Big Valley Rancheria Corrosion Control Study

Transcription

1 Big Valley Rancheria Corrosion Control Study Funded by: EPA Region 9 RCAC is a subcontractor to the Horsley Witten Group, Inc.

2 Big Valley Rancheria Corrosion Control Study Big Valley Rancheria Sarah Ryan, Environmental Director RCAC Lee Schegg, RDS Environmental Engineer

3 Rural Community Assistance Partnership, Inc. Western Rural Community Assistance Corporation 916/ Midwest Assistance Program 952/ Southern Community Resource Group 479/ Northeast RCAP Solutions 800/ Great Lakes WSOS Community Action Commission 800/ Southeast Rural Community Assistance Project 866/ /

4 Funding The Study recounted in this presentation was funded by a Environmental Protection Agency, Region 9 Drinking Water Tribal Set-Aside Grant

5 Big Valley Rancheria Corrosion Control Study Background Water System Lead and Copper Compliance Variations

6 Location Big Valley Rancheria - Lake County, CA Tribe: Big Valley Band of Pomo Indians of the Big Valley Rancheria Serves: 38 Residences Konocti Vista Casino Motel Tribal Offices RV Park Plans: 200 more residences

7 Big Valley Rancheria Location Clear Lake Lake County

8 Big Valley Band of Pomo Indians Lakeport Clear Lake

9 Big Valley Rancheria Site Residences Casino Residences Well Water Treatment Plant

10 Original Treatment Features (2003) Potassium Permanganate Injector Ozone and Air Preparation System Iron Filters Ultraviolet Light System Multimedia Filters Carbon Filters Water Softener Chlorine Injection System External Potable Water Holding Tank Grundfos Boosterpaq Pumps Diesel Fire Pump

11 Existing Water System Schematic

12 Original Treatment Features (2003) Potassium Permanganate Injector Ozone and Air Preparation System Iron Filters Ultraviolet Light System Multimedia Filters Carbon Filters Water Softener Chlorine Injection System External Potable Water Holding Tank Grundfos Boosterpaq Pumps Diesel Fire Pump

13 Well Pump Station

14 Water Treatment Plant Building

15 Green Sand Filters in WTP Building

16 GAC Filters and Zeolite Softeners

17 Hypochlorite and Phosphate Tanks and Pumps

18 Treated Water Storage Tank

19 Distribution Pumps and Diesel Driven Fire Pump

20 Lead and Copper Rule Compliance History 2003 Plant went on line 2006 Sarah Ryan produced a report as result of lead and copper exceedances

21 Lead and Copper Rule Testing (20 Residences in Fall 2016) Copper Lead Test Site mg/l Rank Percentile ug/l Rank Percentile 500 YH YH th 570 YH YH th RF ND YH th RF th The rest of the sites are under LCR action limit.

22 Water Quality Conditions High corrosivity Constant High iron Variable High manganese Constant High hardness (Motel softens water) High CO 2 Constant High turbidity Periodic High color Periodic Taste Okay Odor Okay

23 Big Valley Rancheria Corrosion Control Study Creative Process Professional Search EPA Collaboration Contract

24 Creative Process Professional Search EPA Collaboration Contract Negotiation

25 Contract EPA Funded Investigation: $25,000 Corrosion control and quality improvement testing: Kennedy/Jenks Consultants Corrosivity Evaluation Corrosion Control Options Pilot Testing Comparison of alternatives Cost: Capital and Operations Report and Recommendations

26 Big Valley Rancheria Corrosion Control Study Bench Scale Testing Theory Methods Used Results

27 Corrosion Control Theory Water Quality Parameter Testing Plotting Milliequivalents of Cations and Anions at Various Points in System

28 Corrosion Control Options ph Elevation: Air stripping Caustic addition Inhibitors: Phosphate: Previously used 3 mg/l, 30% ortho, and 70% poly blend and other phosphate blends and dosages. Not sufficiently effective. Silicate: Too much silica with 80 mg/l in well water can inhibit iron and manganese removal at ph above 7.2

29 CO 2 Air Stripping Alternatives Type: Packed tower Diffused air Subsurface aeration Spray aeration Vacuum pressure stripping Condition: Iron fouling: Double Pumping Apparent best Storage tank: High iron settling High energy Iron fouling

30 Anticipated Testing Phosphate Blend Dosage Testing Caustic Additions

31 Actual Testing 18 Liter Capacity Tub 3.4 Liters per Minute small aquarium aerator

32 Test Instruments and Lab Equipment

33 Initial Pour Testing Raw Water 250 ml Beakers phtester 1

34 CO 2 Stripping Preliminary Testing Initial pour testing back and forth in 250 ml beakers. Pours ph

35 Diffused Air Stripper Testing 18-Liter Tubs Photo at ph 6.94 Photo at ph 7.56

36 Diffused Air Stripper Testing 18-Liter Tubs Photo at ph 7.87 Photo at ph 8.27

37 Diffused Air Stripper Testing 18-Liter Tubs Aeration: 3.4 liters/minute Blower ph: Initial minutes: minutes: minutes: minutes: 8.3

38 Caustic Additions to Elevate ph

39 Bench Scale Testing Linear polarization test method by Metal Samples Company (portable) MS 1500L data logger with 3-inch length x ¼-inch copper probes. 3-inch x ⅜-inch lead probes Electrochemical method of potential displacement ΔE/ΔI polarization resistance that provides a real-time measurement of uniform and/or pitting corrosion.

40 Bench Scale Tub Aeration and ph Testing Each Week of 4- Week Test Period

41 Copper and Lead Linear Polarization Probes

42 Lead and Copper LPR Probes in Tub Cover

43 Bench Scale LPR Test Assembly Tested Each Week after Aeration CO 2 Stripping

44 Linear Polarization Testing Each Week of CO 2 Stripped, ph Elevated Phosphate Inhibited Water

45 Corrosion Rate Readout in mils/year

46 Copper Probes Before and After

47 Lead Probes Before and After

48 Bench Scale Corrosivity Testing Week ph Existing Water Copper Corrosion Rate mils/yr ph CO 2 Stripped Water Copper Corrosion MPY Lead Rate MPY Corrosion Reduction Percent

49 Big Valley Rancheria Corrosion Control Study Solutions Interim Long Range

50 Recommended Interim Water Treatment Improvements Interim: Diffused air stripper: 60-minute detention at 130 GPM Improved iron and manganese removal: Pyrolusite media to three existing and conversion of two GAC and four Zeolite filters to pyrolusite to reduce loading rate by two-thirds.

51 Recommended Interim Water Treatment Improvements - Continued Interim: Storage tank: Sludge removal and cathodic protection Cost: $200,000 interim treatment and $300,000 wastewater treatment plant separation by containment wall ($100,000 CO 2 stripping and $100,000 improved iron removal)

52 Existing Water System Schematic

53 Interim Treatment Schematic

54 Long Range Treatment (for wastewater separation) CO 2 Stripping Water Softening by Lime with Iron- Manganese Precipitation Filtration Chlorination Phosphate Inhibitor Cost: $3 million

55 Long-Term Treatment with CO 2 Stripping

56 Long-Term Treatment Schematic

57 Faucet Replacement Alternatives An option to provide water treatment for LCR compliance possibly is removal of brass faucets. Six faucets were removed and found three high lead and copper and three from low lead and copper test residences. All faucets found to be different types of chrome-plated faucets. Copper plumbing removal from eight residences. Cost was about $15,000 each = $120,000 and more expensive than corrosion control treatment

58 Big Valley Rancheria Corrosion Control Study Lessons Learned Find the right engineer/scientist Collaboration between parties involved Obvious treatment methods aren t Importance of monitoring

59 Find The Right Engineer/Scientist Right level of expertise Civil Engineers Sanitary Engineers Firms with Engineers and Scientists Right level of experience

60 Collaboration Between Parties Involved Communication Needs Technology/Abilities Funding Education Process (Patience)

61 Obvious Treatment Methods Aren t The inclusion of treatment processes and their sequence and interaction must be based on: Sound and complete raw water data Knowledge of the water chemistry Water treatment design, construction and maintenance

62 Importance of monitoring Timely chemical adjustments and their effects on the water served through a specific monitoring program is extremely important.

63 Big Valley Rancheria Corrosion Control Study For Further Information Lee Schegg

64 Big Valley Rancheria Corrosion Control Study Questions?