List of Tables Table 1. Wells Supplying the Lacey Water Department .............................................................................. 7 Table 2. Average Source Water Quality Results, 2011 and 2017-2018 ..................................................... 14 Table 3. Percent annual source production during distribution sampling May 2017 – April 2018 ........... 15 Table 4. Lead and Copper at Entry To Distribution .................................................................................... 16 Table 5. Distribution Taps: Ranges of Results from Samples Collected 2017-2018 .................................. 18 Table 6. 90th percentiles for Tap Samples Collected 2016-2017 ................................................................ 20 Table 7. Summary of LCR samples collected within the 188 pressure zone .............................................. 30 Table 8. Water quality in 188 PZ when 2011 LCR samples collected ......................................................... 31 Table 9. Schedule for Installing OCCT ........................................................................................................ 35
List of Figures Figure 1. Lacey Water System Schematic .................................................................................................... 8 Figure 2. Monthly source production during distribution sampling May 2017 – April 2018 .................... 15 Figure 3. pH Ranges at Distribution Tap Sites Sampled 2017-2018 ........................................................... 17 Figure 4. Customer Tap Sample Sites, 2016-2017 ..................................................................................... 19 Figure 5. Gallons pumped from sources in 2016- 2017 during Standard LCR tap sampling .................... 20 Figure 6. Theoretical Lead (cerussite) and Copper (malachite and cupric hydroxide) Solubility at Each Entry Point .................................................................................................................................................. 23 Figure 7a, 7b and 7c. Modeled Solubilities for Lead, Aged Copper and New Copper for source group ... 25 Figure 8. Expected pH at different blending levels near Source 6 (Judd Hill) ............................................ 28 Figures 9a and 9b. Maps of Hydraulic Modeling Under Summer Operation (9a left: Blending under Current Conditions; 9b right: Predicted areas above, and below pH 7 after Treatment Installation) ....... 29 Figure 10. Expected pH at different blending levels for McAllister (S20) and treated Madrona (S23/28) 32 Figure 11. Predicted pH with source treatment at S17, S01/S18, S23/S28 ............................................... 33 Figure 12. Flowchart for Evaluating Tap Monitoring Results ..................................................................... 38
Appendices A. 2017 Letter from DOH outlining CCT steps for Lacey B. Technical Memorandum from Confluence Engineering Group, LLC (2018): pH Treatment
Recommendations C. Source Entry Point Water Quality Data D. Distribution Tap Water Quality Data
City of Lacey 2018 Corrosion Control Evaluation
EXECUTIVE SUMMARY In 2018, the City of Lacey Water System, PWSID # 43500Y, completed a desktop corrosion control
evaluation of the water system that meets requirements for a large system that supplies a population
>50,000. The study was triggered following 2016-2017 sampling at residential taps, and while the lead
results were very low, they were not low enough to exempt the system from completing a corrosion
control study. Consequently, the Washington State Department of Health required that the system
conduct a corrosion control study and recommend treatment for optimizing the water system for corrosion
In recent years the Lacey water system has experienced a number of changes affecting water sources,
water conveyance and water treatment. This corrosion control study therefore represents water quality of
current sources supplying the system, as indicated by distribution tap samples collected for this study in
Solubility modeling was used to evaluate source and distribution tap data, and indicated that the water
system is nearly optimized for lead control. The system will be optimized for lead control by ensuring pH
≥7.0 within the distribution system. While action levels for copper are met which would suggest that the
system is optimized for copper control, copper release can be lowered further by increasing pH within the
system. Although raising pH is especially beneficial to control copper release from new copper surfaces,
cross-linked polyethylene has been the material of choice by builders for the last 10-15 years. Therefore,
corrosion control treatment will be optimized when pH in the water system is raised to pH ≥ 7.0.
To achieve this water treatment goal, Lacey is proposing to install three new pH adjustment treatment
facilities, at sources S17, S01/S18, and S23/S28 to increase entry point pH at these sources to pH 7.4.
All three are wellfield locations. Treatment will be installed in a stepwise manner, to coincide with
planned replacement wells to be constructed at sources S17 and S01. In addition, dosing of caustic soda
at the existing pH adjustment facility at source S04 was increased, to increase pH at the entry from pH 7.4
to 7.6. Sources that were not selected for treatment are small sources that blend in the distribution system
with non-corrosive or treated sources, or, in the case of Sources S24 and S25, are isolated within a
pressure zone that has met Action Levels since tap sampling began in 1995. Pre-design, design and
construction of the three new facilities will occur from 2019 – 2024.
Baseline monitoring in the distribution system will track pH in the distribution as the new treatment
facilities come on-online, with particular focus on monitoring within zones that blend with untreated
sources. In 2025, after the third treatment facility is constructed and is meeting stable entry point pH
levels, customer tap samples will be collected and distribution monitoring frequency will be increased.
Because the Lacey water system is complex and has multiple blending zones, a flow chart was developed
to help evaluate tap sampling results and to identify appropriate next steps based on the monitoring
The Action Plan for implementing optimal corrosion control treatment is based on meeting the
requirements of the current Lead and Copper Rule, but the City recognizes that the Federal Lead and
Copper Rule is under revision and the extent of revisions is unknown at this time. Portions of the Action
Plan may need to be revisited when the Lead and Copper Rule is revised.
City of Lacey 2018 Corrosion Control Evaluation
1.0 PROJECT BACKGROUND The Lacey Water System was regulated as a medium-sized system under the Federal Lead and Copper
Rule until 2010, when notified by the Washington State Department of Health (DOH) that the system
must complete the corrosion control requirements for a system serving >50,000 people. In December
2010, Lacey notified DOH of its intent to conduct a corrosion control study and complete subsequent
corrosion control treatment steps. At the time, Lacey was planning to construct a pH adjustment facility
for source S04 in 2011, and was anticipating that water purchased from the City of Olympia was going to
change from surface water to a groundwater source.
The final study report1 was completed and submitted to DOH in March 2014. The report included
distribution data collected after the source S04 pH adjustment facility became operational, and concluded
that the Lacey water system would be fully optimized when water from source S30 (intertie with the City
of Olympia) was treated to increase its pH, and when source S01 (an infrequently-used source) was
replaced. DOH approved the conclusions in the report in April 2014. However, by 2015 Lacey started
planning for inactivating the Olympia intertie as a permanent source, and met with DOH in early 2016 to
discuss remaining corrosion control steps. The parties agreed that Lacey could collect lead and copper
tap samples after the intertie was inactivated, to evaluate whether the Lacey system would now qualify for
the (b)(3) exemption2. Meeting the exemption would eliminate the need for completing the corrosion
control study. Tap samples were collected in 2016-2017, and whereas the results for lead were very low,
they did not meet the criteria for a (b)(3) exemption.
In February 2017 DOH provided notice to Lacey to complete a corrosion control study by August 2018.
The letter from DOH is attached as Appendix A. The expectation is for Lacey to collect additional
distribution and source samples to represent the current sources of supply to the system, to update the
analyses and recommend additional treatment to optimize the system for corrosion control.
Lacey contracted Confluence Engineering Group (“Confluence”) to analyze the updated data, make
treatment recommendations, and identify treatment goals for Lacey sources. These analyses and
recommendations are summarized in this updated report, and are based on a Technical Memorandum
from Confluence that is attached to this report (Appendix B).
1 City of Lacey Corrosion Control Evaluation Final Report March 2014 2 40 CFR 141.81(b)(3) states a water system is deemed to be optimized for corrosion control if results from two consecutive 6-month monitoring periods demonstrate that the difference between the 90th percentile tap water lead level and the highest source water lead concentration is < 0.005 mg/L.
City of Lacey 2018 Corrosion Control Evaluation
2.0 SYSTEM INFORMATION
The Lacey water system includes three treatment facilities (see Section 2.2), seven storage reservoirs, and
seven primary pressure zones and three sub-zones that serve clients at varying elevations. A schematic
showing the distribution system, major facilities and pressure zones is shown in Figure 1.
2.1 Water Sources The Lacey water system is completely self-supplied with 20 groundwater wells that are owned and
operated by the city (Table 1). Source S01, though, has been offline since 2016 and is planned to be
replaced in 2020. As shown on the Water Facilities Inventory (WFI), the system has 16 regulated sources
that include 12 individual wells and 4 wellfields (with two wells per wellfield). Sources that are regulated
as wellfields are noted in Table 1. All sources are approved for year-round supply.
Table 1. Wells Supplying the Lacey Water Department
DOH ID Source Name(s) Year Online Completed Depth (ft)
S01 Well 1 1965 122 Qga
S021 Well 2 1969 217 Qpg
S031 Well 3 1969 225 Qpg
S04 Well 4 1973 84 Qga
S06 Well 6C; Judd Hill 1993 385 Qpg/TQu
S07 Well 7 1976 479 TQu
S09 Well 9 1981 290 TQu
S10 Well 10 1981 212 Qpg
S152 Beachcrest well 1 1976 140 Qga
S162 Beachcrest well 2 1979 138 Qga
S193 Hawks Prairie Well 1 1994 646 TQu
S20 McAllister 1995 214 Qpg
S214 Madrona well 1 1997 329 Qpg
S224 Madrona well 2 1998 334 Qpg
S24 Nisqually Well 19A 1986 107 Qpg
S25 Nisqually Well 19C 1972 79 Qpg
S27 Evergreen Estates 2003 282 Qpg
S28 Madrona well 3 2004 330 Qpg
S29 Betti well 2005 390 Qpg
S313 Hawks Prairie Well 2 2013 656 TQu 1 Regulated as wellfield S18 by DOH 2 Regulated as wellfield S17 by DOH 3 Regulated as wellfield S32 by DOH 4 Regulated as wellfield S23 by DOH
City of Lacey 2018 Corrosion Control Evaluation
Figure 1. Lacey Water System Schematic
City of Lacey 2018 Corrosion Control Evaluation
City of Lacey 2018 Corrosion Control Evaluation
2.2 Source and Distribution System Treatment
Source treatment in the Lacey water system consists of three treatment facilities: a pH adjustment
facility, and two iron and manganese treatment facilities. In addition, a contact time chamber was
constructed at source S10. Water quality in the distribution system is maintained with system-wide
chlorination and a routine waterline flushing program. Treatment facilities and water quality programs
are described below.
2.2.1 pH Adjustment at Source S04 Although treatment was not triggered by source or tap sample results, Lacey’s comprehensive water
system plans recommended corrosion control at source S04 to address a history of corrosion of new
copper pipe in the vicinity of the well. The facility was constructed in 2012-2013.
The facility was designed to treat source water with 25% caustic soda (sodium hydroxide solution) to
achieve a target pH of 7.6 and alkalinity within 40-70 mg/L. Evaluations of water quality and treatment
alternatives for source S04 concluded that low pH was the primary factor affecting the corrosivity of the
water, and results from a relatively high concentration of dissolved carbon dioxide compared to nearby
sources S09 and S10 (HDR 2007). pH adjustment was determined to be more suitable for corrosion
control than calcium carbonate precipitation and corrosion inhibitor chemicals because well 4 supplies a
pressure zone that is fed by multiple wells, and will blend with other sources in the system that do not
need corrosion control treatment (HDR 2007). pH adjustment using caustic soda was the recommended
treatment for source S04 based on its ability to meet treatment goals along with its process flexibility,
lower capital cost and footprint, and simplicity of operation (HDR, 2007).
2.2.2 Iron and Manganese Treatment Facilities The city operates two iron and manganese treatment facilities. The first was a design-build ATEC facility
constructed at source S07 in 2001. The well 7 ATEC facility oxidizes iron and manganese with
potassium permanganate and 0.8% sodium hypochlorite prior to filtering through pyrolusite media. The
second facility, referred to as the Hawks Prairie Water Treatment Facility (HPWTF), was constructed at
source S19 in 2008 with capacity to also treat future source S31. The HPWTF oxidizes constituents in
raw S19/S31 water with air injection followed by 0.8% sodium hypochlorite injection. Then the water
containing the oxidants is filtered through manganese greensand before passing through a contact time
chamber to achieve breakpoint chlorination.
Both iron and manganese treatment facilities were designed to meet target finished water goals of <0.15
mg/L for iron, and <0.025 mg/L for manganese (<50% of the MCLs for iron and manganese).
2.2.3 Contact Time at S10 A contact time chamber at well 10 (S10) was installed in 2007, after numerous coliform-positive samples
occurred following a well rehabilitation project. The same 0.8% sodium hypochlorite solution used for
system disinfection is injected into raw water, which then passes through an underground contact time
chamber. Raw source water is sampled quarterly for bacteria, but coliforms have not been detected since
the contact time chamber was constructed. Since primary source disinfection is not required at this time,
contact time is provided but Lacey does not list this as a disinfected source.
2.2.4 System-wide Chlorination The Lacey water system has been chlorinated on a permanent basis since 2005. System-wide chlorination
was initiated after several non-acute total coliform violations occurred in 2004 – 2005. The violations
City of Lacey 2018 Corrosion Control Evaluation
were not attributed to source wells so 0.8% sodium hypochlorite is injected at all well sites for the
purpose of maintaining a disinfectant residual in the distribution system. Chlorination is intended to
achieve a target concentration of approximately 0.5 mg/L free chlorine in the distribution system,
although typically concentrations range from 0.4 – 0.8 mg/L.
2.2.5 Waterline Flushing Program The city started a routine unidirectional flushing (UDF) program in 2004. UDF systematically progresses
from source(s) to the periphery of the distribution system, and uses water valves to isolate and control
flow direction and velocities that scour the waterlines. The progression from source to periphery ensures
that “clean” water is used for flushing each section of pipe and that material cleaned from pipe walls is
discharged from the system to an appropriate discharge location.
Lacey’s UDF program was initiated to address frequent and extreme brown water events that could not be
controlled by spot flushing, and to prepare the distribution system for system-wide chlorination. The
initial two years of the program focused on removing legacy iron and manganese deposits, as well as
reducing biofilms containing iron and sulfur bacteria. The UDF program is now focused on preventing
brown water episodes by removing residual iron and manganese deposits, to raise chlorine residuals in
dead ends, and to manage iron and sulfur bacteria that are still present but are greatly inhibited by
chlorine and water treatment that reduces available food sources. Generally, the entire system is flushed
over a 3-5 year cycle although some areas of the system are flushed every 1-2 years. Lacey may expand
the program in the future to include service line flushing and targeted waterline swabbing.
2.3 Pipeline and Plumbing Materials Pipeline and plumbing materials provide the source of metals that can be leached into drinking water.
Materials can include copper, iron and galvanized metal used in piping; brass fixtures and fittings
containing lead, arsenic and/or zinc; and fluxes and solder used in both manufacture and installation of
2.3.1 Distribution Lines and Facilities Distribution lines
At the beginning of 2018, the distribution system consisted of approximately 2.1 million linear feet of
water main. The majority of pipe is six to twelve inches in diameter.
The approximate percentages of materials in the distribution system are as follows:
PVC or Polyethylene: 59.5 %
Lined Ductile Iron: 21.8%
Asbestos Cement: 16.8%
Other (includes concrete, galvanized metal, and “unknown”): 2%
Although asbestos cement can be vulnerable to corrosion, city staffs have observed that tree roots cause
the most damage to asbestos cement waterlines. Waterlines with a history of leaks and breaks are
identified for replacement through the city’s semi-annual waterline replacement program, and often
includes replacing some asbestos cement pipe. Operations and maintenance staffs have observed
evidence of corrosion in the water system such as tuberculated parts and fittings. However, many breaks
City of Lacey 2018 Corrosion Control Evaluation
and leaks are attributed to poor materials, such as bad gaskets or older non-standard valves and fittings, or
poor installation. Waterline corrosion has not been cited as a reason for waterline repairs or replacement.
Lead service lines have not been used in the Lacey Water system, and lead goosenecks have not been
found in older parts of the system that were constructed with non-standard materials. The Lacey water
system itself was created in 1968, well after lead goosenecks were commonly used, and the city’s
waterline replacement program has replaced waterlines and service connections from many of the
acquired water systems.
Water System Components
All new and replaced water system components meet NSF materials requirements and AWWA standards.
However, non-standard components such as fittings and valves were used in some water systems acquired
by the City of Lacey, particularly in the Huntamer’s Water System that became the Lacey Water System
in 1968. Lacey replaces non-standard materials when they are found during repairs or as part of waterline
The Reduction of Lead in Drinking Water Act took effect in January 2014 and requires all materials used
in water systems, brasses in particular, to be certified lead-free. This Act amended the Safe Drinking
Water Act to reduce the allowable lead content in all products in contact with drinking water from 8% to
a weighted average of 0.25% (using a wetted surface based averaging formula). The new lead-free
components are certified under NSF/ANSI Standard 372. The only allowable exceptions are for devices
associated with non-potable uses, such as toilets, tub fillers, shower valves, and service saddles. In
addition, fire hydrants and water main gate valves 2” or greater in diameter are exempt from meeting the
no-lead requirements. The intent of the Reduction of Lead in Drinking Water Act is to directly address
lead release into drinking water. Studies have shown that lead-free brass alloy components release
minimal amounts of lead and other metals compared to lead-containing components (Sandvig 2009).
Before January 2014, Lacey started transitioning to the new lead-free components as they became
Dezincification of brass fittings has been associated with lead release into drinking water and has caused
large failures in some water systems. Zhang and Edwards (2011) reported that use of dezincification-
resistant and low zinc brasses created a higher risk for lead release compared to brasses with higher zinc
content, especially if the low-zinc product was not also low-lead or lead-free. There are no indications
that dezincification has been a problem in the Lacey water system.
2.3.2 Home Plumbing In the Lacey water service area, materials used in home plumbing are predominately copper and cross
linked polyethylene (PEX), although galvanized pipe and PVC have also been used. Copper pipe was
used extensively in new construction in the 1980s and 1990s, but over the past fifteen years the use of
PEX for water plumbing has increased steadily and is now used in the construction of most commercial
buildings and subdivisions. At the time of the 2014 Corrosion Study, Lacey’s Building Official estimated
that PEX was used in at least 80% of new construction served by the Lacey water system. By 2018, PEX
is reported as the material of choice by contractors that construct the vast majority of new housing served
by the Lacey water system, and consequently is being used in almost all new residential construction
(Wade Duffy, Lacey Building Official, pers. comm.).
The city’s materials surveys have mainly focused on identifying single-family residences that qualify as
Tier One sites for residential lead and copper tap sampling under the current Lead and Copper Rule, i.e.,
residences constructed between 1983-1986 and with all (or mostly all) original plumbing. The original
City of Lacey 2018 Corrosion Control Evaluation
pool of Tier One homes used for tap sampling declined as older homes were renovated, or replaced, so in
2016 county parcel information was used to identify homes served by the water system that were
constructed between 1983-1986. During this construction period approximately 1,340 homes were built,
which represents <6% of the single family connections to the water system. This list was used to contact
residences for participating in tap sampling in 2016-2017; sampling results are summarized in Section
3.0 WATER QUALITY DATA This Section describes source (entry point) water quality and distribution system water quality from
samples collected for the 2014 Corrosion Control Study and this 2018 Corrosion Control Study Update.
Residential tap sample results for lead and copper results are also presented here.
3.1 Entry Point Source Water Quality For this updated corrosion control study, source samples were collected quarterly in 2017-2018 to
characterize water quality of sources currently supplying the Lacey water system. Changes in sources
since the 2014 study are the following:
Source S04 has been treated with caustic soda since 2013 to raise pH.
Source S30 (intertie with Olympia) was inactivated in 2016.
Source S01, identified in the 2014 study as a corrosive source, was offline during 2017-2018 due
to pumping issues and is anticipated to remain offline until it is replaced (planned for 2020). As
a result, this source was only sampled once for this study.
Source S31 was approved as a new source and was used in 2015-2016, but was offline from late
2016 through May 2018 due to sanding and mechanical issues. As a result, this source was not
sampled for this study but its construction report indicates water quality very similar to source
S19. Both sources are treated for iron and manganese at the Hawks Prairie Treatment Facility.
For this study, sources were sampled quarterly from July 2017 to April 2018. Data collection for this
study focused on parameters identified by DOH (Appendix A). Water samples were analyzed for
alkalinity, calcium, and sulfate; in addition, temperature, pH, specific conductance, and free and total
chlorine were measured in the field. Sources were also sampled quarterly in 2011 for the 2014 study. All
water quality results from 2011 and 2017-2018 are compiled in Appendix C. Average results are
summarized in Table 2.
Monthly water production from sources is summarized in Figure 2 for the period when water quality
samples were collected. Table 3 summarizes these data as percent annual production.
City of Lacey 2018 Corrosion Control Evaluation
Table 2. Average Source Water Quality Results, 2011 and 2017-2018
Appendix A – Blending Analysis .................................................................................................................. 23
Appendix B – Action Plan ............................................................................................................................ 23
Appendix C - Planning Level Cost Estimates for Caustic Soda pH Adjustment Facilities (RH2 Engineering) .................................................................................................................................................................... 23
The City of Lacey (City) contracted with Confluence Engineering Group, LLC to develop an optimal corrosion control plan for the City. The objective of this Task is to evaluate Lacey’s current water quality against the drinking water industry’s current understanding of optimal corrosion control and determine if adjustments are needed. The evaluation considered the following:
Current water quality and treatment conditions
Existing Lead and Copper Rule (LCR) requirements, which drive the basis for optimization recommendations in this report
Impacts of possible long-term revisions to the LCR (LT-LCR) and future optimization considerations
Key recent literature and generally accepted industry practices
Lead and copper solubility theory
According to City’s Water Resources staff:
Lacey’s service population increased above 50,000 people and therefore, the water system is now considered a large system under the LCR.
As a large system, the City must complete a corrosion control study and provide optimal corrosion control
Since the previous study (completed in 2014), the City has stopped purchasing water from the City of Olympia, which used to provide close to 30% of the total supply. Other changes include inactivation of Source 1 (Well 1) and addition of a new source (S31) in the Hawks Prairie wellfield. Well 1 is scheduled for replacement in the future. The City has also made upgrades that allow for expanded use of the Madrona wells (S21, S22, S28).
During 2016 and 2017, Lacey collected two standard monitoring sets of lead and copper tap samples with a goal to qualify for the “b(3)” exemption (40 CFR 141.81(b)(3)) that would have deemed the system optimized for corrosion control without further steps. The results from these two sets showed that the City continues to meet both action levels, but only met the “b(3)” 90th percentile Practical Quantitation Level criteria of 0.005 mg/L for lead in one of the two sample rounds (the 90th percentile lead levels for 2016 and 2017 were 0.006 mg/L and 0.005 mg/L, respectively). Therefore, this corrosion control evaluation was required and the City needs to have optimal water quality parameters assigned.
3. Literature Review
When the LCR was first promulgated in 1991, EPA established maximum contaminant level goals (MCLGs) of zero for lead and 1.3 mg/L for copper. While the rule has been revised several times and corrosion theory has evolved, these goals have not changed indicating them being adequately protective of public health. Significant changes in the corrosion theory relate to lead corrosion and optimal corrosion control treatment (OCCT). Advances have also been made in understanding factors impacting copper corrosion. Current industry knowledge of corrosion as it relates to the City’s water system is summarized below.
3.1. The Role of Scales
The scales that have formed on the pipe surfaces over time control the effectiveness of (and ability to optimize) corrosion control treatment. The scales can be complex, layered, and impacted by the water quality the pipe has been exposed to in the past. The scales are considered to be either passivating films that are formed when the pipe material and water react directly with each other, or deposits of precipitated or otherwise sorbed compounds (EPA 2016).
The characteristics of the scale and its structure determines how much metal could be released into the water. The most desirable conditions support the formation of insoluble and adherent scales such as lead and copper oxides. Soluble and less adherent scales tend to release more metals. Releases can also be expected with changing water quality conditions when the scales are trying to reach a new equilibrium.
Lead pipe scales are typically dominated by hydrocerussite (Pb(II)3(CO3)2(OH)2) or cerussite (Pb(II)CO3), which are both Pb(II) -carbonate compounds. Under highly oxidizing conditions, lead oxide, a Pb(IV)-compound, can form and become the dominant mineral. Copper-based scales are typically cuprite (Cu(I)2O), cupric hydroxide (Cu(II)(OH)2, tenorite (Cu(II)O), and malachite (Cu(II)2(OH)2CO3). When orthophosphate is used, these metals tend to form various phosphate scales (EPA 2016). The presence of other metals such as aluminum, iron or manganese, calcium, or organic matter will also influence the type and properties of the scales that form.
Solubility models predict the metal solubility from the scale in equilibrium with the water. It is important to note that theoretical models generally tend to over-predict soluble concentrations, and therefore, can be considered conservative. Because they do not predict absolute values, they should be used to evaluate likely trends in solubility, rather than actual metals concentrations presented on the y-axis. Additional limitations with use of theoretical models include:
Models assume conditions at equilibrium
o The time component to reach equilibrium under varying distribution system water quality conditions is not known.
o Frequent changes between significantly different source water qualities, such as low DIC surface waters and high DIC groundwaters, likely prevent equilibrium from being reached.
Models represent specific chemistry conditions
o Real world distribution system conditions vary considerably seasonally, spatially, etc.
o Models do not consider impacts of competing ions, or other chemical, physical, and microbial conditions that affect scale formation and stability in distribution systems.
Pb(II) and Cu(I/II) Solubility
Figure 1 shows the classical pH/alkalinity diagrams for lead and copper solubilities developed by Schock and Lytle (2011). These diagrams show lead and copper solubility as a function of pH and DIC, for a wide range of DIC conditions. These indicate that at pH of less than 8, increasing DIC generally lowers lead solubility, while around pH 8, lead solubility flattens out for some DIC conditions, and then there is a flip-flop, where increasing DIC causes increased lead solubility. Copper solubility tends to decrease with decreasing DIC at any pH level and generally with increasing pH.
Copper solubility and release due to uniform corrosion in the system is not only related to the water quality characteristics and conditions (pH, DIC, ORP), but also to the aging process of the pipe materials and scales. According to Schock and Lytle (2011), in the most ideal case, uniform corrosion of copper is
inhibited by the formation of a duplex film consisting of a layer of cuprite, Cu2O, underneath a layer of either tenorite or malachite. While these layers will theoretically form under equilibrium conditions, the process can take years, even decades, and includes intermediary steps with more or less stable and soluble compounds (such as cupric hydroxide solids (Schock and Lytle 2011)). More research is needed to understand the complex chemistry of aqueous copper and potential public health implications. As discussed below, revisions to the LCR may require additional sampling at newer copper installations. Although plumbing materials present in the City’s water system are at different stages of aging and experience different dominant scale types, a conservative approach for considering compliance with the LT-LCR would be to assume fresh copper surfaces and the presence of cupric hydroxide, the more soluble intermediate copper scale.
Figure 1. Lead and Copper Solubility as a Function of pH for Varying DIC (Schock and Lytle, 2011, and 2018 webinar)
A similar solubility evaluation approach was used to evaluate the corrosive tendencies of the City’s source waters. The theoretical lead and copper solubilities were modelled under current water quality conditions using WaterPro_6.30 and are discussed in Section 4.
3.2. Optimal Corrosion Control Treatment (OCCT) Strategies
The current industry understanding of OCCT for lead and copper control has advanced into the following:
1) Passivation through pH/alkalinity adjustment
2) Passivation through use of phosphate- or silicate-based inhibitors
3) Formation of a Pb(IV) scale through maintenance of a high free chlorine residual/high oxidation-
reduction potential (ORP)
These OCCT strategies are all based on controlling soluble lead and copper. However, optimal corrosion
control treatment can also reduce particulate lead to some degree when stable scales are formed and
maintained. Calcium carbonate precipitation is no longer a recommended treatment technology for lead
and copper control since it has been found to be non-uniform across plumbing surfaces. Additional
information on these treatment strategies is provided in Table 1.
Higher ORP, which is largely controlled by secondary disinfectant type and residual, impacts the formation
of lead (IV) scales, iron release, manganese release, and co-occurring lead present in iron and manganese-
rich scales. The role of microbial influenced corrosion can also be an important factor contributing to
metals release in distribution systems and premise plumbing (AWWA M58, 2017).
The lead and copper rule working group (LCRWG) has defined a range of water quality conditions that are considered corrosive to homes with new copper (Figure 2), since these conditions prevent passivation of new copper surfaces. Further or additional actions may be required when water quality falls within the shaded, corrosive area, as discussed in Section 5.
Figure 2. Conditions that are Corrosive to New Copper Surfaces as Defined by the Lead and Copper Rule Working Group (Roth et al., 2016)
3.3. Potential Long Term LCR Revisions (LT-LCR)
The LCR is undergoing revisions. In addition to potential changes to OCCT described above, other issues
with the current LCR may be addressed through the revision process. A series of stakeholder meetings
have been held over the past several years, and the following issues have been raised for consideration.
Some of these considerations are based directly on lessons learned from the developments in Flint,
EPA recognizes that the LCR is too complicated to comply with and enforce. A more prescriptive
regulation, with less discretion/judgment allotted to utilities and states is needed.
A more integrated approach to minimizing lead exposure is needed, considering contributions
from water, paint, soil, dust and other potential sources.
Proactive lead service line (including gooseneck) replacement programs may be required.
Clarifications of sampling requirements are needed, such as the recent directive prohibiting
flushing before stagnation period and use of narrow-mouthed bottles.
Need for increased optimal water quality parameter monitoring to verify process control.
Need to establish health-based, household action levels for lead.
Need for a health-based benchmark for lead (rather than action level) to communicate health risk.
Isolate and separate lead and copper issues.
Strengthen transparency and public education programs, particularly for at-risk populations.
Specific requirements and the degree to which the items listed above will be included the LT-LCR are currently uncertain. The release date for the draft LT-LCR has been delayed several times. The current projection is that a draft will be released for public comment in 2019.
Table 1 Overview of Corrosion Control Treatment Options (Source: Confluence Engineering Group Project Files)
Technique and Chemicals Used Benefits Challenges and Problems Calcium Carbonate Precipitation Potential (CCPP) Raise pH and adjust Calcium
Increase CCPP to 4-10 mg/L
Maintain positive Langelier Saturation Index.
Limited Poor/ineffective lead and copper corrosion control
Does not form uniform, non-porous passivated layer
Can have excessive precipitation and reduction in pipe capacities.
Raise pH and/or alkalinity
Various combinations of caustic soda, carbon dioxide, soda ash, sodium bicarbonate, and/or lime
Carbon dioxide stripping
Binds lead and copper by forming carbonate complexes
Suitable in lower-alkalinity water if adequate buffering capacity maintained
Creates beneficial pH conditions for stabilizing chloramine residual (where used)
Does not add nutrients to water
Can cause CCPP in hard waters (white precipitate)
Significant fluctuations in pH and DIC (e.g. surface water vs groundwater) can cause lead-carbonate to dissolve, porous scales, particulate lead
May require multiple chemical additions to hit specific pH/alkalinity/DIC targets in low alkalinity waters
Some alkalinity-adjustment chemical feed systems (solids/powders) can be difficult to operate
Phosphate addition (using zinc orthophosphate, phosphoric acid, or tripotassium phosphate)
Silicate addition (various percent concentrations and ratios)
Possibly requires only single chemical addition
Binds lead and copper by forming phosphate complexes
Possibly provides longer-lasting protection against intermittent fluctuations in treatment (e.g., blending with other waters, treatment interruption)
Effective over a range of water quality conditions
Polyphosphate is not effective for lead control
Silicate is very expensive and not used in larger applications
Silicates can raise pH of finished water
Orthophosphate effective over pH range 7.2-7.8
Increases downstream wastewater nutrient (and zinc, if used) loading
Nutrient loading may promote biofilm growth if disinfectant residual decreases, and will promote algae growth in exposed reservoirs
Insufficient dose can accelerate corrosion, and overdose can cause milky water
Nutrients may exacerbate microbially-influenced corrosion
Formation of Pb(IV) Scale
Use elevated free chlorine residual to favor formation of Pb(IV) scales
Pb (IV) scale is less soluble and more stable compared to Pb (II) scale formed under routine oxidation-reduction conditions
Can form increased disinfection by-products
Can result in increased customer taste and odor complaints
4. City of Lacey Water Quality Evaluation
4.1. Lead and Copper Tap Samples
The history of lead and copper tap sample results were characterized in the City’s 2014 Corrosion Study and updated through 2017. In general, copper levels have decreased and lead levels have remained low. Table 2 presents the 90th percentiles for the compliance sample sets for the Lacey main system (excluding historical results of any satellite system like Beachcrest that have since been consolidated into the main system).
Table 2. Lead and Copper Tap Sample Results
Year Number of
mg/L Lead mg/L Copper
1992 0.008 0.85
1995 0.003 0.70
1996 <0.002 0.50
1999 0.003 0.01 1.00 1.96
2002 0.008 0.012 0.92 1.8
2005 0.004 0.015 0.95 2.3
2008 0.008 0.010 0.96 1.4
2011 0.004 0.023 0.84 1.2
2014 0.006 0.011 0.86 1.2
2016 67 0.006 0.049 0.81 1.3
2017 63 0.005 0.019 0.69 1.1
Based on historical monitoring results, the system meets both action levels and therefore, by definition the City can be considered optimized for copper corrosion under the current rule and qualified for reduced monitoring. Yet the results show that copper levels are somewhat elevated, and if the LT-LCR were to separate copper sites from lead sites and require sampling from newer copper construction, further action to reduce copper corrosion may be required. Lead results are low indicating good lead control. In fact, the City failed to meet the “b(3)” definition of optimization by 0.001 mg/L in one of two full monitoring rounds (2016). Had the City met the b(3) criteria, no further treatment would be required for either lead or copper under the current LCR. However, if the future rule includes an individual household action level, further measures may be needed to address specific locations. The modeling scenarios in Section 4.2 help identify which wells would benefit most from additional treatment.
4.2. Solubility Modeling
The City has monitored water quality characteristics at entry points and at twelve sites in the distribution system on a quarterly basis in 2011 and approximately every two months starting July 2017. The medians of the available data at each entry point were used to evaluate the theoretical lead and copper solubility in thermodynamic equilibrium with the minerals predicted by the model (WaterPro_6.30) to be most prevalent in the scale. Table 3 summarizes the water quality for the currently active sources. Figure 3 shows the corresponding modeled lead and copper solubilities.
Because of the aging process of the copper scales, the modeling was completed for both cupric hydroxide (new surfaces) and malachite (aged surfaces). As shown in the figures, once malachite is formed, the copper solubility is significantly lower, and on the same scale as copper results measured by the City during LCR sampling. According to the City, the vast majority of copper within the City’s system is aged, since most new construction is using PEX plumbing, rather than copper plumbing materials. The dominant lead scale is predicted to be cerussite (Pb II) based on the water quality at the entry points. In areas where
chlorine residuals are typically greater than 0.8-1.0 mg/L, it is possible that plattnerite (Pb (IV)) could form, further lowering soluble lead levels.
Table 3. Summary of Water Quality Characteristics used for Solubility Modeling at Each Entry Point 1
S# Source Name mg/L s.u. mg/L as CaCO3 mg/L oC mg/L mg/L mg/L as C
S24 Nisqually 19a 69 7.10 55 37 11.8 6.0 4.0 16.1
S25 Nisqually 19c 70 6.93 59 36 11.5 6.0 3.0 18.5
S04 Well 4 96 7.38 72 42 12.9 0.0 11.0 19.1
S06 Well 6C; Judd Hill 93 6.89 76 47 12.3 6.0 12.0 24.4
S07 Well 7 102 7.43 83 52 11.1 8.0 12.0 21.9
S09 Well 9 59 7.66 43 25 11.2 7.0 6.0 10.9
S10 Well 10 83 7.51 64 47 11.3 7.0 11.0 16.7
S18 Well 2 & 3 100 6.89 82 52 12.6 6.0 7.0 26.2
S17 Beachcrest 132 6.99 98 80 12.1 10.0 10.0 29.9
S32 Hawks Prairie 57 7.61 40 21 11.5 8.5 2.0 10.2
S20 McAllister 97 6.98 67 55 11.5 7.0 8.0 20.5
S23 Madrona 1&2 92 6.98 66 54 14.2 7.0 8.0 19.9
S27 Evergreen 89 7.01 60 53 11.7 6.5 7.0 18.1
S28 Madrona 3 92 7.03 65 51 12.4 7.0 8.0 19.3
S29 Betti 181 7.15 140 116 11.8 23.0 10.0 39.8
1Median values were calculated from the available data (quarterly samples in 2011 and July – December 2017) for all other
parameters except the highest calcium concentration was selected as a more conservative measure.
Figure 3. Theoretical Lead (cerussite) and Copper (malachite and cupric hydroxide) Solubility at Each Entry Point
Based on solubility modeling (Figure 3), the most corrosive sources to fresh copper surfaces are S6, S17, and S18. To evaluate the impact of pH adjustment with caustic soda on lead and copper (new and aged)
solubilities, the wells were grouped into categories based on pH and DIC. pH and DIC are the controlling variables for corrosion control when using carbonate passivation. The ranges of water quality for these groups are presented in Table 4. The ranges of chemistry in the City’s sources, specifically pH and DIC, behave differently for lead versus copper as described in Section 3.1 and shown in Figure 4 (a-c). Lead solubility tends to decrease with increasing DIC and pH until about pH 8, while copper solubility tends to decrease with decreasing DIC and increasing pH.
Table 4. Source Grouping under Current Treatment Conditions
Figure 4(a). Modeled lead solubilities. Stars indicate the water quality groups; S1 represents water
quality from the currently inactive Well 1.
Figure 4 (b). Modeled copper solubilities in equilibrium with malachite (solid lines) and tenorite (dashed lines) representing aged surfaces and existing LCR. Blue line shows the copper action level.
Stars indicate the water quality groups; S1 represents water quality from the currently inactive Well 1.
Figure 4 (c). Modeled copper solubilities in equilibrium with cupric hydroxide representing new surfaces for potential LT-LCR . Blue line shows the copper action level. Stars indicate the water quality groups; S1 represents water quality from the currently inactive Well 1.
The results from the solubility modeling with regard to the existing LCR and potential future LT-LCR are summarized below.
1. Lead solubility (Figure 4a) is in good control for higher DIC wells as long as the pH is ≥ 7.0. Some additional benefit is obtained with increasing pH to 7.2, with only marginal benefit associated with raising the pH above 7.2. The exception is under low DIC conditions (≤ 10 mg/L C). The City’s sources with DIC of 10 mg/L C already have a median pH above 7.5 and are therefore optimized.
2. Aged copper surfaces (Figure 4b) show very low copper solubility with formation of malachite or tenorite. The City’s sources are optimized with regard to copper solubility under the existing LCR given compliance with the copper action level. However, marginal additional benefit could be realized by raising the pH ≥ 7.0, assuming some tenorite is present (dashed lines). If malachite (solid lines) is the dominant copper form in the scales, very little additional benefit is anticipated by raising the pH ≥ 7.0.
1. As shown in Figure 4c, solubility of new copper surfaces (cupric hydroxide equilibrium) is predicted to significantly decrease until approximately pH 7.2, after which the degree of benefit begins to taper off, up to a pH of approximately 8.0.
2. The sources with combined higher DIC and low pH are the most corrosive to new copper surfaces.
o Betti well (G5), with a DIC 40 mg/L as C and pH of 7.2, is corrosive to new copper surfaces due to its high DIC. Given the elevated hardness, it would be difficult to raise the pH further without causing significant calcium carbonate precipitation issues. Blending Betti water with either Hawks Prairie or Madrona will reduce the DIC and the corrosivity.
o The Group 4 wells (Sources 6, 17, and 18), with DIC of about 30 mg/L as C and pH of 6.9-7.0 are also corrosive to new copper surfaces.
o There are two Groups (#2 and #3) with DIC of approximately 20 mg/L C. Sources 4, 7, and 10 (Group 3) already have entry point pH’s around 7.4 and therefore, would not be considered significantly corrosive to new copper. The Group 2 wells have pH from 6.9-7.1 and are considerably more corrosive to new copper surfaces.
o Source 4 already has caustic soda addition in place and in the interim, increasing the level of treatment at this source to pH 7.6 would likely off-set the lower pH of several of the sources in the area (Sources 1, 18, and 6). The water quality from the other sources that also serve this area (Sources 9, 7, and 10) are considered non-corrosive.
o Source 1 was not included in the above analysis because it was offline during the 2017-2018 timeline. The City has now indicated that this well may be rehabilitated or replaced and brought back to service. According to the 2011 data and the one sample that was completed in 2017, this source has a finished water pH of 6.7 and DIC of 26 mg/L as C, which indicates highly corrosive characteristics to new copper surfaces.
4.3. Distribution System Water Quality
The City collects distribution system water quality parameter (WQP) samples from 12 sites covering all pressure zones. WQP sampling locations are shown as yellow triangles in Figure 5. City sources are shown as blue stars. LCR tap monitoring locations are shown as green and purple dots, with purple indicating a location with lead > 0.005 mg/L.
Figure 5. Water System Map. Location of sources (blue stars); WQP sampling sites (yellow triangles); LCR tap sample locations (green and purple dots).
Results from 2011, 2017, and 2018 sampling rounds are shown in Figure 6. The large pH increase between 2011 and 2017 is primarily due to discontinuation of the Olympia supply.
Figure 6. Median Distribution System pH (2011, 2017, and 2018)
The DIC in the distribution system (Figure 7) is mostly between 20-30 mg/L as C, consistent with the majority of City’s well supplies. The influence of low DIC Hawk’s Prairie Well can be seen on site 36 in the 400 zone, while the influence of the high DIC Betti Well is not noticeable in the medians of the data set.
Figure 7. Median Distribution System DIC (2011, 2017, and 2018)
5. Treatment Evaluation
The City’s water system is complex with multiple pressure zones and sources that draw from different aquifers and have variable water quality characteristics. The City’s LCR tap sample results indicate optimal conditions for copper under the existing LCR, and nearly optimal conditions for lead. Based on the 2017 supply records, about 34% of the total supply is already noncorrosive or does not require additional corrosion control treatment. Treatment recommendations summarized in this section consider this supply complexity, the likely level of improvement in water quality with additional treatment, spatial distribution
7 14 17 41 65 2 11 91 12 20 36 30 55 90
Sample Site2011 Median pH 2017 Median pH 2018 Median pH
337 Pressure Zone 400 Pressure Zone 188Zone
7 14 17 41 65 2 11 91 12 20 36 30 55 90
2011 Median 2017 Median 2018 Median
400 Pressure Zone337 Pressure Zone 188Zone
of the wells, blending of wells, and future plans for additional supply and investments. It is not feasible or likely necessary to treat all active sources that might be corrosive to new copper surfaces when some sources serve built-out areas that are not zoned for new construction. Furthermore, according to the City’s Building Official, PEX started being used in the later 1990’s, and has been used in the majority of homes starting in 2005. It is now used almost exclusively in large developments. Therefore, the recommended approach includes prioritized and step-wise improvements that focus on optimizing corrosion control treatment to maximize public health protection associated with potential lead release, while also considering the need for enhanced copper control under a future, more stringent LT-LCR.
5.1. Point of Entry Optimal Water Quality Parameters (OWQPs) – Existing LCR
For the water quality characteristics of the City’s supply portfolio, optimal corrosion control treatment for the existing LCR is achieved at pH ≥ 7.0. Given the complexity of the City’s system and significant blending between sources, within reservoirs, and across pressure zones, not all sources will need treatment to reach pH ≥ 7.0 within the distribution system. pH ≥ 7.4 should be targeted for sources with existing treatment, those selected for future treatment, and any new wells that are brought on line in the future. Specific treatment recommendations are summarized below. Once treatment is installed as summarized below, the City’s portfolio of non-corrosive sources will increase from approximately 34% to approximately 84% of pumped capacity.
1. Increase the caustic feed to raise pH at Well 4 to 7.6. The treatment facility was sized for a larger supply capacity than currently available at the site. The City should also add supply capacity at this site to fully utilize the existing treatment.
2. Install pH adjustment treatment to increase the entry point pH to 7.4-7.6 at the following sources:
a. G2 Wells: i. Madrona Wells 1, 2, and 3 (S23 and S28). As large capacity wells, this would
benefit the 400 and 337 zones, and under some operating schemes, the 188 zone.
ii. Evergreen Estates (S27) to address the areas of new growth that may include newer copper plumbing and typical winter operating conditions.
b. G4 Wells: i. S18 in conjunction with replacing Well 1 (S1) which would result in pH increase
in 337 zone. ii. S17 in conjunction with replacement of one of the Beachcrest wells.
5.2. Point of Entry OWQPs – Future LT-LCR
The future LT-LCR may require sampling from homes with newer copper plumbing. As shown in Figure 8, raising the pH of Groups 2 and 4, as proposed above, would also shift these sources into the “noncorrosive” zone for new copper surfaces.
Figure 8. Impact of Increasing pH of G2 and G4 Wells on Copper Corrosion
5.3. Distribution System OWQPs – Existing LCR
Some degree of blending will occur within the distribution system, raising the pH of a significant portion of the remaining 16% of untreated sources. A detailed blending analysis was conducted and results are shown in Appendix A, and used to support the recommendations below.
Key WQP recommendations for distribution system sites under the existing LCR include:
1. The pH within portions of the distribution system that serve Tier 1 homes (potentially containing leaded materials) should be maintained ≥ 7.0.
2. A few small areas will likely continue to receive untreated water. The City will attempt to minimize these areas over time through:
a. Operational modifications to enhance blending, b. Preferential source use, c. Increasing entry point pH for large producers (such as Madrona Wells), or d. Confirming through special monitoring and plumbing investigations that lead and
copper levels are below action levels (i.e., Hot Spot analysis).
Given the complexity of the system, a set of WQP Bins have been developed to visualize and track the anticipated impacts of treatment and blending, as shown in Figure 9. The overarching objective is to meet Bins 1 and 2, since they were developed to ensure optimal lead corrosion control, and should be beneficial under the existing and future LT-LCR.
An Action Plan (Appendix B) has been developed to describe water quality monitoring (including routine and investigative monitoring) that will help to understand the impact from each source and installed treatment over time. This information will be used by the City to determine if:
Optimization has been reached
Treatment at additional sources or modifications to existing treatment is needed, or
If other operational strategies should be implemented to ensure optimization under the current and future LT-LCR.
The Action Plan may need to be modified once the LT-LCR is published and in effect.
Figure 9. Anticipated WQP Bins after Treatment Installation at S23&28, S18, S1, S17, and S27. (Note: if S27 is not treated, Bin 3 will also include areas that receive ≥ 50% S27).
5.4. Distribution System OWQPs – Future LT-LCR
1. The pH within portions of the distribution system that serve Tier 1 homes (potentially containing leaded materials) should be maintained ≥ 7.0.
2. The pH within the portions of the distribution system that are expanding and may have homes with newer copper plumbing should be maintained at ≥ 7.2. These areas should be identified through review of construction records combined with WQP monitoring after recommended treatments discussed in Section 5.1 are operational, in accordance with the City’s LCR Action Plan.
5.5. Chemical Selection and Dosing
Based on the EPA Revised Corrosion Control Treatment Guidance Manual (USEPA, 2016), the recommended treatment for reducing copper corrosion for source with pH less than 7.2 and DIC of 5-35 mg/L as C is to raise pH using potash, caustic soda, silicates, or aeration. Table 5 provides a summary of potential treatment strategies for all untreated sources (including increased caustic soda dosage at Well 4). Planning level cost estimates for treatment using caustic soda have been developed and are summarized in Appendix C. Cost estimates for soda ash and aeration are under development.
The City has caustic soda treatment in place at S04 and is familiar with its use. Caustic soda would not significantly increase the alkalinity of the already fairly high alkalinity sources and would be relatively easy to adjust to different treatment end points. However, caustic is a hazardous chemical requiring safety measures in the treatment plant to prevent exposure (operators) and accidental overfeed. The estimated
dose to reach pH 7.4 and the maximum dose to avoid undesirable carbonate precipitation in the distribution system are presented in Table 5.
Aeration is typically the most appropriate strategy for higher DIC wells such as in the City’s Group 4 wells. The level of aeration needed to achieve the desired entry point pH was estimated for all the corrosive supplies using chemical equilibrium modeling (Table 5). Aeration would need to strip 60-70% of the carbon dioxide to reach pH of 7.4. Efficient aeration processes such as packed towers often require breaking head and repumping making aeration less cost-effective compared caustic soda based on capitol costs. However, the major advantage of aeration is the lack of chemicals and potentially lower lifecycle O&M costs. There is also less flexibility to meet different pH endpoints with an aeration system as it cannot be easily adjusted. Furthermore, it may not be possible to actually reach the “upper limits” using an aeration approach. This would need to be confirmed through piloting and/or additional modeling, communication with vendors, etc.
Adding orthophosphate would not be an option unless implemented system-wide which would mean also treating the sources that are not considered corrosive to lead or copper. Furthermore, orthophosphates are most effective in the pH range 7.2-7.8, so pH adjustment would be required anyway. Therefore, orthophosphate treatment was not considered cost effective or advisable for the City.
Because the wells have adequate alkalinity, use of soda ash or potash are not needed, but could be used in lieu of caustic soda. Soda ash dose and performance were evaluated and the estimated doses for cost planning purposes are also included in the Table 5. Soda ash doses are higher than the caustic doses due to the increases in alkalinity. Soda ash would likely be brought to site in powder format.
Table 5. Summary of Modeled Treatment Options for the City’s Sources
1As 100% NaOH or Soda Ash 2Expected capacity after replacement 3Upper pH limit to avoid calcium carbonate precipitation
Increasing the system pH may increase the formation of trihalomethanes (THMs), although the groundwater is typically low in organic carbon and results from the City’s 2017 Water Quality Report indicate that the maximum result obtained was 10 ppb. Therefore, the proposed increase in pH is not anticipated to result in a regulatory concern due to increased THM formation.
Increasing the pH in range of 7.4-7.6 improves chemical stability of legacy iron and manganese in the distribution and provides an environment of lower metal solubility in general. In addition, pipe scales are more stable with smaller swings in the pH and more stable water quality conditions in the distribution.
The City receives occasional inquiries regarding very hard to remove scales on fixtures, shower stalls, etc. Since these deposits cannot be removed with acidic products, it is very likely that they are silica-based deposits. Several of the City’s wells have silica levels that could be considered problematic in terms of causing evaporative spotting and accumulation. Raising the pH will not impact the behavior of silica in the City’s distribution system, unless the pH is raised to > 9.5, the point at which silica precipitation can begin to occur.
Should the City increase chlorine levels to reduce iron release from pipes or for other reasons, a resultant increase in ORP will occur, which can be beneficial especially for lead control. Under highly oxidizing conditions, Pb(IV) scales may form which are very stable and less soluble than the Pb(II) carbonate-based scales, which are presumed to dominate under current pH, ORP, and DIC conditions.
6. Summary of Findings and Recommendations
1) Lead solubility is in good control in the City’s system, and is nearly optimized, as demonstrated by compliance monitoring results. However, some minor additional benefit could be realized by raising the pH to ≥ 7.0 in areas with Tier 1 homes, likely allowing the City to meet the b(3) criteria definition of optimization, and assisting with compliance with a future, more stringent LT-LCR.
2) The City meets the copper action level and is optimized for copper under the existing LCR. Copper solubility is in good control for aged surfaces dominated by malachite or tenorite.
3) Several of the City’s sources have water quality that is considered corrosive to new copper surfaces. The sources with combined higher DIC and low pH are the most corrosive to new copper surfaces, and could require treatment under the LT-LCR.
4) Given the complexity of the City’s system and significant blending between sources, pH ≥ 7.4 should be targeted for sources with existing treatment, those selected for future treatment, and any new wells that are brought on line in the future.
5) For the water quality characteristics of the City’s supply portfolio: a) Optimal corrosion control treatment for the existing LCR is achieved at pH ≥ 7.0. b) Optimal corrosion control treatment for the potential LT-LCR is achieved at pH ≥ 7.2 for
new copper surfaces. This should be revisited based on the final, published LT-LCR. c) Treatment of selected sources to pH ≥ 7.4 will help maintain these water quality goals
throughout the vast majority of the distribution system, under the existing and future LT-LCR.
6) It is not feasible or necessary to treat all the sources in the City’s system considering that not all of them are of significant capacity or supplying homes that are at risk of copper or lead corrosion.
7) The risk assessment, source capacity, blending analysis, and potential impacts to overall distribution system water quality led to the following recommendations which will increase the pH to ≥ 7.4 in more than 84% of the City’s pumped capacity entering the distribution system.
a) Increase the caustic feed to raise the pH at Well 4 to 7.6. b) Install pH adjustment treatment to increase the entry point pH to 7.4-7.6 at the
following sources: i. S23 and S28
ii. S17 in conjunction with replacement of one of the Beachcrest wells that will also increase the source’s capacity.
iii. S18 in conjunction with replacing Well 1 (S1). iv. S27 as the major winter supply source.
8) After treatment is installed, evaluate remaining areas of higher risk for lead and copper corrosion separately as summarized in Appendix B – Action Plan. The Action Plan should be used to help the City determine when the system has reached optimal corrosion control. The Action Plan is based primarily on the existing LCR, but should nonetheless be beneficial towards compliance with a future, more stringent LT-LCR. However, action triggers may need to be modified depending on final LT-LCR revisions.
AWWA, 2017, Internal Corrosion Control in Water Distribution Systems, Manual of Water Supply Practices M58, 2nd edition.
AWWA Webinar: Lead and Copper Corrosion 101: Principles and Guidance, January 17, 2018, Darren Lytle and Michael Schock, USEPA
Roth. D.R, Cornwell, D.A., Brown, R.A. and Via, S.H,. 2016, Copper Corrosion Under the Lead and Copper Tule Long-Term Revisions. Journal AWWA, 108:4 April.
Schock, M.R and Lytle, D.A. 2011. “Internal Corrosion and Deposition Control”. Water Quality and Treatment: A Handbook of Drinking Water, 6th ed., New York: McGraw-Hill
USEPA, 2016. Optimal Corrosion Control Treatment Evaluation Technical Recommendations for Primacy
Agencies and Public Water Systems. EPA 816-B-16-003. March 2016.
Appendix A – Blending Analysis
Appendix B – Action Plan
Appendix C - Planning Level Cost Estimates for Caustic Soda pH Adjustment Facilities (RH2 Engineering)
APPENDIX A - BLENDING ANALYSIS
Blending analyses were completed for the areas that will receive water from sources that were not prioritized for treatment. This includes S06 – Judd Hill, S20 - McAllister, and S24/25 - Nisqually. The goal of the analyses was to evaluate the expected water pH in the distribution system within the zone of influence of these sources after blending with treated sources.
S06 Judd Hill Area
S06, Judd Hill, is a relatively small source. Its total contribution to the City’s supply portfolio was 3-4% in 2016-2017 and increased use is not planned. S06 will blend to some degree with water from S07 (Well 7) and S18 (wellfield for Wells 2 and 3) in the distribution system. Results of the analysis are shown in Figure 1. Assuming treated sources are treated to pH 7.4, pH 7.0 (Bin 2) can be reached once the blend fraction decreases below 75% Judd Hill water (e.g., at least 25% Well 7/S18 water). pH 7.2 (Bin 3) can be reached only when 25% of the blend is Judd Hill water and at least 75% of the water in the distribution system is from Well 7 or treated S18. Increasing the S18 entry point pH to 7.6 will reduce the amount of S18 water needed to reach pH 7.2 (Bin 3) down to 50%.
Figure 1. Expected pH at different blending levels near Source 6 (Judd Hill).
Nisqually (S24/24), 188 Zone
The 188 zone is supplied by Sources 24 and 25 and can receive some water from the 400 zone through
the Nisqually PRV. According to the City, Madrona and Betti wells would be the main sources supplying
this PRV and consequently, the 188 zone, when the PRV is operational. The blending analysis was
completed with the larger of the Nisqually sources, S25 (the Nisqually wells have very similar water
quality). Figure 2 shows the modeled pH in the distribution system when blending S25 with Betti or
treated Madrona water. To provide a minimum pH of 7.2, no more than 40% Nisqually water can be in
the blend (need at least 60% treated Madrona water at pH 7.4). However, Nisqually is a non-expanding
portion of the system, and new copper plumbing is not anticipated in this region. There are a few homes
that meet Tier 1 construction dates, so lead solder may be present. Thus, the target of the blending
analysis is to meet a minimum pH of 7.0. This can be met if the water in the distribution system has at
least 25% of the other supplies, that is, no more than 75% Nisqually water.
Increasing the treatment at Madrona to a higher entry point pH would lower the needed blending level
to meet the various pH targets. The average pH of Betti well is 7.15 and therefore, blended water pH
would not go above pH 7.2 to meet Bin 3, but will meet Bin 2 (pH ≥ 7).
Figure 2. Expected pH at different blending levels in the 188 Zone around Source 25 (Nisqually 19C).
McAllister (S20) and Evergreen Estates (S27), 337 Zone
Both McAllister (S20) and Evergreen Estates (S27) have been significant supplies for the City representing 10% and 16% of the total volume pumped in 2016 and 2017, respectively. S27 is also a priority well to meet winter demand. These sources typically serve the south 400-pressure zone where there are no Tier 1 homes and the southwest portion of the 337 zone (through PRVs).
Both of these areas have experienced growth and are still growing making them at higher risk for copper corrosion. All new development is using PEX-piping, but there is a large development with copper piping (no lead) near S27. To address this, the City is planning to install treatment at S27, after the other priority treatments have been completed. S27 was prioritized for treatment over S20 because of its larger water right and the plan is to blend S20 with treated S27 when the S20 is in use. As shown in Figure 3, the blending analyses indicates that if Evergreen is treated to pH 7.6, 50% blending level would be needed to maintain a minimum pH of 7.2 (Bin 3). To meet the Bin 2 criteria (maintain pH ≥ 7.0), the proportion of S20 in the overall supply can increase to greater than 90%.
Figure 3. Expected pH at different blending levels for McAllister (S20) with treated Evergreen Estates (S27)
Figure 4 shows the modeled distribution water pH when McAllister (S20) mixes with treated Madrona water. Having more than 40% of S20 supply will drop the distribution water pH below 7.2 (Bin 3), unless Madrona is treated to a minimum pH of 7.6. In this case, up to 50% S20 water can be in the blend while meeting Bin 3 criteria (maintain pH ≥ 7.2). To meet the Bin 2 criteria (maintain pH ≥ 7.0), the proportion of S20 in the overall supply can increase to greater than 90%.
Figure 4. Expected pH at different blending levels for McAllister (S20) and treated Madrona (S23/28)
The SW 337 zone has several Tier 1 homes. In the distribution system, the water from S20 and S27 may blend with each other, Madrona, or, if the PRV(s) are open to the 337 Zone, the sources supplying the Steilacoom and Union Mill reservoirs. The sources that feed these major reservoirs in the 337 zone include Sources 4, 7, 18, 9, and 10. Source 6 is not large enough in capacity to reach the reservoirs.
To estimate the water quality in the Steilacoom and Union Mill reservoirs, a hypothetical blend of the sources supplying that reservoirs was created. The blended portions of the sources were based on average volume pumped from each source in 2016 and 2017. This was considered to be more representative of the stored water than using the individual pumping capacities of the wells. Table 1 presents the blended water quality and the proportion of each source used to create the blend. Adding treatment to S18 has a significant overall impact on the pH of the reservoir water in the 400 zone. The increased treatment at S04 slightly increased the blended water pH in the reservoir, but did not change the overall blended water characteristics. Increasing the pH of S27 to a minimum of 7.4 will be compatible with the anticipated chemistry in the blending zones.
Table 1. Estimated water quality in Steilacoom and Union Mill Reservoirs based on supply blending
Source # S04 S07 S09 S10 S18
Proportion of the blend1 11.3% 32.1% 3.0% 27.2% 26.4%
Pump capacity (gpm) 750 1,800 650 1,000 830
Water Quality / Treatment Condition
Alkalinity mg/L as CaCO3
DIC mg/L as C
Current Reservoir Water
49 21.0 Reservoir Water after S18 Treated to pH 7.4
Reservoir Water after S04 Treated to pH 7.6 and S18 Treated to pH 7.4
1 based on total gallons of water pumped from these sources in 2016 and 2017.
However, since treatment installation at S27 could take several years, Figure 5 was created to show impacts of untreated Evergreen Estates (S27) water blending with treated Madrona water and also with Steilacoom Reservoir water within the 337 zone. Greater than 90% untreated S27 water can be accommodated in the blend while still maintaining pH ≥ 7.0 (Bin 2).
Figure 5. Expected pH at different blending levels of S27 and Other 337 Zone Blended Supplies.
APPENDIX B - ACTION PLAN STEPS TO REACH OCCT
Due to the complexity of the City’s water system with multiple sources, treatments, water quality characteristics of supplies, and vintage of the homes, there is no simple solution for system-wide optimal corrosion control. The approach laid out in the corrosion control optimization report prioritized treatment installations to the largest, most corrosive sources that will have the most significant impact in the overall system. Additionally, the treatment locations were prioritized to target location of Tier 1 homes receiving water from untreated sources with corrosive water quality. To confirm and evaluate the level of optimization in the City’s water system, the following steps are proposed:
1) Conduct WQP monitoring to determine baseline conditions throughout the system, especially in
areas of highest concern including:
a) Quarterly monitoring for pH, temperature, alkalinity, and conductivity (for source tracing)
b) Add locations in the blending zones receiving water from untreated, potentially corrosive,
i) Nisqually – due to potential Tier 1 homes, but non-expanding so no new copper
ii) Judd Hill – Adequate blending during summer when metals release is highest, but potential
hot spot during winter conditions, some Tier 1 era homes
iii) S20 service area – Blending zone with Madrona
iv) S27 service area – Blending zone with Madrona and Union Mills reservoir (337 zone blended
water). S27 to be treated but new WQP site needed to establish baseline conditions.
2) Treatment installation for the sources to increase entry point pH to a minimum of 7.4
a) 400 Zone
i) Install CCT at S23/28 (will also impact 337 zone)
ii) Install CCT at S17
iii) Install CCT at S27 (will also impact 337 zone)
b) 337 Zone
i) Increase caustic dose at S04
ii) Install CCT at S18 and S01-replacement
With these installations, at least 84% of the available source pumping capacity will be either noncorrosive or treated for corrosion control. Additional capacity will likely be available with the redevelopment of S17 and S01.
3) After treatment installation at S17, S23/28, and S18, WQP monitoring to determine the need for
increasing EP targets or modified well operational strategies for achieving the goal of at least pH 7.0
in the DS blending zones, and confirm the need for construction/installation of treatment at S27.
a) pH, alkalinity, and conductivity
b) Biweekly monitoring at entry points
c) Monthly monitoring at the current 12 WQP sites and the additional sites selected for targeting
the areas summarized in item 1b) above.
4) After the treatment systems at S17, S23/28, and S18 have been operational and meeting EP targets
for at least 4-6 months, conduct 2 consecutive 6-month rounds of LCR tap monitoring in accordance
with the LCR requirements (prioritizing Tier 1 homes).
5) Evaluate Results using Flow Chart below (to be re-evaluated according to requirements of the
6) If results indicate optimized corrosion control, provide results and recommendations for optimal
water quality parameter set points for each entry point and within the distribution system (by
pressure zone if appropriate) to the Department of Health.
90th percentile of LCR Tap Samples
Pb ≤ 0.005 mg/L Cu ≤ 1.30 mg/L
Pb 0.006-0.015 mg/L Cu ≤ 1.30 mg/L
b(3) Criteria Met, System Optimized
WQPs within optimal range?
Identify Risk Areas
System Optimized Increase Treatment Levels if Possible
Complete Investigative Tap Sampling Following DOH’s Hot Spot Approach. If the
issue is Copper, then prioritize on new construction
Evaluate Alternative Operational Strategies to Increase the Proportion of Non-Corrosive or
Treated Sources to the Area
Pb ≤ 0.015 mg/L Cu ≤ 1.30 mg/L
System Optimized Pb/Cu ≥ AL
Install Treatment to the source(s) supplying the
7/13/2018 11:07 AM J:\DATA\CEG\118-017\TECH MEMO\RH2 TECH MEMO RE COST FOR PH ADJUSTMENT FACILITIES.DOCX
Client: Confluence Engineering Group/City of Lacey
Project: Water Quality Consultant
Project File: CEG 118.017.01.101 Project Manager: Dan Mahlum, PE
Composed by: Barney Santiago, PE
Reviewed by: Dan Mahlum, PE and Rick Ballard, PE
Subject: Well Nos. 1, 2, and 3, Well No. 4, and Madrona Wells pH Adjustment Facilities
Date: July 13, 2018
BACKGROUND Washington State Department of Health (DOH) has required the City of Lacey (City) to
update its 2014 corrosion control study and identify additional treatment to optimize
corrosion control. The City retained Confluence Engineering Group (Confluence) to
evaluate current source and distribution water quality and recommend treatment that
focuses on pH adjustment at the City’s sources. The City will use this information to
update its 2014 corrosion control study for DOH approval.
Confluence determined that the preferred locations for implementing additional pH
adjustment would be the Well Nos. 1, 2, and 3 site (DOH Source # S01 and S18), Well
No. 4 (S04), and the Madrona Well Nos. 1, 2, and 3 site (S23 and S28). Confluence
recommended caustic soda doses for these sources and retained RH2 Engineering, Inc.,
(RH2) to assist with estimating costs of the new pH adjustment facilities. This technical
memorandum summarizes the expected chemical usage, sizes chemical feed and storage
equipment, and presents conceptual construction and project cost estimates for the
proposed facilities. Well No. 4 currently has a pH adjustment system; this evaluation will
include operational changes to accommodate higher caustic soda doses at this site.
Signed: 07/13/2018 Signed: 07/13/2018
Technical Memorandum RE: Well Nos. 1, 2, and 3, Well No. 4, and Madrona Wells pH Adjustment Facilities July 13, 2018
7/13/2018 11:07 AM J:\DATA\CEG\118-017\TECH MEMO\RH2 TECH MEMO RE COST FOR PH ADJUSTMENT FACILITIES.DOCX
WELL NO. 4 Well No. 4 currently has an existing pH adjustment facility that includes three
1,000-gallon storage tanks for 25-percent caustic soda and two metering pumps for
injection. Confluence determined that an increase in caustic soda dose is required to meet
the short-term target pH of 7.6. Confluence also provided an upper limit caustic soda
dose for future planning. These doses, along with source flows, maximum daily hourly
operation, and metering pump and chemical usage calculations are shown in Table 1.
Maximum daily hourly operation was estimated from the City’s 2017 12-month water
Table 1: Well No. 4 Caustic Soda Boost Calculations
Notes: Treatment quantities will be revisited once a new well is drilled and water quality and
pumping capacity is updated for the expanded site.
gpm = gallons per minute
NaOH = sodium hydroxide or caustic soda
MDD = maximum daily demand
mg/L = milligrams per liter
The short-term caustic dose boost would require an additional 0.28 gallons-per-hour
(gph) increase in existing metering pump speed to meet the target pH of 7.6. An
additional 135 gallons of 25-percent caustic soda will be consumed per month. To boost