Opportunities for Recycled Water as a Supplemental Supply Todd - - PowerPoint PPT Presentation

Opportunities for Recycled Water as a Supplemental Supply

Todd Reynolds, PE, BCEE

Presentation Outline

Previous recycled water studies and benefits of recycled water Overview of treatment required for different uses of recycled water Potential Recycled Water Opportunities for SqCWD

• Conceptual Project Components and Water Volumes
• Advantages and Challenges
• Conceptual Level Costs

Questions

District IRP evaluated recycled w ater

• pportunities

SqCWD Previous Recycled Water Studies

• Integrated Resources Plan (ESA,

2006)

• Water Recycling Facilities

Planning Study (Black & Veatch, 2009)

• Identified opportunities for

Satellite Reclamation Plants (SRP)

Overall Benefits and Challenges of Recycled Water

• Reliable, drought-resistant source of water
• A “local” resource – not imported
• Lower energy use than seawater
• State officials and regulators are starting to support the

expanded use of recycled water

• Public’s perception and education
• Regulatory hurdles for potable reuse type projects

Benefits Challenges

Different uses of recycled w ater require different levels of treatment

Seawater Barrier Irrigation Irrigation/Industrial

Secondary Effluent

An additional environmental or engineered barrier is required for potable reuse

Advanced Treatment

• Filtration
• RO
• Advanced Oxidation

Blending with traditional water source Environmental buffer of 2 to 6 months of groundwater detention Environmental buffer of <25% blend in Reservoir

Potential Recycled Water Alternatives for SqCWD

1. Irrigation of Parks, Golf Courses, Etc.

• Centralized Treatment and Distribution
• Satellite Treatment and Use

2. Seawater Intrusion Barrier 3. Groundwater Replenishment 4. Combination of the Above 5. Other regional recycled water opportunities

Recycled Water for Non-Potable Irrigation

• Filtration and disinfection

treatment Required

• Water for large urban

irrigation such as parks, sports fields, etc.

• Centralized filtration

treatment and distribution;

• r full treatment at

irrigation sites

1.a Recycled Water for Irrigation (Centralized) – Concepts and Potential Supplemental Supply

Conceptual Description of Alternative:

• Secondary effluent from Santa Cruz WWTP
• Filtration Plant at WWTP or near Schwan Lagoon
• Rail Trail Purple Pipeline
• Pumping and Distribution to ~20 irrigation users
• Additional District potable supply or GW replenishment by

providing recycled water to reduce private well pumping Supply AFY

Average Annual Recycled Water 510 Potential Supplemental Supply or Groundwater Replenishment 510

1.a Recycled Water for Irrigation (Centralized) – Advantages, Challenges and Conceptual Costs

Advantages:

• Sustainable and reliable irrigation supply
• Park and school field use maintained during

droughts

• Reduces groundwater pumping

Challenges :

• Complicated on-site retrofits for some users
• Requires negotiation with private wells to reduce or

stop pumping; complicated monitoring and enforcement. Alternative 1.a Costs Unit Treatment $16 Mil Conveyance $42 Mil Wells $0 Mil Soft Costs $10 Mil Total Capital Costs $68 Mil Annual O&M $0.9 Mil/yr Annualized Unit Costs $8,600 $/AF

1.b Recycled Water for Irrigation (Satellite) - Concepts and Potential Supplemental Supply

Conceptual Description of Alternative :

• Raw wastewater from sewer
• 2 Biological and filtration treatment SRPs at Seascape GC and

Polo Grounds

• Pumping, Storage and Distribution to ~4 users
• Additional District potable supply or GW replenishment by

providing recycled water to reduce private well pumping

Supply AFY Average Annual Recycled Water 315 Potential Supplemental Supply or Groundwater Replenishment 315

1.b Recycled Water for Irrigation (Satellite) - Advantages, Challenges and Conceptual Costs

Advantages:

• Sustainable and reliable irrigation supply
• Facility use maintained during droughts
• Reduces groundwater pumping
• Minimizes distribution pipelines

Challenges :

• Complicated biological treatment of raw wastewater
• May only benefit part of groundwater basin
• Requires negotiation with private wells to reduce or stop

pumping; complicated monitoring and enforcement. Alternative 1.b Costs Unit Treatment $16 Mil Conveyance $6 Mil Wells $0 Mil Soft Costs $8 Mil Total Capital Costs $30 Mil Annual O&M $0.5 Mil/yr Annualized Unit Costs $6,500 $/AF

Recycled Water can be injected along the coast to create a Seaw ater Intrusion Barrier

W a t e r t a ble Gr

• undw

a t er basin Land surf ace Bedr

• ck

Ocean We l l

Seaw ater Intrusion

Recycled Water can be injected along the coast to create a Seaw ater Intrusion Barrier

W a t e r t a ble Gr

• undw

a t er basin Land surf ace Bedr

• ck

Ocean We l l W a t e r t a ble Gr

• undw

a t er basin Land surf ace Bedr

• ck

Ocean Injection we l l We l l

Seaw ater Intrusion Seaw ater Intrusion Barrier

Recycled Water for Seaw ater Intrusion Barrier

• Advanced Treatment

Required

• Water creates barrier

and primarily flows out to ocean

• Injection wells located

near the coast where intrusion is starting

Seawater Injection Well

• 2. Seaw ater Intrusion Barrier + Irrigation Water -

Concepts and Potential Supplemental Supply

Description:

• Secondary effluent from Santa Cruz WWTP
• Advanced Treatment near Schwan Lagoon
• Rail Trail Purple Pipeline
• Assumed 10 Seawater injection wells
• Additional District potable supply or GW replenishment

by providing recycled water to reduce private well pumping

• Assumed 15% of barrier water blends with groundwater

supply

Supply AFY Average Annual Recycled Water 4,000 Potential Supplemental Supply or Groundwater Replenishment 1,030

Seawater Injection Well

• 2. Seaw ater Intrusion Barrier + Irrigation Water –

Advantages, Challenges and Conceptual Costs

Advantages:

• Park and school field use maintained during

droughts

• Protection from Seawater Intrusion
• Potential backflow effect (push groundwater inland)
• Use purple pipeline for both barrier injection and

irrigation Challenges :

• High quality water flows out to ocean
• Hydro-geologic modeling to confirm concept, injection

locations and volumes

• Requires negotiation with private wells to reduce or

stop pumping; complicated monitoring and enforcement Alternative 2 Costs Unit Treatment $54 Mil Conveyance $59 Mil Wells $26 Mil Soft Costs $15 Mil Total Capital Costs $154 Mil Annual O&M $2.2 Mil/yr Annualized Unit Costs $9,700 $/AF

Recycled Water for Groundw ater Replenishment

New regulations permit 2 to 6-month separation distance from neighboring wells.

• Advanced treatment,

blending and environmental barrier required

• Highly treated water would

be injected into GW Basin away from the coast

• Supplemental supply water

is then withdrawn from current wells

Groundwater Injection Well

• 3. Groundw ater Replenishment + Irrigation Water -

Concepts and Potential Supplemental Supply

Description:

• Secondary effluent from Santa Cruz WWTP
• Advanced Treatment near Schwan Lagoon
• Rail Trail Purple Pipeline
• Assumed 4 replenishment injection wells
• Additional District potable supply or GW

replenishment by providing recycled water to reduce private well pumping

• Assumed 25% of injected water flows out to ocean

Supply AFY Average Annual Recycled Water 2,800 Potential Supplemental Supply or Groundwater Replenishment 2,230

Groundwater Injection Well

• 3. Groundw ater Replenishment + Irrigation Water –

Advantages, Challenges and Conceptual Costs

Advantages:

• Meets supplemental water supply objective
• More rapid groundwater replenishment
• Park and school field use maintained during

droughts

• Use purple pipeline for both injection and irrigation

Challenges:

• Regulatory and public perception challenges
• Hydro-geologic modeling to confirm concept,

recharge locations and volumes

• Proximity to existing public/private wells may

significantly limit injection well locations Alternative 3 Costs Unit Treatment $46 Mil Conveyance $54 Mil Wells $19 Mil Soft Costs $15 Mil Total Capital Costs $134 Mil Annual O&M $2.0 Mil/yr Annualized Unit Costs $4,000 $/AF

Seawater Injection Well Groundwater Injection Well

• 4. Groundw ater Replenishment + Seaw ater Barrier + Irrigation

Water - Concepts and Potential Supplemental Supply

Description:

• Secondary effluent from Santa Cruz WWTP
• Advanced Treatment near Schwan Lagoon
• Same Rail Trail Purple Pipeline for all uses
• Assumed 10 seawater barrier injection wells
• Assumed 4 replenishment injection wells
• Same assumptions as previous elements

Supply AFY Average Annual Recycled Water 6,200 Potential Supplemental Supply

• r Groundwater Replenishment

2,750

Seawater Injection Well Groundwater Injection Well

• 4. Groundw ater Replenishment + Seaw ater Barrier + Irrigation

Water - Advantages, Challenges and Conceptual Costs

Advantages:

• Meets supplemental water supply objective
• Protection from Seawater Intrusion
• More rapid groundwater replenishment
• Park and school field use maintained during

droughts

• Use purple pipeline for both injection and irrigation

Challenges :

• Regulatory and public perception challenges
• Hydro-geologic modeling to confirm concept,

injection locations and volumes

• Proximity to existing public/private wells may

significantly limit injection well locations Alternative 4 Costs Unit Treatment $70 Mil Conveyance $61 Mil Wells $44 Mil Soft Costs $15 Mil Total Capital Costs $190 Mil Annual O&M $3.1 Mil/yr Annualized Unit Costs $4,600 $/AF

Summary of Recycled Water Supplemental Supply Alternatives – Supply Volumes and Conceptual Costs

Alt Description Potential Supplemental Supply (AFY) Conceptual Capital Cost (mil $) Project Annualized Unit Cost ($/AF) 1a Centralized Recycled Water for Irrigation in SqCWD 510 $68 $8,600 1b Decentralized Recycled Water for Irrigation in SqCWD 315 $30 $6,500 2 Recycled Water for Seawater Intrusion Barrier and Irrigation in SqCWD 1,030 $154 $9,700 3 Recycled Water for GW Replenishment and Irrigation in SqCWD 2,230 $134 $4,000 4 Recycled Water for GW Replenishment, Seawater Intrusion Barrier and Irrigation in SqCWD 2,750 $190 $4,600

Other Regional Options: Recycled w ater from Scotts Valley or Watsonville

• Bring irrigation quality recycled water from other nearby

sources

• Recycled water is already used in local community and there

may not be reliable excess water

• Additional advanced treatment would still be required for

injection barrier or replenishment

• Recycled water may be better used for local replenishment

projects in Scotts Valley and Watsonville

Opportunity Challenges

Other Regional Options: Recycled w ater could be added to Loch Lomond to augment w ater supply

Advantages:

• Reliable supplemental supply
• Could provide both the District and the City with a

supplemental supply

• Could provide environmental, stream flow benefits
• Could share project costs with the City
• Regulation changes could permit potable reuse

concepts in the near future Challenges:

• Not currently permitted
• Regulatory and public perception challenges
• Loch Lomond would be >50% recycled water
• Requires significant engagement with CDPH and

pilot testing

Questions and Discussion

• Reliable, drought-resistant source
• f water
• A “local” resource
• Lower energy use than seawater
• State officials and regulators are

starting to support the expanded use of recycled water

• Public’s Perception and Education
• Regulatory hurdles for potable reuse type

projects

Benefits Challenges