A Community Under the Influence? Evaluating Potential Groundwater Under the Direct Influence (GUDI) Irfan Gehlen, P.Eng.

Transcription

1 A Community Under the Influence? Evaluating Potential Groundwater Under the Direct Influence (GUDI) Irfan Gehlen, P.Eng.

2 Outline of Presentation Source water assessment - MPA Testing - Particle Size and Distribution - Aerobic Spores - Hydrogeological Investigation - Other testing Information on Case Study

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4 MPA Test Useful laboratory tool to help identify GUDI Evolved from analysis of Giardia Developed under direction of USEPA staff in Washington State Provides quantitative risk rating Not an absolute test method

5 Some Details of an MPA Test Samples taken after heavy rainfall (greater than 50 mm in previous 7 day period) May consider sampling during start of snowmelt or irrigation season Should review need to sample during dry periods

6 Flowmeter Pressure Regulator (set to 10 psi) Constant Rate Valve Cartridge Filter

7 Testing Protocol Equipment configured to not exceed flow of 1 gpm Filter approximately 1,000 US Gallons Run water through filter for hours Ship filters with ice packs in cooler Transit time to lab should be limited to 48 hours

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9 Issues! No BC labs with significant MPA experience Nearest commercial lab with extensive testing experience is in Washington State. Expensive test. Lab charge can be up to $450 per test.

10 More Issue s Need careful planning for sampling to minimize transit time Consider border crossing issues Direct surface water influence can not be determined solely on basis of one or two MPA s Test results should be used in conjunction with other information

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12 Particle Removal Algae Diatoms Aerobic Spores 3 Log Removal (99.9%)

13 Turbidity Results River Turbidity Well Turbidity

14 Total Aerobic Spore Concentration River Spore Count Well Spore Count

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16 Case Study - Elkford, BC Coliform outbreak in summer of 2001 Initiated by vandalism at one reservoir Regular sampling; 1-2 samples/week # samples & locations increased during outbreak

17 What to do? Boil Water Advisory issued Emergency disinfection and flushing Crude methods for disinfecting water

18 Boivon Creek Elk River

19 Problem! Positive Coliform counts found throughout independent pressure zone No direct interconnection between pressure zones Attention turned to other potential sources of contamination

20 Health Region Orders Required to disinfect groundwater Advised by Health Region that wells are considered as GUDI, unless proven otherwise If GUDI, need to address Giardia and Cryptosporidium

21 Community Objection! Wells operating years No previous problems Did not want chlorination

22 Health Region Concerns Public Health Protection - Precautionary approach Walkerton influence Changes in concern with respect to shallow unconfined aquifers Without assessment, wells do not meet standards of today

23 Interim Solution District installed chlorinators in summer 2002 Initially used as secondary disinfection Assessment initiated to prove or disprove GUDI Assessment of source water completed in 2003 Final Report issued November 2003

24 Why Secondary Disinfection? Problems with Contact Time! (CT Req=12) Contact Time Water Source Watermain (min) see Note 1 Service Commercial Well 1 Existing 27 Service Commercial Well 2 Existing 13 Town Centre Well Existing 2 Option mm to Fording Dr. 21 Option mm to Fording Dr. 38 Notes 1) Contact time to first customer based on w ell pump capacity

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26 Treatment Equipment Costs Treatment Option Town Centre Service Commercial Wells Town Centre O&M Service Commercial Wells O&M Ultraviolet Disinfection System $ 250,000 $ 275,000 $ 10,000 $ 25,000 Direct Filtration System $ 500,000 $ 750,000 $ 30,000 $ 40,000 Ultra Filtration System $ 650,000 $ 1,050,000 $ 60,000 $ 80,000 Kinetico Filtration System $ 900,000 $ 1,200,000 $ 92,000 $ 180,000

27 UV Disinfection - Total Estimated Cost Implementation Option Capital Cost ($) Operation & Maintenance Cost ($) Option A Service Commercial Zone 990,000 35,000 Option B Service Commercial Zone 765,000 20,000 Option C Town Center Zone 835,000 20,000 Option D Town Center Zone 875,000 36,000

28 Hydrogeological Evaluation by Piteau Associates The Collaborating Information

29 Hydrogeological Evaluation by Piteau Associates Completed hydraulic modeling Model reported: No connection with Elk River Boivin Creek to SC Wells; 285 days Boivin Creek to TC Well; days Report concluded low risk of being GUDI

30 Boivon Creek 115 days 285 days Elk River

31 Elk River at Fernie Hydrometric Station WSC Station No. 08NK flow data is unavialable due to recording station malfunction. 600 Critical Sampling Period 500 Flow (m 3 /s) Jan 31-Jan 2-Mar 1-Apr 2-May 1-Jun 1-Jul 31-Jul 31-Aug 30-Sep 30-Oct 29-Nov 30-Dec Date

32 MPA Testing in Elkford Samples taken in August Nothing found in Town Center Well - Trace of Algae at Service Commercial Wells Both samples rated as low risk

33 MPA Testing in Elkford Samples taken in September 2002 Both samples rated as low risk All MPA testing to date has been at periods of low river level Scheduled additional samples for spring freshet

34 Summary of MPA Testing Sample Date Town Centre Service Commercial Wells Score Rating Score Rating August 27, Low Risk 4 Low Risk July 31, Low Risk 0 Low Risk May Low Risk 0 Low Risk June 16, Low Risk 0 Low Risk Notes: 1) Score and Risk Rating are as per EPA Consensus Method.

35 Testing for Aerobic Spores Looked at aerobic spore levels None to very low levels detected in surface sources Possible reasons: low water temp. low nutrient levels

36 Particle Size Testing Interested in 1-20 micron range Surface sources should contain significantly more particles than the well water (during spring freshet) Samples collected April-June 2003

37 Particle Counts (2-10 Micron Range) 120,000 * Result less than background level in pure Lab Water No. of Particles (2-10 micron range) 100,000 80,000 60,000 40,000 20,000 ** Data omitted due to lab error 0 TC Well Boivin Creek Elk River SC Well #1 SC Well #2 April 23, May 22, June 4, June 17, * * * * *

38 Turbidity Monitoring Monitor levels in surface sources and each well Drinking Water Regulations turbidity should be < 1.0 NTU

39 Turbidity Comparison Turbidity (NTU) May-03 8-Jun Jun Jul-03 7-Aug Aug Sep-03 6-Oct-03 Boivin Creek Elk River Service Commercial Well 2 Service Commercial Well 1 Town Center Well

40 Turbidity Comparison (Magnified Range) Turbidity (NTU) May-03 8-Jun Jun Jul-03 7-Aug Aug Sep-03 6-Oct-03

41 Summary of Turbidity Analysis Turbidity Data (NTU) Percentage of Samples Sample Location Total No. of Samples Maximum Average Median Minimum < 5.0 NTU < 1.0 NTU < 0.3 NTU Town Center Well % 91% 59% Boivin Creek % 51% 17% Elk River % 23% 1% Service Commercial Well % 98% 66% Service Commercial Well % 98% 62% Notes: 1) Summary table is based on data collected between June 5, 2003 to September 23, ) The spring freshet in 2003 occurred in early June for the Elkford area.

42 Microbiological Speciation Identify and test well water for bacteria commonly found in surface water Collect sample & send to lab Incubate at lab Identify types of Bacteria, Fungus or Yeast Likely habitat/comment

43 Microbiological Speciation Cost per sample; Approx. $140 Results; Available 4-5 weeks

44 MICROBIAL IDENTIFICATION Sample CFU/100cc Organisms_Identified Likely_Habitat/Comments Sample 1 8 Azomonas insignis B -soil, water 17Jun03 09:30a 4 Bacillus sphaericus B -widespread Sample 2-17Jun03 09: Pseudomonas putida B -soil, water 1600 Micrococcus luteus B -skin 2800 Arthrobacter viscosus B -soil 1200 Shewanella putrefaciens B -mud & stagnant water 1800 Hydrogenophaga pseudoflava B -soil, mud, water 600 Vibrio metschnikovii B -water 200 Vibrio proteolyticus B -saltwater, marsh 1400 Acetobacter hansenii B -plant pathogen; food spoilage 1200 Cytophaga johnsonae B -soil, freshwater 200 Nannocystis exedens B -soil, decaying vegetation, dung Sample Listonella anguillarum II B -water, fish 17Jun03 09: Alcaligenes xylosoxydans B -soil, water 3600 Pseudomonas putida biovar A B -soil, water 800 Pseudomonas putida B -soil, water 1200 Chryseobacterium balustinum B -soil and water 2000 Cytophaga johnsonae B -soil, freshwater 800 Bacillus licheniformis B -soil 400 Shewanella putrefaciens B -widespread; environment 400 Aeromonas sobria B -freshwater, sewage, fish 800 Acinetobacter calcoaceticus B -soil, water, sewage; potential pathogen Sample Sphingomonas paucimobilis B -widespread; environment; clinical isolates 17Jun03 09: Nocardioides luteus B -soil 100 Cladosporium herbarum (Pers.)Link F -saprophyte on organic debris, soil 800 Hydrogenophaga pseudoflava B -soil, mud, water 6 Cytophaga johnsonae B -soil, freshwater 68 Acetobacter hansenii B -plant pathogen; food spoilage 400 Lactobacillus viridescens B -meat spoilage; milk 8 Acidovorax delafieldii B -widespread; environment Sample Chryseobacterium indologenes B -soil, water; strong fruity odor 17Jun03 09: Pseudomonas putida B -soil, water 100 Acidovorax delafieldii B -widespread; environment 16 Bacillus mycoides B -widespread, soil, water, vegetation B = bacterium Y = yeast F = fungus CFU = colony forming units T. Winchester W. Riggs H. Hartmann Microbiologist Sr. Microbiologist Mycologist

45 Microbial Identification Results Sample Location May 22, 2003 June 18, 2003 Town Center Well None Detected None Detected Boivin Creek Potential pathogens/sewage habitat Sewage Elk River Sewage habitat Potential pathogens/sewage habitat Service Commercial Well 1 None Detected None Detected Service Commercial Well 2 None Detected None Detected Notes: 1) Cells highlighted with * indicate those samples were E-Coli was found.

46 Coliform Bacteria Analysis during spring freshet Sample Location May 23, 2003 June 3, 2003 June 18, 2003 Total Coliform Fecal Coliform Total Coliform Fecal Coliform Total Coliform Fecal Coliform Town Center Well < 1 < * < 1 < 1 Boivin Creek 3 1 < 1 < 1 3 < 1 Elk River 2 < * 40 2 * Service Commercial Well 1 < 1 < 1 < 1 < 1 < 1 < 1 Service Commercial Well 2 < 1 < 1 < 1 < 1 < 1 < 1 Notes: 1) Cells highlighted with * indicate those samples were E-Coli was found. Contaminated Sample?

47 Monitoring of Water Temperatures Manual readings taken from Elk River, Boivin Creek and each well. Also used Temp. monitoring feature on Chlorine Analyzers for wells. Data to be analyzed for trends between surface sources and groundwater

48 Temperature Data - Boivin Creek and Elk River Boivin Creek Elk River Temperature (Celcius) 10-Aug Aug-02 7-Sep Sep-02 5-Oct Oct-02 2-Nov Nov Nov Dec Dec Jan Jan-03 8-Feb Feb-03 8-Mar Mar-03 5-Apr Apr-03 3-May May May Jun Jun Jul Jul-03 9-Aug Aug-03 6-Sep Sep-03 4-Oct Oct-03

49 Temperature Data - Boivin Creek and Service Commercial Wells 12.0 Boivin Creek Service Commercial Well #2 Service Commercial Well # Temperature (Celcius) 10-Aug Aug-02 7-Sep Sep-02 5-Oct Oct-02 2-Nov Nov Nov Dec Dec Jan Jan-03 8-Feb Feb-03 8-Mar Mar-03 5-Apr Apr-03 3-May May May Jun Jun Jul Jul-03 9-Aug Aug-03 6-Sep Sep-03 4-Oct Oct-03

50 Temperature Data - Boivin Creek and Town Center Well Boivin Creek Town Center Well Temperature (Celcius) 10-Aug Aug-02 7-Sep Sep-02 5-Oct Oct-02 2-Nov Nov Nov Dec Dec Jan Jan-03 8-Feb Feb-03 8-Mar Mar-03 5-Apr Apr-03 3-May May May Jun Jun Jul Jul-03 9-Aug Aug-03 6-Sep Sep-03 4-Oct Oct-03

51 Temperature Data - Elk River and Service Commercial Wells 12.0 Elk River Service Commercial Well #2 Service Commercial Well # Temperature (Celcius) 10-Aug Aug-02 7-Sep Sep-02 5-Oct Oct-02 2-Nov Nov Nov Dec Dec Jan Jan-03 8-Feb Feb-03 8-Mar Mar-03 5-Apr Apr-03 3-May May May Jun Jun Jul Jul-03 9-Aug Aug-03 6-Sep Sep-03 4-Oct Oct-03

52 Water Temperature Results No definitive pattern found Only seasonal variation

53 Summary Elkford - Source water assessment - Key testing May to June, MPA Testing, Particle Size,Turbidity - Microbial Analysis, Coliform Testing - Water Temperature Information used in conjunction with the hydrogeological assessment

54 Recommendations Treatment for Giardia & Cryptosporidium not required Provide 4 log (99.99%) inactivation for bacteria & viruses (Precautionary approach) Assess land uses immediately north of all community wells

55 Upgrade Town Centre Well $500,000 $1,600,000

56 Discussion Similar testing may be suitable for other areas where there may be GUDI Other potential parameters: conductivity alkalinity or hardness ORP

57 Evaluating Potential Groundwater Under the Direct Influence (GUDI) Comments or Questions? Irfan Gehlen, P.Eng.