Southern California Salinity Coalition TDS Trends Study Update for - - PowerPoint PPT Presentation

▶
southern california salinity coalition tds trends study
SMART_READER_LITE
LIVE PREVIEW

Southern California Salinity Coalition TDS Trends Study Update for - - PowerPoint PPT Presentation

Sep 08, 2023 119 likes •261 views

Southern California Salinity Coalition TDS Trends Study Update for the Basin Monitoring Program Task Force October 18, 2017 Daniel B. Stephens & Associates, Inc. Problem Statement 1. Evaluate the long-term trends for salinity in wastewater

slide-1
SLIDE 1

Daniel B. Stephens & Associates, Inc.

Southern California Salinity Coalition TDS Trends Study Update for the Basin Monitoring Program Task Force

October 18, 2017

slide-2
SLIDE 2

Daniel B. Stephens & Associates, Inc.

Problem Statement

  • 1. Evaluate the long-term trends for salinity in wastewater and

recycled water

  • 2. Assess how periodic droughts and various conservation

measures may influence these trends

  • 3. Primary Research Questions:
  • a. What portion of the increment from use (IFU) can be attributed to

water conservation measures?

  • b. If trends of conservation measures continue, what portion of the

IFU can be attributed to water conservation measures

slide-3
SLIDE 3

Daniel B. Stephens & Associates, Inc.

100 200 300 400 500 600 700 800 900 1,000

2007 2008 2009 2011 2012 2013 2015 2016 2017

TDS Concentration (Mg/L)

Temecula Valley Sewershed

Source Effluent Influent Temecula Valley Discharge Limit: 750 mg/L

Problem Statement

  • Increment from use (IFU)

typically ranges from 200 to 250 mg/L.

  • IFU can drive effluent

TDS above the discharge limit.

  • How much of IFU is due

to conservation measures?

slide-4
SLIDE 4

Daniel B. Stephens & Associates, Inc.

50 100 150 200 250 300 350 400 450 500 40 45 50 55 60 65 70 75 80 85 Increment from Use TDS (mg/L) Indoor Water Use (gpcd)

Salt Load = 0.17 pounds per capita per day Salt Load = 0.15 pounds per capita per day

1980 Indoor Water Use (77 gcpd) 2016 Indoor Water Use (52 gcpd)

Increase in TDS from MSLs from Indoor Use

slide-5
SLIDE 5

Daniel B. Stephens & Associates, Inc.

Regression Tree Analysis for Influent TDS

  • Indicates important explanatory

variables:

– Population (POP) – Source TDS (STDS) – Source Flow (SFLOW)

slide-6
SLIDE 6

Daniel B. Stephens & Associates, Inc.

Principal Component Analysis

PCA indicates an initial EMWD multiple regression model:

  • ITDS ˜ POP + STDS + SFLOW + PMDI +

IFLOW Backward stepping from the initial model resulted in removal of first SFLOW and second PMDI:

  • ITDS ˜ POP + STDS + IFLOW
slide-7
SLIDE 7

Daniel B. Stephens & Associates, Inc.

EMWD Multiple Regression Analysis

500 550 600 650 700 750 800 10/10/06 02/22/08 07/06/09 11/18/10 04/01/12 08/14/13 12/27/14 05/10/16 09/22/17

mg/L

ITDS Model

  • Variables:

– STDS: Source TDS – IGPCD: Influent per capita water use

  • R -squared = 0.979
  • Relative Importance

– STDS: 88.2 – IGPCD: 11.8

slide-8
SLIDE 8

Daniel B. Stephens & Associates, Inc.

EMWD Multiple Regression Analysis

500 550 600 650 700 750 800 10/10/06 02/22/08 07/06/09 11/18/10 04/01/12 08/14/13 12/27/14 05/10/16 09/22/17

mg/L

ITDS Model

500 550 600 650 700 750 800 10/10/06 02/22/08 07/06/09 11/18/10 04/01/12 08/14/13 12/27/14 05/10/16 09/22/17

mg/L

ITDS Model C_gpcd

  • Variables:

– STDS: Source TDS – IGPCD: Influent per capita water use

  • C_gpcd: Constant

water use of 66 gpcd (no conservation)

– IFU Difference: ~18mg/L

55 gpcd 66 gpcd

slide-9
SLIDE 9

Daniel B. Stephens & Associates, Inc.

IEUA Multiple Regression Analysis

500 550 600 650 700 750 800 10/10/06 02/22/08 07/06/09 11/18/10 04/01/12 08/14/13 12/27/14 05/10/16 09/22/17

mg/L

ITDS Model

  • Variables:

– STDS: Source TDS – IGPCD: Influent per capita water use

  • R -squared = 0.75
  • Relative Importance

– STDS: 67.2 – IGPCD: 32.8

400 420 440 460 480 500 520 540 560 07/24/98 04/19/01 01/14/04 10/10/06 07/06/09 04/01/12 12/27/14 09/22/17

mg/L ITDS Model

slide-10
SLIDE 10

Daniel B. Stephens & Associates, Inc.

IEUA Multiple Regression Analysis

500 550 600 650 700 750 800 10/10/06 02/22/08 07/06/09 11/18/10 04/01/12 08/14/13 12/27/14 05/10/16 09/22/17

mg/L

ITDS Model

400 420 440 460 480 500 520 540 560 07/24/98 04/19/01 01/14/04 10/10/06 07/06/09 04/01/12 12/27/14 09/22/17

mg/L ITDS Model

  • Variables:

– STDS: Source TDS – IGPCD: Influent per capita water use

  • C_gpcd: Constant

water use of 95 gpcd (no conservation)

– IFU Difference: ~20mg/L

400 420 440 460 480 500 520 540 560 07/24/98 04/19/01 01/14/04 10/10/06 07/06/09 04/01/12 12/27/14 09/22/17

mg/L ITDS Model C_pgcd

70 gpcd 95 gpcd

slide-11
SLIDE 11

Daniel B. Stephens & Associates, Inc.

Source TDS Indoor per capita water use Influent TDS

Source Flow Drought Index State Mandate % SPW Allocation Local Conservation State Mandate

Seasonal trends Long term conservation trends = Effluent TDS

Technology enhancements

slide-12
SLIDE 12

Daniel B. Stephens & Associates, Inc.

Summary

  • Unintended consequences from water conservation measures

– lower water quality (higher TDS) – less quantity of recycled water – less revenue – infrastructure O&M

  • Observation data from groups of sewering agencies rather than

individual WWTP is more reliable due to the following factors

– Population (city boundaries, sewershed boundaries) – Operations can divert flows from plant to plant

slide-13
SLIDE 13

Daniel B. Stephens & Associates, Inc.

Summary

  • Drought impacts both source water quality

and an agency’s source(s) of supply.

  • “...drought, and the conservation strategies

that are often enacted in response to it, both likely limit the role reuse may play in improving local water supply reliability.”