Mike,
In response to your letter dated 9/10/14 and our meeting on 11/07/14 please find attached a draft of the OER for your
review and comment.
Jeffrey R. Hansen
Senior Project Manager
Lockwood, Andrews
& Newnam, Inc.
RUE A DALY COMPANY
1311 South Linden Road, Suite B « Flint, MI 48532
T 810.820.2682 C 810.333.3201
www.lan-inc.com *
[email protected]
CONFIDENTIALITY AND PRIVILEGE NOTICE: This email communication, including any and all attachments, (collectively, this “Communication’), is intended
solely for the person(s} to whom it is addressed. This Communication may contain information that is privileged, confidential and/or proprietary. Any unauthorized
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and destroy any and all copies of this Communication.
xxxEND_PAGE:deq04_b576_5666_6018_275
Operational Evaluation Report
City of Flint ine
Trihalomethane
Formation Concern
November. 2014
Lockwood, Andrews
& Newnam, Inc.
A ALEO-A-DALY COMPANY.
xxxEND_PAGE:deq04_b576_5666_6018_276
CITY.OF. FLINT
Operational Evaluation Report
December 1, 2014
TABLE OF CONTENTS
~1. Detroit Water & Sewer Department.
25. Karegnondi \ Water Authority
i Interim Period
_3. Pump Stations —— __ ee 1
BL Operations & Maintenance : __. A
A
- 12
_. ‘Water System Hydraulic Modeling ; ; ; : AD
A. Simulation. of - 12
2: 42
j Lockwood, Andrews
Bape: lon & Newnam, Inc.
A LEGA DALY COMPANY
xxxEND_PAGE:deq04_b576_5666_6018_277
CITY. OF. FLINT
Operational Evaluation Report
December 1, 2014
TABLE OF CONTENTS
~V, Recommendations to M i imize Future OL “Exceedances
urce
__ Operational Recommendations
_ Infrastructure Change Recommendations
str System 7
1. Manage ' Water Age_
a. Storage Tanks _
_b. Cast tron, Pipes _
. Booster Disinfection _
E. Categorization of Actions —
_ VI, Figures
1, 2014 DBP Test Results
wet 2002 WTP Treatment Recommend itions
“43
13.
137
14
14
14.
15
15.
15_
15
“15
15.
“45
Page ii
lon
Lockwood, Andrews
& Newnam, Inc.
A LEO A DALY COMPANY
xxxEND_PAGE:deq04_b576_5666_6018_278
CITY OF FLINT
Operational Evaluation Report
December 1, 2014
EXECUTIVE SUMMARY
Environmental Protection Agency (EPA) and Michigan Department of Environmental Quality
(MDEQ) regulations require that public water suppliers test drinking water quarterly
throughout the distribution system for disinfectant by-products (DBP’s). Two categories of
DBP’s, tri-halomethanes (THM) and halo-acetic acids (HAAS), are regulated and must be
tested for. The City of Flint began operation of their water treatment plant (WTP) full time
with the Flint River as the source on April 25, 2014. Since that time, two quarters of samples
taken indicate that future violations are inevitable for total THM without some modifications
to the water system. In response, the City hired Lockwood, Andrews & Newnam, Inc. (LAN)
to complete this Operational Evaluation Report (OER) in conformance with EPA guidelines
with the goal to determine the cause(s) of high levels of THM and evaluate possible solutions.
The EPA promulgated the Stage 2 Disinfectants and Disinfection By-Products Rule (DBPR) in
January 2006 which set maximum contaminant levels (MCLs), for total trihalomethanes
(TTHM) and HAAS based on an annual running average,tested quarterly, for a given
sampling location, The City of Flint reports levels from 8 sampling test locations. Of the two
quarterly sampling cycles since Flint began operating the: Il time, HAAS levels have
been acceptable but TTHM levels have been high at all:8.
quarters of sampling
data with the most current period counting twice. re, the tity of Flint has not yet
experienced a violation of the TTHM MCL becai ly 2 quarters of data have been
indica id of an MCL exceedance later this
year.
A number of issues have been identified
measured.
Hon i “hich has resulted in increased chlorine feed.
¢C reased chlorine demand.
ing contributed to chlorine demand.
distribution system contributing to chlorine demand.
tribution system due to less than ideal configuration of
side pump stations.
stagnant water in some areas.
High chlorine'de in filters,
High THM form potential (THMFP) in source water.
Less than optimal removal of THM precursors
VPSyeN =
GoM
ACTION PLAN
The City of Flint has signed an agreement with the Karegnondi Water Authority (KWA) to
purchase raw water drawn from Lake Huron, The KWA system is currently under
construction and expected to be operational by late 2016. The water supply from Lake Huron
will have entirely different water quality characteristics from the Flint River and those
characteristics are expected to yield drastically reduced DPB formation. With that, non-
structural options to help reduce THM levels are much preferred over solutions requiring new
construction. Therefore, two categories of actions have been devised: Stage 1 being actions
that can be completed relatively quickly without major construction and Stage 2 consisting of
either long term actions or solutions requiring major construction. The City has completed or
intends to complete Stage 1 Actions by February 16, 2015, the week in which the next
quarterly sampling is to be done. Stage 2 actions are to be implemented only if Stage 1
Page 1 of 16 Lockwood, Andrews
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A LEG A DALY COMPANY DALY COMPANY
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CITY OF FLINT
Operational Evaluation Report
December 1, 2014
actions are ineffective in adequately reducing TTHM levels and therefore Stage 2 is
contingent upon the outcome of Stage 1.
Stage 1 — Immediate Actions
¢ Hire ozone system manufacturer to troubleshoot ozone system
¢ Bench scale jar testing
© Match existing process and access possible areas of improvement
o Simulate potential modifications to treatment process
o Evaluate coagulation and flocculation polymer aid feeds to assist with TOC
removal
© WTP operational changes
o Discontinue softening bypass stream to reduce chlorine demand
o Disinfection of filter beds to reduce chlorine dei
o Possibly begin coagulation and flocculation pe
TOC removal depending on bench scale test,
¢ Increase water main flushing efforts to minimize stagnant water
er aid feeds to assist with
d potential solutions
Storage tank volume use
Possible broken closed valve locatio!
Locations in need of flushi
Lower high water levels in
o0000
Stage 2 — Contingent Actigi
Fix ozone system
nd flocculation polymer aids to lower TOC, if not
Increased main flushing based on water modeling results
Continue valve replacements with water model assistance
Emphasize cast iron pipes on water main replacement priority list
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Page 2 of 16 Lockwood, Andrews
&Newnam, Inc.
® LEG A DALY COMPANY
xxxEND_PAGE:deq04_b576_5666_6018_280
CITY. OF FLINT pats
Operational Evaluation Report as
December 1, 2014
I. BACKGROUND
The City of Detroit Water and Sewer Department (DWSD) has historically provided drinking
water for the City of Flint and Genesee County. In the late 1990's growing concern regarding
the reliability of the DWSD supply prompted the City of Flint to upgrade their existing water
treatment plant (WTP). Those improvements, defined as Phase |, were completed in 2005
and were intended to allow the Flint WTP to operate, using the Flint River as the source, for
an extended period of time in the event that supply from the DWSD was temporarily
interrupted. Additionally, the Phase | improvements set the stage for Flint to break free from
dependence on the DWSD supply and water charges over which they had no control.
A. WATER SUPPLY TRANSITION
1. Detroit Water and Sewer Department (DWSD)
Until recently the Genesee County and Flint region had been provided drinking water
by the DWSD. However, due to excessive cost increases and reliability issues with
the DWSD system other options had to be explored
2. Karegnondi Water Authority (KWA)
In 2010 the Karegnondi Water Authority
developing a new water supply from Laké region in lieu of the
DWSD supply and the City of Flint elect he KWA expects the new system
which is currently being constructed to become operational in the fall of 2016.
>
méd for the purpose of
3. Flint River — Interim Period
With a renewing water supply ai
terminated by the DWS'
expected to be operati
rt
016, the City of Flint decided to initiate
tilizing the Flint River as the interim water
ere necessary for the Flint plant to become
report, Phase ll improvements to the Flint WTP
e been made to allow the plant to operate full time with
e or the KWA supply as the source.
source. A variety of V
a full time plant. For p'
are improvem
either the Fl
B. TTHM PEND
The calculation for de ning if the MCL has been violated for TTHM is:
(2 x current quarter value + previous 2 quarter values) / 4
Flint has completed tests for 2 quarters and therefore has not violated an MCL limit to
date. However, the third quarter of sample data is likely to provide MCL exceedances at
all 8 sampling sites. Test results are tabulated below.
Lockwood, Andrews
Page 3 of 16 Ke] p) & Newnan, Inc.
A LEO A DALY COMPANY
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CITY. OF FLINT
Operational Evaluation Report
December 1, 2014
TABLE 1.— 2014 DBP TEST RESULTS
1) 3719 Davison - McDonalds
2) 822 S. Dort Hwy - BP Gas Sta.
3) 3302 S. Dort Hwy — Liquor Pal.
4) 3606 Corunna — Taco Be
5) 2501 Flushing — Univ. Market 38 17
6) 3216 MLK — Salem Housing 41 25
7) 5018 Clio — Rite Aid 49 30
8) 6204 N, Saginaw — N. Flint Auto 50 37
TTHM MCL = 80 ug/l
HAAS MCL = 60 ug/l
C. WATER TREATMENT PLANT RECENT IMPRO
1. Phase I WTP Improvements
Since 1965, the Flint WTP has remained >
DWSD primary supply. Typically the seco
expected to be needed only durin rersency uations and normally is designed for
Conversely, Phase | improvements \
WTP in order to allow for an exte vort term aried (6 weeks) because of the
would fail and remain out of service for an
extended duration. R
plant and as such
é provements a treatability study was completed by
n, LLC (AB&H) in 2002. The Treatability Study evaluated
Point of Dosage
: : Purpose Application (mg/l)
Soden erage Zebra mussel control Intake 0.3
Ozone Taste & odor removal, disinfection
Turbidit & TOC removal Rapid mix 2.0
Turbidity & TOC removal Floc basin 0,05
| Softening
Softening basin 175
Ferric chloride
Floc aid polymer
Lime
|
|
|
Diffusor basin 1.5 |
Soda ash Softening Softening basin 52
Carbon dioxide H_ adjustment Recarb basin 37
Media filters Filtration Na Na
Chlorine { Disinfection | Filter effluent {__1.0
Lockwood, Andrews
Page 40016 Kp] &Newnam, Inc.
A&A CEO A DALY COMPANY
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CITY OF FLINT.
Operational Evaluation Report
December 1, 2014
Of the recommended items, zebra mussel control, coagulant and flocculation
polymer aids, and soda ash feed have not been incorporated into the treatment
process.
3. Phase Il WTP improvements for Full Time Operation
Phase Il WTP improvements are those needed to convert the Flint WTP from a back-
up supply to a primary supply plant. A number of improvements have already been
constructed as they were necessary to operate full time, treating water from the Flint
River, The improvements under the title of Phase Il that have been completed or are
nearly complete include upgrades to the lime sludge lagoon, the lime sludge lagoon
decant and disposal system, decant pump station and force main, installation of mid-
point chlorination before filtration, and upgrade of the electric feed sub-station.
Additional improvements to the Flint WTP that are to be completed to become part of
the normal treatment process using water supplied by thed<WA are:
« New oxygen and nitrogen storage facilitie: he ozone system (under
construction)
¢ New coagulant feed system
e Electrical
o Pump Station #4 upgrades (under
o SCADA and controls upgrades
o Filter transfer pump station \ feeders
e Installation of the future raw water
construction) :
* Pump replacements lation in the low and high service pump
station (under constry
Lockwood, Andrews
Page 5 of 16 ja Nn & Newnam, Inc.
ALEOQA A LEO A DALY COMPANY COMPANY
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CITY.OF FLINT
Operational Evaluation Report
December 1, 2014
Il. SOURCE WATER EVALUATION
A. DATA ANALYSIS
Based on past data collected and the 2002 Treatability Study by AB&H, the Flint River
water quality varies seasonally with higher hardness and alkalinity experienced in the
winter. Higher magnesium concentrations are also experienced in the winter, adding
difficulty to the settling process due to neutrally buoyant floc. General water quality
average characteristics recorded for the 2002 Treatability Study as compared with average
characteristics recorded this year are shown in Table 3 below.
TABLE 3 — FLINT RIVER WATER QUALITY CHARACTERISTICS
: : Hardness
Turbidity | TOC | Alkalinity Total Col.
NTU |. Mell A Mgi/l ; : “| Count/day.
870-1230
(7300 max)
1900-9000
(48,300 max)
7.9 9.4
10.3
5/22/14
215
investigation by City staff revealed
significantly over the past 10+ years. Note tha’
ibuted to the total Coliform count.
a sewer leak upstream of the plant that may have
The leak was subsequently repaired.
B, CONCLUSIONS
Considering the minor ch Fi ver water quality, much of the information
contained in the 2002 Treatabili &H remains relevant today. Data from that
ly with higher hardness and alkalinity in the winter
kalinity, magnesium concentrations tend to be reduced by run-off
ikely?380-440 micrograms per liter as measured between April
. The City intends to re-test the raw water to confirm the
‘ed. Results are pending.
2001 and Jan
THMFP has not
In development of the 2002 Treatability Study, processes were simulated which resulted
in low THMFP. Therefore, information contained in that report will be used to assist with
establishing a baseline jar testing procedure as discussed further in Section III.
Lockwood, Andrews
Page 6 of 16 Kp] & Newnam, Inc.
RLEG A DALY COMPANY
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CITY OF FLINT
Operational Evaluation Report
December 1, 2014
Ill, TREATMENT PROCESS EVALUATION
A. EXISTING PROCESS DESCRIPTION
The existing WTP consists of an intake with screening from the Flint River, low lift
pumping, ozonation, rapid mix, flocculation, settling, softening, recarbonation, filtration,
storage and high service pumping. A process diagram is shown as Figure 1.
1. Intake
A 72” diameter pipe draws water from the Flint River through 2 traveling screens to
the low lift pump structure. No chemicals are currently fed for Zebra mussel control
or pre-oxidation as recommended by the 2002 Treatability Study. Manual removal of
zebra mussels proved to be more economical than installation of chemical feed
equipment considering the short term need.
2. Ozone
There are 2 ozone generators designed to provide ad
up to 36 mgd. There are 3 ozone contact b
designed to produce 900 Ibs/day at 10% con
concentration each. Recent readings
approximately 700 Ibs/day at 4% concent
ate ozone for a WTP flow of
e ozone generators were
to 1300 Ibs/day at 6%
=,production rate of
the purposes of taste
current ozone feed might not be
optimized to realize additional TOC removal: benefits demonstrated by previous tests.
Also, less than optimal ozonation h i ed chlorine feed.
3, Rapid Mix
East and West rapid mi ‘
basins. Each rapid mix iberyi ed with a 5 hp mixer.
The WTP contains two fall locculation basins, east and west, and each
basin provide: ] adually slowed mixing from inlet to outlet. There are
Vebasin with VFDs to control mixing speed. The 2002
sd feeding both coagulation and flocculation polymer
is being used today because turbidity and TOC removals
t to meet regulatory requirements.
have been suff
5. Settling
Primary clarification takes place within 3 basins containing plate settlers. The settlers
are operating as designed.
6. Softening
Again, there are two basins for softening: east and west. Each basin is 120’ in
diameter and contains a solids contact softening unit. Each softening basin/unit has a
design capacity of 18 mgd. Low lift pumping limitations, flow control to the basins,
and fluctuating demands have made it difficult for WTP staff to stabilize the softening
process. Softening is accomplished by feeding lime. The decision was made by the
City not to feed soda ash in order to remove non-carbonate hardness because
acceptable hardness levels could be achieved with lime feed only and softening is
short term until Lake Huron water becomes available.
Lockwood, Andrews
Page 7 of 16 lon & Newnam, Inc,
A LEO A DALY COMPANY
xxxEND_PAGE:deq04_b576_5666_6018_285
CITY OF FLINT
Operational Evaluation Report
December 1, 2014
7. Recarbonation
Recarbonation for pH adjustment is accomplished in east and west recarbonation
basins between and to the north of the softening basins. Carbon dioxide storage and
feed equipment is located west of the recarbonation basins.
8. Filtration
Filtration is accomplished with 12 dual media filters, equally sized and designed to
filter 3.0 mgd each. Media consists of 12” of sand and 18” of anthracite. The filters
have been operated intermittently over the years due to the standby nature of the
WTP and until recently, chlorine injection took place downstream of the filters. It is
possible some microbial growth has developed in the filters.
9. Disinfection
Limited disinfection is provided by ozonation, but the primary form of disinfection is
chlorine fed prior to filtration and prior to finish water storage / high service pumping.
The intermediate chlorine injection location was reéently constructed under the
Phase II, Segment 1 contract. x
10. Clear Well & Pumping
The pump building sits adjacent to a 3 M
high service pumps.
gntains both low and
B. JAR TESTS / EXPERIMENTS
1. Approach
There are several well practiced met
disinfectant can be changed.to an al
Second, additional treatment 4ys'
(depending on the nat
Lastly, the existing t
precursor as possible.
only strategy thats
re
oe es has a lower tendency to form DBPs.
te uch as activated carbon or air stripping
ce s) can be added to remove DBP precursors.
1 Pioeesses ‘an be optimized to remove as much DBP
options, optimizing existing treatment processes is the
quire the construction of new and expensive facilities. It
receiving Lake Huron water in approximately two
‘a completely different chemistry from the Flint River.
tituted to address THM levels using Flint River water are
y’ for Lake Huron water and may even be inappropriate.
Therefore, thos ns Which require addition of new treatment processes are
undesirable at this time. In recognition of this upcoming change in water source, this
study will concentrate on improving the existing processes, rather than adding new
ones. New treatment processes will only be recommended if operational changes to
the existing treatment train prove ineffective.
Recent sample test results suggest that most of the DBPs are formed in the distribution
system rather than within the treatment plant. Therefore, the most logical approach is
to reduce the DBP formation potential (DBPFP) rather than simply lowering the levels
of DBPs leaving the plant. During bench scale testing, formation potential (FP) levels
will be the primary indicator of success or failure of any proposed process
modifications.
2. Protocol
Bench scale pilot testing is intended to reflect actual plant operating and hydraulic
conditions so the bench scale treatment units will be sized based on various
dimensionless factors to ensure the pilot treatment matches the actual system, Bench
scale ozonation is not practical due to time and cost limitations. Therefore, water
Page 8 of 16 Lockwood, Andrews
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WLEG A DALY COMPANY
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samples will be withdrawn following the plant ozone basin. These samples will be
transported to the laboratory where they will be dispensed into square testing jars.
The jars will act as rapid mix, three-stage flocculation, and settling. Rapid mix and
flocculation conditions will be matched to the plant based on “Gt” values. The “G”
value is a measure of the mixing intensity and is a function of mix time, viscosity of
the liquid, and mixing power applied to the water. “Gt” then, is a size scaling factor
where time has been accounted for. Settling time will be scaled to match the shorter
settling depth of the testing jars. After settling, samples will be decanted from the test
jars. The decanted samples will then be lime softened; softening conditions will be
similarly matched ‘on the basis of “Gt’. Fluoride will be added and carbon dioxide
sparged into the samples to reduce the pH. The water will then be vacuum filtered
through filter paper, sized to simulate the plant's dual media filters. The samples will
be dosed with excess chlorine and allowed to react for seven days before testing for
DBPs to determine the formation potential.
Although these conditions may be refined based on new information, we anticipate
the following:
TABLE 4—- BENCH SCALE TEST. MIXING INTENSITIES
_ Process _ ‘Duration
Cecaation :
Rapid Mix 25 sec
Flocculation, Stage 1 9 min
Flocculation, Stage 1 9 min
Flocculation, Stage 1 9 min
Settling 10 min
Softening 10 min
Recarbonation na
and chemical dosag
conditions wi
Lockwood, Andrews
Page 220816 Ks] p) &Newnam, Inc.
A’ (EO A DALY COMPANY
~ Current Usage 2002 Study
Ozonatie 4.66 mg/l 1.5 mg/l
Ferric Chlofi 7.7 me/l 40 mg/l
Coagulant Aid Polymer Not used 2.0 mg/l
Flocculation Aid Polymer Not used 0.05 mg/l
Lime 120 mg/l 175 me/l
Soda Ash Not used 52 mg/l
Cationic Softening Polymer Not used
Anionic Softening Polymer Not used
Fluoride
Carbon Dioxide g
Chlorine 6.3 mg/l 1 mg/l _|
xxxEND_PAGE:deq04_b576_5666_6018_287
CITY OF FLINT
Operational Evaluation Report
December 1, 2014
3. Considerations
The 2002 Treatability Study did not note significant formation of DBPs. This may be a
function of different Flint River water chemistry at that time. However, recognizing
the considerable differences in chemical usage and dosages between that study and
current operations, those differences in chemical use and dosage are an obvious
starting point for optimizing treatment to prevent DBP limit exceedance.
Although it is believed that optimization of current treatment can correct the DBP
issue, should optimization of present treatment prove insufficient, alternate residual
disinfectants (chloramines and chlorine dioxide) will be investigated as additional
treatment measures,
4. Results
[To be completed following jar testing and experimentation]
5. Conclusions
{To be completed following jar testing and experim:
Lockwood, Andrews
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A LEO A DALY COMPANY
xxxEND_PAGE:deq04_b576_5666_6018_288
CITY. OF FLINT.
Operational Evaluation Report
December 1, 2014
IV, DISTRIBUTION SYSTEM EVALUATION
EPA guidance for the distribution evaluation portion of an OER is focused on identification
and isolation of a specific portion of the distribution system that led to the exceedance. The
circumstances of Flint’s apparent pending TTHM exeedances are unusual in that a new
supply has been implemented which clearly corresponds to the high TTHM sample results.
Despite obvious implications to the primary cause of increased TTHM levels, value remains
in evaluating the distribution system as there may still be distribution improvements that can
be made to help alleviate the problem.
Evaluation of the distribution system, including modeling, was recently added to LAN’s scope
of services. When finished, information will be provided to complete the following topics in
this section.
A.
INFRASTRUCTURE
1. Piping
According to the most recent MDEQ Sanitary
estimated to contain 70% cast iron, 20% d e iron,
water mains, Unlined cast iron pipe can beéome pitted, allowing colonization sites
for microorganisms leading to chlorine d id. Additionally, much of the piping in
the system is aged and in poor condit sed chlorine demand could be
resulting from biofilm in older pipes and from breaks/repairs.
e distribution system is
concrete and 8% steel
The City utilizes City Point softwar
and prioritize replacements. Areas
include Fenton Road, Ather
Drive. The extent of
ort Highway, Averil Street, and Boulevard
t known but any water main replacement
properly.
2. Storage
3. Pump Stations
{To be completed]
*® Condition
© Pump capacity evaluation
¢ Valve condition and pressure zones
OPERATIONS AND MAINTENANCE
1. Pump Station & Storage Operations
{To be completed]
* Control of pressure districts
¢ WTP Pump Station (No. 4)
© Cedar Street Pump Station
© Westside Pump Station
Lockwood, Andrews
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ALLO A DALY COMPANY
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CITY OF FLINT
Operational Evaluation Report
December 1, 2014
* Torrey Road Pump Station
¢ High and low levels in tanks
2. Booster Disinfection Practices
Booster disinfection is provided at the Cedar Street and Westside pump stations.
Sodium hypochlorite is applied while the reservoirs are being filled.
3. Changes in System Demands
{To be competed]
e Long term decline in demands
e Short term fluctuations — max day in winter due to high volume of main
breaks
C, WATER SYSTEM HYDRAULIC MODELING
[To be completed]
1, Simulation of Existing System
Match existing conditions, particularly chlo
at plant and residuals at 10 locations in e.
chlorine feed data
2. Identification of Deficiencies
Specific issues to look at:
Page 12 of 16 Lockwood, Andrews
&Newnam,inc.
*® LEG A DALY COMPANY LEQ A DALY COMPANY
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CITY. OF FLINT
Operational. Evaluation Report
December 1, 2014
V. RECOMMENDATIONS TO MINIMIZE FUTURE OEL EXCEEDANCES
A, SOURCE
The City of Flint has already committed to the change from the Flint River as the water
source to Lake Huron under the KWA system, planned for late 2016. The risk of future
TTHM limit violations will decline substantially with the use of water from Lake Huron
due to much lower DBP precursors. It is important to recognize that the Flint River will
become strictly an emergency supply when the KWA supply becomes available and any
investments toward the Flint River should be contemplated accordingly.
Recommendations discussed below in this section apply to the Flint River as the source,
Reverting to supply from the DWSD until the KWA supply is available as an option.
However, the DWSD has stipulated that a $4 million connection fee would apply and
current water rates would include approximately $900,000. month flat fee plus usage
charges, Therefore, utilizing the DWSD for interim supply if cost prohibitive under the
terms defined by the DWSD.
1. Watershed Management
time.
2. Monitoring “ls,
chara istics as part of standard preparation
of Monthly Operating Reports,(MOR: Changes are recommended at this time.
3. Intake Operation
The 2002 Treatabili
permanganate as a
permanganate _i j
provided b'
2camamended pre-oxidation in the form of sodium
‘the“intake. However, pre-oxidation with sodium
4, Seasonal
Past data ind Flint River is influenced by groundwater and in particular,
dolomitic spring “Water. The result is hard water with high concentrations of
magnesium and sulfate. Also, hardness and alkalinity are higher during the winter.
Upon initiation of supply from the Flint River, the City made the decision to soften
with lime only to focus on removal of carbonate hardness. One potential
modification that could assist with TOC removal and thus decrease THMFP would be
lime and soda ash softening. If implemented soon, the procedural change would be
timely as it would also address increased hardness expected going into this winter.
5. Upstream Contamination Issues
Upstream contamination issues are extremely difficult to prevent and even if detected
are difficult to locate. Evaluation of raw water data collected for MORs is the easiest
manner in which to detect upstream contamination issues because the data is already
collected for treatment purposes. In fact, high total Coliform readings signaled a
potential issue recently that the City identified and removed.
An upstream monitoring and warning system could be established to attempt to
detect spill event type contamination early enough to cease intake prior to the
Lockwood, Andrews
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ALEO A DALY COMPANY
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CITY. OF. FLINT
Operational Evaluation Report
December 1, 2014
contamination reaching the WTP. However, given the imminent conversion to the
KWA supply, the period of full time use would likely be far too short to achieve
payback on the capital expenditures,
B, TREATMENT PROCESS
1, Operational Recommendations
¢ Coagulation and flocculation _polymer_aids: The 2002 Treatability Study
suggested the use of coagulation and flocculation polymer aids. These
polymer aids were shown in the 2002 Treatability Study to increase TOC
removal and thereby reduce THMFP. Further evaluation will be. completed
during jar testing.
e Discontinue softening bypass: The City was previously bypassing a portion of
flow around the softening basins because hardness levels did not warrant
softening of the full stream. However, this p e was discontinued because
it was believed the bypass stream was conttibuting to chlorine demand and
preliminary data has supported that belief” demand dropped 0.5 -—
1.0 mg/l following elimination of the b
e Soften with lime and soda ash: Ri
efficacy of this option will be evaluates
Disinfection of filter beds:..In case
ing jar testing.
‘e has been microbial growth it is /
treated with chlorine and rinsed. A |
|
|
tream of the filters during the first
in the filters should not be an issue.
atment processes: Depending on bench scale
, ht modifications to all treatment processes
JowerDPBFP.
nents rema n in good condition and the system can be easily modified
to restof Oper functionality. The City has scheduled the equipment
manufacturer to field inspect the system on December 15, 2014.
¢ Change disinfectant to chloramine or chlorine dioxide: !f other options prove
to be ineffective, conversion to another disinfectant should be fully evaluated.
Various characteristics of chloramination indicate an advantage over chlorine
dioxide, but a full analysis would provide clarity as to which would be
preferred.
¢ Install_pre-oxidant chemical feed: Hydrogen peroxide as a pre-oxidant can
enhance the activity of the ozone. This option is listed as a consideration only
if problems continue with ozonation.
e Repair upstream sewer leak: a sewer leak upstream of the WTP intake was
discovered and has already been repaired by the City.
Lockwood, Andrews
Page 14 of 16 lon & Newnam, Inc.
A LEO A DALY COMPANY
xxxEND_PAGE:deq04_b576_5666_6018_292
CITY. OF FLINT.
Operational Evaluation Report
December 1, 2014
C. DISTRIBUTION SYSTEM
Recommendations will be incorporated into this report when available. It is anticipated
details will be provided for the following topics. [To be completed]
1. Manage Water Age
a) Storage Tanks
b) Residence Time in Pipes
2. Reduce Disinfectant Demand
a) Flushing
b) Cast Iron Pipes
3. Water Modeling of Recommendations
Determine best flushing locations to reduce water age
Changes to storage tank operating levels to reduce waté
Evaluate booster disinfection
f the distribution system. Water
when freezing weather became
the closed position and believed to
A number of actions have already been taken‘in ter!
main flushing efforts were increased until late ;
prevalent. Also, numerous valves that were brokéi
have been contributing to stagnant wa’
D. BOOSTER DISINFECTION
ding booster disinfection in the distribution
pe reaction time at higher concentrations of
Considering that the Flint River is being used as the water source only until the KWA
supply is available (expected late 2016), options to address high THM formation that
require new construction or extensive time to implement are not preferred. On the other
hand, the City understands THM sample results to date dictate that some action is
necessary. Two categories have been developed to assist the City in prioritizing actions to
take. Stage 1 consists of actions that can be completed relatively quickly without major
construction and Stage 2 actions are either long term actions or solutions requiring major
construction. Stage 1 actions are to be completed first followed by evaluation of the
results prior to consideration of Stage 2 actions. Grouping of actions are shown in the
table below.
Page 15 of 16 Lockwood, Andrews
&Newnam, Inc.
ALEGA LEQA . DALY COMPANY COMPANY
xxxEND_PAGE:deq04_b576_5666_6018_293
CITY: OF FLINT
Operational Evaluation Report
December 1, 2014
_ Action
TABLE 6 — ACTION PLAN
Purpose
Troubleshoot ozone feed system
Reduce chlorine feed and increase TOC removal
Bench scale jar testing
Optimize treatment process and evaluate possible
modifications
Discontinue softening bypass
Reduce chlorine demand
Disinfect filters
Reduce chlorine demand
Increased water main flushing
Reduce water age / stagnant water
Water system modeling evaluation
Determine areas with high water age and reasons
“Stage 1
Implement coag. & floc. polymer aids,
if appropriate
Increase TOC removal
__| Modify booster disinfection feeds, if
| appropriate
Repair ozone system
Decrease water age |
Reduce chlorine feed and increase TOC removal
_ {Continue increased water main flushing
Reduce water agi
{Convert to lime and soda ash softening
Increase TOC removal
Continue valve replacements based on
water model
“Stage 2
Change disinfectant to chlorine dioxide
Install pre-oxidant feed at intake
_| Place priority on replacing cast iron
__| water mains
Samples were taken the week of Nové
the City has begun implementation of Stage 4
be noticeably affected since there has ‘nat been”
ied the third week in February. It is the City’s
rior {6 the 3 quarter of THM sampling.
quarter of sampling is due t
intent to implement Stage 1
mpl
3" quarter of testing. Although
HM results are not expected to
ugh time for a response. The next
Page 16 of 16
Lockwood, Andrews
& Newnam, Inc.
A LEO A DALY COMPANY
xxxEND_PAGE:deq04_b576_5666_6018_294
i
!
FROM FUNT °
RIVER
—
RAW WATER
SCREENS
INTERMEDIATE
CHLORINE
Genesee County
OZONE
SODIUM BISULFATE
FERRIC CHLORIDE
i
=
FLOW
METER
fe)
M
LOW LIFT OZONATION RAPID
PUMPING MIX
CARBON DIOXIDE FLUORIDE UME POLYMER
_ (ANION & CATION)
M
FLOW
METER
RECARBONATION SOFTENING
DUAL MEDIA FILTRATION
CITY OF FLINT
WATER TREATMENT PLANT
REVISIONS
THREE STAGE
FLOCCULATION
PLATE SETTLERS
POST
CHLORINE
FINISHED WATER
RESERVOIR
(2)
HIGH SERVICE .
PUMPING
WATER TREATMENT PLANT
PROCESS DIAGRAM
TO DISTRIBUTION
—
Project No. 130-10701-00t
Dae Nov. 21, 2014
Sheet
FIG 1
xxxEND_PAGE:deq04_b576_5666_6018_295
Rennaker, Joanne (DEQ)