Mike,
Thank-you for giving us the opportunity to review the city of Flint’s carrasion control plan.
We belleve it is necessary that Aint boosts orthophosphate dosage. Given that the distribution system
has not received orthophosphate in over a year, we expect that orthaphasphate will nead to be boosted
to 1} meet the dernand of the distribution systern, 2) reach the service lines and other lead-containing
components in premise plumbing, and 3} accelerate lead reduction at the consumer's taps.
Orthophosphate should preferably be added in the same form as the Detroit source which is phosphoric
acid frorn cur understanding. This is the proposed case here, however, a simple test should be
perforrned to make sure that the pH is not impacted in a significant way at the desired target dose.
We have not been able to abtain comprehensive water quality data for the finished water
characteristics of the Detroit water that will be fed to Flint, ta assess ranges af major chernical
characteristic fluctuations. However, based upon the email trail, Detroit water entering the Flint system
ppears to anly contain around 0.4 PO4/L. This concentration range is entirely too low compared to that
needed in studies presented and published in the last 20+ years that have focused on lead released
directly from lead pipes, and the salubility of the most likely lead orthophosphate pipes scalus. We alsa
strongly feel that targeted dase of 0.8 mg PO4/L is also too low, for the very same reason. We would be
glad to share with you numerous standard corrosian control and treatment reference works, best
p
g
2
ractices guides ard published resulis fram US and international lead carrasion control field and pilat
tudies. Secondly, the basis for that target (other cornmunities using Lake Huron sauree use the same
dase) is nat scientifically derived nar does it consider water quality and the current state of Hirrt's
distributian system, We have reviewed the original Detrait carrasion study and have seen same of the
LCK monitoring data, and besides the fact that it did nat directly pertain to this water source, few
dosages were tested in the cited 1994 pipe loop study, and the higher dosage than the one
implamented in the field currently was more effective. Based on the limited amount of data on the
quality of Detroit water, what we know about the history of Detroit corrosion control, we think an
orthophosphate resicual of 3 to 4 mg PO4/L should be the minimum starting test target residual for pine
passivation. itis lkely that, at least initially a higher dosage will be necessary te reach the far ends af
the distribution system and sufficiently reduce lead solubility and release from all lead sources. To allow
flexibility, we feel the design of the chemical feed and storage systems should he able to cansistently
deliver a maximum dose of 5 te 6 mg PO4/L, if substantial orthophosphate joss is observed, if the
starting dase is set far the desired residual level of 3 to 4 mg/L as PO4. We suggest that jar tests be
performed in advance of orthophosphate addition to Detroit water to evaluate the impact af
orthophosphate dase on turbidity that could result from interactions between orthaphasphate and
background Detroit water quality parameters (e.g., aluminum, calcium, ete.).
We want to stress that immediately shifting to Detroit water and adding arthaphasphate will not
necessarily transiate to immediate improvements. Furthermare, this is a change, albeit a return to past
conditions. Nonetheless, a period af system upset should be anticipated. The need for a communication
strategy and a distribution system plan are critical.
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Lastly, we see no mention of a water quality monitoring program. Two programs need to be put in place
immediately (before return to Detroit water) to 1) identify lead sources, 2} assesa treatment
effectiveness against lead release frorn all of the simultaneously operating mechanisms (solubility,
particulate release, galvanic corrosion}, and 3} assess arthaphasphate levels and stability of water
quality In the distribution systern.
There are multiple sources of lead in the Flint distribution systern to the consumers’ taps, such as: pipes;
leaded brass; leaded solder; accumulations on old galvanized steel pipes; possibly accurnulated on
copper or sorne plastic pipes. it is critical that the fate of arthophasphate in the distribution system is
understood, and how effective it is against each type of lead source, so dosing adjustment can be
properly made. For this purpose, we recornmend that a number of residences throughout Flint that
meet the following plumbing criteria, be identified for an assessment of the cantribution lead from the
different potential service line and interior plumbing sources, through detailed mapping of plumbing
materials, lengths, sizes, and location and type of inline devices and faucets using grofile sampling. For
confidence in interpretation, probably at least 5 sites fram each of the configurations will be
necessary. The configurations we would estimate to be most important (but should be changed or
added to if local construction practice indicates it's necessary}: Lead service line, galvanized steel
interior plumbing; lead service line, copper with leaded solder joints; lead service line, plastic interior
plumbing. {tis also possible that interior plumbing may differ fram the material used for the customer-
side service line segment. We would be glad to discuss the specifics of this sampling effort.
For the purpose of assessing stability of water quality in the distribution system and to inform on
orthophosphate residual adjustment, we suggest that 8 ta 10 locations in the distribution systern be
selected ta measure pH, alkalinity, orthophosphate, turbidity and iron on a weekly basis. These could be
collected from TCR sampling locations, or ather readily-accessible bulldings, should be located at a
distribution of Jocations in the distribution system and should be collected after a flush sufficiently long
to assure that “fresh” distribution system water is being measured. Research has shown that over time,
orthophosphate can reduce disinfectant demand assaciated with corroding metallic distribution system
materials. These measurements need to be performed in the field and can simply be done with a
portable HACH test kit or spectrophotometer.
A lead sarnpling plan needs ta be in place to access the effectiveness of water change and treatment
boost. LCR monitoring sites with confirmed lead service lines car: be In the sampling pool. Sampling
should consist of a 1 fiter first draw sample (LCR sample without 5 minute pre-flush}, followed by an
additional flushed sample or two depending on profile sarnple results which is intended ta capture
major lead source(s}. The specific details of this effort need to be worked out by the technical
committee as soon as possible. We would gladly work with Hinton establishing a water sampling
program to identity and verify lead service Hne sites. The olan and initlal samoling effort should be
performed before the switch so that one baseline sarnple set is collected.
Lastly, our strength does nat fall under full-scale purne and chemical feed delivery systems. We would
only say that the systems need to be scaleci-up in size to accommadate our suggested dasing needs.
Alse, there is the same discussion about diverting water to the Dort reservoir and an associated
orthophosphate feed system. We are not familiar with the reservair but are wondering if itis an open
reservoir?
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Of course this is a jot of information to share and we would gladly be available to discuss the technical
and scientific basis for our suggestions.
Let us know if you have any questions and thanks again,
Darren and Mike
Darren A. Lytle, PhB., PLE.
Branch Chief (Acting}
U.S. Environmental Protection Agency
28 West Martin Luther King Dr.
Cincinnati, Chic 45268
Phone: (513) 569-7432
Fax: (513) 487-2543
email:
[email protected]
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