conditions.
-------
Higher minimum free chlorine residual
Administrative Orders Issued by
USEPA Region 3 requiring
flushing and Improved
disinfection
Figure 21. Free and total chlorine residual as a function of time illustrating periods
of lower chlorine residuals at the distribution system entry points in the early
1990s (January 1992 through December 2004)
u>
o
a
c
o
U
HI
c
16-NOV-97
31-Mar-99
12-Aug-OO
25-Dec-01
9-May-03 20-Sep-04 2-Feb-06
Figure 22. Average free and total chlorine concentrations for water samples collected
from different sampling sites within the distribution system (1998 -2004)
54
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Figure 23 shows a plot of average free chlorine residual levels during LCR compliance
monitoring periods along with the 90th percentile lead data for the period January 1992 -
December 2004. The 90th percentile lead levels were low (less than the LCR AL) during
periods of high free chlorine residuals (July - Dec 1994 through July - Sept 1999) and
high (greater than the LCR AL) during periods of low free chlorine residuals
corresponding to disinfection with chloramines (July 2001 - June 2002 through July -
Dec 2004). Statistical analyses were not performed due to limited data. However, the
graph presents interesting information about a potential relationship between free
chlorine residuals and lead release that could be explored as follow-on work.
4 T-
I 3
IH
'E
-------
5.5.1 pH Variations
An evaluation of pH data collected at the entry points and within the DCWASA
distribution system indicated that pH variations were observed seasonally as well as
spatially from the entry points to sampling locations within the distribution system. pH
has a significant influence on lead corrosion and solubility, especially for the typically
observed Pb (II) species such as cerussite and hydrocerussite. Varying pH levels can
significantly affect the formation of protective scales on the interior of the pipes and the
capability of the system to maintain these scales in a stable form. In a recent study, Lytle
and Schock (2005a) found that changes in pH could destabilize passivating films on pipe
interiors, possibly resulting in increased lead solvency and release of scale particles.
Several corrosion control studies prepared for DCWASA or WA recommended that
distribution system pH should be maintained at a consistent level. For example, a study
by ECG, Inc. (1994) concluded that WA water treatment plants should optimize current
practices by rigorously maintaining a consistent pH level that would optimize the
Langelier Saturation Index in the positive range, as close to zero as possible. An expert
review of the ECG study (1994) by Jonathan Clement in 1996 recommended that
maintenance of a consistent distribution system pH, regardless of treatment selection,
should be addressed. Clement (1996) also recommended that pH variations of more
than 0.5 pH units should be avoided. A study by CH2MHNI (2004) evaluated two
corrosion control options, both of which required a constant pH: (1) maintaining a
constant, high pH at the two water treatment plants using either quicklime (current
practice) and/or sodium hydroxide; and (2) feeding a corrosion inhibitor such as
orthophosphate while maintaining a constant pH of about 7.7 throughout the year. A
summary of these corrosion control study reports is provided in Appendix A.
Daily average pH at the entry points to the distribution system (Dalecarlia and McMillan
Water Treatment Plants) and daily average pH in the distribution system are plotted as a
function of time in Figure 24.
56
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Q.
Dist. SyspH pH Dalecarlia A pH McMillan
Figure 24. Average daily pH at the distribution system entry points (Dalecarlia and
McMillan) and in the distribution system (1998 through 2004)
The differences in daily average pH for samples collected at the entry points compared
to samples collected in the distribution system are plotted as a function of time in Figure
25. A positive difference as shown in Figure 25 is an indication that the daily average pH
was lower in the distribution system compared to the entry point. A negative difference
indicates that the pH in the distribution system was higher than the pH at one of the
entry points. In some cases this observation was attributed to the difference in pH at
both entry points, and thus the pH in the distribution system could have been
intermediate between pH at Dalecarlia and McMillan entry points.
57
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Temporary switch
Reduced pH OCCT
i i
Conversion
to
-1.0
Dalecarlia Entry Point - Dist. Sys McMillan Entry Point - Dist. Sys
Figure 25. Difference between the average water pH at the distribution system entry points
and the average pH of water collected at different sampling sites throughout the
distribution system (1998 through 2004)
5.5.2 Spatial pH Variations
Data in Figure 24 and Figure 25 indicate that pH levels in the distribution system were
frequently 0.5 pH units less than, and in some instances as much as 1 pH unit less than,
the pH of finished water discharged from the water treatment plants. In Figure 25 the
difference in pH is calculated by subtracting the average pH value in the distribution
system from that at the respective distribution system entry points (Dalecarlia and
McMillan). These data indicate pH differences greater than the recommended allowable
pH difference based on studies by Clement (1996) and CH2MHILL (2004). As such,
these spatial pH variations could have caused adverse impacts on the stability of lead
scales and thus contributed to lead release.
5.5.3 Seasonal pH Variations
Figure 24 shows seasonal variation in pH, which was allowed to occur in the DCWASA
distribution system as part of the modified OCCT. During 1998 and 1999, the seasonal
trend in the average daily pH in the distribution system generally followed the seasonal
trend exhibited by the finished water discharged at the water treatment plants.
58
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5.5.4 Lower pH and Modified OCCT
Beginning with the reduced pH OCCT in 2000, the average daily pH in the distribution
system appeared to be noticeably lower than the finished water at the treatment plants
during 2000, 2001 and 2002. The cause of this change in pH between the point of entry
and distribution system is unknown. During 2000 and previously, pipe scales
presumably were acclimated to conditions of free chlorine and likely were dominated by
Pb (IV) species. After the switch to chloramines in November 2000, the average daily pH
in the distribution system generally remained low during 2001 and 2002. Under these
new conditions, the pipe scales likely were disrupted by the change in ORP and
chemical interactions likely were dominated by Pb (II) species. Further, low pH conditions
presumably were not favorable for the formation of stable lead scales. As a
consequence, low pH conditions, coupled with a reduction in ORP, likely contributed to
elevated lead levels after the switch in disinfectant to chloramines.
While Pb (IV) compounds are thought to have lower solubility than Pb (II) species,
solubility models also suggest that Pb (IV) solubility decreases with decreasing pH. As
discussed in a Section 5.2, in Pb (II) and Pb (IV) solubility models, Schock et al. (2001)
found that the PbO2 solubility minimum could occur at around pH 4. This phenomena is
opposite of the trend observed with Pb (II) where solubility was reduced with increasing
pH (Schock and Giani, 2004). Based on this understanding, the lower pH range in the
DCWASA system may have previously been adequate for maintaining Pb (IV) scales
under high free chlorine conditions, but too low of a pH for maintaining Pb (II) scales
under chloramine conditions.
5.5.5 Optimal Corrosion Control Treatment (OCCT)
The OCCT changes affecting pH control are discussed in detail in Section 2.4. This
section provides more in-depth analyses of the OCCT changes in an effort to quantify
their impact on lead release.
Distribution system pH varied from 7.0 to 8.9 over the years 1998 to 2004, and it
appears to vary seasonally, peaking in March or April every year except for the year
2002 (Figure 3, Figure 9, and Figure 24). In late 2001 and early 2002, distribution
system pH was significantly lower than in other years, with 3-month average pH values
less than 7.5.
System-wide pH data were analyzed to determine if statistical differences in pH occurred
before and after the observed increase in the 90th percentile lead levels for the
DCWASA system. Figure 26 shows a plot of the average, range, and standard deviation
of daily average pH data collected before and after the compliance period of July 2000
through June 2001. For each "box and whisker" diagram shown in the graph, the
horizontal line in the center of the box represents the average, the symmetrical box
represents the standard deviation, and the vertical bar represents the minimum and
maximum average of daily pH data collected during the designated compliance period (x
axis). The solid circles depict the 90th percentile lead levels (secondary y axis) for the
designated compliance periods. The disinfectant conversion, which occurred on
November 1, 2000, and the change in allowable minimum pH for OCCT, which occurred
in February, 2000, are shown by the vertical lines annotated in Figure 26. Results
indicate that the average pH before the disinfectant conversion ranged from 7.6 to 8.1
and it ranged from 7.4 to 7.9 after disinfectant conversion. Results also indicate that the
standard deviation and ranges of pH data appear to be similar, with the exception of the
59
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narrow range of values measured during the July through December 1999 compliance
period. While the pH range before and after the conversion is similar, the lowest pH
values occurred after the conversion during the July 2001 - June 2002 LCR monitoring
period. This period corresponds with the highest 90th percentile lead level as shown in
Figure 26.
T 80
- 70
re
Q
- 30
- 20
- 10
July - Dec Jan - June July-Dec Jan - June July 2000- July 2001- July-Dec Jan - June July - Dec Jan-June July - Dec
1998 1999 1999 2000 June 2001 June 2002 2002 2003 2003 2004 2004
Figure 26. Average daily pH and lead concentrations in first draw water samples before
and after the conversion from free chlorine to chloramines as the residual disinfectant
Lead data were evaluated as a function of pH before and after the pH changes in July
2000 as defined in the OCCT, and prior to orthophosphate addition. No correlation could
be found between total first draw lead concentrations and the average daily distribution
system pH values. The lack of a correlation between these two parameters was likely
due to: (1) the variability of both lead levels and pH levels measured, and using an
aggregate of pH and lead data collected at different locations throughout or connected to
the distribution system; and (2) variations between lead sources and lead levels in
individual LCR monitoring sites. The results did show that system-wide lead levels were
greater after OCCT pH changes (most of the data also corresponds to the post-
chloramines conversion period).
Table 13 summarizes the evaluation of data and information regarding distribution
system pH variations.
60
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Table 13. Summary evaluation of data and information -
distribution system pH variations
Data and Information Considered
Evaluation of Data and Information
Pertaining to this Possible Cause
Distribution system pH and alkalinity, 1998-2004
Distribution system entry points, pH and alkalinity,
1998-2004 (except for alkalinity data missing for
2000-2001)
HDR/EES analysis of WA pH data for entry points to
the distribution system 1992-2004 in conjunction with
other historical events (OCCT and disinfection
changes)
HDR/EES analysis of DCWASA lead data for LCR
compliance, 1998-2004
Correspondences pertaining to LCR compliance
(USEPA and DCWASA, 1997-2004)
Corrosion control studies (EGG, 1994; CH2MHill,
2004)
Expert review (Clement, 1996)
Schock and Giani (2004)
Data is plentiful, but confounding factors
make interpretation difficult. The cause of
lower distribution system pH levels
compared to entry point pH levels following
the disinfectant change is unclear.
pH variations and lower pH likely play an
important contributing role to scale
disturbance and lead release, along with a
disinfectant change.
5.6 Conversion from Elevated Free Chlorine to Chloramines for
Final Disinfection
On November 1, 2000, WA converted from free chlorine to chloramines for final
disinfection to reduce disinfection byproduct formation and to improve residual
disinfection in the distribution system. This change from free chlorine to chloramines has
been implicated as a potential causative factor in lead release, especially from lead
service lines. This section provides discussion on lead compliance monitoring data and
historical wastewater metals information collected before and after the conversion to
chloramines. In addition, this section provides discussion on special sampling data
collected during periods when WA switched to free chlorine for biofilm control (referred
to as a temporary disinfectant change) and lead profiling data collected during the
temporary disinfectant change. Further discussion is provided in this section with regard
to recent advances in theoretical understanding of oxidation reduction potential and its
impact on lead scales and the solubility of various forms of lead.
5.6.1 LCR Monitoring Results
To evaluate how lead levels changed before and after the conversion to chloramines,
lead compliance monitoring data were evaluated both on a compliance period basis and
on a monthly basis for the time period from July 1997 through October 2004. Figure 27
shows the LCR compliance data for this period, indicating when the minimum allowable
pH at distribution system sites was lowered from 7.7 to 7.0, and when the conversion
61
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from free chlorine to chloramines occurred. The minimum allowable pH in the distribution
system was lowered immediately prior to collection of compliance samples for the July
2000 to June 2001 compliance period. The conversion to chloramines occurred in
November 2000 in the middle of this compliance monitoring period. A total of 53 valid
compliance samples were collected during the July 2000 through June 2001 compliance
period, with 40 samples collected from July through October 2000 when DCWASA was
using free chlorine and 13 samples collected in June 2001 after the switch to
chloramines. Although there are several high lead levels measured prior to the
conversion (levels of 119 |o,g/L, 113 |o,g/L, and 128 |o,g/L), the percentage of samples with
lead levels >15 |o,g/L was greater after the conversion to chloramines (46%) than before
the conversion (8%).
Three elevated lead results occurred just prior the switch to chloramines. It is difficult to
determine, but unlikely that these few results have any significance with respect to pH.
A lead result occasionally reached this magnitude earlier under higher pH and high free
chlorine residuals. Similarly an occasional elevated result occurs under current
conditions with orthophosphate (Smith, 2007). It is possible that lead release and low
lead levels had been maintained by the high oxidation-reduction potential of the water
and not controlled by pH.
Figure 28 displays the average and 90th percentile lead levels by compliance period.
The average and 90th percentile lead levels were higher after chloramination began,
when compared to the seven previous compliance periods. Figure 29 again shows the
LCR compliance data for the period from 1997 through 2004, with the overall average
lead level before conversion to chloramines (when free chlorine was used from July
1997 through October 2000) of 5 ug/L, approximately one-fourth the average lead level
measured after conversion to chloramines (November 2000 through July 2004), which
was 22 ug/L. This difference is significant, with a p-level of 0.0000 (t-test statistics as
reported using StatSoftฎ STATISTICA software, Release 5.1). The p-level represents
the probability of error involved in accepting the hypothesis that there is a difference in
the two means.
62
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300
JulyOO-OCCT
minimum pH
requirement in dist.
system lowered from
7.7 to 7.0
Mar-97 Dec-97 Oct-98 Aug-99 Jun-00 Apr-01 Feb-02 Nov-02 Sep-03 Jul-04
July-Dec 1997
July 2000-June 2001
OJan -June 2004
D July-Dec 1998
O July 2001 -June 2002
A July-Dec 2004
A Jan -June 1999
+ Jan -June 2003
O July-Sept 1999
D July-Dec 2003
Figure 27. Lead concentrations in first draw water samples collected during different time
intervals (July 1997 through December 2004)
OCCT Minimum pH
Requirement in
Dist. Sys. lowered
from 7.7 to 7.0
Compliance Period
Figure 28. Average and 90th percent! le lead concentrations in first draw water
samples during different compliance periods (January 1992 through December
2004)
-------
70
60
-T 50
u
I
co
40
:r 30
20
10
Free Chlorine
/
OCCT Minimum pH '
Requirement in
Dist. Sys. lowered
from 7.7 to 7.0
Average before
4 chloramines = 5 jig/L
07-1 997 to 07/2000
. / % ^
^-^ V___
Chloramines
Orthophosphate
Added
h^,
*
^ ซL
Average after ^
chloramines = 22 ng/L
11/2000 to 07/2004 4
A.
o
, A
O
^/
<
\~+
*
o
4
A
* ,#
be<5 ^
0ฐ
Figure 29. Average lead concentrations in first draw water samples collected during
different months (July 1997 through October 2004)
5.6.2 Historical Data on Wastewater Metals
DCWASA examined historical data on lead, copper, and zinc loading to the Blue Plains
Wastewater Treatment Facility before and after the November 1, 2000 conversion to
chloramines to determine if the change increased metals loading. DCWASA found no
significant increase in lead, copper, or zinc levels after November 2000 (Rizzo, 2004).
5.6.3 Lead Levels during Temporary Disinfectant Change
Chloraminated systems may periodically switch to free chlorine for the purpose of
controlling microbial regrowth in the distribution system. This section discusses the
temporary switch to an alternate disinfectant (free chlorine) for both 2003 and 2004.
USEPA Region 3 compared LCR lead results during 2003 during a temporary switch to
free chlorine to periods when chloramine was used for disinfection. Table 14 presents
the LCR sampling results for the first half of 2003 when free chlorine was used from
March 10 to April 10, 2003. Sampling results show that after chloramine addition was
resumed in April, the number of samples with elevated lead levels increased. Another
potential contributing factor to the higher number of samples with elevated lead levels in
late spring may have been higher water temperature; however, it is difficult to evaluate
the relative impact of water temperature versus the change in disinfectant practices on
changes in lead levels measured at the tap.
64
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Table 14. LCR lead results for January through June 2003
LCR Sampling Results
Number of samples
Range of First Draw Lead (ug/L)
Average First Draw Lead (pg/L)
Number of Samples >1 5 pg/L
% of Samples > 1 5 pg/L
Before March 10,
2003 (chloramines)*
22
ND to 62
7
3
14
March 10-April
10,2003
(free chlorine)**
29
ND to 21
5
2
7
From April 11
(chloramines)***
53
NDto 118
13
12
23
ND = Not Detected.
*LCR samples January 1 through January 31, 2003
**LCR samples March 13 through March 28, 2003
***LCR samples April 17 through June 30, 2003
Source: USEPA Region 3
USEPA Region 3 also presented lead results in samples collected at 12 specific
sampling sites during the March through April 2003 free chlorine period and samples
collected at these same sites during the July 1, 2001 to June 30, 2002 monitoring period
when chloramine was being used. Of these 12 sites, 8 had lead levels greater than 15
ug/L during the 2001 through 2002 monitoring period (chloramine period), whereas only
5 sites had elevated lead levels during the March 2003 monitoring period (free chlorine
period). While not a rigorous statistical evaluation, these results suggest that elevated
lead levels occurred during use of chloramines.
HDR/EES summarized LCR lead results for the period in 2004 when free chlorine or
chloramines were used. These results are presented in Table 15. These data indicate
that higher lead levels were apparently measured during chloramination compared with
lead levels measured during the period of free chlorine use. It is worth noting that some
of the data in Table 15, after the temporary disinfectant change to free chlorine, includes
the period after June 1, 2004 when orthophosphate had been introduced into the 4th
High Pressure Zone, which was almost 3 months earlier than orthophosphate addition to
the entire DCWASA system (Appendix A - Timeline). Based on available location data
from LCR monitoring and maps of the 4th High Pressure Zone, some sampling sites
included in the analysis shown in Table 15 may be in the 4th High Pressure Zone. This
scenario could cause additional variability because some results may be affected by
orthophosphate. Further spatial analyses may be beneficial to more clearly define
conditions under which samples were taken, and potential impact on lead results.
65
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Table 15. LCR lead results for March through June 2004
Number of samples
Range of First Draw Lead (pg/L)
Average First Draw Lead (pg/L)
# Samples >15 |jg /L
% of Samples >15 |jg /L
Before April 2,
2004
(chloramines)*
28
2-190
28
19
68%
April 2, 2004 to May
7, 2004
(temporary
disinfectant change
to free chlorine)**
12
3-38
17
4
33%
From May 8, 2004
(chloramines)**
30
1 -97
37
23
77%
*LCR samples MarcM, 2004 through April 1, 2004
**LCR samples April 7, 2004 through April 29, 2004
***LCR samples June 2, 2004-June 17, 2004.
5.6.4 Lead Profiling during Temporary Disinfectant Change
Limited LCR data for lead were available during the temporary disinfectant change.
Consequently, HDR/EES also reviewed an additional source of data - lead profiles -
taken during chloramine disinfection and during a temporary change to free chlorine
disinfection.
Lead profile data collected during periods of chloramination was compared to periods of
free chlorine use during the 2004 temporary switch to free chlorine. Fourteen profiles
were completed during the period when chloramines were used (December 2003
through March 2004); 12 profiles were completed during the temporary switch to free
chlorine that occurred from April 1, 2004 through May 7, 2004; 2 sites were completed
after the temporary switch to free chlorine when chloramines were re-introduced to the
system (May 8, 2004 through July 16, 2004); and 17 profiles were completed after
orthophosphate addition (December 2004 through January 2006). Appendix A contains
graphical summaries of these 45 lead profiles grouped by the period in which they were
collected (i.e., during chloramination, during the temporary switch to free chlorine, after
the temporary switch to free chlorine when chloramination was resumed, and during
post-orthophosphate addition). Review of these data indicates that higher lead levels
were experienced during the period when chloramination was implemented when
compared with periods when free chlorine was used temporarily.
Lead profile data were collected at five specific sites during periods of chloramination
and periods of the temporary switch to free chlorine, providing data with which to
compare the impact of disinfection change on lead levels at specific sites. These data
are displayed in Figure 30 through Figure 34. Each profile is annotated to indicate which
samples were representative of standing water in the premise plumbing, the lead service
line, or the water main. This information regarding the segment of the piping system
was based on notes included with the sampling results. Results from four of the five sites
indicate that lead levels were lower during periods of free chlorine compared with lead
levels measured when chloramines were used for disinfection. At House #1 (Figure 30),
total lead levels representative of the lead service line reached 80 ug/L when
chloramines were used, but were less than 10 ug/L during the temporary switch to free
chlorine. House #2 (Figure 31) shows profiles after a partial lead service line
replacement, during both chloramination and during the temporary switch to free
chlorine. There appears to be a small increase in lead levels in the LSL segment during
66
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the temporary switch to free chlorine, possibly due to scale disturbance. However, the
lead levels measured during both periods were relatively low, making it difficult to
distinguish differences that may have been due to the disinfectant conversion. In
addition, the date for the background sample (sample "0") and the first liter sample
indicate anomalous results with dissolved lead higher than total lead. The reason for this
anomaly is unknown but could also be attributed to analytical inconsistencies at these
low lead levels.
At House #3 (Figure 32), total lead levels reach 24 ug/L in the LSL segment during
chloramination. During the temporary switch to free chlorine, the first 1-liter sample
exhibited high total lead (110 ug/L) primarily due to particulate lead. The remaining
samples were less than 10 ug/L during the temporary switch to free chlorine. The high
particulate lead for House #3 at sample 'X' could be attributed to scale disturbance and
detachment of particulate lead, since 'X' represents water hammer conditions, as
discussed previously. At House #4 (Figure 33), the highest total lead levels measured
were 110 ug/L during chloramination and only reached 9.7 ug/L during the temporary
switch to free chlorine. Total lead levels at House #5 (Figure 34) reached 82 ug/L during
chloramination and 45.6 ug/L during the temporary switch to free chlorine. These
results, as summarized in Table 16, therefore indicate lower lead levels during the
temporary switch to free chlorine than during chloramination. Additional details
regarding special conditions (such as partial LSL replacements) under which the profiles
were conducted are listed in Appendix A. Table 17 summarizes the evaluation of data
and information regarding conversion from free chlorine to chloramines for final
disinfection.
67
-------
13 17 21 25 45 X
-ion _,
-i/in
120 -
-inn
on
en
/in
20 -
n -
In-house
Plumbing
^^m 1 ^m 1 ^^i 1
Total L
Lead Service
Line
i i 1 ! 1
ead D Dissolved Lead
Main L-
13 17 21 25 25+3 25+10 0 X
Liter
I Total Lead D Dissolved Lead
Figure 30. Lead profiles for House #1 when a) chloramines were being used as the
disinfectant (sample collected January 13, 2004) and b) during a temporary switch to free
chlorine as the disinfectant (sample collected April 29, 2004).
68
-------
180
160
120
ง. 100
80
60
20
In -house Lead
Plumbing Service
Line
Majn
T8
180
iA.n -
-inn
on
en _
n -
Total Lead D Dissolved Lead
In-house Lead Main
Plumbing Service Q
^^
Line
1 2 4 5 6 8 10 12 14 16 16+3 16+5 16+7 16+9 16+11 X 0
Liter
Total Lead D Dissolved Lead
Figure 31. Lead profiles for House #2 when a) chloramines were being used as the
disinfectant (sample collected February 24, 2004) and b) during a temporary switch to free
chlorine as the disinfectant (sample collected April 26, 2004).
69
-------
ifin
-Mn
120 -
"Q*
Q. 100 -
ฃ
D
(0 on
en
/in
nn
n _
In-house
Plumbing
njhfc
Lead Service
Line
fcfcfc
Mam
a
_
1 2 3 5 7 9 10 11 13 15 18 21 24 27 0 27+327+10 X
Liter
-ion
-i /in
-ion
"o*
ซ mn
^
o
S 80-
fin
An
on
n -
In-house
Plumbing
Total Lead D Dissolved Lead
Lead
Serivce Line
-. -,
Main .
1 2 3 5 7 9 10 11 13 15 18 21 24 27 27+327+10 0 X
Liter
I Total Lead D Dissolved Lead
Figure 32. Lead profiles for House #3 when a) chloramines were being used as the
disinfectant (sample collected March 30, 2004) and b) during a temporary switch to free
chlorine as the disinfectant (sample collected April 30, 2004).
70
-------
140 -
120 -
_Q
ซ -inn
^
c
_l
40 -
20
n -
In-house
Plumbin
I,
i
3
i
!
i
i
i
i
Se
L
rv
ea
ce
. . Main _
Line 3
fc
1 1 1 1 1 1 II I 1
Information was not available for
Dissolved Lead at Liter 9
11 13 15 18 21 24 27 27+327+10 X
Liter
a
ra
01
180-r
60
40
on
n _
In-house
Plumbing
Total Leat
Lead
Serivce Line
nlnnin^
J D Dissolved Lead
Main .
D
1 2 3 4 5 7 9 11 13 15 18 21 24 27 00 27+327+10 X
Liter
I Total Lead D Dissolved Lead
Figure 33. Lead profiles for House #4 when a) chloramines were being used as the
disinfectant (sample collected March 31, 2004) and b) during a temporary switch to free
chlorine as the disinfectant (sample collected May 7, 2004).
71
-------
180
160
1 2 4 5 6 7 8 9 11 13 16 19 19+3 0 X
180
160 -
140 -
120 -
0. 100
60
I Total Lead D Dissolved Lead
In-house
Plumbing
Lead
Serivce Line
Main
1 2 4 5 6 7 8 9 11 13 16 19 19+3 19+10 0 X
Liter
I Total Lead D Dissolved Lead
Figure 34. Lead profiles for House #5 when a) chloramines were being used as the
disinfectant (sample collected February 9, 2004) and b) during a temporary switch to free
chlorine as the disinfectant (sample collected May 18, 2004).
72
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Table 16. Maximum lead levels measured from profiles during
chloramination and periods of temporary disinfectant change to free chlorine
House
1
2
3
4
5
Maximum Lead Level Measured During Profile
Chloramination
81
7
24
110
82
Temporary disinfectant
change to free chlorine
5.4
7
5.7*
9.7
45.6
*First draw contained high particulate lead; next highest sample was 5.7 jug/L lead.
Table 17. Summary evaluation of data and information - conversion from free
chlorine to chloramines for final disinfection
Data and Information Considered
Evaluation of Data and Information
Pertaining to this Possible Cause
DCWASA lead monitoring data, 1994-
2004.
USEPA Region 3 analysis of LCR lead
results for free chlorine periods vs.
chloramines periods, 2002-2003.
HDR/EES analysis of LCR lead results for
free chlorine periods vs. chloramines
periods, 2004.
HDR/EES analysis of DCWASA Lead
Profiles in Excel spreadsheet obtained
from USEPA Region 3.
Higher lead levels were measured and the number of
samples with elevated lead levels increased when
chloramines were used, when compared to periods
when free chlorine was used as a disinfectant.
HDR/EES analysis of DCWASA 4th High
Pressure Zone hydrant WQP monitoring
data (specifically ORP) in the timeframe
leading up to, during and after the 2004
free temporary disinfectant change
Higher lead levels in LCR monitoring and lead profiles
correspond to the periods of lower ORP typically
observed during disinfection with chloramines. Lead
levels in LCR monitoring and lead profiles appear to
be lower during a period of higher ORP corresponding
to the 2004 free temporary disinfectant change.
Laboratory and field studies as reported by
Schock, Lytle, and Giani (see references)
on mechanism and presence of Pb (IV)
versus Pb (II) compounds on the interior of
lead service pipes.
Occurrence of Pb (IV) compounds on DCWASA lead
service line specimens supports the theory of
formation of Pb (IV) compounds under higher ORP
conditions.
USEPA Region 3 report on loadings to
Wastewater Treatment Plant (WWTP)
2004 (report by G. Rizzo, USEPA Region
3, Spring 2004).
No significant difference in lead, copper, and zinc
loading to the Blue Plains Wastewater Treatment
Facility after the conversion to chloramines.
73
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5.7 Distribution System Water Quality Characteristics
Water quality characteristics such as alkalinity, specific conductance, temperature, and
organic levels and speciation can impact pipe scale formation and lead release in water
distribution systems. Furthermore, the occurrence of biological events like nitrification
also can potentially affect lead release in lead service line and premise piping. This
section provides an evaluation of available water quality data regarding these
characteristics in relation to lead levels in DCWASA tap water samples.
5.7.1 Alkalinity
System-wide alkalinity data were analyzed to determine if any statistical differences
occurred before and after the pH adjustment for OCCT or following the disinfectant
conversion. As shown in Figure 35, the average alkalinity in tap water samples ranged
from 64 to 112 mg/L as CaCO3 before the pH adjustment for OCCT and the disinfectant
conversion. The average alkalinity ranged from 57 to 89 mg/L as CaCO3 after the OCCT
pH adjustment and disinfectant conversion. The range and standard deviation values
also appear to be similar, except for the period when conversion occurred (2000-2001)
and in the following compliance period (2001-2002). Both of these periods cover an
entire year rather than 6 months, which could explain the higher variability in these
results. These results generally indicate that the variation in alkalinity did not appear to
be a primary contributor to the observed increase in lead following the conversion to
chloramination. This is based on the fact that elevated lead levels persisted during both
higher and lower alkalinity concentrations. A linear regression analysis between total
lead concentrations and alkalinity in the distribution system before and after the OCCT
pH change (not shown here) further indicated that there was no correlation between the
two parameters.
5.7.2 Temperature and Specific Conductance
Temperature and specific conductance were also evaluated with regards to their
variability before, during, and after the July 2000 - June 2001 LCR monitoring period
(data not shown). For both parameters, there was no observed difference in their
variability, and no correlation with lead levels, over these time periods. Nevertheless,
previous findings indicate that either of these parameters, acting in concert with other
parameters or by themselves, may influence corrosion rates.
Water temperature can affect lead corrosion rates (Schock et al., 1996); however, the
impact of fluctuations in water temperature on corrosion rates is not straightforward.
This is because temperature affects many other processes and parameters such as
buffering capacity, lead solubility, dissolved inorganic carbon solubility, and processes
like dissolution, diffusion, and precipitation. Schock et al., (1996) indicated that the
response of passivated pipes to temperature variation will depend on the solubility
trends of the non-lead solids which comprise the scale.
Specific conductance or conductivity is a function of the concentration and composition
of dissolved solids in a water sample. Ions of particular interest in drinking water systems
include sodium, calcium, magnesium, chloride, carbonate, and sulfate (AWWA, 2005).
Increased conductivity values are indicative of higher concentrations of these and other
ions. Greater conductivity means that the water is better able to complete the
electrochemical circuit and conduct a corrosive current (AWWA, 2005). If sulfate and
74
-------
chloride are present at sufficient concentrations the water is likely to exhibit increased
corrosiveness towards iron-based materials, depending on the mass ratio of chloride to
sulfate. If the conductivity is composed primarily of bicarbonate and hardness ions, the
water may be highly corrosive towards copper (Schock, 1999). Waters with low
conductivity may also be corrosive to lead and increase lead solubility, since these
waters tend to dissolve (corrode) materials with which they are in contact in an attempt
to reach equilibrium (AWWA, 2005).
160
140
120
O
o
S LJ
100
90th Percentile First
Draw Lead
^Conversion to
Chloramines
July - Dec Jan - June July - Dec July 2000 - July 2001- Jan - June July-Dec Jan - June July - Dec
1998 1999 1999 June 2001 June 2002 2003 2003 2004 2004
Figure 35. Average daily alkalinity and lead concentration in first draw water samples
before and after the conversion from free chlorine to chloramines as the residual
disinfectant
5.7.3 Natural Organic Matter
Previous research has suggested that natural organic matter (NOM) can influence
corrosion processes (Colling et al., 1987, Marani et al., 1995, Schock et al., 1996;
Hopwood et al., 2002; Korshin et al., 2005). The impact of NOM on corrosion processes
depends on its concentration and physicochemical characteristics (Korshin et al., 2005).
The characteristics of NOM may become altered by drinking water treatment processes,
subsequently changing its impact on corrosion rates in distribution systems (Korshin et
al., 2005). Korshin et al., (2005) found that NOM increased the soluble levels of lead
and tin significantly. Here, the presence of NOM in suspension caused larger colloidal
lead and solder particles to break down into smaller formations or contribute to soluble
metal. Additionally, amorphous films were observed to form on corroding lead surfaces
in the presence of NOM, though it was not noted whether this film acted as a passivating
layer. Nevertheless, it was concluded that the concentration and characteristics of NOM
present, in addition to pH and alkalinity, may be one of the important factors in
75
-------
establishing the predominance of and transitions between alternative lead solids during
corrosion.
5.7.4 Nitrification
The occurrence of nitrification events in the DCWASA distribution system was
investigated for potential impacts on water quality. While nitrification does not directly
influence corrosion, it could potentially affect distribution system pH and alkalinity. The
Washington Aqueduct has been sampling for nitrification indicator parameters (e.g.,
nitrite, nitrate, ammonia, pH, and bacteria), but no evidence suggesting that widespread
nitrification was occurring in the distribution system was found (Rizzo, 2004).
Furthermore, the occurrence of nitrification in the distribution system has not been
documented by either DCWASA or USEPA Region 3 (Rizzo, 2005b). Although a more
rigorous analysis of water quality data may reveal more information on the occurrence
and subsequent impacts of nitrification in the DCWASA distribution system, based on
the findings to date, it does not appear to be a significant factor.
5.8 Galvanic Corrosion of Lead Service Lines
One issue of concern associated with partial replacement of lead service lines with
copper piping is the potential for galvanic corrosion. Galvanic couplings can create loss
of metal at the anode and subsequent release into the water column. Theoretically, this
mechanism could have a significant impact on lead corrosion rates when copper and
lead are coupled. However, there is some uncertainty regarding the duration of
accelerated corrosion rates caused by the coupling and whether an accelerated
corrosion rate would be observed when the surface of the lead piping has been
passivated. Partial LSLR was conducted during a timeframe when DCWASA continued
to fail to meet the LCR 90th percentile AL. Therefore, the potential impact of this
process on lead levels in service lines was evaluated further.
Reiber and Dufresne (2005) conducted a laboratory study to characterize the electrical
impacts associated with galvanically-coupled lead and copper service lines to determine
if replacing a portion of a lead pipe with copper piping might cause accelerated lead
release in drinking water. This study was conducted using lead service lines which had
been recently removed from DCWASA residences and water which had a baseline
chemistry comparable to DCWASA's, including similar pH, alkalinity, hardness, and
conductivity. The study was conducted under controlled laboratory conditions designed
to accelerate lead release.
Reiber and Dufresne (2005) used two experimental set-ups for this evaluation: indirectly
coupled cells and directly coupled pipe segments. Polarization cells connected in a
hydraulic series with electrical connections between individual cells were used for
evaluating indirectly connected lead and copper pipe segments. This approach allowed
the researchers to manipulate cathode and anode ratios, the current flow between cells,
and evaluate metal release. In the second experimental approach, %-inch diameter
copper tubing was directly connected to each lead service line section. To ensure
electrical coupling, the lead service line was grooved to match the end of the copper
segment. In both experimental approaches, electrodes were used to measure changes
in the pipe surface potential. The electrodes could measure potential shifts of a millivolt
or less, while the theoretical impact of galvanic corrosion was expected to be on the
order of hundreds of millivolts.
76
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For the indirectly coupled experimental approach, the researchers found that the
galvanic impact could be measured immediately for passivated lead service lines;
however, the change in the pipe surface potential was on the order of only a few
millivolts. A much greater shift in surface potential was measured when unpassivated
lead service lines were indirectly coupled to copper piping.
When the pipes were directly connected, there was no significant impact on the pipe
surface corrosion potential for the passivated lead service lines. However, the
unpassivated lead piping did experience an electrochemical impact when directly
coupled to the copper piping. Figure 36 presents a profile illustrating the surface
potential along the length of directly coupled lead (passivated and unpassivated
conditions) and copper service lines. Sample locations are represented by the electrode
sites. The surface potential of the passivated lead service line deviates only slightly from
the freely corroding lead surface potential, and only for the section of pipe that is within
approximately 4 centimeters of the direct coupling.
u
un
200T
100"
0'
-ง -100
5 -200
o
CL
2 -300
-------
during continued failure to meet the LCR 90th percentile AL. A summary of the galvanic
corrosion data from Reiber and Dufresne (2005) is given in Table 18.
Table 18. Summary evaluation of data and information -
galvanic corrosion of lead service lines
Data and Information
Considered
Reiber and Dufresne (2005)
Evaluation of Data and Information Pertaining to this
Possible Cause
Laboratory testing results indicate that galvanic coupling of lead
and copper service lines (e.g., partial lead pipe replacements)
likely contributed minimally to lead release in drinking water in
connections to the DCWASA distribution system.
5.9 Effect of Grounding Currents on Lead-Bearing Components
The impact of grounding currents on metal release from piping systems has been
studied with the primary focus on copper tubing (Reiber and Dufresne, 2005). With
respect to lead service lines, studies have produced conflicting results (Bell, 1998 and
AwwaRF, 1996) regarding whether grounding currents present at the external pipe
surface impact metal release from the internal pipe surface to drinking water.
Reiber and Dufresne (2005) conducted a laboratory study to investigate whether
grounding currents could have a significant and prolonged impact on metals release
from lead service lines and leaded-brass appurtenances. This study utilized a flow-
through recirculation loop consisting of DCWASA lead service line segments, new
copper tubing, water reservoir, and flow control and pumping hardware. High
impedance reference electrodes were sited along the lead service line segments to
monitor surface potential on the interior of the pipe while different current forms,
amperages, voltages and grounding scenarios were applied to the test rig. Testing did
not intend to replicate distribution system conditions, but instead to evaluate various
scenarios by generating the highest possible metal release and the greatest lead service
line surface effects.
Results showed that impressed currents (AC or DC) on lead service lines and copper
service lines, including grounding type currents, had no impact on the internal corrosion
of the household service lines or any other plumbing appurtenances that were tested.
Figure 37 presents profiles of the surface potential response to AC and DC currents.
The investigators concluded that there is likely no acceleration of corrosion associated
with the conventional practice of electrical system grounding to household water
systems. Reiber and Dufresne (2005) indicate that this may be the case because
imposing an external current on the pipeline changes the potential of all surfaces, both
external and internal, and everything in contact with the piping. The internal surface
potential relative to the water contained in the pipe may not change since the potential of
the water has been shifted to an amount equal to the shift of the potential of the interior
pipe surface. Corrosion would occur when the internal surface potential changes
relative to the water in the pipe. Table 19 shows the summary evaluation of data and
information related to grounding currents.
78
-------
0 100 200 300 400 500 600 700 800 900 1000 1100 1200
Time Domain (sec.)
TJ
I
I
20,
I
u 0
-100
^ -200f
o
Q-
3
l/l
.D
a.
-300
-400
-500
AC Current Off
0 100 200 300 400
500 600 700 800
Time Domain (sec.)
900 1000 1100 1200
Figure 37. Impressed current impacts for separate DC (upper) and AC (lower) tests on
surface potential of a lead service line coupled to copper tubing
Table 19. Summary evaluation of data and information - grounding currents that
affect corrosion of lead-bearing components
Data and Information
Considered
Reiber and Dufresne (2005)
Evaluation of Data and Information Pertaining to this
Possible Cause
Laboratory testing results indicate that grounding currents
on lead service lines and copper service lines had no
discernable impacts on the internal corrosion of the
household service lines or any other plumbing
appurtenance that were tested.
79
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5.10 City-Wide Meter Replacement Program
From March 2002 through May 2005, more than 116,000 meters were replaced in the
DCWASA system by contractors (data from Raymond Hanesworth, DCWASA). This
meter replacement program could be a potential cause of lead release into the drinking
water in two ways: (1) soluble lead release from the meters themselves; and/or (2)
disturbance of connective piping that could release and expose lead-bearing scales.
Keefer and Giani (2005) conducted a laboratory study from April to June 2004 to
evaluate lead release from two new bronze water meters and subsequent uptake by
water. Three different water treatment strategies were tested: free chlorine disinfection,
chloramine disinfection, and chloramine disinfection with orthophosphate addition. The
tap water used in the study contained lead levels that were less than 2 ug/L. Lead levels
were measured after water was held in the meters for various stagnation periods ranging
from 15 minutes to 23 hours. All three water treatment strategies resulted in some lead
release by the meter and uptake by the water as summarized in Table 20.
Table 20. Lead release from bronze water meters in laboratory study
Water Treatment Strategy
Free chlorine disinfection
Chloramine disinfection
Chloramine + orthophosphate
Lead Levels after
Stagnation Period
(ug/L)
14-165
20-145
2-22
Stagnation Periods
Used (hrs)
0.25-21
0.5-23
0.5-18
Source: Keefer and Giani (2005)
The results of this study suggest that bronze meters may contribute to elevated lead
levels in drinking water (Keefer and Giani, 2005). However, lead profiles were used by
Keefer and Giani (2005) to illustrate why lead release from bronze meters may in fact
not substantially increase lead levels in samples collected at residential taps. This
conclusion was based on the following: dilution effects from the meter to the tap; dilution
effects during sample collection; and the age of the bronze meter. There is little other
data available on the potential release of lead and the contribution to lead levels at the
tap associated with meter replacement. Based on currently available data and
information, the contribution of lead by the city-wide meter replacement programs is
small and likely not a major contributor to lead levels at the tap. Table 21 is a summary
evaluation of data and information related to the city-wide meter replacement program.
Table 21. Summary evaluation of data and information - city-wide meter
replacement program
Data and Information
Considered
Evaluation of Data and Information Pertaining to this
Possible Cause
Keefer and Giani (2005)
Laboratory testing results indicate that bronze meters could
contribute lead levels to drinking water. However, the
contribution of lead is likely not substantial due to dilution
effects (in plumbing and in the sampling container) and the
age of the bronze meter.
80
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5.11 Drought Conditions and Effects on Corrosivity of DCWASA
Water
Two periods of drought conditions have occurred in recent years in the Washington,
D.C. area. From the fall of 1998 through the early summer of 1999, lower than normal
rainfall contributed to drought conditions in the Potomac River basin (Steiner and Hagen,
2000). From the fall of 2001 through the summer of 2002, below normal rainfall and
record low groundwater levels and stream flows were observed (Kiang and Hagen,
2004).
Available source water quality data were reviewed for the period of January 1998
through September 2004 to compare water quality conditions during the aforementioned
drought periods (fall 1998 to summer 1999 and fall 2001 to summer 2002) and the
interim period (fall 2000 to summer 2001). A limited review of source water-specific
conductance and alkalinity data, collected on a monthly basis and summarized in Table
22, shows no obvious differences between the drought periods and the period with
assumed normal precipitation.
Table 22. Source water quality data (1998 through 2000)
Period
Jan 1998-Aug 1998
Sep 1998-Aug 1999
(Drought)
Sep 1999-Aug 2001
Sep 2001 -Aug2002
(Drought)
Sep 2002 -Dec 2004
Specific
Conductance
(^S/cm)a
Average
ND
315
300
340
339
Range
ND
233-371
195-405
204-454
273-392
Alkalinity
(mg/L as CaCO3)b
Average
97
109
81
73
62
Range
83-106
69-132
64-108
30-117
40-95
Temperature
(ฐF)b
Average
61
60
60
63
53
Range
38-85
31-88
33-85
35-87
33-78
ND - No data available.
a Untreated source water data.
b Entry point data collected at McMillan Water Treatment Plant. Similar alkalinity and water
temperature values were observed for the Dalecarlia plant.
Figure 38 shows the average daily conductivity of water at the distribution system entry
points during the two drought periods reported from January 1998 through December
2004. It was assumed that a drought could cause an increase in conductivity during low
rainfall periods as a result of reduced dilution effects. The data shown in Figure 38 do
not show a clear indication that the conductivity of water entering the distribution system
increased or decreased substantially during the drought periods relative to non-drought
periods.
81
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HI
u
c
ro
1
o
c
o
o
500
450 -
400 -
350 -
300 -
250 -
200 -
150
Drought Periods
\
Jan 1998-Aug 1998 Sept 1998 - Aug 1999 Sept 1999 - Aug 2001 Sept 2001 - Aug 2002 Sept 2002 - June 2004
Figure 38. Average daily specific conductance of water at the distribution system entry
points during drought periods
The average daily alkalinity for water at the distribution system entry points is shown in
Figure 39. During the first drought period, alkalinity increased relative to that measured
in the preceding period; however, alkalinity was lower during the second drought period.
In fact, the average alkalinity values showed a decreasing trend following the drought
which occurred during 1998-1999. Thus, these data do not indicate a clear relationship
between finished water alkalinity and drought conditions.
The average daily finished water temperature at the distribution system entry points is
shown in Figure 40. From the data shown here the average finished water temperature
did not differ substantially during the two drought periods relative to the non-drought
ones. Indeed, periods of drought do not have to necessarily correspond to periods of
elevated air temperatures. Instead drought is a measure of precipitation. Similar to other
parameters, these data do not show a clear indication of a meaningful change in
temperature which could impact the corrosion potential of water entering the distribution
system.
82
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160
140 --
120 --
O
re
O
ซ 100
"&
> 80 --
60 -
40 --
20
Jan 1998-Aug 1998 Sept 1998 - Aug 1999 Sept 1999 - Aug 2001 Sept 2001 - Aug 2002 Sept 2002 - June 2004
Figure 39. Average daily alkalinity of water at the distribution system entry points during
drought periods
100
90 -
80 -
70 -
60 -
50 -
40 -
30
Drought Periods
Jan 1998-Aug 1998 Sept 1998 - Aug 1999 Sept 1999 - Aug 2001 Sept 2001 - Aug 2002 Sept 2002 - June 2004
Figure 40. Average daily temperature of water at the distribution system entry points
during drought periods
-------
Drought conditions may also quantitatively and qualitatively affect the concentrations
and characteristics of NOM entering raw water systems (Volk et al., 2002; Maurice et al.,
2001). These changes result from changes in the amount and origin of the water that
enters a surface water system. For instance, during drought periods there is less surface
water runoff, and in turn a greater portion of the river's base flow is groundwater
seepage. The organic loading rate to a river may be lower during drought periods and
may thus exert a lower chlorine demand compared to non-drought periods. The limited
amount of water quality data (entry point and average distribution system free chlorine
concentrations) that was available for the DCWASA system did not indicate that this was
the case during the two drought periods and did not show any difference relative to the
non-drought periods. This cannot be directly linked to the amount of NOM entering the
DCWASA distribution system, as no data was available on the concentration or
character of these organics. However, it is likely that any changes in NOM
concentrations that occurred during the drought periods were not significant enough to
dramatically alter the chlorine demand or in turn the ORP of the finished water.
Based on available source water quality data and the data evaluation discussed above,
results do not implicate drought as a major factor in causing lead release. This
conclusion is based on the observations that the noted water quality parameters, which
may affect corrosion rates, did not change appreciably during the two drought periods
relative to non-drought ones. These observations are summarized in Table 23.
Table 23. Summary evaluation of data and information - drought conditions and
their effect on corrosivity of DCWASA water
Data and Information Considered
Evaluation of Data and Information
Pertaining to this Possible Cause
Steiner and Hagen (2000)
Kiang and Hagen (2004)
HDR/EES analysis of DCWASA lead data for
LCR compliance, 1998 - 2004.
HDR/EES analysis of available data for
specific conductance, alkalinity, and
temperature, 1998-2004.
Data yields no definitive trend.
Drought conditions likely were not a major
contributor to elevated lead levels.
84
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6. CURRENT STATUS OF DCWASA SYSTEM AND
POSSIBLE FOLLOW-ON WORK
This section provides a brief summary of the current LCR compliance status of the
DCWASA system. In addition, this section identifies possible follow-on work based on
available findings and conclusions drawn from this study.
6.1 Current LCR Compliance Status of DCWASA System
DCWASA, in conjunction with the USEPA and WA, has been conducting a series of
studies aimed at: (1) determining the possible cause(s) of high lead levels since LCR
compliance monitoring in July 2000 - June 2001; and (2) identifying solutions to reduce
and control lead levels at consumers' taps. As part of these studies, DCWASA
conducted a partial system application of orthophosphate in a portion of the distribution
system known as the 4th High Pressure Zone beginning June 1, 2004. Based on results
of this demonstration test, orthophosphate was subsequently added as treatment at the
WA water treatment facilities to cover the entire DCWASA system beginning August 23,
2004 for the purpose of lowering lead levels at the tap.
The OCCT designation was modified and clarified on August 3, 2004 and September 8,
2004 to consist of application of orthophosphate subject to stated conditions and water
quality parameters (source: correspondence from USEPA Region 3 to WA and
DCWASA dated August 3, 2004). USEPA Region 3 stipulated that WA meet a pH
range of 7.7ฑ0.3 for finished water leaving both water treatment plants during the
distribution system passivation period. A goal of 7.7ฑ0.1 was set, although this pH
range was not enforceable. For distribution system samples, the same enforceable pH
range (7.7ฑ0.3) and non-enforceable pH goal (7.7ฑ0.1) applied to DCWASA.
Based on recent compliance monitoring information (DCWASA 2005; 2006), DCWASA
was below the LCR lead action level for two consecutive 6-month monitoring periods in
2005 since commencing system-wide addition of orthophosphate in August 2004.
6.2 Possible Follow-on Evaluation
Follow-on evaluations could be conducted for the purpose of understanding further
factors that contributed to the occurrence of elevated lead levels at consumers' taps in
the DCWASA system. In addition, follow-on evaluations could be conducted for the
purpose of enhancing current understanding of the interrelationships of water chemistry
and scales on metals release in drinking water systems. Additional work activities that
could address these issues are described below.
6.2.1 DCWASA-Related Follow-on Evaluations
This section outlines suggested follow-on evaluations aimed at providing further
clarification with regard to specific conditions and events that contributed to elevated
lead levels in the DCWASA system. Suggested topics include the following:
Reduced pH and alkalinity in distributed water during 2001 - 2002
Consequences of partial and full LSL replacement
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6.2.1.1 Reduced pH and Alkalinity in Distributed Water during 2001 - 2002
The pH and alkalinity of finished water at the Dalecarlia and McMillan plants exhibited
seasonal variations and fluctuations during the study period from 1992 to 2004. The pH
and alkalinity of the distributed water generally followed the seasonal variations of the
finished water, except during 2001 - 2002 when the pH and alkalinity of the distributed
water were notably lower than the finished water discharged at the plants. The
occurrence of nitrification in the distribution system has not been documented by
DCWASA or USEPA Region 3 (Rizzo, 2005b). More research is therefore needed to
understand the cause of reduced pH and alkalinity in the distributed water during 2001 -
2002 and its possible impacts on lead release and corrosion control in the DCWASA
system.
6.2.1.2 Consequences of Partial and Full LSL Replacement
DCWASA has replaced a large number of lead service lines in the service area. Data
gaps exist regarding the effectiveness of partial lead service line replacement programs
on reducing lead levels at consumers' taps, and whether there are any short- or long-
term negative impacts such as elevated lead spikes or disturbance of existing scales.
This suggested follow-on work could improve understanding of the impact and
consequences of performing partial or full lead service replacements on lead release
and compliance with the LCR.
6.2.2 Research to Enhance Understanding of Lead Release
This section identifies follow-on evaluations that could enhance understanding of lead
release associated with a change in treatment and potentially could be applicable to
other utility situations. These suggested topics include the following:
Lead release in analogous systems following disinfectant change
Effectiveness of orthophosphate on lead scales
Effects of chloride and sulfate levels on lead release under chlorination,
chloramination, and a disinfectant change
Characterization of ORP as a function of disinfection regime and ORP impact on
lead scales
Improved understanding of the mechanisms and factors influencing the formation of
Pb (IV) scales
Impact of changes in treatment processes on lead scale formation and lead release
6.2.2.1 Lead Release in Analogous Systems following Disinfectant Change
This report considered the importance of the complex interrelationships of ORP and pH
on the predominance of Pb (II) or Pb (IV) in scales, and ultimately the release of lead from
LSL during a change in disinfectant in the DCWASA system. Aspects of these
interrelationships have been considered as contributing factors in metals release at other
systems such as Greater Cincinnati Water Works and City of Madison Water Utility
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(Schocketal., 2001; Lytle and Schock, 2005b). Further analysis of analogous drinking
water systems could be conducted by developing case studies to understand the
complex interrelationships of these water quality parameters and system conditions on
metals release associated with a change in disinfectant.
6.2.2.2 Effectiveness of Orthophosphate on Lead Scales
This report addresses the timeframe prior to system-wide application of Orthophosphate
inhibitor for corrosion control (i.e., prior to August 2004). Current information about
Orthophosphate effectiveness is based primarily on the presence and behavior of Pb (II)
species. Little information is currently available regarding interactions of Orthophosphate
with Pb (IV) species. Consequently, it is difficult to predict the impact of using
Orthophosphate for corrosion control during a transition between Pb (II) and Pb (IV)
regimes or under conditions in which Pb (IV) is the dominant species. More research is
needed to understand the interaction of Orthophosphate with different lead species and
corrosion scales.
6.2.2.3 Effects of Chloride and Sulfate Levels on Lead Release under Chlorination,
Chloramination, and a Disinfectant Change
The impact of the chloride and sulfate ratio on lead release is a topic that has not been
investigated for the DCWASA system, primarily because data were not available. This
topic is an area that warrants additional study to understand further the multiple and
competing factors, in conjunction with a disinfectant change, that impact lead release.
Chloride increases lead corrosion while sulfate appears to mitigate the corrosive effects
of chloride. Consequently, the chloride/sulfate ratio is recognized as an important
parameter in lead corrosion studies (Reiber et. al, 1997). Recent research, including
studies pertaining to both free chlorine and chloramines disinfection, also demonstrates
a correlation between chlorides, sulfates and lead release (Taylor et al., 2005; Tang et
al., 2006).
Proposed further work could include reviewing relevant data, if available, from other
systems that use water from Washington Aqueduct such as Fairfax and Arlington.
6.2.2.4 Characterization of ORP as a Function of Disinfection Regime and ORP
Impact on Lead Scales
There are data gaps in understanding the importance of ORP under different disinfection
regimes as discussed in Section 5. More information is needed about ORP conditions in
actual systems before, during, and after disinfectant changes. More information is also
needed on how changes in ORP increase or decrease metals release. Improved
understanding of the role of ORP on lead scale formation, passivation and water
chemistry conditions could provide utilities with needed operational information for
improved control of metals release.
6.2.2.5 Improved Understanding of the Mechanisms and Factors Influencing the
Formation of Pb (IV) Scales
The mechanisms of Pb (IV) formation are not well understood, as described previously in
this report. For example, Switzer et al. (2006) highlighted data gaps in the mechanisms
of PbO2 formation. Lytle and Schock (2005b) identified the need for more research to
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determine the ORP threshold for PbO2 stability, its solubility in relation to pH, and the
relationship to disinfectant type, residual, and oxidant demand in the pipe scale. .
Korshin et al. (2005) discussed the influence of natural organic matter on corroding lead
materials. Further fundamental research in these areas could enable a better
understanding of the conditions that most likely facilitate and maintain Pb (IV) formation
in drinking water systems.
6.2.2.6 Impact of Changes in Treatment Processes on Lead Scale Formation and
Lead Release
More research on the formation and stability of Pb (IV) scales under a variety of different
conditions is needed. Lytle and Schock (2005b) identified the need for elucidating the
decomposition pathway of PbO2 scales because serious problems potentially could
occur with treatment changes that result in lowering of the redox potential. Additional
research is therefore needed to understand how temporary and long-term changes in
disinfectant affect the formation of lead scale and short- and long-term lead release at
consumers' taps. Other possible treatment changes such as pH adjustment and
coagulant changes could potentially affect scales formation and stability. This
information could form the basis for developing decision-tools that utilities could use to
predict how treatment changes and chemical conditions will impact lead scales and lead
release.
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7. ABBREVIATIONS
|jg/L micrograms per liter
AC alternating current
AL action level
AO Administrative Order
DC District of Columbia (or direct current)
DCWASA District of Columbia Water and Sewer Authority
DS distribution system
EC electrochemical
GIS Geographic Information Systems
LCR Lead and Copper Rule
LSI Langelier Saturation Index
LSL lead service line
LSLR lead service line replacement
MCL maximum contaminant level
mg/L milligrams per liter
NE northeast
NOM natural organic matter
NSF National Sanitation Foundation
NW northwest
O&M operations and maintenance
OCCT Optimal Corrosion Control Treatment
ORP Oxidation Reduction Potential
OWQP Optimal Water Quality Parameters
PbO2 lead dioxide
PLSLR partial lead service line replacement
PO4 phosphate
POU point-of-use
ppb parts per billion
ppm parts per million
PQAPP Programmatic Quality Assurance Project Plan
SE southeast
SHE standard hydrogen electrode
SOP standard operating procedures
SW southwest
SWTR Surface Water Treatment Rule
TCR Total Coliform Rule
THM trihalomethane
TTHM total trihalomethane
USAGE United States Army Corps of Engineers
USEPA United States Environmental Protection Agency
WA Washington Aqueduct
WASUA Water and Sewer Utility Administration
WTP water treatment plant
WWTP wastewater treatment plant
89
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8. REFERENCES
AWWA (American Water Works Association). 2005. Managing Change and Unintended
Consequences: Lead and Copper Rule Corrosion Control Treatment. Denver, CO.
AwwaRF. 1990. Lead Control Strategies. Awwa Research Foundation and American
Water Works Association. Denver, CO.
AwwaRF. 1996. Electrical Grounding, Pipe Integrity and Shock Hazard. American
Water Works Association. Denver, CO.
Bell, G.E.G. 1998. Observation on the effect of grounding on water piping. Corrosion
(95), Orlando, FL.
Boyd, G.R., P. Shetty, A.M. Sandvig, and G.L. Pierson. 2004. Pb in tap water following
simulated partial lead pipe replacements. J. Environ. Eng. 130(10): 1188-1197.
Boyd, G.R., K.M. Dewis, A.M. Sandvig, G.J. Kirmeyer, S.H. Reiber, and G.V. Korshin.
2006a. Effect of Changing Disinfectants on Distribution System Lead and Copper
Release, Part 1: Literature Review, Awwa Research Foundation. Denver, CO.
Boyd, G.R., G.L. Pierson, G.J. Kirmeyer, M.D. Britton, and R.J. English. 2006b. Pb
Release from End-Use Plumbing Components. In Proc. of the AWWA Water Quality
Technology Conference, November 2006. Denver, CO.
Cantor, A.F., J.K. Park, and P. Vaiyavatjamai. 2003. Effect of Chlorine on Corrosion in
Drinking Water Systems. Journal AWWA, 95(5) 112-123.
CH2MHILL. 2004. Desktop Corrosion Control Study. Prepared for USEPA Region 3.
Philadelphia, PA. April 2004.
Clement, J.A. 1996. Review of Washington, D.C. Corrosion Control Recommendations.
Peer review of Corrosion Control Study (1996). Sent to G. Rizzo, USEPA Region 3,
December 13, 1996.
Colling, J.H., Whindcup, P.A.E., and C.R. Hayes. 1987. The measurement of
plumbosolvency propensity to guide the control of lead in tapwaters. Journal of the
Institute of Water and Environmental Management, 1 (2): 263-269.
DCWASA. 2003. Annual Report for the 2003 Lead Service Replacement Program.
September 2003.
DCWASA. 2004. Update of the Annual Report for the 2004 Lead Service Replacement
Program. October 8, 2004.
DCWASA. 2005. Lead & Copper Compliance Report, January - June 2005, October
14, 2005.
DCWASA. 2006. Lead & Copper Compliance Report, July - December 2005, May 3,
2006.
ECG, Incorporated. 1994. Corrosion Control Study. Study for the Mobile District, U.S.
Army Corps of Engineers, June 2004.
Edwards, M. 2003. Letter sent to G. Rizzo, USEPA Region 3, October 17, 2003.
90
-------
Edwards, M. and A. Dudi. 2004. Role of chlorine and chloramines in corrosion of lead-
bearing plumbing materials. Journal A WWA 96(10): 69-81.
Gardels, M.C. and T.J. Sorg. 1989. A laboratory study of the leaching of lead from
water faucets. Journal AWWA 81(7): 101.
Giani, R., M. Edwards, C. Chung, and J. Wujek. 2005a. Use of lead profiles to
determine source of action level exceedances from residential homes in Washington,
D.C. Internal Report for DCWASA.
Giani, R., M. Donnelly, and T. Ngantcha. 2005b. The effects of changing between
chloramine and chlorine disinfectants on lead leaching. In Proc. of the AWWA Water
Quality Technology Conference, November 2005, Quebec City, Quebec, Canada.
Grumbles, B. 2004. Memorandum to Regional Administrators - Water Division
Directors - Regions I-X: Lead and Copper Rule - Clarification of Requirements for
Collecting Samples and Calculating Compliance. November 23, 2004. Washington,
D.C.
Hopwood, J.D., Davey, R.J., Jones, M.O., Pritchard, R.G., Cardew, P.T., and A. Booth.
2002. Development of chloropyromorphite coatings for lead copper pipes. Journal of
Materials Chemistry, 12(6): 1717-1723.
International Studies and Training Institute Inc. (ISTI). 1995. Final Report: Sanitary
Survey of the Drinking Water Distribution System of the District of Columbia. Appendix
A, p.13-15.
Keefer, W. and R. Giani. 2005. Lead investigation: bronze water meters. Internal
Report for AwwaRF Project 3018. Washington, D.C.: DCWASA Water Quality Division.
Khanal, S.C., Shang, C., and Huang, J.C. 2003. Use of ORP (oxidation reduction
potential) to control oxygen dosing for online sulfide oxidation in anaerobic treatment of
high sulfate wastewater. Water Science Technology 47(12): 183-189.
Kiang, J.E. and E.R. Hagen. 2004. Preparing for extreme droughts: moving beyond the
historical planning event in the Potomac Basin. In Proc. of the World Water and
Environmental Resources Congress, sponsored by ASCE EWRI, Salt Lake City, UT,
June 27-July 1,2004.
Kirmeyer, G.J., G.R. Boyd, N.K. Tarbet, R. Serpente. 2000. Lead Pipe Rehabilitation
and Replacement Techniques. 176-177. Awwa Research Foundation. Denver, CO.
Korshin, G.V., J.F. Ferguson, and A.N. Lancaster. 2005. Influence of natural organic
matter on the properties of corroding lead surface and behavior of lead-containing
particles. Water Research, 39(5): 811-818.
Lin, N.H., A.Torrents, A.P. Davis, and M. Zeinali. 1997. Lead corrosion control from
lead, copper-lead solder, and brass coupons in drinking water employing free and
combined chlorine. Journal Environ Sci Health A32(4) 865-884.
Lytle, D.A. and M.R. Schock. 2000. Impact of stagnation time on metal dissolution from
plumbing materials in drinking water. Journal of Water Supply: Research and
Technology (49) 5: 243-257.
91
-------
Lytle, D.A. and M.R. Schock. 2005a. The formation of Pb (IV) oxides in chlorinated
water. In Proc. oftheAWWA Water Quality Technology Conference. November 2005,
Quebec City, Quebec, Canada.
Lytle, D.A. and M.R. Schock. 2005b. Formation of Pb (IV) oxides in chlorinated water.
Journal AWWA 97(11): 102-114.
Malcolm Pirnie Inc. 1998a. Caustic Soda Feasibility Study for Dalecarlia and McMillan
Water Treatment Plants. Prepared for WA U.S. Army Corps of Engineers, Baltimore
District.
Malcolm Pirnie Inc. 1998b. Corrosion Inhibitor Study for Dalecarlia and McMillan Water
Treatment Plants. Prepared for WA U.S. Army Corps of Engineers, Baltimore District.
Marani, D., G. Macchi, and M. Pagano. 1995. Lead Precipitation in the Presence of
Sulphate and Carbonate: Testing of Thermodynamic Predictions. Water Resources
(29): 1085-1092.
Maurice, P.A., Cabaniss, S.E., and Drummond, J. 2001. Climate induced changes in
the chemical characteristics of natural organic matter at a small freshwater wetland,
American Geophysical Union, Fall Meeting 2001. Abstract* B22C-0150.
Moser, M.R. 2006. Personal correspondence via e-mail on May 10, 2006 from M.
Rome Moser of Environomics to G. Boyd of HDR/EES, with spreadsheet attachment
entitled "Appendix graphs.xls" containing lead profile data collected in the DCWASA
system.
Odom, R. 2006a. Environomics Personal Communication via e-mail to G. Boyd of
HDR/EES, 07/27/2006, with document attachment entitled "EPA comments.doc"
containing lead profile data collected in the DCWASA system 2004-2006.
Odom, R. 2006b. Environomics Personal Communication via e-mail to G. Boyd of
HDR/EES, 07/27/2006, with spreadsheet attachment entitled "4th high sample analysis
7_28_04 (2).xls" containing WQP data collected in the DCWASA system in the 4th High
Pressure Zone, 4/5/2004 through 7/6/2004.
Reiber, S., S. Poulsom, S. Perry, M. Edwards, S. Patel, and D. Dodrill. 1997. General
Framework for Corrosion Control Based on Utility Experience. Awwa Research
Foundation. Denver, CO.
Reiber, S. and L. Dufresne. 2005. Effects of external currents and dissimilar metal
contact on corrosion from lead service lines, draft final report prepared for USEPA
Regions. November2005.
Reiber, S. and R. Giani. 2005. National impacts from DC's lead experience. In Proc. of
WEFTEC, Washington, D.C., Water Environment Federation, 5994-6014.
Rizzo, G. 2004. USEPA Region 3 / DCWASA Response: Recommendations from
Marc Edwards' Review of Corrosion Control Treatment for the District of Columbia Water
System, October 17, 2003, Spring 2004.
Rizzo, G. 2005a. Personal communication via e-mail from George Rizzo, USEPA
Region 3, to Kathy Martel, HDR/EES. May 9, 2005.
Rizzo, G. 2005b. Personal communication via e-mail from George Rizzo, USEPA
Region 3, to Kathy Martel, HDR/EES. March 30, 2005.
92
-------
Rizzo, G. 2006a. Personal communication via e-mail from G. Rizzo, USEPA Region 3,
to G. Boyd, HDR/EES. May 9, 2006.
Rizzo,G. 2006b. USEPA Region 3. USEPA/HDR conference call September 7, 2006.
Rizzo, G. 2006c. Personal communication via e-mail from G. Rizzo, USEPA Region 3,
to K. Smith, USEPA, Washington D.C. September 28, 2006.
Samuels, E.R. and J.C. Meranger. 1984. Preliminary studies on the leaching of some
trace metals from kitchen faucets. Water Research 18(1): 75.
Schock, M.R. 1999. Internal corrosion and deposition control. Chapter in Water Quality
and Treatment: A Handbook of Community Water Supplies, Fifth Edition. American
Waterworks Association: McGraw Hill, New York, NY.
Schock, M.R. 2005. Lead chemistry basics, scale formation, and corrosion control
treatment. Virginia Section ofAWWA Drinking Water Quality Seminar. April 13, 2005,
Richmond, VA.
Schock, M.R. I. Wagner and R.J. Oliphant. 1996. Corrosion and Solubility of Lead in
Drinking Water. Chapter 4 in Internal Corrosion of Water Distribution Systems. Second
Edition. American Water Works Association Research Foundation and DVGW-
Technologiezentrum Wasser. Denver, CO.
Schock, M.R., S.M. Harmon, J. Swertfeger, and R. Lohmann. 2001. Tetravalent lead: a
hitherto unrecognized control of tap water lead contamination. In Proc. of the AWWA
Water Quality Technology Conference. Denver, CO.
Schock, M.R. and C.H. Neff. 1988. Trace metal contamination from brass fittings.
Journal AWWA 80(11): 47.
Schock, M.R. and R. Giani. 2004. Oxidant/disinfectant chemistry and impacts on lead
corrosion. Sunday Workshop, AWWA Water Quality Technology Conference.
Schock, M.R., K. Scheckel, M. DeSantis, and T. Gerke. 2005. Mode of occurrence,
treatment, and monitoring significance of tetravalent lead. In Proc. ofAWWA Water
Quality Technology Conference. November 2005, Quebec City, Quebec, Canada.
Smith, K. 2006. Personal communication via e-mail from K. Smith, USEPA
Washington, D.C., to G. Boyd, HDR/EES, July 27, 2006.
Smith, K. 2007. Personal communication via e-mail from K. Smith, USEPA
Washington, D.C., to G. Boyd, HDR/EES, April 26, 2007.
StatSoft. 2006. Electronic Statistics Textbook, Web site accessed on May 23, 2006.
http://www.statsoft.com/textbook/stathome.html.
Steiner, R.C. and E.R. Hagen. 2000. Urban drought planning vs. the real thing. In
ASCE Water Resources.
Switzer, J.A., V.V. Rajasekharan, S. Boonsalee, E.A. Kulp, and E.W. Bohannan. 2006.
Evidence that monochloramine could lead to elevated Pb levels in drinking water.
Environ. Sci. Technol. 40(10): 3384-3387.
Symons, J.M., L.C. Bradley, Jr., and T.C. Cleveland. 2000. The Drinking Water
Dictionary. American Water Works Association.
-------
Tang, Z., S. Hong, W. Xiao, and J. Taylor. 2006. Impacts of blending ground, surface
and saline waters on lead release in drinking water distribution systems, Water
Research 40: 943-950.
Taylor, J., J. Dietz, A. Randall, S. Hong. 2005. Impact of RO-desalted water on
distribution water qualities. Water Science & Technology 51(6-7): 285-291.
U.S. Army Corps of Engineers (USAGE). 2006. Washington Aqueduct, Baltimore
District, Web site accessed on September 25, 2006. http://washingtonaqueduct.
nab.usace.army.mil/.
USEPA. 1991. Drinking Water Regulations; Maximum Contaminant Level Goals and
National Primary Drinking Water Regulations for Lead and Copper; Final Rule. 40 CFR,
parts 141 and 142. 56 Federal Register No. 110, June 7, 1991.
USEPA. 2000. Letter from USEPA, Jon M. Capacasa, to Thomas P. Jacobus, Chief
Washington Aqueduct, designating pH adjustment as OCCT. February 29, 2000.
USEPA Region 3. 2004a. Administrative Order for Compliance on Consent issued to
DCWASA on Lead Service Line Replacements. June 17, 2004.
USEPA. 2004b. 4th High Pressure Zone-Washington, D.C.
http://www.epa.gov/dclead/4th zone bnd.pdf. Web site accessed September 28, 2006.
USEPA. 2006. Corrosion Control, http://www.epa.gov/dclead/corrosion.htm. Web site
accessed September 28, 2006.
Van den Hoven, T.J. 1987. A new method to determine and control lead levels in tap
water. Aqua (6): 315-327.
Vasquez, F.A., R. Heaviside, Z. Tang, and J. Taylor. 2006. Effect of free chlorine and
chloramines on lead release in a distribution system. Journal A WWA 98(2): 144-154.
Volk, C., Wood, L, Johnson, B., Robinson, J., Zhu, H.W., and Kaplan, L. 2002.
Monitoring dissolved organic carbon in surface and drinking waters J. Environ. Monit.,
2002,4,43-47.
White, G.C. 1999. Handbook of Chlorination and Alternative Disinfectants, 4th ed., p.
965.
Wujek, J.J. 2005. Minimizing peak lead concentrations after partial lead service
replacements. Internal Report for AwwaRF Project 3018. Baker Killam Joint Venture.
94
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Appendix A
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Environomics Contract 68-C-02-042
Work Assignment WA 4-13
Final Report
Timeline
July 1992
District of Columbia Water and Sewer Authority (DCWASA) exceeded the lead action
level for the Jan. to June 1992 monitoring period, the first required round of Lead and
Copper Rule (LCR) compliance monitoring (source: July 16, 1997 correspondence from
USEPA Region 3 to DCWASA).
January 1993
District of Columbia Water and Sewer Authority (DCWASA) exceeded the lead action
level for the July to December 1992 monitoring period, the second required round of
LCR compliance monitoring (source: July 16, 1997 correspondence from USEPA Region 3
to DCWASA).
September 29,1993
Administrative Order (AO) issued to Water and Sewer Utility Administration (WASUA) for
acute and routine violations of the Total Coliform Rule (TCR) in September 1993.
WASUA was required to submit a plan for improving the flushing program.
October 15,1993
AO issued to the Washington Aqueduct (WA) for "virtual" violation of the TCR, i.e.,
numerous coliform positive samples at the entry points to the distribution system.
December?, 1993
Turbidity MCL violation at Dalecarlia water treatment plant (source: 1995 Sanitary
Survey of the Drinking Water Distribution System of the District of Columbia).
January 1994
DCWASA reported that the lead action level was exceeded for the July to Dec. 1993
monitoring period (source: COM memol2/12/03).
March 2,1994
AO issued to the WA due to a violation of the turbidity requirements of the Surface Water
Treatment Rule (SWTR). The AO required the WA to perform a Comprehensive
Performance Evaluation at the Dalecarlia and McMillan water treatment plants, and to
comply with the filtration, disinfection, reporting and public notification requirements of
the Safe Drinking Water Act. It also required the WA to develop a source water
monitoring program, to analyze capital improvement needs at both water treatment
plants, and to evaluate procedures for emergency notification of plant personnel.
June 1994
WA submitted a corrosion control report to USEPA Region 3 that recommended
optimum corrosion control treatment as pH control to maintain a positive Langelier
Saturation Index.
Final Report, May 31, 2007 A-1
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July 1994
WASUA reported that the lead action level was exceeded for the Jan. to June 1994
monitoring period (source: COM memol2/12/03, and DCWASA 90th percentile
calculations).
June 1995
WASUA recorded an acute Total Coliform Rule violation for E. coll (source: 1996 Follow-
Up Sanitary Survey of the Drinking Water Distribution System of the District of
Columbia).
October 1995
WASUA violated the TCP MCL (more than 5% of samples were total coliform positive)
(source: 1996 Follow-Up Sanitary Survey of the Drinking Water Distribution System of
the District of Columbia).
November 1995
WASUA recorded two acute violations of the TCP and USEPA Region 3 issued a
limited boil water notice for the areas involved (source: 1996 Follow-Up Sanitary Survey
of the Drinking Water Distribution System of the District of Columbia). Because of these
events, USEPA Region 3 issued an AO that requires a rational plan of action to improve
TCR compliance based on recommendations in the 1995 sanitary survey.
June 1996
WASUA violated the TCR MCL (more than 5% of samples were total coliform positive)
(source: 1996 Follow-Up Sanitary Survey of the Drinking Water Distribution System of
the District of Columbia).
July 1996
WASUA violated the TCR MCL (more than 5% of samples were total coliform positive)
(source: 1996 Follow-Up Sanitary Survey of the Drinking Water Distribution System of
the District of Columbia).
July 12,1996
AO issued to WASUA which incorporated the November 1995AO and the routine
monthly TCR violation in June 1996.
August 1996
WASUA violated the TCR MCL (more than 5% of samples were total coliform positive)
(source: 1996 Follow-Up Sanitary Survey of the Drinking Water Distribution System of
the District of Columbia).
July 16,1997
USEPA Region 3 conditionally designated Optimized Corrosion Control Treatment
(OCCT) as maintenance of a slightly positive Langelier Saturation Index through pH
adjustment (source: correspondence from USEPA Region 3 to WA and DCWASA
7/16/97). As a condition of this designation, USEPA Region 3 issued an AO for WA and
DCWASA to jointly assess the feasibility of alternate corrosion control treatment
including use of sodium hydroxide for pH control, and use of a non-zinc orthophosphate
corrosion inhibitor.
Final Report, May 31, 2007 A-2
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October 1,1996
DCWASA was created (note no longer named WASUA).
February 2000
USEPA Region 3 designated the use of pH adjustment as the OCCT for the
Washington Aqueduct and DCWASA. This designation required WA to maintain the
highest pH level attainable at the entry points to the distribution system without causing
excessive calcium carbonate precipitation in the distribution system. USEPA Region 3
designated that a minimum pH of 7.7 be maintained at the entry points to the distribution
system and at all tap samples within the distribution system (source: correspondence
from USEPA Region 3 to WA and DCWASA 2/29/00). USEPA Region 3 also reduced
the requirement for LCR tap monitoring to once per year at 50 sites during the period
June-September.
DCWASA established a supplemental monitoring plan to supplement the TCR
monitoring program focusing on worst-case areas (Source: 2002 Sanitary Survey).
November 1, 2000
WA initiated addition of chloramines for final disinfection in the distribution system,
replacing free chlorine addition (source: COM memo"!2/12/03).
November 1, 2000
WA converted from a dry alum feed system to a liquid alum feed system (source: COM
memo 12/12/03).
2000
Drought conditions may have affected source and finished water quality sufficiently to
affect lead solubility (source: COM memol2/12/03).
May 17, 2002
Retroactive to the monitoring period which began on July 1, 2000, USEPA Region 3
revised its designation of OWQP for minimum monthly pH at entry points to the
distribution system as follows: January (7.7), February (7.8), March (7.7), April (7.6),
May (7.5), June (7.4), July (7.4), August (7.4), September (7.4), October (7.5),
November (7.5), and December (7.6). Also, the minimum pH at distribution system tap
sample locations would change from 7.7 to 7.0 (source: correspondence from USEPA
Region 3 to WA and DCWASA 5/17/02).
Aug. 26, 2002
DCWASA reported that more than 10% of samples exceeded the lead action level of 15
ppb for the July 1, 2001 to June 30, 2002 monitoring period (samples collected July-Aug.
2001 and June 2002) (source: correspondence from DCWASA to USEPA Region 3).
May 20, 2003
DCWASA outlined its 2003 Lead Replacement Program in a letter to USEPA Region 3.
The program was accepted by USEPA Region 3 in a letter dated June 27, 2003.
DCWASA was required to replace 7% of its lead services per year as long as the system
continues to exceed the lead action level. In lieu of physical replacement, the
regulations allow service lines to be sampled to demonstrate that the water is below the
lead action level.
Final Report, May 31, 2007 A-3
-------
July 29, 2003
DCWASA reported that more than 10% of samples exceeded the lead action level for
the Jan. to June 2003 monitoring period (source: correspondence from DCWASA to
USEPA Region 3).
September 2003
DCWASA completed an initial inventory of lead service lines (Source: Report on the
Material Evaluation and Initial Inventory Sept. 2003). As of Sept. 30, 2002, there were
23,071 known lead service lines in the DC water distribution system.
October 2003
USEPA Region 3's independent corrosion expert found no reasons for DCWASA to not
implement phosphate addition for corrosion control but recommended additional studies
be conducted to further diagnose the DCWASA lead problem and proposed corrective
actions.
October 24, 2003
DCWASA reported that 385 lead services were physically replaced between 10/01/02
and 09/30/03, and 1,241 lead service lines were sampled in lieu of physical replacement
(source: DCWASA's Lead Service Replacement Program Annual Report for 2003).
January 2004
DCWASA developed a research strategy and presented it to WA, Arlington County, The
City of Falls Church, and USEPA Region 3.
January 26, 2004
DCWASA reported that more than 10% of samples exceeded the lead action level for
the July to Dec. 2003 monitoring period (source: correspondence from DCWASA to
USEPA Region 3).
February 2004
USEPA formed the Technical Expert Working Group to address the problem of elevated
lead levels.
April 30, 2004
USEPA Region 3 designated use of zinc orthophosphate for partial system application
in the 4th High Pressure Zone (source: correspondence from USEPA Region 3 to WA
and DCWASA 8/3/04).
May 28, 2004
USEPA Region 3 modified its April 30, 2004 designation of OCCT for the DC
distribution system to use orthophosphate instead of zinc orthophosphate for the 4th High
Pressure Zone (correspondence from USEPA Region 3 to WA and DCWASA 8/3/04).
June 1, 2004
The partial system application of orthophosphate to the 4th High Pressure Zone
commenced (source: correspondence from USEPA Region 3 to WA and DCWASA
8/3/04).
Final Report, May 31, 2007 A-4
-------
June 17, 2004
USEPA Region 3 issued an AO requiring DCWASA to develop a plan for updating its
materials evaluation used for sampling and its inventory of lead service lines, and a plan
for conducting follow-up sampling after partial replacement of a lead service line (Docket
No. SDWA-03-2004-0259DS).
July 6, 2004
DCWASA exceeded the lead action level for the Jan. to June 2004 monitoring period
(source: correspondence from DCWASA to USEPA Region 3).
August 3, 2004
USEPA modified the interim designation of OCCT for the DC distribution system to
consist of application of orthophosphate subject to stated conditions and water quality
parameters (source: correspondence from USEPA Region 3 to WA and DCWASA
8/3/04). This designation was slightly modified and clarified on September 8, 2004.
USEPA stipulated that the WA meet a pH goal of 7.7 ฑ0.1 for finished water leaving both
WTPs, and 7.7 ฑ0.1 for water samples from the distribution system during the
passivation period.
August 23, 2004
The Washington Aqueduct began feeding an orthophosphate corrosion inhibitor
(sources: DCWASA memo undated, CH2MHNI pH study report 11/30/04).
September 8, 2004
The interim designation of OCCT of August 3rd 2004 was slightly modified and clarified
(source: correspondence from USEPA Region 3 to WA and DCWASA 09/08/2004)
October 2004
DCWASA reported that 1,793 lead services were physically replaced between 10/1/03
and 9/30/04 (source: correspondence from DCWASA to USEPA Region 3 10/8/04).
November 30, 2004
A consultant completed a pH study report evaluating how WA can tighten pH control at
the two WTPs to meet the pH goal of 7.7 +/- 0.1 pH units. The report also includes
recommendations for reducing finished water turbidity at the Dalecarlia WTP (source:
CH2MHNI Report, 11/30/04).
January 2005
DCWASA exceeded the lead action level for the July to Dec. 2004 monitoring period
(source: DCWASA Lead and Copper Compliance Report).
January 14, 2005
USEPA Region 3 issued a supplemental AO to DCWASA related to lead service line
inventories, replacement program, sampling methodology and public notification.
(Docket No. SDWA-03-2005-0025DS).
June 2005
DCWASA met the LCR 90th percentile AL for the monitoring period Jan-Jun 2005.
December 2005
DCWASA met the LCR 90th percentile AL for the monitoring period Jul-Dec 2005.
Final Report, May 31, 2007 A-5
-------
Environomics Contract 68-C-02-042
Work Assignment WA 4-13
Final Report
Administrative Orders
The Administrative Orders (AOs) issued to the Washington Aqueduct (WA), the Water
and Sewer Utility Administration (WASUA) and District of Columbia Water and Sewer
Authority (DCWASA) are listed below in chronological order. WASUA was part of the
District of Columbia Department of Public Works until it was replaced by DCWASA on
October 1, 1996.
September 29,1993
An Emergency AO was issued to WASUA for acute and routine violations of the TCP in
September 1993. A copy is not available.
October 15,1993
An Emergency AO was issued to the Washington Aqueduct for "virtual" violation of the
TCP, i.e., numerous coliform positive samples were found at the entry points to the
distribution system. The AO required application of a filter aid chemical at the McMillan
water treatment plant, speciation of all fecal coliform positive samples, additional
monitoring at both water treatment plants' individual filters, Giardia and Cryptosporidium
monitoring at water treatment plant reservoirs, and development of a written protocol for
data review. This AO was superseded by the March 1, 1994 AO.
March 1,1994
An Emergency AO was issued to the Washington Aqueduct due to a violation of the
turbidity requirements of the Surface Water Treatment Rule (SWTR). It superseded the
AO dated October 15, 1993. The AO required the WA to perform a comprehensive
performance evaluation at the Dalecarlia and McMillan water treatment plants, and to
comply with the filtration, disinfection, reporting and public notification requirements of
the Safe Drinking Water Act. It also required WA to develop a source water monitoring
program, to analyze capital improvement needs at both water treatment plants, and to
evaluate procedures for emergency notification of plant personnel.
November 1995
Proposed AO issued to WASUA for previous violations of the TCP and to correct
deficiencies found in the 1995 sanitary survey. A copy of the final AO is not available
but its content is equal to the draft AO (per G. Rizzo of USEPA Region 3 in email to K.
Martel, 4/11/05).
July 12,1996
AO issued to WASUA which incorporated the November 1995 AO. The AO required
WASUA to notify the public of its November 1995 acute MCL violation and monthly MCL
violations of October 1995 and June 1996. WASUA was also required to develop the
following programs: public notification, financial management, flushing and disinfection,
storage tank maintenance and cross connection control.
A-6
-------
July 16,1997
USEPA Region 3 issued an AO for WA and DCWASA to jointly assess the feasibility of
alternate corrosion control treatment including use of sodium hydroxide for pH control,
and use of a non-zinc orthophosphate corrosion inhibitor.
June 17, 2004
USEPA Region 3 issued an administrative order requiring DCWASA to develop a plan
for updating its materials evaluation used for sampling and its inventory of lead service
lines, and a plan for conducting follow-up sampling after partial replacement of a lead
service line (Docket No. SDWA-03-2004-0259DS).
Jan. 14, 2005
USEPA Region 3 issued a supplemental administrative order to the June 17, 2004 order
discussed above. This order indicated that DCWASA had used an unapproved and
inappropriate method of five-minute flushing in determining whether some of the lead
service lines needed to be replaced. This order required that DCWASA determine how
many lead service lines had "passed" (meaning contributed less than 15 parts per billion
of lead), as presented in the September 2003 Annual Report for Lead Service Line
Replacement Program, using this incorrect methodology. Additionally, DCWASA was
required to determine how many of these lines had been replaced without being reported
to USEPA in 2003 and 2004. USEPA required DCWASA to physically replace lead
service lines equal in number to the number of LSLs passed in the 2003 report, less the
number that were physically replaced in 2003-2004. DCWASA was required to provide
notification to customers whose lead service lines had incorrectly passed due to using
the incorrect methodology. DCWASA shall (Docket No. SDWA-03-2005-0025DS).
A-7
-------
Environomics Contract 68-C-02-042
Work Assignment WA 4-13
Final Report
Summary of Sanitary Surveys
1995 Sanitary Survey of the Drinking Water Distribution System of the District of
Columbia
The 1995 survey was conducted from April to June. The survey objectives were to identify the
problems associated with bacteriological activity in the District of Columbia (DC) system and
provide recommendations to alleviate those problems. The survey included both the storage
facilities and the distribution system operated and maintained by WASUA and the WA Division
of the U.S. Army Corp. of Engineers. Laboratory data for 1993 through 1995 indicated elevated
bacteriological activity in service reservoirs and the DCWASA distribution system. The
distribution system reservoirs had not been drained and inspected in approximately 20 years,
and on-site inspections of the reservoirs revealed numerous sanitary deficiencies. Survey
findings included 185 recommendations that addressed treatment practices, cross connections,
distribution system O&M practices, consecutive systems, and operating procedures. Ninety one
recommendations were developed for reservoir facilities and operating conditions.
1996 Follow-Up Sanitary Survey of the Drinking Water Distribution System of the District
of Columbia
The 1996 survey was conducted during the month of September. Since the 1995 Sanitary
Survey Report was completed, the DC formed a new Regional Water and Sewer Authority
(WASA) to oversee operations of its water and sewer systems. Of the 185 recommendations in
the 1995 survey, 23 were fully completed, and 129 were under contract or part of a future plan.
Seven storage tanks were drained, cleaned, and inspected. An improved flushing program was
initiated. SOPs consistent with AWWA standards for water main disinfection practices were
developed. Numerous other engineering projects were underway, such as a reservoir
inspection program, design of reservoir improvements, clean/veil improvements, development of
O&M manuals, creation of a hydraulic model to evaluate system pressures, and plant process
control improvements.
1998 Follow-Up Sanitary Survey of the Drinking Water Distribution System of the District
of Columbia
A follow-up survey was conducted from July through September of 1998. Of the 185
recommendations identified during the 1995 Sanitary Survey, 77 were completed, and 31 had
not been addressed. For 15 of the 31 recommendations that were not addressed, some form of
corrective action had been taken, but this had failed to eliminate the sanitary risk. The
remaining 77 recommendations were under contract, planned for a future contract, under
consideration, or part of a long term plan. Findings from the 1998 Sanitary Survey related to
water quality monitoring included:
No coliform violations were observed between the summer of 1996 and the 1998
follow-up survey
The TCR sampling plan and sampling sites were approved as more representative of
distribution system water quality.
Final Report, May 31, 2007 A-8
-------
In terms of operations and maintenance, the 1998 survey found that WA and DCWASA
continued to make significant progress in distribution system rehabilitation work, which included
clearwell improvements; corrosion control evaluations; finished water reservoir cleaning,
inspection, improvements and operating procedures; development of flushing program, and
reduction in cross connection hazards. Training was provided to utility staff on flushing, pipe
and valve repair, water main disinfection, backflow prevention and cross-connection control.
Additional training recommended in the 1998 survey included:
Use of new O&M manuals and SOPs during training sessions,
Development of a written training program for coliform sampling,
Training for storage tank O&M, and
Training of new staff (e.g. flushing crews, inspectors).
1999 Sanitary Survey and Review of Turbidity Risk of the Washington Aqueduct
The 1999 sanitary survey of facilities owned by Washington Aqueduct (WA), conducted during
February and March, documented 73 potential sanitary risks. The major water quality
improvements that were identified as necessary to address the sanitary deficiencies are
summarized below. (Note: the responses in parentheses indicate whether the deficiency had
been addressed at the time of the 2003 survey.)
Need comprehensive watershed protection program for Dalecarlia Reservoir (no).
Develop and implement a comprehensive cross connection control program (no).
Update SOPs for WTP process operations and train operators on current procedures
(no).
Include coagulant aid and filter aid polymers in jar testing (yes).
Remove dead eels from open well at gatehouse at McMillan Reservoir (yes).
Initiate treatment plant valve exercising program (partially meets, all valves not
included in program).
Reduce amount of backlogged maintenance tasks with more focus on prioritizing
(partially meets, current process does not include prioritization).
Clean out WTP sedimentation basins on regular schedule (yes).
2002 Follow-Up Sanitary Survey of the Drinking Water Distribution System of the District
of Columbia
The 2002 survey was conducted from June through August. Of a total of 193 recommendations
identified during the 2002 survey, 8 were new recommendations, and 92 had been completed.
Twelve recommendations had been re-opened, primarily because facility O&M manuals had not
been used to train operations staff. At the time of the survey, the following observations were
made:
Since the original sanitary survey in 1995, all water storage facilities have been
cleaned and inspected and most have been completely rehabilitated. The two
remaining storage facilities that require major maintenance are under contract.
In May of 1999, the Water Quality Division established a 16-person flushing team to
conduct unidirectional flushing of the entire distribution system every 2 years.
Recommendations related to the flushing program included modifications to address
problem areas, hydrant operating procedures, pressure monitoring, establishment of
programs to address dead-ends and blow-offs.
WA made no progress on a cross-connection control program. DCWASA
established a cross-connection control program, but staff shortages limited program
implementation.
Final Report, May 31, 2007 A-9
-------
Since chloramination began in November 2000, an increase in total coliform
positives was observed each year.
Staff training is needed on storage tank O&M, facility O&M manuals, on-site
inspections, and distribution system operator certification.
Total coliform sampling sites should be reevaluated to assure they represent
distribution system conditions and are not influenced by biofilms present in building
plumbing.
There is a need for an integrated database that could store all data and process
information related to water quality and system operations.
October 17, 2003 Sanitary Survey of the Washington Aqueduct Draft Report
A sanitary survey of the facilities owned by WA (including intake works on the Potomac River,
transmission mains, two WTPs, and pumping stations) was conducted for USEPA Region 3 by
the Cadmus Group. Finished water storage and the distribution system were not included in the
scope of this survey. The sanitary survey team also conducted an optimization evaluation of the
two WTPs based on turbidity data from July 2002 to June 2003. Of 37 sanitary deficiencies
identified, the 9 highest priorities included:
Develop and implement a comprehensive cross connection control program,
including procedures for tagging and inspecting devices.
Establish an optimization program for each WTP, including detailed filter evaluations.
Update SOPs for WTP process operations and train staff on current procedures.
Install an automatic switchover system for the chlorine feed system at the Dalecarlia
WTP.
Formalize new solids handling plan for Dalecarlia WTP and incorporate it into SOPs.
Always add PAC1 as a primary coagulant at McMillan WTP due to the presence of
two open reservoirs between the alum addition point and the treatment plant.
Move sampling ports for turbidimeters on individual filters so they monitor total filter
effluent.
Develop procedures to minimize hydraulic changes in filter operations during
backwash.
Properly seal clearwell openings to reduce the chance of material entry. Improve
clean/veil vent termination points to minimize vandalism and animal entry (screening).
Final Report, May 31, 2007 /4-10
-------
Environomics Contract 68-C-02-042
Work Assignment WA 4-13
Final Report
Supplement to History and Evaluation of Lead Monitoring Program
USEPA Region 3 provided HDR/EES with laboratory sample reports, 90th percentile
calculations and correspondence related to Lead and Copper Rule (LCR) monitoring,
including first draw and second draw samples. HDR/EES reviewed 90th percentile
calculations prepared by DCWASA and checked them against original laboratory
reports. The results of this analysis are discussed in the main body of the report. This
appendix lists numbers of LCR monitoring sites that exceeded the action level in each
monitoring period. Separate tables are provided for first draw samples (Table 1) and
second draw samples (Table 2).
First Draw Lead Results
Table 1 shows the number of DCWASA sample sites where lead concentrations were
measured at levels higher than 15 u,g/L and how many of those sites exceeded the
Action Level in two or more LCR monitoring periods.
Table 1 First Draw Lead Samples -
ListinCI Of Samr>l'a SitPQ Whprp I par! I P\/P|Q Wprp ^> 1 R i in/I
i_i JIM ly \ji i_rui
Monitoring P6riod
J an u a'ry"- J u neฐ1 992" "
July - December 1992
January- June 1993
July - December 1993
January- June 1994
July - December 1994
January- June 1997
July - December 1997
July - December 1998
January- June 1999
July- Sept. 1999
July 2000 -June 2001
Revised July 2000-June
2001
by USFPA Region 3
July 2001 -June 2002
January- June 2003
July - December 2003
January - June 2004
July - December 2004
...... _.... ....... .....
Number of Sample Sites
Exceeding Action Level of
15 ua/L
16 M9
28
5
23
9
8
5
5
4
3
3
4
9
26
30
35
73
40
... ...... . . r.-,,
Number of Sample
Exceeding Action Level
More LCR Monitoring
Sites
in Two or
Periods
15
4
15
7
7
3
3
3
1
2
4
9
22
20
28
30
24
Final Report, May 31, 2007
A-11
-------
Second Draw Lead Results
Table 2 lists the addresses for sample sites where lead concentrations of second draw
samples were measured at levels higher than 15 u,g/L and how many of those sites
exceeded the Action Level in two or more LCR monitoring periods.
Table 2 Second Draw Lead Samples -
Listing of Sample Sites Where Lead Levels Were > 15 u.g/L
Monitoring Period
January- June 1997
July-Dec. 1997
July-Dec. 1998
January- June 1999
July-Sept. 1999
July 2000 -June 2001
July 2000 -June 2001
(revised bv USEPA Reaion 3)
July 2001 -June 2002
January -June 2003
July-Dec. 2003
January -June 2004
July-Dec. 2004
Number of Sample Sites
Exceeding Action Level
of 15ug/L
4
4
3
3
5
3
9
24
17
29
63
35
Number of Sample Sites
Exceeding Action Level in
Two or More LCR
Monitoring Periods
2
4
2
1
4
3
9
24
15
26
25
21
Final Report, May 31, 2007
A-12
-------
Environomics Contract 68-C-02-042
Work Assignment WA 4-13
Final Report
Summary of Corrosion Control Studies
June 1994 Corrosion Control Study (EGG, Inc.)
The purpose of this corrosion control study was to determine the most effective treatment
approach to control lead and copper corrosion in drinking water supply lines. The study
included a desktop study, a screening evaluation of corrosion inhibitors using jar testing, and
full-scale pipe loop experiments. Technical and cost constraints were identified for specific
corrosion control treatment alternatives. The desktop study found that optimizing the pH and
alkalinity was intrinsically related to the calcium hardness adjustment and calcium carbonate
precipitation potential. The results of the screening evaluation showed that zinc orthophosphate
demonstrated lower dissolved lead concentrations in the static system than the silicates,
polyphosphates or straight orthophosphate. Both the silicates and the polyphosphates actually
showed elevated dissolved lead concentrations when compared with the control conditions.
Three pipe loop models were constructed to test finished water at the Dalecarlia water treatment
plant. One model was used to test a zinc orthophosphate (1:5 ratio); a second model was used
to test a pH/alkalinity/calcium hardness adjustment, and a third model served as a control (no
corrosion control inhibitor or water quality adjustment implemented). These pipe loops were
monitored for lead and copper concentrations in standing and flowing water samples, as well as
for direct metal corrosion from coupons and inserts over a 10-month study period. The second
pipe loop (pH/alkalinity/calcium hardness adjustment alternative) had severe calcium carbonate
deposition problems. Zinc orthophosphate showed lower corrosion rates and reduced lead
concentrations in the water in 84% of days studied; however, the use of zinc orthophosphate
system-wide must be questioned due to discrete samples with elevated lead concentrations,
overall costs, and downstream treatment of phosphorous and zinc.
The study concluded that WA water treatment plants should optimize current practices by
maintaining a consistent pH level, which would optimize the Langelier Saturation Index in the
positive range, as close to zero as possible. Further, it was recommended that WA calculate
Calcium Carbonate Precipitation Potential (CCPP) in the distribution system on a daily basis
after treatment with the goal of keeping the CCPP at or near 0; (the study determined that it was
not feasible to obtain CCPP levels between 4 and 10). The study noted that further research
was needed to study the optimal balance of corrosion control, scaling and trihalomethane
formation potential.
Dec. 1996 Expert Review (Jonathon Clement)
An expert review, commissioned by USEPA, was conducted to review the June 1994 corrosion
control study and supplemental system information, including a sanitary survey, pipe material
information and water quality data for the period of September 1995 to August 1996 (pH,
alkalinity, chlorine, and calcium). The selection of corrosion control strategy was driven by the
high percentage of unlined cast iron pipe in the DCWASA system (approximately 73% of total
miles of main). Comments were based primarily on the supplementary information. Two viable
treatment strategies for lead control included: (1) stabilize and increase the pH to 9.0, and (2)
maintain the pH between 7.4 and 7.8 and add orthophosphate. The use of orthophosphate was
not recommended unless site-specific testing was conducted with unlined cast-iron pipe loops,
Final Report, May 31, 2007 /4-13
-------
constructed with DCWASA distribution system mains, to determine the effects of
orthophosphate on iron release and red water. The alternative of pH adjustment to 9.0
appeared to be more appropriate; however, potential issues with calcium precipitation, THM
formation potential and water disposal issues (higher pH) required further evaluation.
Additionally, the recommendations indicated that, regardless of treatment selection, maintaining
a consistent distribution system pH should be addressed. The study recommended avoiding pH
variations of more than 0.5 pH units.
Jan. 1998 Caustic Soda Feasibility Study (Malcolm Pirnie)
This feasibility study, conducted for the Washington Aqueduct, addressed Conditions 1a and 1b
of the conditional designation of Optimum Corrosion Control Treatment, dated July 16, 1996.
This condition required WA and DCWASA to determine the feasibility of switching from lime to
sodium hydroxide to control pH. The feasibility assessment included: (part 1a) a determination
of the highest pH that could be maintained using sodium hydroxide without causing exceedance
of the total trihalomethane MCLs and excessive precipitation of calcium carbonate in the
distribution system, and (part 1b) estimation of construction costs and annual O&M costs for the
sodium hydroxide feed system. A spreadsheet model was used to estimate the maximum pH
that could be maintained using lime or caustic soda while preventing excessive precipitation of
calcium carbonate. The modeling results indicated that excessive calcium carbonate
precipitation using caustic soda would begin at pH 0.2 units higher than when using lime.
Additionally, modeling results indicated that excessive precipitation would occur if a pH of 8.5
was maintained throughout the year for either lime or caustic soda. Caustic soda would provide
some benefits in terms of process control and maintenance requirements. Disinfection by-
product levels were estimated to be the same whether caustic soda or lime was used. The
chemical cost of caustic soda was approximately 6.5 times higher than lime for a desired target
finished water pH of 7.4, and was approximately 5.0 times higher than lime for a desired target
finished water pH of 8.5. The capital cost of the caustic soda feed system was estimated at
$720,000 (1997 dollars).
May 1998 Corrosion Inhibitor Study for Dalecarlia and McMillan Water Treatment Plants
(Malcolm Pirnie)
The corrosion inhibitor study, conducted for the Washington Aqueduct, included three primary
tasks: (1) determine the approximate corrosion inhibitor dosage rate; (2) estimate phosphate
levels in wastewater; and (3) estimate capital and O&M costs for the corrosion inhibitor feed
system. The consultant also reviewed the current literature and immersion tests conducted by
ECG Inc. to compare the relative benefits of zinc orthophosphate and orthophosphate
(phosphoric acid). The study concluded:
1. Zinc orthophosphate does not provide any long-term benefits over orthophosphate in
controlling lead levels in the water.
2. The chemical costs for zinc orthophosphate are approximately twice the chemical costs
for orthophosphate.
3. If WA decides to use corrosion inhibitors as a lead control strategy, orthophosphate
should be used at a dosage rate of 1.0 mg/L as PO4.
4. Assuming a phosphate dose of 1.0 mg/L as PO4, the maximum phosphate concentration
to reach the wastewater treatment plant would be approximately 1.0 mg/L as PO4, which
would result in a 10% increase in phosphorous levels at the wastewater treatment plant
under the worst case scenario.
5. The total estimated capital costs for an orthophosphate feed system are $350,000 and
$220,000 for the Dalecarlia and McMillan plants, respectively.
Final Report, May 31, 2007 /4-14
-------
6. The annual O&M costs of orthophosphate are $166,000 and $148,000 for the Dalecarlia
and McMillan plants, respectively. The annual cost savings due to reduction in lime
usage is approximately $30,000 for each plant.
Oct. 2003 Expert Review - Draft Report (Marc Edwards)
This expert review, conducted for USEPA Region 3, was based on an extensive literature
review and a few experiments. The report found no reasons for DCWASA torrol implement
phosphate addition for corrosion control but recommended that additional studies and corrective
actions should be conducted to further diagnose the DCWASA lead problem. The report also
indicated that it could not be determined whether phosphate addition would address the lead
problem. The following prioritized action items were recommended for mitigating the lead
problem:
a. Compare LCR sampling protocols for the seven utilities treating Potomac River water,
and compare samples for the old and new sampling protocols. Determine if the new
sampling protocol mobilizes more paniculate lead. Check use of filtration devices on
kitchen taps at LCR sampling sites, and document sampling procedures used at these
sites.
b. Initiate a corrosion study of brass, pure lead and lead-solder coupled to copper to
evaluate galvanic corrosion, chloramine corrosion and the combined effect of nitrate and
chloramine on each lead-bearing material.
c. Conduct a filtration analysis of solids present in the DCWASA system and try to
determine their source.
d. Conduct a study or review existing data, if available, on nitrification events in the
DCWASA system and sister systems served by the Dalecarlia water treatment plant.
e. Examine historical data on lead, copper and zinc loading to the sewage treatment plant
from the DCWASA system, before and after chloramine disinfection was initiated
(November 2000).
f. Examine whether DCWASA's practice of switching disinfectants each Spring (from
chloramine to free chlorine) adversely affects corrosion control.
Spring 2004 USEPA Region 3 /DCWASA Response to Edwards' Recommendations
This paper was developed to provide background information for DC city council and
congressional hearings during 2004. This response included the following information with
respect to the Expert Review from 2003:
DCWASA has initiated a plan to study corrosion rates of brass, pure lead and lead
solder before and after corrosion control treatment.
DCWASA has collected filtrate samples and will have them analyzed per
recommendation.
DCWASA has conducted monitoring for parameters that would indicate the occurrence
of nitrification. The sampling effort has not found evidence of nitrification in the system.
A review of wastewater treatment plant data has indicated that no significant increase in
lead, copper, or zinc levels occurred after conversion to chloramine.
April 2004 Desktop Corrosion Control Study (CH2MHMI)
This study reviewed water quality changes in WA customers' distribution systems and
engineering reports on corrosion control and LCR compliance strategies. Corrosion control
options that are evaluated included: (1) maintaining a constant, high pH at the two water
treatment plants using either quicklime (current practice) and/or sodium hydroxide, and (2)
feeding a corrosion inhibitor such as orthophosphate while maintaining a constant pH of about
7.7 throughout the year.
Final Report, May 31, 2007 /4-15
-------
Mathematical modeling conducted for this study found that adjustment of finished water pH to
8.5 resulted in severely elevated levels of calcium carbonate precipitation potential, indicating
that excessive calcium precipitation would occur. The report concluded that pH adjustment to
pH 8.8 year-round is not advisable for the Washington Aqueduct.
The report concluded that orthophosphate appears to be the "reoptimized" best treatment for
Washington Aqueduct. However, further testing was recommended using partial system
application of phosphoric acid. The report also recommended that the Washington Aqueduct
conduct pilot-scale testing using pipe loops of DCWASA lead service lines to help determine
optimal corrosion inhibitor feed rates. The Optimum Corrosion Control Treatment document
was prepared and submitted to USEPA for approval.
July 2004 Evaluation of Orthophosphate Addition Effects on Microbial Water Quality
(Anne Camper)
The purpose of this technical memo was to address four specific questions posed by Cadmus.
The four questions and answers are summarized below.
1. Considering DCWASA's distribution system infrastructure and water quality, do
you believe that orthophosphate addition will help control bio film growth? More
specifically, how will the addition of orthophosphate affect TCP compliance? It is
probable that phosphate addition will have a beneficial effect on regrowth in the
DCWASA system in the long term. In the short term, there may be some elevated
bacterial counts. In areas of the distribution system that were not flushed prior to
phosphate addition, increased bacterial counts are probable.
2. What detrimental effects could there be in a distribution system such as
DCWASA's from maintaining an orthophosphate residual of 3 mg/L? The only
potential effect on microbial growth/biofilms would be the rate at which surfaces are
impacted by the corrosion inhibitor and the time required to reach equilibrium.
3. Can the Aqueduct reduce the disinfectant residual concentration in the DCWASA
distribution system without adversely impacting TCP compliance? If corrosion
control has a positive impact on microbial counts, it is possible that the chloramines
dose can be reduced, as long as dead ends and low flow areas continue to have a
measurable residual.
4. DCWASA practices unidirectional flushing in their distribution system and
routinely flushes the entire system approximately every two years. How important
is unidirectional flushing for the DC distribution system? In your opinion, how
often should WASA flush their entire system? Flushing should be considered as
part of DC's program to improve microbial water quality. Because of the predominance
of unlined cast iron pipes in the DC system, flushing is critical for maintaining water
quality, particularly in low flow areas where loose deposits accumulate. It is difficult to
determine flushing frequency as it depends on many factors including water quality, cost,
historical flushing practices, personnel resources, water availability during drought
conditions, and disposal of flushing water.
Nov. 2004 pH Study Report for Washington Aqueduct (CH2M Hill)
The purpose of this report was to evaluate alternatives and recommend process changes for
achieving optimized pH control at the Dalecarlia and McMillan water treatment plants. Four
Final Report, May 31, 2007 /\-16
-------
alternatives were evaluated: (1) optimize existing pH control equipment; (2) replace existing lime
slakers with batch-type slaker systems; (3) trim final pH with caustic while continuing to use lime
for base load pH adjustment; and (4) replace lime feed with caustic feed. Recommendations
were based on the third alternative: trim final pH with caustic and use lime for base pH
adjustment. The report recommended that the existing lime feeders be replaced with properly
sized feeders to improve control of lime feed.
Effects of External Currents and Dissimilar Metal Contact on Corrosion and Metals
Release From Lead Service Lines (HDR and Cadmus)
The purpose of this project was to use laboratory-scale testing rigs to identify whether grounding
and/or galvanic currents can have a significant and prolonged impact on metals release from
lead service lines and leaded-brass appurtenances. Different forms of grounding currents (AC
vs. rectified) were impressed on both scaled and un-scaled lead service lines used in the testing
rigs. Galvanic currents were generated using the coupling of different lengths of copper tubing
to the lead service lines while the surface potential was measured. The testing was not
intended to replicate distribution system conditions but to evaluate various scenarios that
generate the highest possible metal release and the greatest lead service line surface effects.
The draft final report on this project was issued in November 2005.
Technical Support on Nitrification Inhibition From Zinc (Virginia Military Institute and
Cadmus)
This project was a preliminary step towards assessing the potential impacts of zinc-phosphate,
a proposed corrosion control chemical for drinking water, on the operation of the Arlington
County (VA) wastewater treatment plant. More specifically, this project evaluated the
concentration of zinc that could be tolerated by the biological nitrogen removal processes at the
wastewater treatment plant. The findings of this project will help determine whether or not zinc
at the proposed zinc orthophosphate dose would have an adverse impact on biological nutrient
removal processes at the Arlington plant. The project consists of bench scale studies as well as
a brief literature review. The estimated final report on this project was issued in September
2005.
Characterization of Natural Organic Matter in DC Drinking Water (Univ. Washington and
Cadmus)
The purpose of this project was to characterize the properties and reactivity of NOM, including
seasonal variations, in the raw and treated water to improve understanding of DBP formation,
the effectiveness of existing treatment on NOM removal, and the role of NOM in metal solubility.
Project activities include sample collection and laboratory-scale studies. The final report on this
project was issued in May 2006.
(On-going) Proposed Flow-Through, Lead Pipe Loop Test Plan (CH2MHMI)
The primary purpose of the pipe loop testing at the Washington Aqueduct is to evaluate the
effectiveness of alternate corrosion control strategies on reducing lead concentrations in DC
drinking water. A comparison of the effectiveness of two alternate corrosion inhibitors
(phosphoric acid and zinc orthophosphate) will be conducted. Finished water produced at the
WA's Dalecarlia WTP will be used as the source water for the testing. Samples of lead service
lines excavated from the DCWASA system will be used to construct the proposed pipe loops.
Final Report, May 31, 2007 /\-17
-------
(On-going) Evaluation of Potential Mechanisms of Lead Release Related to Conversion
from Free Chlorine to Chloramines and Evaluation of Scale from Lead Service Line
Specimens Excavated from the DCWASA System.
The USEPA has evaluated the potential mechanism of lead release in the DCWASA system by
conducting theoretical evaluations and laboratory studies related to the solubility of potential
lead solids that may be present in the system based on water quality conditions and by
evaluating the scale components from several lead service line specimens excavated from
DCWASA's distribution system. Results of these evaluations have been presented at the
AWWA Water Quality Technology Conferences in 2001 and 2004 (Schock, 2001; Schock and
Giani, 2004) and in a presentation to the Virginia Section of AWWA in April 2005 (Schock, 2005)
and are summarized here. These presentations indicate that a mechanism potentially
responsible for the change in lead levels with the conversion from free chlorine to chloramines
relates to the solubility of Pb (II) vs. Pb (IV) pipe scales. Control of lead in drinking water has
generally been presumed to be controlled by Pb (II) solids that form on lead containing materials.
Pb (IV) has a lower theoretical solubility than Pb (II) carbonate solids, and its presence may result
in relatively low lead levels. USEPA has evaluated the theoretical formation of Pb (IV)
compounds, which can form under relatively high oxidation-reduction (ORP) potentials, and the
lower ORP of chloraminated water when compared to water with free chlorine (Schock, 2001;
Schock and Giani, 2004; Schock, 2005).
By switching to chloramines, the ORP of the DCWASA water may have been lowered, causing
Pb (IV) solids to convert to more soluble Pb (II) solids and resulting in release of lead and higher
lead levels measured at the tap. This mechanism, along with supporting theoretical, laboratory,
and field water quality and scale analysis data are summarized in these papers and
presentations, including evidence of the presence of Pb (IV) solids in lead service line pipes
excavated from the DCWASA system prior to the switch to chloramines. These LSI specimens
primarily contained Pb (IV) compounds (plattnerite and scrutinyite) with only traces of Pb (II)
compounds (cerrusite and hydrocerrusite). In addition, lead levels, measured in residential
homes in the DCWASA system, decreased during a one-month switch to free chlorine in April of
2004 when compared to lead levels from the same sites during chloramination. The USEPA is
continuing with these investigations.
Final Report, May 31, 2007 /4-18
-------
Environomics Contract 68-C-02-042
Work Assignment WA 4-13
Final Report
Summary of Lead Service Line Replacement Program
From 2002 - 2005, DCWASA was required to replace 7% of the lead service lines in the system
each year due to exceedances of the lead action level.
Sept. 2003 Report on the Materials Evaluation and Initial Inventory
In September 2003, DCWASA updated its inventory of lead service lines and estimated that of
the system's 120,000 service connections, 23,071 were lead service lines (count as of
September 30, 2003).
Inventory of Lead Service Lines (2004 map)
DCWASA developed a map at a scale of 1:16,000 that shows the approximate locations of lead
service lines in the distribution system, based on the initial inventory conducted in 2003. Of the
estimated 23,071 lead service lines in the system, the map presents those that could be
geocoded. In Task 6, this map will be reviewed as part of an evaluation of lead levels in the
system.
2003 Sampling Results of Lead Service Lines (2004 map)
DCWASA developed a map in 2004 at a scale of 1:16,000 that shows lead sampling results for
lead service lines. The map delineates sample results less than or equal to 15 ppb, sample
results between 15 ppb and 300 ppb, and sample results greater than or equal to 300 ppb. In
Task 6, this map will be used, along with distribution system water quality data, to determine if
there is a statistically significant correlation between elevated lead levels and other water quality
parameters, such as pH, for different geographical areas.
Oct. 24, 2003 Annual Report of DCWASA's Lead Service Line Replacement Program
On October 24, 2003, DCWASA reported that during the period October 1, 2002 to September
30, 2003 it had replaced 385 lead service lines through physical replacement including 79 "full"
replacements and 306 "partial" replacements. A "partial" replacement means that something
other than the entire length of the service line is replaced (Code of Federal Regulations, Title
40, ง 141.84(d)). Title 40 CFR ง141.84 requires that a public water system replace the portion
of the lead service line owned by the system, but does not require that the system bear the cost
of replacing portions of the line that the system does not own.
2003-2004 Replacement of Lead Service Lines (2004 map)
DCWASA developed a map at a scale of 1:16,000 that shows both completed lead service line
replacements and those planned to be replaced in 2004. This map shows that 524
replacements had been completed and 817 were scheduled for 2004.
Oct. 8, 2004 Annual Report DCWASA's Lead Service Replacement Program
DCWASA reported that it had replaced 1,793 lead service lines between October 1, 2003 and
September 30, 2004.
Final Report, May 31, 2007 /4-19
-------
Environomics Contract 68-C-02-042
Work Assignment WA 4-13
Final Report
Summary of Correspondence on Designation of Optimal Corrosion Control
Treatment
July 16,1997
USEPA Region 3 conditionally designated Optimized Corrosion Control Treatment (OCCT) as
maintenance of a slightly positive Langelier Saturation Index through pH adjustment. As a
condition of this designation, USEPA Region 3 issued an Administrative Order (AO) for WA and
DCWASA to jointly assess the feasibility of alternate corrosion control treatment including use of
sodium hydroxide for pH control, and use of a non-zinc orthophosphate corrosion inhibitor.
USEPA Region 3 set a deadline of September 15, 1997 for completing the assessment.
August 15,1997
DCWASA responded to USEPA Region 3's July 16, 1997 letter outlining plans for WA to
conduct studies on corrosion control treatment and DCWASA to conduct studies on the effects
of these treatments on wastewater plants. WA will conduct studies on sodium hydroxide
including estimation of construction costs and O&M costs for a sodium hydroxide and
phosphate feed systems. The letter acknowledges the Sept. 15, 1997 deadline for these
studies.
September 4,1997
WA responded to USEPA Region 3's July 16, 1997 letter outlining the same proposed and on-
going studies outlined by DCWASA in their Aug. 15, 1997 letter. WA revised the estimated
schedule for completing these studies to be November 1, 1997 for the caustic soda studies and
March 1998 for the phosphate studies.
February 29, 2000
USEPA Region 3 designated the use of pH adjustment as the OCCT for the WA distribution
systems which required the WA to maintain the highest pH level attainable at the entry points to
the distribution system without causing excessive calcium carbonate precipitation in the
distribution system. USEPA also designated that a minimum pH of 7.7 be maintained at the
entry points to the distribution system and at all tap samples within the distribution system.
USEPA Region 3 also reduced the requirement for LCR tap monitoring to once per year at 50
sites.
May 1,2000
In response to USEPA Region 3's Feb. 29th letter, DCWASA proposed modifications to the
Optimal Water Quality Parameters. The proposed modifications were developed jointly by WA,
DCWASA and USEPA Region 3. Specifically, the proposed modifications would allow the
minimum finished water pH requirement to change monthly to account for seasonal changes in
untreated water quality as follows: January (7.7), February (7.8), March (7.7), April (7.6), May
(7.5), June (7.4), July (7.4), August (7.4), September (7.4), October (7.5), November (7.5), and
December (7.6). Also, the minimum pH at distribution system sites would change from 7.7 to
7.0, and would be measured at 12 sites vs. 10 sites proposed by USEPA Region 3.
Final Report, May 31, 2007 A-20
-------
May 3, 2000
In response to USEPA Region 3's Feb. 29th letter, WA proposed modifications as outlined in
DCWASA's May 1st letter. One additional suggestion was that the proposed Optimal Water
Quality Parameters be made effective for the 6 month monitoring period beginning July 1, 2000.
May 17, 2002
USEPA Region 3 revised its designation of OWQP with respect to the minimum monthly entry
point pH requirements per proposed levels requested by DCW ASA and WA in May 2000, noting
that the decision had been verbally agreed between WA and USEPA Region 3 in 2000. The
decision was made effective from the LCR monitoring period which began on July 1, 2000, The
OWQP for the distribution system tap samples was changed to a minimum pH of 7.0.
April 30, 2004
USEPA Region 3 designated use of zinc orthophosphate for partial system application in the 4th
High Pressure Zone.
May 28, 2004
USEPA Region 3 modified its April 30, 2004 designation of OCCT for the DC distribution
system to use orthophosphate instead of zinc orthophosphate for the 4th High Pressure Zone.
Aug. 3, 2004
USEPA Region 3 modified the interim designation of OCCT for the DCWASA distribution
system to consist of application of orthophosphate subject to stated conditions and water quality
parameters (source: correspondence from USEPA Region 3 to WA and DCWASA 8/3/04).
Specifically, USEPA Region 3 has stipulated that the WA will meet a pH goal of 7.8 +/-0.1
(7.7+/-0.1 per later revisions August 20, 2004 and September 7, 2004) for finished water leaving
both water treatment plants, and 7.7 +/-0.1 for water samples from the distribution system
during the passivation period.
Final Report, May 31, 2007 A-21
-------
LEAD PROFILES
Final Report, May 31, 2007 A-22
-------
Profile
No.
Date of
profile
Profile
Quadrant
Special Profile Conditions
Profiles Collected during Chloramination
1
2
3
4
5
6
7
8
9
10
11
12
13
14
12/8/2003
12/15/2003
1/5/2004
1/13/2004
2/9/2004
2/24/2004
3/2/2004
3/9/2004
3/16/2004
3/24/2004
3/24/2004
3/30/2004
3/31/2004
4/1/2004
NW
NW
NW
NW
NE
NW
NW
NW
NW
NW
SE
NW
NW
NW
Repeat of Profile 1 following partial LSL replacement
Repeat of Profile 3 following partial LSL replacement
Profiles Collected during Temporary Switch to Alternative Disinfectant (free chlorine)
15
16
17
18
4/5/2004
4/6/2004
4/6/2004
4/13/2004
NW
NW
NW
NW
Affected by switch
Affected by switch
Affected by switch
Affected by switch
Final Report, May 31, 2007
A-23
-------
Profile
No.
19
20
21
22
23
24
25
Date of
profile
4/26/2004
4/27/2004
4/29/2004
4/30/2004
5/3/2004
5/3/2004
5/7/2004
Profile
Quadrant
NW
SE
NW
NW
NW
NW
NW
Special Profile Conditions
Second repeat of Profile 3 following partial LSL replacement; Affected by switch
Repeat of Profile 1 1 ; Affected by switch
Second repeat of Profile 1 following partial LSL replacement; Affected by switch
Repeat of Profile 12; Affected by switch
Repeat of Profile 1 0; Affected by switch
Repeat of Profile 14; Affected by switch
Repeat of Profile 13; Affected by switch
Profiles Collected during Chloramination, after Temporary Switch to Alternate Disinfectant (free chlorine)
26
27
28
5/18/2004
6/28/2004
7/6/2004
NE
NW
NW
Repeat of Profile 5; Affected by switch
Second Repeat of Profile 14
Profiles Collected after Orthophosphate Addition
29
30
31
32
33
34
7/16/2004
11/30/2004
12/6/2004
1/6/2005
1/25/2005
2/22/2005
NW
NW
NW
NW
NW
NW
Second Repeat of Profile 13
Second Repeat of Profile 10
Final Report, May 31, 2007
A-24
-------
Profile
No.
35
36
37
38
39
40
41
42
43
44
45
Date of
profile
3/30/2005
4/29/2005
5/16/2005
6/1/2005
6/7/2005
7/25/2005
9/28/2005
10/5/2005
11/29/2005
12/12/2005
1/27/2006
Profile
Quadrant
NW
NW
NW
NW
NW
NW
NW
NE
NW
N
NE
Special Profile Conditions
(Notes on Profile Graphs to follow:
1. Flowing samples designated '0' or '00' and samples collected that were representative of the water main may have
measurable lead due to rapid release of lead from the lead service line to the water as it flowed through the service piping,
and/or back siphonage of water from branches of premise piping.
2. Samples designated "X" reflect water hammer conditions
3. Samples designated "25+3" for example; indicate samples collected after allowing the water to flow for 3 minutes after
the 25th liter stagnation sample was collected.
Final Report, May 31, 2007
A-25
-------
I. Profiles Collected during Chloramination
12-08-03 (Profile No. 1)
180
160
01 245 7 9 13 17 21 25 25+3 X
D Total Lead D Dissolved
12-15-03 (Profile No. 2)
180
160
140
120
2 100
40
20
0
In-house Plumbing
Lead
Service
Line
1
in
Main
012345679 11 13 13+3 X
Liter
Total Lead Dissolved Lead
Final Report, May 31, 2007.
A-26
-------
* Footnote to Profiles: Flowing samples designated '0' or '00' and samples collected that
were representative of the water main may have measurable lead due to rapid release of
lead from the lead service line to the water as it flowed through the service piping, and/or
back siphonage of water from branches of premise piping.
1-5-04 (Profile No. 3)
160 -
140 -
120 -
100 -
80 -
60 -
40 -
20 -
n -
In-house Plumbing
m
i i
i
ii
Lead Service Line
. .
Main
Ti m m m
6 8 10 12 14 16 16+3
Liter
Total Lead Dissolved Lead
Final Report, May 31, 2007.
A-27
-------
1-13-04 (Profile No. 4)
100
80
70
In-house Plumbing
LSI
Main
.a
a.
a.
50
40
30
20
10
fc
13 17 21 25 45 X 0
Liter
]Total Lead Dissolved Lead
2-9-04 (Profile No. 5)
100
In-house Plumbing
Lead Service Line
Main
70
,~ 60
Q.
Q.
^ 50
40
30
20
10
ttri
1 fh rh m m m
1245
11 13 16 19 19+3 0 X
Liter
DTotal Lead DDissolved Lead
Final Report, May 31, 2007.
A-28
-------
2/24/04 (Profile No. 6)
20
15
In-house Plumbing
Lead
Service
Line
Main
Q.
Q.
10
10 12 14 16 16+3 16+5 16+7 16+9 16+11 X 0
]Total Lead Dissolved Lead
3-2-04 (Profile No. 7)
180
160
140
120
ง. 100
Q.
In-house Plumbing
Lead Service Line
Main
40
20 --
mmm
m
12457
11 13 15 18 21 21+3 21+10 X 0
Liter
DTotal Lead DDissolved Lead
Final Report, May 31, 2007.
A-29
-------
3-9-04 (Profile No. 8)
180
160
140
120
0. 100
Q.
80
60
40
20
In-house Plumbing
Lead Service Line
Main
to
20
24 29 29+3 29+10 00
1 Total Lead Dissolved Lead
3-16-04 (Profile No. 9)
180
160
140
120
. 100
Q
D
I
40
20
0
immmmmmmmmrh
JH
1246
Detailed information was not available to
differentiate among in-house plumbing,
lead service lines, and the water main
12 15 18 21 24 27 31 35 39 39+3 39+10 X 0
Liter
DTotal Lead DDissolved Lead
Final Report, May 31, 2007.
A-30
-------
3-24-04 (Profile No. 10)
180
160
140
120
ง. 100
Q.
In-house
Plumbing
LSI
Main
40
20
mm
m
1234
10 12 14 17 20 23 26 30 0 30+3 30+10 X
1 Total Lead Dissolved Lead
180
160
140
120
ง. 100
Q.
3-24-04 (Profile No. 11)
In-house
Plumbing
Lead Service
Line
Main
n m m m m m
1 2 4 6 8 10 12 14 17 20 23 26 29 33 33+3 33+10 0 X
Liter
]Total Lead D Dissolved Lead
Final Report, May 31, 2007.
A-31
-------
3/30/04 (Profile No. 12)
120
110
100
90
80
70
60
50
40
30
20
10
fb
In-house
Plumbing
[ I
[rift
i-i
Lead
1 [L
III
Service Line
fb fb
Main
Q.
Q.
12357
10 11 13 15 18 21 24 27 0 27+3 27+10 X
Liter
1 Total Lead Dissolved Lead
3/31/04 (Profile No. 13)
180
160
140
120
ง. 100
Q.
In-house Plumbing
Lead Service Line
Main
40
20
m mm mm mm m Hi
00 1
Information was not available for
Dissolved Lead at Liter 9
4 5 7 9 11 13 15 18 21 24 27 27+3 27+10 X
Liter
DTotal Lead DDissolved Lead
Final Report, May 31, 2007.
A-32
-------
4-1-04 (Profile No. 14)
180
160
140
120
ง. 100
Q.
In-house
Plumbing
Lead Service Line
Main
40 --
20 --
1234
10 12 14 17 20 23 26 30 30+3 30+10 00 X
Liter
1 Total Lead Dissolved Lead
II. Profiles Collected during Chlorine Burn
Final Report, May 31, 2007.
A-33
-------
4-5-04 (Profile No. 15)
180
160
140
120
ง. 100
Q.
In-house Plumbing
Lead Service Line
Main
40
20
0123457
11 13 15 18 21 24 27 27+3 27+10 X
Liter
1 Total Lead Dissolved Lead
4-6-04 (Profile No. 16)
? inn
a.
a
S 80 -
n -
In -house
Plumbing
i rh
]
Lead Service Line
"
n
n
ITi m m
Main
rtartartartamrtamrtarta
PI
:
1 23457
11 13 15 18 21 24 27 0 27+3 27+10 X
Liter
DTotal Lead DDissolved Lead
Final Report, May 31, 2007.
A-34
-------
4-6-04 (Profile No. 17)
180
160
140
120
ง. 100
Q.
In -house
Plumbing
Lead Service Line
Main
40
20 --
Jk
1234
10 12 14 16 19 22 25 28 28+3 28+10 X
Liter
1 Total Lead Dissolved Lead
4-13-04 (Profile No. 18)
180
160
140
120
100
40
20
In -house
Plumbing
fta rta fta
Lead Service Line
ft
Main
rhrhrtartartarhmmrtartarta
12346
10 12 14 16 19 22 25 28 00 28 + 3 28 + X
10
Liter
DTotal Lead DDissolved Lead
Final Report, May 31, 2007.
A-35
-------
4/26/04 (Profile No. 19)
20
15
In -house Plumbing
iinj
-
Lead Service
Line
\k
m
Main
BannnriJkriaJ
Q.
Q.
10
1245
10 12 14 16 18 21 24 27 27+3 27+10 X 0
Liter
]Total Lead Dissolved Lead
4-27-04 (Profile No. 20)
160 -
140 -
120 -
ง. 100 -
a.
a
2 80-
60 -
40 -
20 -
n -
In -house
Plumbing
Lead Service
Line
n
r-m
II I m fh
i-
-,
Main
nririmrfcrhmrhrhrtartam
1 2 4
10 12 14 17 20 23 26 29 33 33+3 33+10 0 X
Liter
DTotal Lead DDissolved Lead
Final Report, May 31, 2007.
A-36
-------
4/29/04 (Profile No. 21)
100
90
70
Q.
Q.
50
40
30
20
10
In-house Plumbing
i i i i i i i i i
Lead Service Line
rm rm rm
Main
1 I~~I i i i i i i i i i i i i i i i i i i i i i
7 9 13 17 21 25 25+3 25+10 0 X
Liter
ITotal Lead Dissolved Lead
4-30-04 (Profile No. 22)
TJ
5 sn
-
In-house
Plumbing
-i n i n-1
Lead Service Line
1 l~\ I rl 1 1 i i i i
Main
r-i
1 2 3 5 7 9 10 11 13 15 18 21 24 27 27+3 27+10 0 X
Liter
D Total Lead Dissolved Lead
Final Report, May 31, 2007.
A-37
-------
5-3-04 (Profile No. 23)
In-house
Plumbing
1 2 3
Lead Service Line
I~~L
4 6 8 10
D
Main
12 14 17 20 23 26 30 30+3 30+10 0 X
Liter
Total Lead Dissolved Lead
5-3-04 (Profile No. 24)
ง. 100 -
S 80 -
In-house
Plumbing
ft rm
1 2
Lead Service Line
ft ft rb ft
Main
Ch JJ 1 1 1 a ft a
3 4 6 8 10 12 14 17 20 23 26 30 30+3 30+10 0 X
Liter
D Total Lead Dissolved Lead
Final Report, May 31, 2007.
A-38
-------
5-7-04 (Profile No. 25)
ง 100
a.
TJ
5 sn
In-house
Plumbing
n i n i m
1 2 3
Lead Service Line
\~M n \~M r* m
4 5 7 9 11
Total L
Main
i i i i i i i i i i i i m i i i i m i m i m i i i i
13 15 18 21 24 27 00 27+3 27+10 X
Liter
ead Dissolved Lead
Final Report, May 31, 2007.
A-39
-------
I. Profiles Collected during Chloramination, after Chlorine Burn
5-18-04 (Profile No. 26)
180
160
140
120
100
a.
a
2 80
40
20
In-house Plumbing
Lead Service Line
Main
fta ru rm IT!
11 13 16 19 19+3 19+10 0 X
Liter
D Total Lead Dissolved Lead
6-28-04 (Profile No. 27)
180
160
140
120
ง. 100
Q.
In-house
Plumbing
Lead Service Line
Main
40
20
El
m
1
12
17
23
30
Liter
] Total Lead Dissolved Lead
30+10 01(15)
Final Report, May 31, 2007.
A-40
-------
180
160
140
120
ง. 100
^
T3
60
40
20
7-6-04 (Profile No. 28)
In-house Plumbing
Lead Service Line
Main
h In In
00 1 2 3 5 7 9 11 13 15 18 21 24 27 27+3 27+10 X
Liter
D Total Lead D Dissolved Lead
IV. Profiles Collected after Orthophosphate Addition
Final Report, May 31, 2007.
A-41
-------
7-16-04 (ProfMe No. 29)
180
160
140
120
In-house Plumbing
fh PI rm
Lead Service Line
r* !" Fta r~ta n-i
Main
n~i m m n-i m n-i m n-i
1
a.
T3
40
20
00 1
11 13
Liter
15 18 21 24 27 27+3 27+10 X
Total Lead Dissolved Lead
11 -30-04 (Prof Me No. 30)
TJ
2 80
In-house Plumbing
~l l~l n
1234
Lead Service Line
I
I [ I
5 6 8 10 12
Li
Total Lead
Main
I h I h n-i n-i n-i n-i n-i n-i I U
14 17 20 23 26 0 26+3 26+10 X
er
Dissolved Lead
Final Report, May 31, 2007.
A-42
-------
12-6-04 (ProfMe No. 31)
In-house
Plumbing
fctll
\
Lead Service Line Main
1 2 3 4 5 7 9 11 12 13 15 17 20 23 26 00 26+3 26+10 X
Liter
] Total Lead D Dissolved Lead
1-6-05 (ProfMe No. 32)
LSL
Main
ru ru
JL
n
10 12 14 17 20 23 26 30 0 30+3 30+10 X
Liter
D Total Lead D Dissolved Lead
Final Report, May 31, 2007.
A-43
-------
1-25-05 (ProfMe No. 33)
20
18
16
14
12
10 4-
In-house Plumbing
Lead Service Line
Main
12346
10 12 14 16 18 21 24 27 27+3 27+10 0 X
Liter
] Total Lead D Dissolved Lead
2-22-05 (Profile No. 34)
In-house Plumbing
Lead Service Line
Main
mmmrhmmmm
n-i
2 3 5 7 9 11 12 13 15 17 20 23 26 26+3 26+10 X
Liter
D Total Lead D Dissolved Lead
Final Report, May 31, 2007.
A-44
-------
20
18
16
14
,~ 12
Q.
Q.
3-30-05 (Profile No. 35)
In-house Plumbing
Lead Service Line
Main
10
00 1 2 3 5 7 9
11 12 13 15 18 21 24 27 27+3 27+10 X
Liter
] Total Lead D Dissolved Lead
4-29-05 (Profile No. 36)
20
18
16
14
12
10
In-house
Plumbing
Lead Service Line
Main
a.
Q.
Eh
0124
10 12 14 15 17 20 23 26 26+3 26+10 X
Liter
D Total Lead D Dissolved Lead
Final Report, May 31, 2007.
A-45
-------
5-16-05 (ProfMe No. 37)
7 9 10 11 13 15 17 20 23 23+3 23+10 X
0 1
] Total Lead D Dissolved Lead
6-1-05 (ProfMe No. 38)
11 12 13 15 17 20 23 23+3 23+10 X
D Total Lead D Dissolved Lead
Final Report, May 31, 2007.
A-46
-------
6-7-05 (Profile No. 39)
10 11 13 15 18 21 24 24+3 24+10 X
0 1
] Total Lead D Dissolved Lead
7-25-05 (Profile No. 40)
11 13 15 17 20 23 23+3 23+10 X
Liter
D Total Lead D Dissolved Lead
Final Report, May 31, 2007.
A-47
-------
9-28-05 (ProfMe No. 41)
Lead Serivce Line
Main
00 1 245
7 9 10 11 13 15 17 20 23 23+3 23+10 X
Liter
] Total Lead D Dissolved Lead
10-5-05 (ProfMe No. 42)
120
100
In-house
Plumbing
Lead Service Line
Main
a.
Q.
11 13 15 17 20 23 23+3 23+10 X
0 1
] Total Lead D Dissolved Lead
Final Report, May 31, 2007.
A-48
-------
11-29-05 (ProfMe No. 43)
20
18
16
14
,~ 12
Q.
Q.
In-house
Plumbing
Lead Service Line
Main
Db
n
(ts
0 1 2 3 4 5 6 7 9 11 13 15 17 20 23 23+3 23+10 X
Liter
Total Lead Dissolved Lead
12-12-05 (ProfMe No. 44)
20
18
16
14
In-house
Plumbing
Lead Service Line
Main
12
SI
a.
&
T3
-------
1-27-06 (ProfMe No. 45)
1 2 3 4 5 6 7 9 11 13 15 17 20 20+3 20+10 X
Liter
] Total Lead D Dissolved Lead
1-27-06 (ProfMe No. 45)
20
18
16
14
12
10
In-house Plumbing
Lead Service Line
Main
a.
Q.
Sit
fh
0 1
7 9 11 13 15 17 20 20+3 20+10 X
Liter
] Total Lead D Dissolved Lead
Final Report, May 31, 2007.
A-50
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Appendix B
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Study Approach
The study was conducted in two steps: 1) gathering, organizing and summarizing the
available information, and listing potential causes of elevated lead levels; and 2)
evaluating and determining the most probable causes.
Step 1: Gathering, Organizing, and Summarizing Available Information
Based on data and other information provided by EPA, the contractor produced the
following:
Technical memorandum with preliminary findings and identifying additional
data needs
3-ring binder containing all reports and data gathered and reviewed
Data evaluation report
Data and information initially provided by EPA to the contractor included the following:
Studies and Reports
Caustic soda feasibility study, 1998
Electrochemical pipe loop study on lead leaching rates from lead service line (LSL)
coupons under various treatment scenarios
Sanitary survey reports for WTPs and distribution system since 1990
Microbial Comprehensive Performance Evaluation (CPE) Report for the treatment
plants
Optimum Corrosion Control Treatment (OCCT) studies and approvals (original 1993-
2000, revised 2004)
Available data from a flow-through pipe loop study looking at corrosion rates under
various treatment scenarios (study not yet started- expected completion June 2005 at
earliest)
Lead in Water Survey - 1990 materials survey estimating LSLs and other sources of
lead in the distribution system
LSL partial replacement method study - study conducted that looked at three methods
of cutting pipe and thorough flushing: homes were "profile sampled" before and for
two weeks after the partial LSL replacement work, May 2004
Treatment Related Data and Information
WTP treatment schematics and chemical dosing information
Raw and Finished Water Parameters from both WTPs
o Monthly average and maximum flow rates
o Monthly average pH
o Free and total ammonia
o Free and total chlorine
o Monthly average alkalinity as CaCOs
o Calcium
o Conductivity
o Magnesium
-------
o Temperature
o Calcium hardness, both total and dissolved
o Total coliform bacteria
o Fluoride
o Dissolved, suspended and total solids
o Bromide
o Chloride
o Sulfate
o Total Organic Carbon - raw, settled and filtered
o Metals (EPA method 200.8)
Entry Points to the Distribution System:
o Haloacetic Acid (HAAS), total and individual concentrations
o Total Trihalomethanes (TTHMs) and four individual trihalomethanes (THMs)
Distribution System Data and Information
Distribution system atlas or atlases
Total coliform (presence/absence)
LCR water quality parameter data: pH, alkalinity, calcium
HPC bacteria - limited data in terms of locations and monitoring duration
TTHM and HAAS
Nitrate and nitrite, both measured as Nitrogen
Metals
Lead first draw (LCR compliance)
Lead second draw (earlier years, this was the second liter of water; changed in 2003
to represent water sitting in the service lines)
Lead profiling data (conducted from late 2003 through August 2004) performed at
customer homes to collect every liter of water from the tap out through the water
main
Lead first and second draw customer service samples, February 2003-present.
LSL replacement samples from LSLs that were not replaced 2003-2004
Step 2: Evaluating and Determining Probable Causes
Completed Data Review
Based on additional data identified in Step 1 and then provided by EPA to the contractor,
the data review was completed.
Additional data requested by the contractor as part of step 1, and provided by EPA to the
extent it was available, included:
Data free chlorine and chloramines at entry points to the distribution system and
within the distribution system, 1994-2004 (or most current) DC WAS A dates of
periodic free chlorine use, 2001-2004 (or most current)
Additional lead profiles in DC WASA system
Inventory of partial LSL replacement, 1999-2004 (or most current)
-------
Meter specifications
Alkalinity data for distribution system entry points, 2000-2001
Source water quality data 1996-1998; 2003-2004 (or most current)
Statistical Analyses
The contractor performed various statistical analyses on water quality data to determine
correlations that could be made regarding the causes for elevated lead levels.
Evaluation of Causes
The contractor evaluated potential causes in two ways:
1. The likelihood of being a significant factor in lead release and uptake by the water
2. The magnitude of the release in relation to the lead level at the tap
For example, the uptake of lead by the water exposed to a water meter might be
significant and well documented. However, the contribution of that small segment of
water to the elevated lead at the tap might be small. Thus, in this instance, the conclusion
would be that water meters are not a significant cause of elevated lead at the tap.
Report
The contractor provided a draft report that included information and findings of both
steps 1 and 2 for EPA and peer review comments.
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Appendix C
-------
Peer Review of Elevated Lead in B.C. Drinking
Water - A Study of Potential Causative Events
July 5, 2007
Horsley Witten Group, Inc.
90 Route 6A
Sandwich, MA 02563
Prepared/or:
United States Environmental Protection Agency
Office of Ground Water and Drinking Water
-------
Peer Review Report of the Draft Study of Potential Causative Events from
Elevated Lead in B.C. Drinking Water
Contents of document:
1. Summary of peer review process and associated documentation
2. Summary table of expertise criteria and selected peer reviewers' names and
affiliations
3. Peer review charge
Appendix I: Peer Reviewer Credentials
Appendix II: Peer Reviewer Comments
Peer Review Report: Page 2
Elevated Lead in D. C. Drinking Water
-------
1. Summary of peer review process and associated documentation
The EPA study: "Elevated Lead in D.C. Drinking Water - A Study of Potential
Causative Events", documents a detection of lead in the District of Columbia Water and
Sewer Authority's (DCWASA) water delivery system. DCWASA exceeded the 15-ug/L
action level (AL) for the Lead and Copper Rule during July 2000 to June 2001 at the 90th
percentile in home tap sampling, and repeatedly exceeded the AL during subsequent
monitoring through the period ending December 2004. This study evaluates the potential
causative events and parameters contributing to the elevated lead levels in the D.C.
drinking water system.
EPA hired a contractor, Horsley Witten Group, Inc. (H&W), to facilitate a peer review of
the study in accordance with the "Peer Review Handbook", 3rd Edition, EPA 100-B-98-
001, hereinafter, "Handbook"). The peer review is intended to provide a focused,
objective evaluation of the study and causative events leading up to the contamination
incident. EPA addresses the criticisms, suggestions, and new ideas provided by the
technical reviewers prior to redrafting the reviewed work. Comprehensive, objective
technical reviews contribute to good science and regulatory acceptance of precedent-
setting methodologies and controversial issues within the scientific and regulated
communities.
H&W began the review process by reviewing the recommended list of potential
reviewers provided by EPA and selecting 3 peer reviewers to review the document. Two
of the three reviewers were selected based on their scientific or technical expertise in
issues associated with lead corrosion in distribution and plumbing systems. The third
reviewer is a representative of a drinking water utility with relevant experience.
Reviewers were screened for potential conflicts of interest, as specified in the Peer
Review Handbook. H&W queried reviewers to determine their availability to participate
in the review, and found two of the three chosen reviewers had scheduling conflicts and
could not participate. H&W found two reviewers of equal expertise, with no conflicts, to
replace the initially chosen reviewers. A revised reviewer list was developed and
forwarded to the WAM for approval on April 6, 2007.
After receiving approval of the list of reviewers, H&W emailed the reviewers one
electronic copy of the pre-decision draft document entitled "Elevated Lead in D.C.
Drinking Water - A Study of Potential Causative Events" dated February 23, 2007, along
with one electronic copy of the Peer Review Charge, instructions, and appendices. H&W
contacted reviewers periodically throughout the review period to answer any questions
reviewers had, and to determine whether reviewers would indeed be able to provide
comments by the set deadline of April 20, 2007. H&W received reviewers' comments,
compiled comments into an EPA-approved format, and submitted each comment
document to EPA.
H&W compiled and maintained a record of all potential peer reviewers, including names,
affiliations, addresses, phone numbers, qualifications, and potential conflicts of interest.
Peer Review Report: Page :
Elevated Lead in D. C. Drinking Water
-------
H&W has obtained agreements to honor confidentiality from reviewers, since the review
document is a pre-decisional draft not for general public distribution. An explanation of
such was included in both H&W's subcontract to reviewers as well as a letter of
instruction.
H&W assembled the peer review record, which consisted of: the draft work products
reviewed; the Charge; all materials provided to the reviewers; and reviewer comments.
H&W submitted the peer review record to EPA on May 3, 2007.
Information on the areas of expertise, the names, affiliations, and resumes of the selected
peer reviewers are included in this document in Appendix I.
The peer reviewers' comments are provided in Appendix II.
Peer Review Report: Page 4
Elevated Lead in D. C. Drinking Water
-------
2. Summary Table of Expertise Criteria and Selected Peer Reviewers'
Names and Affiliations
Peer Reviewers of "Elevated Lead in D.C. Drinking Water - A Study of Potential
Causative Events"
Criteria for Selecting Peer Reviewers
Scientific/technical expertise regarding lead corrosion in
distribution and plumbing systems.
Chief Operating Officer of a major drinking water utility.
Scientific/technical expertise regarding lead corrosion in
distribution and plumbing systems.
Peer Reviewer
Carol Rego,
COM
John S. Young, Jr.
American Water
JohnF. Ferguson,
Ph.D.
University of
Washington
Peer Review Report:
Elevated Lead in D. C. Drinking Water
Page 5
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3. Peer Review Charge
Elevated Lead in D.C. Drinking Water - A Study of Potential Causative Events
Background
In 2004, EPA convened a series of expert workshops in light of concerns raised about the
effectiveness of the Lead and Copper Rule (LCR). The recommendations from these
workshops led EPA to consider several actions, which included short-term and long-term
revisions to the LCR, additional expert workshops, new and expanded guidance, and
additional research. In terms of additional research, EPA identified a need to perform an
in-depth analysis to document and determine to the extent possible the cause or causes of
elevated lead levels in the District of Columbia (D.C.) drinking water.
Immediately prior to 2000, D.C. drinking water did not typically show lead levels that
exceeded the LCR action level of 0.015 mg/L. On November 1, 2000, the Washington
Aqueduct, which operates the Dalecarlia and McMillan Water Treatment Plants, switched
from free chlorine to chloramine disinfection. Since early 2001, the D.C. Water and
Sewer Authority (DCWASA) reported some elevated lead levels in drinking water
samples from D.C. residents' taps.
This study documents and evaluates the potential causative events and parameters
contributing to the high levels of lead in D.C. drinking water. Section 1 provides a
summary of the document, including background information. Sections 2, 3, and 4
provide background information on the lead monitoring program, water treatment
facilities, and distribution system conditions. Section 5 discusses the following causative
factors along with the likelihood of each contributing to the situation:
1. Lead release from piping systems
2. Conversion from free chlorine to chloramines for final disinfection
3. Water quality parameters in the distribution system
4. Other lead-bearing materials
5. Galvanic corrosion of lead service lines
6. Effect of grounding currents on lead-bearing components
7. City-wide meter replacement program
8. Drought conditions and effects on corrosivity of DCWASA water
Peer Review Report: Page 6
Elevated Lead in D. C. Drinking Water
-------
The study concludes that (1) the primary source of lead release was attributed to the
presence of lead service lines (LSLs) in the DCWASA distribution system, and (2) the
major causative factor of high lead levels at the consumers' taps was likely the change in
oxidation state (as indicated by ORP) resulting from the conversion from free chlorine to
chloramines. The relatively high concentration of free chlorine that was used for residual
disinfection prior to the conversion to chloramines likely facilitated the formation of
Pb (IV) species in the DCWASA distribution system. Additional contributing factors were
likely related to low operating pH levels and pH variations in the distribution system
which, based on conventional understanding of Pb (II) solubility per the LCR, would lead
to greater Pb (II) release. Faucets, solder, and other home plumbing components likely
contributed, but were not the major source of lead release to DCWASA tap samples.
Please find attached a copy of the draft study and appendices for your review. This
version of the report reflects Agency comments received on an earlier draft. We expect
that this version of the report, with some additional minor modifications, will be the final
version. Your comments will be useful in preparing the final version of the report and
discussing the findings of the study with the public.
To assist in your review of the study, we ask that you pay particular attention to the
following questions:
a. Does the study consider potential causative events that are appropriate? Are the
causative events and factors considered all relevant to the purpose of the study?
What additional causative events or factors, if any, should be considered?
b. Does the study consider each causative event adequately? Is the data presented
all relevant to the purpose of the study?
c. Do the data and analyses support the conclusions? Are there additional analyses
that could better support the conclusions? What additional conclusions, if any,
can be reached based on the data and analyses?
d. Section 6 of the study identifies possible follow-on work based on available
findings and conclusions drawn from the study. Which, if any, of the
recommended follow-on work should EPA undertake? What additional follow-on
work and/or research should EPA undertake as a result of this study?
Peer Review Report: Page 7
Elevated Lead in D. C. Drinking Water
-------
Appendix I: Peer Reviewer Credentials
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General Biographical Information 5/2005
JOHN F. FERGUSON
Professor of Civil Engineering
University of Washington
304 More Hall, Box 352700
Seattle, WA 98195-2700
(206)543-5176
(206) 543-1543 Fax
jferg@u.washington.edu
Academic Background
Ph.D. Stanford University 1970
M.S.C.E. Stanford University 1964
B.S.C.E (with honors) Stanford University 1963
Professional History
Professor, Department of Civil Engineering, University of Washington, Seattle, WA, 1979-
present; Chair 1992-1997; Associate Chair 1987-1992; Acting Chair 1986-1987; Environmental
Engineering and Science Program Director 1983-1987.
Visiting Scientist, Norwegian Water Research Institute, Oslo, 1979-80.
Associate Professor, Department of Civil Engineering, University of Washington, Seattle, WA,
1974-1979.
Assistant Professor, Department of Geography and Environmental Engineering, The Johns
Hopkins University, Baltimore, MD, 1970-1974.
Research Fellow, Division of Engineering and Applied Physics, Harvard University, Cambridge,
MA, 1969-1970.
Research Engineer, Los Angeles County Sanitation Districts, Lancaster, CA, 1964-1966
Refereed Journal Publications
Ferguson, J.F. and P.L. McCarty (1971) Effects of carbonate and magnesium on calcium
phosphate precipitation, Environ. Sci. Technol, Vol. 5, 434-540.
Jenkins, D., J.F. Ferguson, and A.B. Menar (1971) Chemical processes for phosphate removal,
Water Res., Vol. 5, 369-389.
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Ferguson, J.F. and J. Gavis (1972) A review of the arsenic cycle in natural waters, Water Res.,
Vol. 6, 1259-1274.
Gavis, J. and J.F. Ferguson (1972) The cycling of mercury through the environment, Water Res.,
Vol. 6, 989-1008.
Ferguson, J.F., DJ. Jenkins, and J. Eastman (1973) Calcium phosphate precipitation at slightly
alkaline pH values, Jour. Water Pollution Control Fed, Vol. 45, 620-631.
Gavis, J. and J.F. Ferguson (1975) Kinetics of carbon dioxide uptake by phytoplankton at high pH,
Limnol. Ocean. Vol. 20, 211-221.
Anderson, M.A., J.F. Ferguson, and J. Gavis (1976) Arsenate adsorption on amorphous aluminum
hydroxide,/. Colloid Interface Science, Vol. 54, 391-399.
Ferguson, J.F. and T.A. King (1977) A model for phosphate removal with aluminum addition,
Jour. Water Pollution Control Fed., Vol. 49, 646-658.
Ferguson, J.F., G.F.P. Keay, M.S. Merrill, and A. Benedict (1979) Powdered activated carbon
contact stabilization in activated sludge, JWPCF, Vol. 51, 2314-2323.
Eastman, J.A. and J.F. Ferguson (1981) Solubilization of particulate organic carbon during the
acid phase of anaerobic digestion, JWPCF, Vol. 53, 352-366.
Benjamin, M.M., J.F. Ferguson, and M.E. Buggins (1981) Treatment of sulfite evaporator
condensate with an anaerobic reactor, TAPPI, Vol. 65, 96-101.
Asplund, R., B.W. Mar, and J.F. Ferguson (1982) Total suspended solids in highway runoff in
Washington State, ASCE, JEED, Vol. 108, 391-404.
Herrera, C.F., J.F. Ferguson, and M.M. Benjamin (1982) Evaluation of the potential for
contamination of drinking water from the corrosion of tin/antimony solder, JAWWA, Vol. 74, 368-
376.
Ferguson, J.F., B.J. Eis, and M.M. Benjamin (1983). The fate and effect of bisulfite in anaerobic
treatment, JWPCF, Vol. 55, 1355-1365.
Benjamin, M.M., S.L. Woods, and J.F. Ferguson (1984) Toxicity and biodegradability of pulp mill
waste constituents exposed to anaerobic bacteria, Wat. Res., Vol. 18, 601-607.
Ferguson, J.F., B.J. Eis, and M.M. Benjamin (1984) Neutralization in anaerobic treatment of an
acidic waste, Wat. Res., Vol. 18, 573.
Hendrickson, K.J., M.M. Benjamin, and J.F. Ferguson (1984) Removal of silver and mercury from
spent COD test solutions, JWPCF, Vol. 56, 468-473.
Ferguson, J.F. and L. Vrale (1984) Chemical aspects of the lime seawater process, JWPCF, Vol.
56,355-363.
Nitchals, D.R., M.M. Benjamin, and J.F. Ferguson (1985) Anaerobic treatment of caustic
extraction waste with sulfite evaporator condensate, JWPCF, Vol. 57. 253-262.
Reiber, S.H., J.F. Ferguson, and M.M. Benjamin (1987) Corrosion monitoring and control in the
Pacific Northwest, Jour. Am. Wat. Works Assoc., Vol. 79, No. 2, 71-74.
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Stone, A., D. Spyridakis, M.Benjamin, J. Ferguson, J. Richey, and S. Osterhus (1987) The effects
of short-term changes in water quality on copper and zinc corrosion rates, Jour. Am. Wat. Works
Assoc., Vol. 79, No. 2, 75-82.
Schultz, M., M.M. Benjamin, and J.F. Ferguson (1987) Adsorption and desorption of metals on
ferrihydrite, Environ. Sci. Technol, Vol. 21, 863-869.
Woods, S.L., J.F. Ferguson, and M.M. Benjamin (1988) Characterization of chlorophenol and
chloromethoxybenzene biodegradation during anaerobic treatment, Environ. Sci. Technol., Vol.
23, 62-68.
Reiber, S., J.F. Ferguson, and M.M. Benjamin (1988) An improved method for corrosion rate
measurement by weight loss, J. Am. Water Works Assoc., Vol. 80, No. 11, 41-46.
Nordqvist, K.R., M.M. Benjamin, and J.F. Ferguson (1988) Effects of cyanide and polyphosphates
on adsorption of metals from simulated and real metal plating wastes, Water Research, Vol. 22,
837-846.
Puhakka, J.A., J.F. Ferguson, M.M. Benjamin, M. Salkinoja-Salonen (1989) Sulfur reduction and
inhibition in anaerobic treatment of simulated pulp mill wastewater, Systematic and Applied
Microbiology, Vol 11, 202-206.
Puhakka, J.A., M.M. Benjamin, J.F. Ferguson, and M. Salkinoja-Salonen (1990) Effect of
molybdate ions on methanation of simulated and natural wastewater, Appl. Microbiol. Biotechnol,
Vol. 32, 494-498.
Puhakka, J.A., M. Salkinoja-Salonen, J.F. Ferguson, and M.M. Benjamin (1990) Carbon flow in
acetoclastic enrichment cultures from pulp mill effluent treatment, Water Research, Vol 24, 505-
519.
Paulson, A.J., M.M. Benjamin, and J.F. Ferguson (1990) Zn solubility in low carbonate solution,
Water Research, Vol. 23, 1563-1569.
Banerjee, S., J.J. Horng, J.F. Ferguson (1991) Field Experience with Electrokinetics at a
Superfund Site, Transporation Research Record, 1312, 167-174
Labib, F., J.F. Ferguson, M.M. Benjamin, M. Merigh, and N.L. Ricker (1992) Anaerobic butyrate
degradation in a fluidized bed reactor: The effects of increased concentrations of H2 and acetate,
Environ. Sci. Technol, Vol. 26, 369-376.
Wang, S-H., J.F. Ferguson, and J.L. McCarthy (1992) The decolorization and dechlorination of
kraft bleach plant effluent solutes by use of three fungi: Ganaderma lacidum, Coriolus versicolor
andHericium erinaceum, Holzforschung, Vol. 46, 219-223.
Labib, F., J.F. Ferguson, M.M. Benjamin, M. Merigh, N.L., and N.L. Ricker (1993) Mathematical
modeling of an anaerobic butyrate degrading consortia: Predicting their response to organic
overloads, Environ. Sci. Technol., Vol. 27, No. 13, 1673-2884.
Edwards, M. and J.F. Ferguson (1993) Accelerated testing of copper corrosion, J. Amer. Water
Works Assoc., Vol. 85, No. 10, 105-113.
Long, J.L., H.D. Stensel, J.F. Ferguson, S.E. Strand, J.E. Ongerth (1993) Anaerobic and aerobic
treatment of chlorinated aliphatic compounds, Jour. Environ. Engineering, Vol 119, 303-320.
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Makinen, P.M., TJ. Theno, J.F. Ferguson, I.E. Ongerth, and J.A. Puhakka (1993) Chlorophenol
toxicity removal and monitoring in aerobic treatment recovery from process upsets, Environ. Sci.
Technol., Vol 27, 1434-1439.
Wang, S.-H., J.L. McCarthy, and J.F. Ferguson (1993) Utilization of glucososaccharinic acid and
components of kraft black liquor as energy sources for growth of anaerobic bacteria,
Holzforschung, Vol. 47, 141-148.
Perkins, P.S., S.J. Komisar, J.A. Puhakka, and J.F. Ferguson (1994) Effects of electron donors and
metabolic inhibitors on reductive dechlorination of 2,4,6-trichlorophenol, Water Research., Vol.
28, No. 10,2101-2107.
Ryding, J.M., J.A. Puhakka, J.F. Ferguson, and S.E. Strand (1994) Degradation of chlorinated
phenols by a toluene enriched microbiol culture, Water Research, Vol 28, No. 9, 1897-1906.
Ofjord, G.D., J.A. Puhakka, and J.F. Ferguson (1994) Reductive dechlorination of Aroclor 1254
by marine sediment cultures, Environ. Sci. Technol., Vol 25, No. 13, 2286-2294.
Edwards, M., J.F. Ferguson, and S.H. Reiber (1994) The pitting corrosion of copper, JAWWA,
Vol. 86, No. 7, 74-90.
Puhakka, J.A., R.P. Herwig, P.M. Koro, G.V. Wolfe, and J.F. Ferguson (1995) Biodegradation of
chlorophenols by mixed and pure cultures from a fluidized-bed reactor, Appl. Microbiol.
Biotechnol.,Vo\. 42, 951-957.
Sletten, R.S., M.M. Benjamin, J.J. Horng, and J.F. Ferguson (1995) Physical-chemical treatment
of landfill leachate for metals removal, Water Research., Vol. 29, No. 10, 2376-2386.
Porter, R.L. and J.F. Ferguson (1995) Improved monitoring of corrosion processes, JAWWA, Vol.
87, No. 11,85-95.
Mannisto, M.K., E.S. Melin, J.A. Puhakka, and J.F. Ferguson (1996) Biodegradation of PAH
mixtures by a marine sediment enrichment, Jour. Poly cyclic Aromatic Hydrocarbons, Vol. 11, 27-
34.
Chen, C., J.A. Puhakka, and J.F. Ferguson (1996) Transformation of 1,1,2,2-tetrachloroethane
under methanogenic conditions, Environ. Sci. Technol, Vol. 30, No. 2, 542-547.
Korshin, G.V., S.A.L. Perry, M.A. Edwards, and J.F. Ferguson (1996) The influence of natural
organic matter on corrosion of copper in potable water, JAWWA, Vol. 88, No. 7, 36-47.
Melin, E.S., J.A. Puhakka, S.E. Strand, K.J. Rockne, and J.F. Ferguson (1996) Fluidized-bed
enrichment of marine ammonia-to-nitrite oxidizer and their ability to cometabolically oxidize
chloroaliphatics, Int. Biodet. Biodegrad..,Vo\ 38, No. 1, 9-18.
Melin, E.S., J.F. Ferguson, J.A. Puhakka, (1997) Pentachlorophenol biodegradation kinetics of an
oligotrophic fluidized-bed enrichment culture, Appl. Microbiol. Biotechnol. 47, 675.
Ballapragada, B.S., H.D. Stensel, J.A. Puhakka, J.F. Ferguson (1997) Effect of hydrogen on
reductive dechlorination of chlorinated ethenes, Environ. Sci. Technol. 31, 1728-1734.
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Melin, E.S., J.A. Puhakka, J.F. Ferguson, (1998) Enrichment and operation strategies for
polychlorophenol degrading microbial cultures in an aerobic fluidized-bed reactor, Wat. Environ.
Res., 70(2), 171-180.
Ward, A., H.D. Stensel, J.F. Ferguson, G. Ma, S. Hummel (1998) Effect of autothermal treatment
on anaerobic digestion in the dual digestion process. Wat. Sci. Tech. 38, 435-442
Mohn, H., J.A. Puhakka, J.F. Ferguson (1999) Effects of electron donors on degradation of
pentachlorophenol in a methanogenic fluidized bed reactor. Environmental Technology, 20:909-
920.
Zou, S., K.M. Anders, J.F. Ferguson (1999) Pentachlorophenol dechlorination in fluidized bed
reactors under methanogenic conditions. Bioremediation Journal, 3(2): 93-104
Korshin, G.V., J.F. Ferguson, A.N. Lancaster (1999) Influence of natural organic matter on the
corrosion of leaded brass in potable water. Corrosion Science, 42(1), 53-62.
Magar, V.S., H.D. Stensel, J.A. Puhakka, J.F. Ferguson (1999) Sequential anaerobic
dechlorination of pentachlorophenol: Competitive inhibition effects and a kinetic model.
Environ. Sci. Technol. 33, 1604-1611.
Chen, C., B.S. Ballapragada, J.A. Puhakka, S.E. Strand, and J.F. Ferguson (1999) Anaerobic
transformation of 1,1,1-trichloroethane by municipal digester sludge. Biodegradation, 10, 297-
305.
Zou, S., K.M. Anders, J.F. Ferguson (2000) Biostimulation and bioaugmentation of anaerobic
pentachlorophenol degradation in contaminated soils. Bioremediation Journal, 4(1), 19-25.
Ferguson, J.F. and J.M.H. Pietari, (2000) Anaerobic transformations and bioremediation of
chlorinated solvents, Environmental Pollution, 107, 209-215 .
Zou, S., H.D. Stensel, J.F. Ferguson (2000) Carbon tetrachloride degradation: Effect of microbial
growth substrate and vitamin 812 content. Environ. Sci. Technol. 34(9), 1751-1757.
Magar, V.S., H.D. Stensel, J. Puhakka, J.F. Ferguson (2000) Characterization studies of an
anaerobic, pentachlorophenol-dechlorinating enrichment culture. Bioremediation Journal, 4(4),
285-293.
Moen, G., H.D. Stensel, R. Lepisto, J.F. Ferguson (2003) Effects of solids retention time on the
performance of thermophilic and mesophilic digestion of combined municipal wastewater sludges,
Water Environment Research, 75(6), 539-548.
Korshin, G.V., J.F. Ferguson, A.N. Lancaster (2005) Influence of natural organic matter on the
morphology of corroding surfaces of lead surfaces and behavior of lead-containing particles,
Water Research, 39,811-818.
Pietari, J.M.H., Herwig, R.P. and J.F. Ferguson, Characterization of a psychrotrophic, anaerobic
tetrachloroethene and trichloroethene dechlorinating enrichment, submitted to Environ. Sci.
Technol.
Pietari, J.M.H., Herwig, R.P. and J.F. Ferguson, Isolation and characterization of a PCE to cDCE
dechlorinating strain JPD-1, manuscript in preparation (pending replication of DNA sequencing).
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Conklin, A.S., Bucher, R.H., Stensel, H.D. and J.F. Ferguson, Oxygen inhibition and toxicity in
anaerobic sludge digestion, submitted Water Environ. Research.
Conklin, A, Stensel, HD, and JF Ferguson (2005) The growth kinetics and competition between
Methanosarcina and Methanosaeta in mesophilic anaerobic digestion, submitted Water Environ.
Research.
Fully-Refereed Conference Proceedings
Ferguson, J.F and R..L. Horres (1979) Two-step precipitation of calcium phosphates, Progress
Water Technology, Suppl. 1, 157-170.
Damhaug, T., J.F. Ferguson, H. Buset, and R. Brusletto (1981) Control of alum addition in
wastewater treatment, Wat. Sci. Tech., Munich, 531-537.
Brown, C.A., K.E. Kiernan, J.F. Ferguson, and M.M. Benjamin (1984) Treatability of recreational
vehicle wastewater in septic systems at highway rest areas, Transportation Research Record, Vol
995, 1-11.
Hakulinen, R., S. Woods, J.F. Ferguson, and M.M. Benjamin (1985) The role of facultative
anaerobic microorganisms in anaerobic biodegradation of chlorophenols, Wat. Sci. Tech., Vol. 17,
289-301.
Ferguson, J.F. and M.M. Benjamin (1985) Studies of anaerobic treatment of sulfite process
wastes, Wat. Sci. Tech., Vol. 17, 113-121.
Qiu, R., J.F. Ferguson, and M.M. Benjamin (1987) Sequential anaerobic and aerobic treatment of
Kraft pulping wastes, Wat. Sci. Tech. 19,
Ferguson, J.F. and E. (Jonsson) Dalentoft (1991) Investigation of anaerobic removal and
degradation of organic chlorine from Kraft bleaching wastewaters, Wat. Sci. Tech., Vol 24, 241-
250
Rasmussen, G., S.J. Komisar, J.F. Ferguson, (1992) Transformation of Tetrachloroethane to
Ethene in Mixed Methanogenic Cultures: Effect of Electron Donor, Biomass Levels, and
Inhibition, in Bioremediation of Chlorinated and Poly cyclic Aromatic Hydrocarbon
Compounds, R.E. Hinchee, et al., eds. Lewis Publishers, p. 309-313.
Puhakka, J.A., P.M. Makinen, M. Lundin, and J.F. Ferguson (1993) Aerobic and anaerobic
biotransformation and treatment of chlorinated pulp bleach waste constituents, Wat. Sci. Tech.,
Vol. 29, No. 5-6, 73-80.
Ferguson, J.F. (1994) Anaerobic and aerobic treatment for AOX removal, Wat. Sci, Tech., Vol. 29,
No. 5-6, H49-162.
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Melin, E.S., J.A. Puhakka, M. Mannisto, and J.F. Ferguson (1995) Degradation of polycyclic
aromatic hydrocarbons by a marine fluidized-bed enrichment, in Biological Unit Processes for
Hazardous Waste Treatment, Vol. 9 of Proceedings of 3rd International Symposium on In Situ
and On-Site Bioreclamation, Hinchee, Skeen and Sayles, eds., Battelle Press, Columbus, OH, 325-
330.
Magar, V.S., H. Mohn, J.A. Puhakka, H.D. Stensel, and J.F. Ferguson (1995) Reductive
dechlorination of pentachlorophenol by enrichments from municipal digester sludge, in
Bioremediation of Chlorinated Solvents, Vol. 4 of Proceedings of3rd International Symposium
on In Situ and On-Site Bioreclamation, Hinchee, Leeson and Semprini, eds., Battelle Press,
Columbus, OH, 77-83.
Ballapragada, B.S., J.A. Puhakka, H.D. Stensel, and J.F. Ferguson (1995) Development of
tetrachloroethene transforming anaerobic cultures from municipal digester sludge, in
Bioremediation of Chlorinated Solvents, Vol. 4 of Proceedings of 3rd International symposium
on In Situ and On-Site Bioreclamation, Hinchee, Leeson and Semprine, eds, Battelle Press,
Columbus, OH.
Puhakka, J.A., E.S. Melin, K.T. Jarvinen, P.M. Koro, J.A. Rintala, P. Makinen, W.K. Shieh, and
J.F. Ferguson (1995) Fluidized-bed biofilms for chlorophenol mineralization, Wat. Sci. Tech..,
Vol. 31, No. 1,227-235.
Korshin, G.V., J.F. Ferguson, A. Lancaster, H. Wu (1997) Influence of Humic Substances on the
Corrosion of Copper- and Lead-Containing Materials in Potable Water, in The Role of Humic
Substances in the Ecosystems and in Environmental Protection, Drozd, Gonet, Senesi, Weber,
eds., International Humic Substances Society, Wroclaw, Poland.
A. S. Conklin, J. D. Zahller, R. H. Bucher, H. D. Stensel and J. F. Ferguson (2004)
Acetoclastic and Hydrolytic Activity in Anaerobic Digestion - Keys to Process Stability,
Anaerobic Digestion 2004, 10th World Congress, Montreal, August.
A. J. Straub, A. C. Conklin, J. F. Ferguson, H. D. Stensel (2005) Use of the ADM1 to investigate
the effects on mesophilic digester stability of acetoclastic methanogens population dynamics.
The First International Workshop on the IWA Anaerobic Digestion Model No. 1, 4-6 September
2005, Lyngby, Denmark
Abstract and Non-Refereed Conference Proceedings and Other Non-Journal Articles
(incomplete listing)
Ferguson, J.F., D. Jenkins, and W. Stumm (1971) Calcium phosphate precipitation in wastewater
treatment, mWater 1970 Chem. Engr. Prog. Symposium Series, Vol. 67, 107.
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Ferguson, J.F. and D. Simmons (1975) The fate of nitrogen and phosphorus in Back River sub-
estuary, in Waste Treatment Studies, Chesapeake Research Consortium, Baltimore.
Gavis, J.W. Pasciak, and J.F. Ferguson (1975) Diffusion transport and kinetics of nutrient uptake
by phytoplankton, (abstract), ACS National Meeting.
Ferguson, J.F. and D.N. Given (1976) Chemical precipitation in water softening and iron and
manganese removal, Proceedings, 18th Annual Public Water Supply Engineers' Conference,
University of Illinois, 5-24.
Ferguson, J.F., G.F.P. Keay, M.S. Merrill, and A.H. Benedict (1976) Powdered activated carbon-
biological treatment: Low detention time process, Proceedings 31st Purdue Industrial Waste
Conference, 468-478.
Spencer, R., A. J. Shuckrow, and J.F. Ferguson (1976) The addition of powdered activated carbon
to anaerobic digesters effects on methane production, Extended Abstracts for ASCE-EED National
Meeting, Seattle.
Woods, S.L., J.F. Ferguson, and M.M. Benjamin (1981) Assessing the toxicity of sulfite
evaporator condensate to methanogens, Proceedings ASCE Water Forum-81, San Francisco.
Ferguson, J.F. (1985) Anaerobic treatment of pulping and bleaching waste streams, Proc. AICHE
1985 National Meeting, presented August, 1985, Seattle, WA.
Jurgensen, S.L., M.M. Benjamin, and J.F. Ferguson (1985) Treatability of therm omechanical
pulping process effluent with anaerobic biological reactors, Proc. 1985 TAP PI Environmental
Conference, presented April, 1985, Mobile, AL.
Ferguson, J.F. (1986) Plumbing materials and water quality deterioration in Water Quality
Concerns in the Distribution System, AWWA Proceedings, Denver, CO.
Labib, F., J.F. Ferguson, and M.M. Benjamin (1988) The response of a butyrate fed anaerobic
fluidized bed reactor to transient loading, Proc. 43r Purdue Industrial Waste Conference, Lewis
Publishers, 363-371.
Ferguson, J.F., Luonsi, A., and D. Ritter (1990) Sequential anaerobic/aerobic biological treatment
of bleaching wastewaters, Proc. TAPPIEnvironmental Conference, Seattle, April, 1990,333-338.
Rumpf, M. I. and J.F. Ferguson (1990) Anaerobic pretreatment of a landfill leachate for metals
and organics removal, Proc. 1990 ASCEEnvir. Engr. Specialty Conference, Washington, D.C.,
552-559.
Leif, W., J.F. Ferguson, and M.M. Benjamin (1990) Assessing the corrosion of lead tin solder
(abstract), AWWA Water Quality Technology Conference., San Diego, November.
Hodges, L.M., S.J. Komisar, H.D. Stensel, J.F. Ferguson (1990) Volatile organic degradation in
fermentation reactors. Proc. 63rd Annual Conference of the Water Pollution Control Federation,
Wash. D.C.
Ferguson, J.F., E. Tuomi, and H.D. Stensel (1991) Advanced biological treatment for groundwater
contaminants: Development of specialized aerobic consortia, Proceedings Paper, Air and Waste
Management Association, Vancouver.
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LaFond, R.A. and J.F. Ferguson (1991) Anaerobic and aerobic biological processes for removal of
chlorinated organics from Kraft bleaching wastes, Proc. TAP PI Environmental Conference, San
Antonio, 797-805.
Ferguson, J.F. (1993) Anaerobic and aerobic treatment for AOX removal, Proc. TAPPI-1993
Environmental Conference, 857-864.
Ferguson, J.F., G.V. Korshin, S.A.L. Perry, and B. Paris, (1993) Evaluation of water quality
effects on corrosion of copper and lead-tin solder in Portland water, Proc. 1993 Water Quality
Technology Conference,AWWA, Miami, FL, 1481-1499.
Ofjord, G.D., J. Lee, JA. Puhakka, R.P. Herwig, and J.F. Ferguson (1993) Dechlorination of
Pentachlorophenol and poly chlorinated biphenyls by marine sediment enrichments, Proc. IAWAQ
Specialized Conference on Aquatic Sediments, Milwaukee, WI.
Ballapragada, B.S., V.S. Magar, J.A. Puhakka, H.D. Stensel, and J.F. Ferguson (1994) Fate and
biotransformation of tetrachloroethene and pentachlorophenol in anaerobic digesters, Proc. 1994
Wat. Environ. Fed. Annual Conference, Chicago.
Korshin, G.V. and J. F. Ferguson (1996) Effects of natural organic matter on corrosion of copper
and lead-containing brass in potable waters, Proc. Intl. Workshop on Internal Corrosion in Water
Distribution Systems, Gothenburg, Sweden.
Hinck, M.L., J.A. Puhakka, J.F. Ferguson (1996) Resistance of EDTA and DTPA to Aerobic and
Anaerobic Biodegradation, Proc. 5f IAWQ Symposium on Forest Industry Wastewaters,
Vancouver, B.C.
Ferguson, J.F., S.H. Reiber, G.V. Korshin, R.L. Porter, and M.A. Edwards (1996) Development in
pipe coupon monitoring techniques for corrosion control studies, Proc. Intl. Workshop on Internal
Corrosion in Water Distribution Systems, Gothenburg, Sweden.
Boyle, M.F., B.S. Ballapragada, H.D. Stensel, J.F. Ferguson (1997) Chloroethene dechlorination
kinetics of enrichments developed under different loading conditions, Proc. Fourth Int 'I In Situ
and On-Site Bioremediation Symposium, New Orleans.
Zou, S, K.M. Anders, J.F. Ferguson (1997) Biostimulation and bioaugmentation of anaerobic
pentachlorophenol degradation, Proc. Fourth Int 'I In Situ and On-Site Bioremediation
Symposium., New Orleans.
Korshin, G.V., J.F. Ferguson (1997) Effects of Ozonation and Chlorination of NOM on Corrosion
of Lead and Copper. AWWA Annual Conference, Atlanta.
Ward, A, H.D. Stensel, J.F. Ferguson, G. Ma, S. Hummel (1997) Preventing growth of pathogens
in post-pasteurized biosolids, Proc. WEF Annual Conf., Chicago.
Maco, R. S., H.D. Stensel, J.F. Ferguson (1998) Impacts of solids recycling strategies on
anaerobic digester performance, Proc. WEF Annual Conf., Orlando FL, [Vol. 2, pp. 213-230]
Zou, S., H.D. Stensel, J.F. Ferguson (1998) Biological treatment of carbon tetrachloride in soil
vapor extraction contaminated gases, Vol. 2 of Proceedings of the International Conference on
Decommissioning and Decontamination and on Nuclear and Hazardous Waste Management,
American Nuclear Society, Denver, CO. pp 1045-1050.
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Pietari, J.M.H., J.F. Ferguson (1999) Characterization of a psychrophilic TCE-dechlorinating
culture and comparison with a mesophilic dechlorinating culture. In Situ and On-Site
Bioremediation Symposium, San Diego, April.
Pietari, J.M.H., R.P. Herwig, J.L. McLarnan, J.F. Ferguson (1999) Characterization of an
anaerobic PCE or TCE to cis-l,2-DCE dechlorinating psychrotrophic enrichment. American Soc.
Microbiol. Annual Meeting, Chicago, May.
Ferguson, J.F., G.V. Korshin (1999) Effects of humic substances on drinking water quality. Proc.
4th Finnish Conference of Environ. Sciences, Tampere, Finland. May
Elardo, P., Danowski, P., J. Ferguson (1999) Options for treating stormwater runoff from wood-
preserving facilities, Industrial Wastewater, Nov/Dec 1999, pp 34-39.
Bucher, B., G. Newman, R. Moore, R. Lepisto, H.D. Stensel, J.F. Ferguson (2001) Pilot Plant
Investigation of Thermophilic-Mesophilic Digestion for a Full-Scale Retrofit, Biosolids 2001,
Proceedings Joint WEF/AWWA Biosolids and Plant Residuals Conference, San Diego, February
(13)
Moen, G., Stensel, H.D., Lepisto, R., J.F. Ferguson (2001) Effect of Solids Retention Time on the
Performance of Thermophilic and Mesophilic Digestion, WEFTEC, October.
J.M.H. Pietari, R.P. Herwig, J.F. Ferguson (2001) Characterization of tetrachloroethene and cis-
1,2-dichloroethene dechlorinating cultures with terminal restriction fragment length
polymorphism (T-RFLP) analysis, In situ and On-site Biormediation, 6th International
Symposium, San Diego. June.
J.M.H. Pietari, R.P. Herwig, J.F. Ferguson (2002) Characterization of a microaerophilic and
psychrotrophic, tetrachloroethene to cis-l,2-dichloroethene dechlorinating bacterium, Strain JPD-
1, American Society of Microbiology National Meeting, Salt Lake City, UT, May.
Satterberg, J.M., Herwig, R.P., and J.F. Ferguson (2003) Dehalogenation of tetrachlorethylene in
estuarine sediment enrichments: characterization of the dechlorinating microbial community and
effect of sulfate reduction inhibition. NIEHS Superfund Basic Research Program Annual
Meeting, Dartmouth, NH, November
Conklin, A.S., Bucher, R.H., Stensel, H.D. and J.F. Ferguson (2004) Oxygen inhibition and
toxicity in anaerobic sludge digestion, Water Environment Federation Biosolids Specialty
Conference, Salt Lake City, UT, February.
Conklin, A.S., Zahller, J.D., Bucher, R.H., Stensel, H.D., and J.F. Ferguson (2004) Acetoclastic
and hydrolytic activity in anaerobic digestionkeys to process stability, Anaerobic Digestion
2004, International Water Association Specialty Conference, Montreal, Quebec, August. (Vol. 2,
pp 833-838).
10
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Bouwman, R., Langwaldt, J.H., J.F. Ferguson, R. Lepisto (2004) Toxicity and biodegradation of
long chain fatty acids in thermophilic anaerobic sludge, Anaerobic Digestion 2004, International
Water Association Specialty Conference, Montreal, Quebec, August.
Bucher, RH, Zahller, JD, Conklin, AS, Ferguson, JF and HD Stensel (2004) Evaluation and
Modeling of Staged Anaerobic Digestion, Anaerobic Digestion 2004, International Water
Association Specialty Conference, Montreal, Quebec, August
Conklin, A., Stensel, HD, and JF Ferguson, The growth kinetics and competition between
Methanosarcina and Methanosaeta in mesophilic anaerobic digestion, accepted for presentation at
WEFTEC, October 2005, Washington DC
Conklin, A, Zahller, J, Stensel, HD, and JF Ferguson, Development of a tool to monitor anaerobic
digester stability and capacity and its application to full-scale digesters, accepted for presentation
at WEFTEC, October 2005, Washington DC
Books, Chapters
Jenkins, D., V. Snoeyink, J.F. Ferguson, and J. Leckie (1971) Water Chemistry Laboratory
Manual, Assoc. of Environmental Engineering Professors, 1971 (revised 1973, 1980), publisher in
1980 John Wiley and Sons.
Jenkins, D., A.B. Menar, and J.F. Ferguson (1973) Recent studies of calcium phosphate-
precipitation in wastewaters, in Applications of New Concepts of Physical-Chemical
Wastewater Treatment, Progress in Water Technology, Vol. 1, Pergamon Press.
Ferguson, J.F. and M.A. Anderson (1974) Chemical forms of arsenic in water supplies and their
removal, in Chemistry of Water Supply, Treatment and Distribution, Vol. 1, A. Rubin, ed.
Ann Arbor Science Publishers, Ann Arbor.
Ferguson, J.F. (1975) Chemical precipitation modeling in sanitary engineering, in Mathematical
Modeling for Water Pollution Control Processes, T.M. Keinath and M.P. Wanielista, eds., Ann
Arbor Science Publishers, Ann Arbor.
Ferguson, J.F. (1985) Corrosion arising from low alkalinity, low hardness or high neutral salt
content water, Chapter 8 in EBI/AWWARF Project Book, June, 1985.
Ferguson, J.F., O. Von Franque, and M.R. Schock (1996) Corrosion in copper in potable water
systems, Chapter 5 in Internal Corrosion in Water Distribution Systems, 2nd ed., AWWARF,
Denver, CO.
Ferguson, J.F., R. Ryder, E.A. Vik, and I. Wagner (1996) Mitigation of corrosion impacts, Chapter
8 in Internal Corrosion in Water Distribution Systems, 2nd ed., AWWARF, Denver, CO
Reports, Discussions, and Other Scholarly Papers
Ferguson, J.F. and D. Jenkins (1973) Discussion of "Pilot Plant Tests of a Phosphate Removal
Process," by Levin, Topal, Tarnay and Samworth, appearing mJWPCF, Vol 45, 552-555.
11
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Ferguson, J.F., G.F.P. Keay, and E.N.D. Amoo (1975) Combined PAC biological contact
stabilization treatment of municipal wastewater, Report to Metro.
Ferguson, J.F. and Brown and Caldwell Engineers (1976) Comparison of powdered activated
carbons for municipal wastewater treatment, Report to Amoco Corporation.
Ferguson, J.F., K.B. Parrish, D.W. Browne, S. Lellelid, and R.O. Sylvester (1977) A study of
wastewater handling, holding, and disposal from Washington State ferries, Washington State
Highway Department Research Program Report, Vol 27, 1.
Ferguson, J.F. (1979) Discussion of "AlkalinityA Neglected Parameter" by Neilson and
Bundgaard, Prog. Water Technology.
Horner, R.R., S.J. Surges, J.F. Ferguson, B.W. Mar, and E.B. Welch (1979) Highway runoff
monitoring: The initial year, May 1977-August 1978, Highway Runoff Water quality Research
Project Report 2, Department of Civil Engineering, University of Washington.
Vause, K.H., J.F. Ferguson, and B.W. Mar (1980) Water quality impacts associated with leachates
from highway woodwaste embankments, Highway Runoff Water Quality Research Project 4,
Department of Civil Engineering, University of Washington.
Asplund, R., J.F. Ferguson, and B.W. Mar (1980) Characterization of highway runoff in
Washington State, Highway Runoff Water Quality Research Project 6, Department of Civil
Engineering, University of Washington.
Banerjee, S., J.J. Horng, J.F. Ferguson, and P.O. Nelson (1988) Field scale feasibility study of
electro-kinetic remediation, Final Report, EPA CR811762-01, August.
Reiber, S.R., M.M. Benjamin, and J.F. Ferguson (1988) Internal corrosion within the Everett
distribution system, Technical Report, prepared for Department of Public Works, City of Everett,
March.
Benjamin, M.M., S.H. Reiber, J.F. Ferguson, E.A. Vanderwerff, and M.W. Miller (1990)
Chemistry of corrosion inhibitors in potable water, AWWARF report.
Ferguson, J.F. (1993) Anaerobic and Aerobic Biological Treatment of Bleaching Effluents to
Remove Chlorinated Organics, The Chlorine Institute, Washington, D.C.
Edwards, M., T.E. Meyer, J. Rehring, J. Ferguson, G. Korshin, and S. Perry (1996) Role of
inorganic anions, NOM, and water treatment processes in copper corrosion, American Water
Works Research Foundation, Denver, CO, 152 pp.
Ferguson, J.F. (1996) Have we bitten off more than we can chew, or is environmental engineering
more than we thought it was? Water Environment Research, 68:3, 259.
Ferguson, J.F. (1997) The system is the thing, Water Environment Research 69:6, 1065.
Korshin, G.V., J.F. Ferguson, A.N. Lancaster and H. Wu (1999) Corrosion and Metal Release for
Lead Containing Materials: Influence of Natural Organic Matter and Corrosion Mitigation,
AWWARF report, Denver, CO. 176 pp.
Ballapragada, B.S., Stensel, H.D., J.F. Ferguson, V.S. Magar, J.A. Puhakka (1998) Toxic
Chlorinated Compounds: Fate and Biodegradation in Anaerobic Digestion, Water Environ. Res.
Foundation, Project 91-TFT-3
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Newton, C.D., H.D. Stensel, J.F. Ferguson, (1999) Discussion of "A systematic artifact that
significantly influences anaerobic digestion efficiency measurement, by S.S. Beall, D. Jenkins,
S.A. Vidanage, Wat. Environ. Res. 71, 1257-58.
Borton, D., Ferguson, J., Fisher, R., Hall, E., Hall T., Joutijarvi, T., Luonsi, A. Munkittrick, K.,
and M. Priha (2004) 2003 IWA Symposium and Fate and Effects Conference, Paperi ja Puu, 86:5,
346-348.
Ferguson, JF (2004) Engineering Controls for Ballast Water Discharge: Developing Research
Needs, Report of an NSF-sponsored workshop.
Sponsored Research since 1985
Funded (current funding in bold)
8/85-6/88 Treatment of Waste Contaminated Ground by Electro-Kinetics (Co-Pi, Banerjee), EPA,
$255,000.
9/85-3/88 Chemistry and Application of Corrosion Inhibitors in Potable Water (Co-Pi, Benjamin),
AWWA Research Foundation, $120,000.
6/85-11/88 Transient Response Studies and On-Line Control in Anaerobic Wastewater Treatment
Reactors (Co-Pi, Benjamin and Ricker), NSF, $330,000.
1984-1990 Monitoring Water Quality (Co-Pis, Benjamin, Spyridakis), EPA, $350,000.
11/86-12/87 TFSC Model Development and Technical Assistance (Co-Pi, Stensel, Benjamin), Metro,
$89,000.
5/87-10/87 Corrosion Evaluation in the Everett Water Supply System (Co-Pi, Benjamin), City of
Everett, $34,000.
6/87-11/87 Evaluation of Dellchem Treatment at Tacoma North End (Co-Pi, Stensel), WA Dept. of
Ecology, $35,000.
5/88-9/89 Evaluation of Pretreatment for Discharge of Cedar Hills Leachate to the Metro Sewer
System (Co-Pi, Benjamin), King County (as subcontract to QGNF Co), $207,000.
8/88-7-90 Toxics Biodegradation in Municipal Wastewater Treating Using Fermentation, Anoxic
and Anaerobic Process Modifications (Co-Pi, Stensel), EPA, $239,000.
10/89-10/93 Advanced Biological Treatment Technology to Reduce Health Risk of Halogenated
Organic Contaminants (Co-Pis, Stensel, Strand, Herwig), NIEHS, $1,020,000;
4/92-4/95 $900,000;
4/95-4/00 $1,000,000
4/00-4/06 currently $183,000 per year
6/90-7/92 Advanced Biological Treatment of Bleaching Wastes, The Chlorine Institute, $208,000.
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6/91-6/94 Biodegradation of Poly chlorinated Biphenyls and Poly cyclic Aromatic Hydrocarbons in
Contaminated Marine Sediments (Co-Pis, Staley, Herwig), Office of Naval Research,
$375,000.
9/92-9/94 The Role of Inorganic Anions and Natural Organic Matter in the Corrosion of Copper
Pipe (Co-Pi, Marc Edwards, U. CO), AWWARF, $200,000.
3/92-3/95 Dehalogenation of Organic Pollutants in Anaerobic Digestion (Co-Pi, Stensel), METRO,
$125,000, WERF, $362,000.
4/92-4/96 Bioremediation of Marine Sediments (Co-Pi, Stensel), Office of Naval Research,
$210,000.
9/94-9/96 Corrosion and Metal Release for Lead-Containing Materials: Influence of Natural
Organic Matter and Corrosion Mitigation, AWWARF, $200,000.
10/94-9/04 Graduate Fellowships and Advanced Wastewater Research, (Co-Pi, Stensel) King Co.
Department of Natural Resources, currently $101,000 per year
3/95-7/01 Tools for Evaluating the Effects of Subsurface Restoration Technologies on Uncertainty
and Risk Reduction, subproject of Consortium for Risk Evaluation with Stakeholder
Participation, (Co-Pi, Stensel, Massmann) U.S. Dept. of Energy, $150,000 per year.
6/96-6/97 Pentachlorophenol Treatment Alternatives, Western Wood Preservers Institute, $25,000.
12/00-12/03 Post Optimization Lead and Copper Control Monitoring Strategies, AWWARF #2679,
(Co-Investigator, with Korshin [G. Kirmeyer of Economic & Engineering Services, Inc. is
PI]) $400,000 total project.
10/01 -9/02 RM-03 Control of Contaminant Migration, CRESP, Department of Energy, $71,422, PI.
6/02-9/05 Tank Waste Initiative, CRESP, Department of Energy, $89,000, UW budget supporting
my activities (with Korshin)
3/03-2/04 Engineering Controls for Ballast Water Discharges: A Workshop to Develop Research
Needs, NSF, $84,000.
10/03-9/06 Acetoclastic and Hydrolytic Activity in Anaerobic DigestionKeys to Process Stability
and Process Control, NSF, $505,000. (PI with Stensel and Stahl).
5/05-4/08 Fundamental Mechanisms of Lead Oxidation: Effects of Chlorine, Chloramine and
Natural Organic Matter on Lead Release in Drinking Water, NSF, $477,011. (Co-Pi with
Korshin)
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Project Reports (reports to sponsors)
Some, not all, are listed in "Reports, Discussions, Other Scholarly Publications" above
Invited Lectures and Seminars, last 10 years
Lecture at Duke University, 1988.
Seminar on Bleaching and the Environment, Pacific Northwest TAPPI, Seattle, WA, 1988.
Paper presented at American Society of Microbiology Northwest Meeting, Seattle, WA, 1989.
Berg Lecture, Department of Civil Engineering, University of Washington, 1990.
Lecture at Workshop on Corrosion Monitoring and Control, Oslo, Norway, 1990.
Lecture at University of Aalborg, Denmark, 1990.
Lecture at Purdue University, 1990.
Paper presented at TAPPI Environmental meeting, Seattle, WA, 1990
Lecture to Department of Ecology engineers, Redmond, WA, 1990.
Position paper presented at National Conference on Environmental Engineering Education, Corvallis,
1991
Lecture at Wastewater Technology Centre, Hamilton, Ontario, 1992
Speaker at EPA Workshop on Lead and Copper Rule, Chicago, IL, 1992
Lectures on Anaerobic Treatment of Forest Industry Wastewaters at Nanjing Forestry University,
Nanjing, China April, 1992
AWWA Conference on Lead and Copper Rule, Seattle, WA, 1993.
Speaker at Oregon Graduate Institute seminar, 1994
Lectures on Anaerobic Treatment of Industrial Wastewaters at Chengdu University of Science and
Technology, Chengdu, China April, 1994
Speaker at WERF Symposium, Miami Beach, FL, 1995.
Biological Dehalogenation in Marine Sediments, ONR Workshop, Bethesda, MD, 1996
15
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Applied Microbiology: Anaerobic Processes, CRESP Symposium, Seattle, WA, 1996
Invited speaker, Nessling Symposium on Bioremediation, Helsinki, Finland, 1998
Invited speaker, 4th Finnish Conference of Environmental Sciences, Tampere, Finland, 1999
Presented Doctoral Course on Advances in Biological Wastewater Treatment at Tampere University
of Technology, Tampere, Finland, May, 1999
Speaker at Civil Engineering Departmental Seminar, University of Minnesota, April, 2001
Presentations Given at Conferences, last 10 years
3rd IAWPRC Symposium on Forest Industry Wastewaters, Tampere, Finland, 1990.
AWWA Water Quality Technology Conference, San Diego, 1990.
TAPPI Environmental Conference, San Antonio, TX, 1991.
Air and Waste Management Association Conference, Vancouver, B.C., 1991.
TAPPI Environmental Conference, Boston, MA, 1993.
4th IAWQ Conference on Forest Industry Wastewater, Tampere, Finland, 1993.
AWWA Annual Conference, Atlanta, 1997
12th Annual WEF Residuals and Biosolids Management Conference, Bellevue, 1998
WEF Annual Conference, Orlando, 1998
Professional Society Membership
American Association for the Advancement of Science, since 1966
American Chemical Society, 1970-1980
Association of Environmental and Science Engineering Professors, since 1971
American Society of Civil Engineers, since 1963
American Society of Limnology and Oceanography, 1969-1980
American Water Works Association, since 1975
International Water Association, since 1990
TAPPI (Technical Association of the Pulp and Paper Industry), since 1980
Water Environment Federation, since 1966
16
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Professional Society and Other Service
AWWA Student Activities Committee, 1974-1977, Member Control Group, 1980-82
AEEP Distinguished Lecturer Committee, 1974-78, Chair 1978
WPCF Water Reuse Committee, 1974
Program Committee, ASCE-EED National Conference, Chairman, 1975-76
ASCE-EED Sessions Committee, 1976-77
AEEP Board of Directors, 1978-81
ASCE-EED Publications Committee, Acting Editor, Jour. Environ. Engr. Div., 1978-82
WPCF Awards Committee - H.P. Eddy Award, 1978-82, '84-87, Chair, 1987
WPCF Program Committee - Research Symposium Subcommittee, 1978-82
AWWA Corrosion and Stability Research Committee, Chairman, 1980-84, Member 1985-1992
AWWA/Engler Bunte Joint Committee on Corrosion in Water Systems, 1983-86, '92-95
Scientific Programme Committee, IAWPRC Symposium on Forest Industry Wastewater,
1989-90, 91-92, 95-96, 99.
Chair, Remediation of Solvents in Subsurface Environments Research Symposium, NIEHS, 1996
Management Group, IWA Specialty Group on Forest Industry Wastewaters, 1990-present
6th National Conference on Environ. Engr. Education, Steering Committee 1990-93
TAPPI Water Quality Committee, 1991-1995
AWWA Research Division Board of Trustees, 1992-present, Vice-Chair, 1995-97, Chair, 1998
-2001, Technical and Educational Council, member 1998-2001.
Editorial Board of Review for Water Environment Research, 1995-1999
Chair, Organizing and Program Committees, 7th IWA Symposium on Forest Industry Wastewaters,
June 2003, Seattle,WA
Member, ScientificCommittee, 8th IWA Symposium on Forest Industry Wastewaters, April 2006,
Vitoria, Brazil
Review panel, NIEHS Superfund Basic Research Program program projects, September, 2004
Participant, Technical Workshop on Ballast Water Management for Vessels Declaring No Ballast
Onboard, U.S. Coast Guard, Cleveland, May, 2005
Participant, Evaluating Ballast Water Treatment Systems Onboard Ships, Pacific Marine Fisheries
Commission, Portland, June, 2005
Review panel, NSF IGERT preproposal (BES program), April 2004, Washington DC
Reviews Made-typical for last 10 years
Journal Number
Water Research 5/yr
Environmental Health Perspectives 1 /yr
Environmental Science and Technology 3/yr
Journal of Environmental Engineering, ASCE 3/yr
Journal of American Water Works Association 2/yr
Water Environment Research 3/yr
(on Editorial Board of Review through 9/99, handling -30 papers per year)
other journals (e.g. Biotech. Bioengr., Can. J. Microbiol., Biodegradation) ~3/yr
Proposals:
17
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Proposal Review Panels, Environmental Engineering, EPA, 1995, 1997, NSF 2001, 2002, 2005
others (NSF, Canadian NSERC, Hong Kong, Korea and Singapore research agencies,
regional agencies and foundations) ~4/yr
Awards and Honors
National Merit Scholar, 1959-1963
TauBetaPi, 1962
AEC Fellowship in Nuclear Science and Engineering, 1963-1964
EPA Predoctoral Fellowship, 1966-1969
EPA Postdoctoral Fellowship, 1969-1970
H.P. Eddy Award for Outstanding Research (Water Pollution Control Federation), 1974
H.P. Eddy Award for Outstanding Research (Water Pollution Control Federation), 1978
H.P. Eddy Award for Outstanding Research (Water Pollution Control Federation), 1984
Award for Best Research Paper, American Water Works Association, 1984
Academic Advisor to winner of 1984 AWWA Academic Achievement Award for best
doctoral dissertation, 1984
Award for Outstanding Publication, American Water Works Association, 1988.
Award for Best Distribution System Paper, American Water Works, Association, 1990.
Berg Lecturer, Department of Civil Engineering, University of Washington, 1990.
Society of Scholars, Johns Hopkins University, 2002
Teaching, last 10 years
Course
CEWA 456
CIVE350
CEWA 556
CEWA 550
CIVE350
CEWA 470
CEWA 550
CEWA 456
CEWA 470
CEWA 556
CIVE350
CIVE 485
CIVE350
CEWA 550
CEWA 551
CEWA 550
No. of
Quarter Students
A1988
W1989
Sp 1989
A1989
W1990
W1990
A1990
A1990
W1991
Spl991
A1991
A1992
W1993
A1993
W1994
A1994
80
36
25
29
82
26
18
27
Course Title Instructor's
Avg of Items 1-4
Aquatic Chemistry
Envir. Engineering-Water & Air
Industrial Waste Treatment
Biological Waste Treatment
Envir. Engineering-Water & Air
Solid Waste Disposal
Microbiological Process Fund.
Aquatic Chemistry
Solid Waste Disposal
Industrial Waste Treatment
Envir. Engin. -Water & Air
Aquatic Chemistry
Envir. Engineering-Water & Air
Micro. Process Fundamentals
Biological Treatment Systems
Micro. Process Fundamentals
3.70
3.01
3.44
2.64
3.92
3.60
3.71
3.30
Form X
Form X
3.42
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CIVE350
CEWA 550
CIVE350
CEWA 550
CIVE350
CIVE350
CEWA 550
CIVE 485
CEWA 558
CEWA 550
CEWA 551
CIVE 3 50
CEE 540
CEE 541
CEE 549
CEE 500 C/D
CEE 482
CEE 544
CEE 3 50
W1995
A1995
W1996
A1996
W1997
A1997
A1997
W1998
S1998
A1999
W2000
S2000
A2000
W2001
S2001
S2001
A 2001
W2002
S2002
86
25
63
13
62
40
10
14
9
18
11
58
10
5
5
20
14
7
65
Envir. Engineering-Water & Air 3.34
Micro. Process Fundamentals 3.4
Envir. Engineering-Water & Air 3.5
Micro. Process Fundamentals 1.9
Envir. Engineering-Water & Air 3.5
Envir. Engineering-Water & Air 3.06
Micro. Process Fundamentals 2.88
Aquatic Chemistry 3.56
Industrial Waste Treatment
Micro. Process Fundamentals 3.43
Physical-Chemical Treatment Proc. 3.29
Envir. Engineering-Water & Air 3.22
Micro. Process Fundamentals
Biological Treatment Systems
Advanced Environ. Engr. Topics 3.25
EES/HWR Seminar
Wastewater treatment 3.12
Physical-Chemical treatment 4.32
Intro Environmental Engr. Science 2.6
Short Courses, Workshops, and Other Educational Programs
Teaching workshop, March 30, 2001
Chaired Doctoral Degrees
G. Lee Christensen (JHU)
Mark A. Anderson (JHU)
John Eastman
David N. Given
Ronald D. Hilburn
Sandra L. Woods
Foroozan Labib
Jao-Jia Horng
Simeon J. Komisar
Bhaskar Ballapragada
Krista M. Anders
Siwei Zou (continuing)
Jaana Pietari
Anne Conklin
Hyun-shik Chang (co-advise with Korshin) (continuing)
Chaired Master Degrees
David Refling (JHU)
Elaine Friebele (JHU)
David N. Given (JHU)
Thomas A. King (JHU)
George F.P. Keay
Sylvia Burges
1972
1974
1977
1978
1983
1985
1989
1993
1993
1996
2000
2002
2004
1974
1975
1975
1975
1975
1976
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Richard R. Spencer 1976
John P. Wilson-vanOsdel 1976
Cornelius J. Marx 1976
KarlB.Parrish, Jr. 1976
Steven M. Lellelid 1977
David W. Browne 1977
Ronald L. Horres 1977
Allan D.Kissam 1977
Ronald D.Hilburn 1977
Stephen M. Hart 1978
Mary S. Anderson 1978
Anne Crawford 1978
Kimberly A. Cox 1978
Sonthi Vannasaeng 1978
Wang-Cheng Tseng 1978
Mario Kato 1979
Paul Snyder 1979
Michael J. Brown 1980
KurtH. Vause 1980
Sandra L. Woods 1980
Carlos Herrera 1980
MarkB. Buggins 1980
Paul S. Snyder 1980
Brian J. Eis 1982
David R. Nitchals 1983
Michael S. Kuenzi 1984
Karl R. Nordqvist 1985
James C. Ebbert 1986
Ronald S. Sletten 1987
Chung Feng Chung 1987
ByungK. Maeng 1987
Sheila J. Baran 1989
Gregory L. Pierson 1989
Christopher A. Arts 1989
Yun-Peng Shih 1989
John Galasso 1989
Mary I. Rumpf 1989
EvaJonsson 1990
Dennis Ritter 1990
Laura Hodges 1991
Ronald A. LaFond 1991
Karl S. Bosworth 1992
William T. Leif 1992
Per H. Ollestad 1992
Patricia S. Perkins 1992
Ron L. Porter 1992
Grete Rasmussen 1992
John Ryding 1992
Sophia Gudmundsdottir 1993
AndyHaub 1993
Jean H. Lee 1993
Margareta Lundin 1993
Paivi Makinen 1993
GroD. Ofjord 1993
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Krista M. Anders 1994
Samuel A. L. Perry 1994
Stacy A. Koch 1995
Henning Mohn 1995
Matthew L. Hinck 1995
Kara Nelson 1996
Patricia A. Danowski 1997
Pamela A. Elardo 1997
Rebecca S. Maco 1997
HaoWu 1997
Alice Lancaster 1997
Michael Boyle 1997
SiweiZou 1997
Jaana M.H. Pietari 1999
Lisette L. Nenninger 1999
Cheryl Stadlman 1999
Janel Duffy 2001
Se-Yeun Lee 2002
Veronica Henzi (with J. Cooper) 2003
Pragya Singh (co-advise with G. Korshin) 2002
Jessica Satterberg 2004
Benni Jonsson (continuing)
Tom Chapman (continuing)
Dan Wang (continuing)
Virpi Salo (continuing)
Other Student Supervision (service on graduate degree committees):
not listed
Departmental Service, since 1988
1988 Civil Engineering Undergraduate Curriculum Review Committee
1988-1992 Chairman, Civil Engineering Undergraduate Education Committee
1988 Organizer, Evans Lectureship
1989-1991 Graduate Program Advisor, Environmental Engineering & Science
1997-1998 Chair, Centennial Reunion Planning Committee
1999-2000 Graduate Application Coordinator for Environmental Engineering & Science
2002-present Undergraduate Admissions and Scholarship Committee
2002-2003 Coordinator for Environmental Engineering and Science Area
2004-2005 Coordinator graduate admissions for Environ. Engin. Science
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College Service since 1988
1987-88 College Undergraduate Engineering Curriculum Review Committee
1991-present Valle Scholarship and Exchange Program, Associate Director
University Service since 1988
1990 Graduate School Review Committee for Environmental Health Ph.D.
Program
1997 Chair, Graduate School Review Committee for Department of Environmental Health
2003 Member, Graduate School Review Committee for School of Aquatic and Fishery Sciences
Community Service
Internal Corrosion Study Advisory Committee, Seattle Water Dept, 1975-76
Cedar-Tolt Watershed Management Advisory Committee, Seattle Water Dept., 1976-79
Toxicant Study, Scientific Advisory Panel, Municipality of Metropolitan Seattle, 1978-81
National Service, partial listing
Peer Review Panel for EPA Research Center at Illinois Institute of Technology, 1985
Western Regions Hazardous Substances Research Center, Scientific Advisory Board, 1985-92
EPA National Risk Management Laboratory Review Panel, 1997
American Water Works Association Research Foundation, member Materials Issues Group, 1998
NSF Review Panel, 2001, 2002, 2005
Other Service, since 1996
Department of Civil Engineering Review, University of British Columbia, 1996
Department of Civil Engineering, University of Portland, Advisory Committee to Envir. Engr. Program,
1998
Consulting Experience, since 1990
Corrosion impacts for San Francisco, Santa Cruz, and Los Angeles water systems, Camp, Dresser,
and McKee, Inc., 1990
Corrosion and blue water in East Bay MUD system; James M. Montgomery Engineers, 1990.
Corrosion evaluation for Santa Clara Valley Water District; Kennedy, Jenks, Chilton, 1991.
Corrosion evaluation for Portland Water Bureau; Economic and Environmental Services, Inc.,
1992-94
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Evaluate anaerobic bioremediation for Western Processing site, Landau Associates, 1993.
Consult on treatment of deicing wastewaters, Port Authority of Seattle, 1995.
Corrosion and red water evaluation for Tucson, AZ, CDM, 1996
Pollution of City Waterway, Tacoma, WA; Aitken, St. Louis, Siljeg, 1996-1997
Copper corrosion evaluation for Prescott, AZ, HDR Engineering, 1997
Evaluation of Anoxic Gas Flotation alternatives for King Co. DNR, Brown & Caldwell, 1999
Corrosion evaluation of treatment changes for Santa Clara Valley W.D., CDM, 1999
Corrosion study for corrosion inhibitors for City of Santa Cruz, CDM, 2000
Corrosion study for corrosion inhibitors and coagulant change for Santa Clara Valley Water
District, 2001
Court-appointed expert on corrosion field testing, Judge Peter Lichtman, L. A. Co. Superior Court,
February-July, 2001.
Evaluation of data from San Francisco PUC regarding turbidity in their transmission lines, CDM,
2002
Corrosion inhibition evaluation for CCWD/ City of Brentwood, CDM, 2004
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Education
B.S. -Civil Engineering,
University of Massachusetts/
Dartmouth (1982)
Registration
Professional Engineer:
Massachusetts (1988), Maine,
Connecticut, Rhode Island,
and New Hampshire
Carol A. Rego, P.E.
Vice President
Ms. Rego has 25 years of experience in water and water supply. Her expertise
includes treatability studies; process selection and drinking water research;
Safe Drinking Water Act (SDWA) compliance; water supply planning; and
water treatment plant evaluation, operations, and design.
Project Director/Technical Advisor. Ms. Rego serves as a senior project
director and technical advisor for several drinking water projects in the New
England Area including the Portland, Maine UV Disinfection Feasibility
study; Reading, Massachusetts NDMA evaluation; Springfield Water and
Sewer Commission optimization study; Lewiston and Auburn, Maine Safe
Drinking Water Act compliance evaluation; water treatment plant upgrade
for the City of Woonsocket, Rhode Island; and water quality consulting for
the Providence (Rhode Island) Water Supply Board, including a 2-year lead
and copper corrosion control optimization program.
Officer-in-Charge, City of Cambridge, MA Water Quality and Treatment
Consulting. Ms. Rego is overseeing various projects for the City including
optimization of mixing and water quality in the Payson Park finished water
storage reservoir; disinfection tracer studies for enhanced treatment; and
developing a long-term water supply strategy.
Officer-in-Charge, City of Newport, RI, Compliance Evaluation and Water
Treatment Plant Improvements Projects. In response to new and upcoming
drinking water regulations, the City of Newport undertook a comprehensive
treatment evaluation, culminating in a plan of coordinated improvements to
meet future regulations, as well as future water demands. The complexity of
the Newport supply, treatment and distribution system further added to this
challenge. This includes a complicated system of nine reservoirs having a
wide range in quality that can change quickly. It also includes two treatment
plants with different processes, one of which has equipment that is much
beyond its useful life. Finally, the distribution system includes several
pressure zones, several consecutive systems, and extended water age
concerns. Ms. Rego is directing the city's systematic approach to achieving
integrated treatment including:
Detailed evaluation of distribution system water quality interrelationships
between proposed disinfection modifications (chloramines) and corrosion
control treatment. This includes a year-long pipe loop study evaluating the
effects of various NOM-pH-Pb-ORP relationships.
Audit inspection of treatment plants to identify physical and reliability
deficiencies.
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Honors/Awards
Massachusetts Society of
Professional Engineers, Young
Engineer of the Year (1992)
Dexter Brackett Award, Most
Meritorious Paper: Journal of the
New England Water Works
Association (1997)
Carol A. Rego, P.E
Testing program including enhanced coagulation, organics removal
optimization (MIEX), DBF formation kinetics, alternate coagulants, and
alternate secondary disinfectant (chloramines).
Short-term improvements including the addition of chloramines for
secondary disinfection at both WTPs to reduce formation of disinfection
byproducts, optimization of existing processes for TOC removal and CT
compliance.
Multi-pronged testing program including pipe scale analyses; bench-scale
testing (chloramine decay, chlorine-to-ammonia ratio, DBF formation,
coupon testing for metal (lead) release, corrosion rates, and scale
formation); and limited pipe-loop testing.
Project Manager/Technical Manager, Lead and Copper Rule Corrosion
Optimization/Control Studies. Ms. Rego has helped several New England
utilities develop approaches for corrosion optimization under the Lead and
Copper Rule. These communities include Salem/Beverly, Needham, New
Bedford, Worcester, Wakefield, and Woburn, Massachusetts; Brewer,
Lewiston and Auburn, Maine; and Newport, Providence, Westerly,
Pawtucket and Woonsocket, Rhode Island. For the Rhode Island Department
of Health (RIDOH), she conducted a corrosion control study for the state's 43
small surface and groundwater systems. She also assisted many of these
communities with their public notification efforts.
Technical Manager, Lead and Copper Rule Corrosion Optimization/Control
Studies. Ms. Rego assisted the Salem Beverly Water Supply Board (SBWSB)
(Massachusetts) with optimization of their corrosion control treatment and
development of a regulatory compliance strategy. After many years of being
in compliance, the SBWSB exceeded the Action Level for lead. The program
included review of historical data, establishing sampling plans for
lead/copper (Pb/Cu) at the tap and water quality parameters (WQPs), bench-
scale testing of alternative corrosion treatment strategies, implementation of
the recommended treatment strategy, public notification/education program,
and routine sampling for WQPs and Pb/Cu following changes in treatment.
Technical Specialist, Lead and Copper Rule Compliance, Various Industrial
Clients. Ms. Rego conducted an engineering study to address lead and
copper concerns in the IBM East Fishkill (NY) West Complex distribution
system. This included development of a sampling and analysis plan to
evaluate water quality parameters in the West Complex system followed by a
detailed implementation plan for the recommended treatment modifications.
Ms. Rego also provided lead and copper rule drinking water regulatory and
technical expertise for a food processing facility located in Killingly,
Connecticut and the Pratt & Whitney manufacturing facility in Middletown,
Connecticut.
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Carol A. Rego, P.E
Project Manager, US Coast Guard Shipboard Technology Evaluation
Program (STEP). The STEP is designed to encourage the voluntary
installation and testing of onboard ballast water treatment systems on
merchant vessels by offering "equivalency" to the new ballast water
management regulation. The project includes: (1) A desktop assessment of
currently available and advanced prototype ballast water treatment systems
intended for use onboard vessels; (2) marine biology and civil engineering
Review Panel; and (3) assistance in the review and upgrade of STEP standard
documents.
Project Manager, Water Supply/Treatment Plan. For Manchester Water
Works (MWW) in New Hampshire, Ms. Rego directed a yearlong study to
develop a long-range view of MWW's water supply and treatment options
along with a plan for how to implement this vision. Ms. Rego reviewed
MWW's water supply situation from multiple perspectives ranging from
supply source adequacy to the deterioration of aging facilities. Her work also
included review of existing source and finished water quality data, the
existing treatment process, current and proposed regulations, evaluation of
the future Merrimack River supply quality, and establishment of treated
water quality goals. She developed a series of supply and treatment
alternatives that were evaluated on the basis of cost (capital, operational and
life cycle), overall effectiveness in meeting the established water quality goals,
and non-cost factors such as reliability, ease of operations, public acceptance,
and environmental compatibility. Ms. Rego continued as the project manager
for the design of the 50-mgd plant upgrade, which features ozone, new filters,
additional clearwell capacity, provisions for UV disinfection, and
improvements to the facility's electrical, structural and architectural systems.
Officer-in Charge, Water Distribution System and Water Treatment
Upgrade Projects. Ms. Rego oversaw a chloramine conversion project for the
City of New Bedford, Massachusetts, and the upgrade of a filtration plant for
the Town of Wakefield, Massachusetts. She helped both communities secure
State Revolving Loan Funding (SRF). Also for New Bedford, Ms. Rego is
overseeing a water main rehabilitation project involving 29,000 feet of main
replacement and relining. She is also responsible for completion of a
transmission main reinforcement program for New Bedford involving line
valve replacement on 42,380 feet of 48-inch cast iron and concrete main;
20,000 feet on twin 36-inch cast iron mains; and 22,750 feet of 42-inch concrete
main.
Task Manager, Ultraviolet Disinfection Fouling Study. For New York City,
Ms. Rego is the task manager for an ultraviolet disinfection fouling study for
the unfiltered Catskill and Delaware surface water supply systems. The 12-
month-long study will evaluate low pressure high output and medium
pressure UV reactors in side-by-side testing. The study objectives are to
investigate fouling potential on the exterior surfaces of lamp quartz sleeves
(with and without chlorine addition upstream of the UV reactors); evaluate
algae growth potential on surfaces distant from the UV lamps; independently
evaluate the performance of each reactor's sleeve cleaning system (i.e., the
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Carol A. Rego, P.E
cleaning systems for each reactor will not be compared to each other); and
compile O&M information (e.g., cleaning regime, personnel requirements,
etc.).
Task Manager, Water Quality and Treatability Studies. For New York City,
Ms. Rego was the task manager for the water quality and treatability studies
for the 1,900-mgd Catskill and Delaware surface water supply systems. She
developed testing protocols and associated water quality sampling plans, and
oversaw the direction and execution of a multi-year pilot study for the
presently unfiltered New York City supply. Her work included
accompanying source water quality studies to anticipate treatment challenges
and future regulatory compliance issues.
Project Manager, Enhanced Disinfection Study. Ms. Rego's work for New
York City also included a two-year disinfection study to investigate the use of
alternative disinfectants (ozone, chlorine dioxide, chlorine, and UV) for
primary disinfection under a continued filtration avoidance scenario. The
study determined the appropriate disinfectant dose and system configuration
to provide various levels of pathogen inactivation without subsequent
filtration. Other objectives included evaluating multiple, sequential
disinfectants for enhanced inactivation, determining the levels of
biodegradable organic matter and disinfection byproducts produced, and
assessing the impacts of an ozone disinfection alternative on the distribution
system.
Officer-in-Charge and Technical Director, Flint's Pond Microfiltration
Plant. Ms. Rego was the officer-in-charge for studies and design of a 1.6-mgd
microfiltration plant for the Town of Lincoln, Massachusetts. As part of this
work, she directed a 4-month pilot testing study for the town's presently
unfiltered surface water supply Flint's Pond. Her work also included source
water quality and SDWA compliance assessments, and State Revolving Loan
Funding (SRF). CDM provided construction management and inspection
services for the project, which recently went into operation in the summer of
2003.
Task Manager, Pilot Testing. For the Philadelphia Water Department (PWD),
Ms. Rego developed the protocols for a three-year pilot-testing program at its
Baxter and Belmont plants. The focus of the first year was on short-term, low-
or no-capital cost modifications to optimize the existing plants in light of
regulatory compliance and cost issues. The second phase of the testing
program evaluated alternative oxidant and advanced clarification methods.
PWD will evaluate alternative disinfectants (focusing on ozone) in the third
phase.
Project Manager, Information Collection Rule Program. Ms. Rego was the
project manager for Information Collection Rule (ICR) sampling programs for
the City of Brockton, Massachusetts, and for the Massachusetts Water
Resources Authority (MWRA), Boston. She also directed ICR pilot studies for
the City of New Bedford, Massachusetts, and rapid small-scale column testing
CDM
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Carol A. Rego, P.E
(RSSCT) studies for Brockton, Massachusetts, both evaluating granular
activated carbon (GAC) for precursor removal.
Technical Advisor, Water Quality Assessment. Ms. Rego was a technical
advisor for the Drinking Water Quality Assessment and Improvement
Program for the District of Columbia Water and Sewer Authority (WASA).
Her work included reviewing and evaluating water treatment and
distribution system water quality and operating practices to develop
recommendations and an implementation plan to improve the District's
compliance with the Total Coliform Rule (TCR).
Task Manager, Distribution System Water Quality Improvement Program.
Also for MWRA, Ms. Rego was the special task manager for the distribution
system water quality improvement program. She developed a program to
revise the primary and secondary disinfection practice to improve
distribution system residuals and improve compliance with the Total
Coliform Rule. System features included open reservoirs, rechlorination
following initial chloramination, and simultaneous implementation of new
corrosion control treatment. She participated in a water quality workshop for
MWRA staff and community representatives on integrating corrosion control
and disinfection improvements.
Project Manager, Water System Improvements. For water system
improvements conducted for the City of Worcester, Massachusetts, Ms.
Rego's duties included project coordination and preparation of plans and
specifications for a $65 million capital improvement project being constructed
under eight construction contracts. These contracts include a 50-mgd water
filtration plant, pump station modifications, water storage tanks, raw and
finished water transmission mains, and distribution system improvements.
Also included are design, construction, and operation of the pilot testing
facility; preliminary design; detailed site selection studies; plant design
criteria; plant layout; analysis of distribution systems; storage and pumping
facilities; and cost-effective analyses. Ms. Rego was responsible for all
permitting and public education requirements associated with the project.
Project Manager, Operator Training and Startup. Ms. Rego developed and
conducted operator training and oversaw the start-up of the Worcester water
filtration plant, featuring on-line particle counters for each of the eight filters,
and the source and finished water. The plant achieves greater than 3-log
particle removal in the Giardia and Cryptosporidium size range and exceeds all
production and water quality goals.
Technical Director, Water Treatment Plant Studies. Ms. Rego was also the
technical director for the Pilot Plant Studies, Quittacas WTP (45 mgd) in New
Bedford, Massachusetts. The project evaluated the technical, water quality,
and cost issues to convert from full conventional treatment to direct filtration
and to convert from free chlorine to chloramine residual disinfection.
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Carol A. Rego, P.E
Project Engineer, Water System Improvement Project. Ms. Rego was project
engineer for the final design of Worcester's major water system
improvements project. This project received an ACEC award for engineering
excellence. She prepared plans and specifications and provided
multidisciplinary coordination for eight construction contracts that included a
50-mgd water filtration plant, five water storage tanks, pump station
modifications, raw and finished water transmission mains, and distribution
system improvements.
Project Engineer, Facilities Plan. Ms. Rego also served as project engineer for
a facilities plan and preliminary design for ozone primary disinfection
facilities for the Portland Water District in Maine. In this role, she was
responsible for the technical completion of the project, including site selection
studies and facilities layout. She was also project engineer for an SDWA
Impact Study for the Bridgeport Hydraulic Company in Connecticut.
Process Consultant, Water Treatment Plant. Ms. Rego conducted a water
treatment plant process study for the Town of Weymouth, Massachusetts. She
was also a project engineer for a 10-mgd water treatment facility at Ludlow
Reservoir in Springfield and for water treatment studies for the Champlain
Water District in South Burlington, Vermont.
Process Consultant, International Water Treatment Plant Projects. Her
international work includes serving as process consultant for the Treatment
Process Upgrade Program, Public Utilities Board, Republic of Singapore.
Other international work includes serving as a Process Consultant for Siu Ho
Wan (40 mgd), Ma On Shan (60 mgd), and Ngau Tarn Mei (120 mgd)
Treatment Works, Hong Kong Water Supplies Department.
Professional Activities
Organizing Committee, National Academy of Engineering, 2007 US Frontiers
of Engineering Symposium, Redmond, WA.
AWWA Research Foundation, Research Advisory Council, 1998-2004
AWWA Research Foundation, Research Chair, Customer Workgroup of the
Research Advisory Council, 1999 and 2000
AWWA Research Foundation, Research Chair, Environmental Leadership
Workgroup of the Research Advisory Council, 2001-2003
U.S. Environmental Protection Agency (USEPA) National Drinking Water
Advisory Council (NDWAC) Working Group on Research, 2000-2002
AWWA Research Foundation, Project Advisory Committee for Improvement
of the Ozonation Process Through the Use of Static Mixers, 1998-2000
COM
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Carol A. Rego, P.E
Invited Participant - Drinking Water Research Needs Expert Workshop,
sponsored by USEPA and AWWA Research Foundation, Leesburg, Virginia,
September 1999
AWWA Research Foundation, Project Advisory Committee for Optimizing
Filtration in Biological Filters, 1995-1999
Publications/Presentations
Case Studies in the Integrated Use of Scale Analyses to Solve Lead Problems, with
M.R. Schock, National Risk Management Research Laboratory, USEPA,
Cincinnati, Ohio, 2007 AWWA Distribution Research Symposium, Reno, NV,
March 3, 2007.
Understanding the Relationship Between Organic Precursor Fractions and
Formation ofNDMA and CNX in a Ground-water Supply, with D.A. Reckhow,
University of Massachusetts, proceedings of the AWWA Water Quality
Technology Conference, Denver, Colorado, November 6, 2006.
Two Approaches to Address Calcium Carbonate Scaling Resulting from Optimal
Corrosion Control Treatment, AWWA Inorganic Contaminants Workshop,
Austin, Texas, January 31, 2006.
Simultaneous Compliance Issues with Corrosion Control BAT: More than Just
Primary Standards, with W.T. Wanberg, Town of Needham and M.R. Schock,
U.S. EPA, AWWA Water Quality Technology Conference, Quebec City,
Quebec, November 2005.
Case Studies - LCR and DBPR Simultaneous Compliance, Virginia AWWA
Section Drinking Water Quality Committee Seminar, Richmond, VA, April 13,
2005.
Case Study: One City's Long-Term Strategy to Balance Multiple Water Quality
Objectives, with James Ricci, Water Superintendent and Charles Kennedy,
Assistant Superintendent, City of New Bedford, presented at the New
England Water Works Association Water Quality Symposium, Boxborough,
MA, May 19, 2005.
Lead and Copper Corrosion Control Theory Update, with M.R. Schock, U.S. EPA,
Cincinnati, OH, NEWWA Spring Joint Regional Conference and Exhibition,
Worcester, Massachusetts, April 6, 2005.
Evaluating and Improving Water Quality in Distribution Storage Reservoirs, with
T.W. D. MacDonald, Manager of Water Operations, Cambridge Water
Department, presented at the NEWWA Spring Joint Regional Conference and
Exhibition, Worcester, Massachusetts, April 6, 2005.
Controlling Both Calcium and Lead: A Unique Situation in New England, with
William T. Wanberg, New England Water Works Association Annual
Conference, Newport, Rhode Island, September 21, 2004.
COM
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Carol A. Rego, P.E
Selection, Construction and Operation of Membranes for a Small System, New York
Section of the American Water Works Association Spring Meeting, Saratoga
Springs, New York, April 29, 2004.
Chloramine Conversion: What Distribution System Changes Should You Expect?
with James Ricci and Charles Kennedy, NEWWA Spring Joint Regional
Conference and Exhibition, Worcester, Massachusetts, March 31, 2004.
Prepare Now for Public Notification, NEWWA Spring Joint Regional Conference
and Exhibition, Worcester, Massachusetts, April 2002.
Implementing the First Surface Water Micro filtration System in Massachusetts,
with L. Sorgini, proceedings of the American Water Works Association
Membrane Technology Conference, San Antonio, Texas, March 2001.
Manchester's Water Supply and Treatment Plan, with David B. Paris, NEWWA ~
NHWWA ~ GMWEA Meeting, West Lebanon, New Hampshire, January
2001.
The Feasibility of Constructing a Medium-Pressure UV Facility for New York City's
Catskill and Delaware Supplies, with O. Schneider, J. Herzner, D. Nickols, and
D. Malanchuk, proceedings of the American Water Works Association Water
Quality Technology Conference, Salt Lake City, Utah, November 2000.
Micro filtration: Meeting Water Quality Challenges for Small Systems, with L.
Sorgini, proceedings of the American Water Works Association Annual
Conference, Denver, Colorado, June 2000.
Impacts of Corrosion Control on Heavy Metals Concentrations: Three Years of
Operating Experience, New England Water Environment Association Spring
Conference, Bretton Woods, New Hampshire, June 5, 2000.
Treating Waste Filter Backwash with Low Pressure Membranes, New England
Water Works Association Water Quality Symposium, Boxborough,
Massachusetts, May 2,2000.
Ultraviolet Light (UV) Disinfection for Drinking Water, with D. Nickols, Edwin
C. Tifft Jr. Water Supply Symposium, New York Section of the American
Water Works Association, Liverpool, New York, October 20,1999.
Micro filtration: Meeting Water Quality Challenges for Small Systems, with L.
Sorgini, New England Water Works Association Annual Conference,
Burlington, Vermont, September 22,1999.
A New Look at an Old Technology: Slow Sand Filtration, with S. Tarallo,
proceedings of the American Water Works Association Annual Conference,
Chicago, Illinois, June 1999.
COM
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Carol A. Rego, P.E
Worcester Corrosion Control Retrofit-An Example of a Project Partnership
Approach, with R. Hoyt and P. Guerin, Joint Regional Operations Conference,
New England Water Works Association, Worcester, Massachusetts, April 7,
1999.
Alternatives to Achieve Enhanced Disinfection for New York City, with J. Herzner
et al., Proceedings, International Ozone Association, Pan American Group
Annual Conference, Vancouver, British Columbia, October 1998.
Newsletters Are Consumer Friendly, Joint Regional Operations Conference, New
England Water Works Association, Marlborough, Massachusetts, April 1,
1998.
Implementing Corrosion Control Treatment: Balancing Water Supply and
Wastewater Needs Through a Partnership Approach with R. Moylan and T. Walsh,
Proceedings, WEFTEC '97, Chicago, Illinois, October 1997.
Do Interim Improvements Prior to Permanent Facility Construction for SWTR
Compliance Provide Worthwhile Public Benefit? with S. Seckinger et al.,
proceedings of the American Water Works Association Annual Conference,
Atlanta, Georgia, June 1997.
Round Robin HAA Testing Prompts Uncertainty in USEPA Method 552.1, with S.
Seckinger and J. Occhialini, proceedings of the American Water Works
Association Water Quality Technology Conference, Boston, Massachusetts,
November 1996.
Balancing Corrosion Control, Disinfection and Distribution System Water Quality
for Boston, with B. Johnson, et al., proceedings of the American Water Works
Association Water Quality Technology Conference, Boston, Massachusetts,
November 1996.
Pushing the Envelope: Integrating Ultra-High Clarification and Filtration Loading
Rates, American Water Works Association, Engineering and Construction
Conference, Denver, Colorado, March 1996.
Ozone Applications for Filtration and Non-Filtration Alternatives, International
Ozone Association Pan American Group Conference on Ozone for Drinking
Water Treatment, Cambridge, Massachusetts, November 1995.
Evaluating Contract Operations for a New Water Filtration Plant, with R. Moylan
and J. Ridge, presented at the American Water Works Association Annual
Conference, Toronto, Canada, June 1996.
Washwater Recycle Optimization, presented at the American Water Works
Association Annual Conference, Anaheim, California, June 1995.
Dissolved Air Flotation Optimization: A Case Study, with D. Nickols, et al., poster
presentation at the American Water Works Association Annual Conference,
Anaheim, California, June 1995.
COM
-------
Carol A. Rego, P.E
Pilot Scale Evaluation of Residuals Management Options, with S. Seckinger, et al.,
poster presentation at the American Water Works Association Annual
Conference, Anaheim, California, June 1995.
Treatment Process Strategies to Meet Varying Water Quality Goals: Evaluating the
Costs and Benefits, poster presentation at the American Water Works
Association Water Quality Technology Conference, San Francisco, California,
November 1994.
The Crypto Challenge: Optimizing Treatment For Cryptosporidium Control, New
England Water Works Association Annual Conference, Montreal, Quebec,
September 1994.
Small System Compliance: CT Versus DBFs, Proceedings of the American Water
Works Association Annual Conference, New York City, June 1994.
Small System Compliance: CT Versus DBFs, Proceedings of the American Water
Works Association Engineering Design Conference, Cincinnati, Ohio, March
1994.
Water Treatment Plant Siting: Balancing Public, Environmental and Engineering
Needs, with R. Moylan et al., Proceedings of the American Water Works
Association Annual Conference, San Antonio, Texas, June 1993.
Optimization and SDWA Compliance at a New England Water Treatment Plant,
with J. Buckley et al., New England Water Works Association, Randolph,
Massachusetts, December 1992.
Review of the New Lead and Copper Regulations, Maine Water Utilities
Association, Old Town, Maine, October 1991.
Removal of Total Oxidant Species of Chlorine Dioxide Disinfection by Granular
Activated Carbon, with J. Thompson, Proceedings of the American Water
Works Association Annual Conference, Cincinnati, Ohio, June 1990.
Evaluation of Alternative Water Supplies for Worcester, Massachusetts, New
England Water Works Association, Milford, Massachusetts, May 1988.
Ozone-Direct Filtration for the Worcester Water Supply, with P. Prendiville et al.,
Proceedings of the American Water Works Association Annual Conference,
Kansas City, Missouri, June 1987.
COM
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JOHN S. YOUNG, JR.
Home: 109 Kingsdale Avenue
Cherry Hill, New Jersey 08003
856-424-0718
Business: American Water
1025 Laurel Oak Road
Voorhees, New Jersey 08043
856-346-8250
Education: B. S. Civil Engineering, Duke University, 1975;
M.S. Environmental Engineering, University of North Carolina at Chapel Hill,
August 1977 (two year program)
Professional Summary
John Young joined the American Water System in 1977 as the Director of Water Quality for the Eastern
Division. He held increasingly responsible positions in engineering and water quality and in 1991 was
named Vice President - Engineering. In this position, he was responsible for planning, capital program
delivery, operational enhancements and employee development. Mr. Young has been active in and held
leadership positions in a number of professional and civic organizations. Mr. Young has more than 25
years of experience in the planning, design, construction management and operation of water and
wastewater systems. He has also provided expert testimony and lectures in those areas. During 2000 and
2001, Mr. Young was the integration lead for the major acquisition of Citizens Water Resources.
John Young is Chief Operating Officer (COO) of American Water and holds a seat on the company's
Board of Directors. He was responsible for a wide range of corporate functions, including identifying and
implementing operational improvements; managing the Americas Region capital program; and directing
risk management in the areas of health and safety, security and event management. He was also
responsible for environmental compliance, management, and stewardship; engineering; research and
technology; and assessment of commercial and growth initiatives.
Young is an active member of several professional organizations, including a Board Member of the
Design/Build Institute of America and past New Jersey AWWA Section Chair and Fuller Awardee. He
also serves on the USEPA National Drinking Water Advisory Council (NDWAC).
Employment Record:
Chief Operating Officer American Water
10/05 - Present Responsible for developing and integrating the Company's
strategic plan including establishing balance between the
company's immediate business goals and long-term vision,
developing and implementing policies, procedures and
standards, as well as maintaining and enhancing the
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Vice President - Operations and
Investment Performance
11/03-10/05
company's image and quality service.
American Water
Responsible for the following functions/activities:
1) Identifying and implementing operational
improvements, and efficiencies and best practices
across the business;
2) Managing the Americas Region $600M capital
program;
3) Risk Management - Health & Safety, Security and
Event Management;
4) Environmental compliance, management and
stewardship;
5) Engineering;
6) Research & Technology.
7) Assessment of commercial and growth initiatives.
Vice President - Technical Services
1/03-11/03
Vice President - Engineering
4/91 - 1/03
Director - Engineering Design
1/86 - 4/91
American Water
Responsible for managing the American Water technical
services including the engineering, environmental
management and research functions. Additionally,
responsible for improving business performance through
identifying and implementing operational efficiencies,
material procurement and energy management initiatives.
Provide technical leadership for commercial opportunities
to maximize value and performance.
American Water Works Service Co., Inc.
Responsible for managing the engineering function of the
American Water System. This includes the preparation of
comprehensive planning studies for system operations in
twenty-two (22) states and the design, design overview and
construction management or projects involving water
supply, treatment, pumping, distribution and transmission
facilities. Responsibilities also include development of
engineering standards, project management procedures,
employee development and business development.
American Water Works Service Co., Inc.
Responsible for managing engineering design for American
System Engineering Office. Responsibilities include:
1) Review and approval of in-house design of water
treatment, pumping and storage facilities.
2) Development of detailed design concepts and
coordination of water works design and construction.
3) Pilot plant testing and start-up of new or expanded
facilities.
4) Instruction at training seminars.
5) Technical presentations.
6) Expert testimony.
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Director - Engineering Planning
9/84 - 12/85
Supervising Engineer
10/82 - 9/84
System Environmental Engineer
12/79 - 10/82
System Water Quality Engineer
10/78 - 12/79
Director of Water Quality
Eastern Division
9/77 - 10/78
Teaching Assistant
9/76 - 6/77
Student Research Assistant
9/75 - 9/76
American Water Works Service Co., Inc.
Responsible for managing engineering planning for
American System Engineering Office. This group
developed Comprehensive Planning Studies for water
systems which included water demand projections and
regional water supply plans, analysis of sources of supply
and production facilities and modeling of distribution
systems.
American Water Works Service Co., Inc.
Served as project engineer for the major design projects
within System Engineering Office and supervised
personnel on other design and planning projects.
American Water Works Service Co., Inc.
Project engineer with primary responsibility for process,
hydraulic, chemical feed and instrumentation and control
design and coordination of structural, electrical and HVAC
for new and renovated water works facilities. These
facilities included turbidity removal, greensand filtration,
lime softening, GAC adsorption, air stripping and residual
solids processing.
American Water Works Service Co., Inc.
Evaluated the performance and efficiency of treatment
facilities for American System Water Quality Office.
American Water Works Service Co., Inc.
Responsible for the review and implementation of
recommendations to improve finished and raw water
quality, treatment efficiency and laboratory.
University of North Carolina
Involved the preparation and instruction of laboratory
exercises for three graduate level courses in water and
wastewater unit processes.
Bogue Sound Water Quality Study
University of North Carolina
Duties included field sampling and collection of
background data to develop recommendations for pollution
abatement.
Assistant Engineer
1975,1976 (part-time)
Professional Certifications
Professional Organizations:
Wiggins-Rimer & Associates
Collection and analysis of watershed and stream flow data
for 208 regional water quality/quantity planning studies.
Registered Professional Engineer in multiple states.
National Drinking Water Advisory Council (2001- )
NDWAC Affordability Workgroup
NDWAC Water Security Workgroup
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American Water Works Association
Standards Council Member
Chair - AWWA/ASDWA Additives
1992-1994 New Jersey Section Program
1994-1999 New Jersey Section Board of Trustees
1997 New Jersey Section Chair
1994 Fuller Award Recipient
American Society of Civil Engineers
Design/Build Institute of America - Board Member
Civic: Trinity Presbyterian Church
1989 - 1992 Board of Deacons
1992 Moderator - Board of Deacons
1994 - 1996 Elder - Session
1996 President - Board of Trustees
1998 Chair - $1.5 Million Capital Campaign
Presentations and Publications:
' "Emerging Water Utility Trends" presented at the New Jersey Section - American Water
Works Association, March 2007.
"Effective Water Utility Management - Goals, Performance, Planning & Leadership"
presented at the New Jersey American Water Works Association Seminar, February
2007.
A "Challenges and Benefits of Total Water Management" Published in Underground
Infrastructure Management; November/December 2006.
"Challenges and Benefits of Total Water Management", Published in Journal of the
American Water Works Association; June 2006.
"A Paradigm Shift for Owners", Design-Build and the Water/Wastewater Sector: Risks
and Opportunities, Published in Design-Build DATELINE; January 2006.
"Emerging Water Utility Trends" presented at the Association of Metropolitan Water
Agencies, 2005 Annual Meeting; October 2005.
"American Waters Business Process Transformation: Enhancing Asset Management"
presented at the American Water Works Association, National Convention; June 2005.
A "High Performance Supply Chain" presented at the International Utilities and Energy
Conference -Barcelona, Spain; April 2005.
' "Affordability: An Industry Perspective" presented at the National Association of Water
Company Conference; October 2004.
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'. "Small Systems Affordability" presented at the National Association of Regulatory
Utility Commissioners (NARUC) Conference; February 2003.
A "Automation and Instrumentation, Making the Most of Technology in Our Operations"
presented for American Water Works Association teleconference; November 2000.
<& "The Future of Drinking Water Treatment" presented to the American Water Works
Association - Water Quality Technology Conference; November 1999.
A "Waste Stream Recycle" presented to U.S. EPA Stakeholders Meeting for Filter
Backwash Recycle Rule; July 1998.
& "Innovative Project Delivery Techniques" presented to the American Water System -
Annual Business Forum; April 1997.
A "Facility Reliability and Reserve Capacity" presented to the American Water System -
Annual Business Forum; May 1996.
& "Facility Automation" presented to the American Water System - Annual Business
Forum"; May 1995.
A "Source Remediation" presented to the American Water System - Annual Business
Forum"; May 1995.
4 "Industry Leadership through Participation in Water Industry Activities" presented to the
American Water System - Annual Business Forum; May 1994.
4 "Preparing a Request for Proposal" presented to the American Commonwealth
Management Service meeting; March 1990.
A "Using Technology as a Management Tool - Management through Facility Design"
presented at American Water System Management Seminar; May 1988.
4 "Process Selection for Arsenic Removal" presented to the Indiana Section - American
Waterworks Association; November 1987.
4 "Pilot Treatment Studies for the Kentucky River" presented to the Kentucky-Tennessee
Section - American Water Works Association; September 1987.
* "On-Line Instrumentation - Practical Consideration" presented to the New Jersey Section
- American Water Works Association; March 1986.
& "Pilot-Scale Investigation of Air Stripping for Removal of Volatile Organics" presented
to New Jersey Section - American Water Works Association; September 1981.
"Utilization of Belt Filter Press for Dewatering Water Treatment Plant Sludge" presented
to the New Jersey Section - American Water Works Association; September 1981.
-------
"Operating Experience with Granular Activated Carbon" presented to the New Jersey
Section - American Water Works Association; September 1979.
4 "Chloroform Formation in Public Water Supplies: A Case Study" presented to the 97th
Annual Convention of the American Water Works Association; May 1977. Published in
Journal of the American Water Works Association; February 1979.
"Adsorption of Alkyl Phenols by Activated Carbon"; Singer, Yen, Young; presented at
American Chemical Society -Division of Environmental Chemistry; September 1978.
"Adsorption of Phenolic Constituents of Coal Conversion Wastewaters"; Singer, Yen,
Young; presented at the Purdue Industrial Waste Conference; 1977.
Guest Lecturer: Johns Hopkins University: "Pilot Studies for Process Selection".
Rowan University: "Challenges in the Water Industry".
Lehigh University: "Water Treatment Process Selection Criteria"
Instructor: American Water System - Water Treatment Plant Design Course.
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Appendix II: Peer Reviewer Comments
-------
Peer Review of "Elevated Lead in D.C. Drinking Water - A Study of Potential Causative
Events"
REVIEWER COMMENTS
Reviewer #1
EPA Question Reviewer Comments
Reference
(Page in
Document)
General Comments
The organization of the chapters isn't clear to a reader. The report needs a roadmap, just a paragraph at
the end of chapter 1 that says LMP data will be presented and analyzed in Chapter 2, .... And the
evidence about all the causative factors will be evaluated and presented in Chapter 5 . . .etc.
The readability of the figures, when printed in black and white, is problematic in several cases, which I
will note below. The text should certainly omit references to the color of data symbols and lines. Even
in this era, it is too much to assume that all readers will view the report on their computers or have a
color copy available. Please review the figures in black and white and make the necessary adjustments.
Some are just fine, but others could be improved.
Much of the literature on the D.C. lead issue is in the gray literature and may not be available to many
readers. I include WQTC Proceedings, AwwaRF reports, reports to DCWASA and EPA and all the
internal DCWASA information. When these sources are used, it is important to include more
information about what the study entailed and what the results are. I will note instances where I think
more explanation is needed.
At several fairly key points in the presentation extensive lists of citations are given. In one case (p.48),
when I went to the papers that I could access (3 in journals. The other 7 in are in gray literature.) I
found that two of them had no data that supported the statement in the text. Please be sure that a
citation has specific information that supports a specific statement in the report.
Paragraph 2, line 2. The term "consecutive" system (also used in the Executive Summary) doesn't have
a common meaning to many readers. Either explain or just omit the word.
1st Paragraph 3 line 6 should change as to because
Last Paragraph line 2 add lead-tin before solder
Paragraph 2, Two issues with the causative mechanism
Paragraph 2, line 6 delete "major" before Pb (IV) solids. There weren't any others identified, or even
considered.
Last Paragraph, line 1 change became to were
Paragraph 1 The presence of brass and bronze fittings in the service connection and consumer
plumbing should be acknowledged.
Need to provide an overview of what is to come in the report.
Paragraph 2, line 1 should read "lead, copper and iron, using EPA
The reanalysis of the LCR reports is somewhat interesting, but not very important, since only the Jul-
Dec 1992 values change significantly. I would like to know if all sites were selected with lead service
lines, or if some had copper with lead-tin solder plumbing. A little more information about the
sampling protocol would be appreciated.
Same point as above. The detailed explanation of the small differences between the reported and the
reanalyzed results doesn't add much to the reader's understanding of the problem. Given the lack of
information about how DCWASA did their analysis, we can't even get insight into why the differences
occurred.
The pH story for the plants and the distribution system is complicated and important, regarding Pb (II)
solubilities. At this point, we can see that the pH at the entry points seems basically ok, considerably
above the allowable minimums in warm weather. The distribution system picture is less clear. It looks
like there are a few values below about 7.3, which really doesn't tell us much. However, when a much
larger data base is presented in Figure 28, it is clear that there was a much more prominent period of
low pH values that may have had a lot to do with Pb (II) solubility and high lead levels. It is too bad
that the initial data set misleads the reader. Perhaps words could be added that would make the reader
aware that the story is going to be more complicated and clearer about low pH values in the distribution
system.
Chapter 1
Page 1
Page 1
Page 1
Page 4
Page 4
Page 4
Page5
Page 6
Page 7
Page 8 & 9
Page 12
Page 13
Page 1 of 6
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Peer Review of "Elevated Lead in D.C. Drinking Water - A Study of Potential Causative
Events"
REVIEWER COMMENTS
Reviewer #1
EPA Question Reviewer Comments
General Comments (continued)
Figure 1. I suggest that the authors try using small symbols (x) with different shapes. The gray squares
form a band with little information discernable about the black diamonds (Dalecarlia plant) data.
Paragraph 1 last line. Please don't refer to the red line.
Figure 2. The figure seems to have several different data symbols, but there is no explanation about
what distinguishes them.
I know that the purpose of the report isn't to place blame for the crisis that the high lead levels created.
But the partial LSL replacement activities by DCWASA certainly has to rank high on a list of
ineffectual actions. I think the details on the number of partial and the number of complete
replacements should be incorporated into the report. Were lead profiles done at any houses where a
complete replacement was done?
Figure 7 solid line segments would be easier to see. ( as used in Figure 9)
Figure 1 1 The chlorine burn data are almost impossible to distinguish from the chloramine data.
It isn't clear to me why some of the profile results are discussed here and others in Chapter 5. In that
connection I don't see the relevance of the sentence about one home being sampled before and after
partial LSL replacement.
The point that LSLs are a primary source of lead is clear. However, I don't think the method of
subtracting the "background" sample values is justifiable. The lead in those samples surely comes from
the LSLs, too. If there are actual measures of lead in distribution main pipes (Keefer and Giani, 2005),
then those values could be used to indicate the contribution due to the mains. Please tell us what Keefer
and Giani measured.
The calculation of a percentage contribution to the lead concentration is hard to interpret, especially
since the overall average concentration isn't defined or presented. Figure 14 could be replaced by a
table with average concentrations for the 1st liter, for the rest of the premise plumbing, for the LSL and
for the main (based on samples from the mains). These values should be presented along with the
average volume of water in the first three categories, and the concentration and volume should be
multiplied to give the average contribution of lead from the three source areas for the lead profiles.
Standard deviations for concentrations, volumes and mass loadings should also be presented.
In calculating these concentrations and mass contributions, I think it would be justified to separate
samples collected during chloramination, from those affected by the chlorine burns and the
orthophosphate addition. It might be informative to present the average results for each of these
periods.
It should be pointed out that lead levels in quite a few samples of flowing water, originating upstream of
the LSLs, had lead concentrations consistently exceeding the action level. This indicates that for these
homes nearly all the water likely had high lead concentrations.
Section 4.2.3. It would be better just to present the concentrations in the source water and from
distribution main samples. The argument about diffusion and dissolution from LSLs should be in the
previous section, as an explanation for the anomalous values seen in the lead profiles and as a
justification for not subtracting the 0 or 00 lead levels.
Table 7. The statement about Giani, et al should be modified. "Large fractions of paniculate lead
occur in...
Figure 17. Several minor points. Could add dates of chlorine burn periods. If it is possible, it certainly
would be easier to read these figures with the x-axis labeled with simple dates, like 1/97, 7/97, 1/98,
7/98 etc. Trying to read the exact dates, see the very small (sometimes obscured) mark on the axis, and
figure out when something happened, is pretty difficult. The orthophosphate addition should be marked
with a horizontal arrow, like the other treatment changes.
Figure 21. It is stated that this house had a partial LSL replacement, but the volumes associated with
the LSL seem to change in the two profiles. What was going on?
Reference
(Page in
Document)
Page 14
Page 15
Page 15
Page 16
Page 20
Page 25
Page 29
Page 30
Page 36
Page 37
Page 43
Page 2 of 6
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Peer Review of "Elevated Lead in D.C. Drinking Water - A Study of Potential Causative
Events"
REVIEWER COMMENTS
Reviewer #1
EPA Question Reviewer Comments
General Comments (continued)
First paragraph. This discussion of ORP has the same problems that I discussed above. The measured
ORP is not a thermodynamic oxidation reduction potential in nearly every case because it responds to
all oxidation/reduction couples in a highly non-linear fashion, depending on how active each couple is
on the electrode surface.
Measured ORP levels need to be described more. Are these simply the recorded values? If so, tell us
what the reference electrode was. If they are corrected to the standard hydrogen electrode scale (EH),
then this needs to be stated.
Oxygen should be added to the list of water quality variables that affect measured ORP values.
Last paragraph. Schock, 2001 isn't in references. Do you mean Schock, et al. 2001? I read the three
papers that are in journals in this series often citations. Two of the three do not present evidence in
support of the statement that Pb (IV) is in scale on LSLs. Please review use of citations, so that cited
work has specific information that supports the specific statement in the text.
1st Paragraph, line 5. The statement that "Pb (IV) solids convert" is not clear. They must be reduced to
Pb (II) to become more soluble, and if they are reduced, then some other substance must be oxidized.
They hypothesis about causation has a significant gap.
2nd Paragraph. Line 6. Very little has been said previously about the role of high free chlorine residuals.
This probably is a good point, at least in that the higher chlorine dosages probably maintained chlorine
residuals into the service lines and consumer plumbing and provided enough oxidizing capacity to form
significant amounts of PbO2
Last Paragraph. Line 1 . The relation between free chlorine and measured ORP should be shown,
perhaps as a plot of free chlorine concentration vs. ORP. The logarithmic relation that is alluded to
actually would predict a very weak dependence of ORP on chlorine concentration over the range used
in D.C.
2nd Paragraph. 1st sentence. The sentence isn't clear. It can be improved some by saying "If an
orthophosphate inhibitor had been added", but the point about Pb (II) phosphate scales being protective
is a) either very obvious based on experience of many utilities orb) completely unknown if the authors
are thinking that free chlorine would still have oxidized Pb to form Pb (IV).
This paragraph is a very important summary of the hypothesized causation of high Pb levels. The roles
of free chlorine and low pH are very reasonable. There is a need for a mechanism of Pb (IV) reduction
and a statement that the lead levels found in the lead profiles are reasonably consistent with Pb (II)
solubility at pH between 7 and 7.5. The effort to make comparative statements about other systems are
less convincing. There is no data presented that relates to other systems' free chlorine or measured
ORP levels and the occurrence of Pb (IV). The purpose of the last two sentences isn't clear to me. The
last sentence makes it clear that DCWASA has a fairly low alkalinity, which has been stated before.
The preceding sentence may be intended to imply that maybe Pb (IV) is present in these field studies.
However, if it just a statement that many high alkalinity systems have lower lead levels that Pb (II)
solubility would indicate, that point probably isn't necessary.
2nd paragraph, line 6. The sentence seems to be an overstatement of what ORP measurements indicate.
I'd suggest saying. The transformation of existing Pb (II) to Pb (IV) is not well understood beyond the
presence and absence of free chlorine and the corresponding measured ORP values.
3rd paragraph. The second sentence could be restated: The solubility constants of PbO2, Pb3 (OH)
2(CO3)2 (hydrocerussite) and PbCO3 (10"66, 10"18 8 and 10"13, respectively) allow calculations that show
PbO2 is much less soluble than the Pb (II) solids.
4th paragraph. The observation by Schock and Giani that Pb (IV) solubility tends to decrease with
decreasing pH needs to be explained, since it certainly isn't the usual pattern for metal oxides. This is a
case of a significant observation from a non-accessible source needs some explanation so the reader can
understand why the authors are drawing their conclusion.
Reference
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Peer Review of "Elevated Lead in D.C. Drinking Water - A Study of Potential Causative
Events"
REVIEWER COMMENTS
Reviewer #1
EPA Question Reviewer Comments
General Comments (continued)
Last line. An explanation of what Schock and Giani did is needed, e.g. what minerals in the films, how
much of a pH change, etc.
3rd paragraph. The point about travel times in the distribution system hardly needs to be noted given the
scale of the Figure. You really couldn't see a delay of 2 or 3 days in the data in even if it were
uniformly present.
Regarding pH in distribution system. It appears that the much larger pH decreases in 2001 and 2002
correlate with lower alkalinities (I'm not real clear whether this is source water or finished water
alkalinity), but some discussion is needed of why the many low pH values were found.
2nd para. 3rd sentence. The sentence isn't clear. Does the last phrase mean that the solubility minimum
may be a pH values that are slightly acidic? If the details of the predicted solubility of Pb (IV) are
given, it may be very clear.
4 sentence. Schock 2004 isn't in references.
Line 6 change "appeared to be" to "was".
Omit references to blue and yellow lies in Figure 30.
Figure 30. I suggest including pH data even for the non-LCR monitoring periods, especially for July-
Dec. 2002. The correlation of pH and alkalinity (Figure 32) is important to see. Also, I think it would
be better it the lead values weren't connected with a line just use a nice, big symbol on the data point.
Figure 3 1 and Figure 33. These figures show almost nothing. We know that lead was higher post-
OCCT, but probably because chloramines were used and the pH was too low. We also know that lead
was lower pre-OCCT, but this is because the change to chloramines hadn't occurred. The correlations
show only that there is no correlation. It is misleading even to plot the lines.
1st paragraph. It is stated that isolated instances of nitrification were found, then it is said that
nitrification hasn't been documented. These contradict each other.
Figure 32. There is a floating piece of text (no data) that needs to be moved.
The issue of lead levels in the lead profile results from the mains are as discussed regarding p. 29. Lead
levels in samples nominally from the main that are consistently above 10 ug/L are pretty important.
Last Paragraph. The comparisons can and should be based on the amounts of lead contributed by the
three source areas, rather than on this computed concentration
Galvanic corrosion. The work done by Reiber and Dufresne needs more description of what they did
experimentally and what they measured. For example the flow direction in the pipes in Figure 34
should be indicated.
I recall that Marc Edwards talked about a different galvanic corrosion process, namely the deposition of
copper and the oxidation of lead, when part of a LSL was replaced with copper tubing. Should this
mechanism be discussed?
Grounding currents. Again, explanation of what Reiber and Dufresne did is needed to accept that there
was no impact on internal corrosion. Some explanation of why this conclusion is opposite the statement
in the first sentence, namely that currents have been implicated in metal release.
Reference
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Peer Review of "Elevated Lead in D.C. Drinking Water - A Study of Potential Causative
Events"
REVIEWER COMMENTS
Reviewer #1
EPA Question
Reviewer Comments
Reference
(Page in
Document)
Potential Causative Events
a) 1. Does the study consider potential
causative events that are appropriate?
a) 2. Are the causative events and
factors considered all relevant to the
purpose of the study?
a) 3. What additional causative events
or factors, if any, should be
considered?
This is the first occasion where ORP changes are invoked as
a causative factor. I'd like to raise several points that the
authors should consider. First, the thermodynamic oxidation
reduction potential is probably hardly changed at all when
free chlorine is replaced with chloramines. The EH values
computed for the pH, ammonia, chloride, and chlorine
concentrations are almost the same. The "oxidation state" of
the water really isn't different. Second, the measured ORP
reflects the contribution of all redox couples in the water,
with each having a thermodynamic potential and highly
variable reaction kinetics at the measuring electrode surface.
The differences in measured ORP values when chloramines
are used instead of chlorine reflect the kinetics of reaction of
chloramine at the surface, more so than a change in the
oxidation reduction potential. Thus, it seems likely that
chloramine isn't reactive enough to influence lead oxidation
very much. It is just good luck that chloramine also isn't
reactive enough to influence the measured ORP very much,
either. The argument should be restated to avoid the
implication that the oxidation potential is lower with
chloramine.
The evidence seems to clearly indicate that the LSLs
contained higher lead concentrations after the pH drop and
switch to chloramination. This leads us to think that PbO2
reduction must be a source of the lead. We can agree that
free chlorine can cause PbO2 to form and to keep it stable, but
what is reducing the PbO2 in the presence of chloramine?
This is a big hole in the argument about causation. There
doesn't seem to be any evidence that pertains to the
substance that is being oxidized when PbO2 is being
reduced.
Data Relevance
b) 1. Does the study consider each
causative event adequately?
b) 2. Is the data presented all relevant
to the purpose of the study?
No specific comments. See general comments.
No specific comments. See general comments.
Data Analyses and Conclusions
c) 1. Do the data and analyses support
the conclusions?
c) 2. Are there additional analyses that
could better support the conclusions?
c) 3. What additional conclusions, if
any, can be reached based on the data
and analyses?
The principal conclusions, that formation of PbO2 was
formed during use of free chlorine, that the change to
chloramine and reduction of allowable pH in the distribution
system, and that lead service lines are the predominant source
of the lead, are reasonable and plausible. The report also
does a good job of looking at a range of factors that do not
seem to have a major role.
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Peer Review of "Elevated Lead in D.C. Drinking Water - A Study of Potential Causative
Events"
Reviewer #1
REVIEWER COMMENTS
EPA Question
Reviewer Comments
Reference
(Page in
Document)
Follow-on Work
d) 1. Section 6 of the study identifies
possible follow-on work based on
available findings and conclusions
drawn from the study. Which, if any,
of the recommended follow-on work
should EPA undertake?
d) 2. What additional follow-on work
and/or research should EPA undertake
as a result of this study?
I like the idea of using a GIS system to look for correlations
in the data. However, it may well turn out that there really
isn't enough data to see strong relations and, further, that the
distribution of the LSLs in the system may obscure some
water quality or treatment correlations that may be important.
I also agree that more needs to be known about the impact of
orthophosphate in this complex system and that more
research is needed to really understand the mechanism of Pb
(IV) formation and reduction.
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Peer Review of "Elevated Lead in D.C. Drinking Water - A Study of Potential Causative
Events"
Reviewer #2
REVIEWER COMMENTS
EPA Question
Reviewer Response
Reference
(Page in
document)
General Comments
In terms of "simultaneous compliance" issues, additional discussion should
be included on the significant emphasis by DCWASA on "solving" TCR
related problems in the distribution system being a major factor in
subsequent decisions and events.
Figure 18. Check the Y-axis title (should it also state 90 percentile in
addition to average?).
Figure 19. The note stating "average (Pb) level before chloramines = 5
ug/L" is misleading since this only considers data from July 1997 to the
time of the conversion. The true "average" Pb level "before chloramines"
(i.e., considering all of the data) I suspect might be greater than 5 ppb.
Figure 18
Figure 19
Potential Causative Events
a) 1. Does the study consider
potential causative events that
are appropriate?
Yes.
a) 2. Are the causative events
and factors considered all
relevant to the purpose of the
study?
I would not consider "Lead Released from Piping Systems/Lead Service
Lines" (Sections 1.3.1 and 5.1) to be a causative factor in and of itself. For
example, if CCT had been optimized (before or after conversion to
chloramine), then lead release would not have happened on its own. I
would consider this a resultant outcome of the other causative
events/factors but not a contributing factor per se.
Sections 1.31
&5.1
a) 3. What additional
causative events or factors, if
any, should be considered?
My understanding is that WA made other treatment changes at or around
the time of chloramine conversion. One such change included the type of
alum used (from dry alum to liquid alum) and also attempts (over the years)
to gain better "control" of the aluminum coagulation process. Snoeyink
(2003) has noted possible protective or detrimental effects of aluminum-
containing scales on Pb release. Another treatment change was WA's
implementation of enhanced coagulation practices, which might be
associated with increased residual aluminum concentrations.
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Peer Review of "Elevated Lead in D.C. Drinking Water - A Study of Potential Causative
Events"
Reviewer #2
REVIEWER COMMENTS
EPA Question
Reviewer Response
Reference
(Page in
document)
Data Relevance
b) 1. Does the study consider
each causative event
adequately?
For "Lead Released from Lead Service Lines" (Section 1.3.1) the report
states "Given that many service lines in the DCWASA distribution system
are made of lead, this source is a major cause of high lead levels." Along
similar lines to the comment in (a) 2. above, the presence of (many or
some) lead service lines does not cause high lead levels.
Table 1 (Summary of Causative Factors for High Lead Levels) -1 would
disagree with the "medium" contribution assigned to this item. Based on
the data presented in the remainder of the report as well as "conventional"
Pb (II) theory, the improper corrosion control treatment in place prior to or
simultaneous with the conversion to chloramine is as "equal" a contributor
to the high lead levels seen after chloramine conversion. Had CCT been
optimized (e.g., using an orthophosphate inhibitor), it is unlikely that the
lead release would have been of the same magnitude. In fact, Section 5.3.2
states that the OCCT pH may have been "too low of a pH for maintaining
Pb (II) scales under chloramine conditions." The OCCT designated in
February 2000 and subsequent designation of OWQPs, and the OCCT
designated in May 2002 (retroactive to July 2000) were inappropriate.
Distribution System pH Levels and pH Variations (Section 1.3.3 and
elsewhere) - At a pH of 7.0, 90th percentile Pb levels should not have been
<15 ppb, in turn, raising a flag that the CCT mechanism wasn't what it
appeared to be. Such explanation as to how 90th Percentile Pb levels were
being maintained below the 15 ppb Action Level despite lower-than-
optimal pH for Pb (II) passivation might have led to awareness that other
factors needed to be considered related to the chloramine conversion. This
type of discussion should be included in this section as well as in related
paragraphs in Section 4 and highlighted as a "reality check" on theoretical
models. There is some discussion toward this end in Section 5.2.7 (4th
paragraph) but this linkage should also be carried into the sections
discussing (inadequate) pH levels.
Section 1.3.1
Section 5.3.2
Section 1.3.3
Section 5.2.7
b) 2. Is the data presented all
relevant to the purpose of the
study?
Chlorine burn data (e.g., Table 8 in Section 5.2.3) - discussion should be
added as to the likelihood (in theory) that Pb levels are/can be impacted in
the relatively brief time period of a C12 burn. What is the theory to explain
the kinetics/reaction rates for this? Perhaps this is an item to consider under
future research needs? Can, in theory, such a change affect Pb levels that
quickly? (one month)
Table 8,
Section 5.2.3
Data Analyses and Conclusions
c) 1. Do the data and analyses
support the conclusions?
Yes, with the exception of comments noted in (c) 3 below relative to the
"significance" of the inadequate (too low) pH.
Figure 19
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Peer Review of "Elevated Lead in D.C. Drinking Water - A Study of Potential Causative
Events"
REVIEWER COMMENTS
Reviewer #2
EPA Question
c) 2. Are there additional
analyses that could better
support the conclusions?
c) 3. What additional
conclusions, if any, can be
reached based on the data and
analyses?
Reviewer Response
Section 4.2.2 - Data for Pb at the "Point-of Entry" (POE) should be
presented and discussed rather than reliance on sampling from the
distribution system mains to infer POE levels. In addition, the report
defines "source water" as raw water from the Potomac River. This is
confusing with respect to conventional terminology used in the LCR and
various guidance documents in which a "source water sample" is defined as
"A sample collected at entry point(s) to the distribution system
representative of each source of supply after treatment."
Section 5.8 Drought Conditions and Effects on Corrosivity of DCWASA
Water - One consideration is whether drought conditions may have
affected the nature of the natural organic matter (NOM) in a manner than
affected the chlorine demand of the finished water, in turn affecting ORP,
etc.
As noted in Comment (b) 1, 1 disagree with the "medium" contribution
assigned to the "distribution system pH levels and pH variations" factor as
presented in the Table 1 (Summary of Causative Factors for High Lead
Levels). Based on the data presented in the remainder of the report as well
as "conventional" Pb (II) theory, the improper corrosion control treatment in
place prior to or simultaneous with the conversion to chloramine is as
"equal" a contributor to the high lead levels seen after chloramine
conversion.
Reference
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Section 4.2.2
Section 5. 8
Table 1
Follow-on Work
d) 1. Section 6 of the study
identifies possible follow-on
work based on available
findings and conclusions
drawn from the study.
Which, if any, of the
recommended follow-on
work should EPA undertake?
d) 2. What additional follow-
on work and/or research
should EPA undertake as a
result of this study?
Pb (IV) as a corrosion control treatment mechanism needs much greater
understanding and research, including under what conditions/factors does
Pb (IV) form, remain stable, etc. The effects of orthophosphate addition
under various ORP conditions are also important to understand (e.g., for
various system changes, can orthophosphate bind soluble lead to keep up
with the rate of Pb release from existing scales that may break down).
Fundamental research in Pb (IV) is needed. Some examples include:
defining threshold ORP levels to maintain protective scales; determining
the feasibility of converting Pb (IV) scales to some possible new Pb
orthophosphate compounds; etc.
As noted above, the impact of chlorine burn on Pb solubility (and reaction
kinetics thereof in short periods of time in which such switches generally
take place) would also be of significant interest to utilities.
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Peer Review of "Elevated Lead in D.C. Drinking Water - A Study of Potential Causative
Events"
Reviewer #3
REVIEWER COMMENTS
EPA Question
Reviewer Comment/Response
Reference
(Page in
document)
General Comments
Given the prevalence and importance of chloramination for many water
utilities, it is important that the casual reader does not directly link
chloramination with lead problems. While the Washington, DC lead
problems are an important "lesson learned", the Executive Summary and
Report should emphasis that the problem resulted from a "perfect storm"
(historical high chlorine dosage, presence of lead scales and lead service
lines, poor pH control, and chloramination). One or two of these
occurrences, in isolation, may not have resulted in the problem. The data
and conclusions presented in Section 5.2.6 should be emphasized and be
presented in the format that can be easily understood by the typically water
utility professional.
I also have a concern with how the sources of lead were characterized
between the faucet, in-house plumbing, lead service line and distribution
system (example p.29 and 30). While the text states that the lead service
lines were the primary source of lead and no or limited lead should be
present in the distribution system (water mains prior to meter and service
line), several of the figures do not support this conclusion. The engaged
reader should understand that the "distribution samples" are pulled through
the lead service lines and in-house plumbing, and are not indicative of
distribution system water quality. However, the casual reader might draw
the wrong conclusion. Therefore, I would consider either removing the
data from the graphs or footnoting why there was a presence of lead in the
distribution system samples. Question - Was any direct sampling/lead
analysis done from the distribution system during the study period? Also,
was only lead sampling done at locations without lead service lines?
Additionally, the author frequently reference that the lead service lines are
part of the distribution system (p.72 and other references). Most utilities do
not consider service lines part of the distribution system.
Section 5.2.6
Page 29 & 30
Page 72
Potential Causative Events
a) 1. Does the study consider
potential causative events that
are appropriate?
Yes. The study considers all of the classic causative events for lead
corrosion (pH, redox, temperature, etc) and adequately explains how these
events interact to cause the lead problems. However, given the variability
in pH, conductivity, temperature, total chlorine, etc., the reader is not
convinced that the original Optimal Corrosion Control Treatment (OCCT)
guidelines were correct. This issue is important because the study does not
establish that lead control was effective prior to the chloramine conversion.
In addition to the change in pH levels, the variability in other OCCT
parameters and lead sampling results suggest that lead control was
questionable even prior to the chloramine conversion. As shown in Figure
17, the set of the three data points (red triangles) with lead levels ranging
between 100 and 150 ug/L, on or before the conversion to chloramines,
indicate that lead control was already questionable prior to chloramine
conversion.
Page 1 of 5
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Peer Review of "Elevated Lead in D.C. Drinking Water - A Study of Potential Causative
Events"
Reviewer #3
REVIEWER COMMENTS
EPA Question
Reviewer Comment/Response
Reference
(Page in
document)
a) 1. continued
Also, the process for setting the current OCCT has not been described
(page 71) and it is not clear that the new parameters (when orthophosphate
is applied) are appropriate. Given the large variability seen in the water
quality parameters (page 13) it is not clear how the pH 7.7ฑ0.3 is
appropriate or will be consistently achieved.
Page 71
Page 13
a) 2. Are the causative events
and factors considered all
relevant to the purpose of the
study?
In general, yes. However, the potential causative effects parameters such
as conductivity and temperature need to have their role better described in
the report. For example, are these parameters important because they are
used in the calculation of corrosion indexes or impact lead solubility?
a) 3. What additional
causative events or factors, if
any, should be considered?
The study needs to de-emphasize individual causative factors and focus
more on the chain of events. A chart with a timeline dating back to 1990
would be useful to help understand the entire situation. Included in the
chart/timeline should be a description of key decisions, 90th percentile
lead levels, shifts in pH and chlorine, coliform events, and DBF values.
There is a need to place more emphasis on the fact that corrosion control
was an issue prior to the chloramine conversion and question whether the
OCCT/OWQP was appropriate. In the Appendix (pA-20) is a timeline of
the OCCT decisions. A better summary of the reasoning behind the
decisions would be helpful.
Page A-20
The decision to drop the allowable distribution system pH from 7.7 to 7.0
is not emphasized strongly enough as a causative factor. Running a
system at pH 7.0 with no phosphate and lead service lines is a poor
operating decision. Change in pH occurred in July 1, 2000. Conversion to
chloramines occurred November 2000. Average 1st draw lead samples
increased between December 1999 and November 2000. Second- draw
samples were greater than 15ppb in the July - September monitoring
period. It is unlikely that the change to chloramines could have
solubilized the lead (IV) so quickly. It may not be possible to ascertain
whether the change in pH directly resulted in lead release or if it affected
existing scales to allow the chloramine to solubilize the lead (IV).
Additionally, it is possible that drought conditions increased the levels of
sulfate and/or chlorine in the water. The lack of these data does not
exclude the role of the drought on lead corrosion. Potentially, chloride
and sulfate information from other nearby utilities (Fairfax) could be used
in this assessment.
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Peer Review of "Elevated Lead in D.C. Drinking Water - A Study of Potential Causative
Events"
Reviewer #3
REVIEWER COMMENTS
EPA Question
Reviewer Comment/Response
Reference
(Page in
document)
Data Relevance
b) 1. Does the study consider
each causative event
adequately?
In general, yes. However, as previously stated, more focus needs to be on
the pre-existing conditions prior to chloramination. Specifically more
emphasis needs to be placed on pH. For example, I believe that the
"Distribution system pH levels and pH variations" listed in Table 1 should
have a "High" rating for its "Relative Contribution to High Lead Levels'
especially since p.53 states, "varying ph levels can significantly affect the
formation of protective scales on the interior of the pipes and the capability
of the system to maintain those scales in a stable form".
Washington, DC had a unique combination of factors contributing to their
lead problems. USEPA allowed Washington, DC more flexibility in their
treatment during the 1990s than would be allowed by most States.
Appendix A summarizes the feasibility studies performed in 1998 to
analyze various post treatments schemes. While I believe it would be
difficult to include a statement in the Report, it would be interesting to
know whether it was an economic decision that led to the poor pH control
and lead corrosion prior to chloramination.
In the section on the sanitary surveys (p20) the last line states "it is unlikely
that findings from these sanitary surveys had any influence on tap lead
levels". However, only results from sanitary surveys from 1999 onward are
presented. A big question is - did earlier deficiencies lead to the coliform
issues which in turn led to the decision to go to higher chlorine levels? I
agree that it is unlikely that it was the prime causative event, but it may
have resulted in a cascade of events.
Table 1 &
Page 53
Appendix A
Page 20
b) 2. Is the data presented all
relevant to the purpose of the
study?
Yes. However, I would spend less time focusing on the "chlorine burn"
issue. See response to question c) 1.
SeeQ. c) 1.
Data Analyses and Conclusions
c) 1. Do the data and analyses
support the conclusions?
In general, yes. However, I have issues with the entire analyses associated
with the "chlorine burn". For example, the data in Figure 19 shows
considerable variability in monthly lead levels. Although the two dates
when the "chlorine burn" occurs show dips in average lead levels, there are
other examples of low average lead levels when chloramines were used
(Feb 03, Jan 04, Jul 04). This variability in lead levels makes it impossible
to conclude that the conversion back to chlorine had any statistically
significant reduction in lead. The dips in lead levels during the chlorine
burn are not distinguishable from the normal variability in lead levels.
Figure 19
Page 3 of 5
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Peer Review of "Elevated Lead in D.C. Drinking Water - A Study of Potential Causative
Events"
Reviewer #3
REVIEWER COMMENTS
EPA Question
Reviewer Comment/Response
Reference
(Page in
document)
c) 1. continued
On page 39, paragraph 4, there is no statistical analysis to suggest that 8 of
12 sites with elevated lead levels were different from 5 of 12 sites. On
page 40, the report suggests that a monthly average of 28 ug/L is different
from 17 ug/L which is different from 37 ug/L. However, the statistical
analysis provided does not support this statement. Application of a t-test
for these data is inaccurate since these are not paired data. A
nonparametric test (Wilcoxon) would be more appropriate. Given the
highly variable results for lead, it is not clear that these differences are
meaningful. If the data from the 4th High Pressure Zone was removed
(orthophosphate treatment) would the data have been more conclusive?
Page 39 & 40
As shown in Figure 21, if analytical inconsistencies could account for a
difference between 1 and 6 ug/L of lead, then how can the report conclude
that small variations between the "chlorine burn" and "chloramine" lead
data be significant. Again, interpretation of the data has been performed
using only "eyeball" statistics.
Figure 21
Finally, the term "chlorine burn" is poor and misleading.
c) 2. Are there additional
analyses that could better
support the conclusions?
The author might consider calculating various corrosion indexes under
variable water quality conditions in assessing the corrosion potential before
and after chloramine conversion.
c) 3. What additional
conclusions, if any, can be
reached based on the data and
analyses?
I believe the author reached many proper conclusions during his analysis of
the data. However, the Washington, DC lead occurrences must be put in
the proper prospective. The conclusions need to emphasize the pre-existing
conditions in the Washington, DC system prior to chloramination and the
other numerous factors that contributed to the lead problems post
chloramination. The author needs to continually emphasize that other
water utilities need to fully understand the combination of factors in the
Washington, DC system before relating this experience to the operation of
their system.
Follow-on Work
d) 1. Section 6 of the study
identifies possible follow-on
work based on available
findings and conclusions
drawn from the study.
Which, if any, of the
recommended follow-on
work should EPA undertake?
I believe the proposed DCWAS A-related follow on evaluation would have
limited value. It is general knowledge that lead service lines are a (the)
primary source of lead in drinking water. I am not convinced that the
proposed geographic information system work (GIS) to plot the sampling
data and other water quality characteristics in the distribution system
between before and after the LCR monitoring period will provide valuable
information. Given the variability in the water quality throughout the
distribution system and the variability of lead levels at individual sampling
locations, I am not convinced that any additional good correlation will be
derived. Also, if this study is performed, I am not also convinced that a
sophisticated GIS system is needed to complete the study.
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Peer Review of "Elevated Lead in D.C. Drinking Water - A Study of Potential Causative
Events"
REVIEWER COMMENTS
Reviewer #3
EPA Question
d) 2. What additional follow-
on work and/or research
should EPA undertake as a
result of this study?
Reviewer Comment/Response
There are several areas of follow-up work/research that might be valuable:
Additional research can be performed to define ORP conditions
under different chlorine and chloramination conditions/residuals.
For example, would lower free chlorine residuals in the
Washington, DC system reduce the Pb (IV) formation and the
problems with chloramine conversion?
Additional knowledge is needed on the impact the treatment
changes on scale formation and solubility of trivalent lead?
Utilities should develop a better understanding of the impact of lead
service lines replacement (especially partially replacement) on
compliance and lead levels. Specifically, is there any value in doing
partial lead service line replacement or would this action have a
tendency to negatively impact on compliance?
Research could be performed to determine the impact of meter life
on lead concentrations in drinking water.
Given the presence of paniculate lead in the Washington, DC
samples and the relatively small health effects associated with
particular lead, the overall importance of particular lead in the
regulatory compliance strategy should be investigated and possibly
reconsidered.
Reference
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