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Blackmore Bend
Public Utilities Design Report
May 2017
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TABLE OF CONTENTS
Introduction...............................................................................................................1
ProjectDescription .................................................................................................. 1
Construction Drawings............................................................................................... 1
DesignCriteria........................................................................................................ 1
Evaluation of Potential Impacts - Sanitary Sewer ..................................................................2
Historical Wastewater Flows ....................................................................................... 2
Proposed Wastewater Flow......................................................................................... 3
SanitarySewer Main............................................................................................... 3
On-site Sanitary Sewer Improvements ............................................................................ 4
Sanitary Sewer Service............................................................................................ 4
Evaluation of Potential Impacts - Water Main.......................................................................5
WaterUse Data....................................................................................................... 5
FlowRequirements................................................................................................... 5
List of Figures and Tables
Table 1: Historical Water Usage...................................................................................... 2
Table2: Total Demand................................................................................................. 3
Table 3: Estimated Average Day Flow during Operating Hours.................................................. 4
Appendices
Appendix A: Sanitary Sewer Demand
Appendix B: Hydrant Pressure Tests
Blackmore Bend
Public Utilities Design Report i
INTRODUCTION
This report includes the sanitary sewer and water main design information for Blackmore Bend - Phase I
development. The information is intended to illustrate the impacts of Phase I sewer and water utilities
on the City of Bozeman's existing systems.
Project Description
The proposed development, Blackmore Bend, is located along East Main Street between Highland
Boulevard and Haggarty Lane. The development will improve a mixed-use commercial vacant lot that
previously consisted of the Continental Motor Inn, KO's Club and Rainbow Auto (all of which have been
demolished). Phase I of the project includes the construction of a new 40,500 square foot marketplace
building in the southwest corner of the site. The marketplace building will consist of a ground floor
grocery, mezzanine level dining area and two second floor office spaces. In addition to the marketplace
building, Phase I will also include all necessary sanitary sewer and water main to adequately serve the
site.
The existing sanitary sewer main is currently aligned under a future planned building. In order to prepare
the site for Phases 2 Et 3, the sanitary sewer main must be realigned around future building footprints.
The following items are proposed as part of the sanitary sewer main and service requirements:
• Replacement of approximately 230 feet of existing 10-inch vitrified clay sanitary sewer main with
300 feet of new 10-inch PVC sanitary sewer main.
o Sewer main to include all necessary appurtenances.
• New 6-inch PVC sanitary sewer service to serve the marketplace building.
o Sewer service to include all necessary appurtenances such as cleanouts.
There is no existing water main located on site. Therefore, Phase I of the project will include extending
water main into the site to serve the marketplace building and the future buildings of Phases 2 Et 3. It is
proposed that connection to the City's distribution system occur along Highland Boulevard at the existing
hydrant tee located near the southern property line. In order to account for future development and
looping, a dead end main would be extended along the center access to East Main Street and terminated
with a fire hydrant for flushing. This would allow for future connection to the existing system if and/or
when utilities along East Main Street are updated.
The following items are proposed as part of the water main requirements:
• Approximately 1,100 feet of 8-inch ductile iron water main and 300 feet of 6-inch ductile iron
water main.
o Proposed ductile iron water main will include all necessary valves, fittings, services and
fire leads.
Construction Drawings
Construction drawings for the project, including location and alignments, can be found attached as part
of this submittal package.
Design Criteria
Design criteria is in accordance with Montana DEQCircular 2- Design Standards for Public Sewage Systems
and Circular 4 - Montana Standards for Subsurface Wastewater Treatment Systems as well as City of
Bozeman Design Standards and specifications policy.
Blackmore Bend
Public Utilities Design Report Page 1 of 6
EVALUATION OF POTENTIAL IMPACTS - SANITARY SEWER
Historical water usage was provided from the City and it is assumed that historical wastewater flow rates
are equivalent as the site was mostly impervious with minimal irrigation. The following sanitary sewer
analysis will evaluate historical rates and compare with the proposed wastewater flows to determine
impacts, if any, on the City of Bozeman's existing sanitary sewer system.
Historical Wastewater Flows
Historical water usage was derived from utility bills for the previously existing Continental Motor Inn,
KO's Club and Rainbow Auto dating 1999 to 2011. It is worth noting that these bills reflect a time period
where all three buildings were transitioning from active businesses to permanent closures. The following
table, Table 1: Historical Water Usage, depicts the historical average daily flows for each business.
Average daily flows for each year were determined by evaluating each month's total flow, dividing by
the number of days in the corresponding billing period and averaging all the months of a specific year to
obtain a gallon per day value.
Table 1: Historical Water Usage
Continental
Motor Inn • Rainbow
Year Average Daily Flow (gpd)
1999 5,082.5 2,690.4 511.8
2000 5,616.7 3,019.9 469.4
2001 4,973.7 3,256.9 626.4
2002 2,979.1 1,245.8 611.4 i
2003 5,463.6 1,239.2 667.0
2004 5,463.6 1,365.5 507.8
2005 7,015.4 1,332.6 818.4
2006 7,385.0 1,576.4 846.3
2007 ---------- 1,925.0 658.7
2008 ---------- 1,978.9 590.8
2009 ---------- 1,669.1 618.8
2010 ---------- 1,139.2 673.3
2011 ---------- 1.3 367.8
I
The following table, Table 2: Total Demand, shows the total daily demand (building demands combined)
of the site under previous developed conditions. To calculate average demands during operating hours it
was assumed daily operating hours for Continental Motor Inn were 18, KO's Club 12 and Rainbow Auto
11.
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Blackmore Bend
Public Utilities Design Report Page 2 of 6
Table 2. Total Demand
• • i I • ' FLOWS
Average Daily Average Demand During
Year Flow Operating Hours
(gpd) m
1999 8,284.7 9.2
2000 9,106.0 10.1
2001 8,857.0 10.1
2002 4,836.3 5.4
2003 7,369.8 7.8
2004 7,336.9 7.7
2005 9,166.4 9.6
2006 9,807.7 10.3
2007 2,583.7 3.7
2008 2,569.7 3.6
2009 2,287.9 3.3
2010 1,812.5 2.6
2011 369.1 0.6
As can be seen in the above table, the maximum site water usage from the information provided occurred
in 2006 and resulted in an average demand during operating hours of 9,807.7 gpd or 10.3 gpm. As
previously stated, this is believed to be equivalent to historical wastewater flow rates.
Proposed Wastewater Flow
As stated above, Phase I of the project will require the replacement of an existing 10-inch sanitary sewer
main as well as a new 6-inch sanitary sewer service to serve the marketplace building.
Sanitary Sewer Main
To determine the anticipated average day wastewater flows of the marketplace building, Montana DEQ,
Circular 4, Table 3.1-1 was utilized. See Table 3: Estimated Average Day Flow during Operating Hours for
the assumptions made and the resulting wastewater flows for the marketplace building.
Blackmore Bend
Public Utilities Design Report Page 3 of 6
Table 3: Estimated Average Day Flow during Operating Hours
Average Average Flow
Area DEQ Demands During
(ftz) Assumptions (gpd) Daily Flow Operating Hours
(Sp(gpd) m
• Operating Hours - 14
• 72 Employees with
Grocery 18,369 24 on shift at a time 10 gpd/employee 240 gpd 0.3 gpm
Store Nine Stalls (use 500 gpd/stall 4,500 gpd 5.4 gpm
department store
stall demand)
• Operating Hours - 10
Office 13,023 Maximum Occupancy 13 gpd/employee 350 gpd 0.6 gpm
Space of 26.9 (per
architect
• Operating Hours - 14
Dining Maximum Occupancy
Area 1,281 of 22 (per architect) 3 gpd/meal 300 gpd 0.4 gpm
• Assume 100 meals
per day _
• Demand included in
Warehouse 3,391 grocery store --------- -------- -
section
Total 5,390 gpd 6.7 gpm
As can be seen in the table above, the estimated average wastewater flow during operating hours is 6.7
gpm and is less than the known maximum historical usage of 10.3 gpm. Therefore, of the site will not
see an increase in overall usage and the City of Bozeman's sanitary sewer system will not be adversely
impacted by Phase I of the development.
On -site Sanitary Sewer Improvements
A 6-inch sanitary sewer service is necessary to serve the marketplace building. This was determined
based on a total fixture count of 360 water supply fixture units (wfsu) supplied by the mechanical
engineer. Using the International Plumbing Code, Table E103.3, the peak instantaneous demand
corresponding to 360 wfsu is 97 gpm. The table used to determine total fixture counts can be found in
Appendix A: Sanitary Sewer Demand, at the end of this report.
Sanitary Sewer Service t
Comparing peak flow to the maximum flow through a 6-inch sewer service determined there is more than
enough capacity in the pipe to handle the anticipated flows from the market place building. See
calculations below:
• Q=A(kn/n) R(1i3) S(1/z)
• A= 0.158 ft2
o Calculated area based 0.75 percent full 6" pipe
• kn = 1.486
o English units conversion
• n = 0.013
o Manning Coefficient of Roughness for ductile iron pipe
• R = 0.151 ft
Blackmore Bend
Public Utilities Design Report Page 4 of 6
410/
o Calculated hydraulic radius based on 0.75 percent full pipe (City maximum)
• S = 0.02
o Based on City of Bozeman minimum slope of service line
• Q= 0.724 ft3/s = 325.2 gpm
At 325 gpm, the proposed 6-inch sanitary sewer service has more than enough capacity for the peak
instantaneous flow of 97 gpm. It should also be noted, that it is anticipated the proposed site will
experience similar flows to the previous uses and as such will have similar peaking factors.
EVALUATION OF POTENTIAL IMPACTS - WATER MAIN
The following water main analysis evaluates proposed water use data as well as flow requirements at the
site to determine the impacts, if any, on the City of Bozeman's existing distribution system as a result
of Phase I.
Water Use Data
As the proposed extension is located in an established, predeveloped, land locked neighborhood and due
to the area of the site, the development will not allow for future growth. Therefore, all proposed water
main has been designed to meet the demands of the development.
Flow Requirements
The proposed water main extension would be fed from existing mains located along Highland Boulevard
and the property to the south. Hydrant pressure tests were completed at two hydrants located near the
site at the intersection of East Main Street and Highland Boulevard as well as the Private Drive located
near the second connection. The results of the hydrant pressure tests indicate there is 126 psi of static
pressure present near the site. Results also indicated a residual pressure of 120 psi at a flow of 1,710
gpm. See Appendix B: Hydrant Pressure Tests for the results of the pressure testing.
The City of Bozeman requires a minimum working residual pressure of 20 psi at all points in the system
under maximum day demands plus fire flow conditions. The ratio of average day demand to maximum
day demand typically ranges from 1.2 for larger systems to 3.0 for smaller systems. As this is a very small
system, it is assumed that maximum day demand is equivalent to three times the average day demand.
To determine if the pressure would remain adequate with the addition of the extension, the pressure
loss anticipated during required conditions in each branch from connection point to convergence were
calculated. The following values were used: j
• Pj.,, = 4.53 x L x [(Q/C)l.852/ (D)4.857]
• Branch 1 - Highland Boulevard Connection to Convergence- 4.3 psi pressure loss
o L= 245ft
o Q= 1,500 gpm (fire flow condition) + 6.4 gpm x 3 (maximum day demand) = 1,519.2 gpm
o C = 130, DI pipe
o D = 8in
• Branch 2 - Hydrant Tee (southern property edge) to Convergence- 7.9 psi pressure loss
o L= 450 ft
o Q= 1,500 gpm (fire flow condition) 6.4 gpm x 3 (maximum day demand) = 1,519.2 gpm
o C = 130, DI pipe
o D = 8in
• Branch 3 - Convergence to Dead End Hydrant (near East Main) - 4.4 psi pressure loss
o L= 250 ft
Blackmore Bend
Public Utilities Design Report Page 5 of 6
o Q= 1,500 gpm (fire flow condition) 6.4 gpm x 3 (maximum day demand) = 1,519.2 gpm
o C = 130, DI pipe
o D = 8in
Under these conditions, and with an existing residual pressure of 120 psi, there is more than enough
available pressure to account for the anticipated pressure losses resulting from the water main extension
during fire flow scenarios.
In addition to the hydrant pressure test indicating there is adequate pressure present, by adding the new
main the site will loop the City of Bozeman's existing system.There are many benefits to a looped system
one of the most important being an increased pressure and flow at hydrants when compared to hydrants
at dead end mains.
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Blackmore Bend
Public Utilities Design Report Page 6 of 6
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Appendix A: Sanitary Sewer Demand
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Appendix B: Hydrant Pressure Tests
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CITY OF BOZEMAN Our,z Tulure'I'pgelher
HYDRANT PRESSURE/FLOW REQUEST FORM
Date: 11/10/16
Location Hydrant# Static Pressure Pitot Pressure Residual Pressure
Main/Highland 545 104
Private Dr. 553 126 120
Requested By: Shane Strong
Fax#
Nozzle Size Flowed: 2.5"
Done By: ES /KD
Comments: 1710 GPM
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2328 ~•-,- 220 •
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