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Seasonal Source Water Quality and Treatment Challenges – Town of Newburgh’s Chadwick Lake Filtration Plant
Clayton Johnson | GHD Kevin Castro | GHD James Osborne | Town of Newburgh
Tifft Water Supply Symposium
Outline
• Introduction and Scope – Existing supply
• Background • Water Quality Characterization
– Raw water – Plant water
• Filter Biofouling • Bench-Scale Testing • Plant Improvements • Questions
Tifft Water Supply Symposium
Introduction and scope – existing supply
• Town of Newburgh, NY (Town) owns and operates a water supply system serving about 25,000 people – Two sources of supply and two WTPs
• Chadwick Lake Filtration Plant (CLFP) – Conventional surface water supply (3.2 MGD) – Provides base load and backup when Delaware Aqueduct Tap (DAT)
WTP is not in service • intended to be primary supply until WQ issues occurred
• Delaware Aqueduct Tap (DAT) WTP – Previously unfiltered supply (6 MGD)
• System demands – Avg. + 3 MGD – Max. Day + 5 MGD
Tifft Water Supply Symposium
Introduction and scope
• Chadwick Lake seasonally experiences elevated levels of manganese (Mn) – Difficult to remove at CLFP – Increased treatment costs and aesthetic water quality complaints
(“brown” or “black” water) during summer months
• Treatment challenges with conventional filtration process - changes in raw water quality since 2011 storms (Hurricane Irene) – Greensand filtration - impacted by shortened filter runs and potential
biofouling
Tifft Water Supply Symposium
Introduction and scope
• GHD commissioned to perform a study to evaluate CLFP treatment performance
• Study objectives – Characterize Chadwick Lake water quality – Characterize raw water quality changes since
2011 storms – Process improvements
• Evaluate settling and filtration performance – Evaluate filter biofouling potential – Evaluate potential addition of ferrate
Source:http://en.wikipedia.org/wiki/Hurricane_Irene
Tifft Water Supply Symposium
Background
Chadwick Lake • 820 MG reservoir • Located within Hudson River drainage basin • Avg. depth < 10 ft.; max. depth 32 ft. • Surface area of 210 acres • Dimictic – complete mixing in spring and fall;
thermal stratification in summer and winter • Copper sulfate is added to reservoir as an
algaecide up to 3 times per year to control algal growth
• Raw water intake at southern end of lake 6 ft. below water surface – 36-inch diameter slotted drum screen intake
with an air burst cleaning system
Tifft Water Supply Symposium
Background
Chadwick Lake Filtration Plant • Built in 1969 and rehabilitated in 1998 • Greensand filtration constructed 2010 • 3.2 MGD capacity • Avg. daily flow of 1.6 MGD • Two parallel treatment trains – 3.2 MGD
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CHADWICK LAKE
TRAVELING BRIDGE FILTERS
TO DISTRIBUTION CHLORINE CONTACT TANK
AND CLEARWELL
RAPID MIX
FLOCCULATORS SEDIMENTATION TANK
Mn TREATMENT (Greensand) PLANT
Background – process flow diagram
KMn0
4
PAC
L PA
CL
Orth
opho
spha
te
NaO
Cl
NaF
NaO
H
NaO
Cl
NaO
Cl
MTP Bypass
Tifft Water Supply Symposium
Water quality characterization – Raw water
Raw water quality 2010 - 2012 Avg. raw water quality 6 months pre / post 2011 storms Time Frame pH
Turbidity (NTU)
Alkalinity (mg/L as CaCO3)
Color (pcu)
Mn (mg/L)
February 2011 - August 2011 7.3 2.26 50 33 1.39
September 2011 - February 2012 7.4 3.87 50 36 2.81
Parameter 2010 2011 2012 Avg. Turbidity (NTU) 2.05 3.20 2.77 2.67
Color (pcu) 30 34 55 40
Alkalinity (mg/L as CaCO3) 53 51 60 55
Manganese (mg/L) 1.15 1.90 1.74 1.60
TOC (mg/L) 5.42 6.48 5.66 5.85
Tifft Water Supply Symposium
Water quality characterization – Plant water
Plant water - Mn and Fe (10/04/12)
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
Mn
and
Fe (m
g/L)
Sample Location
Total Mn Dissolved Mn Total Fe (Resuspended) Dissolved Fe
Tifft Water Supply Symposium
Water quality characterization – Plant water
Plant water – ATP and HPC (10/04/12)
0
50
100
150
200
250
300
350
400
1
10
100
1,000
10,000
100,000
1,000,000
10,000,000
100,000,000
HPC
(cfu
/mL)
ATP
(cel
ls/m
L)
Sample Location
ATP (Unfiltered) HPC
Tifft Water Supply Symposium
Filter biofouling
Plant water - ATP Data (February-May 2014)
1
10
100
1,000
10,000
100,000
1,000,000
10,000,000
100,000,000
ATP
(cel
ls/m
L)
Date
Raw
Sand Filter Feed
Sand Filter Discharge
Finished Water (Pump-out)
Tifft Water Supply Symposium
Filter biofouling
Sand filter media ATP data (March 2013 – March 2014)
0
1,000,000
2,000,000
3,000,000
4,000,000
5,000,000
6,000,000
7,000,000
8,000,000
9,000,000
1 2 3
ATP
(cel
ls/m
L)
Sampling Event
Sand Filter FeedSand Filter Media No. 1Sand Filter Media No. 2Sand Filter Discharge
Tifft Water Supply Symposium
Bench-scale testing
• Testing objectives – Evaluate alternative coagulants – Optimize coagulant dosage – Optimize pH – Evaluate coagulant aid polymers – Evaluate ferrate
• Parameters analyzed
– Settled and filtered water turbidity – UV-254 absorbance – Filterability index – Trihalomethane (THMFP) and Haloacetic acid
formation potential (HAAFP)
Tifft Water Supply Symposium
Bench-scale testing - ferrate
• Ferrate is a supercharged iron molecule in which iron is in the plus six oxidation state – In aqueous solution ferrate can act as an oxidant, coagulant, and
disinfectant – Unstable at neutral pH and must be produced on site
• Ferrate Treatment Technologies, LLC performed testing
Ferrate testing results
Ferrate Dose (mg/L)
Residual Iron (mg/L)
Relative Turbidity(1)
(NTU) Filterability
Index UV-254 (cm-1)
Filtered(1) THMFP (ug/L)
HAAFP (ug/L)
Filtered(2)
Raw Water 0.03 8.98 1.7 0.122 306.2 250.8
2 0.52 5.95 1.8 0.044 160.2 160.1
4 0.61 6.06 1.4 0.023 130.2 226.7
5 2.5 6.79 3.7 0.085 172 167.3 (1)Measured by a spectrophotometer; does not represent true turbidity values. (2)Filtered through 5.0 micron nylon membrane filter.
Tifft Water Supply Symposium
Bench-scale testing - summary
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
0.20
UV-
254
Abso
rban
ce (c
m-1
)
Treatment
SETTLED FILTERED
Tifft Water Supply Symposium
Bench-scale testing
Ranking
Treatment
Weighting Factor
Overall Rank 20% 20% 20% 40%
Turbidity Filterability Index UV-254 Capital and
O&M Cost
PCH182=80 mg/L 2 2 6 1 1
FS=70 mg/L l pH=No Adj. 6 4 4 2 2
PCH182=80 mg/L l pH=6.5 3 5 5 3 3
FS=70 mg/L l pH=6.0 5 3 3 4 4
Ferrate=4 mg/L 1 1 1 7 5
FS=70 mg/L l pH=6.0 l Cat. Polym.=0.2 mg/L 4 6 2 5 6
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Plant improvements - Operational
1. Monitor raw water and CLFP water quality
2. Monitor filter performance and biomass accumulation
3. Examine potential sources of fouling • intake areas, piping, and sediment levels within the reservoir
4. Dose KMnO4 based on raw water Mn concentrations, Fe concentrations, and demand from TOC; rather than KMnO4 residual
5. Routinely assess concentrations and forms (particulate, colloidal, dissolved) of Mn across treatment processes to determine the effectiveness of Mn removal
Tifft Water Supply Symposium
Plant improvements – Capital
1. Further investigate installation of a multi inlet raw water intake
2. Disinfect upstream of filtration to control bio-growth • ClO2 - demonstration testing • Cl2 - bench-scale testing
3. Consider alternate sources (New York City supplies) of raw water supply
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www.ghd.com
Questions?
Please contact Clayton Johnson at clayt.johnson@ghd.com
Tifft Water Supply Symposium
Bench-scale testing
Coagulants screened
Coagulant Name Specific Gravity
Percent Active
Ingredient pH Coagulant Type Coagulant Manufacturer
PCH 182(1) 1.26 100% 2.6 High Basicity PACL Holland Company, Inc.
SternPac 1.23 100% 2.6 Medium Basicity PACL Kemira
Aluminum Chlorohydrate 1.30 100% 2.6
High Basicity/High Aluminum PACL Kemira
Aluminum Sulfate 1.34 48% 3.5 Alum Kemira
Ferric Sulfate 1.55 60% 1.5 Iron Salt Kemira
Ferric Chloride 1.43 40% 1.5 Iron Salt Kemira
(1)Current coagulant used at the CLFP
Jar Testing Procedure
Rapid Mix RPM = 300
Duration (sec.) = 30
Flocculation RPM = 40/30/15
Duration (min.) = 5/5/5
Settling RPM = 0
Duration (min.) = 10
Tifft Water Supply Symposium
Bench-scale testing
Optimized jar testing results
Coagulant Coagulant
Dosage (mg/L) Target
pH pH
Turbidity (NTU) Filterability
Index Settled Filtered(2)
Raw Water - - 7.7 2.84 3.6
PCH 182 80 6.5 6.7 0.67 0.12 5.6
Ferric Sulfate-Cationic Polymer(1) 70 6.0 6.2 0.66 0.05 5.8
(1)CAP dosage = 0.2 mg/L
(2)Filtered through 5.0 micron nylon membrane filter.
(3)Raw Water DOC = 5.9
(4)Performed on 5.0 micron filtered samples
Coagulant Coagulant
Dosage (mg/L) Target
pH
UV-254 (cm-1)
Filtered(2)
TOC (mg/L) THMFP (ug/L)
HAAFP (ug/L) Settled Filtered(2)
Raw Water - - 0.180 6(3) 350 421
PCH 182 80 6.5 0.051 2.6 3.1 120(4) 98(4)
Ferric Sulfate-Cationic Polymer(1) 70 6.0 0.035 3.4 2.3 89(4) 60(4)
(1)CAP dosage = 0.2 mg/L
(2)Filtered through 5.0 micron nylon membrane filter.
(3)Raw Water DOC = 5.9
(4)Performed on 5.0 micron filtered samples
Tifft Water Supply Symposium
Bench-scale testing - summary
0.00
0.50
1.00
1.50
2.00
2.50
3.00
Turb
idity
(NTU
)
Treatment
SETTLED FILTERED
Tifft Water Supply Symposium
Bench-scale testing Summary results
Treatment Temp.
(oC)
pH
Turbidity (NTU)
Filterability Index
UV-254 (cm-1) Filtered(1) Settled Filtered(1)
Raw Water 8.9 7.7 2.84 3.6 0.180
Ferrate=4 mg/L - 10.94 (3) (3) 1.4 0.023
PCH182=80 mg/L 11.8 7.4 0.65 0.08 3.2 0.061
PCH182=80 mg/L l pH=6.5 11.6 6.7 0.67 0.12 5.1 0.051
FS=70 mg/L l pH=No Adj. 11.3 6.4 1.34 0.19 3.6 0.047
FS=70 mg/L l pH=6.0 10.9 6.0 1.18 0.16 3.4 0.042
FS=70 mg/L l pH=6.0 l Cat. Polym.=0.2 mg/L 13.3 6.2 0.66 0.05 5.8 0.035 (1)Filtered through 5.0 micron nylon membrane filter.
(2)pH adjusted with ferric iron.
(3)Not reported due to inaccurate method used for measurement.
Ranking
Treatment
Weighting Factor
20% 20% 20% 40% Overall Rank
Turbidity Filterability Index
UV-254 Filtered
Capital and O&M Cost
PCH182=80 mg/L 2 2 6 1 1
FS=70 mg/L l pH=No Adj. 6 4 4 2 2
PCH182=80 mg/L l pH=6.5 3 5 5 3 3
FS=70 mg/L l pH=6.0 5 3 3 4 4
Ferrate=4 mg/L 1 1 1 7 5
FS=70 mg/L l pH=6.0 l Cat. Polym.=0.2 mg/L 4 6 2 5 6
Recommended