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1,4-Dioxane in North Carolina Surface Water: Occurrence Data and Regulatory Framework
Catalina Lopez Velandia, Mei Sun, and Detlef Knappe ([email protected])
WRRI Annual Conference, Raleigh, NC, March 19, 2015
Presentation Overview
• 1,4-Dioxane – background information
• National occurrence (UCMR3 data)
• Objectives
• North Carolina Occurrence
• NC Regulatory framework
• Conclusions and Future Work
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1,4-Dioxane – Background Information
• Sources– Solvent stabilizer (phased out)
– Industrial solvent
– By-product of manufacturing processes involving ethylene oxide (polyester, PET, detergents, cosmetics)
• Probable human carcinogen; one in a million excess cancer risk associated with lifetime consumption of water containing a 1,4-dioxane concentration of 0.35 mg/L (EPA IRIS database)
• Included in the 3rd Unregulated Contaminant Monitoring Rule (UCMR3)
• Miscible in water and essentially non-volatile
• Effectiveness of treatment processes
– Not removed by conventional treatment
– Very high powdered activated carbon doses and granular activated carbon use rates
– Ozone somewhat effective
– Partially removed by reverse osmosis membranes
– Among established treatment processes, advanced oxidation processes (O3/H2O2, UV/H2O2) may be the only effective treatment option
1,4-Dioxane – Background Information
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National Occurrence:UCMR3 Data
2917
13
2 3
2
41
1
1 1
Number of drinking water samples with 1,4-dioxane concentrations ≥3.5 mg/L (as of January 2015;
blue: ground water, black: surface water)
Nationwide: • 22,611 drinking water samples analyzed for 1,4-dioxane• 11.6% had detectable levels of 1,4-dioxane• 3.2% had 1,4-dioxane levels ≥0.35 mg/L
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Overall Research Objectives
• Develop sensitive and rapid analytical method for 1,4-dioxane
• Develop 1,4-dioxane occurrence data set for Cape Fear River watershed in NC to
– Identify 1,4-dioxane sources
– Establish 1,4-dioxane mass flows
– Support 1,4-dioxane exposure assessment
• Identify treatment options for 1,4-dioxane control
– Surface water treatment plants
– Point of use treatment
Overall Research Objectives
• Develop sensitive and rapid analytical method for 1,4-dioxane
• Develop 1,4-dioxane occurrence data set for Cape Fear River watershed in NC to
– Identify 1,4-dioxane sources
– Establish 1,4-dioxane mass flows
– Support 1,4-dioxane exposure assessment
• Identify treatment options for 1,4-dioxane control
– Surface water treatment plants
– Point of use treatment
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Development of Rapid Analytical Method
Analytical Method Overview
Basis:
EPA Method 522
“Determination of 1,4-dioxane in Drinking
Water by Solid Phase Extraction (SPE) and Gas Chromatography/ Mass Spectrometry (GC/MS)
with Selected Ion Monitoring (SIM)”
Major differences
- Heated purge-and-trap instead of SPE
- Selected-ion storage with ion trap MS instead of SIM with quadrupole MS
- Quantification with mass-labeled internal standard 1,4-dioxane-d8
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InstrumentationAutosampler Heated Purge and Trap Ion trap GC/MS
Calibration Curve and Method Reporting Limit
• Method reporting limit: 100 ng/L
Theoretical
Concentration
(µg/L)
Back-Calculated
Concentration
(µg/L)
Error
0.102 0.1 1.50%
0.305 0.32 4.20%
1.018 0.97 5.10%
3.054 2.99 2.20%
10.18 10.5 3.60%
30.54 33.1 8.50%
101.8 95.0 6.60%
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Matrix Spike Results: Cape Fear River water
Spiked
concentration
(µg/L)
Theoretical
Concentration
(µg/L)
Measured
Concentration (µg/L)
Average
recovery
Average*Standard
Deviation*
0 N/A 2.20 0.08
0.509 2.71 2.71 0.13 100%
2.036 4.24 3.98 0.08 87%
10.18 12.38 11.93 0.05 96%
* Three replicates per analysis
1,4-dioxane occurrence in NC
• 115 detects in 700 NC finished drinking water samples (16.4%)
• 24 out of 106 public water supply systems in NC had detects (22.6%)
• Of the 10 highest concentrations in the national UCMR3 database, 6 are NC samples
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Location WaterSource 1,4-DioxaneConcentration(mg/L)
CityofAlbemarle BadinLake,TuckertownReservoir(PeeDeeRiver)
0.09–0.4(8samplestotal,4perplant)
MontgomeryCounty LakeTillery(PeeDeeRiver) 0.35
CityofKannapolis KannapolisLake ND,ND,ND,3.1
ChathamCounty JordanLake 0.72,0.73
HarnettCounty CapeFearRiver 2.5,4.4
TownofHollySprings–HarnettCountyIntertie
CapeFearRiver(purchasedfromHarnettCounty)
1.2,1.9,4.4,5.6
TownofFuquay-Varina CapeFearRiver,NeuseRiver 2.4
CityofSanford CapeFearRiver 1.8,4.0,4.2,13
MooreCounty–EastMoore
WaterDistrictIntertie
CapeFearRiver(purchased
fromHarnettCounty)
3.9,6.6,9.2,12
FayettevillePublicWorks CapeFearRiverandGlenville
Lake
ND–8.8
(8samplestotal,4perplant,1ND)
OldNorthUtilityServices–Ft.Bragg
CapeFearRiver(purchasedfromHarnettCountyand
FayettevillePublicWorks)
1.3,2.4,4.2,4.9
CapeFearPublicUtilities
Authority–Wilmington
CapeFearRiver ND,0.38,0.52,4.7
BrunswickRegional CapeFearRiver 1.6,2.6
NC Occurrence – UCMR3 Data
Cape Fear River Watershed
50+ points in the Cape Fear River Basin, bracketing NPDES discharges and hazardous waste sites
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Field Sample Collection
Preservatives:50 mg/L sodium sulfite1 g/L sodium bisulfateAdded sequentially in the field
Brown glass bottles 500 mL with PTFE Caps
Source Identification:Deep River
NCSU24-Downstream WWTPDate Concentration (µg/L)
Oct-14 254Dec-14 1405Jan-15 177Feb-15 152
NCSU25-Upstream WWTPDate Concentration (µg/L)
Oct-14 1.5Dec-14 2.0Jan-15 0.7Feb-15 1.7
NCSU23-Downstream WWTPDate Concentration (µg/L)
Oct-14 29Dec-14 69Jan-15 47Feb-15 78
WWTP
NCSU24
NCSU23
NCSU25
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Source Identification: Haw River
NCSU44
NCSU43
WWTP
NCSU44-Upstream of WWTPDate Concentration (µg/L)
Oct-14 0.60Dec-14 0.16Jan-15 0.20Feb-15 0.20 NCSU43-Downstream of WWTP
Date Concentration (µg/L)Oct-14 77Dec-14 123Jan-15 1.0Feb-15 76
Source Identification:S. Buffalo Creek
Downstream
Upstream
WWTP
NCSU48-Upstream of WWTPDate Concentration (µg/L)
Oct-14 0.2Dec-14 2.0Jan-15 0.9Feb-15 3.7
NCSU47-Downstream of WWTP
Date Concentration (µg/L)Oct-14 4.8Dec-14 38Jan-15 226Feb-15 11
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Multiple sources;Variability in concentrations
suggests episodic releasesNCSU41 – 68 mg/L
NCSU40 – 68 mg/L
NCSU39 – 77 mg/L
NCSU37 –164 mg/L
Not every discharge represents a source; again, variability in concentrations indicates episodic releases
Example for the Haw River
Concentrations >150 mg/L in one section of river (further upstream ~70 ug/L)
Concentration <15 mg/L further downstream
NCSU37 – 164 mg/L
NCSU36 – 163 mg/L
NCSU35 – 154 mg/L
NCSU34 – 8.2 mg/L
NCSU33 – 13 mg/L
NPDES discharge
NCSU sampling point
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1,4-Dioxane mass flows
NCSU13
NCSU12
NCSU07a
Haw RiverDeep River
Station C (mg/L) MF (lb/d)
NCSU13(Deep)
7.6 3.8
NCSU12(Haw)
20.9 45.7
NCSU7a(CFR)
19.2 51.4
Station C (mg/L) MF (lb/d)
NCSU13(Deep)
11.4 10.0
NCSU12(Haw)
12.8 18.9
NCSU7a(CFR)
11.9 28.1
Cape Fear River
Regulatory Framework
• No federal drinking water standard
• No NC drinking water standard
• NC groundwater standard: 3 mg/L
• Surface water quality (in-stream) standard:
– 0.35 mg/L for streams classified as water supplies (WS-I through WS-IV)
– 80 mg/L for other stream classifications
15A NCAC 02B .0208 STANDARDS FOR TOXIC SUBSTANCES AND TEMPERATUREFor carcinogens, the concentrations of toxic substances shall not result in unacceptable health risks and shall be based on a Carcinogenic Potency Factor (CPF). An unacceptable health risk for cancer shall be considered to be more than one case of cancer per one million people exposed (10-6 risk level).
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CONCLUSIONS
• In the Cape Fear River watershed, multiple sources of 1,4-dioxane exist in the uppermost reaches of the watershed
• 1,4-dioxane concentrations in the Haw River, a drinking water source, can exceed 150 mg/L
• Conventional water treatment processes do not remove 1,4-dioxane
• For a utility employing raw and settled water ozonation, UCMR3 data showed finished water 1,4-dioxane concentration of almost 5 mg/L
Where from here?
• Stakeholder group (DENR, Fayetteville PWC, NCSU) was expanded to include utility personnel from three municipalities from where 1,4-dioxane originates
• Pretreatment program managers in the three source communities have begun/are beginning to conduct sewer trunk line studies to identify sources within sewer collection system
• In collaboration with three drinking water treatment plants, daily composite samples are being collected at three drinking water utilities to determine
– 1,4-dioxane concentrations in source and finished water
– 1,4-dioxane mass flows in source water
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Acknowledgments
• Zachary Hopkins, Harold Hounwanou, Joshua Kearns, Amie McElroy, Jonathan Moreno Barbosa
• Funding agencies– North Carolina Urban Water Consortium
– NSF RAPID;GOALIE (#1449768)
• Utility participants: Fayetteville Public Works Commission, Cape Fear Public Utilities Commission, Town of Pittsboro
• North Carolina Department of Environment and Natural Resources: Carrie Ruhlman
Wastewater percentage in Haw River at Bynum/Pittsboro
0
10
20
30
40
50
60
10
100
1000
10000
12/13/11 3/12/12 6/10/12 9/8/12 12/7/12 3/7/13 6/5/13 9/3/13 12/2/13
Pe
rce
nt
Was
tew
ate
r
Stre
amfl
ow
(M
GD
)
Streamflow at Pittsboro Percent of flow from WWTPs
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Cumulative distribution functions summarizing 1,4-dioxane occurrence in NC
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0.01 0.1 1 10 100
Frac
tio
n o
f sa
mp
les
wit
h 1
,4-D
ioxa
ne
C
on
cen
trat
ion
Le
ss T
han
Sta
ted
Val
ue
1,4-Dioxane Concentration (mg/L)
MRL: 70 ng/L
10-6 Risk: 350 ng/L
All samples (n=406)
GW samples (n=221)
SW samples (n = 184)
UCMR3 Statistics
Nationwide NC-wide
# 1,4-dioxane samples 15,084 406
# of samples with 1,4-dioxane >0.07 mg/L
1,715 (11.4%) 60 (14.8%)
# of samples with 1,4-dioxane >3.5 mg/L
503 (3.3%) 25 (6.2%)
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Chromatograph & Spectrum
Total ion count
1,4-dioxane peak
Internal standard (1,4-dioxane-d8)
peak
1,4-dioxane spectrum
1,4-dioxane-d8 spectrum
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Matrix Spike: Sample LocationCape Fear River water from William O. Huske Lock & Dam, South of Fayeteville, NC
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Jordan Lake
