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

Different uses of recycled w ater require different levels of treatment Irrigation Irrigation/Industrial Seawater Barrier 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; or full treatment at irrigation sites

1.a Recycled Water for Irrigation (Centralized) – Concepts and Potential Supplemental Supply Conceptual Description of Alternative: Supply AFY • Secondary effluent from Santa Cruz WWTP Average Annual Recycled 510 • Filtration Plant at WWTP or near Schwan Lagoon Water • Rail Trail Purple Pipeline Potential Supplemental 510 • Pumping and Distribution to ~20 irrigation users Supply or Groundwater Replenishment • Additional District potable supply or GW replenishment by providing recycled water to reduce private well pumping

1.a Recycled Water for Irrigation (Centralized) – Advantages, Challenges and Conceptual Costs Advantages: Alternative 1.a Costs Unit • Sustainable and reliable irrigation supply Treatment $16 Mil Conveyance $42 Mil • Park and school field use maintained during Wells $0 Mil droughts Soft Costs $10 Mil • Reduces groundwater pumping Total Capital Costs $68 Mil Challenges : Annual O&M $0.9 Mil/yr • Complicated on-site retrofits for some users Annualized Unit Costs $8,600 $/AF • Requires negotiation with private wells to reduce or stop pumping; complicated monitoring and enforcement.

1.b Recycled Water for Irrigation (Satellite) - Concepts and Potential Supplemental Supply Conceptual Description of Alternative : Supply AFY • Raw wastewater from sewer Average Annual Recycled 315 • 2 Biological and filtration treatment SRPs at Seascape GC and Water Polo Grounds Potential Supplemental 315 • Pumping, Storage and Distribution to ~4 users Supply or Groundwater • Additional District potable supply or GW replenishment by Replenishment providing recycled water to reduce private well pumping

1.b Recycled Water for Irrigation (Satellite) - Advantages, Challenges and Conceptual Costs Advantages: • Sustainable and reliable irrigation supply Alternative 1.b Costs Unit • Facility use maintained during droughts Treatment $16 Mil • Reduces groundwater pumping Conveyance $6 Mil • Minimizes distribution pipelines Wells $0 Mil Soft Costs $8 Mil Total Capital Costs $30 Mil Challenges : • Complicated biological treatment of raw wastewater Annual O&M $0.5 Mil/yr • May only benefit part of groundwater basin Annualized Unit Costs $6,500 $/AF • Requires negotiation with private wells to reduce or stop pumping; complicated monitoring and enforcement.

Recycled Water can be injected along the coast to create a Seaw ater Intrusion Barrier Seaw ater Intrusion Land surf ace We l l W a t e r t a ble Ocean Gr oundw a t er basin Bedr ock

Recycled Water can be injected along the coast to create a Seaw ater Intrusion Barrier Seaw ater Intrusion Land surf ace We l l W a t e r t a ble Ocean Gr oundw a t er basin Bedr ock Seaw ater Intrusion Barrier Land surf ace We l l Injection we l l W a t e r t a ble Ocean Gr oundw a t er basin Bedr ock

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

2. Seaw ater Intrusion Barrier + Irrigation Water - Concepts and Potential Supplemental Supply Description: Supply AFY • Secondary effluent from Santa Cruz WWTP • Advanced Treatment near Schwan Lagoon Average Annual Recycled 4,000 • Rail Trail Purple Pipeline Water • Assumed 10 Seawater injection wells Potential Supplemental • Additional District potable supply or GW replenishment Supply or Groundwater 1,030 by providing recycled water to reduce private well Replenishment pumping • Assumed 15% of barrier water blends with groundwater supply Seawater Injection Well

2. Seaw ater Intrusion Barrier + Irrigation Water – Advantages, Challenges and Conceptual Costs Advantages: • Park and school field use maintained during Alternative 2 Costs Unit droughts Treatment $54 Mil • Protection from Seawater Intrusion Conveyance $59 Mil • Potential backflow effect (push groundwater inland) Wells $26 Mil • Use purple pipeline for both barrier injection and Soft Costs $15 Mil irrigation Total Capital Costs $154 Mil Challenges : Annual O&M $2.2 Mil/yr • High quality water flows out to ocean Annualized Unit Costs $9,700 $/AF • Hydro-geologic modeling to confirm concept, injection locations and volumes • Requires negotiation with private wells to reduce or stop pumping; complicated monitoring and enforcement Seawater Injection Well

Recycled Water for Groundw ater Replenishment • 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 New regulations permit 2 to 6-month separation distance from neighboring wells.

3. Groundw ater Replenishment + Irrigation Water - Concepts and Potential Supplemental Supply Description: • Secondary effluent from Santa Cruz WWTP Supply AFY • Advanced Treatment near Schwan Lagoon Average Annual Recycled Water 2,800 • Rail Trail Purple Pipeline Potential Supplemental Supply or 2,230 • Assumed 4 replenishment injection wells Groundwater Replenishment • 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 Groundwater Injection Well

3. Groundw ater Replenishment + Irrigation Water – Advantages, Challenges and Conceptual Costs Advantages: • Meets supplemental water supply objective Alternative 3 Costs Unit • More rapid groundwater replenishment Treatment $46 Mil • Park and school field use maintained during Conveyance $54 Mil droughts Wells $19 Mil • Use purple pipeline for both injection and irrigation Soft Costs $15 Mil Total Capital Costs $134 Mil Challenges: Annual O&M $2.0 Mil/yr • Regulatory and public perception challenges • Hydro-geologic modeling to confirm concept, Annualized Unit Costs $4,000 $/AF recharge locations and volumes • Proximity to existing public/private wells may significantly limit injection well locations Groundwater Injection Well

4. Groundw ater Replenishment + Seaw ater Barrier + Irrigation Water - Concepts and Potential Supplemental Supply Description: Supply AFY • Secondary effluent from Santa Cruz WWTP Average Annual Recycled • Advanced Treatment near Schwan Lagoon 6,200 Water • Same Rail Trail Purple Pipeline for all uses Potential Supplemental Supply • Assumed 10 seawater barrier injection wells 2,750 or Groundwater Replenishment • Assumed 4 replenishment injection wells • Same assumptions as previous elements Seawater Injection Well Groundwater Injection Well