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EXCEPTIONAL HEALTHCARE
Stormwater Drainage Report
Exceptional Healthcare Bozeman
Planning Application Number - 24318
Northwest corner of Frontage Road (IH90) and Nelson Road
City of Bozeman, Montana
PREPARED FOR
Exceptional Healthcare
3514 Cedar Springs Road
Dallas, Texas 75219
January 2025
PREPARED BY
DEVELOPMENT ENGINEERING CONSULTANTS, LLC
5300 TOWN & COUNTRY BOULEVARD, SUITE 150
FRISCO, TEXAS 75034
469-850-0060 | dec-en.com
December 2024
Storm Drainage Report – Exception Healthcare Bozeman
DEC Job No. 10875
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DEC · 5300 Town & Country Boulevard, Suite 150 · Frisco, Texas 75034 · 469-850-0060
TABLE OF CONTENTS
INTRODUCTION ........................................................................................................... 3
HYDROLOGY ................................................................................................................ 4
Existing Conditions .................................................................................................................................................4
Proposed Conditions ..............................................................................................................................................5
Runoff Calculations .................................................................................................................................................5
Stormwater Retention Calculations .......................................................................................................................8
GROUNDWATER AND SOILS INFORMATION ............................................................... 14
CONCLUSION .............................................................................................................. 18
APPENDIX A – DRAINAGE AREA EXHIBIT ..................................................................... 19
Figures
Figure 1: Location Map ............................................................................................................................... 3
Figure 2 Nelson Meadows - Comprehensive Drainage Plan ...................................................................... 4
Figure 3: NRCS Soils Map .......................................................................................................................... 15
Figure 4: Groundwater Depth Comprehensive Drainage Plan for Nelson Meadows .............................. 16
Figure 5: Groundwater Monitor Wells - Comprehensive Drainage Plan for Nelson Meadows ............... 17
Tables
Table 1: Time of Concentration – Sheet Flow ............................................................................................. 5
Table 2: Time of Concentration – Shallow Flow ......................................................................................... 6
Table 3: Time of Concentration Calculations Concentrated Flow and Total Tc ......................................... 6
Table 4: Weighted C Calculations ............................................................................................................... 7
Table 5: Runoff Calculations ....................................................................................................................... 7
Table 6: Pond 1 Runoff Reduction Volume ................................................................................................. 8
Table 7: Pond 1 Retention Volume ............................................................................................................. 8
Table 8:Pond 2 Runoff Reduction Volume .................................................................................................. 9
Table 9: Pond 2 Retention Volume ............................................................................................................. 9
Table 10: Pond 3 Runoff Reduction Volume ............................................................................................. 10
Table 11: Pond 3 Retention Volume ......................................................................................................... 10
Table 12: Pond 1 Appendix C DEQ Volume ............................................................................................... 11
Table 13: Pond 2 Appendix C DEQ Volume ............................................................................................... 12
Table 14: Pond 3 Appendix C DEQ Volume ............................................................................................... 13
Table 15: Pond Volume Calculassions....................................................................................................... 14
December 2024
Storm Drainage Report – Exception Healthcare Bozeman
DEC Job No. 10875
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DEC · 5300 Town & Country Boulevard, Suite 150 · Frisco, Texas 75034 · 469-850-0060
INTRODUCTION
The project is a 3.78-acre medical office project located on lots 21 and 22 of the Nelson Meadows
Business Park. The site is located at the northwest corner of IH90 Frontage Road and Nelson Road. The
Exceptional Healthcare site is located on Lots 21 and 22, Block 1 of the Nelson Meadows Subdivision.
The project is zoned Light Manufacturing (M-1). The project will consist of a medical office building. The
stormwater system has been designed utilizing the City of Bozeman Design Standards and Specifications.
Figure 1: Location Map
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HYDROLOGY
The modified rational method was used to determine the existing and proposed flows and to determine
the retention volumes. The existing basin utilized the runoff coefficient, C=0.20. The proposed runoff
coefficient was computed based on the impervious area of the project improvements.
Existing Conditions
Currently the site is vacant land with existing slopes from 1% - 2%. The site is in the Royal Wolf Way plus
Prince Lane (RWW & PL) drainage basin in the Comprehensive Drainage Plan for Nelson Meadows
(Morrison Maierle, March 2019). The site is at the top of the basin. There are no existing stormwater
improvements on the site. Rainfall drains to the northwest corner and is absorbed onsite through
infiltration and absorption. The site flows from the southeast corner to the northwest side of the
property.
Figure 2 Nelson Meadows - Comprehensive Drainage Plan
SITE
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Proposed Conditions
The proposed site will drain to three retention areas located at the northwest (Pond 1), northeast (Pond
2, and southeast (Pond 3) of the property. The storm water for Ponds 1, 2 and 3 will be directed to the
retention ponds with grading, curb and gutter and swales to the downstream elevation on the site. Pond
1 will incorporate an inlet and storm sewer pipe. The storm water will be captured and contained on
the site.
The retention ponds will be regularly maintained by the property owner, Exceptional Healthcare Inc. The
ponds and drainage infrastructure will be visually inspected monthly. When the monthly inspection
warrants, the ponds will be mowed and the curb openings and inlet unclogged as needed. Overtime, as
sediment collects, sediment removal will be required to restore the pond volumes. Sediment
accumulation will be inspected annually. When the sediment inspection warrants, sediment removal
will be completed.
Runoff Calculations
The 2-year, 10-year and 100-year storm intervals were used to analyze the storm water runoff for the
site. The time of concentration, C factor and rainfall was computed for the three ponds.
Table 1: Time of Concentration – Sheet Flow
Pre Development
L US Elev DS Elev S P2
(ft)(ft)(ft)(ft/ft)(in)n (hr)(min)
1 100 4608.26 4606.00 0.023 1.13 0.15 0.26 15.7
2 35 4611.94 4610.96 0.028 1.13 0.15 0.10 6.2
3 33 4610.00 4609.88 0.004 1.13 0.15 0.22 13.4
Post Development
L US Elev DS Elev S P2
(ft)(ft)(ft)(ft/ft)(in)n (hr)(min)
1 116 4609.58 4607.44 0.018 1.13 0.011 0.04 2.4
2 35 4611.86 4610.09 0.050 1.13 0.15 0.08 4.9
3 32 4609.90 4609.58 0.010 1.13 0.15 0.15 8.7
Sheet Flow
Mannings Kinematic Solution
tc(hr.)=0.007(nL)0.8
P2
0.5S0.4
Time of Concentration Calculations
Sheet Flow
Sheet Flow
Tc
Tc
Basin
ID
Basin
ID
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Table 2: Time of Concentration – Shallow Flow
Table 3: Time of Concentration Calculations Concentrated Flow and Total Tc
Pre Development
L US Elev DS Elev S V
(ft)(ft)(ft)(ft/ft)(ft/s)(hr)(min)
1 200 4606.00 4604.81 0.006 0.55 0.10 6.1
2 275 4610.96 4607.03 0.014 0.70 0.11 6.5
3 127 4609.88 4607.00 0.023 1.00 0.04 2.1
Post Development
L US Elev DS Elev S V
(ft)(ft)(ft)(ft/ft)(ft/s)(hr)(min)
1 0 0.00 0.00 0.000 0.0 0.00 0.0
2 275 4610.09 4606.00 0.015 2.5 0.03 1.8
3 128 4609.58 4607.00 0.020 2.7 0.01 0.8
Shallow Flow
Tt(hr)=L
3600V
Time of Concentration Calculations
Tc
Tc
Shallow Flow
Shallow Concentrated Flow
Basin
ID
Basin
ID
Pre Development
Total
L US Elev DS Elev S Tc Tc
(ft)(ft)(ft)(ft/ft)n (min)(min)
1 0 0 0 0 0 0 21.8
2 0 0 0 0 0 0 12.8
3 0 0 0 0 0 0 15.5
Post Development
Total
L US Elev DS Elev S Tc Tc
(ft)(ft)(ft)(ft/ft)n (min)(min)
1 209 4605 4604 0.005 0.018 12.13 14.5
2 0 0 0 0 0 0 6.7
3 0 0 0 0 0 0 9.5
Concetrated Flow
V=
Time of Concentration Calculations
Totals
Concentrated Flow
Concentrated Flow
1.49R2/3S1/2
n
Basin
ID
Basin
ID
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Table 4: Weighted C Calculations
Table 5: Runoff Calculations
Area Area Site C Weighted
Type (ft2)(ac.)%Factor C
Pond 1
Hardscape 43,121 0.99 66.3%0.95 0.63
Landscape 21,958 0.50 33.7%0.20 0.07
Gravel 0 0 0.50 0.00
Total 65,079 1.49 0.70
Pond 2
Hardscape 34,348 0.79 58.9%0.95 0.56
Landscape 24,008 0.55 41.1%0.20 0.08
Gravel 0 0 0.50 0.00
Total 58,356 1.34 0.64
Pond 3
Hardscape 14,857 0.34 36.0%0.95 0.34
Landscape 26,453 0.61 64.0%0.20 0.13
Gravel 0 0 0.50 0.00
Total 41,310 0.95 0.47
Weighted C
Weighted C Calculations
Weighted C
Weighted C
Area Tc I2 Q2 I10 Q10 I100 Q100
Basin ID (ac.)*C (min)(in/hr)(cfs)(in/hr)(cfs)(in/hr)(cfs)
1 1.49 0.20 21.8 0.94 0.3 1.74 0.5 2.74 0.8
2 1.34 0.20 12.8 1.37 0.4 2.53 0.7 3.98 1.1
3 0.95 0.20 15.5 1.21 0.2 2.25 0.4 3.53 0.7
Area Weighted Tc I2 Q2 I10 Q10 I100 Q100
Basin ID (ac.)C (min)(in/hr)(cfs)(in/hr)(cfs)(in/hr)(cfs)
1 1.49 0.70 14.5 1.27 0.0 2.34 2.4 3.69 3.8
2 1.34 0.64 6.7 1.89 0.0 3.51 3.0 5.53 4.7
3 0.95 0.47 9.5 1.59 0.0 2.93 1.3 4.61 2.1
Runoff Calculations
Pre Development Peak Flows
Post Development Peak Flows
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Stormwater Retention Calculations
The City of Bozeman requires that the first 0.5 inches of rainfall to be captured. The proposed retention
ponds have been sized to store the first 0.5 inches of rainfall from a 24-hour storm event. The volume
of the first 0.5 inches of rainfall was computed using the Runoff Reduction Volume method from the
Montana Post-Construction Stormwater BMP Manual, Equation 3-1. In addition to the first 0.5 inch of
rainfall to be captured, the City of Bozeman requires retention ponds to be sized to hold the 10-year, 2-
hour storm. A third computation was completed using the Montana DEQ Appendix C: Standard Storm
Drainage Plan spreadsheet. The highest calculated volume was utilized to size the three ponds.
Table 6: Pond 1 Runoff Reduction Volume
Table 7: Pond 1 Retention Volume
Area P RRV
(ac.)(in.)Rv I (ac-ft)ft3
1.49 0.5 1.096 0.663 0.07 2,965
RRV=PRvA
12
RRV =Runoff Reduction Volume (acre-ft)
P =Water quality rainfall depth (0.5 inches)
Rv =Dimensionless runoff coefficient, Rv=0.5+0.9(I)
I =
A =Site Drainage Area (acres)
Pond 1 Runoff Reduction Volume
(First 0.5 inches of rainfall)
Precent Impervious cover draining to the facility to
a decimal form
Area I*Q V
(ac.)C (in/hr)(cfs)(ft3)
1.49 0.70 0.41 0.4 3,066
*City of Bozeman requires 10-yr, 2-hr storm
Q=CIA C =Weighted C Factor
V=7200Q I =0.41 in/hr (10-year 2-hr storm)
A =Area (acres)
Q =runoff (cfs)
V =Volume (ft3)
Retention Volume
10-yr, 2-hr storm
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Table 8:Pond 2 Runoff Reduction Volume
Table 9: Pond 2 Retention Volume
Area P RRV
(ac.)(in.)Rv I (ac-ft)ft3
1.34 0.5 1.030 0.589 0.06 2,504
RRV=PRvA
12
RRV =Runoff Reduction Volume (acre-ft)
P =Water quality rainfall depth (0.5 inches)
Rv =Dimensionless runoff coefficient, Rv=0.5+0.9(I)
I =
A =Site Drainage Area (acres)
Pond 2 Runoff Reduction Volume
(First 0.5 inches of rainfall)
Precent Impervious cover draining to the facility to
a decimal form
Area I*Q V
(ac.)C (in/hr)(cfs)(ft3)
1.34 0.64 0.41 0.4 2,537
*City of Bozeman requires 10-yr, 2-hr storm
Q=CIA C =Weighted C Factor
V=7200Q I =0.41 in/hr (10-year 2-hr storm)
A =Area (acres)
Q =runoff (cfs)
V =Volume (ft3)
Retention Volume
10-yr, 2-hr storm
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Table 10: Pond 3 Runoff Reduction Volume
Table 11: Pond 3 Retention Volume
Area P RRV
(ac.)(in.)Rv I (ac-ft)ft3
0.95 0.5 0.824 0.360 0.03 1,420
RRV=PRvA
12
RRV =Runoff Reduction Volume (acre-ft)
P =Water quality rainfall depth (0.5 inches)
Rv =Dimensionless runoff coefficient, Rv=0.5+0.9(I)
I =
A =Site Drainage Area (acres)
Pond 3 Runoff Reduction Volume
(First 0.5 inches of rainfall)
Precent Impervious cover draining to the facility to
a decimal form
Area I*Q V
(ac.)C (in/hr)(cfs)(ft3)
0.95 0.47 0.41 0.2 1,317
*City of Bozeman requires 10-yr, 2-hr storm
Q=CIA C =Weighted C Factor
V=7200Q I =0.41 in/hr (10-year 2-hr storm)
A =Area (acres)
Q =runoff (cfs)
V =Volume (ft3)
Retention Volume
10-yr, 2-hr storm
November 2024
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DEC Job No. 10875
Table 12: Pond 1 Appendix C DEQ Volume
Sudivision Name
EQ#
County Gallatin County 0.9
Location NW corner IH90 and Nelson Rd.0.8
Lot/Area No.POND 1 0.1
0.2
Precipitation Data Q=C*i*A
2-year, Tc 0.94 inches/hour TC = Time of Concentration
2-year, 24-hour 1.13 inches
10-year, Tc 1.74 inches/hour
100-year, Tc 2.74 inches/hour
100-year, 24-hour 3.71 inches
Total Area/Lot Size 1.494 acres =65078.64 ft2
Initial Stormwater Facility Volume (0.5" x Impervious Area) =1797 ft3
Paved/House Area 0 acres ft2 Q=0.0 ft3/sec V=0 ft3 Q=0.0 ft3/sec Q=0.0 ft3/sec V=0 ft3
Gravel Area 0 acres ft2 Q=0.0 ft3/sec V=0 ft3 Q=0.0 ft3/sec Q=0.0 ft3/sec V=0 ft3
Lawn/Landscaping 0 acres ft2 Q=0.0 ft3/sec V=0 ft3 Q=0.0 ft3/sec Q=0.0 ft3/sec V=0 ft3
Unimproved Area 1.494 acres 65078.64 ft2 Q=0.3 ft3/sec V=1,226 ft3 Q=0.5 ft3/sec Q=0.8 ft3/sec V=4,024 ft3
Total 1.494 acres 65078.64 ft2 QTotal=0.3 ft3/sec VTotal=1,226 ft3 QTotal=0.5 ft3/sec QTotal=0.8 ft3/sec VTotal=4,024 ft3
Paved/House Area 0.98992195 acres 43,121 ft2 Q=0.8 ft3/sec V=3,655 ft3 Q=1.6 ft3/sec Q=2.5 ft3/sec V=11,998 ft3
Gravel Area 0 acres 0 ft2 Q=0.0 ft3/sec V=0 ft3 Q=0.0 ft3/sec Q=0.0 ft3/sec V=0 ft3
Lawn/Landscaping 0.50407805 acres 21,958 ft2 Q=0.0 ft3/sec V=207 ft3 Q=0.1 ft3/sec Q=0.1 ft3/sec V=679 ft3
Unimproved Area 0 acres 0 ft2 Q=0.0 ft3/sec V=0 ft3 Q=0.0 ft3/sec Q=0.0 ft3/sec V=0 ft3
Total 1.494 acres 65078.64 ft2 QTotal=0.9 ft3/sec VTotal=3,861 ft3 QTotal=1.7 ft3/sec QTotal=2.6 ft3/sec VTotal=12,677 ft3
ΔQ=0.6 ft3/sec ΔV=2,636 ft3 ΔQ=1.1 ft3/sec ΔQ=1.8 ft3/sec ΔV=8,653 ft3
2636 ft3
Lawn/landscaping
Appendix C: Standard Storm Drainage Plan
Nelson Meadows - Lot 21 & 22
Rational Method Co-Efficients (C)
Paved/hard surfaces
Gravel surfaces
(volume)
Unimproved areas
2-year, Tc 2-year, 24-hour 10-year, Tc 100-year, Tc 100-year, 24-hour
Pre-Development Characteristics (flow rate)(volume)(flow rate)(flow rate)
2-year, Tc 2-year, 24-hour 10-year, Tc 100-year, Tc 100-year, 24-hour
(volume)
Runoff Flow/Volume Change
Required Minimum Facility Volume:
Post-Development Characteristics (flow rate)volume)(flow rate)(flow rate)
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Table 13: Pond 2 Appendix C DEQ Volume
Sudivision Name
EQ#
County Gallatin County 0.9
Location NW corner IH90 and Nelson Rd.0.8
Lot/Area No.1 - POND 2 0.1
0.2
Precipitation Data Q=C*i*A
2-year, Tc 1.37 inches/hour TC = Time of Concentration
2-year, 24-hour 1.13 inches
10-year, Tc 2.53 inches/hour
100-year, Tc 3.98 inches/hour
100-year, 24-hour 3.71 inches
Total Area/Lot Size 1.34 acres =58370.4 ft2
Initial Stormwater Facility Volume (0.5" x Impervious Area) =1431 ft3
Paved/House Area 0 acres ft2 Q=0.0 ft3/sec V=0 ft3 Q=0.0 ft3/sec Q=0.0 ft3/sec V=0 ft3
Gravel Area 0 acres ft2 Q=0.0 ft3/sec V=0 ft3 Q=0.0 ft3/sec Q=0.0 ft3/sec V=0 ft3
Lawn/Landscaping 0 acres ft2 Q=0.0 ft3/sec V=0 ft3 Q=0.0 ft3/sec Q=0.0 ft3/sec V=0 ft3
Unimproved Area 1.34 acres 58370.4 ft2 Q=0.4 ft3/sec V=1,099 ft3 Q=0.7 ft3/sec Q=1.1 ft3/sec V=3,609 ft3
Total 1.34 acres 58370.4 ft2 QTotal=0.4 ft3/sec VTotal=1,099 ft3 QTotal=0.7 ft3/sec QTotal=1.1 ft3/sec VTotal=3,609 ft3
Paved/House Area 0.78852158 acres 34,348 ft2 Q=1.0 ft3/sec V=2,911 ft3 Q=1.8 ft3/sec Q=2.8 ft3/sec V=9,557 ft3
Gravel Area 0 acres 0 ft2 Q=0.0 ft3/sec V=0 ft3 Q=0.0 ft3/sec Q=0.0 ft3/sec V=0 ft3
Lawn/Landscaping 0.55147842 acres 24,022 ft2 Q=0.1 ft3/sec V=226 ft3 Q=0.1 ft3/sec Q=0.2 ft3/sec V=743 ft3
Unimproved Area 0 acres 0 ft2 Q=0.0 ft3/sec V=0 ft3 Q=0.0 ft3/sec Q=0.0 ft3/sec V=0 ft3
Total 1.34 acres 58370.4 ft2 QTotal=1.1 ft3/sec VTotal=3,137 ft3 QTotal=2.0 ft3/sec QTotal=3.1 ft3/sec VTotal=10,300 ft3
ΔQ=0.7 ft3/sec ΔV=2,038 ft3 ΔQ=1.3 ft3/sec ΔQ=2.0 ft3/sec ΔV=6,691 ft3
2038 ft3
(volume)
Runoff Flow/Volume Change
Required Minimum Facility Volume:
Post-Development Characteristics (flow rate)volume)(flow rate)(flow rate)
2-year, Tc 2-year, 24-hour 10-year, Tc 100-year, Tc 100-year, 24-hour
Pre-Development Characteristics (flow rate)(volume)(flow rate)(flow rate)(volume)
Unimproved areas
2-year, Tc 2-year, 24-hour 10-year, Tc 100-year, Tc 100-year, 24-hour
Lawn/landscaping
Appendix C: Standard Storm Drainage Plan
Nelson Meadows - Lot 21 & 22
Rational Method Co-Efficients (C)
Paved/hard surfaces
Gravel surfaces
December 2024
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Table 14: Pond 3 Appendix C DEQ Volume
Sudivision Name
EQ#
County Gallatin County 0.9
Location NW corner IH90 and Nelson Rd.0.8
Lot/Area No.1 - POND 3 0.1
0.2
Precipitation Data Q=C*i*A
2-year, Tc 1.21 inches/hour TC = Time of Concentration
2-year, 24-hour 1.13 inches
10-year, Tc 2.25 inches/hour
100-year, Tc 3.53 inches/hour
100-year, 24-hour 3.71 inches
Total Area/Lot Size 0.95 acres =41382 ft2
Initial Stormwater Facility Volume (0.5" x Impervious Area) =619 ft3
Paved/House Area 0 acres ft2 Q=0.0 ft3/sec V=0 ft3 Q=0.0 ft3/sec Q=0.0 ft3/sec V=0 ft3
Gravel Area 0 acres ft2 Q=0.0 ft3/sec V=0 ft3 Q=0.0 ft3/sec Q=0.0 ft3/sec V=0 ft3
Lawn/Landscaping 0 acres ft2 Q=0.0 ft3/sec V=0 ft3 Q=0.0 ft3/sec Q=0.0 ft3/sec V=0 ft3
Unimproved Area 0.95 acres 41382 ft2 Q=0.2 ft3/sec V=779 ft3 Q=0.4 ft3/sec Q=0.7 ft3/sec V=2,559 ft3
Total 0.95 acres 41382 ft2 QTotal=0.2 ft3/sec VTotal=779 ft3 QTotal=0.4 ft3/sec QTotal=0.7 ft3/sec VTotal=2,559 ft3
Paved/House Area 0.34106979 acres 14,857 ft2 Q=0.4 ft3/sec V=1,259 ft3 Q=0.7 ft3/sec Q=1.1 ft3/sec V=4,134 ft3
Gravel Area 0 acres 0 ft2 Q=0.0 ft3/sec V=0 ft3 Q=0.0 ft3/sec Q=0.0 ft3/sec V=0 ft3
Lawn/Landscaping 0.60893021 acres 26,525 ft2 Q=0.1 ft3/sec V=250 ft3 Q=0.1 ft3/sec Q=0.2 ft3/sec V=820 ft3
Unimproved Area 0 acres 0 ft2 Q=0.0 ft3/sec V=0 ft3 Q=0.0 ft3/sec Q=0.0 ft3/sec V=0 ft3
Total 0.95 acres 41382 ft2 QTotal=0.4 ft3/sec VTotal=1,509 ft3 QTotal=0.8 ft3/sec QTotal=1.3 ft3/sec VTotal=4,954 ft3
ΔQ=0.2 ft3/sec ΔV=730 ft3 ΔQ=0.4 ft3/sec ΔQ=0.6 ft3/sec ΔV=2,395 ft3
729.5 ft3
(volume)
Runoff Flow/Volume Change
Required Minimum Facility Volume:
Post-Development Characteristics (flow rate)volume)(flow rate)(flow rate)
2-year, Tc 2-year, 24-hour 10-year, Tc 100-year, Tc 100-year, 24-hour
Pre-Development Characteristics (flow rate)(volume)(flow rate)(flow rate)(volume)
Unimproved areas
2-year, Tc 2-year, 24-hour 10-year, Tc 100-year, Tc 100-year, 24-hour
Lawn/landscaping
Appendix C: Standard Storm Drainage Plan
Nelson Meadows - Lot 21 & 22
Rational Method Co-Efficients (C)
Paved/hard surfaces
Gravel surfaces
November 2024
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DEC Job No. 10875
Table 15: Pond Volume Calculassions
GROUNDWATER AND SOILS INFORMATION
The National Resource Conservation Service (NRCS) classifies the soil type on site as Blackdog silt loam (50B).
The soil is in hydrologic soil group C and made up of predominately silts and loams that are well drained.
Groundwater levels were observed by Morrison-Maierle in 2018 between April and August as detailed in the
Comprehensive Drainage Plan for Nelson Meadows (Morrison Maierle, March 2019). The monitoring well
located on site is shown in Figure 4 (Summary of Ground water Depth Observations) in the Morrison Maierle
report. The minimum depth below the ground elevation on the site is more than feet as shown in Figure 5
(Groundwater Observation Well Locations) in the Morrison Maierle report. The approximate bottom of the
proposed retention pond will be 2 to 4 feet below existing grade and above the groundwater elevation.
Elev Area
Volume
Provided
Runoff
Reduction
Volume
Retention
Volume
Appendix C
DEQ Volume
(ft)(ft2)(ft3)(ft3)(ft3)(ft3)
4602 1,689 0
4603 2,409 2,049
4604 3,230 4,869 2,965 3,066 2,636
Elev Area
Volume
Provided
Runoff
Reduction
Volume
Retention
Volume
Appendix C
DEQ Volume
(ft)(ft2)(ft3)(ft3)(ft3)(ft3)
4605 2,478 0
4606 3,294 2,886 2,504 2,537 2,038
Elev Area
Volume
Provided
Runoff
Reduction
Volume
Retention
Volume
Appendix C
DEQ Volume
(ft)(ft2)(ft3)(ft3)(ft3)(ft3)
4607 1,505
4608 2,210 1,858 1,420 1,314 730
Required Volume
Pond 1 Volume Calculation
Pond 2 Volume Calculation
Pond 3 Volume Calculation
Pond Volume Calculations
Required Volume
Required Volume
December 2024
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Figure 3: NRCS Soils Map
December 2024
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DEC · 5300 Town & Country Boulevard, Suite 150 · Frisco, Texas 75034 · 469-850-0060
Figure 4: Groundwater Depth Comprehensive Drainage Plan for Nelson Meadows
(Morrison Maierle, March 2019)
December 2024
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DEC · 5300 Town & Country Boulevard, Suite 150 · Frisco, Texas 75034 · 469-850-0060
Figure 5: Groundwater Monitor Wells - Comprehensive Drainage Plan for Nelson Meadows
(Morrison Maierle, March 2019)
SITE
December 2024
Storm Drainage Report – Exception Healthcare Bozeman
DEC Job No. 10875
18
DEC · 5300 Town & Country Boulevard, Suite 150 · Frisco, Texas 75034 · 469-850-0060
CONCLUSION
The storm water management plan for the proposed development will adequately handle the storm events in accordance
with the local and state requirements. Adequate stormwater storage will be provided. The development will not have
adverse impacts to the surrounding properties.
December 2024
Storm Drainage Report – Exception Healthcare Bozeman
DEC Job No. 10875
19
DEC · 5300 Town & Country Boulevard, Suite 150 · Frisco, Texas 75034 · 469-850-0060
APPENDIX A – DRAINAGE AREA EXHIBIT
November 2024
Storm Drainage Report – Exception Healthcare Bozeman
DEC Job No. 10875