Getting to Non-Detect PFOS as Quickly as Possible

Transcription

1 Getting to Non-Detect PFOS as Quickly as Possible Beth Mende, HDR Bob York, The City of Issaquah AWWA- PNWS Conference April HDR, all rights reserved.

2 Project Background Treatment Process Selection Project Timeline Operation and Maintenance Project Challenges Summary Project Construction and Costs

3 Project Background

4 History Water Supply Regional water from Cascade Water Alliance (who purchases water from Seattle Public Utilities) Groundwater totaling over 3,000 gpm (peak hour) Gilman Well No gpm Gilman Well No. 5 1,150 gpm Risdon Well No gpm Risdon Well No. 2 1,050 gpm

5 PFCs Discovered in Well No. 4

6 Perfluorinated Compound Overview Organofluorine compounds o Stable bonds Stable, nonreactive, and effective at low concentrations Hydrophobic, hydrophilic, and lipophilic all in one Highly soluble in water Adverse health effects PFOS

7 Regulatory Advisories Currently there are no enforceable federal drinking water limits for PFCs January 2009 EPA releases Provisional Health Advisories May 2016 EPA releases Lifetime Health Advisories Compound Occurrence of PFCs in Public Water Systems (PWSs) EPA Lifetime Health Advisory (LHA) Concentration (μg/l)* (2016) UCMR 3 Minimum Reporting Level (MRL) (μg/l)* % of Public (PWSs) with Results MRL* % of PWSs with Results > LHA* PFOS % 0.90% PFOA % 0.30% PFNA N/A PFHxS N/A PFHpA N/A PFBS N/A **4,864 reporting PWSs - Data from EPA UCMR 3

8 Well No. 4 Site Located adjacent to I-90 (adjacent to Issaquah Creek) Constrained site (accessed through Medical/Dental Center Parking Lot)

9 Alternatives Evaluation Evaluated series of short and long term options: Well abandonment Blending with other wells Pump to waste Treatment (Selected)

10 Treatment Process Selection

11 Treatment Process Selection Treatment Method Treatment Process Documented PFC Removal % Activated Carbon GAC or PAC PFOA > 90 PFOS > 90 PFNA > 90 Anion Exchange Special Resins PFOA - 10 to 90 PFOS > 90 PFNA - 67 Relative Treatment Cost Application $$ Surface Water, Groundwater, PWSs, Households $$ Surface Water, Groundwater Membrane Filtration RO, NF PFOA > 90 PFOS > 90 PFNA > 90 $$$ Surface Water, Groundwater, PWSs, Households (RO) Advanced Oxidation UV/H2O2 PFOA < 10 PFOS 10 to 50 PFNA < 10 $$$ Surface Water, Groundwater

12 Anion Exchange PFOS removed well by anion exchange Can partially remove PFOA, PFNA, PFOS Reject brine must be properly disposed of Costs are similar to activated carbon Rate of exchange will depend on many factors Surface water supplies may need clarification/filtration before treatment Less effective at short-chained PFC removal

13 Advanced Oxidation Processes (AOP) Can oxidize a multitude of contaminants to degradation products using reactive hydroxyl radicals Less effective at breaking down organic compounds such as PFCs No significant difference in removal of PFCs Significant energy input

14 Membrane Filtration Excellent PFC removal May be designed for under-sink or residential well water PFC treatment Can be successfully combined with GAC for higher PFC removal rates Reasonable for groundwater systems Reject water must be treated before discharging High capital expense with high energy demands Susceptible to fouling

15 Activated Carbon Widely used for PFC removal, high removal rates GAC provides better removal than PAC Useful for responding to spills and emergency treatment needs In-house options Possibility of competitive adsorption with other compounds present, such as NOM Creates waste residuals to dispose of exhausted carbon Process optimization necessary (ph, temperature, contact time) Requires thermal regeneration of GAC for complete destruction of PFC s from the environment

16 GAC Design Basis Parameter Configuration Carbon Carbon per contactor Value 2 vessels (lead/lag) Coconut 20,000 lbs Flow Rate 250 gpm (Well No. 4) Contact Time 21.4 minutes

17 Carbon Selection Two types of carbon selected o Lead Vessel - Coconut o Lag Vessel Bituminous Coal Initial estimate predicted carbon removal to be every 3 months Original carbon is still being used

18 Project Timeline

19 Project Timeline o City Council Authorization: March 2016 o Bid Documents Issued: April 2016 o Construction Began: May 2016 Slab, piping, fencing Flow meter and provisions for chemical feed Rental Vessel unloading and installation System disinfection Carbon loading and installation Initial Backwash o Treatment System Went Online: June 2016 After acceptable BAC-T and PFC Results obtained After WDOH Approval o Total Construction Time (to start-up) 77 Days Included Memorial Day Weekend Included Resampling for PFCs

20 Project Construction and Costs

21 Project Costs Installed project (design, permitting, construction) cost = $560,000 o Lease-to-buy for two 10-foot dia. vessels, including 40,000 lb. carbon 3 year lease with option to purchase o $220,000 for valving/piping/equipment slab o $30,000 for winterization and fencing GAC replacement costs o Original estimate was $240,000 per year for 3-month bed life o Current estimate is $50,000 per year $35,000 for carbon

22 Site Layout

23 Project Construction

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25 Carbon Loading o 1,000 lb. Supersacks o Prefilled bottom of each vessel with water o Contractor loaded from the top (using forklift) o Took only one day for 40,000 lb.

26 Freeze Protection o Initially considered a structure ($100K+) o Operators devised elegant alternative Custom tarps Propane heater o Cost <$15K Photo Courtesy: Shaun Kurtz, Issaquah Public Works Operations

27 Operation and Maintenance

28 Sampling and Monitoring Monitoring PFOS breakthrough o Filters have been running for 10 months with no breakthrough of PFCs through outlet of lead vessel o Lead vessel now being backwashed every 6 weeks GAC selected for future use (carbon replacement of first vessel imminent) In bed sample ports used to monitor progression of the mass transfer zone and GAC usage.

29 Current Water Quality Data Well No. 4 Raw Water Testing Results (March 2017) Well No. 4 Lead Vessel Outlet Test Results (March 2017)

30 Project Challenges

31 Site Constraints Limited site space Site Setbacks o Site located adjacent to Issaquah Creek Limited Site access o Site located in the corner of commercial parking lot.

32 Summary

33 Responding to PFOS in Drinking Water Systems Assessing Contamination o If water contain PFOA and PFOS greater than the.07 ppb concentrations, undertake additional sampling to assess the level, scope, and localized source of contamination. Informing the public o Notify state drinking water safety agency. o Execute crisis communication plan o Provide information to consumers regarding PFOA and PFOS o Provide actions that are being taken and information on alternative drinking water sources Limiting exposure o Closing contaminated wells o Providing well treatment o Access additional resources as needed

34 Acknowledgements Questions? Beth Mende, HDR Bob York, The City of Issaquah Issaquah City Council City of Issaquah Public Works Directors and Staff o Bret Heath o Sheldon Lynne o Greg Keith o Tony Nguyen o Butch Weiher o PWO Operators (Shaun, Todd, Alan) TIGG, LLC. Calgon Carbon Washington State Department of Health 2014 HDR, all rights reserved.

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