Jen/all - I think things got garbled in translation...
What I was saying is that where you find Pb values that high, it is usually due to particulate lead. Not always,
but generally. Particulate lead is released sporadically from lead service lines, leaded solder and leaded brass in
a number of ways and folks tend to discount these values as anomalies, but particulate lead release is a normal
part of the corrosion process and it is universal (common) in all systems. It’s just that it is not captured as often
by the infrequent LCR sampling. If systems are pre-flushing the tap the night before collecting LCR compliance
samples (MDEQ still provides these instructions to public water systems) this clears particulate lead out of the
plumbing and biases the results low by eliminating the highest lead values. If systems are pre-flushing and still
finding particulate lead, the amount of particulate lead in the system can be higher than what is being detected
using these ‘pre-flushed’ first-draw samples. My point on that was that people are exposed to the particulate
lead on a daily basis, but the particulate lead is being flushed away before collecting compliance samples which
provides false assurance to residents about the true lead levels in the water.
Some quick notes on particulate lead release:
e Fe/Mn can transport lead from the lead service lines into the home. The lead sorbs onto the Fe/Mn
particles. In GW systems, Fe/Mn can come from the source water and more Fe from the water mains. In
SW systems, the Fe typically is released from the water mains.
e Lead released from lead service lines can also 'seed' galvanized iron pipes inside the homes. Again, the
lead sorbs onto the iron on the pipes and be released sporadically. Generally, the higher the flow, the
more Fe and Fe+Pb particulate you will likely get.
e Ifthere is a partial lead service line (lead connected to copper) you can get additional lead release due to
galvanic corrosion.
e Leaded brasses and solder can also release particulate lead under certain circumstances.
e The particulate can contain very high concentrations of lead (hundreds to thousands of ppb Pb) which is
a much higher concentration than lead paint, so even small particles can result in high lead values.
e Ifthe lead service line was disturbed (water main repair/replacement, meter installation
repair/replacement, service line leak repairs, etc.) you can have VERY high lead levels in the scale and
sediment that is dislodged from the inside of lead service lines. Here in Chicago, during a partial lead
service line replacement, we collected the scale and sediment that came into the home and we found
300,000+ ug/L lead in the scale; 125,000 ug/L Pb in the sediment. Very dangerous.
e Higher levels of PO4 (3-4 mg/L Ortho) seem to reduce the amount of particulate Pb that is released in
the absence of physical disturbances to the lead lines. Doesn’t stop it entirely, but should generally
reduce the occurrence. Caveat — Other water quality issues can change the chemical complexes that form
on the pipe, so cleaner sources with more consistent WQ form more predictable scale complexes.
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If remember correctly, Detroit is feeding PO4 for the LCR, but since Flint is no longer part of that
interconnection, I was wondering what their OCCT was. They are required to have OCCT in place which is
why I was asking what they were using.
Mike Schock is our resident expert and may be able to help out with the simultaneous compliance (Pb & DBPs)
so I would suggest that folks give him a call.
Miguel A. Del Toral
Regulations Manager
U.S. EPA RS GWDWB
77 West Jackson Blvd, (WG-15J)
Chicago, IL 60604
Phone: (312) 886-5253