HomeMy WebLinkAbout008.02 Appendix G.3 - Offsite Sewer Flow Estimates
BOZEMAN, GREAT FALLS, KALISPELL & SHELBY, MT | SPOKANE, WA | LEWISTON, ID | WATFORD CITY, ND | MEDIA, PA
406.586.0277
tdhengineering.com
234 East Babcock Street
Suite 3
Bozeman, MT 59715
MEMORANDUM
Date: November 27, 2024 TDH Job No.: B24-005
To: Simon Lindley - City of Bozeman Engineering Department
From: Cody Croskey, PE
Subject: 302 E. Mendenhall - Boutique Hotel Mendenhall
Offsite Sewer Flow Estimates
Below are the offsite sewer flow estimates for the Boutique Hotel Mendenhall project and
the existing parcels between the hotel and the 10-inch sewer line in N. Bozeman Avenue.
Estimates are being provided using two methods referencing information in the 2015
Wastewater Facilities Plan. Method 1 uses the existing land use categories (Table 2-12) to
estimate the current wastewater flow rates for parcels with existing buildings. Method 2
uses wastewater flow rates based on B-3 zoning (Table 2-13) assuming these parcels,
including the vacant lots, may be redeveloped in the future. The results from both methods
are summarized below with supporting calculations attached.
Estimated Offsite Sewer Flows:
Method 1
(Existing Land Use)
Method 2
(Future Land Use B-3)
New Hotel Building = 5,680 (GPD) 5,680 (GPD)
Other Contributing Parcels = 2,364 (GPD) 6,540 (GPD)
Lot Infiltration = 389 (GPD) 389 (GPD)
Total Daily Flow = 8,432 (GPD) 12,609 (GPD)
Peak Hour Demand = 23.8 (GPM) 35.5 (GPM)
Note, these estimates may be somewhat conservative for determining how much existing
wastewater flow will be switching to the N. Bozeman Avenue sewer line from the N. Rouse
Avenue sewer line. At most it would be the 2,364 GPD determined by Method 1 for the
existing buildings west of the hotel site, however several record drawings indicate that
some of these buildings may already have sewer services connecting to the 10-inch sewer
main in N. Bozeman Avanue.
tdhengineering.com
PAGE NO. 2 NOVEMBER 27, 2024
Please let me know if you have any questions or require additional information.
Sincerely,
Cody Croskey PE
Civil Engineer
TD&H ENGINEERING
Attachments
Offsite Sewer Flow Calculations
Contributing Parcel Map
I:\2024\BOZ\B24-005 BHM Mendenhall\05_DESIGN\OFFSITE SEWER\Preliminary Sewer FLOW ESTIMATES.DOC
Miles
0.0 1,128
This product is for informational purposes and may not have been prepared for, or be suitable for legal, engineering, or
surveying purposes. Users of this information should review or consult the primary data and information sources to
ascertain the usability of the information. Feet
1310
Legend
66
Location
131
11/27/2024
Created By:
Created For:
Date:
Title
Manholes
Abandoned Mains
Force Mains
Gravity Mains
Street Names
City Limits
World Imagery
Low Resolution 15m Imagery
High Resolution 60cm Imagery
High Resolution 30cm Imagery
Citations
30cm Resolution Metadata
OFFSITE SEWER - CONTRIBUTING PARCELS
New Hotel Site
0.41 Acres
Contributing Parcels
1.25 Acres
Contributing Parcels
0.93 Acres
Boutique Hotel Mendenhall
Offsite Sewer Main Replacement
Date: 11.27.24
Sewer Flow Estimates
Method 1: New Hotel + Existing Land Use Categories
Average Daily Flow - New Hotel Building:
New Hotel Use:
Rooms =71
Lot Size =0.41 Acres
Average Demand per Room =80.0 Gal./Day/Room
Average Day Demand =5,680 GPD
Average Daily Flow - Remaining Parcels (2015 Wastewater Facilities Plan Table 2-12):
Parcel ID Parcel Size
(Acres)
06-0799-07-2-13-64-0000 0.32
06-0799-07-2-13-58-0000 0.16
06-0799-07-2-13-52-0000 0.08
06-0799-07-2-13-54-0000 0.10
06-0799-07-2-13-46-0000 0.13
06-0799-07-2-13-50-0000 0.14
06-0799-07-2-20-20-0000 0.48
06-0799-07-2-20-21-5001 0.15
06-0799-07-2-20-21-5002 0.14
06-0799-07-2-20-25-0000 0.19
06-0799-07-2-20-28-0000 0.29
Total =2.18
Infiltration:
Property Size =2.59 acres
Infiltration Flow =389 GPD (150 gpd/acre per COB Design Standards)
Peak Sewer Flow:
Average Day Demand =8,044 GPD (total domestic flow)
Equivalent Population =125 Persons (total flow / 64.4 gpcd - from 2015 Wastewater Plan)
P =0.1249 (population/1,000)
Peaking Factor =4.22
Peak Domestic Sewer Demand =33,910 GPD (avg. day demand)*(peaking factor)
+ Infiltration Flow =389 GPD (not peaked)
Total Peak Flow =34,299 GPD (peaked domestic flow + infiltration)
Peak Sewer Flow =23.82 GPM (peak flow)/(24 hrs/day)/(60 min/hr)
Commercial 1,000 480
Admin / Professional 1,000 150
Mixed Use 1,000 130
Vacant 0 0
Commercial 1,000 80
Mixed Use 1,000 100
Restaurant / Bar 3,500 1,124
Admin / Professional 1,000 160
0
Vacant 0 0
2,364
Admin / Professional 1,000 140
Vacant 0
Land Use Category
Wastewater
Flow Rate
(Gal/Acre/Day)
Average Daily Flow
(GPD)
(See Comparable Facility Data in
Site Plan Application)
𝑄𝑚𝑎𝑥
𝑄𝑎𝑣𝑔
=18 +𝑠ℎ𝑛𝑠𝑠𝑎𝑛𝑑𝑠𝑛𝑑𝑛𝑑𝑛𝑛𝑙𝑑1/2
4 +𝑠ℎ𝑛𝑠𝑠𝑎𝑛𝑑𝑠𝑛𝑑𝑛𝑑𝑛𝑛𝑙𝑑1/2
Boutique Hotel Mendenhall
Offsite Sewer Main Replacement
Date: 11.27.24
Sewer Flow Estimates
Method 2: New Hotel + Future Land Use (Zoning)
Average Daily Flow - New Hotel Building:
New Hotel Use:
Rooms =71
Lot Size =0.41 Acres
Average Demand per Room =80.0 Gal./Day/Room
Average Day Demand =5,680 GPD
Average Daily Flow - Remaining Parcels (2015 Wastewater Facilities Plan Table 2-13):
Land Use Designation =B-3
Wastewater Flow Rate =3,000 GAL./AC./DAY
Drainage Basin Area (gross) =2.18 AC.
Average Daily Flow =6,540 GPD
Infiltration:
Property Size =2.59 acres
Infiltration Flow =389 GPD (150 gpd/acre per COB Design Standards)
Peak Sewer Flow:
Average Day Demand =12,220 GPD (total domestic flow)
Equivalent Population =190 Persons (total flow / 64.4 gpcd - from 2015 Wastewater Plan)
P =0.1898 (population/1,000)
Peaking Factor =4.16
Peak Domestic Sewer Demand =50,790 GPD (avg. day demand)*(peaking factor)
+ Infiltration Flow =389 GPD (not peaked)
Total Peak Flow =51,178 GPD (peaked domestic flow + infiltration)
Peak Sewer Flow =35.54 GPM (peak flow)/(24 hrs/day)/(60 min/hr)
(See Comparable Facility Data in
Site Plan Application)
𝑄𝑚𝑎𝑥
𝑄𝑎𝑣𝑔
=18 +𝑠ℎ𝑛𝑠𝑠𝑎𝑛𝑑𝑠𝑛𝑑𝑛𝑑𝑛𝑛𝑙𝑑1/2
4 +𝑠ℎ𝑛𝑠𝑠𝑎𝑛𝑑𝑠𝑛𝑑𝑛𝑑𝑛𝑛𝑙𝑑1/2