Big Sky Wastewater Facility Plan Update

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

4. Calculated irrigation Disposal capacity(Million Gallons per year) * 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= 178.4 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

6. Growth Projections 218 MGY 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 • Large Pond = 60.1 MG • Small Pond = 19.6 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 = 159.7 MG

10. Existing & Future storage • Meadow Village • Large Pond = 60.1 MG • Small Pond = 19.6 MG • SBR Effluent =8.2 MG (with piping change) • Total Storage = 87.9 MG Yellowstone Mountain Club • Existing = 80 MG • Future = 50 MG • Total Storage = 130 MG Grand Total Existing and Future = 217.9 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 131.8 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.

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)

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 0.923 in 2014 but has been around 0.7 MGD in prior years • Third basin needed by 2021, start planning by 2018.

18. Effluent Quality

21. Cold Weather impacts

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