HomeMy WebLinkAbout23O - Wastewater Report (Full)ATWELL SUITES
BOZEMAN, MT
WASTEWATER ENGINEERING REPORT
JUNE 2024
1.0 General Information
The following report is intended to document the wastewater flows anticipated from the proposed
Atwell Suites Hotel as well as detail existing flows from the Town Pump #7 C-Store and Carwash to
document capacity within the existing 8” PVC sewer main that will ultimately serve both properties.
The hotel project is being completed by the following entity:
Bozeman 7 RE LLC
PO Box 6000
Butte, MT 59701
2.0 Anticipated Hotel Wastewater Flows
The project will include the construction of a 104-room hotel building which will contribute new
wastewater flows to the existing City of Bozeman sewer system. With respect to design flows for the
hotel, we refer to Circular DEQ 4, Table 3.1-1. The typical wastewater generation from a hotel is
estimated at 48 gpd/guest. At capacity, we anticipate the 104-room hotel will have 208 guests (two
occupants per room). The average daily wastewater generation is calculated as 208 guests x 48 gpcd,
plus 12 employees @ 10 gpcd equaling 10,104 gpd or an average daily flow rate of 7.0 gpm. Using a
peaking factor of 4.133 (Per DEQ 2 Equation 10-1), the peak hourly flows are anticipated as 29.0
gpm.
2.1 Existing C-Store & Carwash Wastewater Flows
With respect to existing wastewater flows currently generated at the Town Pump #7 C-store and
carwash, we refer to the attached City of Bozeman water use records for the property. As shown in
the attached calculations, the highest recorded monthly water usage & anticipated wastewater
generation is approximately 21,504 gpd which equates to an average flow 14.9 gpm. Using a
conservative peaking factor of 4.5, the anticipated peak hourly wastewater generation is 67.2 gpm.
The anticipated peak hourly wastewater generation from the hotel property (29.0 gpm) added to the
peak hourly flow rate from the C-store and carwash is therefore 96.2 gpm.
3.0 Existing Sewer Main Capacity
The existing sewer main serving the C-store and carwash and proposed to serve the new hotel site
consists of an 8” SDR 35 PVC piping at a 0.47% slope. Considering an 8” PVC sewer main flowing
at 80% full flow and using an as-built slope of 0.47%, the existing main has a capacity of
approximately 386 gpm. As the anticipated flow contributing to the main is calculated as 96.2 gpm,
the existing main is shown to have adequate capacity to serve the new hotel development.
23O - Atwell Suites - Bozeman, MT
Wastewater Generation & Water Use Calculations
6/11/2024
Information (wastewater generation/water use):
104-Room hotel @ 2 guests per room & 48 gpd/guest:9984 gpd
12 Employees @ 10 gpd/employee 120 gpd
Total Domestic Use:10104 gpd
Additional Water Use from Irrigation (see below)
Estimated Population = 220 persons±
Wastewater Generation (Per DEQ 4 - Table 3.1-1)
Hotel Guests + Employees =10104 gpd (Average Daily Use)
Max Daily Water Use =23239 gpd*(*Max Day Factor = 2.3 per CoB Design Standards Section V.4)
Overall Domestic Flow Rates (WW Generation & Domestic Water Use)
Average Flow Rate 7.0 gpm
Peak Hourly Flow Rate 29.0 gpm
Max Day Domestic Water Use 16.1 gpm*
@ 220 persons, peaking factor =4.133
Assume water usage is similar to WW generation with additional Landscape Irrigation
Avg. Domestic Use Irrigation Use (see below)
Water Consumption =10,104 gpd +6300 gpd =16404 gpd (summer)
Landscaping Water Usage
39100 sf landscaping area
6300 gpd (Average irrigation use per day)
25 gpm (peak irrigation demand)
Note: Refer to Steiner Thuesen Landscaping Design for additional information
Peak Instantaneous Demand - Refer to Additional Calculations & Mechanical Eng. Fixture Unit Analysis
Peak Instant Demand:89.5 gpm
𝐷𝐷𝑃 2 𝐷𝑞𝑛 10 −1:𝐷𝑒𝑞𝑖𝑔𝑛𝑃𝑒𝑎𝑘𝐻𝑛𝑢𝑞𝑘𝑦𝐷𝑘𝑛𝑢
𝐷𝑒𝑞𝑖𝑔𝑛𝐴𝑢𝑒𝑞𝑎𝑔𝑒𝐷𝑘𝑛𝑢=(18 +𝑃)
(4 +𝑃)
23O - Atwell Suites Hotel
Existing C-Store & Carwash Water Records
Town Pump #7 C-Store - 1871 Baxter Lane
TP 1092 53190 1 HCF = 748 Gallons
Daily Peak Hourly
Start Date End Date Days Usage (HCF)Usage (gal)Usage (gpd)Avg gpm (4.5x Peak Factor)
3/6/2024 4/4/2024 29 41.7 31191.6 1076 0.75 3.36
2/5/2024 3/6/2024 30 45.8 34258.4 1142 0.79 3.57
1/3/2024 2/5/2024 33 46.3 34632.4 1049 0.73 3.28
12/6/2023 1/3/2024 28 36 26928 962 0.67 3.01
11/5/2023 12/6/2023 31 44.8 33510.4 1081 0.75 3.38
10/5/2023 11/5/2023 31 58.2 43533.6 1404 0.98 4.39
9/8/2023 10/5/2023 27 141.5 105842 3920 2.72 12.25 *Note: Includes LS Irrigation
8/3/2023 9/8/2023 36 729.9 545965.2 15166 10.53 47.39 *Note: Includes LS Irrigation
7/10/2023 8/3/2023 24 351.6 262996.8 10958 7.61 34.24 *Note: Includes LS Irrigation
6/1/2023 7/10/2023 39 97.1 72630.8 1862 1.29 5.82 *Likely include irrigation use (conservative)
5/3/2023 6/1/2023 29 63.6 47572.8 1640 1.14 5.13
4/4/2023 5/3/2023 29 41.4 30967.2 1068 0.74 3.34
Highest Use*1862 1.29 5.82
*Note: Highest Use calcs shown neglect months with substantial irrigation water use which does not contribute to WW flow
Town Pump #7 Carwash - 1871 Baxter Lane
CW 1710 135610 1 HCF = 748 Gallons
Daily Peak Hourly
Start Date End Date Days Usage (HCF)Usage (gal)Usage (gpd)Avg gpm (4.5x Peak Factor)
3/6/2024 4/4/2024 29 583.6 436532.8 15053 10.45 47.04
2/5/2024 3/6/2024 30 420.8 314758.4 10492 7.29 32.79
1/3/2024 2/5/2024 33 515.8 385818.4 11691 8.12 36.54
12/6/2023 1/3/2024 28 351.2 262697.6 9382 6.52 29.32
11/5/2023 12/6/2023 31 528.4 395243.2 12750 8.85 39.84
10/5/2023 11/5/2023 31 458.2 342733.6 11056 7.68 34.55
9/8/2023 10/5/2023 27 399.13 298549.24 11057 7.68 34.55
8/3/2023 9/8/2023 36 568.5 425238 11812 8.20 36.91
7/10/2023 8/3/2023 24 611.2 457177.6 19049 13.23 59.53
6/1/2023 7/10/2023 39 488.7 365547.6 9373 6.51 29.29
5/3/2023 6/1/2023 29 470.9 352233.2 12146 8.43 37.96
4/4/2023 5/3/2023 29 761.5 569602 19641 13.64 61.38
Highest Use 19641 13.64 61.38
gpd gpm Peak Hourly
Highest Monthly Use (C-Store)1862 1.29 5.82
Highest Monthly Use (Carwash)19641 13.64 61.38
Total 21504 14.93 67.20
23O - Atwell Suites Hotel
Existing 8" Sewer Main Capacity
5/22/2024
Open Channel Flow mannings n:
0.01 Glass, Copper, Plastic - Smooth
Trapezoid Geometry:0.012 Steel or Wood - smooth
Input:0.013 Painted Steel or coated cast iron
Calculated:0.014 uncoated steel, clay pipe
0.015 brick cement mortar, float fin. Concrete
Bot. Wdth b =feet 0.017 unfinished concrete
Side Sl z =feet 0.022 clean excavated earth
Depth y =feet 0.024 corrugated metal pipe
Slope S =ft/ft 0.05 earth with light vegetation
Mannings n ={see table}0.1 earth with heavy vegetation
A =0
WP =0
R =#DIV/0!
Q =#DIV/0!cfs
V =#DIV/0!fps
Circular Geometry:
D =0.67 ft
y =0.53 ft
S =0.0047 ft/ft
n =0.01 {see table}
=4.428594871 {calculated}
T =0.5336 {calculated}
A =0.299665823 {calculated}
WP =2.01053639 {calculated}
R =0.149047699 {calculated}
Q =0.860504555 cfs
Q =386.1944443 GPM
V =2.871547201 fps