HomeMy WebLinkAboutMONTAVA - PHASE D CORE - BDR240006 - SUBMITTAL DOCUMENTS - ROUND 1 - Supporting Documentation (5)
Sanitary Sewer Analysis Results
For
Montava Phase D
submitted to:
Boxelder Sanitation
District
May 1, 2024
748 Whalers Way
Suite 200
Fort Collins, CO 80525
970.226.0557 main
970.226.0204 fax
ideas@tstinc.com
www.tstinc.com
May 1, 2024
Boxelder Sanitation District
3201 E Mulberry St
Unit Q
Fort Collins, CO 80524
Re: Montava Phase D Sanitary Sewer Analysis
Project No. 1230.0009.03
To whom it may concern:
TST, Inc. Consulting Engineers (TST) is pleased to submit this Montava Phase
D Sanitary Sewer Analysis to the Boxelder Sanitation District for review and
approval. This report includes our analysis of the infrastructure requirements
and our recommendations for providing services to this area for sanitary sewer.
Please review the attached report and provide any questions or comments at
your earliest convenience. We appreciate the opportunity to be of service to the
District and look forward to receiving your comments and moving forward on
this project.
Sincerely,
TST, INC. Consulting Engineers
Erika O’Rourke P.E.
EKO
I hereby certify that this report for the Montava Phase D Sanitary Sewer
Analysis was prepared by me or under my direct supervision in accordance
with the provisions of the Boxelder Sanitation District Specifications.
_________________________
Erika O’Rourke
Registered Professional Engineer
State of Colorado No. 62921
Montava Phase D Sanitary Sewer Analysis
TABLE OF CONTENTS
1.0 Introduction ...................................................................................................................... 1
1.1 Scope and Purpose ................................................................................................... 1
1.2 Project Location and Description ............................................................................... 1
1.3 Existing Conditions .................................................................................................... 2
2.0 Design Criteria & Assumptions ....................................................................................... 2
2.1 Sanitary Design Criteria and Assumptions ................................................................. 2
3.0 Proposed Sanitary Layout ............................................................................................... 2
3.1 Proposed Conditions ................................................................................................. 2
4.0 Sanitary Sewer Analysis & Results ................................................................................. 3
4.1 Sanitary Sewer Demand Calculations ........................................................................ 3
4.2 Sanitary Sewer System Analysis/Results ................................................................... 3
5.0 Conclusions & Recommendations .................................................................................. 3
6.0 Appendices ....................................................................................................................... 3
Montava Phase D Sanitary Sewer Analysis
Page 1
1.0 Introduction
1.1 Scope and Purpose
This report presents the results of the Sanitary Sewer Analysis for the Montava Phase D
Subdivision in Fort Collins, Colorado. This sanitary plan was prepared to identify infrastructure
needs as the area develops. Montava Phase D is surrounded by future Montava Subdivision
Phases, so the sanitary lines built with Phase D will be utilized to service the current and future
phases. Certain assumptions were made concerning the development of the future surrounding
properties. Updates to this Master Plan will be needed as plans for the future development of the
area are finalized and changes to the overall concept necessitate an update.
1.2 Project Location and Description
The proposed Montava Phase D Subdivision site is located west of N Giddings Rd between
Richards Lake Rd and Mountain Vista Dr in Fort Collins, Colorado and consists of
approximately 52 acres of undeveloped land. The proposed development contains 281 Single
Family lots, Tracts intended for future multi-family development, and open space.
Montava Phase D Sanitary Sewer Analysis
Page 2
1.3 Existing Conditions
The existing infrastructure around the Montava Subdivision includes a 21” Boxelder Sanitation
District trunk line that runs through the middle of the proposed Montava Phase D site. This 21”
trunk line carries effluent flow southeast through the Montava Subdivision. The layout of this
existing trunk line can be seen in Appendix A.
2.0 Design Criteria and Assumptions
2.1 Sanitary Design Criteria and Assumptions
The Boxelder Sanitation Districts Standards in combination with the Fort Collins Utilities Water and
Wastewater Design Criteria Manual, adopted on May 2, 2017 was used to design the alignment,
elevations, and sizing of internal sewer systems for Phase D.
Densities for the future Montava Phases were based on Table 3.1-1 of the Montava Development
Standards. The maximum density for each phase was utilized which is a conservative approach as
each phase will have a range between the maximum and minimum densities. The commercial
square footage was based on the Montava Development Yield Estimate for Water System
Analysis.
Sanitary Design Criteria
Average Daily Residential Demand = 75 gal/capita/day
Average People per Dwelling Unit = 3 capita/DU
School Site = 1,020 gal/day/ac
Commercial Demand = 500 gal/day/acre
Peaking Factor = 2.6 x Q average daily, cfs-0.16
Infiltration & Inflow = 0.347 gpm/ac
The minimum and maximum velocity at the design flow rate shall be two (2) fps
and ten (10) fps respectively
Manning’s Equation Friction Factor (“n”) = 0.013
3.0 Proposed Sanitary Layout
3.1 Proposed Conditions
The proposed sanitary consists of 15”, 12”, and 8” main lines that outfall into the existing 21”
Boxelder sanitary trunk line. Three connections to this existing mainline are proposed and the
extents of each sanitary “basin” along with the proposed sanitary sewer layout of Phase D and
approximate locations of future sanitary lines can be seen in the exhibit located in Appendix C.
The sewer sizing and layout has been determined based on demand calculations and analysis
that is discussed in section 4.0 of this report.
Montava Phase D Sanitary Sewer Analysis
Page 3
4.0 Sanitary Sewer Analysis and Results
4.1 Sanitary Sewer Demand Calculations
The previously mentioned criteria and assumptions were used to calculate the average day
residential and non-residential sanitary flows from each lot, tract, and future phase.
The average day effluent flow was applied to its associated upstream manhole and the cumulative
base flow was determined through each stretch of pipe. A peaking factor was determined from
each cumulative base flow value. Infiltration and inflows were determined based on the cumulative
area flowing to each manhole.
The peak effluent flow through each pipe was then determined by multiplying the cumulative base
flow by the peaking factor and adding the cumulative infiltration and inflow.
The peak effluent flow was converted from gallons per minute (gpm) to cubic feet per second (cfs).
The peak flow was then input into FlowMaster (10.03.00.03) where the Manning Formula was
utilized to determine velocities and flow depths within each pipe during peak events. All
calculations were done in an Excel spreadsheet and the velocities and % Full (d/D) values were
taken from FlowMaster and summarized within the Excel spreadsheet provided in Appendix D.
4.2 Sanitary Sewer Analysis and Results
Based on the result, the peak flow scenario indicated no modeled pipes exceeded a d/D capacity
of 80%. Eighteen pipes exceeded 50% d/D using the peak flow scenario. It should be noted that
the dwelling unit densities applied to the future phases are quite conservative so as each phase
develops an updated analysis with actual values should be analyzed and will likely result in
reduced peak effluent flows. The total peak effluent discharge was also calculated and determined
to be adequately handled by the existing 21” trunk line.
5.0 Conclusions and Recommendations
The Montava Phase D sanitary sewer has been designed to meet the Boxelder Sanitation District
Design Criteria and to adequately service the proposed and future Montava Subdivision. If there
are any questions or additional information needed, please do not hesitate to contact us.
6.0 Appendices
Appendix A – Existing Conditions
Appendix B – Density Assumptions
Appendix C – Proposed Sanitary Layout
Appendix D – Sanitary Sewer Analysis Results
!.!.!.!.!.
!.!.
!.
!.
!.
!.
!.!.!.
!.
!.!.!.
!.
!.
!.
!.
!.
!.!.!.!.
!.!.!.
!.
!.
!.
!.
!.
!.
!.
!.
!.
!.
!.
!.
!.
!.
!.
!.
!.
!.
!.!.!.!.!.!.!.!.!.
!.!.!.!.!.
!.!.!.
!.!.!.
!.!.
!.!.
!.
!.!.
!.!.
!.
!.
!.!.!.
!.
!.
!.!.!.!.!.!.!.
!.
!.!.!.
!.
!.!.
!.!.
!.!.!.!.!.
!.
!.!.!.
!.!.!.
!.
!.
!.!.!.!.!.!.
!.!.!.!.!.!.!.!.
!.
!.!.!.
!.!.!.
!.
!.
!.
!.
!.!.
!.!.
!.!.
!.
!.
!.
!.!.
!.
!.
!.!.
!.
!.
!.!.!.!.
!.
!.!.
!.!.!.!.!.!.!.
!.
!.!.!.!.
!.
!.!.!.
!.
!.
!.!.!.
!.
!.
!.!.!.!.!.
!.
!.!.!.!.!.!.!.!.!.!.
!.
!.
!.
!.
!.
!.!.!.
!.
!.
!.
!.
!.
!.
!.
!.
!.
!.
!.
!.!.!.
!.!.
!.
!.!.!.
!.
!.
!.!.!.
!.!.
!.!.!.!.!.!.!.!.!.
!.!.!.!.
!.!.
!.
!.!.!.!.!.!.!.!.
!.!.!.!.!.!.
!.!.
!.
!.
!.!.!.!.!.!.!.!.!.
!.
!.
!.
!.!.!.!.
!.!.
!.
!.
!.!.!.!.
!.
!.!.
!.!.!.!.
!.
!.!.
!.
!.!.!.
!.
!.
!.
!.
!.
!.!.
!.
!.!.!.
!.!.
!.!.!.
!.
!.!.!.!.!.
!.
!.
!.!.
!.
!.
!.
!.!.
!.!.!.
!.
!.!.!.!.
!.
!.
!.!.!.!.!.!.!.
!.!.!.
!.
!.!.!.!.!.!.
!.
!.
!.
!.
!.
!.!.!.!.!.
!.!.!.!.!.
!.
!.
!.!.
!.
!.
!.
!.!.!.
!.
!.!.
!.!.!.
!.
!.
!.!.!.!.!.
!.
!.!.
!.
!.
!.!.!.!.!.!.
!.
!.
!.!.
!.
!.
!.!.
!.
!.!.
!.
!.!.!.!.
!.
!.!.
!.
!.
!.
!.!.!.!.!.
!.!.
!.!.!.!.!.
!.
!.!.
!.!.
Lines & MHs added SBK4220 to SBK4200 - no as-built reference (April 2015)
Line here may be 12" only under ditch (April 2015)
Brightwater Landing
Maple Hill
Story Book
Story Book
Waterglen
0 1,400700
FeetOFacilities
!.WWTP
")Lift Station
%,E1 Points
Pipe Diameter
6, 8, 10 in
12, 15, 16, 18 in
21, 24 in
27, 30, 42 in
Jetter Sensitive
Preliminary Pipe
Pressure Mains
CDOT Force Main
Timnath Force Main
Walker Mfg. Force Main
E1 Force Main
Harmony Ridge FM
Larimer Parcel
BSD
!H <all other values>
MH By Sub-basin
!(CIS
!.BXI
!.CSI
!.DRI
!.DRI/PRI
!.OCI
!.PDI
AEI
BSI
CDOT
PLT
PRO
RAPS
TMG
WMPS
Production Date:2/20/2018 Pipe labels arelength, diameter, & type
<Title>
MONTAVA PHASE D SANITARY SEWER ANALYSIS
Offsite
Contribution From MH To MH
Diameter
(in)
Slope
(ft/ft)
Contributing
Units (DU)
Base Flow
(gpm)
Cummulative Base
Flow (gpm)
Peaking
Factor
I/I (gpm)
Cummulative
Peak Flow
Total (gpm)
Peak Flow
Total (cfs)
Velocity
(ft/s)% Full (d/D)
1M 1L 8 0.004 10 1.56 1.56 6.73 0.18 10.69 0.02 1.18 10.50 n = 0.013 Name Acres
Residential
Density (DU/Acre)Units (DU)Commercial/Office
(SF)
Commercial/Office
(gpm)
1L 1K 8 0.004 10 1.56 3.13 5.99 0.35 19.07 0.04 1.41 14.00 PF = 2.6 * Q(cfs)^-0.16 Future A 4.2 12 50.4 0 0.00
1AA 1K 8 0.004 8 1.25 1.25 6.99 0.18 8.91 0.02 0.94 11.10 capita/DU = 3 Tract BB 2.43 12 29.16 0 0.00
1K 1J 8 0.004 0 0.00 4.38 5.66 0.71 25.47 0.06 1.31 18.90 gal/capita/day = 75 Tract AA 2.13 30 63.9 0 0.00
1J 1I 8 0.004 0 0.00 4.38 5.66 0.88 25.65 0.06 1.31 18.90 1 cfs = 448.8 gpm Tract P 1.74 30 52.2 0 0.00
Future A 1BB 1BA 8 0.004 50.4 7.88 7.88 5.13 2.34 42.73 0.10 1.51 24.40
Average Daily Demand
(School)1020 gal/day/acre Phase A 42 10 420 0 0.00
1BA 1I 8 0.004 0 0.00 7.88 5.13 2.34 42.73 0.10 1.51 24.40 Infiltration & Inflow 0.347 gpm/acre Phase B 45 14 630 0 0.00
1I 1H 12 0.0022 0 0.00 12.25 4.76 2.34 60.67 0.14 1.29 19.60 Commercial/Office Demand 500 gal/day/acre Phase C1 21.5 14 301 8400 0.07
1H 1G 12 0.0022 0 0.00 12.25 4.76 2.34 60.67 0.14 1.29 19.60 Phase C2 21.5 14 301 8400 0.07
Tract BB 1G 1F 12 0.0022 29.16 4.56 16.81 4.51 3.19 79.06 0.18 1.39 22.20 Phase F 21 20 420 0 0.00
Tract AA 1F 1E 12 0.0022 63.9 9.98 26.79 4.17 3.92 115.77 0.26 1.55 26.70 Phase I 29 14 406 282200 2.25
Phase F 1E 1D 12 0.0022 420 65.63 92.42 3.39 11.21 324.55 0.72 2.05 45.90 Phase K 40 14 560 0 0.00
1D 1C 12 0.0022 0 0.00 92.42 3.39 11.21 324.55 0.72 2.05 45.90 Phase L 51 10 510 0 0.00
Phase K & I 1C 1B 15 0.0022 966 153.19 245.60 2.88 35.15 741.78 1.65 2.52 52.60 School 15 - - 0 0.00
1B 1A 15 0.0022 0 0.00 245.60 2.88 35.15 741.78 1.65 2.52 52.60
1A EX 15 0.0022 0 0.00 245.60 2.88 35.15 741.78 1.65 2.52 52.60
245.60 2.88 35.15 741.78 1.65
Offsite
Contribution From MH To MH
Diameter
(in)
Slope
(ft/ft)
Contributing
Units (DU)
Base Flow
(gpm)
Cummulative Base
Flow (gpm)
Peaking
Factor
I/I (gpm)
Cummulative
Peak Flow
Total (gpm)
Peak Flow
Total (cfs)
Velocity
(ft/s)% Full (d/D)
Phase C2 & L 2HB 2HA 12 0.0022 811 126.79 126.79 3.22 25.16 407.64 0.91 2.17 52.60
2HA 2AB 12 0.0022 0 0.00 126.79 3.22 25.16 407.64 0.91 2.17 52.60
Phase C1 2AC 2AB 8 0.004 301 47.10 47.10 3.80 7.46 178.84 0.40 2.21 51.40
2AB 2AA 12 0.0022 0 0.00 173.88 3.05 32.62 530.17 1.18 2.31 62.00
2AA 2G 12 0.0022 0 0.00 173.88 3.05 32.62 530.17 1.18 2.31 62.00
2K 2J 8 0.004 17 2.66 2.66 6.16 0.28 16.35 0.04 1.16 15.50
2J 2I 8 0.004 5 0.78 3.44 5.89 0.56 20.26 0.05 1.24 17.30
2GA 2I 8 0.004 3 0.47 0.47 8.24 0.83 3.86 0.01 0.77 8.00
2I 2H 8 0.004 4 0.63 4.53 5.63 1.11 25.50 0.06 1.31 18.90
2FA 2H 8 0.004 4 0.63 0.63 7.85 1.39 4.91 0.01 0.77 8.00
2H 2G 8 0.004 2 0.31 5.47 5.45 1.67 29.82 0.07 1.36 20.40
2G 2F 12 0.0022 0 0.00 179.35 3.03 34.58 544.01 1.21 2.32 63.10
2ED 2EC 8 0.004 7 1.09 1.09 7.14 0.29 7.81 0.02 0.94 11.10
2EC 2EB 8 0.004 0 0.00 1.09 7.14 0.58 7.81 0.02 0.94 11.10
2EB 2EA 8 0.004 8 1.25 2.34 6.29 0.87 14.73 0.03 1.06 13.50
2EA 2F 8 0.004 1 0.16 2.50 6.22 1.17 15.55 0.03 1.06 13.50
2F 2E 12 0.0022 4 0.63 182.48 3.02 36.03 551.88 1.23 2.33 63.80
2E 2D 12 0.0022 20 3.13 185.60 3.02 36.32 559.73 1.25 2.33 64.50
2BB 2BA 8 0.004 28 4.38 4.38 5.66 0.29 24.76 0.06 1.31 18.90
Tract P 2CA 2BA 8 0.004 68.2 10.66 10.66 4.87 0.60 51.94 0.12 1.60 26.80
2BA 2D 8 0.004 0 0.00 15.03 4.60 1.19 69.15 0.15 1.70 30.00
2DB 2DA 8 0.004 4 0.63 0.63 7.85 0.29 4.91 0.01 0.77 8.00
2DA 2D 8 0.004 19 2.97 3.59 5.85 0.58 21.02 0.05 1.24 17.30
2D 2C 12 0.0022 0 0.00 204.23 2.97 38.39 606.09 1.35 2.37 68.10
2C 2B 12 0.0022 0 0.00 204.23 2.97 38.68 606.09 1.35 2.37 68.10
4BB 4BA 8 0.004 4 0.63 0.63 7.85 0.24 4.91 0.01 0.77 8.00
4CA 4BA 8 0.004 8 1.25 1.25 6.99 0.24 8.73 0.02 0.94 11.10
4BA 4B 8 0.004 3 0.47 2.34 6.29 0.73 14.73 0.03 1.06 13.50
4C 4B 8 0.004 5 0.78 0.78 7.56 0.24 5.91 0.01 0.77 8.00
4B 4A 8 0.004 13 2.03 5.16 5.51 1.21 28.39 0.06 1.31 18.90
4A 2B 8 0.004 5 0.78 5.94 5.38 1.46 31.93 0.07 1.36 20.40
2B 2A 12 0.004 0 0.00 210.17 2.95 40.38 620.71 1.38 2.38 69.30
3AC 3AB 8 0.004 3 0.47 0.47 8.24 0.16 3.86 0.01 0.77 8.00
3AB 3AA 8 0.004 8 1.25 1.72 6.62 0.31 11.38 0.03 1.06 13.50
3AA 3F 8 0.004 0 0.00 1.72 6.62 0.47 11.38 0.03 1.06 13.50
3BA 3G 8 0.004 2 0.31 0.31 8.82 0.16 2.76 0.01 0.77 8.00
3H 3G 8 0.004 2 0.31 0.31 8.82 0.16 2.76 0.01 0.77 8.00
3G 3F 8 0.004 5 0.78 1.41 6.85 0.47 9.63 0.02 0.94 11.10
3F 3E 8 0.004 6 0.94 4.06 5.73 0.62 23.28 0.05 1.24 17.30
3E 3D 8 0.004 1 0.16 4.22 5.69 0.78 24.03 0.05 1.24 17.30
3D 3C 8 0.004 4 0.63 4.84 5.56 0.94 26.95 0.06 1.31 18.90
3C 3B 8 0.004 0 0.00 4.84 5.56 1.09 26.95 0.06 1.31 18.90
3B 3A 8 0.004 0 0.00 4.84 5.56 1.25 26.95 0.06 1.31 18.90
3A 2A 8 0.004 0 0.00 4.84 5.56 1.41 26.95 0.06 1.31 18.90
215.01 2.94 41.78 674.37 1.50
Offsite
Contribution From MH To MH
Diameter
(in)
Slope
(ft/ft)
Contributing
Units (DU)
Base Flow
(gpm)
Cummulative Base
Flow (gpm)
Peaking
Factor
I/I (gpm)
Cummulative
Peak Flow
Total (gpm)
Peak Flow
Total (cfs)
Velocity
(ft/s)% Full (d/D)
Phase A & B 5DA 5E 12 0.0022 1050 164.06 164.06 3.08 30.19 505.13 1.13 2.28 60.30
School 5F 5E 8 0.004 15 10.63 10.63 4.88 5.21 51.81 0.12 1.60 26.80
5E 5D 12 0.0022 0 0.00 174.69 3.05 35.72 532.21 1.19 2.31 62.40
5BB 5BA 8 0.004 11 1.72 1.72 6.62 0.33 11.38 0.03 1.06 13.50
5CA 5BA 8 0.004 2 0.31 0.31 8.82 0.33 2.76 0.01 0.77 8.00
5BA 5D 8 0.004 2 0.31 2.34 6.29 0.99 14.73 0.03 1.06 13.50
5D 5C 12 0.0022 2 0.31 177.34 3.04 37.04 538.93 1.20 2.31 62.70
5DA 5AA 8 0.004 4 0.63 0.63 7.85 0.33 4.91 0.01 0.77 8.00
5AB 5AA 8 0.004 2 0.31 0.31 8.82 0.33 2.76 0.01 0.77 8.00
5AA 5C 8 0.004 10 1.56 2.50 6.22 0.99 15.55 0.03 1.06 13.50
5C 5B 12 0.0022 9 1.41 181.25 3.03 38.36 548.79 1.22 2.32 63.40
5B 5A 12 0.0022 4 0.63 181.88 3.03 38.69 550.36 1.23 2.33 63.80
6B 6A 8 0.004 6 0.94 0.94 7.33 0.33 6.87 0.02 0.94 11.10
6A 5A 8 0.004 0.00 0.94 7.33 0.66 6.87 0.02 0.94 11.10
182.81 3.02 39.35 592.07 1.32
21 0.0011 4050 643.42 2.45 116.29 1690.95 3.77 2.38 62.6
Ex 21" Ult. Outfall
Assumptions
Total
Total
Offsite Contribution Assumptions
Sa
n
i
t
a
r
y
B
a
s
i
n
3
Montava Phase D Sanitary Sewer Analysis
Sa
n
i
t
a
r
y
B
a
s
i
n
2
Total
Sa
n
i
t
a
r
y
B
a
s
i
n
1
APPENDIX D
748 Whalers Way, Suite 200 Fort Collins, CO 80525 ideas@tstinc.com
970.226.0557 main 970.226.0204 fax www.tstinc.com