HomeMy WebLinkAbout008 - Appendix D - Engineer Design Report Engineering Report Ferguson Farm Office Building Bozeman Gallatin County, Montana April, 2026 Prepared By: Hyalite Engineers, PLLC 161 W Haley Spring Road Ste 101 Bozeman, MT 59718
ENGINEERING REPORT – FERGUSON FARM Table of Contents January 2026 Page ii Version 4/16/2025 Table of Contents Table of Contents ........................................................................................................................ ii List of Tables .............................................................................................................................. ii List of Figures ............................................................................................................................ iii List of Appendices ...................................................................................................................... iii 1 Introduction ......................................................................................................................... 4 1.1 Purpose of Report ...................................................................................................... 4 1.2 Scope ......................................................................................................................... 4 2 Location and Site Information ............................................................................................. 4 3 Land Use ............................................................................................................................ 5 3.1 Existing ....................................................................................................................... 5 3.2 Proposed .................................................................................................................... 5 4 Potable Water Improvements .............................................................................................. 5 4.1 Building Water Use ..................................................................................................... 5 Irrigation Demand ............................................................................................................... 7 5 Sanitary Sewer Improvements ............................................................................................ 8 5.1 Proposed Improvements ............................................................................................. 8 6 Storm Water Improvements ................................................................................................ 9 6.1 Existing Conditions ..................................................................................................... 9 6.2 General Design ........................................................................................................... 9 6.3 Hydrologic Methodology ............................................................................................. 9 6.4 Basin A Retention Pond .............................................................................................11 6.5 Basin B Dry Well ........................................................................................................11 6.6 Basin C Retention Pond ............................................................................................11 6.7 Inlets & Storm Sewer .................................................................................................11 6.8 Groundwater ..............................................................................................................11 6.9 System Maintenance .................................................................................................12 6.10 Erosion Sediment Control ..........................................................................................12 6.11 Flooding.....................................................................................................................12 List of Tables Table 1 - Fixture Table ……………..……………………………………………………………………6 Table 2 - Runoff coefficients used. ............................................................................................10
ENGINEERING REPORT – FERGUSON FARM List of Figures January 2026 Page iii Version 4/16/2025 List of Figures Figure 1 - Vicinity map. .............................................................................................................. 4 List of Appendices A) Existing Plats & Approved Stormwater Plans B) Caddis Engineering Design Report C) Post-development Drainage Basins D) Pond Calculation & Summary
ENGINEERING REPORT – FERGUSON FARM Introduction January 2026 Page 4 Version 4/16/2025 1 Introduction 1.1 Purpose of Report This report is intended to serve as the design document for site/civil improvements associated with the construction of a new commercial building just west of the intersection of Huffine Lane and Boardwalk Avenue, in Bozeman, MT. 1.2 Scope Sanitary sewer service, fire and potable water service, and stormwater improvements are within the scope of this report. All improvements analyzed in this report are within the property. No off-site improvements are expected. 2 Location and Site Information The property occupies 1.10 acres and is located within City of Bozeman limits, in the SW ¼ of Section 10, Township 2S, Range 5E, P.M.M., Gallatin County, MT. The existing zoning of the site is B-2. The surrounding lots are B-2 as well. The property is within the service area for municipal water and sewer from the City of Bozeman. Figure 1 - Vicinity map.
ENGINEERING REPORT – FERGUSON FARM Land Use January 2026 Page 5 Version 4/16/2025 3 Land Use 3.1 Existing The subject property contains an existing parking lot section on the north side of the lot, but is vacant along the southern boundary. An 8-inch City of Bozeman water main exists along Boardwalk Ave. The main was installed in 2014 and City of Bozeman GIS information does not make any note of deficiencies in the area. The existing main extends west from Boardwalk Ave into the subject lot. Two stubs exist within the lot for water and fire service lines to connect with the main. An 8-inch diameter City of Bozeman sewer main exists along Boardwalk Ave and again extends west into the subject lot. The existing 8-inch main is PVC and laid at 0.83% slope, and flows via gravity to the north. All storm water has been accounted for during the initial development of the Spring Creek Village Resort Subdivision and Ferguson Farm Subdivision (Plat No. J-563). Existing infrastructure has been designed in accordance with City of Bozeman design standards. All applicable information has been attached with this submittal, please see Appendix A. 3.2 Proposed The proposed develop will consist of one, two story commercial building. The total square footage of the proposed building is 14,500 SF. As stated above, water and sewer infrastructure exists on-site and is properly sized to handle the demand from the proposed building. A 2-inch water service line, and a 4-inch fire service line will connect to existing city infrastructure on the property. Additionally, a 6-inch sanitary sewer line will service the proposed building, and will again connect with existing city infrastructure on the property. 4 Potable Water Improvements 4.1 Building Water Use Domestic Service Sizing 1 commercial building with 90 employees = 90 employees at 13 gpd (per DEQ 4) = 1170 gpd Maximum Day Flow Peaking factor = 2.3 (per City of Bozeman Design Standards) 1170 gpd (2.3) = 2691 gpd Max day flow = 2691 gpd / 1440 = 1.87 gpm
ENGINEERING REPORT – FERGUSON FARM Potable Water Improvements January 2026 Page 6 Version 4/16/2025 Peak Hour Demand Peaking factor = 3.0 (per City of Bozeman Design Standards) 1170 gpd (3.0) = 3510 gpd Peak hour flow = 3510 gpd / 1440 = 2.44 gpm The building will consist of multiple fixtures that are illustrated in the table below. As a check to the above flow, the number of fixture units were estimated as outlined in Table 1 below: Table 1 – Fixture Table Appliance Fixture Units X # Fixtures = Total Shower (per head) 2 0 = 0 Hose Bidd 2.5 0 = 0 Additional Hose Bibb 1 0 = 0 Service / Mop Basin 3 12 = 36 Lavatory Sink 1.0 6 = 6 Kitchen Sink 1.5 2 = 3 Water Closet 2.5 2 = 5 Total = 50 Based on the above fixture units (2021 Uniform Plumbing Code - Chart A 103.1(1)), the peak design flow is estimated around 55 gpm. The proposed 2” copper pipe is capable of flowing 55 gpm at approximately 5.73 ft/s.
ENGINEERING REPORT – FERGUSON FARM Potable Water Improvements January 2026 Page 7 Version 4/16/2025 As part of Caddis Engineering’s “Sewer, Water, & Stormwater Design Report” for the original Ferguson Farms 2 P.U.D Subdivision, they showed that the City of Bozeman’s fire hydrant number 1751 (at the corner of Resort Drive and Fallon Street) was tested. The report indicates, “there is an available static pressure of 128-psi at average daily demand and a residual pressure of 94-psi while flowing 1,625-gpm.” Please see Appendix B for Caddis Engineering Report. Irrigation Demand The DNRC provides an acre-foot usage of water for landscape/lawn area of 2.5 AF/acre. This translates to approximately 1” per week of irrigation usage. The proposed irrigation use for this site will be provided by the City of Bozeman. Below is the estimate flow rate for the project based on the total landscape square footage. Assumed 1”/week for irrigation of turf areas and 4-month irrigation season. Total irrigated turf/landscaped areas = 7,880 sqft = 0.06 acres 1”/week (16 weeks) = 1.33 ft of irrigation over 0.06 acres Total irrigation = 0.08 acre-feet/year = 3,485 cu.ft. ( 7.48 gal/cu.ft.) = 26,068 gal./year Over 120-day irrigation season, 15 hours of irrigation per day 26,068 gals./year (1 year/120 days) ( 1 day/15 hrs) (1hr/60 min) = 0.24 gpm In conclusion based on the above fixture units (2021 Uniform Plumbing Code - Chart A 103.1(1)), the peak design flow is estimated around 55 gpm and the irrigation demand peak design flow is estimated around 0.24 gpm for a total of 55.24 gpm. The proposed 2” copper pipe is capable of flowing 55.24 gpm at approximately 5.64 ft/s.
ENGINEERING REPORT – FERGUSON FARM Sanitary Sewer Improvements January 2026 Page 8 Version 4/16/2025 5 Sanitary Sewer Improvements 5.1 Proposed Improvements Per Lot 4, Spring Creek Village Resort, a 6” sanitary sewer service line exists on site. The proposed development will use City of Bozeman services, and will connect to the existing city service line. Length = Approximately 20 feet Slope = 2% Nominal Diameter = 6-inch Minimum Depth = 5 Maximum Depth = 7 feet Pipe Material = SDR 26 PVC (0.013 Roughness Coeff.) As proposed, the 6” service has a hydraulic capacity of 55 GPM, flowing at only 1.4” (23.3% full). This can be compared to the instantaneous building water demand of 55 GPM. For the purposes of estimating downstream system impact, from Section 4.1, the average day sewer flow is estimated to be 1170 gallons per day. The peak hour flow can be estimated using a peaking factor approach where; Peak Hour Flow = Average Day Flow × Peaking Factor, Peaking Factor = (18 + √P)/(4 + √P). where P denotes population in thousands (“Circular DEQ-2 Design Standards for Public Sewage Systems” 2016). The expected total population of the site is 90 employees, yielding a peaking factor of 4.26 and a peak hour flow of 207.7 gallons per hour (3.46 gpm).
ENGINEERING REPORT – FERGUSON FARM Storm Water Improvements January 2026 Page 9 Version 4/16/2025 6 Storm Water Improvements This section provides a design basis and hydraulic calculations for sizing stormwater facilities for Ferguson Farm Subdivision Lot 2, Block 2 commercial site. Per previously approved design reports (Lot 4, Spring Creek Village Resort and Ferguson Farm Subdivision, Block 2), all infrastructure has been sized for the 10-year, 2-hour storm event while all storm piping has been sized for the 25-year storm. 6.1 Existing Conditions The subject parcel is contained within Ferguson Farm Subdivision, an existing commercial development bordered by Boardwalk Avenue on the east, Valley Commons Drive on the north, and Huffine Lane to the south. The Subdivision was approved and constructed in 2017-2018. Drainage calculation for the subdivision was provided by the Master Site Plan for Spring Creek Village Resort Subdivision and Ferguson Farm Subdivision. The total area of the subject lot is 1.1 acres. Existing conditions consist of an asphalt parking area, sloping the north 3-5%. Storm water is conveyed via surface runoff through gutters to stormwater inlets, discharging into retention ponds. All storm water infrastructure was designed to hold a 10-year 2-hour storm event, within Block 2, Ferguson Farm Subdivision calculations performed by C&H Engineering. All applicable data and calculations of previously approved developments (Block 2, Ferguson Farm Subdivision, and Spring Creek Village Resort Subdivision) have been attached with this submission (see Appendix X). 6.2 General Design The proposed development will be a 14,500-SF structure connecting to the existing infrastructure. All existing storm water management has been sized according to City of Bozeman design standards, and are sized to handle to 10-year, 2-hour event (C&H Engineering, Ferguson Farm Subdivision, Block 2). In order to accommodate for the proposed, develop, design calculations were performed to ensure proper sizing throughout the system. All applicable design calculations can be found in Appendix C. 6.3 Hydrologic Methodology The rational method was used to determine peak runoff rates. The rational formula provides a peak runoff rate which occurs at the time of concentration. Q = CfCiA Where C = Weighted C Factor Cf = correction factor for infrequent storms i= Storm Intensity (in/hr) A = Area (acres) Q = Runoff (cfs)
ENGINEERING REPORT – FERGUSON FARM Storm Water Improvements January 2026 Page 10 Version 4/16/2025 The storm intensities were developed from table 6.5.2 of the City of Bozeman Design Standards and Specifications. Runoff coefficients for each basin were calculated using a weighted percentile of impervious and pervious area. The coefficient used are shown in the table below. Table 1 - Runoff coefficients used. RUNOFF COEFFICIENTS Asphaltic and Concrete 0.95 Heavy Soil (flat) 0.17 Heavy Soil (average) 0.22 Drives, Walks and Roofs 0.95 Time of concentration was determined using the following equation: Tt =
ENGINEERING REPORT – FERGUSON FARM Storm Water Improvements January 2026 Page 11 Version 4/16/2025 6.4 Basin A Retention Pond For the proposed development, Basin A is the combination of drainage basins 2 and 3 per C&H Engineering Storm Water Design Report (0.53 acres). The existing retention pond is located just west of the existing parking lot. Existing drainage inlets and 10” PVC drainage pipes convey runoff from the parking lot to a retention pond located just west of the parking lot. All existing conditions will remain, with the addition of a sidewalk area around the parking stalls, and patio/sidewalk around the building. The existing pond is oversized for the required runoff (3,093 CF provided for 1,130 CF required), and will be modified accordingly. With additional impervious area, the required storage needed for Basin A is 1,277 CF. A retention pond of 1,300 CF is proposed to hold the runoff produced by the design storm event. The proposed pond will be 1.5 feet deep, and maintain a side slope of 4:1, in accordance with City of Bozeman design standards. A swale will run along the western edge of the property to retention pond A to ensure there is no runoff from the site. In the event of a larger storm beyond the proposed ponds capacity, the pond will overtop and flow to the north into retention pond #2, per C&H Engineering Stormwater Design Report, Block 2. 6.5 Basin B Dry Well An existing dry well sized for the runoff from a two story 14,500 SF building will be utilized to capture the run off from the proposed development. The building is 14,500 SF. The dry well is located within the parking lot hardscape just north of the existing curb line. A 12” storm drainage pipe will be utilized to convey runoff from the roof drains to the dry well. Per C&H Engineering Report, Spring Creek Village Resort Lot 4, the drywell was sized purely for roof drainage area. Therefore, only runoff produced from the roof area will be stored in the dry well. 6.6 Basin C Retention Pond An existing storm pond is located in the southwest corner of the lot. The existing pond is 1.5 feet deep. With the proposed development, the required storage volume from Basin C is 228 CF. This existing pond will be expanded to add 326 CF of storage to account for the additional volume from Basin C. Therefore, adequate storage is provided for the additional volume of storm water runoff from the proposed development. 6.7 Inlets & Storm Sewer All existing inlets and storm sewer will remain in place. All infrastructure has been adequately sized for the proposed development. Surface runoff is conveyed to two storm inlets. The runoff is then piped via a 10” PVC pipe to Retention Pond A. The PVC pipe has been adequality sized for the 25-year outflow rate. 6.8 Groundwater Groundwater is known to be high in this location. During the original design process of the Ferguson Farm Subdivison, the ground water is estimated to be around 4,828.80 (10-13 feet deep throughout the site) at the highwater mark. With this elevation, it can be assumed that no stormwater structure will be inundated by the high groundwater mark.
ENGINEERING REPORT – FERGUSON FARM Storm Water Improvements January 2026 Page 12 Version 4/16/2025 6.9 System Maintenance Regular maintenance of stormwater facilities is necessary for proper function of the drainage system. All stormwater maintenance will be the responsibility of the property owner’s association. Maintenance items include removing debris from inlet grates, cleaning and flushing pipes, cleaning manhole sumps, and establishing ground cover after construction. The infiltration facilities must be inspected after every storm event to ensure that they are draining properly. The infiltration facilities will be cleaned and maintained by access risers installed on the underground stormwater retention system per “Contech Inspection and Maintenance Guide”. 6.10 Erosion Sediment Control During construction, stormwater pollutant controls will include silt fencing, straw wattles, rock check dams, and straw bales. Silt fence, straw waddles, or other perimeter protection will be installed on the down gradient edge of disturbed soil. Straw wattles, straw bales, or other erosion protection will be placed in existing inlets on-site. Temporary erosion control measures will be installed and continuously maintained for the duration of construction. 6.11 Flooding Excessive runoff from a large storm event (significantly exceeding the design storm, i.e 100-year) will be routed such that it does not inundate buildings, drainfields or over top the roadway. Per C&H Engineering report, “In the case of a storm exceeding the design storm, runoff will overflow the pond banks and flow north onto Fallon Street.” Therefore, in the event of a 100-year storm the retention systems will be filled causing the water to over top the curb and be routed to the existing oversized storm pond located in lot northwest corner of the Spring Creek Village Resort Subdivision.
APPENDIX A
SURVEY REQUESTED BY OWNER TO
CREATE 18 LOTS AND 2 OPEN SPACE
PARCELS FROM 1 EXISTING LOT WITHIN
A PLATTED SUBDIVISION.
OWNER: Boardwalk Properties, Inc.
DEED REF: Doc. No. 2482970
LEG EN D
R) RECORD DISTANCE OR AZIMUTH
M) MEASURED DISTANCE OR AZIMUTH
FOUND 5/8" REBAR WITH 1 1/4" PLASTIC CAP
MARKED (C&H ENGR #9518ES) OR AS NOTED.
0
SET 5/8" REBAR WITH 1 1/4" PLASTIC
CAP MARKED (C&H ENGR #9518ES)
LOT BOUNDARY
SURROUNDING PROPERTY LINE
EASEMENT LINE
SHARED PARKING, DRAINAGE, & ACCESS EASEMENT
BASIS FOR AZIMUTHS FROM NORTH:
MINOR SUBDIVISION NO. 295A, WITH THE EAST LINE OF THE SW
1/4 OF SEC 10, T2S, R5E, BEING 180-31'24"
N45'00'00"E] BEARING COMPUTED FROM
AZIMUTHI SHOWN LOT 2
Minor Subd. No. 340
TBP Condominium
60 I 60
L
0
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LOT 3
Minor Subd. No. 340
Theah, LLC
2177580
LOT 4
Minor Subd. No. 340
AO Group, LLC
2217456
LOT 5A
Minor Subd. No. 340A
First Security Bank
2163387
FINAL PLAT OF J-563 THE
FERGUSON FARM SUBDIVISION BEING
AN AMENDED PLAT OF LOT 4, MINOR SUBDIVISION NO. 295A LOCATED /
N THE SW 1/4, SEC. 10, T. 2 S., R. 5 E. OF
P. M. M., GALLATIN COUNTY, MONTANA II
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SALE DEED TO STATE OF MONTANA, DEPT. O O 22' UTILITY EASEMENT t` I OF
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U.S. Highway
No. 191) Film 78, Page
1707 R/W a LOT L Minor
Subdivision 313
Frank R. Kountz,
Etal. 1414.07 269'
54'29"
Fd. 2j" Alum.
Cap MDOH)
TRACT 1
COS
2229 Richard
F Kountz
Kristie Kountz 2514922
Page: 1
of
3 06/19/2015 11:18:47 AM Fee: $20.50 Charlotte Mills - Gallatin
County, MT PLAT 11111111111111111 11111111111I1IIIIII1IIIIIIIIIIIIIIIIIII11I11111111I11111 Sheet
1 of 3
FINAL PLAT OF J-563
7 GUSEtWER 1J lit f SL E 11 A ,1115 11 V
BEING AN AMENDED PLAT OF LOT 4, MINOR SUBDIVISION NO. 295A
SURVEY BY OWNER TO
CREATE 18 (LOTS ADND2 OPEN SPACE L 0CA TED IN THE SW 114.9 SEC. 10.9 T. 2 S., R. 5 E. PARCELS
FROM 1 EXISTING LOT WITHIN A
PLATTED SUBDIVISION. OF P.M.M., GALLATIN COUNTY, MONTANA OWNER:
Boardwalk Properties, Inc. DEED
REF: Doc. No. 2482970 CERTIFICATE OF DEDICATION We,
the undersigned property owners, do hereby certify that we have caused to be surveyed, subdivided and platted into lots,
parcels, blocks, roads and alleys and other divisions and dedications, as shown by this plat hereunto included, the following
described tract of land, to wit: To
u
LEGAL
DESCRIPTION Lot
4, Minor Subdivision No. 295A, according to the plat thereof, on file and of record in the office of the Clerk and Recorder,
Gallatin County, Montana, located in the Southwest Quarter of Section 10, Township 2 South, Range 5 East of P.
M.M., City of Bozeman, Gallatin County, Montana. Area =
869,528 square feet, 19.9616 acres or 80,781.8 square meters. Subject to existing easements. The
above described tract of land is to be known and designated as THE FERGUSON FARM SUBDIVISION, City of Bozeman,
Gallatin County, Montana; and the lands included in all streets, avenues, alleys and parks or public lands shown
on said plat are hereby granted and donated to the City of Bozeman for the public use and enjoyment. Unless specifically
listed herein, the lands included in all streets, avenues, alleys, and parks or public lands dedicated to the public
are accepted for public use, but the city accepts no responsibility for maintaining the same. The owner agrees that
the City has no obligation to maintain the lands included in all streets, avenues, alleys, and parks or public lands hereby
dedicated to public use. The lands included in all streets, avenues, alleys, and parks or public lands dedicated to the
public for which the City accepts responsibility for maintenance include: NONE. The
undersigned hereby grants unto each and every person, firm or corporation, whether public or private, providing or offering
to provide telephone, electric power, gas, internet, cable television or other similar utility or service, the right to the
joint use of an easement for the construction, maintenance, repair and removal of their lines and other facilities, in, over,
under and across each area designated on this plat as 'Utility Easement' to have and to hold forever. Dated
this U-- _ day of M 2015. STATE
OF MONTANA COUNTY
OF GALLATIN Boardwalk
Properties, Inc., a Montana Corporation By:
V%-AA N&_ Michael
W. Delanev. President By.
Ilea
o Indreland, Vice Presidentl This
instrument was signed or acknowledged before me on this day of 2015, by Michael W. Delaney
as President and Ileana Indreland as Vice President of Board ertip- S Ali a Corporation. e ^
DQ SPA'O`; Notary Public NOTARIq4 ,
for the State of Montana Notary
Public State Mo ta 1 _ *: —A * = Residing
at: Printed
Name: N.SEA@.=Q Bozeman, Montana Residing
at:-9P. My Commission Expires: g — — ------------------- 10 FMOAugust 25,22018Mycommissionexpires: C2 S, 11ao l$ —-- -~--- - CONSENT
OF MORTGAGEE I,
the undersigned mortgagee or encumbrancer, do hereby join in and consent to the described plat, releasing my respective
liens, claims or encumbrances as to any portion of said lands now being platted into streets, avenues, parks or
other public areas which are dedicated to the City of Bozeman for the public use and enjoyment. , k%%_
Dated
this S ' day of lA` 2015. STATE
OF MONTANA COUNTY
OF GALLATIN First
Security Bank By. -
t it.L--j L `— Printed
Name: Its:
This
instrument was signed or acknowledged before me on this ,7_1 day of _ 2015, by _ as _EV_P_ iL_00 _________ of First Security Bank. ANDREA
SPAULDING Q
Residing at: %i1 -' ' PA O' Notary Public Notary
Public fe the State.df Montana=°NoTAR,q4for the State of Montana Residing at:
L5'. SEAR,
Q? Bozeman, Montana Printed Name:
YLQ tJ l_ My commission expires: iQ[ J =,9p . , - .^'PMy Commission Expires: at 25,
2018 CERTIFICATE OF
SURVEYOR I, Mark
A. Chandler, Professional Engineer and Land Surveyor No. 9518ES, do hereby certify that between Oct. 1, 2012 and April
ZD , 2015, The Ferguson Farm Subdivision was surveyed under my direct supervision and that I have platted the same
as shown on the accompanying plat and as described, in accordance with the provisions of the Montano Subdivision and
Platting Act, Sections 76-3-101 through 76-3-625 M.C.A., and the Bozeman Municipal Code. Dated this
TM_ day of _,d& ____, 2015. Montana Registration
No. 9518ES CERTIFICATE OF
COMPLETION OF IMPROVEMENTS We, Michael
W. Delaney and Ileana Indreland, and I, Mark A. Chandler, a registered professional engineer licensed to practice in
the State of Montana, hereby certify that the following improvements, required to meet the requirements of this title or
as a condition(s) of approval of The Ferguson Farm Subdivision, have been installed: water mains and services, sanitary sewer
mains and services, storm sewer improvements, and street improvements. Financially Guaranteed
Improvements: landscaping and irrigation of public right-of-way and approximately 500 square feet of
sidewalk where private utilities will be installed. The subdivider hereby warrants against defects in these improvements for
a period of two years from the date , of acceptance by the City of Bozeman. The subdivider grants possession of
all public infrastructure improvements to the City of Bozeman, and the City hereby accepts possession of all public infrastructure
improvements, subject to the above indicated warranty. Dated this
S'TK day of RA Y , 2015. Michael W.
Delaney, President, Boardwalk Properties, Inc. Director bf
Public Works, City of Bozeman, Montana Montana Registration
No. 9518ES Ileana Indreland,
Vice President, Boardwalk Properties, Inc. CERTIFICATE OF
DIRECTOR OF PUBLIC WORKS I, Director
of Public Works, City of Bozeman, Montana, do hereby certify that the accompanying Plat has been duly examined and
has found the same to conform to the law, approves it, and hereby accepts the dedication to the City of Bozeman for
the public use of any and all lands shown on the plat as being dedicated to such use. Dated this
day of nt , 2015!_7 / Director 6f
Public Works, City of Bozeman, Montana CERTIFICATE OF
EXCLUSION FROM MONTANA DEPARTMENT OF ENVIRONMENTAL
QUALITY REVIEW This Plat,
located in Gallatin County, Montana, is within the City of Bozeman, Montana, a first-class municipality, and within the
planning area of the Bozeman growth policy which was adopted pursuant to Section 76-1-601 et seq., M.C.A., and can
be provided with adequate storm water drainage and adequate municipal facilities. Therefore, under the provisions of
Section 76-4-125(2)(d) M.C.A., this subdivision is excluded from the requirement for Montana Department of Environmental
Quality review. r_ _ i`
Dated this day of 2015. Director of
Public Works, City of Bozeman, Montana VOW CERTIFICATEOF
COUNTY TREASURER I, Kimberly
Buchanan, Treasurer of Gallatin County, Montana, do hereby certify that the accompanying Plat has been duly examined and
that all real property taxes and special assessments as ssed and levied on the land t be divided have been paid.
P 5S zr ° " j"
1*4 (
o By Deputy
Treasurer
of Gallatin C y CLERK AND
RECORDER OF MONTq
o MARK
A. o CHANDLERrn No.
9518ES
o29 F
FG
1
S i Q O NG/!
VEER
P/ OF MONTgNq\
o MARK
A. - n CHANDLER
No. 9518ES
D 9
F
FG
1
SiE`'Q O G/
INFER
pN I, Charlotte
Mills, Clerk and Recorder of Gallatin County, Montana, do hereby certify that the foregoing instrument was filed in
my office at .tLr o'clock A =. .M. this K day of ______- A.D., 2015, and recorded in Book of Plats,
on Page __, records of the Clerk and Recorder, Gallatin County, Montana. \,,,C p
51 tf 9• 440By: =4'
2n Deputy Jerk
and Recorder CONSENT OF
MORTGAGEE I, the
undersigned mortgagee or encumbrancer, do hereby join in and consent to the described plat, releasing my respective liens,
claims or encumbrances as to any portion of said lands now being platted into streets, avenues, parks or other
public areas which are dedicated to the City of Bozeman for the public use and enjoyment. lJJ Dated
this
day of 2015. Springcreek Village,
LLC. By. Michael
W. Delaney, member i A
u STATE OF
MONTANA _ y Ileana Indreland, member COUNTY OF
GALLATIN This instrument
was signed or acknowledged before me on this _ 2015, by Michael W. Delaney and
Ileana Indreland as members of Springcreek Village, LLC.,. .a M,Qnt PtiLL iPM Company. Notary Public
I (3, +,, _
G) for the State of Montana 0^1° _ _ _____________
I Residing at: Notary Public
f the fS,ate.bf Montano :_ Bozeman, Montana Printed Name: __
r, .` My Commission Expires: Residing at:_ --------------
my ueusr2s,
2018
commission eP
lres: 2514922Page:
2
of 3 06/19/2015 11:18:47 AM Fee: $20.50 Charlotte Mills - Gallatin County, MT PLAT 1111111I111111III111111111 IN
11111111111111111111111111111111111111111111111111111111111111111111 Sheet 2 of311019
FINAL PLA T OF
THE FERGUSON FARM SUBDIVISION
BEING AN AMENDED PLAT OF LOT 4, MINOR SUBDIVISION NO. 295A
L 0 CA TED IN THE S W 1 /4, SEC. 10.9 T. 2 S. , R. 5 E.
OF P.M.M., GALLATIN COUNTY, MONTANA
SURVEY REQUESTED BY OWNER TO
CREATE 18 LOTS AND 2 OPEN SPACE
PARCELS FROM 1 EXISTING LOT WITHIN
A PLATTED SUBDIVISION.
OWNER: Boardwalk Properties, Inc.
DEED REF: Doc. No. 2482970
CONDITIONS OF APPROVAL FOR THE FERGUSON FARM SUBDIVISION,
LOCATED IN THE SW 1 /4, SEC. 10, T 2 S., R 5 E. OF P.M.M.
CITY OF BOZEMAN, GALLATIN COUNTY, MONTANA
I hereby certify that the approval of the application for The Ferguson Farm Subdivision did not contain any Conditions of Approval that would
affect the text or graphics contained on this plat other than as shown hereon. I hereby certify that all conditions of subdivision application have
been satisfied and the information shown is current as of the date of this certification and that changes to any land use restrictions or
encumbrances may be made by amendments to covenants, zoning regulations, easements, or other documents as allowed by law or by local
regulations.
I
CERTIFICATE OF TRANSFER OF OWNERSHIP Bc
COMPLETION OF NON—PUBLIC IMPROVEMENTS
The following are hereby granted and donated to the property owners association noted below for their use and enjoyment: Private Common Open Space #1 and
Private Common Open Space #2. Unless specifically listed in the Certificate of Dedication, the city accepts no responsibility for maintaining the same. We, the
undersigned property owners, hereby further certify that the following non—public improvements, required to meet the requirements of Chapter 38 of the Bozeman
Municipal Code, or as a condition(s) of approval of the subdivision plotted herewith, have been installed in conformance with any approved plans and
specifications prepared in accordance with the standards of Chapter 38 or other City design standards, or have been financially guaranteed and are covered by
the subdivision improvements agreement accompanying and recorded with this plat.
Installed Improvements: Stormwater improvements.
Financially Guaranteed Improvements: Open Space landscaping and irrigation.
The subdivider hereby grants ownership of all non—public infrastructure improvements to the Ferguson Farm Property Owners Association.
Dated this 4,'__ day of _B_!_, 2015.
STATE OF MONTANA
COUNTY OF GALLATIN
Boardwalk Properties, Inc., o Montano Corporation
N By.
Michael W. Delaney, President
By:
Ileana Indreland, Vice President
This instrument was signed or acknowledged before me on this jth day of_____, 2015, by Michael W.
Delaney as President and Ileana Indreland as Vice President of Boardwalk Properties, I49, a Montana Corporation.
Notary Public `fg{,,thhe,, St
Printed Name: .l3.Ll L .
Residing at: _
My commission e ires:
tana
SPAS . ANDREA SPAULDiNG
Q• •.Zo ; Notary Public
Q'NpTAR,A c= for the State of MontanaResidingat:
SIEAt.Q;= Bozeman, Montana
of rno?P My commission Explros:
Aurlust 25, 2010
F. i0= &I 0C •
AREA OF LOTS 673,868 SQ FT 15.4699 ACRES
OPEN SPACE/COMMON AREA 35,756 SQ FT 0.8209 ACRES
AREA OF PUBLIC STREETS = 159,904 SQ FT 3.6709 ACRES
TOTAL AREA = 869,528 SQ FT 19.9616 ACRES
GENERAL NOTES
1. IF A UTILITY EASEMENT IS WIDER OR GREATER IN WIDTH THAN THE
BUILDING SETBACK REQUIRED BY THE CITY OF BOZEMAN MUNICIPAL
CODE, SAID EASEMENT SHALL APPLY WITH RESPECT TO THE
PLACEMENT OF BUILDING ON A LOT.
2. THE FOLLOWING STREETS WITHIN PUBLIC RIGHT—OF—WAYS OF THE
SUBDIVISION SHALL BE PRIVATELY MAINTAINED IN PERPETUITY:
BOARDWALK AVENUE, FIELD STREET, VALLEY COMMONS DRIVE.
3. STORMWATER FACILITIES, INCLUDING DRAINAGE DITCHES, ARE TO BE
MAINTAINED BY THE PROPERTY OWNERS ASSOCITATION.
4. A ONE FOOT WIDE NO ACCESS STRIP IS PROVIDED ALONG THE
SOUTHERN BORDER OF THE SUBDIVISION PROHIBITING VEHICLE
ACCESS TO HUFFINE LANE.
5. UPON THE THIRD ANNIVERSARY OF THE PLAT RECORDATION OF ANY
PHASE OF THIS SUBDIVISION, ANY LOT OWNER WHO HAS NOT
CONSTRUCTED THEIR RESPECTIVE SIDEWALK SHALL, WITHOUT FURTHER
NOTICE, CONSTRUCT WITHIN 30 DAYS, SAID SIDEWALK FOR THEIR
LOT(S), REGARDLESS OF WHETHER OTHER IMPROVEMENTS HAVE BEEN
MADE UPON THE LOT.
6. WATER RIGHTS, OR CASH —IN —LIEU OF WATER RIGHTS, HAVE NOT
BEEN PROVIDED WITH THIS SUBDIVISION AND WILL BE REQUIRED
DURING THE SITE PLAN REVIEW PROCESS FOR ANY FUTURE
DEVELOPMENT.
Sheet 3 of 3
2514922
Page: 3 of 3 06/19/2015 11:18:47 AM Fee: $20.50
Charlotte Hills - Gallatin County, MT PLAT
11111111111111111 1II11111 1111111IIIIIIIIIII 1111111111111111111111111111111111111111111IN
11019
DESIGN REPORT
STORMWATER MANAGEMENT
FERGUSON FARM SUBDIVSION
BLOCK 2
Prepared for:
Delaney & Company, Inc.
101 E. Main Street D, Bozeman, MT 59705
Prepared by:
C&H Engineering and Surveying, Inc.
1091 Stoneridge Drive, Bozeman, MT 59718
(406)587-1115
Project Number: 170520
October 2017
INTRODUCTION
Block 2 of The Ferguson Farm Subdivision is an existing commercial development bordered by
Boardwalk Avenue on the east, Valley Commons Drive on the north, a commercial lot to the west,
and Huffine Lane to the south. It was approved and constructed in 2017-2018. Drainage
calculations for the entire subdivision were provided during the Master Site Plan review process.
This report summarizes the drainage within Block 2 with a total area of 3.55 acres. Stormwater
runoff is conveyed via surface flow and gutters to internal retention ponds. A drainage area map
is included in Appendix A. Calculations for each individual drainage area are included in Appendix
B.Please note the roof drainage from the two future buildings at the south side of Block 2 (Lots 2
and 3) each have a drywell connected, and are not included in this updated analysis.
STORM SEWER FACILITIES DESIGN
Storm sewer facilities were sized for the 25-yr storm using Manning’s Equation. For each inlet,
the contributing area, weighted C factor, and time to concentration were calculated (see Appendix
B). These values were input into Manning’s Equation to check capacity and flow characteristics
for inlets and storm drain pipes. The Storm Sewer Summary Report is included in Appendix C.
RETENTION POND DESIGN
Ponds have been sized according to City of Bozeman Design Standards. Retention ponds are sized
to capture the entire volume of the 10-year, 2-hour storm event. Pond sizing calculations can be
found in Appendix D.
Retention Pond #1 (No change from original design)
Retention Pond #1 is located just west of the existing parking lot. It receives runoff from Drainage
Areas 2 and 3, totaling 0.52 acres. Runoff from Drainage Area 2 is captured in the existing storm
inlet 1, located on the south side of the middle island curb in the west half of the existing parking
lot. From this point, the runoff flows into a 10” PVC pipe that conveys runoff to storm
inlet/manhole combo 2, located along the west curb of the existing parking lot. Runoff from
Drainage Area 3 also is captured in the existing storm inlet/manhole combo 2. From this point, the
runoff flows into a 15” PVC pipe that conveys the runoff to the existing retention pond #1. The
required pond volume was calculated to be 1,130 cubic feet. The existing pond is designed to store
3,093 cubic feet of stormwater. In the case of larger storms beyond the pond’s capacity to capture
and infiltrate, the pond will overtop and flow north into the proposed retention pond #2. Supporting
calculations for the required pond volume can be found in Appendix D.
Retention Pond #2
Retention Pond #2 is located just west of the existing parking lot and just north of the existing
retention pond #1. It receives runoff from Drainage Area 4 (originally part of Drainage Area #9,
see Appendix E), totaling 0.50 acres. Runoff from Drainage Area 4 is conveyed via surface flow
and gutters to an existing curb cut and drainage swale located to the north of the existing pond.
From this point, the runoff flows into the drainage swale into the existing retention pond #2. The
required pond volume was calculated to be 1,336 cubic feet. The existing pond was designed to
store 1,500 cubic feet of stormwater. In the case of larger storms beyond the pond’s capacity to
capture and infiltrate, the pond will overtop and flow north into the landscape area. Supporting
calculations for the required pond volume can be found in Appendix D.
Subdivision Storm System
Drainage Area #1 (Drainage Area #6 and part of Drainage Area #9 in original stormwater design
report for Lot 4, Spring Creek Village Resort Subdivision; see Appendix E) consists of the east
half of the existing Block 2 parking lot and the north half of the northwestern drive aisle, totaling
1.10 acres. Runoff from Drainage Area 1 flows to the existing stormwater infrastructure
in Boardwalk Avenue, which ultimately discharges to the existing Retention Pond 1A.
Retention Pond 1A is located in the northwest corner of the subdivision and receives runoff from
the existing Boardwalk Avenue, Valley Commons Drive, and Field Street. The pond is
sized to receive drainage from these streets as well as runoff from the parking lots in Blocks 1,
2, 3, 4, and 5. The original master drainage plan allocated 2,840 cubic feet of runoff volume for
Block 2 (Drainage Area #6. Drainage Area #9 originally went to proposed retention pond
2). The proposed contribution from Block 2 (Drainage Area #1) is now 2,701 cubic feet;
therefore, Retention Pond 1A will have adequate capacity. In the case of a storm exceeding the
design storm, runoff will overflow the pond banks and flow north onto Fallon Street. See
Appendix D for supporting calculations that the existing stormwater infrastructure can
accommodate this runoff.
APPENDIX A
DRAINAGE AREA MAP
BLOC
K
2
APPROX. EXTENT OFUTILITY EASMENT LINE PERCIVIL DRAWINGS
APPENDIX B
DRAINAGE AREA CALULATIONS
DRAINAGE AREA #1
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2)C * Area
ROW Hardscape 0.95 41211 39151
ROW Landscape 0.2 7493 1499
OS/Park 0.2 0 0
Low-Med Residential 0.35 0 0
Dense Residential 0.5 0 0
Commercial Neighborhood 0.6 0 0
Commercial Downtown 0.8 0 0
Industrial 0.8 0 0
Total 48704 40649
A = Area (acres)1.12
C = Weighted C Factor 0.83
2. Calculate Tc (Time to Concentration)
Tc Overland Flow
Tc = 1.87 (1.1-CCf)D1/2/S1/3
Storm
S = Slope of Basin (%) 2.36 Return (yrs)Cf
C = Rational Method Runoff Coefficient 0.95 2 to 10 1
Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1
D = Length of Basin (ft) 332 26 to 50 1.2
51 to 100 1.25
Tc Overland Flow (minutes)2.56
Tc Gutter Flow
Tc = L/V/60
V = (1.486/n)R2/3 S1/2
n = Mannings Coefficient 0.013
R = Hydraulic Radius A/P (ft)0.13 (0.15' below top of curb)
S = slope (%)2.20%
L = length of gutter (ft)0
V = mean velocity (ft/s)4.45
Tc Gutter Flow (minutes) =0.00
Tc Total =2.56
3. Calculate Flow (Rational Formula)
Q = CIA
C = Weighted C Factor 0.83 (calculated above)
I = 0.78 Tc-0.64 (in/hr)5.87 (25-yr storm)
A = area (acres) 1.12 (calculated above)
Q = REQUIRED GUTTER CAPACITY (cfs) 5.48 (assuming no carry flow)
PROVIDED GUTTER CAPACITY
1. Calculate Gutter Capacity @ 0.15' Below Top of Curb
Q = (1.486/n)AR2/3 S1/2
n = Mannings Coefficient 0.013
A = Area (ft2)1.24 (0.15' below top of curb)
P = Wetted perimeter (ft)9.23 (0.15' below top of curb)
R = Hydraulic Radius A/P (ft)0.13 (0.15' below top of curb)
S = slope (%)2.36%
Q = PROVIDED GUTTER CAPACITY (cfs)5.51
DRAINAGE AREA #2
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2)C * Area
ROW Hardscape 0.95 8909 8464
ROW Landscape 0.2 884 177
OS/Park 0.2 0 0
Low-Med Residential 0.35 0 0
Dense Residential 0.5 0 0
Commercial Neighborhood 0.6 0 0
Commercial Downtown 0.8 0 0
Industrial 0.8 0 0
Total 9793 8640
A = Area (acres)0.22
C = Weighted C Factor 0.88
2. Calculate Tc (Time to Concentration)
Tc Overland Flow
Tc = 1.87 (1.1-CCf)D1/2/S1/3
Storm
S = Slope of Basin (%) 3.52 Return (yrs)Cf
C = Rational Method Runoff Coefficient 0.95 2 to 10 1
Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1
D = Length of Basin (ft) 145 26 to 50 1.2
51 to 100 1.25
Tc Overland Flow (minutes)1.48
Tc Gutter Flow
Tc = L/V/60
V = (1.486/n)R2/3 S1/2
n = Mannings Coefficient 0.013
R = Hydraulic Radius A/P (ft)0.13 (0.15' below top of curb)
S = slope (%)2.00%
L = length of gutter (ft)0
V = mean velocity (ft/s)4.24
Tc Gutter Flow (minutes) =0.00
Tc Total =1.48
3. Calculate Flow (Rational Formula)
Q = CIA
C = Weighted C Factor 0.88 (calculated above)
I = 0.78 Tc-0.64 (in/hr)8.34 (25-yr storm)
A = area (acres) 0.22 (calculated above)
Q = REQUIRED GUTTER CAPACITY (cfs) 1.65 (assuming no carry flow)
PROVIDED GUTTER CAPACITY
1. Calculate Gutter Capacity @ 0.15' Below Top of Curb
Q = (1.486/n)AR2/3 S1/2
n = Mannings Coefficient 0.013
A = Area (ft2)1.24 (0.15' below top of curb)
P = Wetted perimeter (ft) 9.23 (0.15' below top of curb)
R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb)
S = slope (%) 2.00%
Q = PROVIDED GUTTER CAPACITY (cfs) 5.26
DRAINAGE AREA #3
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2)C * Area
ROW Hardscape 0.95 7271 6907
ROW Landscape 0.2 5611 1122
OS/Park 0.2 0 0
Low-Med Residential 0.35 0 0
Dense Residential 0.5 0 0
Commercial Neighborhood 0.6 0 0
Commercial Downtown 0.8 0 0
Industrial 0.8 0 0
Total 12882 8030
A = Area (acres)0.30
C = Weighted C Factor 0.62
2. Calculate Tc (Time to Concentration)
Tc Overland Flow
Tc = 1.87 (1.1-CCf)D1/2/S1/3
Storm
S = Slope of Basin (%) 3.82 Return (yrs)Cf
C = Rational Method Runoff Coefficient 0.95 2 to 10 1
Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1
D = Length of Basin (ft) 142 26 to 50 1.2
51 to 100 1.25
Tc Overland Flow (minutes)1.43
Tc Gutter Flow
Tc = L/V/60
V = (1.486/n)R2/3 S1/2
n = Mannings Coefficient 0.013
R = Hydraulic Radius A/P (ft)0.13 (0.15' below top of curb)
S = slope (%)2.38%
L = length of gutter (ft)32
V = mean velocity (ft/s)4.62
Tc Gutter Flow (minutes) =0.12
Tc Total =1.54
3. Calculate Flow (Rational Formula)
Q = CIA
C = Weighted C Factor 0.62 (calculated above)
I = 0.78 Tc-0.64 (in/hr)8.12 (25-yr storm)
A = area (acres) 0.30 (calculated above)
Q = REQUIRED GUTTER CAPACITY (cfs) 1.50 (assuming no carry flow)
PROVIDED GUTTER CAPACITY
1. Calculate Gutter Capacity @ 0.15' Below Top of Curb
Q = (1.486/n)AR2/3 S1/2
n = Mannings Coefficient 0.013
A = Area (ft2)1.24 (0.15' below top of curb)
P = Wetted perimeter (ft) 9.23 (0.15' below top of curb)
R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb)
S = slope (%) 2.38%
Q = PROVIDED GUTTER CAPACITY (cfs) 5.73
DRAINAGE AREA #4
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2)C * Area
ROW Hardscape 0.95 18271 17358
ROW Landscape 0.2 3543 709
OS/Park 0.2 0 0
Low-Med Residential 0.35 0 0
Dense Residential 0.5 0 0
Commercial Neighborhood 0.6 0 0
Commercial Downtown 0.8 0 0
Industrial 0.8 0 0
Total 21814 18066
A = Area (acres)0.50
C = Weighted C Factor 0.83
2. Calculate Tc (Time to Concentration)
Tc Overland Flow
Tc = 1.87 (1.1-CCf)D1/2/S1/3
Storm
S = Slope of Basin (%) 2.44 Return (yrs)Cf
C = Rational Method Runoff Coefficient 0.95 2 to 10 1
Cf = Frequency Adjustment Factor 1.1 11 to 25 1.1
D = Length of Basin (ft) 229 26 to 50 1.2
51 to 100 1.25
Tc Overland Flow (minutes)2.10
Tc Gutter Flow
Tc = L/V/60
V = (1.486/n)R2/3 S1/2
n = Mannings Coefficient 0.013
R = Hydraulic Radius A/P (ft)0.13 (0.15' below top of curb)
S = slope (%)2.00%
L = length of gutter (ft)0
V = mean velocity (ft/s)4.24
Tc Gutter Flow (minutes) =0.00
Tc Total =2.10
3. Calculate Flow (Rational Formula)
Q = CIA
C = Weighted C Factor 0.83 (calculated above)
I = 0.78 Tc-0.64 (in/hr)6.66 (25-yr storm)
A = area (acres) 0.50 (calculated above)
Q = REQUIRED GUTTER CAPACITY (cfs) 2.76 (assuming no carry flow)
PROVIDED GUTTER CAPACITY
1. Calculate Gutter Capacity @ 0.15' Below Top of Curb
Q = (1.486/n)AR2/3 S1/2
n = Mannings Coefficient 0.013
A = Area (ft2)1.24 (0.15' below top of curb)
P = Wetted perimeter (ft) 9.23 (0.15' below top of curb)
R = Hydraulic Radius A/P (ft) 0.13 (0.15' below top of curb)
S = slope (%) 2.00%
Q = PROVIDED GUTTER CAPACITY (cfs) 5.26
APPENDIX C
STORM SEWER FACILITIES
CALCULATIONS
PIPE # 1 (ST Inlet 1 Outlet Pipe) 25-YR OUTFLOW RATE
REQUIRED CAPACITY
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2)C * Area
ROW Hardscape 0.95 8909 8464
ROW Landscape 0.2 884 177
OS/Park 0.2 0 0
Low-Med Residential 0.35 0 0
Dense Residential 0.5 0 0
Commercial Neighborhood 0.6 0 0
Commercial Downtown 0.8 0 0
Industrial 0.8 0 0
Total 9793 8640
A = Area (acres) 0.22
C = Weighted C Factor 0.88
2. Calculate Rainfall Intensity (Duration = Max Tc from Contributing Drainage Areas)
i = 0.78x-0.64 (25-yr Storm, Fig. I-3, COB Design Standards)
x = storm duration (hrs) 0.02 (DA #2)
i = rainfall intensity (in./hr.) 8.34
3. Calculate 25-yr Pond Outflow Rate
Q = CiA
C = Rational Method Runoff Coefficient 0.88 (calculated above)
i = rainfall intensity (in./hr.) 8.34 (calculated above)
A = Area (acres) 0.22 (calculated above)
Q = 25-yr Pipe Flow Rate (cfs) 1.65
MANNING'S EQUATION FOR PIPE FLOW (PROVIDED CAPACITY)
Pipe: 1 Location: ST Inlet 1 Outlet Pipe
INPUT
D= 10 inches
d= 9.38 inches
Mannings Formula n= 0.013 mannings
57.7 degrees
Q=(1.486/n)ARh2/3S1/2 S= 0.0085 slope in/in
R=A/P
A=cross sectional area
P=wetted perimeter V=(1.49/n)Rh2/3S1/2
S=slope of channel Q=V x A
n=Manning's roughness coefficient
Solution to Mannings Equation
Area,ft2 Wetted
Perimeter, ft
Hydraulic
Radius, ft velocity ft/s flow, cfs
PVC 0.013
0.53 2.20 0.24 4.09 2.17 PE (<9"dia) 0.015
PE (>12"dia) 0.02
PE(9-12"dia) 0.017
CMP 0.025
ADS N12 0.012
HCMP 0.023
Conc 0.013
Manning's n-values
d
D
PIPE # 2 (ST Inlet/MH Combo 2 Outlet Pipe) 25-YR OUTFLOW RATE
REQUIRED CAPACITY
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2)C * Area
ROW Hardscape 0.95 16180 15371
ROW Landscape 0.2 6495 1299
OS/Park 0.2 0 0
Low-Med Residential 0.35 0 0
Dense Residential 0.5 0 0
Commercial Neighborhood 0.6 0 0
Commercial Downtown 0.8 0 0
Industrial 0.8 0 0
Total 22675 16670
A = Area (acres) 0.52
C = Weighted C Factor 0.74
2. Calculate Rainfall Intensity (Duration = Max Tc from Contributing Drainage Areas)
i = 0.78x-0.64 (25-yr Storm, Fig. I-3, COB Design Standards)
x = storm duration (hrs) 0.03 (DA #3)
i = rainfall intensity (in./hr.) 8.12
3. Calculate 25-yr Pond Outflow Rate
Q = CiA
C = Rational Method Runoff Coefficient 0.74 (calculated above)
i = rainfall intensity (in./hr.) 8.12 (calculated above)
A = Area (acres) 0.52 (calculated above)
Q = 25-yr Pipe Flow Rate (cfs) 3.11
MANNING'S EQUATION FOR PIPE FLOW (PROVIDED CAPACITY)
Pipe: 2 Location: ST Inlet/MH Combo 2 Outlet Pipe
INPUT
D= 15 inches
d= 14.07 inches
Mannings Formula n= 0.013 mannings
57.7 degrees
Q=(1.486/n)ARh2/3S1/2 S= 0.0058 slope in/in
R=A/P
A=cross sectional area
P=wetted perimeter V=(1.49/n)Rh2/3S1/2
S=slope of channel Q=V x A
n=Manning's roughness coefficient
Solution to Mannings Equation
Area,ft2 Wetted
Perimeter, ft
Hydraulic
Radius, ft velocity ft/s flow, cfs
PVC 0.013
1.20 3.30 0.36 4.43 5.29 PE (<9"dia) 0.015
PE (>12"dia) 0.02
PE(9-12"dia) 0.017
CMP 0.025
ADS N12 0.012
HCMP 0.023
Conc 0.013
Manning's n-values
d
D
APPENDIX D
POND SIZING CALCULATIONS
RETENTION POND # 1
REQUIRED VOLUME
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2)C * Area
ROW Hardscape 0.95 16180 15371
ROW Landscape 0.2 6495 1299
OS/Park 0.2 0 0
Low-Med Residential 0.35 0 0
Dense Residential 0.5 0 0
Commercial Neighborhood 0.6 0 0
Commercial Downtown 0.8 0 0
Industrial 0.8 0 0
Total 22675 16670
C=Weighted C Factor 0.74
2. Calculate Required Volume
Q = CIA
V=7200Q
C = Weighted C Factor 0.74
I = intensity (in/hr) 0.41 (10 yr, 2hr storm)
A = Area (acres) 0.52
Q = runoff (cfs) 0.16
V = REQUIRED VOL (ft3)1130
PROVIDED VOLUME (ft3)3,093
RETENTION POND # 2
REQUIRED VOLUME
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2)C * Area
ROW Hardscape 0.95 18271 17358
ROW Landscape 0.2 3543 709
OS/Park 0.2 0 0
Low-Med Residential 0.35 0 0
Dense Residential 0.5 0 0
Commercial Neighborhood 0.6 0 0
Commercial Downtown 0.8 0 0
Industrial 0.8 0 0
Total 21814 18066
C=Weighted C Factor 0.83
2. Calculate Required Volume
Q = CIA
V=7200Q
C = Weighted C Factor 0.83
I = intensity (in/hr) 0.41 (10 yr, 2hr storm)
A = Area (acres) 0.50
Q = runoff (cfs) 0.17
V = REQUIRED VOL (ft3)1224
PROVIDED VOLUME 1,500
EX. RETENTION POND # 1A CONTRIBUTIONS FROM PROPOSED DA #1
REQUIRED VOLUME
1. Calculate Area and Weighted C Factor
Contributing Area C Area (ft 2)C * Area
ROW Hardscape 0.95 41211 39151
ROW Landscape 0.2 7493 1499
OS/Park 0.2 0 0
Low-Med Residential 0.35 0 0
Dense Residential 0.5 0 0
Commercial Neighborhood 0.6 0 0
Commercial Downtown 0.8 0 0
Industrial 0.8 0 0
Total 48704 40649
C=Weighted C Factor 0.83
2. Calculate Required Volume
Q = CIA
V=7200Q
C = Weighted C Factor 0.83
I = intensity (in/hr) 0.41 (10 yr, 2hr storm)
A = Area (acres) 1.12
Q = runoff (cfs) 0.38
V = REQUIRED VOL (ft3)2,755
PREVIOUSLY ALLOCATED VOLUME (ft3)2,840
APPENDIX E
EXISTING STORMWATER SYSTEM
Page 16 of 25
C = 0.75
Runoff Volume V = 0.068x0.75x29,964 ft2 = 1,534 ft3
Drainage Area 32:
Roof Area = 0 ft2
Hardscape Area = 4,877 ft2
Landscape Area = 748 ft2
__________
TOTAL = 5,625 ft2 Weighted Runoff Coefficient:
C = (0 ft2 x 0.85)+(4,877 ft2x0.90)+(748 ft2x0.20)
5,625 ft2 C = 0.81
Runoff Volume
V = 0.068x0.81x5,625 ft2 = 309 ft3
STORMWATER ROUTING (POST DEVELOPMENT)
Stormwater runoff from the drainage areas will be conveyed, via overland, pipe and gutter flow, to
retention ponds. The drainage area distribution is detailed below:
Retention Ponds 1A and 1B:
Drainage Areas flowing into Ponds 1A and 1B include: 1, 6, 12, 21, 21A, 21B, and 21C. Runoff from Resort Drive and Fallon Street (portions of Drainage Area 21) will follow existing patterns
and discharge to the existing storm drain inlet on the south side of Fallon Street, directly north of
Retention Pond 1A. The existing retention pond will be re-shaped as shown on the associated
construction plans.
Drainage Areas 1, 6, and 21A will discharge to a storm drain inlet (Inlet 1) on the south side of the
intersection of Valley Commons Drive and Boardwalk Avenue. A 15-inch PVC pipe will convey
water from Inlet 1 to Inlet 2, located on the north side of the same intersection. Inlet 2 will collect
all runoff from Valley Commons Drive (Drainage Area 21B). The combined flows from Inlets 1
and 2 will then flow in an 18-inch PVC pipe to Inlet 3, located on the south side of the Field Street and Boardwalk Avenue intersection. The combined flows from all inlets will then flow via a
21-inch PVC pipe to discharge at the bottom of Retention Pond 1B. The rest of Drainage Area 21
Page 17 of 25
will discharge to the ponds via surface flow. Retention Pond 1B will overflow to Retention Pond
1A if runoff volumes ever exceed Pond 1B’s capacity.
Total Volume Required: 25,347 ft3 (sum of runoff volumes from Drainage Areas: 1, 6, 12, 21, 21A, 21B, and 21C)
Total Volume Supplied: 20,660 ft3
Deficient Volume: 4,687 ft3
A concrete overflow structure with a 21-inch PVC outlet pipe will be constructed in Pond 1A to convey any overflow from Pond 1A to the existing retention pond in Lot 3A on the north side of Fallon Street. The current capacity of the existing pond on the north side of Fallon Street is
1,350 ft3. The proposed pond expansion will result in a total capacity of 6,387 ft3 – enough to
manage existing drainage and the addition of 4,687 ft3.
Retention Ponds 2A and 2B: Drainage areas flowing into Ponds 2A and 2B include: 16, 17, 27, and 31. Runoff from Drainage
Areas 16, 17, a portion of 27, and 31 will discharge to a new stormwater chase (Stormwater Chase
1 – sizing calculations below) located north of the Field Street and Resort Drive intersection. The
chase will route runoff into Retention Pond 2B. Pond 2B will overflow to Pond 2A if runoff volumes ever exceed Pond 2B’s capacity.
Volume Required: 6,607 ft3 (sum of runoff volumes from Drainage
Areas: 16, 17, 27, and 31)
Volume Supplied: 11,642 ft3
Surplus Volume: 5,017 ft3
Retention Pond 3: 803 ft3 of Drainage Area 8.
Volume Required: 803 ft3 Volume Supplied: 887 ft3
Retention Pond 4: 1,137 ft3 of Drainage Area 8.
Volume Required: 1,137 ft3 Volume Supplied: 2,720 ft3
Retention Pond 5: Drainage Area 9.
Volume Required: 1,361 ft3 Volume Supplied: 2,457 ft3
Retention Pond 6: Drainage Area 11.
Volume Required: 2,536 ft3 Volume Supplied: 2,720 ft3
STORMWATER MANAGEMENT
DESIGN REPORT
for
LOT 4, SPRING CREEK VILLAGE RESORT SUBDIVISION
MINOR SUBDIVISION NO. 295A)
Prepared for:
Delaney & Company, Inc.
101 East Main Street, Bozeman, MT 59715
Prepared by:
C & H Engineering and Surveying, Inc.
1091 Stoneridge Drive
Bozeman, MT 59718
406) 5 87-1115
Project No.: 11019
MARCH 2O14
INTRODUCTION
Lot 4, Spring Creek Village Resort Subdivision is located north of Huffine Lane (U.S. Highway
191), south of Fallon Street, west of Resort Drive and east of Cottonwood Road in Bozeman,
Montana. The 19.9621-acre development will consist of 20 commercial lots. This project will
include construction of all public improvements within the subdivision and will tie into existing
City ofBozeman water, sewer, and road networks.
Construction of the public improvements will take place first, which includes the construction of
public streets, water, sanitary sewer, and storm sewer facilities. The individual lots will be
developed after all improvements are in place.
STORMWATER MANAGEMENT
Stormwater runoff from the site will be directed by a storm sewer system and gutter flow to
retention ponds. These retention ponds will filter sediment and oils from the stormwater runoff.
The retention ponds are sized for the 10-year, 2-hour storm event while all storm sewer piping is
designed for the 25-year storm.
STORMWATER RUNOFF(POST DEVELOPMENT)
In accordance with City of Bozeman policy, the stormwater retention ponds must be sized for a
storm intensity having a 10-year frequency and a 2-hour duration. The equation used to model the
intensity of the 10-year frequency storm is given by the City of Bozeman Design Standards and
Specifications Policy(COB DSSP). The design intensity for this report was calculated as follows:
i=0.64(t-0•45) i=rainfall intensity(in/hr)
t=2 hrs t=storm duration(hours)
i =0.64(2-0.61)=0.408 in/hr=0.034 ft/hr d=2 hr water depth=0.068 ft
The stormwater runoff for all drainage areas on the attached drainage exhibit were calculated as
follows:
The stormwater runoff rate was calculated with the rational formula as shown. A runoff
coefficient(C) of 0.85 was applied to roof areas. A runoff coefficient(C) of 0.90 was applied to
hardscaping. A runoff coefficient (C) of 0.20 was applied to landscaping. The stormwater
runoff rate for each respective drainage area was calculated as follows:
Q=CiA Q=stormwater runoff rate(cfs)
i =(0.408 in/hr)x(1 ft/12 in)x(2 hr) C=weighted runoff coefficient
d=0.068 ft i =stormwater intensity(in/hr)
A=surface area of drainage area(ft') d=depth
V=CdA V=volume(ft')
Page 1 of 25
Drainage Area 1:
Roof Area 0 ft2
Hardscape Area 89,996 ft2
Landscape Area 32,141 ft2
TOTAL 122,137 ft
Weighted Runoff Coefficient:
C =(0 ft2 x 0.85)±(89,996 ft2x0.90)+(32,141 ftx0.20)
122,137 ft2
C =0.72
Runoff Volume:
V=0.068x0.72xl22,137 ft'=5,945 ft'
Drainage Area 2:
Roof Area 5,705 ft
Hardscape Area 0 ft
Landscape Area 0 ft
TOTAL 5,705 ft2
Weighted Runoff Coefficient:
C =(5,705 ft'-x 0.85)+(0 ft2x0.90)+(q ft2x0.20,
5,705 ft2
C =0.85
Runoff Volume
V =0.068x0.85x5,705ft2=419 ft-'
Drainage Area 3:
Roof Area 8,072 f12
Hardscape Area 0 ft2
Landscape Area 0 ft
TOTAL 8,072 ft
Page 2 of 25
Weighted Runoff Coefficient:
C =(8,072 ft2 x 0.85)+(0 ft2x0.90)+(0 ft'x0.20)
8,072 ft2
C =0.85
Runoff Volume
V=0.068x0.85x8,072 ft2= 192 ft'
Drainage Area 4:
Roof Area 13,281 ft2
Hardscape Area 0 ft2
Landscape Area 0 ft2
TOTAL 13,281 ft
Weighted Runoff Coefficient:
C =(13,281 ft2 x 0.85)+(0 ft2x0.90)+(0 ft2x0.20)
13,281 ft2
C =0.85
Runoff Volume
V=0.068x0.85x 13,281 ft2=768 ft'
Drainage Area 5:
Roof Area 4,355 W
Hardscape Area 0 ft2
Landscape Area 0 ft2
TOTAL 4,355 ft2
Weighted Runoff Coefficient:
C =(4,355 ft2 x 0.85)+(0 ff2x0.90)+f0 ft2x0.20)
4,355 ft2
C =0.85
Page 3 of 25
Runoff Volume
V=0.068x0.85x4,355 ft'=314 ft'
Drainage Area 6:
Roof Area 0 ft,
Hardscape Area 40,647 ft2
Landscape Area 15,369 ft'
TOTAL 56,015 ft'
Weighted Runoff Coefficient:
C =(0 ft'x 0.85)±(40,647 ft2x0.90)+(15,369 ft2x0.20)
56,015 ft2
C =0.71
Runoff Volume
V=0.068x0.7lx56,015 ft'= 2,697 ft'
Drainage Area 7:
Roof Area 8,792 ft'
Hardscape Area 0 ft2
Landscape Area 0 ft,
TOTAL 8,792 ft2
Weighted Runoff Coefficient:
C =(8,792 ft2X 0.85)+(0 ft2X0.90)+(0 ft2X0.20j
8,792 W
C =0.85
Runoff Volume
V=0.068x0.85x8,792 ft2=508 ft'
Drainage Area 8:
Roof Area 9,219 ft2
Hardscape Area 19,005 ft2
Landscape Area 17,958 ft2
Page 4 of 25
TOTAL 46,182 ft2
Weighted Runoff Coefficient:
C =(9,219 ft2 x 0.85)+(19,005 ft2x0.90)+(17,958 ft2x0.20)
46,182 ft2
C =0.62
Runoff Volume
V=0.068x0.62x46,182 ft2= 1,940 ft3
Drainage Area 9:
Roof Area 0 ft2
Hardscape Area 20,788 ft2
Landscape Area 6,553 ft2
TOTAL 27,341 ft2
Weighted Runoff Coefficient:
C =Lo ft2 x 0.85)+(20,788 ft2x0.90)(6,553 ftx0.20)
27,341 ft2
C =0.73
Runoff Volume
V=0.068x0.73x27,341 ft2= 1,361 ft3
Drainage Area 10:
Roof Area 5,718 ft2
Hardscape Area 0 ft2
Landscape Area 0 ft2
TOTAL 5,718 ft2
Weighted Runoff Coefficient:
C =(5,718 ft2 x 0.85)+(0 ft2x0.90)+(0 ft2x0.20)
5,718 ft2
Page 5 of 25
C =0.85
Runoff Volume
V =0.068x0.85x5,718 ft2=331 ft'
Drainage Area 11:
Roof Area 8,170 ft2
Hardscape Area 31,465 ft2
Landscape Area 10,122 ft2
TOTAL 49,757 ft2
Weighted Runoff Coefficient:
C =(8,170 ft2 x 0.85)+(31,465 ft2x0.90)+(10,122 ft2x020)
449,757 ft2
C =0.75
Runoff Volume
V=0.068x0.75x49,757 ft2=2,536 ft'
Drainage Area 12:
Roof Area 0 ft
Hardscape Area 22,326 ft
Landscape Area 2,385 ft2
TOTAL 24,712 ft
Weighted Runoff Coefficient:
C =(0 ft2 x 0.85) (22,326 ft2x0.90)+(2,385 ft2x020)
24,712 ft2
C =0.83
Runoff Volume
V=0.068x0.83x24,712 ft2= 1,399 ft'
Page 6 of 25
Drainage Area 13:
Roof Area 6,548 ft2
Hardscape Area 0 ft-
Landscape Area 0 ft2
TOTAL 6,548 ft2
Weighted Runoff Coefficient:
C =(6,548 ft2 x 0.85)+(0 ftax0.90)+(0 ft2x0.20)
6,548 ft2
C =0.85
Runoff Volume
V =0.068x0.85x6,548 ft2=378 ft3
Drainage Area 14:
Roof Area 6,560 ft2
Hardscape Area 0 ft2
Landscape Area 0 ft2
TOTAL 6,560 ft2
Weighted Runoff Coefficient:
C =(6,560 ft2 x 0.85)+(0 ft2x0.90)+(0 ft2x0.2oj
6,560 ft2
C =0.85
Runoff Volume
V =0.068x0.85x6,560 ft2=379 ft3
Drainage Area 15:
Roof Area 8,812 ft2
Hardscape Area 0 ft2
Landscape Area 0 ft2
TOTAL 8,812 ft2
Page 7 of 25
Weighted Runoff Coefficient:
C =(8,812 ft2 x 0.85)+(0 ft2x0.90)+(0 ft2x0.20)
8,812 ft2
C =0.85
Runoff Volume
V=0.068x0.85x8,812 ft2=509 ft3
Drainage Area 16:
Roof Area 0 ft2
Hardscape Area 22,242 ft2
Landscape Area 2,470 ft2
TOTAL 24,712 ft
Weighted Runoff Coefficient:
C =(0 ft2 x 0.85)±(22,242 ft2x0.90)+(2,470 ft2x0.20)
24,712 ft2
C =0.83
Runoff Volume
V=0.068x0.83x24,712 ft2= 1,395 ft3
Drainage Area 17:
Roof Area 0 ft2
Hardscape Area 27,266 ft2
Landscape Area 12,456 ft2
TOTAL 39,722 ft2
Weighted Runoff Coefficient:
C =(0 ft2 x 0.85)+(27,266 ft2x0.90)+(12,456 ft2x0.20)
39,722 ft2
C =0.68
Page 8 of 25
Runoff Volume
V=0.0680.6809,722 ft2= 1,838 ft3
Drainage Area 18:
Roof Area 8,812 ft
Hardscape Area 0 ft2
Landscape Area 0 ft2
TOTAL 8,812 ft2
Weighted Runoff Coefficient:
C =(8,812 ft2 x 0.85)+(0 ft2x0.90)+(0 ftx0.20)
8,812 ft2
C =0.85
Runoff Volume
V=0.068x0.85x8,812 ft2=509 ft3
Drainage Area 19:
Roof Area 6,560 ft2
Hardscape Area 0 ft2
Landscape Area 0 ft2
TOTAL 6,560 ft2
Weighted Runoff Coefficient:
C =(6,560 ft2 x 0.85)+(0 ft2x0.90)+(,0 ft2x0.2J0
6,560 ft2
C =0.85
Runoff Volume
V=0.068x0.85x6,560 ft2=379 ft3
Drainage Area 20:
Roof Area 6,548 ft2
Hardscape Area 0 ft2
Page 9 of 25
Landscape Area 0 ft2
TOTAL 6,548 ft2
Weighted Runoff Coefficient:
C =(6,548 ft2 x 0.85)+(0 ft2x0.901+(0 ft2x0.20
6,548 ft2
C =0.85
Runoff Volume
V=0.068x0.85x6,548 ft2=378 ft3
Drainage Area 21:
Roof Area 0 ft2
Hardscape Area 131,094 ft2
Landscape Area 87,994 ft2
TOTAL 219,088 ft2
Weighted Runoff Coefficient:
C =(0 ft2 x 0.85)+( 131,094 ft2x0.90)+(87,994 ft2x0.20)
219,088 ft2
C =0.62
Runoff Volume
V=0.068x0.62x219,088 ft2=9,220 ft3
Drainage Area 21A:
Roof Area 0 ft2
Hardscape Area 32,654 ft2
Landscape Area 11,381 ft2
TOTAL 44,036 ft2
Weighted Runoff Coefficient:
C =(0 ft2 x 0.85)+(32,654 ft2x0.90)+( 11,381 ft2x0.20)
44,036 ft2
Page 10 of 25
C =0.72
Runoff Volume
V=0.068x0.72x44,036 ft2=2,153 ft3
Drainage Area 21B:
Roof Area 0 ft2
Hardscape Area 40,648 ft2
Landscape Area 1,022 ft2
TOTAL 41,669 ft2
Weighted Runoff Coefficient:
C =(0 ft2 x 0.85)+(40,648 ft2x0.90)+( 1,022 ft2x0.20)
41,669 ft2
C =0.88
Runoff Volume
V=0.068x0.88x41,669ft2=2,502 ft3
Drainage Area 21C:
Roof Area 0 ft2
Hardscape Area 22,410 ft
Landscape Area 4,490 ft2
TOTAL 26,900 ft2
Weighted Runoff Coefficient:
C =(0 ft2 x 0.85)+(22,410 ft2x0.90)+(4,490 ft2x0.20)
26,900 ft2
C =0.78
Runoff Volume
V=0.068x0.78x26,900 ft2= 1,433 ft3
Page 11 of 25
Drainage Area 22:
Roof Area 19,620 ft2
Hardscape Area 0 ft2
Landscape Area 0 ft2
TOTAL 19,620 ft2
Weighted Runoff Coefficient:
C =(19,620 ft2 x 0.85)+(0 ft2xo.90)+(o ft2xo.20)
19,620 ft2
C =0.85
Runoff Volume
V =0.068x0.85x 19,620 ft2= 1,134 ft3
Drainage Area 23:
Roof Area 3,299 ft2
Hardscape Area 0 ft2
Landscape Area 0 ft2
TOTAL 3,299 ft2
Weighted Runoff Coefficient:
C =(3,299 ft2 x 0.85)+(0 ft2x0.90)+(0 ft2x0.200
3,299 ft2
C =0.85
Runoff Volume
V =0.0680.850,299 ft2 191 ft'
Drainage Area 24:
Roof Area 4,000 ft2
Hardscape Area 0 fe
Landscape Area 0 ft2
TOTAL 4,000 ft2
Page 12 of 25
Weighted Runoff Coefficient:
C =(4,000 ft2 x 0.85)+(0 ft2x0.90)+(0 ft2x0.20)
4,000 ft
C =0.85
Runoff Volume
V=0.068x0.85x4,000 ft2 231 ft?
Drainage Area 25:
Roof Area 3,299 ft2
Hardscape Area 0 ft2
Landscape Area 0 ft2
TOTAL 3,299 ft2
Weighted Runoff Coefficient:
C =(3,299 ft2 x 0.85)+(0 ft2x0.90)+(0 ft2x0.20)
3,299 ft
C =0.85
Runoff Volume
V=0.068x0.850,299 ft2= 191 ft3
Drainage Area 26:
Roof Area 15,186 ft2
Hardscape Area 0 ft
Landscape Area 0 ft2
TOTAL 15,186 ft
Weighted Runoff Coefficient:
C =(15,186 ft2 x 0.85)+(0 ft2x0.90)++(,0 ft2x0.20)
15,186 ft2
C =0.85
Page 13 of 25
Runoff Volume
V=0.068x0.85x 15,186 ft2= 878 ft3
Drainage Area 27:
Roof Area 0 ft2
Hardscape Area 22,586 ft2
Landscape Area 33,650 ft2
TOTAL 56,236 ft2
Weighted Runoff Coefficient:
C =(0 ft2 x 0.85)+(22,586 ft2x0.90)+(33,650 ft2x0.20)
56,236 ft2
C=0.48
Runoff Volume
V=0.068x0.48x56,236 ft2= 1,840 ft3
Drainage Area 28:
Roof Area 4,193 ft2
Hardscape Area 0 ft2
Landscape Area 0 ft2
TOTAL 4,193 ft'
Weighted Runoff Coefficient:
C =(4,193 ft2 x 0.85)+(0 ft2x0.90)+(0 ft2x0.20)
4,193 ft2
C =0.85
Runoff Volume
V =0.068x0.85x4,193 ft2=242 ft3
Drainage Area 29:
Roof Area 6,401 ft2
Hardscape Area 0 ft2
Page 14 of 25
Landscape Area 0 ft2
TOTAL 6,401 ft2
Weighted Runoff Coefficient:
C =(6,401 ft2 x 0.85)+(0 ft2x0.90)+(0 ft2x0.20
6,401 ft2
C =0.85
Runoff Volume
V=0.068x0.85x6,401 ft2=370 ft3
Drainage Area 30:
Roof Area 8,824 ft2
Hardscape Area 0 ft
Landscape Area 0 ft'-
TOTAL 8,824 ft2
Weighted Runoff Coefficient:
C =(8,824 ft2 x 0.85)+(0 ft2x0.90)+(0 ft2x0.20J
8,824 ft2
C =0.85
Runoff Volume
V=0.068x0.85x8,824 ft2 510 W
Drainage Area 31:
Roof Area 0 ft2
Hardscape Area 23,657 ft2
Landscape Area 6,307 ft2
TOTAL 29,964 ft2
Weighted Runoff Coefficient:
C =(0 ft2 x 0.85)+(23,657 ft2x0.90)+(6,307 ft2x0.20)
29,964 ft2
Page 15 of 25
C =0.75
Runoff Volume
V=0.068x0.75x29,964 ft2= 1,534 ft3
Drainage Area 32:
Roof Area 0 ft2
Hardscape Area 4,877 ft2
Landscape Area 748 ft2
TOTAL 5,625 ft2
Weighted Runoff Coefficient:
C =(0 ft2 x 0.85)+(4,877 ft2x0.90)+(748 ft2x0.20)
5,625 ft2
C =0.81
Runoff Volume
V=0.068x0.8lx5,625 ft2=309 ft'
STORMWATER ROUTING(POST DEVELOPMENT)
Stormwater runoff from the drainage areas will be conveyed,via overland,pipe and gutter flow,to
retention ponds. The drainage area distribution is detailed below:
Retention Ponds lA and 1B:
Drainage Areas flowing into Ponds IA and 1B include: 1, 6, 12, 21, 21A, 21B, and 21C. Runoff
from Resort Drive and Fallon Street(portions of Drainage Area 21) will follow existing patterns
and discharge to the existing storm drain inlet on the south side of Fallon Street, directly north of
Retention Pond IA. The existing retention pond will be re-shaped as shown on the associated
construction plans.
Drainage Areas 1,6,and 2 1A will discharge to a storm drain inlet(Inlet 1)on the south side of the
intersection of Valley Commons Drive and Boardwalk Avenue. A 15-inch PVC pipe will convey
water from Inlet 1 to Inlet 2, located on the north side of the same intersection. Inlet 2 will collect
all runoff from Valley Commons Drive (Drainage Area 21B). The combined flows from Inlets 1
and 2 will then flow in an 18-inch PVC pipe to Inlet 3, located on the south side of the Field Street
and Boardwalk Avenue intersection. The combined flows from all inlets will then flow via a
21-inch PVC pipe to discharge at the bottom of Retention Pond 1B. The rest of Drainage Area 21
Page 16 of 25
will discharge to the ponds via surface flow. Retention Pond 1 B will overflow to Retention Pond
1 A if runoff volumes ever exceed Pond IB's capacity.
Total Volume Required: 25,347 ft3 (sum of runoff volumes from
Drainage Areas: 1, 6, 12, 21, 21A,21B, and 21C)
Total Volume Supplied: 20,660 ft3
Deficient Volume: 4,687 ft3
A concrete overflow structure with a 21-inch PVC outlet pipe will be constructed in Pond I to
convey any overflow from Pond IA to the existing retention pond in Lot 3A on the north side of
Fallon Street. The current capacity of the existing pond on the north side of Fallon Street is
1,350 ft3. The proposed pond expansion will result in a total capacity of 6,387 ft3— enough to
manage existing drainage and the addition of 4,687 ft3.
Retention Ponds 2A and 2B:
Drainage areas flowing into Ponds 2A and 2B include: 16, 17, 27, and 31. Runoff from Drainage
Areas 16, 17,a portion of 27, and 31 will discharge to a new stormwater chase(Stormwater Chase
1 —sizing calculations below)located north of the Field Street and Resort Drive intersection. The
chase will route runoff into Retention Pond 2B. Pond 2B will overflow to Pond 2A if runoff
volumes ever exceed Pond 2B's capacity.
Volume Required: 6,607 ft3 (sum of runoff volumes from Drainage
Areas: 16, 17, 27, and 31)
Volume Supplied: 11,642 ft3
Surplus Volume: 5,017 ft3
Retention Pond 3: 803 ft3 of Drainage Area 8.
Volume Required: 803 ft3
Volume Supplied: 887 ft
Retention Pond 4: 1,137 ft3 of Drainage Area 8.
Volume Required: 1,137 ft3
Volume Supplied: 2,720 W
Retention Pond 5: Drainage Area 9.
Volume Required: 1,361 ft3
Volume Supplied: 2,457 ft
Retention Pond 6: Drainage Area 11.
Volume Required: 2,536 ft3
Volume Supplied: 2,720 ft3
Page 17 of 25
Retention Pond 7: Drainage Area 32.
Volume Required: 309 ft3
Volume Supplied: 338 ft'
Drywells: Drainage Areas 2,3,4, 5,7, 10, 13, 14, 15, 18, 19,20,22,23,24,25,
26, 27, 28, 29, and 30. All drainage areas flowing to drywells are
purely roof drainage areas. See Attachment 1 for an example
drywell calculation.
STORMWATER CHASE 1
Drainage Areas 16, 17, 31, and the east 206 if of Field Street (portion of Drainage Area 27) will
drain to a stormwater chase which will then convey water to Retention Pond 2B via swale. The
drainage area is 2.4530 acres,with a composite runoff coefficient calculated as follows:
Weighted Runoff Coefficient:
C =(12,456 ft2x0.88)+(24,712 ft2x0.83)+(39,722 ft2x0.68)+(29,964 ft2x0.75)
106,854 ft2
C =0.76
Runoff Volume
V= 0.068x0.76x106,854 ft2= 11,277 ft'
The stormwater chase will be a rectangular concrete channel as detailed in City of Bozeman
Standard Drawing No. 02529-14. The chase is designed to handle a 25-year storm event. The
post-development time of concentration from the most hydraulically remote section of the
drainage area is first calculated to determine the peak discharge:
Overland flow(614 ft @ 1.029%avg. slope, C--0.90)= 10.0 min(see Figure I-1, COB DSSP)
Gutter flow(543 ft @ 1.394%avg. slope, C=0.90)
V=(1.486/n)R21IS112 (n=0.013,A=1.24 ft2, P=9.23ft, R211=0.2623, S1C2=0.1181)
V=3.54 ft/s
T=543 ft/3.54 ft/s/60s/min 2.56 min
Page 18 of 25
Total Time of Concentration= 12.56 minutes(0.2093 hours)
For a 25-year storm event, Its =0.78X_'-"=0.78 (0.2093)-0-6'=2.12 in/hr
Q25=CIA=0.76 (2.12 in/hr) (2.4530 acres) =3.95 cfs
The chase will be 2.0 ft wide by 0.5 ft high. The capacity of a 2.0 ft x 0.5 ft rectangular channel at
the proposed slope of 2.5%is checked using Manning's equation:
Qa,11= (1.486/n)AR213Sv2
Manning's n=0.013 for concrete
Slope =0.025 ft/ft
A =area=wxh=2.0ftx0.5ft= 1.0ft'
P=wetted perimeter=w+2h=2.0 ft+ 1.0 ft=3.0 ft
R=hydraulic radius=A/P= 1.0/3.0=0.3333 ft
R213=0.4808 ft
S 1/-' =0.1581 ft/ft
Qa,11= (1.486/0.013)(1.0)(0.4808)(0.1581)=8.69 cfs
3.95 cfs < 8.69 cfs -+ 2.0ft x0.5ft chase @ 2.5%slope is adequate.
STORM SEWER PIPE NETWORK DESIGN-BOARDWALK AVE. &FIELD ST.
Three stonn drain inlets will be installed on Boardwalk Avenue to collect surface runoff from
Drainage Areas 1, 6, 21A, 21B, and 21C. Stone sewer manholes will be installed at the
intersection of Boardwalk Avenue and Field Street and at the west end of Field St to direct
stormwater to Retention Pond 1 B. All stonn water pipes are sized to handle the 25-year storm
COB DSSP). The pipe sizing calculations are presented below:
Inlet 1
First, it is necessary to calculate the time of concentration for stormwater runoff contributing to
Inlet 1 from Drainage Areas 1, 6, and 21A.
Overland flow-Landscape(133 ft @ 0.5%, C=0.2)=21.0 min(see Figure I-1, COB DSSP)
Overland flow-Pavement(482 ft @ 2.4%. C=0.9)=7.5 min(see Figure 1-1, COB DSSP)
Gutter flow along Boardwalk Ave. (82 ft @ 2.81%avg. slope)
Page 19 of 25
V=(1.486/n)R2"S112 (n=0.013,A=1.24 ft2, P=9.23ft,RZis=0.2623, S"2=0.1676)
V=5.03 ft/s
TC 82 ft/5.03ft/s/60s/min =0.27 min
Total Time of Concentration=21.0+7.5+0.27=28.8 minutes (0.4795 hours)
Next, the rainfall intensity of a 25-year storm with duration equal to the time of concentration is
calculated.
For a 25-year storm event: Its=0.78X-.64=0.78(0.4795)-.64= 1.25 in/hr(COB DSSP)
The composite runoff coefficient for the contributing Drainage Areas 1,6,and 2 1 A is calculated as
follows:
C=(122,137 ft2 x 0.72)+(56,015 ft2 x 0.71)+(44,036 ft220.72,)
222,191 ft2
C =0.72
The flow rate anticipated from Drainage Areas 1, 6, and 21A during a 25-year storm event is
calculated as follows:
Q25=CIA=(0.72)(1.25 in/hr)(5.1008 acres)=4.57 cfs
Finally, a 15-inch PVC pipe is checked for adequacy. The slope of the 72 ft section of pipe from
Inlet 1 to Inlet 2 is 0.80%. The capacity of the 15-inch PVC pipe is calculated as follows using
Manning's equation:
Manning's n =0.013 far PVC Pipe
Slope =0.008 ft/ft
A=area=(3.14/4)d 2=(3.14/4)(15/12)2= 1.2272 ft2
P=perimeter=2(3.14)r=2(3.14)(7.5/12)=3.9270 ft
R=hydraulic radius=A/P= 1.2272/3.9270=0.3125 ft
R2/3=0.4605 ft
S v2 =0.0894 ft/ft
Qfu11_ (1.486/0.013)(1.2272)(0.4605)(0.0894) =5.78 cfs>4.57 cfs (Q25) adequate
Page 20 of 25
The calculations show that a 15-inch PVC pipe will have adequate capacity to handle the runoff
from a 25-year storm.
Inlet 2
The time of concentration for stormwater runoff contributing to Inlet 2 from Drainage Area 2 1 B is
calculated as follows:
Overland flow(61.5 ft @ 0.93%,C=0.9) =2.0 min(see Figure I-1, COB DSSP)
Valley gutter flow along Valley Commons Dr. (307.6 ft @ 0.93%avg. slope)
V=(1.486/n)R2"S`2 (n=0.013, A=0.12 ft2, P=8.0 I ft, R2/3=0.0608, S"2=0.0964)
V=0.67 ft/s
To 307.6 ft/0.67ft/s/60s/min =7.65 min
Total Time of Concentration=2+7.65 =9.65 minutes (0.1608 hours)
Next, the rainfall intensity of a 25-year storm with duration equal to the time of concentration is
calculated.
For a 25-year storm event: I2s=0.78X--64 =0.78(0.1608)'.64=2.51 in/hr(COB DSSP)
Summary of given information for Drainage Area 2 1 B that contributes to Inlet 2:
Weighted Runoff Coefficient, C=0.88
Rainfall intensity for 25-year storm, I25=2.51 in/hr
Area=41,669ft2=0.9566acres
The flow rate anticipated from Drainage Area 21B during a 25-year storm event is calculated as
follows:
Q25=CIA=(0.88)(2.51 in/hr)(0.9566acres)=2.11 cfs
Because Inlet 2 is downstream of Inlet 1, the runoff contributing to Inlet 1 must be added to the
runoff contributing to Inlet 2 in order to determine an adequate pipe size at Inlet 2.
Q25_cumulative 4.57+2.11 =6.68 cfs
Page 21 of 25
An 18-inch PVC pipe is checked for adequacy. The slope of the 296 ft section of pipe from Inlet 2
to Inlet 3 is 0.84%.The capacity of the 18-inch PVC pipe is calculated as follows using Manning's
equation:
Manning's n =0.013 for PVC Pipe
Slope =0.0084 ft/ft
A=area=(3.14/4)d 2=(3.14/4)(18/12)2= 1.7671 ft2
P=perimeter=2(3.14)r=2(3.14)(9/12)=4.7124 ft
R=hydraulic radius=A/P= 1.7671 /4.7124=0.3750 ft
R2/3=0.5200 ft
S1/2 =0.0917 ft/ft
Qf,11= (1.486/0.013)(1.7671)(0.5200)(0.0917) =9.63 cfs>6.68 cfs (Q25) -+ adequate
The calculations show that an 18-inch PVC pipe will have adequate capacity to handle the runoff
from a 25-year storm.
Inlet 3
The time of concentration for stormwater runoff contributing to Inlet 3 from Drainage Area 21 C is
calculated as follows:
Gutter flow along Boardwalk Ave. (307.9 ft @ 0.77%avg. slope)
V=(1.486/n)R2/3S1/2 (n=0.013,A=1.24 ft2, P=9.23ft, R2/3=0.2623, S"2=0.0877)
V=2.63 ft/s
Tv=307.9 ft/2.63ft/s/60s/min = 1.95 min(0.0325 hours)
Next, the rainfall intensity of a 25-year storm with duration equal to the time of concentration is
calculated.
For a 25-year storm event: 125=0.78X'•'=0.78(0.0325)'.14=6.99 in/hr(COB DSSP)
Summary of given information for Drainage Area 2 1 C that contributes to Inlet 3:
Weighted Runoff Coefficient, C=0.78
Rainfall intensity for 25-year storm, I25=699 in/hr
Area--26,900ft2=0.6175acres
Page 22 of 25
The flow rate anticipated from Drainage Area 21C during a 25-year storm event is calculated as
follows:
Q25=CIA=(0.78)(6.99in/hr)(0.6175acres)=3.37 cfs
Because Inlet 3 is downstream of Inlets 1 and 2, the runoff contributing to Inlets 1 and 2 must be
added to the runoff contributing to Inlet 3 in order to determine an adequate pipe size at Inlet 3.
Q25 cumulative 4.57+2.11+3.37 = 10.05 cfs
Finally, a 21-inch PVC pipe is checked for adequacy. There are three sections of pipe that must
carry the 10.42 cfs of runoff. The critical section is the 339-ft run from STMH 1 to STMH 2 at a
slope of 0.44%.
The capacity of the 21-inch PVC pipe at this critical section is calculated as follows using
Manning's equation:
Manning's n =0.013 far PVC Pipe
Slope =0.0044 ft/ft
A=area=(3.14/4)d 2=(3.14/4)(21/12)2=2.4053ft2
P=perimeter=2(3.14)r=2(3.14)(10.5/12) =5.4978 ft
R=hydraulic radius=A/P=2,40553 /5.4978=0.4375ft
R"-'=0.5763 ft
S1/2 =0.0663 ft/ft
Qf„ll= (1.486/0.013)(2.4053)(0.5763)(0.0663)= 10.51 cfs> 10.05 cfs (Q25)--> adequate
The calculations show that a 21-inch PVC pipe will have adequate capacity to handle the runoff
from a 25-year storm from Inlet 3 to STMH 1, STMH 1 to STMH 2, and from STMH 2 to
Retention Pond 1 B.
OVERFLOW STRUCTURE—RETENTION POND lA
An overflow structure will be constructed in the south embankment of Retention Pond 1A.The top
of the structure elevation will be set to the top of pond elevation(4801.00)and will have a slotted
Page 23 of 25
grate cover to allow any overflow to drain. A 21-inch PVC pipe will convey water from the
overflow structure to the existing Retention Pond Lot 3A on the north side of Fallon Street. The
pipe is sized to handle the calculated peak runoff for a 25-year storm(10.05 cfs from calculations
for flow into Retention Pond 1 B). Previous calculations show that the capacity of a 21-inch pipe at
minimum slope is adequate to manage the peak flow rate.This outlet pipe will have a steeper slope
at 0.82%,providing additional capacity.
Page 24 of 25
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APPENDIX B
Sewer, Water & Stormwater, Design Report 4
Qfull = (1.486/0.013)(0.3491)(0.3029)(0.06325) = 0.7643 cfs
Qmax/Qfull = 0.4703 cfs/0.7643 cfs = 0.6154 or 61.54%
Based on the previous calculations the proposed 8-inch sewer mains are more than
adequate to carry the design flows for Ferguson Farms II.
Sanitary Sewer Service Sizing
To size the sewer services, the potential building use was considered for each floor. It
was assumed ground level floors were commercial, bar, restaurant, and retail. To be
conservative it was assumed each floor above ground level was office and medical, and
also a potential hotel area. 70% of the hotel area was assumed to contribute to hotel
rooms with the remaining 30% contributing to hallways, mechanical rooms, etc. Each
hotel room was assumed to be 300-ft2. Applying these assumptions yielded a number
of potential hotel rooms per lot. The flow rates from the 2022 IMEG Design Report
study were applied to these areas of potential use for each lot yielding a potential flow
rate for each lot. This analysis is summarized in Appendix A and determined a 4-inch
service is adequate throughout the development, however the largest lots (Block 1 Lot
1, Block 9 Lot 1, Block 10 Lot 3, and Block 6 Lots 2 & 3) were assigned a 6-inch
sanitary sewer service.
WATER SYSTEM
Ferguson Farm II will connect to the existing 8-inch water main under Resort Drive (two
locations), Ferguson Avenue (one location), and Fallon Street (two locations). All new
water mains will be located a minimum of 10-ft away from any proposed sewer and storm
mains and tree grates. All water mains will be looped, and internal hydrants will be
installed no more than 500-ft apart. Demand for the system was determined by adding
5% to the wastewater generation discussed in the previous section.
Hydrant flow test data from the fire hydrant located at the corner of Resort Drive and
Fallon Street (City of Bozeman fire hydrant #1751) indicates there is an available static
pressure of 128-psi at average daily demand and a residual pressure of 94-psi while
flowing 1,625-gpm. This information was used for the development of a pump curve to
be used in our model at the connection point. The connection point was modeled with
the above-mentioned pump and a reservoir, where the elevation of the pump, reservoir
and connection point are equal therefore the reservoir does not create any head on the
system modeled. The pump curve calculations and associated equations are included in
Appendix B.
WATER DISTRIBUTION SYSTEM SIZING
Average Daily Usage = Average Wastewater flow x 105%
= 74,462-gal/day x 1.05
= 78,185-gal/day
= 54.30-gal/min.
The following table displays the Average Daily Water Demand required by each Phase:
APPENDIX C
ST ST STSTSTSTSTTW:4840BW:48390'20'40'60'JANUARY 2026FERGUSON FARM OFFICE BUILDINGSTORM BASIN FIGURE Feb 05, 2026 - 10:57amCAD FILE: M:\254360\Drawings\FIGURES\STORM BASINS.dwg
1OF 1BASIN A0.53 ACRESBASIN B0.33 ACRESBASIN C0.23 ACRESEXISTING STORM WATER BASINPER FERGUSON PLAT NO. J-563HUFFINE TRAILHUFFINE LANEBOARDWALK AVEEXISTING STORM WATER RETENTION PONDVOLUME = 1586 CF(PER SPRING CREEK VILLAGE RESORT DEVELOPMENT)EXISTING CULVERT
APPENDIX D
10yrBasin Area (ac):0.5323,295.00 (sq ft)Post-Dev C (weighted):0.81Storm Duration (min)120.00Area Runoff (square feet) Coefficient CalculationsAsphaltic and Concrete18784.00 0.95 17844.80Heavy Soil (flat)0.17 0.00Heavy Soil (average)4511.00 0.22 992.42Drives, Walks and Roofs0.95 0.00Totals23295.00 18837.22Cw =0.81Storm Event (yr):2-yr, 2-hr 10-yr, 2-hr 25-yr, 2-hr 100-yr, 2-hr 100-yr, 24-hrCorrection Factors1.00 1.00 1.10 1.25 1.25Composite C:0.81 0.81 0.81 0.81 0.81Correction factor* C:0.81 0.81 0.89 1.01 1.01Storm Intensity (in/hr)*:0.24 0.41 0.49 0.61 0.10Post-Dev Qp (cfs):0.10 0.18 0.23 0.33 0.05V100YR/2HR :2,374.11cf V100YR/24HR :4,576.98cf10-Year, 2 Hour StormPond Area:234.00sfPond Area:234.00sfDuration Time:7,200.00sec Infiltration Rate:4.00in/hr Infiltration Rate:4.00in/hrV10YR/2HR :1,277cfVolume Infiltrated :156.00cf Volume Infiltrated :1,872.00cfMax Pond Storage: 502.00cf Max Pond Storage: 502.00cfMax Pond Capacity 658.00 cf Max Pond Capacity 2,374.00 cfCN= 91S= 1.0 inIa = 0.2 in0.5" - Ia=0.3 inV1/2":587 cf*Values are from COB Design Standards Figure 2 - Rainfall Intensity Duration in MinutesPond Size: 100 Year Storm (Includes Infiltration)Runoff Treatment Volume (Initial 0.5"):Ferguson Farm Office BuildingRetention System ADesign Storm Frequency =Design Storm: 10-Year, 2-Hour (City of Bozeman)Weighted Runoff Co-efficent:Runoff Rate (Rational Method):
10yrBasin Area (ac):0.3314,500.00 (sq ft)Post-Dev C (weighted):0.95Storm Duration (min)120.00Area Runoff (square feet) Coefficient CalculationsAsphaltic and Concrete0.95 0.00Heavy Soil (flat)0.17 0.00Heavy Soil (average)0.22 0.00Drives, Walks and Roofs14500.00 0.95 13775.00Totals14500.00 13775.00Cw =0.95Storm Event (yr):2-yr, 2-hr 10-yr, 2-hr 25-yr, 2-hr 100-yr, 2-hr 100-yr, 24-hrCorrection Factors1.00 1.00 1.10 1.25 1.25Composite C:0.95 0.95 0.95 0.95 0.95Correction factor* C:0.95 0.95 1.05 1.19 1.19Storm Intensity (in/hr)*:0.24 0.41 0.49 0.61 0.10Post-Dev Qp (cfs):0.08 0.13 0.17 0.24 0.04V100YR/2HR :1,736.11cf V100YR/24HR :3,346.98cf10-Year, 2 Hour StormPond Area:479.00sfPond Area:479.00sfDuration Time:7,200.00sec Infiltration Rate:4.00in/hr Infiltration Rate:4.00in/hrV10YR/2HR :934cfVolume Infiltrated :319.33cf Volume Infiltrated :3,832.00cfMax Pond Storage: 502.00cf Max Pond Storage: 502.00cfMax Pond Capacity 821.33 cf Max Pond Capacity 4,334.00 cfCN= 91S= 1.0 inIa = 0.2 in0.5" - Ia=0.3 inV1/2":365 cf*Values are from COB Design Standards Table 6.5.2- Rainfall Intensity Duration in MinutesPond Size: 100 Year Storm (Includes Infiltration)Runoff Treatment Volume (Initial 0.5"):Ferguson Farm Office BuildingRetention System BDesign Storm Frequency =Design Storm: 10-Year, 2-Hour (City of Bozeman)Weighted Runoff Co-efficent:Runoff Rate (Rational Method):
10yrBasin Area (ac):0.239,857.00 (sq ft)Post-Dev C (weighted):0.34Storm Duration (min)120.00Area Runoff (square feet) Coefficient CalculationsAsphaltic and Concrete0.95 0.00Heavy Soil (flat)0.17 0.00Heavy Soil (average)8222.00 0.22 1808.84Drives, Walks and Roofs1635.00 0.95 1553.25Totals9857.00 3362.09Cw =0.34Storm Event (yr):2-yr, 2-hr 10-yr, 2-hr 25-yr, 2-hr 100-yr, 2-hr 100-yr, 24-hrCorrection Factors1.00 1.00 1.10 1.25 1.25Composite C:0.34 0.34 0.34 0.34 0.34Correction factor* C:0.34 0.34 0.38 0.43 0.43Storm Intensity (in/hr)*:0.24 0.41 0.49 0.61 0.10Post-Dev Qp (cfs):0.02 0.03 0.04 0.06 0.01V100YR/2HR :423.73cf V100YR/24HR :816.90cf10-Year, 2 Hour StormPond Area:626.00sfPond Area:626.00sfDuration Time:7,200.00sec Infiltration Rate:4.00in/hr Infiltration Rate:4.00in/hrV10YR/2HR :228cfVolume Infiltrated :417.33cf Volume Infiltrated :5,008.00cfMax Pond Storage: 502.00cf Max Pond Storage: 502.00cfMax Pond Capacity 919.33 cf Max Pond Capacity 5,510.00 cfCN= 91S= 1.0 inIa = 0.2 in0.5" - Ia=0.3 inV1/2":248 cf*Values are from COB Design Standards Figure 2 - Rainfall Intensity Duration in MinutesPond Size: 100 Year Storm (Includes Infiltration)Runoff Treatment Volume (Initial 0.5"):Ferguson Farm Office BuidingRetention System CDesign Storm Frequency =Design Storm: 10-Year, 2-Hour (City of Bozeman)Weighted Runoff Co-efficent:Runoff Rate (Rational Method):