HomeMy WebLinkAbout01_20-822 DRAINAGE REPORT Addendum #2 FULLT:\20-822 Avila Ranch Earthwood PIPs\Civil\Drainage\_REPORT\_addendum #2\20-822 DRAINAGE REPORT Addendum #2.docx
TRACT 2943 EARTHWOOD PHASE II
DRAINAGE STUDY
– ADDENDUM 2 –
EARHTWOOD LANE, SAN LUIS OBISPO, CA
DATE: SEPTEMBER 27, 2021
141 South Elm Street | Arroyo Grande, CA 93420
Phone: (805) 489-1321 | Fax: (805) 489-6723
Prepared for: Mr. Michael Hodge
Job # 20-822
William Rebik, RCE 35,337
Exp. 09/30/2023
September 27, 2021 20-822 Tract 2943
ADDENDUM No. 2
141 South Elm Street • Arroyo Grande, CA, 93420 • Telephone 805.489.1321 • Fax 805.489.6723 • garingtaylor.com
R. James Garing, PE | Jeffrey J. Emrick, PE | Ronald G. Reilly, PE | William L. Rebik, PE, LS
Perry D. McBeth, PE | James A. Cooper, PE
Table of Contents
I. INTRODUCTION …………………………………………………………………………………………. 3
II. WEIR SIZE DETERMINATION ………………………………………………..……………….. 3
III. SUMMARY AND DISCUSSION………………………………………………………………………. 3
APPENDICIES
A. Revised Weir 4
B. Ernie Ball Basin W Spill Way No 3 6
C. Hydraflow 77’ Weir Report 8
D. Hydraflow 100’ Channel report 10
E. Addendum No 1 and Approved Drainage Report 12
September 27, 2021 20-822 Tract 2943
ADDENDUM No. 2
3
I. INTRODUCTION
This addendum is to address the revised weir for the Ernie Ball Basin. This Addendum no. 2 is to be
incorporated as final steps to the original drainage report titled “Tract 2943 Earthwood Phase II
Drainage Study” dated October 23, 2020, with final revision on 02/22/2021 and including Addendum
No. 1. Dated 2/24/2021 (Included in Appendix E. The revised calculations presented in this
Addendum #2 were executed using AutoDesk Hydraflow Express.
Originally the basin weir was designed along the tract boundary. Due to complication with that design
the project is going to revert to a weir at the historic location. Avila Ranch was directed to receive the
drainage as a condition of approval. The historic weir length was determined from current and past
topography to be approximately 40-45’ long. See the included exhibit in Appendix A “Revised Weir”
for the data used to determine the historic location.
II. WEIR SIZE DETERMINATION
From historic and current topographic surveys, it was determined that the overland escape for the
Ernie Ball basin would have drained to the south-east from the current basin location. Based on the
topographic data it is estimated that the weir was approximately 40-45’ long. To assure the historic
flow is not increased the project will install a 77’ trapezoidal shaped weir curb with 4:1 side slopes
and a flat sectional length of 69’. See Appendix B for the “Ernie Ball Basin W Spill Way NO. 3” for
weir information.
The weir will be constructed from an 18” deep flush curb with an invert elevation of 114.23’. It is
important to note that the inlets at Earthwood Lane (Sta 39+80 +/-) are set at 114.23’ which would
inhibit Earthwood Lanes flows from entering the basin when the WSE is at or above 114.23’. The
total out flow from the basin would be the existing Ernie Ball Lots 1 and 2 (DMA 1) development
producing a 100-year 10-minute maximum flow under 32 cfs as determined with the approved
drainage report (See Appendix B).
The flows overtopping the weir will exit the curb section with a depth of 0.32’ and a velocity of 1.46
ft/s. See Appendix C for the Hydraflow output report “Curb Weir L=-77 side slope 4:1”. The flows
will spread to 100’ at the property line by flowing over a compacted DG surface with an assumed n-
value of 0.030.
III. SUMMARY AND DISCUSSION
As described the proposed weir design will outlet flows at the historic location is a non-erosive
manner. The final depth of flow at weir in the historic location will be 0.32’ with a velocity of 1.46
ft/s and a volume of <32 cfs.
GARING, TAYLOR AND ASSOCIATES
TR 2943 EARTHWOOD LANE PHASE II
PAGE 4
Appendix “A”
Revised Weir
GARING, TAYLOR & ASSOCIATES, INC.
CIVIL ENGINEERS · SURVEYORS · PLANNERS
141 SOUTH ELM STREET · ARROYO GRANDE, CA 93420 · (805) 489-1321
GARING, TAYLOR AND ASSOCIATES
TR 2943 EARTHWOOD LANE PHASE II
PAGE 6
Appendix “B”
Ernie Ball Basin W Spill Way No 3
GARING, TAYLOR & ASSOCIATES, INC.
CIVIL ENGINEERS · SURVEYORS · PLANNERS
141 SOUTH ELM STREET · ARROYO GRANDE, CA 93420 · (805) 489-1321
WEIR CROSS SECTION
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GARING, TAYLOR AND ASSOCIATES
TR 2943 EARTHWOOD LANE PHASE II
PAGE 8
Appendix “C”
Hydraflow 77’ Weir Report
Weir Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Wednesday, Oct 6 2021
Curb Weir L=77' side slope 4:1
Rectangular Weir
Crest = Broad
Bottom Length (ft) = 69.00
Total Depth (ft) = 1.00
Calculations
Weir Coeff. Cw = 2.60
Compute by: Known Q
Known Q (cfs) = 32.00
Highlighted
Depth (ft) = 0.32
Q (cfs) = 32.00
Area (sqft) = 21.85
Velocity (ft/s) = 1.46
Top Width (ft) = 69.00
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80
Depth (ft)Depth (ft)Curb Weir L=77' side slope 4:1
-0.50 -0.50
0.00 0.00
0.50 0.50
1.00 1.00
1.50 1.50
2.00 2.00
Length (ft)Weir W.S.
GARING, TAYLOR AND ASSOCIATES
TR 2943 EARTHWOOD LANE PHASE II
PAGE 10
Appendix “D”
Hydraflow 100’ Channel Report
Channel Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Monday, Sep 27 2021
100' rect channel to PL/Tract Boundary
Rectangular
Bottom Width (ft) = 100.00
Total Depth (ft) = 1.00
Invert Elev (ft) = 114.23
Slope (%) = 6.00
N-Value = 0.030
Calculations
Compute by: Known Q
Known Q (cfs) = 32.00
Highlighted
Depth (ft) = 0.12
Q (cfs) = 32.00
Area (sqft) = 12.00
Velocity (ft/s) = 2.67
Wetted Perim (ft) = 100.24
Crit Depth, Yc (ft) = 0.15
Top Width (ft) = 100.00
EGL (ft) = 0.23
0 10 20 30 40 50 60 70 80 90 100 110 120
Elev (ft)Depth (ft)Section
113.50 -0.73
114.00 -0.23
114.50 0.27
115.00 0.77
115.50 1.27
116.00 1.77
Reach (ft)
GARING, TAYLOR AND ASSOCIATES
TR 2943 EARTHWOOD LANE PHASE II
PAGE 12
Appendix “E”
Addendum No 1 and Approved Drainage Report
T:\20-822 Avila Ranch Earthwood PIPs\Civil\Drainage\_REPORT\_addendum #1\20-822 DRAINAGE REPORT Addendum #1.docx
TRACT 2943 EARTHWOOD PHASE II
DRAINAGE STUDY
–ADDENDUM 1 –
EARHTWOOD LANE, SAN LUIS OBISPO, CA
DATE: FEBRUARY 24, 2021
141 South Elm Street | Arroyo Grande, CA 93420
Phone: (805) 489-1321 | Fax: (805) 489-6723
Prepared for: Mr. Michael Hodge
Job # 20-822
William Rebik, RCE 35,337
Exp. 09/30/2021
February 26, 2021 20-822 Tract 2943
DRAINAGE STUDY
141 South Elm Street • Arroyo Grande, CA, 93420 • Telephone 805.489.1321 • Fax 805.489.6723 • garingtaylor.com
R. James Garing, PE | Jeffrey J. Emrick, PE | Ronald G. Reilly, PE | William L. Rebik, PE, LS
Perry D. McBeth, PE | James A. Cooper, PE
Table of Contents
I. INTRODUCTION …………………………………………………………………………………………. 3
II. 85th PERCENTILE STORM EVENT ………………………………………………..……………….. 3
III. PEAK MANAGEMENT 2-100 YEAR………………………………………………………………. 4
IV. PIPE FLOW IN AND OUT …………………………………………………………………………….. 6
V. SUMMARY AND DISCUSSION………………………………………………………………………. 7
TABLES
1. Incremental Basin Volumes – Hydraflow Express
2. Outfall Pipe Properties – Hydraflow Express
3. Outfall Pipe Discharge Table – Hydraflow Express
4. Pre-Vs.-Post
5. 100-YEAR SCS Basin Hydroghraph Report – Hydraflow Express
5a. SCS 24-Hour Rainfall Totals
6. Tract 2943 100-Year Flows
7. Culvert Report – Hydraflow Express
APPENDICIES
A. 2-100-YEAR SCS Basin Hydroghraph Report – Hydraflow Express 8
B. Tract 2943 Earthwood Phase II Drainage Study 19
February 26, 2021 20-822 Tract 2943
DRAINAGE STUDY
3
I. INTRODUCTION
This addendum is to address the raising of the basin bottom and the additional calculations
performed using the SCS method to verify the modified basin will perform as intended. This
Addendum is to be incorporated as final steps to the original drainage report titled “Tract 2943
Earthwood Phase II Drainage Study” dated October 23, 2020 with final revision on 02/22/2021
(Included as Appedix B to this Addendum). The revised calculations presented in this Addendum #1
were executed using AutoDesk Hydraflow Express.
Originally the basin was lowered to accommodate the sag location at the track boundary. Through
the redesign process it was determined that the basin bottom could be adjusted to better match the
requirements of the site.
II. 85th PERCENTILE STORM EVENT
The basin will store the 85th Percentile Run-off volume (37442 CF) below the 110.6’ elevation. The
basin storage volume at the 110.6 elevation is 38,893 CF. TABLE 1 provides the complete revised
volumetric breakdown of the basin in incremental steps as report by Hydraflow.
TABLE 1 Incremental Basin Volumes – Hydraflow Express
The outfall pipe will be set at the 110.6’ elevation and run to the existing inlet at the sag location
near the tract boundary at an invert elevation of 108.47’. See TABLE 2 for specific pipe properties.
TABLE 2 Outfall Pipe Properties – Hydraflow Express
February 26, 2021 20-822 Tract 2943
DRAINAGE STUDY
4
The outflow will initially be much lower than the allowable pre-construction flow rate of 19 cfs and
would build to 14.19 cfs at an elevation of 114’. TABLE 3 provides the staged discharge available
from the 18” outfall pipe.
TABLE 3 Outfall Pipe Discharge Table – Hydraflow Express
III. PEAK MANAGEMENT 2-100 YEAR
The project will provide peak management for the 2 through 100-year storm events. The project
will mitigate the 100-year post construction run-off flow rates to a 10-year 10-minutes pre-
construction run-off rate.
The maximum flow off the site was determined as the 10-year 10-minute pre-construction run-off
rate of 19 cfs. The “Combined” site (12.64 AC) calculation is provided in TABLE 4 for the 2 through
100-year analysis.
"c" pre-con 0.42
"c" post-con 0.68
EB 1/2 PHASE I/II area (SF) 550621 12.64 area (AC)
minutes
2
year
in/hr
inflow
2yr post-
con CFS
inflow
10yr
post-
con
CFS
inflow
50yr
post-
con
CFS
inflow
100yr
post-con
CFS
outflow
2 yr pre
release
CFS
outflow
10 yr
pre
release
CFS
outflow
50 yr
pre
release
CFS
outflow
100 yr
pre
release
CFS
10 2.09 17.9 30.7 39.5 42.9 11.1 19.0 24.5 26.5
15 1.81 15.5 25.7 33.4 36.8 9.6 19.0 20.7 22.8
30 1.18 10.1 17.9 22.3 25.0 6.3 19.0 13.8 15.5
60 0.75 6.4 11.1 14.5 15.9 4.0 19.0 9.0 9.8
120 0.55 4.7 7.8 11.1 11.8 2.9 19.0 6.9 7.3
180 0.47 4.1 7.1 9.8 10.5 2.5 19.0 6.1 6.5
360 0.36 3.1 5.4 7.8 8.4 1.9 19.0 4.8 5.2
600 0.28 2.4 4.1 6.1 6.4 1.5 19.0 3.8 4.0
TABLE 4 Pre-Vs.-Post
The rational method Q=C*I*A was used to determine the run-off flow rates from post and pre-
construction conditions. These calculations are used to determine the curb inlet and initial pipe flow
requirements. The difference in flow rates from the 100-year event of varying durations and the 10-
year-10-minute event was calculated. The flow rates were then used to determine preliminary
storage volumes by multiplying the flow rate by the time of concentration in seconds. Complete
February 26, 2021 20-822 Tract 2943
DRAINAGE STUDY
5
calculations for the 2-100-year events are included in the original report. The original report is
included as Appendix B of this Addendum.
Additional calculations have now been performed on the basin using the SCS method in Hydraflow
Express. The CN number was determined by averaging Industrial Sites CN = 93 (Ernie Ball Lots 1 & 2)
and Commercial Sites CN = 95 (Earthwood Phase I & II) for a composite CN = 94. The 24-hour event
for the 2-100-year return periods were run through the basin to determine the maximum water
surface elevation (WSE). TABLE 5 provides the results of the 100-year analysis. TABLE 5a provides the
rainfall depth entered for each return period. The reports for the 2-100-year return periods are
included in Appendix A of this Addendum.
TABLE 5 100-YEAR SCS Basin Hydroghraph Report – Hydraflow Express
Return Fequency 2 - YR 10 - YR 25 - YR 50 - YR 100- YR
Total p (in) 2.57 4.01 4.85 5.48 6.11
TABLE 5a SCS 24-Hour Rainfall Totals
In the 100-year event the basin will fill to an elevation of 113.74’ and have a maximum outflow
through the 18” outfall pipe of 13.73 cfs. The basin overland escape will be set at the track
February 26, 2021 20-822 Tract 2943
DRAINAGE STUDY
6
boundary at the 114.0’ elevation with a basin rim elevation of 115.0’. The basin should never reach
the spill way as the maximum elevation in a 100-year event is 113.74’ as reported in TABLE 5.
IV. PIPE FLOW IN AND OUT
To determine the flows-in from Earthwood Lane DMAs 2-5 (Earthwood Lane Tract 2943 Phase I and
II) were combined and evaluated for the 100-year 10-minute storm event in the post-construction
conditions. TABLE 6 provides the results of the maximum 100-year flow. Calculations were performed
using the Rational Method: Q=C x I x A = 0.65 x I in/hr x 5.43 AC.
minutes 100 year
in/hr
inflow
100yr
post-con
CFS
10 5.00 17.6
15 4.29 15.1
30 2.91 10.3
60 1.85 6.5
120 1.38 4.9
180 1.22 4.3
360 0.98 3.5
600 0.75 2.6
TABLE 6 Tract 2943 100-Year Flows
The design flow to the basin from Earthwood Lane will be 17.7 CFS. Symmetric inlet configurations
will be installed on the East and West side of Earthwood Lane near the upstream property lines of
lots 14 and 17. 14.5’ of curb inlets will be installed. The East side of Earthwood Lane will drain across
Earthwood. The East side flow (DMA 2 and 5) for the 100-year event is 8.85 CFS. The Phase I and
Phase II East and West (DMA 2-5) flows will combine at the west inlet structure to be routed in the
24” pipe. The 24” pipe will be required to run 189’ at 0.53% from the West inlet (Invert 109.0’) at
Earthwood Lane to the Basin (Outfall Invert 108.0’). TABLE 7 provides the culvert report from
Hydraflow Express.
TABLE 7 Culvert Report – Hydraflow Express
February 26, 2021 20-822 Tract 2943
DRAINAGE STUDY
7
As reported in TABLE 7, the 24” pipe from Earthwood Lane to the basin will require 2.61’ of head to
push the flow. The invert of the 24” pipe at Earthwood Lane is 109.00’ + 2.61’ HW = 111.61 < Flow
line elevation of 114.06’ at curb inlet. OK
The 18” outfall pipe from the basin back to Earthwood Lane (at the tract boundary) will have the
flow capacities as identified in TABLE 1 and will reach a maximum flow rate of 13.73 cfs at a WSE of
113.74’ as shown in TABLE 5.
VI. SUMMARY AND DISCUSSION
The project will capture the 85th Percentile storm event for DMAs 1-5 and mitigate the post-
construction run-off rates to a 10-year 10-minute pre-construction run-off rate for the entire site.
As stated previously, DMA 6 will release without treatment into the sag inlets at the tract boundary.
DMA 6 is 1.01 AC and will have a post construction run-off rate of 3.28 cfs. (0.65 x 5 in/hr x 1.01 AC
= 3.28 cfs). The bypass flow from the inlets at lots 14 and 17 will also need to be collected at the
tract boundary. The total flow from Earthwood Phase I and II to be collected at the sag inlet at the
tract boundary should be 1.32 cfs x 2 inlets + 3.28 cfs = 5.92 cfs.
GARING, TAYLOR AND ASSOCIATES
TR 2943 EARTHWOOD LANE PHASE II
PAGE 8
Appendix “A”
2-100-YEAR SCS Basin Hydroghraph Report – Hydraflow Express
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Friday, 02 / 26 / 2021
Hyd. No. 2
Runoff Hydrograph
Hydrograph type = Reservoir Peak discharge = 13.73 cfs
Storm frequency = 100 yrs Time to peak = 10.27 hrs
Time interval = 2 min Hyd. volume = 216,632 cuft
Inflow hyd. No. = 1 - post construction Max. Elevation = 113.74 ft
Reservoir name = Ernie Ball Basin Max. Storage = 96,180 cuft
Storage Indication method used.
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28
Q (cfs)
0.00 0.00
10.00 10.00
20.00 20.00
30.00 30.00
40.00 40.00
50.00 50.00
Q (cfs)
Time (hrs)
Runoff Hydrograph
Hyd. No. 2 -- 100 Year
Hyd No. 2 Hyd No. 1 Total storage used = 96,180 cuft
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Friday, 02 / 26 / 2021
Hyd. No. 2
Runoff Hydrograph
Hydrograph type = Reservoir Peak discharge = 13.73 cfs
Storm frequency = 100 yrs Time to peak = 10.27 hrs
Time interval = 2 min Hyd. volume = 216,632 cuft
Inflow hyd. No. = 1 - post construction Max. Elevation = 113.74 ft
Reservoir name = Ernie Ball Basin Max. Storage = 96,180 cuft
Storage Indication method used.
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28
Elev (ft)
108.00 108.00
109.00 109.00
110.00 110.00
111.00 111.00
112.00 112.00
113.00 113.00
114.00 114.00
115.00 115.00
Elev (ft)
Time (hrs)
Runoff Hydrograph
Hyd. No. 2 -- 100 Year
1. Ernie Ball Basin
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Friday, 02 / 26 / 2021
Hyd. No. 2
Runoff Hydrograph
Hydrograph type = Reservoir Peak discharge = 12.91 cfs
Storm frequency = 50 yrs Time to peak = 10.27 hrs
Time interval = 2 min Hyd. volume = 187,128 cuft
Inflow hyd. No. = 1 - post construction Max. Elevation = 113.30 ft
Reservoir name = Ernie Ball Basin Max. Storage = 87,446 cuft
Storage Indication method used.
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28
Q (cfs)
0.00 0.00
10.00 10.00
20.00 20.00
30.00 30.00
40.00 40.00
50.00 50.00
Q (cfs)
Time (hrs)
Runoff Hydrograph
Hyd. No. 2 -- 50 Year
Hyd No. 2 Hyd No. 1 Total storage used = 87,446 cuft
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Friday, 02 / 26 / 2021
Hyd. No. 2
Runoff Hydrograph
Hydrograph type = Reservoir Peak discharge = 12.91 cfs
Storm frequency = 50 yrs Time to peak = 10.27 hrs
Time interval = 2 min Hyd. volume = 187,128 cuft
Inflow hyd. No. = 1 - post construction Max. Elevation = 113.30 ft
Reservoir name = Ernie Ball Basin Max. Storage = 87,446 cuft
Storage Indication method used.
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28
Elev (ft)
108.00 108.00
109.00 109.00
110.00 110.00
111.00 111.00
112.00 112.00
113.00 113.00
114.00 114.00
115.00 115.00
Elev (ft)
Time (hrs)
Runoff Hydrograph
Hyd. No. 2 -- 50 Year
1. Ernie Ball Basin
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Friday, 02 / 26 / 2021
Hyd. No. 2
Runoff Hydrograph
Hydrograph type = Reservoir Peak discharge = 11.53 cfs
Storm frequency = 25 yrs Time to peak = 10.27 hrs
Time interval = 2 min Hyd. volume = 157,697 cuft
Inflow hyd. No. = 1 - post construction Max. Elevation = 112.82 ft
Reservoir name = Ernie Ball Basin Max. Storage = 78,186 cuft
Storage Indication method used.
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28
Q (cfs)
0.00 0.00
10.00 10.00
20.00 20.00
30.00 30.00
40.00 40.00
Q (cfs)
Time (hrs)
Runoff Hydrograph
Hyd. No. 2 -- 25 Year
Hyd No. 2 Hyd No. 1 Total storage used = 78,186 cuft
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Friday, 02 / 26 / 2021
Hyd. No. 2
Runoff Hydrograph
Hydrograph type = Reservoir Peak discharge = 11.53 cfs
Storm frequency = 25 yrs Time to peak = 10.27 hrs
Time interval = 2 min Hyd. volume = 157,697 cuft
Inflow hyd. No. = 1 - post construction Max. Elevation = 112.82 ft
Reservoir name = Ernie Ball Basin Max. Storage = 78,186 cuft
Storage Indication method used.
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28
Elev (ft)
108.00 108.00
109.00 109.00
110.00 110.00
111.00 111.00
112.00 112.00
113.00 113.00
114.00 114.00
Elev (ft)
Time (hrs)
Runoff Hydrograph
Hyd. No. 2 -- 25 Year
1. Ernie Ball Basin
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Friday, 02 / 26 / 2021
Hyd. No. 2
Runoff Hydrograph
Hydrograph type = Reservoir Peak discharge = 8.296 cfs
Storm frequency = 10 yrs Time to peak = 10.27 hrs
Time interval = 2 min Hyd. volume = 118,618 cuft
Inflow hyd. No. = 1 - post construction Max. Elevation = 112.11 ft
Reservoir name = Ernie Ball Basin Max. Storage = 64,990 cuft
Storage Indication method used.
0 4 8 12 16 20 24 28 32
Q (cfs)
0.00 0.00
5.00 5.00
10.00 10.00
15.00 15.00
20.00 20.00
25.00 25.00
30.00 30.00
35.00 35.00
Q (cfs)
Time (hrs)
Runoff Hydrograph
Hyd. No. 2 -- 10 Year
Hyd No. 2 Hyd No. 1 Total storage used = 64,990 cuft
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Friday, 02 / 26 / 2021
Hyd. No. 2
Runoff Hydrograph
Hydrograph type = Reservoir Peak discharge = 8.296 cfs
Storm frequency = 10 yrs Time to peak = 10.27 hrs
Time interval = 2 min Hyd. volume = 118,618 cuft
Inflow hyd. No. = 1 - post construction Max. Elevation = 112.11 ft
Reservoir name = Ernie Ball Basin Max. Storage = 64,990 cuft
Storage Indication method used.
0 4 8 12 16 20 24 28 32
Elev (ft)
108.00 108.00
109.00 109.00
110.00 110.00
111.00 111.00
112.00 112.00
113.00 113.00
114.00 114.00
Elev (ft)
Time (hrs)
Runoff Hydrograph
Hyd. No. 2 -- 10 Year
1. Ernie Ball Basin
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Friday, 02 / 26 / 2021
Hyd. No. 2
Runoff Hydrograph
Hydrograph type = Reservoir Peak discharge = 1.635 cfs
Storm frequency = 2 yrs Time to peak = 12.20 hrs
Time interval = 2 min Hyd. volume = 52,475 cuft
Inflow hyd. No. = 1 - post construction Max. Elevation = 111.14 ft
Reservoir name = Ernie Ball Basin Max. Storage = 48,138 cuft
Storage Indication method used.
0 4 8 12 16 20 24 28 32 36 40
Q (cfs)
0.00 0.00
3.00 3.00
6.00 6.00
9.00 9.00
12.00 12.00
15.00 15.00
18.00 18.00
Q (cfs)
Time (hrs)
Runoff Hydrograph
Hyd. No. 2 -- 2 Year
Hyd No. 2 Hyd No. 1 Total storage used = 48,138 cuft
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020 Friday, 02 / 26 / 2021
Hyd. No. 2
Runoff Hydrograph
Hydrograph type = Reservoir Peak discharge = 1.635 cfs
Storm frequency = 2 yrs Time to peak = 12.20 hrs
Time interval = 2 min Hyd. volume = 52,475 cuft
Inflow hyd. No. = 1 - post construction Max. Elevation = 111.14 ft
Reservoir name = Ernie Ball Basin Max. Storage = 48,138 cuft
Storage Indication method used.
0 4 8 12 16 20 24 28 32 36 40
Elev (ft)
108.00 108.00
109.00 109.00
110.00 110.00
111.00 111.00
112.00 112.00
113.00 113.00
Elev (ft)
Time (hrs)
Runoff Hydrograph
Hyd. No. 2 -- 2 Year
1. Ernie Ball Basin
GARING, TAYLOR AND ASSOCIATES
TR 2943 EARTHWOOD LANE PHASE II
PAGE 19
Appendix “B”
Tract 2943 Earthwood Phase II Drainage Study
TRACT 2943 EARTHWOOD PHASE II
DRAINAGE STUDY
EARHTWOOD LANE, SAN LUIS OBISPO, CA
DATE: OCTOBER 23, 2020
REVISED 11/23/2020, 02/22/2021.
141 South Elm Street | Arroyo Grande, CA 93420
Phone: (805) 489-1321 | Fax: (805) 489-6723
Prepared for: Mr. Michael Hodge
Job # 20-822
William Rebik, RCE 35,337
Exp. 09/30/2021
February 22, 2021 20-822 Tract 2943
DRAINAGE STUDY
141 South Elm Street • Arroyo Grande, CA, 93420 • Telephone 805.489.1321 • Fax 805.489.6723 • garingtaylor.com
R. James Garing, PE | Jeffrey J. Emrick, PE | Ronald G. Reilly, PE | William L. Rebik, PE, LS
Perry D. McBeth, PE | James A. Cooper, PE
Table of Contents
I. INTRODUCTION …………………………………………………………………………………………. 3
II. 85th PERCENTILE STORM EVENT ………………………………………………..……………….. 4
III. PEAK MANAGEMENT 2-100 YEAR………………………………………………………………. 5
IV. PIPE FLOW IN AND OUT …………………………………………………………………………….. 6
V. GUTTER SPREAD AND DEPTH………………………………………………………………………. 9
VI. SUMMARY AND DISCUSSION………………………………………………………………………. 9
TABLES
1. 85th PERCENTILE STORM EVENT DATA
2. INCREMENTAL BASIN VOLUMES
3. PRE-Vs.-POST
4. 100-YEAR RUN-OFF VOLUMES
TRACT 2943 100-YEAR FLOW RATES
FIGURES
1. INLET STUCTURE ELEVATIONS
APPENDICIES
A. DMA EXHIBIT 10
B. PRE-Vs.-POST CALCULATIONS 12
C. BASIN -STORMDRAIN PLAN AND PROFILE EXHIBIT 18
D. INCREMENTAL BASIN VOLUME CHART 20
E. HYDRAFLOW REPORT INLET 2-YEAR 22
F. HYDRAFLOW REPORT INLET 100-YEAR 24
G. HYDRAFLOW REPORT 18” PIPE CROSSING EARTHWOOD 26
H. HYDRAFLOW REPORT 24” PIPE EARTHWOOD LANE TO BASIN 36
I. HYDRAFLOW REPORT 18” OUTFALL PIPE FROM BASIN 38
February 22, 2021 20-822 Tract 2943
DRAINAGE STUDY
3
I. INTRODUCTION
Tract 2943 is located near Los Osos Valley Road and South Higuera, off Suburban Road in the City of
San Luis Obispo. The Phase I portion of the tract has already been completed. The public
infrastructure for Phase II will be installed with the Avila Ranch development currently under
construction. The tentative tract map was approved with Resolution No. 10046 (2008 Series).
The Tract received entitlement with an approved drainage strategy, prepared by Keith Crowe, which
utilized a pumping system to help mitigate peak management from an onsite basin. The basin also
had historically provided fire water storage for the Ernie Ball lots prior to being annexed into the
City. The project has opted to negate the pump system and design a gravity treatment system. The
project with capture the 85th percentile storm event and provided peak management, as required
at the time of approval. This approach has been granted approval by the City’s Engineering and
Development Review Department. The project will meet the treatment requirement by utilizing
detention, infiltration and settling. The following discussions, narratives and calculations was
prepared for the revised drainage system.
The project watershed is approximately 13.67 acres with a gradual slope of 1-2% in a general north
to south direction. The project site will be divided into 6 Drainage Management Areas. See
APPENDIX A – “DMA Exhibit” for exact locations.
• DMA 1 - Ernie Ball Lots 1 & 2 - 314,113 SF (7.2 AC)
• DMA 2 - Earthwood Phase I West - 48,714 SF (1.15 AC)
• DMA 3 - Earthwood Phase I East – 49,885 SF (1.1 AC)
• DMA 4 – Earthwood Phase II West – 68,602 SF (1.57 AC)
• DMA 5 – Earthwood Phase II East – 69,307 SF (1.59 AC)
• DMA 6 – Earthwood Lots 14-17 & ROW – 44,100 SF (1.01 AC)
*DMA 6a – ROW Area ONLY – 9,168 SF (0.21 AC)
*Note Earthwood Tract 2943 total watershed area is 6.45 AC.
Earthwood East total area is 141,030 sf (3.23 AC)
Earthwood East -minus portion DMA 6 = 119,385 SF
Earthwood West total area is 140,328 (3.22 AC)
Earthwood West -minus portion DMA 6 = 117,553 SF
The project in located in the south portion of the City of San Luis Obispo, producing an average
rainfall depth of 22”-24” (WMP III Drainage Design Manual). The soil type is Class D with an
assumed infiltration rate of 0.25 in/hr.
The post-construction “c” values have been selected as “Neighborhood Commercial Soil Group D
<2%” = 0.65 for DMAs 2-6. For the Ernie Ball Lots 1 & 2, DMA 1, a run-off coefficient, “c”, of 0.7
was selected. For certain calculations, a composite run-off coefficient was developed to determine
combined flow and run-off volumes. The composite “c” value was calculated at 0.68.
The project will capture and retain the 85th percentile storm event, producing 1.2” of rain, across
the total site with DMA 6 bypassing the collection system. The ROW area in DMA 6 (DMA 6A - 0.21
AC) will be treated by a mechanized inlet filter system at the tract boundary inets. The ROW
treatment volume is 9,168 SF x 1.2”/12 x 0.9 = 825.12 cf. The 100 year flow rate for the ROW-
DMA 6A is determined from the rational method Q = CIA: 0.9 x 5 x 0.21 = 0.945 cfs. Lots 14-17 will
need to provide storage for the 85th percentile event at the time of development.
February 22, 2021 20-822 Tract 2943
DRAINAGE STUDY
4
The project will provide peak management for the total 13.67 acres for the 2-100-year storm
events for local regions producing 22”-24” of rain annually. The maximum post-construction run-
off rate in a 100-year event will be set at the 10-year pre-construction run-off rate of 19 cfs for the
entire site. The pre-construction run-off rate was determined from the Drainage Design Manual
using run-off coefficient of 0.42.
Earthwood Lane Phase I and II (DMAs 2-5) drainage will flow down Earthwood Lane to a series of
inlets (located near the upstream property lines of lots 14 and 17) where flow will be captured and
directed to the modified basin at the Ernie Ball site. The Ernie Ball site (DMA 1) will continue to
have the existing drainage courses direct run-off to the on-site basin.
The basin bottom will be set at 106.50. The basin will retain the run-off, from all sites, up to the
109.5 elevation (Basin Volume 41,269. See TABLE 2). The invert of the 18” outfall pipe from the
basin to Earthwood Lane will be set at 109.5. The outflow will initially be much lower than the 10-
year pre-con allowable outflow rate of 19 CFS and would reach the maximum outflow rate of 17
cfs with 5.55’ of headwater at an elevation of 115.05 (Basin Volume 142,252 CF. See TABLE 2). The
basin spill way safe over-flow will be set at 114.20’.
The time to fill the basin to the elevation of 114.2 takes 100-year flows approximately 210
minutes, at which time the 100-year storm event will be producing run-off at a rate of 10.1 CFS --
free release at less than the 10-year pre-construction run-off rate will be met. Additionally, the
basin should never reach the 114.20 elevation (Basin volume 125,605) as release starts occurring
at the 109.5 elevation (Basin volume 41,269).
II. 85th PERCENTILE STORM EVENT
The project will capture and retain the 85th percentile storm event producing 1.2” of rain across
DMAs 1-5. The volume of storage to retain the 85th event was determined using the composite run-
off coefficient of 0.68.
The following table provides the inputs and results for the 85th volume requirement.
85TH PERCENTILE 24-HOUR RAIN EVENT
TOATL
AREA SF
TOTAL
AREA AC
DEPTH
INCH
COMPOSITE
"c"
RUN-OFF
VOL. CF
550621 12.641 1.2 0.68 37442
TABLE 1
The basin will store the 85th Percentile Run-off volume (37442 CF) below the 109.25’ elevation.
The basin storage volume at the 109.25’ elevation is 37,526 CF. TABLE 2 provides the complete
volumetric breakdown of the basin in incremental steps. This table is also included as APPENDIX
D.
February 22, 2021 20-822 Tract 2943
DRAINAGE STUDY
5
TABLE 2 Incremental Basin Volumes
III. PEAK MANAGEMENT 2-100 YEAR
The project will provide peak management for the 2 through 100-year storm events. The project
will mitigate the 100-year post construction run-off flow rates to a 10-year 10-minutes pre-
construction run-off rate.
The maximum flow off the site was determined as the 10-year 10-minute pre-construction run-off
rate of 19 cfs. The “Combined” site calculation is provided in TABLE 3 for the 2 through 100-year
analysis.
minutes 2 year
in/hr
10
year
in/hr
50
year
in/hr
100
year
in/hr
inflow
2yr
post-
con
CFS
inflow
10yr
post-
con
CFS
inflow
50yr
post-
con
CFS
inflow
100yr
post-con
CFS
100yr Total
Vol CF
10 2.09 3.58 4.61 5.00 17.9 30.7 39.5 42.9 25731
15 1.81 2.99 3.90 4.29 15.5 25.7 33.4 36.8 33126
24.3 3.43 29.4 42893
30 1.18 2.09 2.60 2.91 10.1 17.9 22.3 25.0 44978
49.7 2.22 19.0 56661
60 0.75 1.30 1.69 1.85 6.4 11.1 14.5 15.9 57134
120 0.55 0.91 1.30 1.38 4.7 7.8 11.1 11.8 85094
180 0.47 0.83 1.14 1.22 4.1 7.1 9.8 10.5 113053
210.00 1.18 10.1 127640
360 0.36 0.63 0.91 0.98 3.1 5.4 7.8 8.4 182343
600 0.28 0.47 0.71 0.75 2.4 4.1 6.1 6.4 230968
TABLE 3 Pre-Vs.-Post
February 22, 2021 20-822 Tract 2943
DRAINAGE STUDY
6
The rational method Q=C*I*A was used to determine the run-off flow rates from post and pre-
construction conditions. The difference in flow rates from the 100-year event of varying durations
and the 10-year-10-minute event was calculated. The flow rates were used to determine the
required storage volumes by multiplying the flow rate by the time of concentration in seconds.
Complete calculations and analysis for each DMA and the “Combined” site are included as
APPENDIX B. TABLE 4 provides the time and storage volume (unadjusted) requirements in a 100-
year event to mitigate run-off to the 10-year pre-construction run-off rates.
minutes 100 year
in/hr
inflow 100yr
post-con CFS 100yr Total Vol CF
10 5.00 42.9 25731
15 4.29 36.8 33126
24.3 3.43 29.4 42893
30 2.91 25.0 44978
49.7 2.22 19.0 56661
60 1.85 15.9 57134
120 1.38 11.8 85094
180 1.22 10.5 113053
210.00 1.18 10.1 127640
360 0.98 8.4 182343
600 0.75 6.4 230968
TABLE 4 100-YEAR RUN-OFF VOLUMES
IV. PIPE FLOW IN AND OUT
To determine the flows-in from Earthwood Lane DMAs 2-5 (Earthwood Lane Tract 2943 Phase I and
II) were combined and evaluated for the 100-year 10-minute storm event in the post-construction
conditions. TABLE 5 provides the results of the maximum 100-year flow. Calculations were
performed using the Rational Method: Q=C x I x A = 0.65 x I in/hr x 5.43 AC.
minutes 100 year
in/hr
inflow
100yr
post-con
CFS
10 5.00 17.6
15 4.29 15.1
30 2.91 10.3
60 1.85 6.5
120 1.38 4.9
180 1.22 4.3
360 0.98 3.5
600 0.75 2.6
TABLE 5 Tract 2943 100-Year Flows
February 22, 2021 20-822 Tract 2943
DRAINAGE STUDY
7
The design flow to the basin from Earthwood Lane will be 17.6 CFS. Symmetric inlet configurations
will be installed on the East and West side of Earthwood Lane near the upstream property lines of
lots 14 and 17. 14.5’ of curb inlets will be installed. The East side of Earthwood Lane will drain across
Earthwood in an 18” pipe at 2.22%. The East side flow (DMA 2 and 5) for the 100-year event is 8.85
CFS. See APPENDIX G for Hydraflow Express Culvert Report for the 18” pipe crossing Earthwood
Lane. The Phase I and Phase II East and West (DMA 2-5) flows will combine at the west inlet structure
to be routed in the 24” pipe. The 24” pipe will be required to run 189’ at 0.53% from the West inlet
(Invert 108.0’) at Earthwood Lane to the Basin (Outfall Invert 107.0’). The 24” pipe will require 2.6’
of head to push 17.7 CFS to the basin. Please see APPENDIX H for Hydraflow Express Culvert Report
for the 24” pipe from Earthwood Lane to the Basin. FIGURE 1 provides the associated elevations for
the system. See APPENDIX C “Basin Stormdrain Plan & Profile” exhibit for complete design
elevations.
FIGURE 1
The basin will continue to fill with Combined flows from the Ernie Ball lots and Earthwood Lane
development. When the basin fills to elevation 114.20 (Tc approx. 210 minutes in the 100 year
storm) the headwater depth reaches 4.7’ and the 18” outfall pipe will be flowing at maximum
design outflow of 15.4 CFS (< 10-year 10-minute pre-construction flow rate). See APPENDIX I for
Hydraflow Express Culvert Report for the 18” pipe from the basin to Earthwood Lane. The report
provides the staged flows in the outfall pipe based on the WSE in the basin. At a Tc of 49.7 minutes
the 100-year post-construction run-off rates have diminished to less than the 10-year pre-
construction run-off rate of 19 cfs. In the 100-year storm event the system will be able to free
release run-off at 49.7 minutes with a flow rate of 19 CFS.
February 22, 2021 20-822 Tract 2943
DRAINAGE STUDY
8
minutes 100 year
in/hr
inflow 100yr
post-con CFS 100yr Total Vol CF
10 5.00 42.9 25731
15 4.29 36.8 33126
24.3 3.43 29.4 42893
30 2.91 25.0 44978
49.7 2.22 19.0 56661
60 1.85 15.9 57134
120 1.38 11.8 85094
180 1.22 10.5 113053
210.00 1.18 10.1 127640
360 0.98 8.4 182343
600 0.75 6.4 230968
TABLE 6 Combined Flows
The basin elevation at 49.7 minutes is just below 110.5’, See TABLE 2. Based on the report from
Hydraflow the 18” outfall pipe from the basin to Earthwood Lane will be flowing at approximately
4 cfs with 1.1’ of headwater. The headwater will continue to build with increasing outflow as
described in APPENDIX I. A Summary of the data reported by Hydraflow is provided in TABLE 7.
Hw/D D (ft) Hw (ft) Basin WSE Pipe Flow
cfs
3.7 1.5 5.6 115.1 17
3.36 1.5 5.0 114.5 16
3.13 1.5 4.7 114.2 15.4
2.98 1.5 4.5 114.0 15
2.01 1.5 3.0 112.5 14
1.83 1.5 2.7 112.2 13
1.66 1.5 2.5 112.0 12
1.51 1.5 2.3 111.8 11
1.36 1.5 2.0 111.5 10
1.24 1.5 1.9 111.4 9
1.14 1.5 1.7 111.2 8
1.03 1.5 1.5 111.0 7
0.93 1.5 1.4 110.9 6
0.83 1.5 1.2 110.7 5
0.72 1.5 1.1 110.6 4
0.61 1.5 0.9 110.4 3
0.49 1.5 0.7 110.2 2
0.33 1.5 0.5 110.0 1
0.16 1.5 0.2 109.7 0.25
TABLE 7 Hydraflow data for 18” outfall pipe
February 22, 2021 20-822 Tract 2943
DRAINAGE STUDY
9
V. GUTTER SPREAD AND DEPTH
The project was simulated in Hydraflow 2020 for the determination of gutter spread and depth.
See APPENDIX E and F for the complete Hydraflow output reports for the 2-year and 100-year
events, respectively, for the post-construction conditions. The spread in a two-year 10-minute
event is 7.95’ and the depth at the curb is 0.55’ with a 4” local depression. For the 100-year 10-
minute event the spread is 14.32’ and the depth of flow at the curb inlet is 0.68’ with a 4” local
depression. For the 100-year event there is a 1.32 cfs by-pass flow that will need to be captured
and treated with the ROW run-off from lots 14-17.
VI. SUMMARY AND DISCUSSION
The project will capture the 85th Percentile storm event for DMAs 1-5 and mitigate the post-
construction run-off rates to a 10-year 10-minute pre-construction run-off rate for the entire site.
As stated previously, DMA 6 will release without treatment into the sag inlets at the tract
boundary. DMA 6 is 1.01 AC and will have a post construction run-off rate of 3.28 cfs. (0.65 x 5
in/hr x 1.01 AC = 3.28 cfs). The bypass flow from the inlets at lots 14 and 17 will also need to be
collected at the tract boundary. The total flow from Earthwood Phase I and II to be collected at the
sag inlet at the tract boundary should be 1.32 cfs x 2 inlets + 3.28 cfs = 5.92 cfs.
GARING, TAYLOR AND ASSOCIATES
TR 2943 EARTHWOOD LANE PHASE II
PAGE 10
Appendix “A”
DMA EXHIBIT
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DRAINAGE MANAGEMENT AREA EXHIBIT
ERNIE BALL LOT 1, LOT 2, EARTHWOOD PHASE I AND PAHSE II
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GARING, TAYLOR AND ASSOCIATES
TR 2943 EARTHWOOD LANE PHASE II
PAGE 12
Appendix “B”
PRE-Vs-POST CALCULATIONS
141 South Elm Street • Arroyo Grande, CA, 93420 • Telephone 805.489.1321 • Fax 805.489.6723 • garingtaylor.com
Ronald G. Reilly, PE | Perry D McBeth, PE | James A. Cooper, PE, LS
William Rebik, PE, LS | Jeffrey J. Emrick, PE
Combined
"c" pre-con precon c 0.42
"c" post-con postcon c 0.68
EB 1/2 PHASE I/II area (SF) 550621 12.64 area (AC)
minutes 2 year in/hr 10 year in/hr 50 year in/hr 100 year in/hr inflow 2yr post-con
CFS
inflow 10yr
post-con CFS
inflow 50yr
post-con CFS
inflow 100yr post-
con CFS
outflow 10 yr
pre release
CFS
100yr Total Vol CF
10 2.09 3.58 4.61 5.00 17.9 30.7 39.5 42.9 19.0 25731
15 1.81 2.99 3.90 4.29 15.5 25.7 33.4 36.8 19.0 33126
24.3 3.43 29.4 19.0 42893
30 1.18 2.09 2.60 2.91 10.1 17.9 22.3 25.0 19.0 44978
49.7 2.22 19.0 19.0 56661
60 0.75 1.30 1.69 1.85 6.4 11.1 14.5 15.9 19.0 57134
120 0.55 0.91 1.30 1.38 4.7 7.8 11.1 11.8 19.0 85094
180 0.47 0.83 1.14 1.22 4.1 7.1 9.8 10.5 19.0 113053
210.00 1.18 10.1 19.0 127640
360 0.36 0.63 0.91 0.98 3.1 5.4 7.8 8.4 19.0 182343
600 0.28 0.47 0.71 0.75 2.4 4.1 6.1 6.4 19.0 230968
DMA 1 ERNIE BALL Lots 1 & 2
"c" pre-con precon c 0.42
"c" post-con postcon c 0.7
DMA 1 area (SF) 314113 7.2 area (AC)
minutes 2 year in/hr 10 year
in/hr
50 year
in/hr
100 year
in/hr
inflow 2yr
post-con CFS
inflow 10yr
post-con
CFS
inflow 50yr
post-con
CFS
inflow 100yr
post-con CFS
outflow 2
yr pre
release CFS
outflow 10
yr pre
release CFS
outflow 50
yr pre
release CFS
outflow
100 yr pre
release CFS
10 2.09 3.58 4.61 5.00 10.5 18.1 23.3 25.2 6.3 10.9 14.0 15.1
15 1.81 2.99 3.90 4.29 9.1 15.1 19.7 21.7 6.3 10.9 11.8 13.0
30 1.18 2.09 2.60 2.91 6.0 10.5 13.1 14.7 6.3 10.9 7.9 8.8
60 0.75 1.30 1.69 1.85 3.8 6.6 8.5 9.3 6.3 10.9 5.1 5.6
120 0.55 0.91 1.30 1.38 2.8 4.6 6.6 7.0 6.3 10.9 3.9 4.2
180 0.47 0.83 1.14 1.22 2.4 4.2 5.8 6.2 6.3 10.9 3.5 3.7
360 0.36 0.63 0.91 0.98 1.8 3.2 4.6 5.0 6.3 10.9 2.7 3.0
600 0.28 0.47 0.71 0.75 1.4 2.4 3.6 3.8 6.3 10.9 2.1 2.3
141 South Elm Street • Arroyo Grande, CA, 93420 • Telephone 805.489.1321 • Fax 805.489.6723 • garingtaylor.com
Ronald G. Reilly, PE | Perry D McBeth, PE | James A. Cooper, PE, LS
William Rebik, PE, LS | Jeffrey J. Emrick, PE
West
"c" pre-con precon c 0.42
"c" post-con postcon c 0.65
west area (SF) 117316 2.69 area (AC)
minutes 2 year in/hr 10 year
in/hr
50 year
in/hr
100 year
in/hr
inflow 2yr
post-con CFS
inflow
10yr post-
con CFS
inflow 50yr
post-con
CFS
inflow
100yr post-
con CFS
outflow 2
yr pre
release CFS
outflow 10
yr pre
release CFS
outflow 50
yr pre
release CFS
outflow 100
yr pre
release CFS
10 2.09 3.58 4.61 5.00 3.7 6.3 8.1 8.8 2.4 4.1 5.2 5.7
15 1.81 2.99 3.90 4.29 3.2 5.2 6.8 7.5 5.7 9.7 4.4 4.9
30 1.18 2.09 2.60 2.91 2.1 3.7 4.5 5.1 5.7 9.7 2.9 3.3
60 0.75 1.30 1.69 1.85 1.3 2.3 3.0 3.2 5.7 9.7 1.9 2.1
120 0.55 0.91 1.30 1.38 1.0 1.6 2.3 2.4 5.7 9.7 1.5 1.6
180 0.47 0.83 1.14 1.22 0.8 1.4 2.0 2.1 5.7 9.7 1.3 1.4
360 0.36 0.63 0.91 0.98 0.6 1.1 1.6 1.7 5.7 9.7 1.0 1.1
600 0.28 0.47 0.71 0.75 0.5 0.8 1.2 1.3 5.7 9.7 0.8 0.8
East
"c" pre-con precon c 0.42
"c" post-con postcon c 0.65
east area (SF) 119192 2.74
minutes 2 year in/hr 10 year
in/hr
50 year
in/hr
100 year
in/hr
inflow 2yr
post-con CFS
inflow
10yr post-
con CFS
inflow 50yr
post-con
CFS
inflow
100yr post-
con CFS
outflow 2
yr pre
release CFS
outflow 10
yr pre
release CFS
outflow 50
yr pre
release CFS
outflow 100
yr pre
release CFS
10 2.09 3.58 4.61 5.00 3.7 6.4 8.2 8.9 2.4 4.1 5.3 5.7
15 1.81 2.99 3.90 4.29 3.2 5.3 6.9 7.6 1.0 1.7 4.5 4.9
30 1.18 2.09 2.60 2.91 2.1 3.7 4.6 5.2 1.0 1.7 3.0 3.3
60 0.75 1.30 1.69 1.85 1.3 2.3 3.0 3.3 1.0 1.7 1.9 2.1
120 0.55 0.91 1.30 1.38 1.0 1.6 2.3 2.5 1.0 1.7 1.5 1.6
180 0.47 0.83 1.14 1.22 0.8 1.5 2.0 2.2 1.0 1.7 1.3 1.4
360 0.36 0.63 0.91 0.98 0.6 1.1 1.6 1.8 1.0 1.7 1.0 1.1
600 0.28 0.47 0.71 0.75 0.5 0.8 1.3 1.3 1.0 1.7 0.8 0.9
141 South Elm Street • Arroyo Grande, CA, 93420 • Telephone 805.489.1321 • Fax 805.489.6723 • garingtaylor.com
Ronald G. Reilly, PE | Perry D McBeth, PE | James A. Cooper, PE, LS
William Rebik, PE, LS | Jeffrey J. Emrick, PE
DMA 2 Earthwood Phase I West
"c" pre-con precon c 0.42
"c" post-con postcon c 0.65
DMA 2 area (SF) 48714 1.12 area (AC)
minutes 2 year in/hr 10 year
in/hr
50 year
in/hr
100 year
in/hr
inflow 2yr post-
con CFS
inflow 10yr
post-con
CFS
inflow 50yr
post-con
CFS
inflow 100yr
post-con CFS
outflow 2
yr pre
release CFS
outflow 10
yr pre
release CFS
outflow 50
yr pre
release CFS
outflow 100
yr pre
release CFS
10 2.09 3.58 4.61 5.00 1.5 2.6 3.3 3.6 1.0 1.7 2.2 2.3
15 1.81 2.99 3.90 4.29 1.3 2.2 2.8 3.1 5.7 9.7 1.8 2.0
30 1.18 2.09 2.60 2.91 0.9 1.5 1.9 2.1 5.7 9.7 1.2 1.4
60 0.75 1.30 1.69 1.85 0.5 0.9 1.2 1.3 5.7 9.7 0.8 0.9
120 0.55 0.91 1.30 1.38 0.4 0.7 0.9 1.0 5.7 9.7 0.6 0.6
180 0.47 0.83 1.14 1.22 0.3 0.6 0.8 0.9 5.7 9.7 0.5 0.6
360 0.36 0.63 0.91 0.98 0.3 0.5 0.7 0.7 5.7 9.7 0.4 0.5
600 0.28 0.47 0.71 0.75 0.2 0.3 0.5 0.5 5.7 9.7 0.3 0.4
DMA 3 Earthwood Phase I East
"c" pre-con precon c 0.42
"c" post-con postcon c 0.65
DMA 3 area (SF) 49885 1.15 area (AC)
minutes 2 year in/hr 10 year
in/hr
50 year
in/hr
100 year
in/hr
inflow 2yr post-
con CFS
inflow 10yr
post-con
CFS
inflow 50yr
post-con
CFS
inflow 100yr
post-con CFS
outflow 2
yr pre
release CFS
outflow 10
yr pre
release CFS
outflow 50
yr pre
release CFS
outflow 100
yr pre
release CFS
10 2.09 3.58 4.61 5.00 1.6 2.7 3.4 3.7 1.0 1.7 2.2 2.4
15 1.81 2.99 3.90 4.29 1.3 2.2 2.9 3.2 1.0 1.7 1.9 2.1
30 1.18 2.09 2.60 2.91 0.9 1.6 1.9 2.2 1.0 1.7 1.2 1.4
60 0.75 1.30 1.69 1.85 0.6 1.0 1.3 1.4 1.0 1.7 0.8 0.9
120 0.55 0.91 1.30 1.38 0.4 0.7 1.0 1.0 1.0 1.7 0.6 0.7
180 0.47 0.83 1.14 1.22 0.4 0.6 0.8 0.9 1.0 1.7 0.5 0.6
360 0.36 0.63 0.91 0.98 0.3 0.5 0.7 0.7 1.0 1.7 0.4 0.5
600 0.28 0.47 0.71 0.75 0.2 0.4 0.5 0.6 1.0 1.7 0.3 0.4
141 South Elm Street • Arroyo Grande, CA, 93420 • Telephone 805.489.1321 • Fax 805.489.6723 • garingtaylor.com
Ronald G. Reilly, PE | Perry D McBeth, PE | James A. Cooper, PE, LS
William Rebik, PE, LS | Jeffrey J. Emrick, PE
DMA 4 Earthwood Phase II West
"c" pre-con precon c 0.42
"c" post-con postcon c 0.65
DMA 4 area (SF) 68602 1.57 area (AC)
minutes 2 year in/hr 10 year
in/hr
50 year
in/hr
100 year
in/hr
inflow 2yr
post-con CFS
inflow 10yr
post-con
CFS
inflow 50yr
post-con
CFS
inflow 100yr
post-con CFS
outflow 2
yr pre
release CFS
outflow 10
yr pre
release CFS
outflow 50
yr pre
release CFS
outflow 100
yr pre
release CFS
10 2.09 3.58 4.61 5.00 2.1 3.7 4.7 5.1 1.4 2.4 3.0 3.3
15 1.81 2.99 3.90 4.29 1.9 3.1 4.0 4.4 1.8 3.2 2.6 2.8
30 1.18 2.09 2.60 2.91 1.2 2.1 2.7 3.0 1.8 3.2 1.7 1.9
60 0.75 1.30 1.69 1.85 0.8 1.3 1.7 1.9 1.8 3.2 1.1 1.2
120 0.55 0.91 1.30 1.38 0.6 0.9 1.3 1.4 1.8 3.2 0.9 0.9
180 0.47 0.83 1.14 1.22 0.5 0.8 1.2 1.2 1.8 3.2 0.8 0.8
360 0.36 0.63 0.91 0.98 0.4 0.6 0.9 1.0 1.8 3.2 0.6 0.7
600 0.28 0.47 0.71 0.75 0.3 0.5 0.7 0.8 1.8 3.2 0.5 0.5
DMA 5 Earthwood Phase II East
"c" pre-con precon c 0.42
"c" post-con postcon c 0.65
DMA 5 area (SF) 69307 1.59 area (AC)
minutes 2 year in/hr 10 year
in/hr
50 year
in/hr
100 year
in/hr
inflow 2yr
post-con CFS
inflow 10yr
post-con
CFS
inflow 50yr
post-con
CFS
inflow 100yr
post-con CFS
outflow 2
yr pre
release CFS
outflow 10
yr pre
release CFS
outflow 50
yr pre
release CFS
outflow 100
yr pre
release CFS
10 2.09 3.58 4.61 5.00 2.2 3.7 4.8 5.2 1.4 2.4 3.1 3.3
15 1.81 2.99 3.90 4.29 1.9 3.1 4.0 4.4 1.8 3.1 2.6 2.9
30 1.18 2.09 2.60 2.91 1.2 2.2 2.7 3.0 1.8 3.1 1.7 1.9
60 0.75 1.30 1.69 1.85 0.8 1.3 1.8 1.9 1.8 3.1 1.1 1.2
120 0.55 0.91 1.30 1.38 0.6 0.9 1.3 1.4 1.8 3.1 0.9 0.9
180 0.47 0.83 1.14 1.22 0.5 0.9 1.2 1.3 1.8 3.1 0.8 0.8
360 0.36 0.63 0.91 0.98 0.4 0.7 0.9 1.0 1.8 3.1 0.6 0.7
600 0.28 0.47 0.71 0.75 0.3 0.5 0.7 0.8 1.8 3.1 0.5 0.5
141 South Elm Street • Arroyo Grande, CA, 93420 • Telephone 805.489.1321 • Fax 805.489.6723 • garingtaylor.com
Ronald G. Reilly, PE | Perry D McBeth, PE | James A. Cooper, PE, LS
William Rebik, PE, LS | Jeffrey J. Emrick, PE
Earthwood Phase I & II DMA 2-5
"c" pre-con precon c 0.42
"c" post-con postcon c 0.65
DMA 2-5 area (SF) 236508 5.429477 area (AC)
minutes 100 year in/hr inflow 2yr post-
con CFS
inflow 10yr
post-con CFS
inflow 50yr post-
con CFS
inflow 100yr
post-con CFS
outflow 2 yr pre
release CFS
outflow 10 yr
pre release CFS
outflow 50 yr
pre release CFS
outflow 100 yr
pre release CFS
10 5.00 7.4 12.6 16.3 17.6 4.8 8.2 10.5 11.4
15 4.29 6.4 10.6 13.8 15.1 1.8 3.2 8.9 9.8
30 2.91 4.2 7.4 9.2 10.3 1.8 3.2 5.9 6.6
60 1.85 2.6 4.6 6.0 6.5 1.8 3.2 3.9 4.2
120 1.38 1.9 3.2 4.6 4.9 1.8 3.2 3.0 3.1
180 1.22 1.7 2.9 4.0 4.3 1.8 3.2 2.6 2.8
360 0.98 1.3 2.2 3.2 3.5 1.8 3.2 2.1 2.2
600 0.75 1.0 1.7 2.5 2.6 1.8 3.2 1.6 1.7
DMA 6 Earthwood Phase I & II
"c" pre-con precon c 0.42
"c" post-con postcon c 0.65
DMA 6 area (SF) 44410 1.02 area (AC)
basin area SF 16404
minutes 2 year in/hr 100 year in/hr inflow 2yr post-
con CFS
inflow 10yr post-
con CFS
inflow 50yr post-
con CFS
inflow 100yr post-
con CFS
outflow 2 yr
pre release CFS
outflow 10 yr
pre release CFS
outflow 50 yr
pre release CFS
outflow 100 yr
pre release CFS
10 2.09 5.00 1.4 2.4 3.1 3.3 0.9 1.5 2.0 2.1
15 1.81 4.29 1.2 2.0 2.6 2.8 1.8 3.2 1.7 1.8
30 1.18 2.91 0.8 1.4 1.7 1.9 1.8 3.2 1.1 1.2
60 0.75 1.85 0.5 0.9 1.1 1.2 1.8 3.2 0.7 0.8
120 0.55 1.38 0.4 0.6 0.9 0.9 1.8 3.2 0.6 0.6
180 0.47 1.22 0.3 0.5 0.8 0.8 1.8 3.2 0.5 0.5
360 0.36 0.98 0.2 0.4 0.6 0.7 1.8 3.2 0.4 0.4
600 0.28 0.75 0.2 0.3 0.5 0.5 1.8 3.2 0.3 0.3
DMA 6A Earthwood Phase I & II
"c" pre-con precon c 0.42
"c" post-con postcon c 0.9
DMA 6A area (SF) 9168 0.21 area (AC)
minutes 2 year in/hr 100 year in/hr inflow 2yr post-
con CFS
inflow 10yr
post-con CFS
inflow 50yr
post-con CFS
inflow 100yr
post-con CFS
outflow 2 yr
pre release CFS
outflow 10 yr
pre release CFS
outflow 50 yr
pre release CFS
outflow 100 yr
pre release CFS
10 2.09 5.00 0.4 0.7 0.9 0.9 0.2 0.3 0.4 0.4
GARING, TAYLOR AND ASSOCIATES
TR 3211 1598 EL CAMINO REAL
PAGE 18
Appendix “C”
BASIN STORMDRAIN PLAN & PROFILE
6
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STORM DRAIN & BASIN PROFILE
EARTHWOOD LANE TO BASIN
STORM DRAIN AND BASIN PLAN
STORM DRAIN & BASIN PROFILE
BASIN TO EARTHWOOD LANE
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GARING, TAYLOR AND ASSOCIATES
TR 2943 EARTHWOOD LANE PHASE II
PAGE 20
Appendix “D”
INCREMENTAL BASIN VOLUME
Site:Ernie Ball Basin @ Earthwood
Description:Onsite Retention Volume
GTA Project No. 20-822
Computed: ajc Date: 2/16/2021
Basin New
Incremental Accumulated
Area Volume Volume*
Elevation (ft2) (ft
3) (ft
3)
106.50 12321 00
107.00 12869 6,297 6,297
108.00 13877 3,428 19,628
109.00 14575 14,225 33,853
109.25 14809 3,673 37,526
109.50 15138 3,743 41,269
110.00 15966 7,775 49,044
110.48 16076 7,690 56,734
111.00 17,064 8,615 65,349
112.00 18,211 17,634 82,984
113.00 19,381 8,585 101,740
114.00 20,161 13,950 121,551
114.20 20,376 4,054 125,605
Top 114.23 20,408 612 126,217
*Volume is calculated using conic method
Total Volume = 126,217 cu.ft.
GARING, TAYLOR AND ASSOCIATES
TR 2943 EARTHWOOD LANE PHASE II
PAGE 22
Appendix “E”
HYDRAFLOW REPORT EARTHWOOD LANE INLET 2-YEAR
Inlet Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Wednesday, Feb 17 2021
INLETS LOTS 14 & 17 (2-YEAR)
Curb Inlet
Location = On grade
Curb Length (ft) = 14.50
Throat Height (in) = 4.50
Grate Area (sqft) = -0-
Grate Width (ft) = -0-
Grate Length (ft) = -0-
Gutter
Slope, Sw (ft/ft) = 0.050
Slope, Sx (ft/ft) = 0.020
Local Depr (in) = 4.00
Gutter Width (ft) = 2.00
Gutter Slope (%) = 1.00
Gutter n-value = 0.012
Calculations
Compute by: Known Q
Q (cfs) = 2.10
Highlighted
Q Total (cfs) = 2.10
Q Capt (cfs) = 2.10
Q Bypass (cfs) = -0-
Depth at Inlet (in) = 6.63
Efficiency (%) = 100
Gutter Spread (ft) = 7.95
Gutter Vel (ft/s) = 3.04
Bypass Spread (ft) = -0-
Bypass Depth (in) = -0-
GARING, TAYLOR AND ASSOCIATES
TR 2943 EARTHWOOD LANE PHASE II
PAGE 24
Appendix “F”
HYDRAFLOW REPORT EARTHWOOD LANE INLET 100-YEAR
Inlet Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Wednesday, Feb 17 2021
INLETS LOTS 14 & 17 (100-YEAR)
Curb Inlet
Location = On grade
Curb Length (ft) = 14.50
Throat Height (in) = 4.50
Grate Area (sqft) = -0-
Grate Width (ft) = -0-
Grate Length (ft) = -0-
Gutter
Slope, Sw (ft/ft) = 0.050
Slope, Sx (ft/ft) = 0.020
Local Depr (in) = 4.00
Gutter Width (ft) = 2.00
Gutter Slope (%) = 1.00
Gutter n-value = 0.012
Calculations
Compute by: Known Q
Q (cfs) = 8.85
Highlighted
Q Total (cfs) = 8.85
Q Capt (cfs) = 7.53
Q Bypass (cfs) = 1.32
Depth at Inlet (in) = 8.16
Efficiency (%) = 85
Gutter Spread (ft) = 14.32
Gutter Vel (ft/s) = 4.20
Bypass Spread (ft) = 6.45
Bypass Depth (in) = 2.27
GARING, TAYLOR AND ASSOCIATES
TR 2943 EARTHWOOD LANE PHASE II
PAGE 26
Appendix “G”
HYDRAFLOW REPORT 18” PIPE CROSSING EARTHWOOD
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Friday, Feb 19 2021
18 INCH PIPE CROSSING EARTHWOOD
Invert Elev Dn (ft) = 108.10
Pipe Length (ft) = 45.00
Slope (%) = 2.22
Invert Elev Up (ft) = 109.10
Rise (in) = 18.0
Shape = Circular
Span (in) = 18.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Groove end projecting (C)
Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2
Embankment
Top Elevation (ft) = 114.80
Top Width (ft) = 5.00
Crest Width (ft) = 6.00
Calculations
Qmin (cfs) = 0.00
Qmax (cfs) = 9.00
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 8.85
Qpipe (cfs) = 8.85
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 5.36
Veloc Up (ft/s) = 6.09
HGL Dn (ft) = 109.43
HGL Up (ft) = 110.25
Hw Elev (ft) = 110.92
Hw/D (ft) = 1.21
Flow Regime = Inlet Control
GARING, TAYLOR AND ASSOCIATES
TR 2943 EARTHWOOD LANE PHASE II
PAGE 28
Appendix “H”
HYDRAFLOW REPORT 24” PIPE EARTHWOOD LANE TO BASIN
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Friday, Feb 19 2021
24 INCH PIPE FROM EARTHWOOD LANE TO BASIN
Invert Elev Dn (ft) = 107.00
Pipe Length (ft) = 189.00
Slope (%) = 0.53
Invert Elev Up (ft) = 108.00
Rise (in) = 24.0
Shape = Circular
Span (in) = 24.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Square edge w/headwall (C)
Coeff. K,M,c,Y,k = 0.0098, 2, 0.0398, 0.67, 0.5
Embankment
Top Elevation (ft) = 114.70
Top Width (ft) = 144.00
Crest Width (ft) = 6.00
Calculations
Qmin (cfs) = 0.00
Qmax (cfs) = 18.00
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 17.75
Qpipe (cfs) = 17.75
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 6.07
Veloc Up (ft/s) = 6.94
HGL Dn (ft) = 108.76
HGL Up (ft) = 109.52
Hw Elev (ft) = 110.61
Hw/D (ft) = 1.30
Flow Regime = Inlet Control
GARING, TAYLOR AND ASSOCIATES
TR 2943 EARTHWOOD LANE PHASE II
PAGE 30
Appendix “I”
HYDRAFLOW REPORT 18” OUTFALL FROM BASIN TO EARTHWOOD
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Monday, Feb 22 2021
18 INCH OUTFLOW FROM BASIN
Invert Elev Dn (ft) = 108.47
Pipe Length (ft) = 164.00
Slope (%) = 0.63
Invert Elev Up (ft) = 109.50
Rise (in) = 18.0
Shape = Circular
Span (in) = 18.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Groove end projecting (C)
Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2
Embankment
Top Elevation (ft) = 115.00
Top Width (ft) = 16.00
Crest Width (ft) = 6.00
Calculations
Qmin (cfs) = 0.00
Qmax (cfs) = 17.00
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 17.00
Qpipe (cfs) = 16.84
Qovertop (cfs) = 0.16
Veloc Dn (ft/s) = 9.58
Veloc Up (ft/s) = 9.53
HGL Dn (ft) = 109.94
HGL Up (ft) = 113.36
Hw Elev (ft) = 115.05
Hw/D (ft) = 3.70
Flow Regime = Outlet Control
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Monday, Feb 22 2021
18 INCH OUTFLOW FROM BASIN
Invert Elev Dn (ft) = 108.47
Pipe Length (ft) = 164.00
Slope (%) = 0.63
Invert Elev Up (ft) = 109.50
Rise (in) = 18.0
Shape = Circular
Span (in) = 18.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Groove end projecting (C)
Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2
Embankment
Top Elevation (ft) = 115.00
Top Width (ft) = 16.00
Crest Width (ft) = 6.00
Calculations
Qmin (cfs) = 0.00
Qmax (cfs) = 17.00
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 16.00
Qpipe (cfs) = 16.00
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 9.12
Veloc Up (ft/s) = 9.05
HGL Dn (ft) = 109.93
HGL Up (ft) = 113.01
Hw Elev (ft) = 114.54
Hw/D (ft) = 3.36
Flow Regime = Outlet Control
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Monday, Feb 22 2021
18 INCH OUTFLOW FROM BASIN
Invert Elev Dn (ft) = 108.47
Pipe Length (ft) = 164.00
Slope (%) = 0.63
Invert Elev Up (ft) = 109.50
Rise (in) = 18.0
Shape = Circular
Span (in) = 18.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Groove end projecting (C)
Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2
Embankment
Top Elevation (ft) = 115.00
Top Width (ft) = 16.00
Crest Width (ft) = 6.00
Calculations
Qmin (cfs) = 0.00
Qmax (cfs) = 17.00
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 15.40
Qpipe (cfs) = 15.40
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 8.79
Veloc Up (ft/s) = 8.71
HGL Dn (ft) = 109.93
HGL Up (ft) = 112.77
Hw Elev (ft) = 114.19
Hw/D (ft) = 3.13
Flow Regime = Outlet Control
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Monday, Feb 22 2021
18 INCH OUTFLOW FROM BASIN
Invert Elev Dn (ft) = 108.47
Pipe Length (ft) = 164.00
Slope (%) = 0.63
Invert Elev Up (ft) = 109.50
Rise (in) = 18.0
Shape = Circular
Span (in) = 18.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Groove end projecting (C)
Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2
Embankment
Top Elevation (ft) = 115.00
Top Width (ft) = 16.00
Crest Width (ft) = 6.00
Calculations
Qmin (cfs) = 0.00
Qmax (cfs) = 17.00
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 15.00
Qpipe (cfs) = 15.00
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 8.57
Veloc Up (ft/s) = 8.49
HGL Dn (ft) = 109.92
HGL Up (ft) = 112.62
Hw Elev (ft) = 113.97
Hw/D (ft) = 2.98
Flow Regime = Outlet Control
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Monday, Feb 22 2021
18 INCH OUTFLOW FROM BASIN
Invert Elev Dn (ft) = 108.47
Pipe Length (ft) = 164.00
Slope (%) = 0.63
Invert Elev Up (ft) = 109.50
Rise (in) = 18.0
Shape = Circular
Span (in) = 18.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Groove end projecting (C)
Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2
Embankment
Top Elevation (ft) = 115.00
Top Width (ft) = 16.00
Crest Width (ft) = 6.00
Calculations
Qmin (cfs) = 0.00
Qmax (cfs) = 17.00
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 14.00
Qpipe (cfs) = 14.00
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 8.03
Veloc Up (ft/s) = 7.92
HGL Dn (ft) = 109.91
HGL Up (ft) = 112.26
Hw Elev (ft) = 112.52
Hw/D (ft) = 2.01
Flow Regime = Inlet Control
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Monday, Feb 22 2021
18 INCH OUTFLOW FROM BASIN
Invert Elev Dn (ft) = 108.47
Pipe Length (ft) = 164.00
Slope (%) = 0.63
Invert Elev Up (ft) = 109.50
Rise (in) = 18.0
Shape = Circular
Span (in) = 18.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Groove end projecting (C)
Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2
Embankment
Top Elevation (ft) = 115.00
Top Width (ft) = 16.00
Crest Width (ft) = 6.00
Calculations
Qmin (cfs) = 0.00
Qmax (cfs) = 17.00
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 13.00
Qpipe (cfs) = 13.00
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 7.50
Veloc Up (ft/s) = 7.36
HGL Dn (ft) = 109.90
HGL Up (ft) = 111.93
Hw Elev (ft) = 112.25
Hw/D (ft) = 1.83
Flow Regime = Inlet Control
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Monday, Feb 22 2021
18 INCH OUTFLOW FROM BASIN
Invert Elev Dn (ft) = 108.47
Pipe Length (ft) = 164.00
Slope (%) = 0.63
Invert Elev Up (ft) = 109.50
Rise (in) = 18.0
Shape = Circular
Span (in) = 18.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Groove end projecting (C)
Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2
Embankment
Top Elevation (ft) = 115.00
Top Width (ft) = 16.00
Crest Width (ft) = 6.00
Calculations
Qmin (cfs) = 0.00
Qmax (cfs) = 17.00
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 12.00
Qpipe (cfs) = 12.00
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 6.97
Veloc Up (ft/s) = 6.79
HGL Dn (ft) = 109.88
HGL Up (ft) = 111.62
Hw Elev (ft) = 111.99
Hw/D (ft) = 1.66
Flow Regime = Inlet Control
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Monday, Feb 22 2021
18 INCH OUTFLOW FROM BASIN
Invert Elev Dn (ft) = 108.47
Pipe Length (ft) = 164.00
Slope (%) = 0.63
Invert Elev Up (ft) = 109.50
Rise (in) = 18.0
Shape = Circular
Span (in) = 18.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Groove end projecting (C)
Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2
Embankment
Top Elevation (ft) = 115.00
Top Width (ft) = 16.00
Crest Width (ft) = 6.00
Calculations
Qmin (cfs) = 0.00
Qmax (cfs) = 17.00
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 11.00
Qpipe (cfs) = 11.00
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 6.45
Veloc Up (ft/s) = 6.22
HGL Dn (ft) = 109.85
HGL Up (ft) = 111.33
Hw Elev (ft) = 111.76
Hw/D (ft) = 1.51
Flow Regime = Inlet Control
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Monday, Feb 22 2021
18 INCH OUTFLOW FROM BASIN
Invert Elev Dn (ft) = 108.47
Pipe Length (ft) = 164.00
Slope (%) = 0.63
Invert Elev Up (ft) = 109.50
Rise (in) = 18.0
Shape = Circular
Span (in) = 18.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Groove end projecting (C)
Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2
Embankment
Top Elevation (ft) = 115.00
Top Width (ft) = 16.00
Crest Width (ft) = 6.00
Calculations
Qmin (cfs) = 0.00
Qmax (cfs) = 17.00
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 10.00
Qpipe (cfs) = 10.00
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 5.94
Veloc Up (ft/s) = 5.66
HGL Dn (ft) = 109.83
HGL Up (ft) = 111.07
Hw Elev (ft) = 111.55
Hw/D (ft) = 1.36
Flow Regime = Inlet Control
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Monday, Feb 22 2021
18 INCH OUTFLOW FROM BASIN
Invert Elev Dn (ft) = 108.47
Pipe Length (ft) = 164.00
Slope (%) = 0.63
Invert Elev Up (ft) = 109.50
Rise (in) = 18.0
Shape = Circular
Span (in) = 18.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Groove end projecting (C)
Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2
Embankment
Top Elevation (ft) = 115.00
Top Width (ft) = 16.00
Crest Width (ft) = 6.00
Calculations
Qmin (cfs) = 0.00
Qmax (cfs) = 17.00
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 9.00
Qpipe (cfs) = 9.00
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 5.43
Veloc Up (ft/s) = 5.90
HGL Dn (ft) = 109.80
HGL Up (ft) = 110.71
Hw Elev (ft) = 111.36
Hw/D (ft) = 1.24
Flow Regime = Inlet Control
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Monday, Feb 22 2021
18 INCH OUTFLOW FROM BASIN
Invert Elev Dn (ft) = 108.47
Pipe Length (ft) = 164.00
Slope (%) = 0.63
Invert Elev Up (ft) = 109.50
Rise (in) = 18.0
Shape = Circular
Span (in) = 18.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Groove end projecting (C)
Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2
Embankment
Top Elevation (ft) = 115.00
Top Width (ft) = 16.00
Crest Width (ft) = 6.00
Calculations
Qmin (cfs) = 0.00
Qmax (cfs) = 17.00
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 8.00
Qpipe (cfs) = 8.00
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 4.92
Veloc Up (ft/s) = 5.79
HGL Dn (ft) = 109.77
HGL Up (ft) = 110.59
Hw Elev (ft) = 111.20
Hw/D (ft) = 1.14
Flow Regime = Inlet Control
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Monday, Feb 22 2021
18 INCH OUTFLOW FROM BASIN
Invert Elev Dn (ft) = 108.47
Pipe Length (ft) = 164.00
Slope (%) = 0.63
Invert Elev Up (ft) = 109.50
Rise (in) = 18.0
Shape = Circular
Span (in) = 18.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Groove end projecting (C)
Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2
Embankment
Top Elevation (ft) = 115.00
Top Width (ft) = 16.00
Crest Width (ft) = 6.00
Calculations
Qmin (cfs) = 0.00
Qmax (cfs) = 17.00
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 7.00
Qpipe (cfs) = 7.00
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 4.41
Veloc Up (ft/s) = 5.45
HGL Dn (ft) = 109.73
HGL Up (ft) = 110.52
Hw Elev (ft) = 111.05
Hw/D (ft) = 1.03
Flow Regime = Inlet Control
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Monday, Feb 22 2021
18 INCH OUTFLOW FROM BASIN
Invert Elev Dn (ft) = 108.47
Pipe Length (ft) = 164.00
Slope (%) = 0.63
Invert Elev Up (ft) = 109.50
Rise (in) = 18.0
Shape = Circular
Span (in) = 18.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Groove end projecting (C)
Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2
Embankment
Top Elevation (ft) = 115.00
Top Width (ft) = 16.00
Crest Width (ft) = 6.00
Calculations
Qmin (cfs) = 0.00
Qmax (cfs) = 17.00
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 6.00
Qpipe (cfs) = 6.00
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 3.89
Veloc Up (ft/s) = 5.12
HGL Dn (ft) = 109.69
HGL Up (ft) = 110.45
Hw Elev (ft) = 110.90
Hw/D (ft) = 0.93
Flow Regime = Inlet Control
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Monday, Feb 22 2021
18 INCH OUTFLOW FROM BASIN
Invert Elev Dn (ft) = 108.47
Pipe Length (ft) = 164.00
Slope (%) = 0.63
Invert Elev Up (ft) = 109.50
Rise (in) = 18.0
Shape = Circular
Span (in) = 18.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Groove end projecting (C)
Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2
Embankment
Top Elevation (ft) = 115.00
Top Width (ft) = 16.00
Crest Width (ft) = 6.00
Calculations
Qmin (cfs) = 0.00
Qmax (cfs) = 17.00
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 5.00
Qpipe (cfs) = 5.00
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 3.35
Veloc Up (ft/s) = 4.77
HGL Dn (ft) = 109.65
HGL Up (ft) = 110.36
Hw Elev (ft) = 110.75
Hw/D (ft) = 0.83
Flow Regime = Inlet Control
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Monday, Feb 22 2021
18 INCH OUTFLOW FROM BASIN
Invert Elev Dn (ft) = 108.47
Pipe Length (ft) = 164.00
Slope (%) = 0.63
Invert Elev Up (ft) = 109.50
Rise (in) = 18.0
Shape = Circular
Span (in) = 18.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Groove end projecting (C)
Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2
Embankment
Top Elevation (ft) = 115.00
Top Width (ft) = 16.00
Crest Width (ft) = 6.00
Calculations
Qmin (cfs) = 0.00
Qmax (cfs) = 17.00
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 4.00
Qpipe (cfs) = 4.00
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 2.79
Veloc Up (ft/s) = 4.42
HGL Dn (ft) = 109.60
HGL Up (ft) = 110.26
Hw Elev (ft) = 110.59
Hw/D (ft) = 0.72
Flow Regime = Inlet Control
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Monday, Feb 22 2021
18 INCH OUTFLOW FROM BASIN
Invert Elev Dn (ft) = 108.47
Pipe Length (ft) = 164.00
Slope (%) = 0.63
Invert Elev Up (ft) = 109.50
Rise (in) = 18.0
Shape = Circular
Span (in) = 18.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Groove end projecting (C)
Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2
Embankment
Top Elevation (ft) = 115.00
Top Width (ft) = 16.00
Crest Width (ft) = 6.00
Calculations
Qmin (cfs) = 0.00
Qmax (cfs) = 17.00
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 3.00
Qpipe (cfs) = 3.00
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 2.20
Veloc Up (ft/s) = 4.02
HGL Dn (ft) = 109.55
HGL Up (ft) = 110.16
Hw Elev (ft) = 110.42
Hw/D (ft) = 0.61
Flow Regime = Inlet Control
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Monday, Feb 22 2021
18 INCH OUTFLOW FROM BASIN
Invert Elev Dn (ft) = 108.47
Pipe Length (ft) = 164.00
Slope (%) = 0.63
Invert Elev Up (ft) = 109.50
Rise (in) = 18.0
Shape = Circular
Span (in) = 18.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Groove end projecting (C)
Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2
Embankment
Top Elevation (ft) = 115.00
Top Width (ft) = 16.00
Crest Width (ft) = 6.00
Calculations
Qmin (cfs) = 0.00
Qmax (cfs) = 17.00
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 2.00
Qpipe (cfs) = 2.00
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 1.57
Veloc Up (ft/s) = 3.56
HGL Dn (ft) = 109.49
HGL Up (ft) = 110.03
Hw Elev (ft) = 110.23
Hw/D (ft) = 0.49
Flow Regime = Inlet Control
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Monday, Feb 22 2021
18 INCH OUTFLOW FROM BASIN
Invert Elev Dn (ft) = 108.47
Pipe Length (ft) = 164.00
Slope (%) = 0.63
Invert Elev Up (ft) = 109.50
Rise (in) = 18.0
Shape = Circular
Span (in) = 18.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Groove end projecting (C)
Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2
Embankment
Top Elevation (ft) = 115.00
Top Width (ft) = 16.00
Crest Width (ft) = 6.00
Calculations
Qmin (cfs) = 0.00
Qmax (cfs) = 17.00
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 1.00
Qpipe (cfs) = 1.00
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 0.86
Veloc Up (ft/s) = 2.92
HGL Dn (ft) = 109.41
HGL Up (ft) = 109.87
Hw Elev (ft) = 110.00
Hw/D (ft) = 0.33
Flow Regime = Inlet Control
Culvert Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Monday, Feb 22 2021
18 INCH OUTFLOW FROM BASIN
Invert Elev Dn (ft) = 108.47
Pipe Length (ft) = 164.00
Slope (%) = 0.63
Invert Elev Up (ft) = 109.50
Rise (in) = 18.0
Shape = Circular
Span (in) = 18.0
No. Barrels = 1
n-Value = 0.012
Culvert Type = Circular Concrete
Culvert Entrance = Groove end projecting (C)
Coeff. K,M,c,Y,k = 0.0045, 2, 0.0317, 0.69, 0.2
Embankment
Top Elevation (ft) = 115.00
Top Width (ft) = 16.00
Crest Width (ft) = 6.00
Calculations
Qmin (cfs) = 0.00
Qmax (cfs) = 17.00
Tailwater Elev (ft) = (dc+D)/2
Highlighted
Qtotal (cfs) = 0.25
Qpipe (cfs) = 0.25
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 0.24
Veloc Up (ft/s) = 2.02
HGL Dn (ft) = 109.31
HGL Up (ft) = 109.68
Hw Elev (ft) = 109.74
Hw/D (ft) = 0.16
Flow Regime = Inlet Control