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 (knappe@ncsu.edu)

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

• 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

Sampling Date

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

Raw water Finished waterFlow

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

Sampling Date

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

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

NCSU24

NCSU23

NCSU25

3/16/15 3/23/15 3/30/15 4/6/15 4/13/15 4/20/15 4/27/150

10,000

12,000

14,000

Raw water Finished WaterFlow Jordan Lake Outflow

1,4-Dioxane Concentrations in Raw and Finished Fayetteville Drinking Water

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

10,000

12,000Raw WaterFinished WaterFlow

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

1000PittsboroFayettevilleWilmington

1,4-Dioxane Occurrence in the Haw River and in Pittsboro Drinking Water Catalina Lopez Velandia, Mei...

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