A presentation on the Water Supply Plan & Hydrogeology of the Westside associated with the Rosemont Copper Project developed by the Erroll L. Montgomery & Associates, Inc. This presentation was given to the Forest Service, the Cooperating Agencies, and their contractors during technical transfer meetings in January 2009.

1. WATER SUPPLY PLAN &
HYDROGEOLOGY
“WESTSIDE PRESENTATION”
January 16, 2009
ERROL L. MONTGOMERY
& ASSOCIATES, INC.

2. PRESENTATION OUTLINE
1. Water Supply Plan
2. Test Well Drilling and Testing
Program
3. Local Residential Well Programs
4. Hydrogeology and Groundwater
Conditions
5. Groundwater Flow Modeling
ERROL L. MONTGOMERY & ASSOCIATES, INC.

3. WATER SUPPLY PLAN
ERROL L. MONTGOMERY & ASSOCIATES, INC.

4. RECENT GROUNDWATER PUMPING IN THE GREEN VALLEY-SAHUARITA AREA
Average of 90,300 acre-feet/year based on ADWR records, 2000-2006
SIERRITA MINE
(29,200 acre-feet/year)
Mining Use
Agriculture Use 42%
36%
TWIN BUTTES
FICO/ FARMERS WATER
COMPANY
(32,300 acre-feet/yr)
MISSION MINE
SAHUARITA & RANCHO
SAHUARITA
LAS QUINTAS SERENAS
COMMUNITY WATER
ARIZONA STATE LAND COMPANY
DEPT. TUCSON WATER
GREEN VALLEY DOMESTIC
(Corona de Tucson) Municipal Use
WATER 20%
Groundwater pumping shown as a percentage of total for large
users (>500 acre-feet per year) south of Township 15S.
ERROL L. MONTGOMERY & ASSOCIATES, INC.

5. GROUNDWATER PUMPING IN THE GREEN
VALLEY-SAHUARITA AREA WITH ROSEMONT
SIERRITA MINE
(Average of 95,300 acre-feet/year) (29,200 acre-feet/year)
Mining Use
(45%)
TWIN BUTTES
Ag. Use (34%)
MISSION MINE
FICO/ FARMERS WATER
COMPANY
(32,300 acre-feet/yr) SAHUARITA & RANCHO
SAHUARITA
LAS QUINTAS SERENAS
COMMUNITY WATER
COMPANY
TUCSON WATER
(Corona de Tucson)
ROSEMONT (permitted for 20 GREEN VALLEY DOMESTIC
years) WATER
Municipal Use
ARIZONA STATE LAND DEPT.
(21%)
Groundwater pumping shown as a percentage of total for large users
(>500 acre-feet per year) in area south of Township 16S. Source: ADWR,
2000 to 2006. Rosemont pumping of 5,000 acre-feet/year.
ERROL L. MONTGOMERY & ASSOCIATES, INC.

6. MAJOR KNOWN FUTURE GROUNDWATER
PUMPING IN GREEN VALEY-SAHUARITA AREA
1. Existing M&I
• Community Water Company
• Green Valley Domestic Water, Las
Quintas Serenas, Rancho Sahuarita
• Corona de Tucson (Tucson Water)
2. New M&I
• FICO – ag converting to M&I
• AZ State Lands – (14,980 AF/year)
3. Mining
• Asarco Mission Mine
• FMI Sierrita Mine
• Twin Buttes
• Rosemont
ERROL L. MONTGOMERY & ASSOCIATES, INC.

7. RECHARGE
IN TAMA
ERROL L. MONTGOMERY & ASSOCIATES, INC.

8. ROSEMONT TEST WELLS –
SAHUARITA AREA
Ø Two wells constructed to depths of 1,211
(RC-2) and 1,300 feet (E-1)
Ø Characterization of basin-fill sediments and
groundwater quality (geophysical and
lithologic logs)
Ø Pumping Test Results
Ø Transmissivity: 1,340 (RC-2); 2,680 (E-1) ft2/day
Ø Anticipated well production: 500-1,500 gpm
Ø Excellent groundwater quality
Ø TDS range 210 (RC-2) to 340 (E-1) mg/L
ERROL L. MONTGOMERY & ASSOCIATES, INC.

9. LOCATIONS OF RC-2 & E-1
ERROL L. MONTGOMERY & ASSOCIATES, INC.

10. SCHEMATIC OF EXPLORATION WATER
WELL E-1 AND LOGGING SUMMARIES
ERROL L. MONTGOMERY & ASSOCIATES, INC.

11. EXPLORATION
WATER
WELL E-1
ERROL L. MONTGOMERY
& ASSOCIATES, INC.

12. EXPLORATION WELL E-1 LOGGING SUMMARIES
ERROL L. MONTGOMERY & ASSOCIATES, INC.

13. SCHEMATIC OF PRODUCTION WATER
WELL RC-2 AND LOGGING SUMMARIES
ERROL L. MONTGOMERY & ASSOCIATES, INC.

14. PRODUCTION
WATER
WELL RC-2
ERROL L. MONTGOMERY
& ASSOCIATES, INC.

15. PRODUCTION WELL RC-2 LOGGING SUMMARIES
ERROL L. MONTGOMERY & ASSOCIATES, INC.

16. CORRECTED DRAWDOWN AND RECOVERY DATA FOR
PUMPED WELL E-1 DURING CONSTANT-DISCHARGE
PUMPING TEST
-10
EXPLANATION
CORRECTED DRAWDOWN AND RESIDUAL DRAWDOWN, IN
PREPUMPING WATER LEVEL 226.67 FEET BELOW LAND SURFACE
PUMPING STARTED 13:05 MARCH 23, 2007
PUMPING STOPPED 13:05 MARCH 24, 2007
AVERAGE PUMPING RATE 312 GALLONS PER MINUTE
CORRECTED DRAWDOWN AND RESIDUAL DRAWDOWN, IN FEET
TRANSMISSIVITY (DRAWDOWN DATA) = 150,000 GALLONS PER DAY PER FOOT
TRANSMISSIVITY (RECOVERY DATA) = 20,000 GALLONS PER DAY PER FOOT
RECOVERY
0 NOTE: DATA CORRECTED TO ACCOUNT FOR
REGIONAL WATER LEVEL RISE DURING TEST
FEET
10
Pump down from t = 48 min to t = 51 min
20
DRAWDOWN
1 10 100 1,000 10,000
TIME, IN MINUTES, AFTER PUMPING STARTED and RATIO t/t' (t - TIME AFTER PUMPING STARTED / t' - TIME AFTER PUMPING STOPPED)
TIME, IN MINUTES, AFTER PUMPING STARTED AND RATIO t/t’ (time after pumping started /
time after pumping stopped)
FIGURE 4. GRAPH OF CORRECTED DRAWDOWN AND RECOVERY DATA FOR PUMPED WELL E-1
DURING CONSTANT-DISCHARGE PUMPING TEST
ERROL L. MONTGOMERY & ASSOCIATES, INC.

17. DRAWDOWN AND RECOVERY GRAPH FOR PUMPED WELL
RC-2 DURING CONSTANT-DISCHARGE PUMPING TEST
0
RECOVERY
DRAWDOWNDRAWDOWN AND RESIDUAL DRAWDOWN, IN FEET FEET
50
Transmissivity = 10,100 gpd/ft
AND RESIDUAL DRAWDOWN, IN
Theis (1935) Straight-Line Recovery Method
100
Transmissivity = 9,200 gpd/ft
Cooper and Jacob (1946) Straight-Line Drawdown Method
DRAWDOWN
150
200
EXPLANATION
250
PREPUMPING WATER LEVEL 259.27 FEET BELOW LAND SURFACE
PUMPING STARTED 08:00 NOVEMBER 12, 2007
PUMPING STARTED 08:00 NOVEMBER 13, 2007
AVERAGE PUMPING RATE 1,046 GALLONS PER MINUTE
300
1 10 100 1,000 10,000
TIME, IN MINUTES, AFTER PUMPING STARTED and RATIO t/t' (time after pumping started / time after pumping stopped)
TIME, IN MINUTES, AFTER PUMPING STARTED AND RATIO t/t’ (time after pumping started /
time after pumping stopped)
ERROL L. MONTGOMERY & ASSOCIATES, INC.

18. GROUNDWATER MONITORING
PROGRAM
Ø GIS database of ~200
registered wells and
~535 tax parcels in
monitoring area
Ø United Sahuarita Well
Owners picked 11
monitoring locations
Ø Water quality sampling
Ø Continuous water level
monitoring
ERROL L. MONTGOMERY & ASSOCIATES, INC.

19. GROUNDWATER MONITORING PROGRAM
ERROL L. MONTGOMERY & ASSOCIATES, INC.

20. Access to ADWR “realtime” data
Ø ADWR equipped
both Rosemont with
monitoring and relay
equipment
Ø Water level data
available at
www.azwater.gov
Ø Continuous,
realtime
ERROL L. MONTGOMERY & ASSOCIATES, INC.

21. WELL OWNER PROTECTION
PROGRAM
Ø Letter of Intent signed in July
2008
Ø Well must be registered with
ADWR
Ø Unique program, details are still
being developed
ERROL L. MONTGOMERY & ASSOCIATES, INC.

22. WEST SIDE HYDROGEOLOGY
Sahuarita
Heights
ERROL L. MONTGOMERY & ASSOCIATES, INC.

23. WEST SIDE HYDROGEOLOGY
q Groundwater occurs in basin-fill deposits
q Hydrogeologic Units
Ø Ft. Lowell Formation (dry in Sahuarita Heights)
Ø Tinaja beds (principal aquifer)
q Silty sand with minor gravelly zones
q Depth to water 200 to 250 feet
Ø Substantially deeper during irrigation season
q Groundwater flow toward northwest
q Water level trends over time
Ø Wells in study area produce from a few to
more than 2,000 gpm
ERROL L. MONTGOMERY & ASSOCIATES, INC.

24. GO TO CLICKABLE
HYDROGRAPHS

25. WEST SIDE HYDROGEOLOGY
ERROL L. MONTGOMERY & ASSOCIATES, INC.

26. WEST SIDE HYDROGEOLOGY
ERROL L. MONTGOMERY & ASSOCIATES, INC.

27. WEST SIDE
GROUNDWATER FLOW MODEL
q Began with ADWR Tucson AMA
Groundwater Model
Ø Numerical Basin-Wide Model
Ø MODFLOW Software
Ø Half-Mile Grid Cell Spacing
Ø Three Layers
Ø Simulation Periods
Ø 1940 – 1999 Pre-development and Transient
Ø 2000 – 2024 Predictive
ERROL L. MONTGOMERY & ASSOCIATES, INC.

28. WEST SIDE
GROUNDWATER FLOW MODEL
q Refinement of Model Following Data
Evaluation
Ø Update Groundwater Pumpage
Ø Evaluate & Modify Groundwater
Recharge
Ø Aquifer Parameters from Drilling &
Testing
ERROL L. MONTGOMERY & ASSOCIATES, INC.

29. WEST SIDE
GROUNDWATER FLOW MODEL
q Pumping Updates - historic
Ø Recent Updates Provided by ADWR for
2000 – 2006
Ø Others
q Recharge Updates – historic
Ø Pima Mine Road
Ø Effluent Recharge
Ø Santa Cruz River
Ø Mine Tailings

30. WEST SIDE
GROUNDWATER FLOW MODEL
q Results of Model Calibration
Ø Overall match in study area
Ø Match in Sahuarita Heights area
ERROL L. MONTGOMERY & ASSOCIATES, INC.

31. LOCATIONS OF
CALIBRATION HYDROGRAPHS
ERROL L. MONTGOMERY & ASSOCIATES, INC.

32. ERROL L. MONTGOMERY & ASSOCIATES, INC.

33. ERROL L. MONTGOMERY & ASSOCIATES, INC.

34. ERROL L. MONTGOMERY & ASSOCIATES, INC.

35. ROSEMONT WEST PLAN MAP
ERROL L. MONTGOMERY & ASSOCIATES, INC.

36. WEST SIDE
GROUNDWATER FLOW MODEL
q Rosemont Water Supply Simulations
Ø Rosemont Pumping 5,000 AF/year for 20
years – through 2031
Ø Future Pumpage by Other Groundwater
Users
Ø Future Recharge at USFs and WWTPs
ERROL L. MONTGOMERY & ASSOCIATES, INC.

37. WEST SIDE
GROUNDWATER FLOW MODEL
q Pumping Updates - future
Ø FICO
Ø ASLD
Ø Mission Wellfield
Ø Rancho Sahuarita
Ø Mining
Ø Others
q Recharge Updates – future
Ø Pima Mine Road
Ø Santa Cruz River
Ø Others

38. WEST SIDE
GROUNDWATER FLOW MODEL
q Model Projections - Pending
Ø Impacts to Regional Groundwater Levels
Ø Impacts to Local Domestic Wells
Ø Refined Local Grid Analysis