Managing ph in Large Diameter Cement Mortar Lined Pipelines with Infrequent Use

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1 Managing ph in Large Diameter Cement Mortar Lined Pipelines with Infrequent Use May 1, 2014 Michael Hartlaub, P.E. Ali Sheikholeslami, P.E.

2 Good Intentions

3 Unintended Consequences

4 Outline Background project Cement mortar lining and ph issue Treatment alternatives Design & procurement of treatment system Construction and start-up

5 EBMUD Service Area Serves 1.3 M people in SF East Bay Area 7 reservoirs 5 WTPs 136 PPs 67 distribution reservoirs 4,000 miles of pipe 5

6 Folsom South Canal Connection Pipeline (FSCC) Water Discharge to Local Creeks FSCC Pipeline

7 FSCC Pipeline Dry years supply Average 2-3 yrs/10 yrs 100 mgd from Folsom South Canal to EBMUD s Mokelumne Aqueducts 19 miles of 66-inch pipe ½ mortar cement lining, ASTM C 150 Type II cement, factory applied Completed in 2011

8 NPDES Discharge Limits Orinda Spillway San Pablo Creek NPDES Limits ph

9 Sacramento River Water Quality at Freeport Intake Water Quality Parameter Ave. Value Unit Turbidity 14 NTU TOC 2.2 mg/l TDS 92 mg/l ph 7.5 ph Units Alkalinity 58 mg/l as CaCO 3 Calcium 12 mg/l

10 After Start-up Test Elevated ph Water Drained & Treated with Acid Locations to pump and treat 22 mg of water discharged to local creeks Cost of draining & treating approx. $250,000 WQ monitoring & reporting to RWQCB 6 to 8 weeks ph rebounded after 24 hours

11 Why MCL Causes ph problem? MCL = Sand + Portland Cement + Water Dry cement is hydrated forms calcium hydroxide or lime, Ca(OH) 2 Ca(OH) 2 is leached out of CML under low alkalinity gives Ca OH - Factors: time, cement type, method of application, buffer capacity, age, diameter

12 ph Increase in FSCC Pipeline Above ph 8.5 NPDES Violation

13 Alkalinity Increase in FSCC Pipeline

14 Alternative for ph Control Advantages Carbon Dioxide Good ph Control Safe to Handle Strong Acid (HCl, H 2 SO 4 ) Lower Capital Cost Fast Reacting Disadvantage Difficult Design New Infrastructure Higher Capital Cost No Experience Feed Location Important (pressure, contact time) Capital Cost $2M $400K Difficult to Control Overfeed likely Safety & Handling Issues New Infrastructure

15 Engineered Inline System Needed System Goals Automatic control (direct flow and ph signals) Remote monitoring and control Secure locations Onsite power Good dissolution of CO2 Low and High flow control valves Sites Selected Bixler Facility, near Brentwood, for primary control (Aqueducts at 200 psi) Walnut Creek Raw Water Pumping Plant for Backup Control (Aqueducts at 120 psi)

16 CO 2 Feed Locations WCPP Bixler Facility FSCC Pipeline

17 CO2 Systems Gas Systems Added at Bixler and Walnut Creek Pumping Plant Briones Res. Orinda WTP Lafayette WTP Walnut Creek WTP Walnut Creek PP (Backup) Bixler Facility CO 2 CO 2 Pardee Res. AQ1 AQ2 AQ3 Sobrante WTP To San Pablo Creek Discharge Limit ph 8.5 To USL Reservoir Discharge Limit ph 8.5 USL WTP FSCC 100 MGD

18 Design Criteria Design Criteria Design Range Feed Control System Flow Rate Range CO 2 Dosage Rate Feed Rate (Both Aqueducts) Target ph 7.5 CO 2 System Storage Required Storage MGD mg/l 17 2,800 lbs/hr 14 Tons 300psi / 0 F

19 ph Control System ph Monitor Carbon Dioxide Liquid Storage Tank Vaporizer Gas Feed Controller Control Feedback ph Monitor Heater 500 High ph Lower ph

20 Project Schedule System Request - 3/12 Purchase Spec - 7/12 Vendor Selection 8/12 TOMCO2 Co. Factory Test 12/12 1 st Unit Delivered 2/13 1 st Unit Startup 3/13 2 nd Unit Startup 3/14

21 CO2 Storage & Feed System Carbon Dioxide Storage System 14 ton liquid CO 2 storage tank 2 Electric vaporizer Electric heater Refrigeration system Feed Control System CO2 Gas Feed & ph Control System CO 2 gas feed control valves Low-flow valve, lb/hr High-flow valve, lb/hr Pressure control Mass flow indicators/transmittor PLC control

22 Site Preparation at Bixler

23 CO2 Gas Lines for Aqueducts Stainless steel welded CO2 pipelines Used existing chemical trenches and manholes

24 Diffusers Installed inside Aqueducts Installing the Diffuser Manifold Finished Diffuser Special fine bubble Diffusers work at 200psi

25 Feed Controls System

26 Finished Product at Bixler Secure Feed Control Building Electrical and RTU Panels

27 Finished Product at Bixler Bulk Gas Unloading Pad

28 Back up System at Walnut Creek Raw Water Pumping Plant

29 Back up System WCPP

30 Startup Tests Results Decreased ph from 8.5 to 7.5 using lowflow valve ph controlled to 0.1 ph units Diffusers quickly dissolved CO 2 gas CO 2 feed was controlled automatically Integrated into SCADA and Op/Net system CO 2 system ready for operation Plan to start FSCC April 2, 2014 High ph slug will arrive at Bixler on April 4 at 9 a.m.,15 mgd per each aqueduct

31 Special Thanks to Team Engineering Michael Hartlaub, Angela Curtis Aqueduct Roberto Cortez, Steve Dooley, Tim Meyers Maintenance Jafar Mohsen, Martin Castello SCADA and Op/Net Engineering Purchasing & TOMCO2 Equipment Co.

32 QUESTIONS??