1,4-dioxane occurrence in the haw river and in pittsboro drinking water catalina lopez velandia, mei...
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1,4-Dioxane Occurrence in the Haw River and in Pittsboro Drinking Water
Catalina Lopez Velandia, Mei Sun, and Detlef Knappe ([email protected])
Pittsboro, NC, September 28, 2015
Presentation Overview
• What is 1,4-dioxane?• 1,4-dioxane occurrence in– Pittsboro source water (Haw River at Bynum)– Pittsboro drinking water
• 1,4-dioxane sources• Conclusions
What is 1,4-dioxane?
• 1,4-dioxane dioxin
• Uses and potential sources of 1,4-dioxane– Solvent stabilizer (phased out)– Industrial solvent (textile, paper, specialty chemicals)– By-product of manufacturing processes involving
ethylene oxide (polyester, PET, detergents, cosmetics)
1,4-Dioxane – Background Information
• Miscible in water• Very difficult to remove from water• Monitored nationwide in drinking water as
part of EPA’s 3rd Unregulated Contaminant Monitoring Rule (UCMR3)– Finished drinking water samples only– Public water systems serving >10,000 people
5
32
19
21
2 4
2
4 1
1
1 1
• 28,702 drinking water samples analyzed for 1,4-dioxane• 3,350 (11.7%) had detectable levels of 1,4-dioxane• 897 (3.1%) had 1,4-dioxane levels ≥0.35 mg/L
Drinking water samples with 1,4-dioxane ≥3.5 µg/L (UCMR3 data as of May 2015)
Blue: ground water Green: surface water
1,4-dioxane cancer risk
• Likely human carcinogen (EPA IRIS database)• Lifetime consumption of drinking water
containing– 0.35 mg/L = 1:1,000,000 excess cancer risk– 3.5 mg/L = 1:100,000 excess cancer risk– 35 mg/L = 1:10,000 excess cancer risk
• Comparison with disinfection by-products– Bromodichloromethane: 0.6 mg/L = 1:1,000,000 risk– Dibromochloromethane: 0.4 mg/L = 1:1,000,000 risk
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
1,4-Dioxane Concentrations in Haw River at Bynum
10/18/14 12/7/14 1/26/15 3/17/15 5/6/15 6/25/15 8/14/150
10
20
30
40
50
60
70
Sampling Date
1,4-
Dio
xane
Con
cent
ratio
n (m
g/L)
Average: 16.3 mg/LMin: 1.6 mg/LMax: 65.8 mg/L
3/17/15 3/24/15 3/31/15 4/7/15 4/14/15 4/21/15 4/28/150
5
10
15
20
25
30
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
9,000
Raw water Finished waterFlow
Date
1,4
-Dio
xane
Con
cent
ratio
n (m
g/L)
Haw
Riv
er F
low
at B
ynum
(cfs
)
1,4-Dioxane Concentrations in Raw and Finished Pittsboro Drinking Water
Avg. raw: 7.4 mg/LAvg. finished: 6.8 mg/L
Max. raw: 24 mg/LMax. finished: 20 mg/L
1,4-Dioxane Mass Flow: Haw River at Bynum
3/16/15 3/23/15 3/30/15 4/6/15 4/13/15 4/20/15 4/27/150
100
200
300
400
500
600
Sampling Date
1,4-
Dio
xane
Mas
s Fl
ow (l
b/d)
Source Identification: Haw RiverDate
Upstream Concentration (µg/L)
Downstream Concentration (µg/L)
Oct-14 0.60 77Dec-14 0.16 123Jan-15 0.20 1.0Feb-15 0.20 76Mar-15 <0.15 3.8Apr-15 0.15 27May-15 0.20 26Jun-15 <0.15 40Jul-15 0.25 270
Aug-15 0.20 86
WWTP Discharge
Sampling Point
Source Identification: S. Buffalo Creek
Date
Upstream Concentration
(µg/L)
Downstream Concentration
(µg/L)Oct-14 0.2 4.8Dec-14 2.0 38Jan-15 0.9 226Feb-15 3.7 11Mar-15 1.8 436Apr-15 1.9 30May-15 3.8 20Jun-15 3.6 62Jul-15 0.43 22
Aug-15 0.45 14
WWTP Discharge
Sampling Point
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).
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 at Pittsboro:– Source water (Oct. 14 – Aug. 15): 16.3 mg/L (avg.),
66 mg/L (max.)– Finished water (March 15 – April 15): 6.8 mg/L (avg.),
20 mg/L (max.)– No measurable removal of 1,4-dioxane in water treatment
plant (March 15 – April 15)• NC surface water quality standard of 0.35 mg/L
greatly exceeded at Pittsboro water intake
Acknowledgments• Students in the Knappe research group: 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
Source Identification:Deep River
NCSU24-Downstream WWTPDate Concentration (µg/L)
Oct-14 254Dec-14 1405Jan-15 177Feb-15 152Mar-15 495Apr-15 844
NCSU25 - Upstream WWTPDate Concentration (µg/L)
Oct-14 1.5Dec-14 2.0Jan-15 0.7Feb-15 1.7Mar-15 2.5Apr-15 4.5
NCSU23-Downstream WWTPDate Concentration (µg/L)
Oct-14 29Dec-14 69Jan-15 47Feb-15 78Mar-15 41Apr-15 8.6
WWTP
NCSU24
NCSU23
NCSU25
3/16/15 3/23/15 3/30/15 4/6/15 4/13/15 4/20/15 4/27/150
1
2
3
4
5
6
0
2,000
4,000
6,000
8,000
10,000
12,000
14,000
Raw water Finished WaterFlow Jordan Lake Outflow
Date
1,4-
Diox
ane
Conc
entr
ation
(mg/
L)
Flow
(cfs
)
1,4-Dioxane Concentrations in Raw and Finished Fayetteville Drinking Water
Avg. raw: 2.8 mg/LAvg. finished: 2.6 mg/L
Max. raw: 5.3 mg/LMax. finished: 4.6 mg/L
1,4-Dioxane Concentrations in Raw and Finished Wilmington Drinking Water
4/15/15 4/16/15 4/17/15 4/18/15 4/19/15 4/20/15 4/21/15 4/22/150.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0
2,000
4,000
6,000
8,000
10,000
12,000Raw WaterFinished WaterFlow
Date
1,4-
Diox
ane
Conc
entr
ation
mg/
L
Cape
Fea
r Riv
er F
low
at L
&D
#1 (c
fs)
Avg. raw: 2.7 mg/LAvg. finished: 1.0 mg/L
Max. raw: 3.8 mg/LMax. finished: 1.3 mg/L
1,4-Dioxane Mass Flows: Pittsboro, Fayetteville, and Wilmington
3/16/15 3/23/15 3/30/15 4/6/15 4/13/15 4/20/15 4/27/151
10
100
1000PittsboroFayettevilleWilmington
Date
1,4-
Diox
ane
Mas
s Flo
w (l
b/d)