Groundwater Management Program Update Groundwater Level Monitoring - - PowerPoint PPT Presentation

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Groundwater Management Program Update Groundwater Level Monitoring - - PowerPoint PPT Presentation

May 20, 2023 92 likes •293 views

Groundwater Management Program Update Groundwater Level Monitoring Groundwater Quality Issues Update 30 25 MW - AB4 20 15 10 5 0 -5 -10 -15 -20 1/1/2012 12/31/2012 12/31/2013 12/31/2014 12/31/2015 12/30/2016 12/30/2017

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SLIDE 1

Groundwater Management Program Update

  • Groundwater Level Monitoring
  • Groundwater Quality Issues Update
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SLIDE 2
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5 10 15 20 25 30 1/1/2012 12/31/2012 12/31/2013 12/31/2014 12/31/2015 12/30/2016 12/30/2017 12/30/2018 12/30/2019

MW - AB4

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SLIDE 3
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5 10 1/1/2012 12/31/2012 12/31/2013 12/31/2014 12/31/2015 12/30/2016 12/30/2017 12/30/2018 12/30/2019

MW Lone Oak

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SLIDE 4
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5 10 1/1/2012 12/31/2012 12/31/2013 12/31/2014 12/31/2015 12/30/2016 12/30/2017 12/30/2018 12/30/2019

MW - N28

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SLIDE 5
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5 10 15 20 25 30 1/1/2012 12/31/2012 12/31/2013 12/31/2014 12/31/2015 12/30/2016 12/30/2017 12/30/2018 12/30/2019

MW - 6

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SLIDE 6
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5 10 1/1/2012 12/31/2012 12/31/2013 12/31/2014 12/31/2015 12/30/2016 12/30/2017 12/30/2018 12/30/2019

MW - Chuckwagon

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SLIDE 7
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5 10 15 20 25 30 1/1/2012 12/31/2012 12/31/2013 12/31/2014 12/31/2015 12/30/2016 12/30/2017 12/30/2018 12/30/2019

MW - 4

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SLIDE 8

MW-4 Monitoring Well Stage Gage

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SLIDE 9

5 10 15 20 25 30 35 2/1/2019 3/1/2019 4/1/2019 5/1/2019 6/1/2019 7/1/2019 8/1/2019

Feet

Elevation of Water

H St River Stage MW4

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SLIDE 10

40 45 50 55 60 65 70 2/1/2019 2/16/2019 3/3/2019 3/18/2019 4/2/2019 4/17/2019 5/2/2019 5/17/2019 6/1/2019 6/16/2019 7/1/2019 7/16/2019 7/31/2019

Temperature (F)

AWB MW4

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SLIDE 11

Water Quality Issues Update

Regional Contamination Issues Committee

  • Formed in 2004 in response to
  • Additional discovery of Aerojet contamination north of the American River
  • Claims by McClellan that recovery of groundwater levels due to conjunctive

use were interfering with remediation timetable (adding 100s of years)

  • Includes representatives of impacted water suppliers, regulators
  • verseeing sites, and responsible parties
  • Has met on a quarterly basis (mostly)
  • Intent has been to
  • find areas of common interest to improve efficiency for all participants
  • identify emerging regional water quality concerns early on
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SLIDE 12

Hexavalent Chromium

  • At recent State Water Board Division of Drinking Water Advisory

Group meeting, staff reported:

  • An economic feasibility white paper and public workshops expected in

October or November

  • Informal rulemaking on maximum contaminant level in late 2019 or early

2020

  • Formal rulemaking in late 2020 or early 2021
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SLIDE 13

Aerojet-Related Contaminant Plumes

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SLIDE 14
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SLIDE 15

1,2,3-TCP Maximum Contaminant Levels Exceedances Based on 2018 Sampling

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SLIDE 16

PFAS

  • Per- and polyfluoroalkyl substances (PFAS)
  • Human-made fluorinated compounds in use since 1940s
  • Manufactured in US until early 2000s
  • Several thousand PFAS compounds exist
  • Used to make materials resistant to stains, water-proof, and non-stick
  • Also used in fire suppression (fire-fighting foams)
  • Extremely persistent and resistant to typical environmental breakdown,

so found in air, soil, and water

  • Also accumulates in human body, so being found in wastewater

treatment plants

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SLIDE 17

PFAS continued

  • Testing ordered in water systems between 2013 and 2015 as part of

Unregulated Contaminant Monitoring Rule (UCMR) 3

  • PFAS of current concern include Perfluorooctanoic acid (PFOA),

Perfluorooctanesulfonic acid (PFOS)

  • No current drinking water standard, but US EPA established a lifetime

Health Advisory Level (HAL) for PFOA and PFOS of 70 nanograms/liter (or parts per trillion)

  • State Water Board (SWB) adopted the US EPA HAL as the California

Response Level (RL). When the RL is exceeded, and concentrations cannot be reduced below the RL, DDW recommends removing the source from service

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SLIDE 18

PFAS continued

  • The SWB established Notification Levels (NL) of 14 ng/L for PFOA and 13

ng/L for PFOS in 2018. When the NLs are exceeded, the Division of Drinking Water (DDW) recommends that the source be removed from service and treated

  • SWB has ordered additional sampling in 2019 for drinking water wells

within 2 miles of an airport, 1 mile of a municipal landfill, or 1 mile of a well with a UCMR3 detection

  • 32 wells in Sac County ordered to test
  • Results expected within next few months
  • DDW recommending lowering RL for PFOA to 10 ng/L and NL to 5.1 ng/L
  • DDW recommending lowering RL for PFOS to 40 ng/L and NL to 6.5 ng/L