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Dual Use of Ocean Outfall Pipeline Tertiary Effluent Delivery to Two Golf Courses Using Existing Secondary Effluent Pipeline Presented by Dana K. Ripley.

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Presentation on theme: "Dual Use of Ocean Outfall Pipeline Tertiary Effluent Delivery to Two Golf Courses Using Existing Secondary Effluent Pipeline Presented by Dana K. Ripley."— Presentation transcript:

1 Dual Use of Ocean Outfall Pipeline Tertiary Effluent Delivery to Two Golf Courses Using Existing Secondary Effluent Pipeline Presented by Dana K. Ripley and Bahman Sheikh at the 28 th Annual WateReuse Symposium Denver, CO September 16, 2013

2 Overview l Santa Cruz County Water Supply Background l Scotts Valley Water Recycling System l Scotts Valley 8-mile Ocean Outfall l Pasatiempo Golf Course l Santa Cruz potable water customer since 1929 l “Dual Use” Concept – Secondary and Tertiary Effluent in Single Pipe l Consultation with California Department of Public Health l Pipeline Disinfection Process l CDPH Engineering Report, Review and Final Approval l Current Project Status

3 Santa Cruz, CA Water Supply Issues l Water Supply Shortage during Drought Conditions: the City could experience a 45% shortfall in water supply during a drought event similar to the one experienced in 1976-77. l Endangered Species Preservation and Habitat Conservation: Since Santa Cruz is predominantly reliant on surface water, future water availability is subject to reduction due to regulatory requirements in place to protect fish. l Water Rights: The City has two water rights applications pending that could potentially affect reservoir operations. Denial of the water rights petitions would result in reduction of surface water supply. l Groundwater Overdraft: An increased demand for ground- water throughout the basin has created overdraft conditions. Source: SCWD 2, December 2010

4 Drought Curtailment Allocations Source: City of Santa Cruz 2010 Urban Water Management Plan

5 Santa Cruz County Water Suppliers Source: Kennedy/Jenks Consultants, 2009

6 Scotts Valley Ocean Outfall Base image and profile: Google Earth, May 2012 imagery Scotts Valley WWTP Pasatiempo Golf Course Santa Cruz/ Scotts Valley joint outfall Santa Cruz WWTP North

7 Dual Use Concept l Scotts Valley WWTP needs to discharge >1 mgd in winter. l Outfall rated at 4 mgd, but tertiary filter and UV disinfection system rated at 1 mgd. l Dry weather flow in summer less than 0.8 mgd. l Outfall pipe will convey secondary effluent in winter for ocean discharge, and tertiary effluent in summer months for reuse. l Disinfection protocol will be required each spring to convert from secondary to tertiary. l Initiated by Pasatiempo Golf Club, but others may include Valley Garden Golf Course and Santa Cruz Memorial Cemetery. l Dual use of pipeline eliminates need for either on-site tertiary treatment or single purpose dedicated tertiary pipeline. l Cost savings in the range of $5 to $10 million.

8 2012 SV WWTP Recycle and Discharge

9 Pasatiempo Golf Club Water Conservation

10 Pasatiempo Golf Club Turf Reduction March 2007 May 2012

11 Underground Effluent Storage Source: DN Tanks, Inc. Similar 1.1 MG Circumferentially Pre- stressed Concrete Tank Fully Buried Under Construction

12 Effluent Storage Fully Buried Source: DN Tanks, Inc. Similar 1.1 MG Pre-stressed Concrete Tank Fully Buried located at Lone Tree Golf Course in Antioch, CA

13 Why Go to Dual Use? l Options: n New Tertiary Plant--$4-7 Million n New 3-Mile Pipeline--$5 Million n Use Existing Outfall--$0.3 Million l Stubbed-Out Turnouts Available l Turnouts Plumbed to Private Property in Two locations in 1980 l Designed for Plug ‘n Play Connections to On-Site Storage Tank l No Conflict with Ongoing Ops

14 Annual Cycle of Dual Use: Discharge and Reuse JanFebMarAprMayJunJulAugSepOctNovDec Disinfected Secondary Effluent to Ocean Discharge Disinfected Tertiary Recycled Water Conveyance to Pasatiempo Golf Course Disinfected Secondary Effluent to Ocean Discharge Transition from 2 nd to 3 ry Transition from 3 ry to 2 nd

15 Consultation with CDPH l Title 22 n Water Quality Criteria at End-of-Treatment Train l Criteria Not Applicable to Transmission Line l However, In the Spirit of Title-22 n Consultation with CDPH n Prepared Engineering Report u Flush or Disinfect the Pipeline u Monitor at End-of-Pipe u Transition Period—Restricted-Access Irrigation, at Night

16 Transition from Discharge to Reuse l March-April Timeframe l Seasonal Flushing n If Proven Sufficient n Based on Total Coliform at End of Pipe l Seasonal Disinfection n If Necessary

17 Profile of 12” Outfall to Pasatiempo

18 Flushing l Fill the Pipe, Remove All Air l Slowly Flush Two Pipe Volumes l Store Flush Water in Storage Tank l Sample for Total Coliform l Decide if Disinfection Is Necessary l Irrigate with Sored Water n Restricted Access--Temporarily

19 Disinfection Process (If Necessary) l Fill Pipe, Remove All Air l Disinfect with Chlorine or Paracetic Acid (PAA) l 2 Hours Disinfectant Contact l Flush, Keep Flush Water in Storage l Test for Total Coliform l Repeat if Necessary

20 Consultation with CDPH l Engineering Report l Three Drafts, Each Responding to CDPH Comments l Acceptance Letter from CDPH to RWQCB on 10/11/12 n Signage Plan Required prior to Delivery of Recycled Water


22 Why Paracetic Acid? l PAA Advantages Over Chlorine n Easy to Work with n Effective at Low Concentrations n Effective / Stable in Biofilm n Industry Standard for Disinfection of Metal Surfaces n No Liquid Hypochlorite Salts (eg. Sodium) n De-Chlorination Unnecessary l PAA Approved in November 10, 2012 by CDPH Acceptance Letter

23 Future Plans l Engineering Study in Progress n On-site WWTP Replumbing for Tertiary Effluent to Outfall Pump Station n Pressure Reduction Valve in Outfall Pipe n Full Pipe in Downhill Segment of Outfall Pipe for Disinfection l Agreements Among Stakeholders Including Scotts Valley Water District, City of Scotts Valley, and Pasatiempo l Potential Additional Users of Recycled Water Along Outfall Pipe l First Water Recycling Project for Santa Cruz l Likely More Recycling to Follow as Alternative to Desalinization


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