Village of Skaneateles Cyanotoxin Treatment Evaluation. Edwin C. Tifft Jr. Water Supply Symposium Erica Goldin September 20, 2018

Transcription

1 Village of Skaneateles Cyanotoxin Treatment Evaluation Edwin C. Tifft Jr. Water Supply Symposium Erica Goldin September 20, 2018

2 Outline Village of Skaneateles Water System Emerging Contaminants - Cyanotoxins Recent Detections in Skaneateles Lake Village of Skaneateles Response Treatment Technologies Screening Treatment Technologies Evaluation Recommendations 2

3 Village of Skaneateles Water System 3

4 Village of Skaneateles Water System 4

5 Blue Green Algae Cyanobacteria and Microcystin Toxin Blue Green Algae are actually cyanobacteria Blooms can vary significantly each year based on environmental factors 5

6 Blue Green Algae Cyanobacteria and Microcystin Toxin Intracellular vs. extracellular cyanotoxins 60 90% intracellular There are many types of cyanotoxins - microcystin being one of the most toxic and most persistent 6

7 Blue Green Algae Cyanobacteria and Microcystin Toxin No regulations USEPA microcystin health advisory limit 0.3 μg/l (children <6 and other vulnerable populations) 1.6 μg/l adults Based on 10-day exposure EPA has included cyanotoxins on its Contaminant Candidate List 4 (CCL4) WHO recommended microcystin guideline of 1.0 μg/l 7

8 Skaneateles Lake Detections 2017 Sample Location Number of Days Detected Minimum Level Detected (μg/l) Maximum Level Detected (μg/l) Average Level Detected (μg/l) Intake No Intake No Gatehouse Wet Well No Gatehouse Wet Well No. 2/ Village Pump Station 0 ND ND ND Elbridge UV plant City s Westcott Reservoir incoming City s Westcott Reservoir outgoing to Syracuse City s Woodland Reservoir incoming City s Woodland Reservoir outgoing to Syracuse 0 ND ND ND 0 ND ND ND 0 ND ND ND 0 ND ND ND Skaneateles High School 0 ND ND ND Byrne Dairy, Skaneateles 0 ND ND ND Elbridge - North 0 ND ND ND Jordan Town Hall 0 ND ND ND Syracuse - Burnet & Thompson 0 ND ND ND 8

9 Skaneateles Lake Detections Village Response Website updates (daily monitoring results) Public meeting September 2017 Presentation by GHD regarding options Treatment technology screening Treatment alternative evaluation Goal: Temporary or permanent treatment system in place by summer

10 Technology Screening Review of Treatment Options Treatment Alternatives Coagulation/sedimentation/filtration Dissolved Air Flotation (DAF) Membrane filtration (microfiltration or ultrafiltration) Chlorination Potassium Permanganate Powder Activated Carbon (PAC) Granular Activated Carbon (GAC) Ozone Ultraviolet Advanced Oxidation (UVAO) Membrane filtration (reverse osmosis or nanofiltration) Non-Treatment Alternatives Replacement Water Supply Intake Extension Watershed Protection 10

11 Chlorination Theoretical Effective CT for Treating Microcystin Using Free Chlorine Reference: Water Treatment Optimization for Cyanotoxins, Version 1.0. Ground Water and Drinking Water, United States Department of Environmental Protection, Oct. 2016, 11

12 Chlorination Involves Advantages Disadvantages Chlorine storage Contact time Operational adjustments Village receives prechlorinated water from City Existing backup feed system Lower cost alternative Variability of cyanotoxins concentrations Increased disinfection byproducts Impact on fire flow 12

13 Chlorination Fire Flow Impact of Operational Adjustments 46% decrease in available fire flow 13

14 Granular Activated Carbon Contactors Removal technology GAC is a granular adsorbent Commonly used in drinking water plants Effective treatment method 14

15 Granular Activated Carbon Contactors Involves Advantages Disadvantages Carbon contactors Empty Bed Contact Time (EBCT) Chlorine storage Building addition Equalization basin Removes cyanotoxins and cyanobacteria No disinfection byproducts Potential for expansion to provide filtration Removes incoming free chlorine residual Generates backwash waste High capital cost 15

16 Granular Activated Carbon Contactors 16

17 Granular Activated Carbon Contactors Regulatory Requirements Rapid small scale column tests (RSSCTs) On-site pilot demonstration Operator Requirements Grade IIA operator and assistant operator 17

18 Ultraviolet Advanced Oxidation Destruction technology Hydrogen peroxide combined with high intensity UV light Involves Advantages Disadvantages Hydrogen peroxide storage and feed system Chlorine storage UV reactors Building addition Chemical unloading pad Familiar technology No waste stream High life cycle cost Energy intensive Hazardous chemicals Limited full scale experience Unknown byproducts 18

19 Ultraviolet Advanced Oxidation 19

20 Ultraviolet Advanced Oxidation Regulatory Requirements On-site pilot demonstration Full-scale demonstration - TBD Operator Requirements Grade IIB operator 20

21 Replacement Water Supply Provide 2 MGD from the Onondaga County Water Authority (OCWA) Otisco Lake Water Treatment Plant Involves Advantages Disadvantages New pump station Approximately 4.5 miles of 16-inch DIP Microcystin does not enter the distribution system No on-site treatment No waste stream produce High life cycle cost Capital costs Purchasing water Operation and maintenance both within and outside municipal boundary 21

22 Replacement Water Supply 22

23 Cost Analysis Capital Costs Engineering/Legal/Administration Costs Annual Operation and Maintenance Costs Maintenance Costs Operator Costs Chemical Costs Water Purchase Costs Power Costs Heating Costs Insurance Costs Present-Worth Operation and Maintenance Costs Based on a 20-year planning period Based on a 2 percent interest rate Total 20-Year Present-Worth Cost = Capital Cost + Engineering/Legal/Administration Cost + 20-Year Present Worth O&M Cost 23

24 Opinion of Probable Costs (1) Based on an effective interest rate of 2.0 percent. (2) Excludes cost of taxes for Replacement Water Supply alternative. 24

25 Recommendations Short-Term Solution (2018 algae bloom season) Chlorination Long-Term Solution (2019 algae bloom season and on) Dependent on 2018 results monitoring results Pilot GAC system 25

26 Questions Erica Goldin

27