Dual Use of Ocean Outfall Pipeline

Tertiary Effluent Delivery to Two Golf CoursesUsing Existing Secondary Effluent Pipeline

Presented by

Dana K. Ripley and Bahman Sheikh

at the28th Annual WateReuse Symposium

Denver, CO

September 16, 2013

Overview

Santa Cruz County Water Supply Background Scotts Valley Water Recycling System Scotts Valley 8-mile Ocean Outfall Pasatiempo Golf Course Santa Cruz potable water customer since 1929 “Dual Use” Concept – Secondary and Tertiary

Effluent in Single Pipe Consultation with California

Department of Public Health Pipeline Disinfection Process CDPH Engineering Report,

Review and Final Approval Current Project Status

Santa Cruz, CA Water Supply Issues

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.

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.

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.

Groundwater Overdraft: An increased demand for ground-water throughout the basin has created overdraft conditions.

Source: SCWD2, December 2010

Drought Curtailment AllocationsSo

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ity o

f San

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2010

Urb

an W

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Man

agem

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Santa Cruz County Water Suppliers

Source: Kennedy/Jenks Consultants, 2009

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

Dual Use Concept

Scotts Valley WWTP needs to discharge >1 mgd in winter. Outfall rated at 4 mgd, but tertiary filter and UV disinfection

system rated at 1 mgd. Dry weather flow in summer less than 0.8 mgd. Outfall pipe will convey secondary effluent in winter for ocean

discharge, and tertiary effluent in summer months for reuse. Disinfection protocol will be required each spring to convert

from secondary to tertiary. Initiated by Pasatiempo Golf Club, but others may include Valley

Garden Golf Course and Santa Cruz Memorial Cemetery. Dual use of pipeline eliminates need for either on-site tertiary

treatment or single purpose dedicated tertiary pipeline. Cost savings in the range of $5 to $10 million.

2012 SV WWTP Recycle and Discharge

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec0

5

10

15

20

25

30

35

2012 Scotts Valley WWTP Total Flow 2012 SVWD Tertiary Recycle Tertiary Recycle - PT Interdiction

2012 Secondary Ocean Discharge Ocean Discharge - PT Interdiction

Mill

ion

Gal

lons

per

Mon

th

Pasatiempo Golf Club Water Conservation

Pasatiempo Golf Club Turf Reduction

March 2007 May 2012

Underground Effluent Storage

Source: DN Tanks, Inc.

Similar 1.1 MG Circumferentially Pre-stressed Concrete Tank Fully Buried Under Construction

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

Why Go to Dual Use?

Options: New Tertiary Plant--$4-7 Million New 3-Mile Pipeline--$5 Million Use Existing Outfall--$0.3 Million

Stubbed-Out Turnouts Available Turnouts Plumbed to Private Property in

Two locations in 1980 Designed for Plug ‘n Play Connections

to On-Site Storage Tank No Conflict with Ongoing Ops

Annual Cycle of Dual Use: Discharge and Reuse

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Disinfected Secondary Effluent

to Ocean

Discharge

Disinfected Tertiary Recycled Water Conveyance

to Pasatiempo Golf Course

Disinfected

Secondary Effluent

to Ocean

DischargeTransition from 2nd to 3ry

Transition from 3ry to 2nd

Consultation with CDPH

Title 22 Water Quality Criteria at End-of-Treatment Train

Criteria Not Applicable to Transmission Line However, In the Spirit of Title-22

Consultation with CDPH Prepared Engineering Report

Flush or Disinfect the Pipeline Monitor at End-of-Pipe Transition Period—Restricted-Access Irrigation, at

Night

Transition from Discharge to Reuse

March-April Timeframe Seasonal Flushing

If Proven Sufficient Based on Total Coliform at End of Pipe

Seasonal Disinfection If Necessary

Profile of 12” Outfall to Pasatiempo

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16,00

0 400

425

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675

Distance from Pump Station (Feet)

Elev

atio

n M

SL (F

eet)

Pum

p St

atio

n at

Sco

tts V

alle

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WTP

Whi

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Flushing

Fill the Pipe, Remove All Air Slowly Flush Two Pipe Volumes Store Flush Water in Storage Tank Sample for Total Coliform Decide if Disinfection Is Necessary Irrigate with Sored Water

Restricted Access--Temporarily

Disinfection Process (If Necessary)

Fill Pipe, Remove All Air Disinfect with Chlorine

or Paracetic Acid (PAA) 2 Hours Disinfectant Contact Flush, Keep Flush Water in Storage Test for Total Coliform Repeat if Necessary

Consultation with CDPH

Engineering Report Three Drafts, Each Responding to CDPH

Comments Acceptance Letter from CDPH to RWQCB on

10/11/12 Signage Plan Required prior to Delivery of

Recycled Water

Why Paracetic Acid?

PAA Advantages Over Chlorine Easy to Work with Effective at Low Concentrations Effective / Stable in Biofilm Industry Standard for Disinfection of Metal

Surfaces No Liquid Hypochlorite Salts (eg. Sodium) De-Chlorination Unnecessary

PAA Approved in November 10, 2012 by CDPH Acceptance Letter

Future Plans

Engineering Study in Progress On-site WWTP Replumbing for Tertiary Effluent to Outfall

Pump Station Pressure Reduction Valve in Outfall Pipe Full Pipe in Downhill Segment of Outfall Pipe for

Disinfection Agreements Among Stakeholders Including Scotts Valley Water

District, City of Scotts Valley, and Pasatiempo Potential Additional Users of Recycled Water Along Outfall Pipe First Water Recycling Project for Santa Cruz Likely More Recycling to Follow as Alternative to Desalinization

Thank You for Your Attention