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Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane River Conference
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Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Dec 17, 2015

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Page 1: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Expansion and Update of the City of Spokane and SAJB Spokane

Valley Rathdrum Prairie Aquifer Model

Doug GreenlundCity of SpokaneMarch 26, 2013

2013 Spokane River Conference

Page 2: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Made Possible by

• Grant Funding from the Washington State Department of Health

Source Water Protection Program

• Funding from the Spokane Aquifer Joint Board

• City of Spokane Utilities Division

• GSI Water Solutions: John Porcello (hydrogeology and modeling lead), Matt Kohlbecker (stormwater and pollutant transport), Ari Petrides (modeling, GIS)

Page 3: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Outline

• Description of MicroFEM®

• Similarities and differences with the Bi-State Model

• Similarities and differences with the previous model

• Examples of outputs

Page 4: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

The Model

• MicroFEM®

• Steady State

• Finite Element mesh

• Uses annual averages for pumping, recharge, boundary conditions

Page 5: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Model Development History

• 1994 City of Spokane worked with CH2MHill to develop Wellhead Protection and finite element model

• 2000 SAJB version of the model

Page 6: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

The Project

• Expand the Model to avoid truncation of capture zones at the state line

• Update the model with current information

Page 7: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

New Aquifer Boundary

• Original model ended at the state line. Key element of entire project

• New model based on Bi-State boundary but includes Hoodoo Valley and lower Hangman Creek

• Removed Green Street Knoll

Page 8: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Model Boundary Comparison

Page 9: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Developed New Grid

• Mesh on 550 foot centers

• 80 to 100 nodes per square mile

• Bi-State model is 16 grids per square mile

• Original model has about 25 nodes per square mile

• 44,703 nodes in model

• Tighter spacing around wells

Page 10: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Comparison of Grid and Mesh near Consolidated Irrigation District Well 2

Bi-State Model Square Grid Cells (Black) MODFLOW

Finite Difference

¼ mile

City/ SAJB ModelFlexible mesh (Blue)( Micro FEM®)Finite Element

2C 2A

2B

Page 11: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Aquifer Base and Aquifer Level

• Developed the base of the aquifer and assigned a value to each node

• Used contour maps to develop the aquifer surface elevation

Page 12: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Model Groundwater Elevations

Page 13: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Aquifer Thickness

• This is the difference between the base elevation and the average surface level

• Model has three layers– First layer down to 100 feet

– Second layer 100 to 200 feet

– Third layer below 200 feet

Page 14: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Thickness and Bedrock

• Uses three layers to simulate groundwater flow

– The USGS Bi-State model used just one layer, except in Hillyard Trough (3 layers north of Spokane city limits)

– Pain-staking effort to resolve issues with Bi-State model files

• Electronic files: Too thick just east of state line,

and too thin between state line and City of Spokane

• Published maps: Found internal inconsistencies

(saturated thickness did not match water table and basement)

• Localized change to USGS representation of basement bedrock and SVRP thickness near downtown Spokane (per City and Ecology)

Page 15: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.
Page 16: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Transmissivity and Vertical Resistivity

• Used original data on the Washington portion

• Bi-State model in Idaho

• Transmissivity used to define internal boundaries such as Pines Road Knoll

• Vertical Resistivity used to create layers

Page 17: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Boundary Conditions• Annual Averages

• Set a fixed groundwater elevation for Long Lake based on the average from the Bi-State Model

• Tributary inflow from 37 areas in Washington and 37 in Idaho

• Stage elevations for Spokane River from the original MicroFEM model.

• Stage elevations for the Little Spokane River and Lake Pend Oreille are from the Bi-State Model

Page 18: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Pumping Rates

• Used existing model data for Washington with updates from purveyors

• Extracted data from Bi-State model and information from USGS for certain wells in Idaho

• Idaho well locations provided by Idaho DEQ

Page 19: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Pumpage and Recharge

Pumping and areal recharge are now separated!– Lumped together into single term in Bi-State model

Bi-State model pumping =(1) Actual pumping minus(2) Septic system infiltration minus(3) 40% of outdoor-applied water in urban areas minus(4) 40% of outdoor-applied water on irrigated fields

– Difficult to change pumping in Bi-State model: requires decisions about whether (and how) to change recharge– Difficult and time-consuming to separate, but GSI Water Solutions did it!

Page 20: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Wellhead Protection Areas

• Backward Particle tracking

• Based on Purveyor supplied pumping rates

• Times of travel provided by purveyors

• There are Special Wellhead Protection Areas for 115 wells

Page 21: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Flowline Input Box

Page 22: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

City of Spokane Ray Street 2 Month Time of Travel

Interstate 90

Thor Freya

Page 23: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

City of Spokane Ray Street 2 Year Time of Travel in Blue

Argonne

Page 24: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.
Page 25: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Special Wellhead Protection Areas in ArcGIS

Page 26: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Infiltration

• MicroFEM®

is well suited to analyze infiltration such as stormwater

• Forward particle tracking

• The model has areas with nodes spaced with infiltration in mind

Page 27: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

SAJB and Bi-State Model Grids at Chester Creek

27

Chester Creek Recharge Basins

Model ID #3

Model ID #7

WD#3 Browns Park

Modern Electric #9

Model ID #5

Model ID #1 and #6

WD#3 20th & Balfour

Page 28: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Influence of 25-Year Infiltration Events at the Chester Creek And Saltese Recharge Basins

Saltese Flats / Shelly Lake Recharge Basin

Chester Creek Recharge Basins

25-Year Event Infiltration Rates

42,941 gpm (95.7 cfs) Chester Creek

65,045 gpm (144.9 cfs)Saltese Flats / Shelly Lake

28

1 Year1 Year

Page 29: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Influence of 25-Year Infiltration Events at the Chester Creek And Saltese Recharge Basins

Saltese Flats / Shelly Lake Recharge Basin

Chester Creek Recharge Basins

29

2 Years2 Years25-Year Event

Infiltration Rates

42,941 gpm (95.7 cfs) Chester Creek

65,045 gpm (144.9 cfs)Saltese Flats / Shelly Lake

Page 30: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Influence of 25-Year Infiltration Events at the Chester Creek And Saltese Recharge Basins

Saltese Flats / Shelly Lake Recharge Basin

Chester Creek Recharge Basins

30

3 Years3 Years25-Year Event

Infiltration Rates

42,941 gpm (95.7 cfs) Chester Creek

65,045 gpm (144.9 cfs)Saltese Flats / Shelly Lake

Page 31: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Influence of 25-Year Infiltration Events at the Chester Creek And Saltese Recharge Basins

Saltese Flats / Shelly Lake Recharge Basin

Chester Creek Recharge Basins

31

5 Years5 Years25-Year Event

Infiltration Rates

42,941 gpm (95.7 cfs) Chester Creek

65,045 gpm (144.9 cfs)Saltese Flats / Shelly Lake

Page 32: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Influence of 25-Year Infiltration Events at the Chester Creek And Saltese Recharge Basins

Saltese Flats / Shelly Lake Recharge Basin

Chester Creek Recharge Basins

32

7 Years7 Years25-Year Event

Infiltration Rates

42,941 gpm (95.7 cfs) Chester Creek

65,045 gpm (144.9 cfs)Saltese Flats / Shelly Lake

Page 33: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Influence of 25-Year Infiltration Events at the Chester Creek And Saltese Recharge Basins

Saltese Flats / Shelly Lake Recharge Basin

Chester Creek Recharge Basins

33

8 Years8 Years25-Year Event

Infiltration Rates

42,941 gpm (95.7 cfs) Chester Creek

65,045 gpm (144.9 cfs)Saltese Flats / Shelly Lake

Page 34: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Influence of 25-Year Infiltration Events at the Chester Creek And Saltese Recharge Basins

Saltese Flats / Shelly Lake Recharge Basin

Chester Creek Recharge Basins

34

10 Years10 Years25-Year Event

Infiltration Rates

42,941 gpm (95.7 cfs) Chester Creek

65,045 gpm (144.9 cfs)Saltese Flats / Shelly Lake

Page 35: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Resources

• Technical Memorandums for the entire project are on line at greenspokane.org

• John Porcello will be presenting at the 9th Washington Hydrogeology Symposium “Wellhead Protection and Stormwater Recharge in the Washington Portion of the Spokane Valley - Rathdrum Prairie Sole Source Aquifer”

Page 36: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Conclusions• Differs Functionally from Bi-State Model– Steady State

– Pumping and Recharge are Separate

– Finer grid

• Improvements from 2000 version– Expanded Boundary

– Finer mesh

– Different Boundary Conditions

Page 37: Expansion and Update of the City of Spokane and SAJB Spokane Valley Rathdrum Prairie Aquifer Model Doug Greenlund City of Spokane March 26, 2013 2013 Spokane.

Doug Greenlund

March 26, 2013

Thank You

Expansion and Update of the City of Spokane and SAJB Spokane

Valley Rathdrum Prairie Aquifer Model