Gel Toral paper attached with supporting data
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yenceg lechnology
Detection and Evaluation of Elevated Lead Release from Service
Lines: A Field Study
Miguel A. Del Toral,**? Andrea Porter,’ and Michael R. Schock?
TUS. Environmental Protection Agency, Region 5, GWDWB, 77 West Jackson Boulevard, Chicago, Illinois 60604, United States
*U.S. Environmental Protection Agency, ORD, NRMRL, 26 W. Martin Luther King Drive, Cincinnati, Ohio 45268, United States
®& Supporting Information
& INTRODUCTION
Background. Most lead in drinking water comes from
premise plumbing materials and lead service lines (LSLs). LSLs
are generally the largest source of lead in drinking water when
they are present in public water systems.’ The 1986 Safe
Drinking Water Act Amendments banned new lead pipes in the
potable water network, but a legacy of millions of partial or
whole LSLs remains in many public water systems.” Where the
term “lead corrosion” is used, it refers to the corrosion of lead
plumbing materials that result in the transfer of dissolved or
particulate lead into the drinking water.
The Lead and Copper Rule (LCR) sampling is intended to
measure the lead levels in drinking water to assess the
effectiveness of corrosion control treatment utilized by public
water systems (PWSs) to minimize lead in drinking water.
PWSs are required to use sampling sites that are presumed to
be the highest-risk sites for lead release, and to optimize
corrosion control to minimize lead levels at consumers’ taps.
Most published sampling studies typically focus on systems
having high lead levels or systems that have experienced
challenges in attempting to balance LCR compliance with
various other treatment or water quality objectives. Except for
LCR compliance data, little published data exists or is available
for systems that are considered to be operating with optimal
corrosion control and meeting the lead action level (AL) in the
LCR. This study focuses on a system that is considered to have
optimized corrosion control using a blended phosphate, with a
relatively stable water quality, and compliance results
historically well below the lead AL. This situation is
representative of a large percentage of systems serving
100,000 or more people that utilize orthophosphate or blended
phosphates for corrosion control and the vast majority of
his article not subject to U.S. Copyright.
bie 2013 by the American Chemical
ep ACS Publications
systems are meeting the lead AL based on the current sampling
protocol in the LCR. Additional information on the LCR and
study is available in the Supporting Information (SI). This
study focused on whether (1) the current LCR compliance
sampling protocol adequately captures the peak lead levels in a
water system; (2) “preflushing” (PF) results in capturing lower
lead levels in samples compared to samples collected under
normal household usage (NHU) conditions; (3) a first-draw
sampling protocol appropriately determines the adequacy of
optimal lead corrosion control in water systems with LSLs; and
(4) there is seasonal variability in the sampling results using the
different sampling protocols.
System Information. The Chicago Department of Water
Management (CDWM) operates two similar conventional
surface water filtration treatment plants serving approximately
5.4 million residents, including those in 125 suburbs. Lake
Michigan is the sole water source, with relatively stable water
quality leaving the treatment plants and in the distribution
system (Table 1). Before the LCR, CDWM utilized pH/
alkalinity adjustment for corrosion control. CDWM switched to
a proprietary blended phosphate at both plants between 1993
and 1994 which is still used as the primary corrosion control
treatment.
The LCR requires public water systems to collect lead
samples using a first-draw (FD) sampling protocol, and samples
were collected almost exclusively from single-family homes with
LSLs as required by the LCR sample site selection require-
Received: January 23, 2013
Revised: June 24, 2013
Accepted: July 23, 2013
Published: July 23, 2013
| Environ, Sci, Technol. 2013, 47, 9300-9307
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Environmental Science & Technology
Table 1. Water Quality Data 2011
temp (°C) 4 mA 5 23
turbidity (NTU) Ol 0.2 Ol 04
pH 75 78 We 78
Ch, residual (mg/L) 1.0 12 07 0.9
total alkalinity (mg/L as CaCO,) 103 108 98 108
chloride (Cl, mg/L) 16 20 17 20
sulfate (mg/L) 29 31 29 30
Ca (mg/L) 34 39 34 39
PO, (mg/L) 04 0.6 0S 05
total PO, (mg/L) 08 ll 08 12
Al (ug/L) 34 126 29 113
Fe (ug/L) <5 <5 <5 34
Mn (ug/L) <3 <3 <3 <3
ments.’ Since the initial LCR monitoring, Chicago has
exceeded the lead AL only once, during July-December
1992, with an average 90th percentile compliance monitoring
value between 1999 and 2010 of 6 g/L (SI Table $2).3
The LCR requires 1-L, FD tap samples of water that has
stood motionless in the plumbing system (i.e. has stagnated
within the plumbing) for at least 6 h. The two variants of the
FD sampling protocol currently used by public water systems
are defined herein as the NHU first-draw sample, where water
is used in a normal household manner, and then allowed to sit
motionless in the plumbing for at least 6 h before the sample is
collected; and the PF first-draw sample, where the water is ran