41146 Elm Street| Ste G | Murrieta, CA 92562
t: 951.698.1830 | e: [email protected]
PROUDLY SERVING THE INLAND EMPIRE FOR OVER 40 YEARS
May 13, 2021
City of Murrieta
Re: RP-2020-2236
This letter is intended to serve as the complete hydrology report as requested per the comment letter.
Introduction
Inland Empire Survey & Engineering, Inc. (IESE) was asked to complete a hydrology report for the proposed Uhaul development on Los Alamos Road in the City of Murrieta, CA. This hydrology analysis is intended to clearly demonstrate how the runoff generated from a 100-year storm event will be handled by the proposed development and where the overflow will exit the site.
Methodology
To evaluate the unit hydrograph for the project site, we utilized the “ Hydraflow Hydrographs” plugin for AutoCAD Civil 3D. The plugin uses either the SCS or Rational method for evaluating the unit hydrograph for the 2, 10, and 100 year storm return periods. Additionally, the National Ocean ic and Atmosphe ric Association (NOAA) Atlas 14 point -frequency data server (PFDS) to get a ccurate, localized rainfall data based on the latitude-longitude of the project.
Results
The post-development, 100-year hydrograph for the project was evaluated using the referenced plugin.
Per the report, the 100 -year runoff for the project site will be approximately 0.726 cubic feet per second (cfs). See Appendix ‘B’ for hydrograph report.
The proposed 4 -foot wide, 6 -inch deep overflow drain s located in the northeasterly and north westerly corners of the project site were analyzed to ensure that the 100-year runoff would be able to pass through the drain s effectively. The overflow drain s pass the 100 -year runoff at a depth just over 1.5 -inches.
Therefore, the drain has more than enough capacity to accept and handle the 100-year runoff effectively.
Discussion/Summary
The project site has been designed appropriately to convey and discharge the 100-year runoff.
Sincerely,
Inland Empire Survey & Engineering, Inc.
Alex R. Paulsen, PE
Project Engineer
PROUDLY SERVING THE INLAND EMPIRE FOR OVER 40 YEARS
APPENDIX A – NOAA ATLAS 14 RAINFALL DATA
NOAA Atlas 14, Volume 6, Version 2
Location name: Murrieta, California, USA*
Latitude: 33.5564°, Longitude: -117.2035°
Elevation: 1110.26 ft**
* source: ESRI Maps
** source: USGS
POINT PRECIPITATION FREQUENCY ESTIMATES
Sanja Perica, Sarah Dietz, Sarah Heim, Lillian Hiner, Kazungu Maitaria, Deborah Martin, Sandra Pavlovic, Ishani Roy, Carl Trypaluk, Dale Unruh, Fenglin Yan, Michael Y ekta, Tan Zhao, Geoffrey Bonnin, Daniel Brewer, Li-Chuan Chen, Tye Parzybok, John Yarchoan
NOAA, National Weather Service, Silver Spring, Maryland PF_tabular | PF_graphical | Maps_&_aerials
PF tabular
PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches/hour)1 Duration Average recurrence interval (years)
1 2 5 10 25 50 100 200 500 1000
5-min 1.38
(1.15-1.66)
1.82 (1.54-2.20)
2.44 (2.04-2.95)
2.96 (2.45-3.61)
3.70 (2.95-4.67)
4.28 (3.35-5.53)
4.90 (3.73-6.49)
5.56 (4.10-7.58)
6.48 (4.58-9.24)
7.22 (4.93-10.7)
10-min 0.990
(0.828-1.19)
1.31 (1.10-1.58)
1.75 (1.46-2.11)
2.12 (1.76-2.59)
2.65 (2.12-3.34)
3.07 (2.40-3.96)
3.51 (2.68-4.66)
3.98 (2.95-5.44)
4.64 (3.29-6.62)
5.17 (3.53-7.66)
15-min 0.796
(0.668-0.956)
1.06 (0.884-1.27)
1.41 (1.18-1.70)
1.71 (1.42-2.08)
2.14 (1.71-2.70)
2.47 (1.94-3.20)
2.83 (2.16-3.75)
3.21 (2.37-4.38)
3.74 (2.65-5.34)
4.17 (2.85-6.18)
30-min 0.618
(0.518-0.744)
0.820
(0.686-0.986)
1.09 (0.914-1.32)
1.33 (1.10-1.62)
1.66 (1.32-2.09)
1.92 (1.50-2.48)
2.20 (1.67-2.91)
2.49 (1.84-3.40)
2.90 (2.06-4.14)
3.24 (2.21-4.79)
60-min 0.469
(0.394-0.564)
0.622
(0.521-0.749)
0.831
(0.695-1.00)
1.01 (0.835-1.23)
1.26 (1.00-1.59)
1.46 (1.14-1.88)
1.67 (1.27-2.21)
1.89 (1.40-2.58)
2.21 (1.56-3.15)
2.46 (1.68-3.64)
2-hr 0.344
(0.288-0.414)
0.452
(0.378-0.544)
0.597
(0.499-0.722)
0.718
(0.596-0.876)
0.888
(0.710-1.12)
1.02 (0.800-1.32)
1.16 (0.886-1.54)
1.31 (0.968-1.79)
1.51 (1.07-2.16)
1.68 (1.14-2.48)
3-hr 0.286
(0.240-0.344)
0.374
(0.314-0.451)
0.493
(0.412-0.595)
0.591
(0.490-0.721)
0.729
(0.583-0.920)
0.837
(0.654-1.08)
0.949
(0.723-1.26)
1.07 (0.789-1.46)
1.23 (0.870-1.75)
1.36 (0.926-2.01)
6-hr 0.205
(0.172-0.246)
0.268
(0.224-0.322)
0.352
(0.294-0.425)
0.421
(0.349-0.513)
0.517
(0.413-0.653)
0.592
(0.463-0.765)
0.669
(0.510-0.887)
0.749
(0.554-1.02)
0.860
(0.609-1.23)
0.947
(0.646-1.40)
12-hr 0.135
(0.113-0.162)
0.178
(0.149-0.214)
0.234
(0.195-0.283)
0.280
(0.232-0.341)
0.344
(0.275-0.434)
0.393
(0.307-0.507)
0.443
(0.338-0.587)
0.495
(0.366-0.676)
0.566
(0.401-0.808)
0.622
(0.425-0.921)
24-hr 0.088
(0.077-0.101)
0.117
(0.103-0.135)
0.155
(0.137-0.180)
0.187
(0.163-0.218)
0.230
(0.195-0.277)
0.263
(0.218-0.324)
0.298
(0.241-0.375)
0.333
(0.263-0.431)
0.381
(0.289-0.513)
0.419
(0.307-0.583)
2-day 0.053
(0.046-0.061)
0.072
(0.063-0.083)
0.098
(0.086-0.113)
0.119
(0.104-0.139)
0.149
(0.126-0.180)
0.172
(0.143-0.212)
0.197
(0.159-0.248)
0.222
(0.175-0.288)
0.258
(0.195-0.347)
0.286
(0.210-0.398)
3-day 0.037
(0.033-0.043)
0.052
(0.046-0.060)
0.071
(0.063-0.082)
0.088
(0.077-0.102)
0.111
(0.094-0.134)
0.129
(0.107-0.159)
0.149
(0.121-0.187)
0.170
(0.134-0.219)
0.199
(0.151-0.268)
0.223
(0.163-0.310)
4-day 0.030
(0.027-0.035)
0.042
(0.037-0.049)
0.059
(0.052-0.068)
0.073
(0.064-0.085)
0.093
(0.078-0.112)
0.109
(0.090-0.134)
0.125
(0.102-0.158)
0.144
(0.113-0.186)
0.169
(0.128-0.228)
0.190
(0.140-0.265)
7-day 0.020
(0.018-0.023)
0.028
(0.025-0.033)
0.040
(0.035-0.046)
0.049
(0.043-0.057)
0.063
(0.053-0.076)
0.074
(0.061-0.091)
0.086
(0.070-0.108)
0.099
(0.078-0.128)
0.117
(0.089-0.158)
0.132
(0.097-0.184)
10-day 0.015
(0.013-0.017)
0.021
(0.019-0.025)
0.030
(0.027-0.035)
0.038
(0.033-0.044)
0.048
(0.041-0.058)
0.057
(0.047-0.070)
0.066
(0.054-0.083)
0.076
(0.060-0.099)
0.091
(0.069-0.122)
0.102
(0.075-0.143)
20-day 0.009
(0.008-0.011)
0.013
(0.012-0.016)
0.019
(0.017-0.022)
0.024
(0.021-0.028)
0.031
(0.026-0.037)
0.037
(0.031-0.045)
0.043
(0.035-0.054)
0.050
(0.039-0.065)
0.060
(0.045-0.081)
0.068
(0.050-0.095)
30-day 0.007
(0.006-0.008)
0.011
(0.009-0.012)
0.015
(0.013-0.018)
0.019
(0.017-0.022)
0.025
(0.021-0.030)
0.030
(0.025-0.036)
0.035
(0.028-0.044)
0.040
(0.032-0.052)
0.049
(0.037-0.065)
0.055
(0.041-0.077)
45-day 0.006
(0.005-0.007)
0.008
(0.007-0.010)
0.012
(0.010-0.014)
0.015
(0.013-0.018)
0.020
(0.017-0.024)
0.023
(0.019-0.029)
0.028
(0.022-0.035)
0.032
(0.025-0.042)
0.039
(0.029-0.052)
0.044
(0.032-0.062)
60-day 0.005
(0.004-0.006)
0.007
(0.006-0.008)
0.010
(0.009-0.012)
0.013
(0.011-0.015)
0.017
(0.014-0.020)
0.020
(0.017-0.025)
0.024
(0.019-0.030)
0.028
(0.022-0.036)
0.034
(0.025-0.045)
0.038
(0.028-0.053)
1 Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS).
Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values.
Please refer to NOAA Atlas 14 document for more information.
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US Department of Commerce
National Oceanic and Atmospheric Administration
National Weather Service
National Water Center
1325 East West Highway
Silver Spring, MD 20910
Questions?: [email protected]
Disclaimer
PROUDLY SERVING THE INLAND EMPIRE FOR OVER 40 YEARS
APPENDIX B – 100-YEAR UNIT HYDROGRAPH
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019.2 Thursday, 05 / 13 / 2021 Hyd. No. 1
20002 Uhaul
Hydrograph type = Rational Peak discharge = 0.726 cfs Storm frequency = 100 yrs Time to peak = 27 min
Time interval = 1 min Hyd. volume = 1,176 cuft
Drainage area = 1.130 ac Runoff coeff. = 0.28*
Intensity = 2.294 in/hr Tc by FAA = 27.00 min
IDF Curve = 20002 Uhaul.IDF Asc/Rec limb fact = 1/1
* Composite (Area/C) = [(0.250 x 0.90) + (0.880 x 0.10)] / 1.130 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50 52 54 Q (cfs)
0.00 0.00
0.10 0.10
0.20 0.20
0.30 0.30
0.40 0.40
0.50 0.50
0.60 0.60
0.70 0.70
0.80 0.80
0.90 0.90
1.00 1.00
Q (cfs)
Time (min)
20002 Uhaul
Hyd. No. 1 -- 100 Year
Hyd No. 1
PROUDLY SERVING THE INLAND EMPIRE FOR OVER 40 YEARS
APPENDIX C – OVERFLOW DRAIN HYDRAULICS
Weir Report
Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Friday, May 14 2021 Hydrololgy Report - 100-year overflow drain
Rectangular Weir
Crest = Sharp
Bottom Length (ft) = 4.00
Total Depth (ft) = 0.50
Calculations
Weir Coeff. Cw = 3.33
Compute by: Known Q
Known Q (cfs) = 0.73
Highlighted
Depth (ft) = 0.14
Q (cfs) = 0.726
Area (sqft) = 0.57
Velocity (ft/s) = 1.26
Top Width (ft) = 4.00
0 .5 1 1.5 2 2.5 3 3.5 4 4.5 5
Depth (ft) Depth (ft)Hydrololgy Report - 100-year overflow drain -0.50 -0.50
0.00 0.00
0.50 0.50
1.00 1.00
Length (ft)Weir W.S.