Surface Water Purchase from the City of Santa Cruz Water Department - - PowerPoint PPT Presentation

Surface Water Purchase from the City of Santa Cruz Water Department

July 17, 2018

ATTACHMENT 1 - ITEM 6.2

Our Project Partners and Team

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Community Water Plan

• Maximizing Conservation
• Groundwater Management
• New Water Supplies

– Water Reuse – River Water Transfers/Purchase – Desalination – Stormwater Capture

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District’s Guiding Principles for River Water Purchase/ Transfer:

• Increase public education and outreach that the District is evaluating river water

transfers for the two different options: The North Coast Option (short-term) and the San Lorenzo River Option (long-term) which the City of Santa Cruz is currently evaluating based on their water supply advisory committee efforts.

• Continue working with the City of Santa Cruz on the North Coast Option (5-year,

short-term pilot project) to investigate and resolve potential issues related to water quality and blending of groundwater and river water within the District’s

• system. Amend the District’s Domestic Water Supply permit from the Division of

Drinking Water to add the City of Santa Cruz’s surface water as a supply source.

• Ready to receive City water by December 2018.
• Continue working with the City to better understand the benefits, issues, and

constraints of the City’s long-term San Lorenzo River Option that includes in-lieu recharge with dry-summer groundwater returns and aquifer storage and recovery.

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Cooperative Water Transfer Pilot Project Agreement (excerpt)

for Groundwater Recharge and Water Resource Management (August 1, 2016-December 31, 2020)

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City’s North Coast Sources

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City’s North Coast Sources

Laguna Creek 2-25-18 Liddell Creek 3-4-18 Majors Creek 3-4-18 Included in CEQA evaluation and Water Purchase Agreement

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What’s happened to others:

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Work completed and planned

Desktop Intertie Blending Analysis June 14, 2016 CEQA Analysis January 2016 Bench scale and Jar Testing September 2016- June 2018 Full Scale Pilot 2018-20 ~250 AFY COMPLETED COMPLETED COMPLETED PREPARING FOR NOV 2018

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Water Quality Assessment: Bench Scale and Jar Testing Results & Recommendations

Presentation by Black & Veatch Team Emily Tummons, Ph. D.

Process Specialist, Water Technology Group

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Water Quality Assessment Bench-Scale Testing Results & Recommendations

City of Santa Cruz Water Department Soquel Creek Water District

17 July 2018 ATTACHMENT 1 - ITEM 6.2

Agenda

• Goals / Overview
• Testing Design
• Testing Results
• Conclusions / Recommendations
• Next Steps – Implementation Plan

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Goals/Overview

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New Water Source

The District is planning to purchase water from the City during winter months (Nov-Mar). District = Soquel Creek Water District; City = City of Santa Cruz Water Department

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DISTRICT CITY SERVICE AREA 1 SERVICE AREA 2 SERVICE AREA 3 CITY1 PARAMETER AVERAGE RANGE AVERAGE RANGE AVERAGE RANGE AVERAGE RANGE Alkalinity 196 157-254 242 197-288 175 149-205 131 92-194 Calcium 72 34-110 38 21-59 29 14-36 50 48-51 Chloride 49 25-88 41 31-53 26 18-39 25 19-30 Magnesium 21 14-25 29 16 - 50 31 21-40 9 9 - 10 CCPP2 7 5

• 1
• 7

Orthophosphate (as P) 0.02 ND-.075 0.04 ND-.09 0.2 0.15-0.34 0.2 0.1-0.3 pH 7.5 7.0–8.1 7.6 7.1-8.1 7.7 7.2-8.1 7.4 7.1-7.7 Sulfate 101 42-180 68 46-99 28 15-43 77 64-92 CSMR3 0.5 0.6 0.9 0.3 Total Dissolved Solids 477 300-638 411 332-492 282 191-357 262 255-258

1 Data from SS 105,119, or GHWTP effluent as available 2 Calcium Carbonate Precipitation Potential (CCPP) results using Water!Pro modeling software. Results modeled for

average conditions only

3 Chloride to Sulfate Mass Ratio

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Goals of Bench-Scale Corrosion Testing

• Examine the relative aggressiveness of the City’s water and the District’s

water towards materials in the District’s system.

• Screen multiple treatment conditions to determine the impact of adjusting

the water chemistry of either the District’s wells, or of the City’s water at the intertie location.

• Establish the need for future pipe-loop testing, and which treatment

alternatives could be further tested with pipe-loop testing.

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ATTACHMENT 1 - ITEM 6.2

Bench-Scale Corrosion Testing Overview

Testing Components:

• Phase 1
• Metal wire testing
• Phase 2
• Scale analysis
• Metal coupon testing

Testing Performed by:

• Virginia Tech
• Min Tang, Ph.D
• Jeffrey Parks, Ph.D
• Marc Edwards, Ph.D

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Pipe Coupon Testing Design

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Material Selection – Coupon Testing

• Harvested from the District’s system:
• Galvanized iron service lines
• 4 inch diameter asbestos cement (AC) pipe
• New copper pipe with 50:50 lead:tin solder

Selected for highest potential to release metals as a result of changes in water chemistry

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Galvanized Iron Pipe Coupons

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2nd Batch 1st Batch 170 GIP coupons

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Galvanized Iron Pipe Scale Characterization

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XRF-Mass Percent (%) Element Fe Mn Zn Pb Ti W Ni Bi Pipe 1 3.50 0.99 0.04 0.02 ND ND 0.01 0.02 Pipe 2 27.15 44.61 24.64 1.21 ND 2.39 ND ND Pipe 3 14.05 55.05 27.16 0.91 0.43 2.40 ND ND

Pipe 1 Pipe 2 Pipe 3

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Coupon Jars

• 127 Galvanized Iron Pipe Coupons
• 56 Cement Pipe Coupons
• 60 Copper Pipe with Lead Solder Coupons

Used for conditioning prior to selection for testing.

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Galvanized Iron Asbestos Cement Copper Pipe/ Lead Solder

ATTACHMENT 1 - ITEM 6.2

Conditioning

Measured metals, calcium, and/or turbidity for different coupon types. Purpose:

• Allows scale to re-equilibrate after

harvesting

• Provides baseline for testing
• Allows for selection of similar coupons

Method:

• Jars filled with District’s GW at pH 7.5
• Water exchanged 3x/week
• Length of conditioning:
• 6 weeks for galvanized iron coupons
• 3 weeks for cement and copper

pipe/lead solder coupons

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Water Treatment Condition Selection

GW = groundwater (District) SW = surface water (City) P = phosphorous

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WATER CONDITION WATER DESCRIPTION C1 GW, pH 7.5, 0.5 mg/L free chlorine (Baseline) C2 GW, pH 7.5, 0.2 mg/L orthophosphate as P, 0.5 mg/L free chlorine C3 SW, pH 7.2, 0.2 mg/L orthophosphate as P, 1 mg/L free chlorine C4 SW, pH 7.8, 0.2 mg/L orthophosphate as P, 1 mg/L free chlorine C5 Alternating between C1 and C3 C6 Alternating between C1 and C4 C7 Alternating between C2 and C3

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Testing Schedule

• 13 weeks of testing
• Alternating conditions switched

sources 1x/month

• Nomenclature:
• GW = groundwater (District)
• SW = surface water (City)
• OP = orthophosphate (0.2 mg/L as P)
• Number = pH value

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Testing Condition Weeks 0-5 Weeks 6-9 Weeks 10-13 C1 GW-7.5 GW-7.5 GW-7.5 C2 GW-7.5-OP GW-7.5-OP GW-7.5-OP C3 SW-7.2-OP SW-7.2-OP SW-7.2-OP C4 SW-7.8-OP SW-7.8-OP SW-7.8-OP C5 SW-7.2-OP GW-7.5 SW-7.2-OP C6 SW-7.8-OP GW-7.5 SW-7.8-OP C7 SW-7.2-OP GW-7.5-OP SW-7.2-OP

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Pipe Coupon Results

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Results Organization

• Asbestos cement
• Copper pipe with lead solder
• Galvanized iron

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Control Jars with Epoxy Only

Control analyte measurements taken after 2 days stagnation

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Control 1 (GW-7.5) Control 2 (GW-7.5-OP) Control 3 (SW-7.2-OP) Control 4 (SW-7.8-OP)

ATTACHMENT 1 - ITEM 6.2

Alternating Sources SW SW GW SW SW GW SW SW GW

20 40 60 80 100 120 Calcium (mg/L)

Week 0_Control Week 0 Week 4_Control Week 4 Week5_Control Week 5 Week6_Control Week 6 Week8_Control Week 8 Week9_Control Week 9 Week10_Control Week 10 Week 12_Control Week 12 Week 13_Control Week 13

Calcium

Testing shows no concern for calcium scale dissociation

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Asbestos Cement

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Alternating Sources SW SW GW SW SW GW SW SW GW

50 100 150 200 250 300 Phosphorus (µg/L)

Week 0_Control Week 0 Week 4_Control Week 4 Week5_Control Week 5 Week6_Control Week 6 Week8_Control Week8 Week9_Control Week 9 Week10_Control Week 10 Week 12_Control Week 12 Week 13_Control Week 13

Phosphorous

Minimal to no uptake of phosphorous

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Asbestos Cement

Detection Limit = 10 µg/L

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Summary for Asbestos Cement Testing

• Overall no concern for switching sources
• Calcium levels fluctuate naturally in the GW (~60 to 110 mg/L)
• SW has slightly lower calcium levels (~40 to 60 mg/L)
• Testing shows no concern for calcium scale dissociation
• Minimal to no uptake of phosphorous

SW = surface water (City); GW = groundwater (District)

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Alternating Sources SW GW SW SW GW SW SW GW SW

Copper

Minimal changes in Cu except for a spike in C6

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Copper Pipe/ Lead Solder

500 1,000 1,500 2,000 2,500 Copper (µg/L) Conditioning Week 0 Week 4 Week 5 Week 6 Week 8 Week 9 Week 10 Week 12 Week 13

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Alternating Sources SW GW SW SW GW SW GW SW

Lead

Lead decreased for all conditions except C6 Orthophosphate limited lead release

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Copper Pipe/ Lead Solder

10 20 30 40 50 60 70 80 90 100 Lead (µg/L) Conditioning Week 0 Week 4 Week 5 Week 6 Week 8 Week 9 Week 10 Week 12 Week 13

SW

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Phosphorous

Minimal to no uptake of phosphorous

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Copper Pipe/ Lead Solder

50 100 150 200 250 300 Phosphorus (µg/L) Week 0_Control Week 0 Week 4_Control Week 4 Week5_Control Week 5 Week6_Control Week 6 Week8_Control Week 8 Week9_Control Week 9 Week10_Control Week 10 Week 12_Control Week 12 Week 13_Control Week 13

Alternating Sources SW SW GW SW SW GW SW SW GW

Detection Limit = 10 µg/L

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Summary for Lead & Copper Testing

• All conditions decreased Pb release except C6
• C5 and C7 were equal to or better than C1 at limiting Pb and Cu
• C6 showed spikes in Cu and Pb when switching from SW to GW
• Cu release is limited with SW 7.8 OP
• However - switching from SW 7.8 OP to GW 7.5 caused a spike in Cu release
• Minimal to no uptake of phosphorous
• Typical due to small surface area and limited demand

Pb = lead; Cu = copper; OP = orthophosphate; SW = surface water; GW = groundwater

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GW SW SW GW SW SW GW SW SW

Turbidity

Galvanized Iron

Alternating Sources

0.0 0.5 1.0 1.5 Turbidity (NTU) Conditioning Week 0 Week 4 Week 5 Week 6 Week 7 Week 8 Week 9 Week 10 Week 12 Week 13

Turbidity is similar for all conditions – lowest for C5

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SW SW GW SW SW GW SW SW GW

Manganese

Manganese decreased for all conditions Individual spikes are the result of one elevated coupon

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Galvanized Iron

100 200 300 400 Manganese (µg/L) Conditioning Week 0 Week 4 Week 5 Week 6 Week 8 Week 9 Week 10 Week 12 Week 13

Alternating Sources

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SW GW SW

Iron

Iron is decreasing or minimal change for all conditions except C6

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Galvanized Iron

50 100 150 200 250 Iron (µg/L) Conditioning Week 0 Week 4 Week 5 Week 6 Week 8 Week 9 Week 10

Detection Limit = 10 µg/L

Alternating Sources SW GW SW SW GW SW

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50 100 150 200 250 300 Phosphorus (µg/L)

Week 0_Control Week 0 Week 4_Control Week 4 Week5_Control Week 5 Week6_control Week 6 Week8_Control Week 8 Week 9_Control Week 9 Week10_Control Week 10 Week 12_Control Week 12 Week 13_Control Week 13

Phosphorous

Phosphorous depletion of 15-67% after 3 days exposure Phosphorous depletion decreases over time

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Galvanized Iron

Detection Limit = 10 µg/L

Alternating Sources SW SW GW SW SW GW SW SW GW

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Phosphorous Depletion Test

• Galvanized iron coupons from C1 (GW-7.5) & C3 (SW-7.2-OP)
• Jars filled with SW-7.2-OP
• 0.2 mg/L orthophosphate as Phosphorous
• 2 week test
• No adjustment to water
• Measured phosphorous every 2-3 days

Goal: Understand the phosphorous demand from galvanized iron pipe for long periods of contact time with stagnant water.

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Galvanized Iron

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20 40 60 80 100 120 140 160 180 200 220 2 4 6 8 10 12 14 16 Phosphorus (µg/L) Time (day) C1-Corrected C3-Corrected

Phosphorous Depletion Test

Phosphorous is still present after 2 weeks of stagnation with SW-7.2-OP

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Galvanized Iron

Detection Limit = 10 µg/L

60% 82%

(GW-7.5 coupons) (SW-7.2-OP coupons)

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Summary for Galvanized Iron Testing

• Phosphorous uptake decreases over time
• Phosphorous is still present after 2 weeks
• Manganese is decreasing for all conditions
• Iron is decreasing or minimal change for all conditions except C6 (SW-7.8-

OP/GW-7.5)

• Turbidity is similar for all conditions

SW = surface water (City); GW = groundwater (District); OP = orthophosphate

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Conclusions/ Recommendations

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Conclusions

OP = orthophosphate; SW = surface water; GW = groundwater

Alternating Conditions:

• C5 (SW-7.2-OP/GW-7.5) performed

better or equal to C1 (GW-7.5)

• Decreased lead & iron
• C6 (SW-7.8-OP/GW-7.5) caused lead,

copper, and iron to increase

• C7 (SW-7.2-OP/GW-7.5-OP) results were

similar to C5 but would require OP

• Adjusting SW to pH 7.8 is not beneficial
• Adding OP to GW is not necessary
• Pipe-loop testing is not necessary
• Not planning to adjust water

chemistry (pH or OP)

• Proceed with C5 at the full-scale pilot
• Monitoring is necessary
• Customer notification plan
• Flushing of distribution system

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Recommendations

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Next Steps – Implementation Plan

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Distribution System Monitoring

Necessary to provide full-scale validation to bench-scale testing results

• Monitor water quality parameters:
• Before purchasing SW – baseline
• During the addition of SW
• After returning to only GW
• Monitoring Locations:
• Sampling stations throughout the

distribution system – effect on mains

• Lead & Copper Rule sampling sites –

effect on premise plumbing and service lines

• Disinfection By-Product sample sites –

total trihalomethanes (TTHMs) and haloacetic acids

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Customer Notification Plan

Alert businesses or individuals susceptible to water quality changes (i.e., hospitals, daycare facilities, nursing homes, dialysis patients, and food or beverage production facilities).

• Options for public notification:
• Mailed flier
• Letter with billing statement
• Notice added to website
• Item addressed at board meeting
• Other
• Items to include in a notification:
• Logistics of purchasing SW
• Results of testing demonstrate

minimal to no change in water quality

• Possible changes could include slight

discoloration or turbidity

• Who to contact with

questions/concerns

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Implementation Plan

• Coordination with State Department of Drinking Water

(DDW) for permit approval and to define number and location of monitoring sites.

• Isolation area within District’s system for at least 1 year
• Implications for compliance monitoring (Lead & Copper Rule;

Disinfection By-Products)

• Intertie logistics discussion
• Short-term plans (isolated zone) and long-term plans
• Flushing is complete for isolated zone

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Phase 1 Zone

• Isolate portion of Service Area 1

(2,300 service connections)

• Generally West of Soquel Creek)
• Watermains flushed
• Water supply May-Oct:
• O’Neill Ranch Well
• Garnet Well
• Main St. Well
• Water supply Nov-April
• City of Santa Cruz North Coast

(Liddell and Majors)

• Cornwell and Pringle Tanks
• Avg. Winter Demand (Nov- April)
• Isolated area in red: 250 (AFY)
• All of SA 1: 500 AFY
• All of SA 1 & SA 2: 800 AFY

Pilot Program is focused on Water Quality NOT Quantity

ATTACHMENT 1 - ITEM 6.2

Emily N. Tummons, PhD TummonsEN@BV.com 913-458-3160

17 July 2018 ATTACHMENT 1 - ITEM 6.2