Advancements in ASR Well Design and Operations - City of Phoenix Case Study
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The document discusses advancements in aquifer storage and recovery (ASR) well design and operations using a case study from the City of Phoenix. It summarizes that the city uses ASR wells to store treated surface water in aquifers during off-peak months and recover the water during peak months. It describes new methods developed including using glass beads instead of sand for the filter pack, which increased recharge and recovery efficiencies. It also details a reverse siphon recharge method that reduces clogging and air entrainment compared to conventional down-hole valves, lowering operating and maintenance costs. The case study demonstrates ASR can be a cost-effective way to increase water supply capacity and flexibility.
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Advancements in ASR Well Design and Operations - City of Phoenix Case Study
- 2. 2013 - 1.3 Million Customers 97% Surface Water - Potable 3% Groundwater Water - Potable City of Phoenix Service Area Service Area- 525 square miles
- 3. Phoenix Wells: Groundwater Levels 1000 1050 1100 1150 1200 1250 1300 initial static water level Elevation(feet) Well 292- 1.5 ft/yr Well 281- 4 ft/yr Well 280- 4 ft/yr Well 276- 3 ft/yr Well 299- 3 ft/yr Well 261- 3.6 ft/yr Well 291- 5 ft/yr Well 293- 5.6 ft/yr Well 294- 2.7 ft/yr Well 288- 5.5 ft/yr Time (years) 1978-2012 32 years of groundwater pumping- 125 feet of dewatering the aquifer Depth to water 430 to 855 feet below land surface
- 4. Injection/Storage Vadose Zone Recovery from Same Well System Aquifer Storage & Recovery – Dual Purpose Well Injection/ Storage During Off-Peak Months Recover water during Peak Months Aquifer
- 5. ! ! ! Zone 7 Zone 5 Pinnacle Peak Road Jomax Road Union Hills Water Treatment Plant Phoenix Production Well ASR Well #299 N0.5 1 Mile 0 Existing 54-Inch Transmission Main To Potable Water System 6A-Well #299 Initially Store - 1,500 acre – Feet/Year Recover - 300 acre -Feet/Year Source Water: Treated CAP Water Annual Storage – 1,200 acre– Feet/Year Zone 6 City of Phoenix Goals: • Cost effective • Recharge at a high utilization rate -75- 80% • Reduce operations and maintenance costs (include Arsenic treatment systems and energy costs) • Achieve about 1,200-1,400 acre- feet per year per well • Total recharge capacity build out 14,000-16,000 acre- feet per year from 10-12 wells • Increase well-field capacity by 18,000 to 20,000 acre-feet per year
- 6. Line-shaft Turbine Pump -650’- Static Water Level -838’- Top of Screen Filter Pack Implement injection and recovery cycles Increase connectivity between filter pack and borehole interface •Air Binding •Grain on Grain Contact: Abrasion • Finer Grained Sediments and Particulates Filling Pore Spaces • Cementation • Dissolution • Biofilm Development Locations of Clogging: Proximal Intermediate Distal #1 Issue with ASR Wells (unconsolidated aquifers) = Clogging
- 8. Conventional Methods of Recharge • Down-Hole Flow Control Valve – Main Goal- Eliminate Air Entrainment – Regulate Injection Flow – Recharge Rate 50% of Production Rate • Down-Hole Flow Control Valve Issues – Not Operator Friendly – Valve Located Down-Well – Most Systems Cannot Determine Percent Opening – Valve has Potential to Leak – When Valve Fails- Requires the Valve and Pump to be Pull Out of Well- Extended Down Period. – Obtaining Manufacturer Replacement Parts May Require Long-Lead Time
- 9. Reverse Siphon Method Our Goals & Priorities – Reduce Air-Entrainment & Agents of Clogging – All Equipment Serviceable & Not Exotic – Fewer Mechanical Components = Lower O&M Costs – Backwash Operations Achieved with Permanent Pump – Automation-Reduce Labor Force Oversight – Increase Recharge Utilization
- 11. Recharge Start-Up 2,000 gpm 500 gpm 0 gpm 2,500 gpm 2,000 gpm
- 12. Recharge Start-Up 2,000 gpm 500 gpm 0 gpm 2,500 gpm 2,000 gpm
- 13. Recharge Start-Up 400 gpm 2.100 gpm 2,000 gpm 2,500 gpm 2,400 gpm
- 14. Recharge Start-Up -1,900 gpm 2,000 gpm 2,400 gpm 100 gpm
- 15. Recharge Start-Up 0 gpm 1,900 gpm -1,900 gpm (Recharge)
- 16. Advancements in ASR Well Design • Utilize Glass Beads as a Filter Pack Media: – Enhance recharge and recovery efficiencies – Compared SiLi Beads 2.4-2.9mm versus Silica Sand 6 x 9 – Direct Relation Between Sorting and Porosity (Beard and Weyl, 1973 & Nagtegaal, 1978)
- 17. Water Level- 435 feet Access Tube 0.075-inch slot for well screen Pump Setting- 614 feet Access Tube- 619 feet Pumping Rate: 1,540 gpm Injection Rate: 1,170 gpm SiLi Bead, Zone 3- 638-659, 639-660 feet K= 36 ft/day Silica Sand, Zone 2- 680-701, 685-706 feet K= 28 ft/day Cave Creek Aquifer Storage and Recovery Well: As-Built 810 feet 501.5 feet 559-669 feet
- 18. 0 1 2 3 4 5 6 7 8 9 5/26/2015 7/15/2015 9/3/2015 10/23/2015 12/12/2015 1/31/2016 3/21/2016 Recovery: Formation Yield: Specific Capacity (gpm/ft): SiLi Beads (638-659, 639-660 ft) vs. Silica Sand (680-701, 685-706 ft) SiLi Bead (638-659 feet) Silica Sand (680-701 feet) SiLi Beads (639-660 feet) Silica Sand (685-706 feet) Initial Specific Capacity (6/18/12)- 7.46 gpm/ft Initial Specific Capacity (6/18/12)- 4.13 gpm/ft SpecificCapacity(gpm/ft) Specific capacity of glass beads is 1.8 to 2.4 time’s greater silica sand
- 19. 0 2 4 6 8 10 12 14 16 5/26/2015 7/15/2015 9/3/2015 10/23/2015 12/12/2015 1/31/2016 3/21/2016 Recharge: Formation Yield: Specific Capacity (gpm/ft): SiLi Beads (638-659, 639-660 ft) vs. Silica Sand (680-701, 685-706 ft) SiLi Bead (638-659 feet) Silica Sand (680-701 feet) SiLi Beads (639-660 feet) Silica Sand (685-706 feet) SpecificCapacity(gpm/ft) Glass bead specific capacity 3 to 9 times greater Silica Sand specific capacity decline 2 to 3 gpm/ft
- 20. 0 5 10 15 20 25 30 35 40 45 50 55 60 0 100 200 300 400 500 600 SpecificCapacity-GPMperFootChange Pumping and Recharge Cycle Sequence (# of Cycles) Cave Creek Water Reclamation Plant ASR Well-1 Specific Capacity BW Pump SC Recharge SC Cycle End Recharge SC 6/19/2015 6/29/2015 10/1/2015 10-day Recharge Cycle 1,155 gpm Injection Rate 1,170 gpm Injection Rate 31% Injection Rate Reduction 800 gpm injection rate with 4.66 gpm/ft (SC) 4/3 day Recharge Cycles 7-day Recharge Cycles 88% Clogging Event 2.5 years of operations
- 21. Conclusions • Reverse Siphon- Alternative Recharge Method – Operator Friendly • Well Development through the Permanent Pump Assembly • Efficient Backwashing Operations through Automation – Eliminates Air Entrainment and Reduces Clogging Agents – Capital Cost for the Surface Recharge Valve is less than Conventional Flow Controls Valves – Lower O&M Costs – Cost Effective (Well Rehabilitation Savings $110K to $150K/year per well) – Reliable and Stable Recharge Operations
- 22. Conclusions • Glass Beads- Alternative Filter Pack – Improved Hydraulics – More Efficient Backwashing Operations – Increase Efficiency 50-60 % for Recharge Operations – This Is The Tip Of The Iceberg…..
- 23. Questions Leonard Rice Engineers Gary M. Gin, R.G. – AZ & TX Vice President of AZ Operations 11811 North Tatum Blvd. Suite P-115, Phoenix AZ 85028 gary.gin@lrewater.com Cell-602-769-2889 Office- 602-296-7093 LRE Water LLC Mike Keester, R.G. - TX Hydrogeologist/Project Manager 1101 Satellite View, Suite 301, Round Rock TX 78665 mike.keester@lrewater.com Cell- 512-962-7660 Office-512-736-6485