ATTACHMENT 1 - ITEM 6.2 Surface Water Purchase from the City of Santa Cruz Water Department July 17, 2018
ATTACHMENT 1 - ITEM 6.2 Our Project Partners and Team
ATTACHMENT 1 - ITEM 6.2 Community Water Plan • Maximizing Conservation • Groundwater Management • New Water Supplies – Water Reuse – River Water Transfers/Purchase – Desalination – Stormwater Capture
ATTACHMENT 1 - ITEM 6.2 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.
ATTACHMENT 1 - ITEM 6.2 Cooperative Water Transfer Pilot Project Agreement (excerpt) for Groundwater Recharge and Water Resource Management (August 1, 2016-December 31, 2020)
ATTACHMENT 1 - ITEM 6.2 City’s North Coast Sources
ATTACHMENT 1 - ITEM 6.2 City’s North Coast Sources Laguna Creek 2-25-18 Majors Creek Liddell Creek 3-4-18 3-4-18 Included in CEQA evaluation and Water Purchase Agreement
ATTACHMENT 1 - ITEM 6.2 What’s happened to others:
ATTACHMENT 1 - ITEM 6.2 Work completed and planned Bench scale and Desktop Intertie CEQA Analysis Full Scale Pilot Jar Testing Blending Analysis January 2016 2018-20 September 2016- June 14, 2016 ~250 AFY June 2018 COMPLETED COMPLETED COMPLETED PREPARING FOR NOV 2018
ATTACHMENT 1 - ITEM 6.2 Water Quality Assessment: Bench Scale and Jar Testing Results & Recommendations Presentation by Black & Veatch Team Emily Tummons, Ph. D. Process Specialist, Water Technology Group
ATTACHMENT 1 - ITEM 6.2 17 July 2018 Water Quality Assessment City of Santa Cruz Water Department Soquel Creek Water District Bench-Scale Testing Results & Recommendations
ATTACHMENT 1 - ITEM 6.2 Agenda • Goals / Overview • Testing Design • Testing Results • Conclusions / Recommendations • Next Steps – Implementation Plan 2
ATTACHMENT 1 - ITEM 6.2 Goals/Overview 3
ATTACHMENT 1 - ITEM 6.2 New Water Source DISTRICT CITY CITY 1 SERVICE AREA 1 SERVICE AREA 2 SERVICE AREA 3 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 CCPP 2 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 CSMR 3 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 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 4
ATTACHMENT 1 - ITEM 6.2 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. 5
ATTACHMENT 1 - ITEM 6.2 Bench-Scale Corrosion Testing Overview Testing Components: Testing Performed by: • Phase 1 • Virginia Tech • Metal wire testing • Min Tang, Ph.D • Phase 2 • Jeffrey Parks, Ph.D • Scale analysis • Marc Edwards, Ph.D • Metal coupon testing 6
ATTACHMENT 1 - ITEM 6.2 Pipe Coupon Testing Design 7
ATTACHMENT 1 - ITEM 6.2 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 8
ATTACHMENT 1 - ITEM 6.2 Galvanized Iron Pipe Coupons 170 GIP coupons 2 nd Batch 1 st Batch 9
ATTACHMENT 1 - ITEM 6.2 Galvanized Iron Pipe Scale Characterization 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 10
ATTACHMENT 1 - ITEM 6.2 Galvanized Iron Coupon Jars • 127 Galvanized Iron Pipe Coupons • 56 Cement Pipe Coupons • 60 Copper Pipe with Lead Solder Coupons Copper Pipe/ Asbestos Cement Lead Solder Used for conditioning prior to selection for testing. 11
ATTACHMENT 1 - ITEM 6.2 Conditioning Purpose: Method: • Allows scale to re-equilibrate after • Jars filled with District’s GW at pH 7.5 harvesting • Water exchanged 3x/week • Provides baseline for testing • Length of conditioning: • Allows for selection of similar coupons • 6 weeks for galvanized iron coupons • 3 weeks for cement and copper pipe/lead solder coupons Measured metals, calcium, and/or turbidity for different coupon types. 12
ATTACHMENT 1 - ITEM 6.2 Water Treatment Condition Selection WATER WATER DESCRIPTION CONDITION 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 GW = groundwater (District) SW = surface water (City) P = phosphorous 13
ATTACHMENT 1 - ITEM 6.2 Testing Schedule • 13 weeks of testing Testing Weeks 0-5 Weeks 6-9 Weeks 10-13 Condition • Alternating conditions switched C1 GW-7.5 GW-7.5 GW-7.5 sources 1x/month C2 GW-7.5-OP GW-7.5-OP GW-7.5-OP • Nomenclature: C3 SW-7.2-OP SW-7.2-OP SW-7.2-OP • GW = groundwater (District) C4 SW-7.8-OP SW-7.8-OP SW-7.8-OP • SW = surface water (City) C5 SW-7.2-OP GW-7.5 SW-7.2-OP • OP = orthophosphate (0.2 mg/L as P) C6 SW-7.8-OP GW-7.5 SW-7.8-OP • Number = pH value C7 SW-7.2-OP GW-7.5-OP SW-7.2-OP 14
ATTACHMENT 1 - ITEM 6.2 Pipe Coupon Results 15
ATTACHMENT 1 - ITEM 6.2 Results Organization • Asbestos cement • Copper pipe with lead solder • Galvanized iron 16
ATTACHMENT 1 - ITEM 6.2 Control Jars with Epoxy Only Control 1 Control 2 Control 3 Control 4 (GW-7.5) (GW-7.5-OP) (SW-7.2-OP) (SW-7.8-OP) Control analyte measurements taken after 2 days stagnation 17
ATTACHMENT 1 - ITEM 6.2 Asbestos Calcium Cement Alternating Sources 120 Week 0_Control SW SW SW SW SW SW Week 0 GW GW GW 100 Week 4_Control Week 4 Calcium (mg/L) Week5_Control 80 Week 5 Week6_Control 60 Week 6 Week8_Control 40 Week 8 Week9_Control 20 Week 9 Week10_Control Week 10 0 Week 12_Control Week 12 Week 13_Control Week 13 Testing shows no concern for calcium scale dissociation 18
ATTACHMENT 1 - ITEM 6.2 Asbestos Phosphorous Cement Alternating Sources Week 0_Control 300 Week 0 SW SW SW SW SW SW GW GW GW Week 4_Control 250 Week 4 Phosphorus (µg/L) Week5_Control 200 Week 5 Week6_Control 150 Week 6 Week8_Control 100 Week8 Week9_Control Week 9 50 Week10_Control Week 10 0 Week 12_Control Week 12 Week 13_Control Week 13 Detection Limit = 10 µg/L Minimal to no uptake of phosphorous 19
ATTACHMENT 1 - ITEM 6.2 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) 20
ATTACHMENT 1 - ITEM 6.2 Copper Pipe/ Copper Lead Solder Alternating Sources 2,500 Conditioning SW SW SW SW SW SW GW GW GW Week 0 2,000 Week 4 Copper (µg/L) Week 5 1,500 Week 6 1,000 Week 8 Week 9 500 Week 10 Week 12 0 Week 13 Minimal changes in Cu except for a spike in C6 21
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