1. Big Sky Wastewater Facility Plan Update
Final Report
August 25, 2015

2. Updated Projected flow
Flows updated to include LMM and Spanish Peaks

3. Growth Projections
High rate 4.82%
Average rate 4.09%
Low Rate 3.36 %

4. Calculated irrigation Disposal capacity (Million Gallons per year)
Prior Calculated Capacities
Revised Capacities
Meadow Village Course
206*
YMC** 76
22-28
Spanish Peaks**
100.8
20-30
Total
382.8
YMC and Spanish Peaks based on preliminary design reports completed by Nicklin Earth and Water
Maybe high based on actual irrigation volumes currently being used
* Per DEQ approval
** Based on Design Reports

5. REASONS FOR DIFFERENCES
Percolation rates used
Spanish Peaks = 0.2 inches/hour (Based on SCS data)
YC = 2.0 inches/ hour (Based on SCS data)
Meadow Village = 1.58 inches/ hour (Based on perc tests)
Nitrogen uptake
Spanish Peaks= pounds/ acre
YC= 147 pound/acre
Meadow Village 108 pound/acre ( from irrigation)
Irrigation Period
Spanish Peaks and YC used 24 hours/day
Meadow Village used 6 hours/day
137 day growing season used for all three courses
Spanish Peaks and YC perc rates based on SCS published data. No percolation testing has been done on YC or Spanish Peaks to confirm
Irrigation Period; need to have a 3:1 dry- wet cycle to meet DEQ requirements. SP and YC calculation done using 24 hour per day
All courses use a 137 day irrigation period. It is unlikely that SP and YC would have the same irrigation period as the Meadow Village

6. Growth Projections 218 MGY 182 MGY High rate 4.82% Average rate 4.09%
Low Rate 3.36 %
182 MGY

7. Golf course Upgrades and recommendation
Do testing on the YC and SP courses to determine actual percolation rates

8. Storage requirements no winter disposal

9. Existing storage Meadow Village Yellowstone Mountain Club
Large Pond = MG
Small Pond = MG
Total Filtered Storage = 79.7 MG
SBR Effluent = 8.2 MG ( but effectively zero due to piping)
Yellowstone Mountain Club
80 MG
Total Existing Storage = MG

10. Existing & Future storage
Meadow Village
Large Pond = MG
Small Pond = MG
SBR Effluent = MG (with piping change)
Total Storage = MG
Yellowstone Mountain Club
Existing = 80 MG
Future = 50 MG
Total Storage = MG
Grand Total Existing and Future = MG
Storage Needs (no winter disposal)= 226 MG

11. Storage requirement with winter disposal
100,000 gallons per day of winter disposal

12. Need for Project
Projected Flows exceed current disposal capacity by 95.8 to MGY
Reduce the level of nutrients applied to the Meadow Village Couse to reduce impacts to the Middle Fork
Provide additional disposal to allow the District to exercise its water right on the West Fork.
Current disposal is 95.8 to MGY short of the projected full buildout flows

13. Alternatives considered for additional Disposal
1. Disposal on the west side of the Madison Range near Ennis. Estimated Cost $13.1 million
2. Construct purple pipe system for effluent reuse in Meadow Village area. Estimated Cost $5 million + treatment plant upgrades.
Could also be part of an expanded golf course irrigation
3. Indirect Potable Reuse
Deep Injection Wells (not considered viable)
Shallow injection Wells ( rough estimate $350,000 to $500,000 + advanced treatment $7-$9 million)
Additional study would be required to determine the actual volume that could be injected

14. Alternatives considered for additional Disposal
4. Subsurface Disposal (drainfields)
5. Surface Discharge to the Gallatin River during the winter
6. Snowmaking
7. Direct Potable Reuse

15. Winter Disposal Options
Subsurface drain fields or aquifer injection
Indirect Potable Reuse
Unlikely to meet all discharge needs
Aquifer injection- must meet primary drinking water standards or non-degradation requirements at discharge point
Additional treatment required
Surface discharge
Possible based on DEQ rules and non-degradation criteria

16. Existing treatment plant
Plant Capacity
Effluent Quality
Metering
Additional Process Monitoring
Ammonia and ORP probes for SBR’s and digesters
TSS meter for waste sludge to help control solids in system
Adding VFD’s to blower motors to control DO

17. Plant Capacity Design Capacity – Peak Day 1.3 MGD
Current Capacity – Peak Day 1.04 MGD
Cycle time increased to improve nitrogen removal
Current Peak Day in 2014 but has been around 0.7 MGD in prior years
Third basin needed by 2021, start planning by 2018.
Total cycle time =
4.8 hours
React
0.58 hours
Mixed fill
0.67 hours
Settling time
0.75 hours
React fill
1.74 hours
Decant time
1.07 hours
Total cycle time =
6 hours
React
1 hour
Mixed fill
Settling time
React fill
2 hours
Decant time

18. Effluent Quality

21. Cold Weather impacts
Improved monitoring for solids control.

22. Aeration control

23. Metering

24. Metering

25. Treatment plant upgrades
Add VFD drives to blowers
$216,000
Modify piping for SBR effluent storage pond
$187,000
Additional monitoring probes
District has already purchased
Additional work to resolve metering