Approaches and techniques for evaluating artificial recharge

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Approaches and techniques for evaluating
artificial recharge

• Eric Reichard
• U.S. Geological Survey
• Western Governors Association
• Western States Water Council
• Irvine, CA November 14, 2006

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Overview

• Warren Basin unsaturated data collection
  nitrates
• Los Angeles
• Tracking recharge water chemical isotopes
• Monitoring reclaimed water tracer tests to
  evaluate pathogen removal
• Testing potential aquifer storage and recovery
  strategies simulation and visualization

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Warren Basin
Proposed recharge pond YVUZ-1
Septage affected site YVUZ-2
Golf course site YVUZ-3
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Rising water from spreading could intercept
nitrates in the unsaturated zone
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Change in NO3 Concentrations
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Los Angeles-Central and West Coast Basins
Spreading grounds
West Coast Barrier
Dominguez Gap Barrier
Alamitos Barrier
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Replenishment Water Types Costs

• Stormwater - FREE, but limited.
• Recycled water for spreading (21/af).
• Imported water for spreading (275/af).
• Recycled water for barriers (430/af).
• Imported water for barriers (545/af).
• Annual cost for 120,000 af of artificial
  replenishment water is 25 Million.

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Bacteriophage surrogates for human enteric
viruses

• PRD1 -- diameter of 62 nm

MS2 -- diameter of 25 nm
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Rapid reduction of bacterial viruses during
spreading.
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25-year aquifer storage and recovery scenarios in
West Coast Basin

• 10-year cycles
• 7 average-wet years -- store water
• Additional recharge and/or reduced pumpage
• 3 dry years extract water
• Additional pumpage

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Alternative 1A

• Years 1-7
• Selected pumpers shut off all pumping 30,000 afy
  (replace with imported water)
• Barrier injection equal to available recycled
  water quantity
• Years 8-10
• Selected pumpers extract at existing capacity
• Barriers continue injection equal to available
  recycled water quantity

Inglewood
Manhattan Beach
GSWC
Torrance
CWS
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Alternative 2A
Inglewood

• Years 1-7
• Selected pumpers shut off all pumping 30,000 afy
  (replace with imported water)
• Barrier injection is shut off
• Inland ASR injection to meet replenishment needs
• Years 8-10
• Selected pumpers pump at existing capacity
• No inland ASR injection

Manhattan Beach
GSWC
Torrance
CWS
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Scenarios 1A and 2aSimulated Water-level
Difference from Base Case

• 2A - higher inland water levels during storage
  period lower coastal water levels during
  extraction period

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Extent of Seawater Intrusion

• 2A - additional seawater intrusion

3.25 mi2
4.75 mi2
3.25 mi2
.75 mi2
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Approaches and techniques for evaluating
artificial recharge Summary

• Monitoring unsaturated zone
• Tracking recharge using isotopes
• Using surrogates to assess pathogen removal
• Modeling likely water- level and water-quality
  effects of aquifer storage and recovery

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Conjunctive Use Components
Conjunctive use components
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1. Reduction in N was 20-60, and varied under
   different environmental conditions.
2. About 1/3 reduction of organic carbon,
   independent of pre-existing conditions.
3. Total and fecal coliform bacteria distributions
   increased from nondetectable levels immediately
   before recharge with recycled water.

Recharge experiments Results
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• Bacteriophage are used as surrogates for human
  enteric viruses
• PRD1 is a double-stranded DNA somatic virus with
  a diameter of 62 nm
• MS2 is a single-stranded RNA male-specific virus
  with an average diameter of about 25 nm
• Bromide is used as a conservative tracer

Tracers
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Extent of Seawater Intrusion
1.75 mi2
1.50 mi2
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Incremental Intrusion (mi2) Difference from
Base Case
Scenario 1A Scenario 2A
Santa Monica Bay 1.5 3.0
San Pedro Bay -0.75 1.75
Net TOTAL 1.75 4.75
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RWQCB - Waste Discharge and Water Reclamation
Requirements (WD/WRR)

• The plant influent, recycled water, diluent
  water, blended water, and groundwater is
  monitored.
• Of particular importance is monitoring of the
  recycled water quality before it leaves the plant
  and after it is in the groundwater
• primary and secondary MCLs
• unregulated contaminants
• priority pollutants
• notification level chemicals (perchlorate, NDMA,
  1,4 dioxane)
• emerging contaminants pharmaceuticals, personal
  care, endocrine disrupters

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Saline Plume Map (based on highest concentrations
in available wells from 2002 2006)
El Segunda Blvd
Groundwater Flow Direction
Manhattan Beach Blvd
Sepulveda Blvd
Redondo Beach Blvd
190th
Crenshaw
Hawthorne
Torrance
Sepulveda
PCH
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Revised Scenarios
Year Period Annual Barrier Injection_WCBBDGB Annual Barrier Injection_WCBBDGB Annual Barrier Injection_WCBBDGB Annual Barrier Injection_WCBBDGB Annual Inland-ASR Wells Annual Inland-ASR Wells Annual Inland-ASR Wells Annual Inland-ASR Wells
    Base 1A 2A 2D Base 1A 2A 2D
7 2005-2011 31,950 17,289 0 0 0 0 24,750 9,750
3 2012-2014 31,950 17,289 0 0 0 0 0 9,750
7 2015-2021 31,950 17,289 0 0 0 0 24,750 9,750
3 2022-2024 31,950 17,289 0 0 0 0 0 9,750
5 2025-2029 31,950 31,950 31,950 0 0 0 0 9,750
Total   795,750 505,530 159,750 0  0   0 346,500 243,750  
Year Period Annual Pumpage_ Non-refinery Wells Annual Pumpage_ Non-refinery Wells Annual Pumpage_ Non-refinery Wells Annual Pumpage_ Non-refinery Wells Annual Pumpage_Refinery Wells Annual Pumpage_Refinery Wells Annual Pumpage_Refinery Wells Annual Pumpage_Refinery Wells
    Base 1A 2A 2D Base 1A 2A 2D
7 2005-2011 -30,138 0 0 -30,138 -19,600 -19,600 -19,600 -820
3 2012-2014 -30,138 -51,590 -51,590 -30,138 -19,600 -19,600 -19,600 -820
7 2015-2021 -30,138 0 0 -30,138 -19,600 -19,600 -19,600 -820
3 2022-2024 -30,138 -51,590 -51,590 -30,138 -19,600 -19,600 -19,600 -820
5 2025-2029 -30,138 -30,138 -30,138 -30,138 -19,600 -19,600 -19,600 -820
Total   -753,450 -460,230 -460,230 -753,450 -490,000   -490,000 -490,000 -20,500
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Process Flow Diagram
Sodium Hypochlorite
Compressed Air
MF Cleaning System
Title 22 Feed
Break Tank
Automatic Strainers
Microfiltration
Sulfuric Acid
Threshold Inhibitor
To LACSD
Reverse Osmosis
Ultraviolet light
RO Flush System
To Alamitos Barrier
Cartridge Filters
RO Cleaning System
Decarbonator
Final Product Clearwell Pump Station
To LACSD
Sodium Hydroxide
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Water Quality Comparison
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Simulated Head Difference from Base Scenario (2D
and 2A Revised)
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Alternative 2D

• Entire Period
• Eliminate barriers
• Seasonal injection through ASR wells to meet
  groundwater demands
• Supply refineries with recycled water

Inglewood
Manhattan Beach
GSWC
Torrance
CWS
Refineries
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Extent of Seawater Intrusion
6.25 mi2
4.75 mi2
0 mi2
3.25 mi2