HomeMy WebLinkAboutTract 7141 & 6383 RevBACKGROUND:
The Master Drainage Study for Tract 7141, formerly Tract 5982, and Tract 6383,
was originally approved by the Department of Public Works on May 27, 2006.
The two adjoining tracts are comprised of a total drainage area of 77 acres and
were divided into 33 drainage areas. All stormwater runoff is conveyed, either by
surface flows or pipe flows, into Morningstar. Morningstar in turn then conveys
runoff, again by surface and pipe flow, into the master drainage basin, sitting at
the north east corner of the development.
The original drainage study can be referenced for design approach and
methodology.
Construction of the Morning Drive / SR-178 overcrossing and the elimination of
the Auburn Street extension through Tract 7141/6383 caused revisions to the lot
layout of Tract 7141 Phase 3. Revisions to the lot layout of Tract 7141 Phase 3
triggered a revision to proposed grading of Tract 7141 Phase 2 and Phase 3 to
balance the earthwork between both phases. As a result of revised grading, the
drainage areas indicated within the approved drainage study had to be revised
as well.
PROPOSED CHANGES:
Tentative Tract 7141 was recently revised due to the City’s acquisition of the
westerly 8.7 acres of the project area. Additionally, the City’s realignment of
Morning Drive nullified the approved tentative map’s plan to extend Auburn
Street into the project area. This revision was processed by City Planning under
the “substantial conformance determination” and was approved January 23,
2019. With this substantial conformance determination, Phases 1 and 2 of the
original tentative map remain fully intact, however Phases 3 and 4 have been
dramatically revised and have been consolidated into the third and final phase of
the revised tentative map.
A second substantial conformance determination was made to allow the revision
of Gray Jay Court from a “dog-leg” style cul-de-sac to a standard straight
orientation. This revision allows Lot 10 of Phase 3 to accommodate a constructed
2:1 slope without restricting the “building envelope” of the lot. The slope is
needed to match the Morning Drive roadway slope, constructed with the City’s
aforementioned re-alignment project.
Additional alterations to site drainage resulting from the revised lot layout of
Phase 3 and subsequent site grading revisions are as follows:
Storm drain inlets eliminated within Phases 2 and 3.
Street flows in Phases 2 and 3 drain to existing Morningstar Avenue inlets
and only one inlet being constructed within Phase 3 due to street flows on
the west side of Tachi Avenue exceeding the capacity of the existing inlet
in Morningstar Avenue; southerly portion of Phases 2 and 3 drain to Tract
6383 Phase 3.
Drainage area boundary revised for south portion of site draining to inlet in
6383-2, drainage area reduced. This drainage area will not be considered
in this revision as it was previously approved with a prior revision and the
contributing drainage area has been reduced.
DRAINAGE STUDY REVISION:
This revision will address the revised lot layout of Phase 3, the revised drainage
areas draining to existing inlets in Tract 7141 Phase 1 and Tract 6383 Phase 2.
Surface flows will be analyzed to assure curbs are adequate, and the hydraulic
grade line will be reviewed to assure City Standard “freeboard” is met at the
existing catch basins within Tract 7141 Phase 1 and Tract 6383 Phase 2.
This revision will also address the offsite drainage of the City’s Morning Drive
slope and Caltrans SR-178 WB Morning Drive offramp slope, and size two
retention ponds to accommodate the slope runoff. Pond’s are sized based on the
City’s retention basin sizing calculation – V = 0.15 (C x A) – to determine the
required storage capacity in Acre-Feet.
Onsite and offsite drainage areas are depicted in the attached exhibit (see
Exhibit 1). Subarea designations have been revised to lettered areas and
incorporate the numbered areas of the original report as follows:
Area “A”: 1, 21
Area “B”: Portions of areas 12, 15, & 18
Area “C”: 10, 11, 13 and portions of 10, 11, 12, 13, 15, 16, & 18
Area “D”: 8, 9, & 19
Area “E”: 4, 5, 6, & 7
Area “F”: 1, 2, 3, 17, & 34
Area “G”: Portion of 31, 32, & 33
Area “H”: Portion of 31, 22
Area “I”: Portion of 25 & 26, 28
*Area “J”: Portion of 16 & 26, 27
*Area “K”: 24, portion of 25, 30
Offsite Drainage Area L: Portion of 11, 13, 15 & 16
Offsite Drainage Area M: Portion of 16
*Note: Area “J” and Area “K” not included in this revision. Drainage Study
revisions in 2021 covered Shelby Lynn/Drummond inlet. Total tributary area for
“J” reduced with this revision. No Change to Area “K.”
The maximum flow depth along the curb lines resulting from the 5 year frequency
event (Appendix 1) will be 3.7 inches at the upstream side of Tract 7141 Catch
Basin 4 (7141-CB4), at the northeast corner of Baldivia Court and Tachi Ave.
In order to assure the integrity of results, the curb depth was calculated by
placing the 5-year frequency storm flow within the street’s “actual” gradient just
upstream of the catch basin. Because the 5-year flow rate is determined by the
use of the drainage area’s “average” street gradient, it is the opinion of this
engineer that the traditional measure of the flow depth is distorted when the
street gradient changes dramatically within large drainage areas of north east
Bakersfield.
The 10-year storm frequency was used for the hydraulic analysis (Appendix 4).
The minimum freeboard in this revised system is 2.9 feet at Tract 7141 catch
basin 2 (7141-CB2), at the southwest corner of Morningstar Avenue and
Beaverhead Avenue. The starting HGL elevation of 739 was used for this
analysis, as was utilized in the original study. Results of the hydraulic analysis,
inlet sizes, and profiles showing the hydraulic grade lines are included in
appendix 5.
Offsite Drainage Retention
Offsite drainage from the Morning Drive slope and SR-178 offramp slope will be
directed to shallow depth retention ponds (max water depth = 1.5’) by grassy
swales that intercept runoff at the toe of slope. Ponds are placed at the low
points of the slope subareas as depicted on Exhibit 1.
Retention ponds are sized based on the City’s retention basin sizing calculation:
V = 0.15 (C x A)
Where: V = required design volume, acre-feet
C = runoff coefficient
A = tributary area, acres
The runoff coefficient of C = 0.43 was used for both tributary areas. Both slopes
are primarily 4:1 with slightly steeper portions that reach 3.5:1. Therefore, in the
opinion of this engineer, the City’s runoff coefficient for Landscaped Areas -
Steep Slope, 7%, in heavy soil (C = 0.35), as indicated on standard detail D-2,
should be increased to account for the steeper slope.
Required Volume – Morning Drive Slope:
The required volume for the Morning Drive slope, Offsite Drainage Area L (3.7
ac.) is 0.24 acre-feet. Please refer to Appendix 6 – Offsite Drainage Retention
Pond Calculations for specifics of pond sizing characteristics.
Required Volume – SR-178 WB Morning Drive Offramp Slope
The required volume for the SR-178 WB Morning Drive Offramp slope, Offsite
Drainage Area M (2.3 ac.) is 0.15 acre-feet. Please refer to Appendix 6 – Offsite
Drainage Retention Pond Sizing Calculations for specifics of pond sizing
characteristics.
Exhibit 1
Drainage Area Map
Tract 7141 & Tract 6383
N
S EJ
SHEET
OF
1
1REGISTEREDPROFESSIONALENGINEERBRETTDAWSONNo. 54058Exp. 12/31/23CIVILSTATEOFCALIFORNIASAN JOAQUIN ENGINEERING, INC.Civil Engineering Land Development ServicesDRAINAGE AREASTRACT 7141 AND TRACT 6383200100500
1 inch = 100 feet
TRACT
7141
TRACT
6383
CITY OF BAKERSFIELD, KERN COUNTY CALIFORNIA
DRAINAGE AREA EXHIBIT
TRACT 7141 & TRACT 6383
Appendix 1
5-year Storm
Curb Flows
Tract 7141-63835 yr Gutter Flows Rev. DMorningstar RanchAs Proposed5/31/2022ICQ (cfs)Point of ConcentrationRoof‐GutterΔTotal DeltaTotal CA6383‐CB8 Area A1, N side of Moringstar Ave. to 6383‐CB865.3 2620 2.5% 4.04 15 10.8 25.8 0.8 0.34 102.83.266383‐CB8 Area A2, S side of Moringstar Ave. E of Sweet Grass Dr. to 6383‐CB84.0 450 0.9% 2.10 15 3.6 18.6 1.0 0.34 1.30.42.056383‐CB8 Total/Avg.25.8 0.8 0.34 11.3 3.84 3.2 #N/A6383‐CB4 Area I1, E side of Sweet Grass Drive and portion of Drummond Ave to 6383‐CB42.8 425 0.7% 1.77 15 4.0 19.0 1.0 0.34 1.40.52.256383‐CB4 Area I2, SE side of Sweet Grass Dr. to 6383‐CB414.7 635 2.3% 3.21 15 3.3 18.3 1.0 0.34 1.90.72.136383‐CB4 Total/Avg19.0 1.0 0.34 3.3 1.12 1.1 N/A6383‐CB3 Area H1, NW side of Sweet Grass Dr & S side of Morningstar from Anaconda to Sweet Grass to 6383‐CB39.4 660 1.4% 2.33 15 4.7 19.7 1.0 0.34 1.650.52.146383‐CB3 Area H2, SW side of Sweet Grass Dr & N side of Seth Alexander from Anaconda to Sweet to Sweet Grass to 6383‐CB320.1 832 2.4% 3.28 15 4.2 19.2 1.0 0.34 2.350.82.226383‐CB3 Total/Avg19.7 1.0 0.34 4 1.36 1.3 N/ACurb Depth (in)Area (ac)tc (min)Area Description Delta HL (ft) S (%) V (fps)https://netorgft8643718.sharepoint.com/sites/Projects/Shared Documents/Files/LGI-Homes/Morningstar-Ranch/z. Drainage-Study/Revisions-2022/curb-street-flow-7141-6383Page 1 of 3
Tract 7141-63835 yr Gutter Flows Rev. DMorningstar RanchAs Proposed5/31/2022ICQ (cfs)Point of ConcentrationRoof‐GutterΔTotal DeltaTotal CACurb Depth (in)Area (ac)tc (min)Area Description Delta HL (ft) S (%) V (fps)6383‐CB2 Area G1, NE side of Anaconda Ave to 6383‐CB22.7 530 0.5% 1.73 15 5.1 20.1 1.0 0.34 1.50.52.376383‐CB2 Area G2, SE side of Anaconda Ave to 6383‐CB213.7 594 2.3% 3.13 15 3.2 18.2 1.0 0.34 1.70.62.036383‐CB220.1 1.0 0.34 3.2 1.09 1.0 N/A6383‐CB1 Area F1, E side of Chukchansi Ave, NW side of Anaconda Ave to6383CB121.7 1740 1.2% 2.75 15 10.6 25.6 0.8 0.34 51.42.936383‐CB1 Area F2, SW side of Anaconda Ave to 6383 CB118.7 780 2.4% 3.21 15 4.1 19.1 1.0 0.34 2.10.72.136383‐CB125.6 0.8 0.34 7.1 2.41 2.0 N/A7141‐CB3 Area E1, E side of Beaverhead Ave & S side of Morningstar Ave between Beaverhead & Chukchansi to 7141 CB324.5 1300 1.9% 3.31 15 6.5 21.5 0.9 0.34 51.62.877141‐CB3 Area E2, W side of Chukchansi Ave and N side of Seth Alexander Way to 7141‐CB313.5 1300 1.0% 2.40 15 9.0 24.0 0.9 0.34 2.10.62.267141‐CB324.0 0.9 0.34 7.1 2.41 2.1 N/A7141‐CB2 Area D1, E side of Tachi Ave to 7141‐CB231.7 1300 2.4% 3.46 15 6.3 21.3 0.9 0.34 3.51.12.457141‐CB2 Area D2, W side of Beaverhead Ave to 7141‐CB230.0 1280 2.3% 3.51 15 6.1 21.1 0.9 0.34 3.81.22.517141‐CB221.3 0.9 0.34 7.3 2.48 2.3 N/Ahttps://netorgft8643718.sharepoint.com/sites/Projects/Shared Documents/Files/LGI-Homes/Morningstar-Ranch/z. Drainage-Study/Revisions-2022/curb-street-flow-7141-6383Page 2 of 3
Tract 7141-63835 yr Gutter Flows Rev. DMorningstar RanchAs Proposed5/31/2022ICQ (cfs)Point of ConcentrationRoof‐GutterΔTotal DeltaTotal CACurb Depth (in)Area (ac)tc (min)Area Description Delta HL (ft) S (%) V (fps)7141‐CB1 Area B, Canvasback Ct, Ivory Gull Ave and S side of Morningstar between Morning drive and Tachi Ave to 7141‐CB137.0 1100 3.4% 4.47 15 4.1 19.1 1.0 0.35 5.61.92.727141‐CB119.1 1.0 0.35 5.6 1.96 1.9 N/A7141‐CB4 Area C, W side of Tachi Ave, Gray Jay Ct and S side of Baldivia Ct to 7141‐CB447.6 980 4.9% 5.65 15 2.9 17.9 1.0 0.38 103.93.247141‐CB417.9 1.0 0.38 10 3.80 3.9 N/Ahttps://netorgft8643718.sharepoint.com/sites/Projects/Shared Documents/Files/LGI-Homes/Morningstar-Ranch/z. Drainage-Study/Revisions-2022/curb-street-flow-7141-6383Page 3 of 3
Appendix 2
5-year Storm
Curb Depths
Tract 6383-59825 yr Gutter DepthsMorningstar RanchAs Proposed5/31/2022ICQ (cfs)Point of ConcentrationRoof‐GutterΔTotal DeltaTotal CA6383‐CB8 Area A1, N side of Moringstar Ave. to 6383‐CB865.3 26200.5%2.21 15 19.8 34.8 0.7 0.34 10 2.33.796383‐CB8 Area A2, S side of Moringstar Ave. E of Sweet Grass Dr. to 6383‐CB84.0 4500.6%1.78 15 4.2 19.2 1.0 0.34 1.3 0.42.166383‐CB8 Total/Avg.34.8 0.7 0.34 11.3 3.84 2.6 #N/A6383‐CB4 Area I1, E side of Sweet Grass Drive and portion of Drummond Ave to 6383‐CB42.8 4250.3%1.42 15 5.0 20.0 1.0 0.34 1.4 0.52.566383‐CB4 Area I2, SE side of Sweet Grass Dr. to 6383‐CB414.71 6352.2%3.21 15 3.3 18.3 1.0 0.34 1.9 0.72.136383‐CB4 Total/Avg20.0 1.0 0.34 3.3 1.12 1.1 N/A6383‐CB3 Area H1, NW side of Sweet Grass Dr & S side of Morningstar from Anaconda to Sweet Grass to 6383‐CB39.39 6601.6%2.74 15 4.0 19.0 1.0 0.34 1.65 0.62.016383‐CB3 Area H2, SW side of Sweet Grass Dr & N side of Seth Alexander from Anaconda to Sweet to Sweet Grass to 6383‐CB320.05 8322.2%3.28 15 4.2 19.2 1.0 0.34 2.35 0.82.226383‐CB3 Total/Avg19.2 1.0 0.34 4 1.36 1.3 N/AArea (ac)Curb Depth (in)Area Description Delta HL (ft) S (%) V (fps)tc (min)https://netorgft8643718.sharepoint.com/sites/Projects/Shared Documents/Files/LGI-Homes/Morningstar-Ranch/z. Drainage-Study/Revisions-2022/curb-street-flow-7141-6383Page 1 of 3
Tract 6383-59825 yr Gutter DepthsMorningstar RanchAs Proposed5/31/2022ICQ (cfs)Point of ConcentrationRoof‐GutterΔTotal DeltaTotal CAArea (ac)Curb Depth (in)Area Description Delta HL (ft) S (%) V (fps)tc (min)6383‐CB2 Area G1, NE side of Anaconda Ave to 6383‐CB22.66 5300.2%1.21 15 7.3 22.3 0.9 0.34 1.5 0.52.796383‐CB2 Area G2, SE side of Anaconda Ave to 6383‐CB213.66 5942.8%3.13 15 3.2 18.2 1.0 0.34 1.7 0.62.036383‐CB222.3 0.9 0.34 3.2 1.09 1.0 N/A6383‐CB1 Area F1, E side of Chukchansi Ave, NW side of Anaconda Ave to 6383 CB121.66 17401.3%2.75 15 10.6 25.6 0.8 0.34 5 1.42.936383‐CB1 Area F2, SW side of Anaconda Ave to 6383 CB118.66 7802.8%3.21 15 4.1 19.1 1.0 0.34 2.1 0.72.136383‐CB125.6 0.8 0.34 7.1 2.41 2.0 N/A7141‐CB3 Area E1, E side of Beaverhead Ave & S side of Morningstar Ave between Beaverhead & Chukchansi to 7141 CB324.47 13001.9%3.31 15 6.5 21.5 0.9 0.34 5 1.62.877141‐CB3 Area E2, W side of Chukchansi Ave and N side of Seth Alexander Way to 7141‐CB313.47 13001.5%2.82 15 7.7 22.7 0.9 0.34 2.1 0.62.127141‐CB322.7 0.9 0.34 7.1 2.41 2.2 N/A7141‐CB2 Area D1, E side of Tachi Ave to 7141‐CB231.65 13002.0%3.46 15 6.3 21.3 0.9 0.34 3.5 1.12.457141‐CB2 Area D2, W side of Beaverhead Ave to 7141‐CB230.85 12801.8%3.16 15 6.8 21.8 0.9 0.34 3.8 1.22.637141‐CB221.8 0.9 0.34 7.3 2.48 2.3 N/Ahttps://netorgft8643718.sharepoint.com/sites/Projects/Shared Documents/Files/LGI-Homes/Morningstar-Ranch/z. Drainage-Study/Revisions-2022/curb-street-flow-7141-6383Page 2 of 3
Tract 6383-59825 yr Gutter DepthsMorningstar RanchAs Proposed5/31/2022ICQ (cfs)Point of ConcentrationRoof‐GutterΔTotal DeltaTotal CAArea (ac)Curb Depth (in)Area Description Delta HL (ft) S (%) V (fps)tc (min)7141‐CB1 Area B, Canvasback Ct, Ivory Gull Ave and S side of Morningstar between Morning drive and Tachi Ave to 7141‐CB136.96 11002.3%3.79 15 4.8 19.8 1.0 0.35 5.6 1.92.897141‐CB119.8 1.0 0.35 5.6 1.96 1.9 N/A7141‐CB4 Area C, W side of Tachi Ave, Gray Jay Ct and S side of Baldivia Ct to 7141‐CB447.64 9801.8%3.81 15 4.3 19.3 1.0 0.38 10 3.83.747141‐CB419.3 1.0 0.38 10 3.80 3.8 N/Ahttps://netorgft8643718.sharepoint.com/sites/Projects/Shared Documents/Files/LGI-Homes/Morningstar-Ranch/z. Drainage-Study/Revisions-2022/curb-street-flow-7141-6383Page 3 of 3
Appendix 3
10-year Storm
Inlet Flows
Tract 7141-638310 yr Inlet Flows Time of Concentrationfor10 yr. stormAs Proposed5/31/2022ICPoint of ConcentrationRoof‐GutterΔTotalΔTotal CA6383 CB8 Area A1, N side of Moringstar Ave. to 6383‐CB865.3 2620 2.5% 4.04 15 10.8 25.8 1.0 0.34 10 3.36383 CB8 Area A2, S side of Moringstar Ave. E of Sweet Grass Dr. to 6383‐CB84.0 450 0.9% 2.10 15 3.6 18.6 1.2 0.34 1.3 0.56383 CB8 Total/Avg.25.8 1.0 0.34 11.3 3.84 3.76383 CB4 Area I1, E side of Sweet Grass Drive and portion of Drummond Ave to 6383‐CB42.8 425 0.7% 1.77 15 4.0 19.0 1.2 0.34 1.4 0.66383 CB4 Area I2, SE side of Sweet Grass Dr. to 6383‐CB414.7 635 2.3% 3.21 15 3.3 18.3 1.2 0.34 1.9 0.86383 CB4 Total/Avg19.0 1.2 0.34 3.3 1.12 1.36383 CB3 Area H1, NW side of Sweet Grass Dr & S side of Morningstar from Anaconda to Sweet Grass to 6383‐CB39.4 660 1.4% 2.33 15 4.7 19.7 1.2 0.34 1.65 0.66383 CB3 Area H2, SW side of Sweet Grass Dr & N side of Seth Alexander from Anaconda to Sweet to Sweet Grass to 6383‐CB320.1 832 2.4% 3.28 15 4.2 19.2 1.2 0.34 2.35 0.96383 CB3 Total/Avg19.7 1.2 0.34 4 1.36 1.66383‐CB2 Area G1, NE side of Anaconda Ave to 6383‐CB22.7 530 0.5% 1.73 15 5.1 20.1 1.1 0.34 1.5 0.6Area (ac)tc (min)Area Description Delta HL (ft) S (%) V (fps)Q(cfs)https://netorgft8643718.sharepoint.com/sites/Projects/Shared Documents/Files/LGI-Homes/Morningstar-Ranch/z. Drainage-Study/Revisions-2022/curb-street-flow-7141-638310 yr Inlet FlowsPage 1 of 3
Tract 7141-638310 yr Inlet Flows Time of Concentrationfor10 yr. stormAs Proposed5/31/2022ICPoint of ConcentrationRoof‐GutterΔTotalΔTotal CAArea (ac)tc (min)Area Description Delta HL (ft) S (%) V (fps)Q(cfs)6383‐CB2 Area G2, SE side of Anaconda Ave to 6383‐CB213.7 594 2.3% 3.13 15 3.2 18.2 1.2 0.34 1.7 0.76383‐CB220.1 1.1 0.34 3.2 1.09 1.26383‐CB1 Area F1, E side of Chukchansi Ave, NW side of Anaconda Ave to 6383 CB121.7 1740 1.2% 2.75 15 10.6 25.6 1.0 0.34 5 1.76383‐CB1 Area F2, SW side of Anaconda Ave to 6383 CB118.7 780 2.4% 3.21 15 4.1 19.1 1.2 0.34 2.1 0.86383‐CB125.6 1.0 0.34 7.1 2.41 2.47141‐CB3 Area E1, E side of Beaverhead Ave & S side of Morningstar Ave between Beaverhead & Chukchansi to 7141 CB324.5 1300 1.9% 3.31 15 6.5 21.5 1.1 0.34 5 1.97141‐CB3 Area E2, W side of Chukchansi Ave and N side of Seth Alexander Way to 7141‐CB313.5 1300 1.0% 2.40 15 9.0 24.0 1.0 0.34 2.1 0.77141‐CB324.0 1.0 0.34 7.1 2.41 2.57141‐CB2 Area D1, E side of Tachi Ave to 7141‐CB231.7 1300 2.4% 3.46 15 6.3 21.3 1.1 0.34 3.5 1.37141‐CB2 Area D2, W side of Beaverhead Ave to 7141‐CB230.0 1280 2.3% 3.51 15 6.1 21.1 1.1 0.34 3.8 1.47141‐CB221.3 1.1 0.34 7.3 2.48 2.7https://netorgft8643718.sharepoint.com/sites/Projects/Shared Documents/Files/LGI-Homes/Morningstar-Ranch/z. Drainage-Study/Revisions-2022/curb-street-flow-7141-638310 yr Inlet FlowsPage 2 of 3
Tract 7141-638310 yr Inlet Flows Time of Concentrationfor10 yr. stormAs Proposed5/31/2022ICPoint of ConcentrationRoof‐GutterΔTotalΔTotal CAArea (ac)tc (min)Area Description Delta HL (ft) S (%) V (fps)Q(cfs)7141‐CB1 Area B, Canvasback Ct, Ivory Gull Ave and S side of Morningstar between Morning drive and Tachi Ave to 7141‐CB137.0 1100 3.4% 4.47 15 4.1 19.1 1.2 0.35 5.6 2.37141‐CB119.1 1.2 0.35 5.6 1.96 2.37141‐CB4 Area C, W side of Tachi Ave, Gray Jay Ct and S side of BaldiviaCtto7141‐CB447.6 980 4.9% 5.65 15 2.9 17.9 1.2 0.38 10 4.77141‐CB417.9 1.2 0.38 10 3.80 4.7From Drainage Study for Tract 55405540 CB4 Tc for CB1 21.8Pipe Flow from CB1 to CB4 223 2.34 1.6 23.4 1.0 0.34 18.19 6.18 6.42https://netorgft8643718.sharepoint.com/sites/Projects/Shared Documents/Files/LGI-Homes/Morningstar-Ranch/z. Drainage-Study/Revisions-2022/curb-street-flow-7141-638310 yr Inlet FlowsPage 3 of 3
Appendix 4
Hydraflow Pipe Flow
Hydraulic Calculations
Inlet Size Calculations
Determine: Capacity of Kern County Type A minor structure for 10‐year storm depth.
Given: Kern County Development Standards Plates R‐71 and R‐72. HEC‐12 inlets in sag condition, Fig. 1.
Analysis:
Where: CW =2.3 Weir Coefficient
L = Length of Opening, ft.
W = Width of Gutter Depression (lateral), ft.
d = Depth at curb measured from normal cross slope, ft.
Where: h = height of curb opening inlet, ft.
a = depth of depression, in.
From Plate R‐72
d = 0.63 ft
h = 0.39 ft
a =2in
Check Is: 0.63 ≤ 0.39 + 2/12
0.63 ≤ 0.55666667 No. Flows in orifice condition.
Given: Inclined throat curb opening (condition b, Fig. 21)
Determine: Capacity @ Kern County 10‐year flow condition
Where: C0 =0.67 orifice coefficient
h = 0.39 orifice throat height, ft. Plate R‐72
L = Length of Opening, ft.
g = 32.2
ft/s2, accel. due to gravity
d0 =0.58 = di ‐ (h/2) sin Q, effective head on center of orifice throat
di =0.77 = 0.10'+0.5'+0.17', water depth at top of incline,
assume to back of walk, Sec. 405‐1.02
Q10‐yr Capacity = (0.67) x (0.39) x L x (2 x 32.2 x 0.58)0.5
= 1.597 L
L =Q10‐yr Capacity / 1.60
Check Lmin Q10‐yr Capacity L (ft)Lmin (ft)
7141‐CB1 2.31 1.45 3.5
7141‐CB2 2.74 1.71 3.5
7141‐CB3 2.46 1.54 3.5
6383‐CB1 2.37 1.48 3.5
6383‐CB2 1.24 0.78 3.5
6383‐CB3 1.57 0.98 3.5
6383‐CB4 1.33 0.83 3.5
6383‐CB8 3.74 2.34 3.5
For Orifice Condition
Q = C0 h L (2g d0)0.5
Determine flow condition for 10‐year storm
For weir conditions:
Q = CW (L + 1.8W) d1.5
To Flow in this condition
d ≤ h + a/12
SAN JOAQUIN ENGINEERING, INC.
Civil Engineering / Land Development Services
200 NEW STINE ROAD, SUITE 175, BAKERSFIELD, CA 93309
PHONE/FAX: 661‐336‐0977 // EMAIL: BDAWSON@SJE2INC.NET
CATCH BASIN TYPE "A" SIZING CALCULATION
TRACT No. 7141/6383
Determine: Capacity of Kern County Type A minor structure for 10‐year storm depth.
Given: Kern County Development Standards Plates R‐71 and R‐72. HEC‐12 inlets on grade condition. Fig. 1.
FHWA Publication 10‐009, Chart 2B
Analysis:
Where: Ku =0.6
LT =Length of Opening required to intercept 100% of gutter flow, ft.
SL = Longitudinal Slope, ft/ft
Q =10‐yr Gutter flow, cfs
Se = Equivalent Cross Slope in depressed gutter section
n = 0.016 Manning's coefficient for broom finished PCC gutter
Sx =cross slope of pavement
Sw =a / [12 W] cross slope of gutter measured from cross slope of pavement
W = 2 gutter width, ft.
a = 2 depth of gutter depression, in.
Sw =2 in/[12*2 ft] = 0.0833333
Eo =Ratio of flow in the depressed section to total gutter flow
(per FHWA Publication 10‐009, Chart 2B)
Eo =0.68
Se =0.02 + 0.0833 * 0.68
Se = 0.077 ft/ft
Determine: LT For 7141‐CB4 Ku =0.6
SL =0.03
Q =4.68
Se = 0.077
LT = 22.361772
Where: E =Inlet capture efficiency
L =4.50Proposed Length of Inlet Opening, ft.
LT =Length of Opening required to intercept 100% of gutter flow, ft.
E = 1 ‐ [ 1 ‐ (6.0/22.4)]1.8
= 0.33
Bypass Flow to 7141‐CB1
Se = Sx + Sw Eo
E = 1 ‐ [ 1 ‐ (L / LT)]1.8
Capture efficiency of 7141‐CB4
Qbypass = Q ‐ Qi
Determine curb opening length required to intercept 100% of the gutter flow
LT = Ku Q0.42 SL
0.3 [1/(n Se)]0.6
SAN JOAQUIN ENGINEERING, INC.
Civil Engineering / Land Development Services
200 NEW STINE ROAD, SUITE 175, BAKERSFIELD, CA 93309
PHONE/FAX: 661‐336‐0977 // EMAIL: BDAWSON@SJE2INC.NET
CATCH BASIN TYPE "A" SIZING CALCULATION
TRACT No. 7141/6383
Where: Q = Total gutter flow, cfs
Qi = QE Flow captured by inlet, cfs
Qbypass = 3.12 cfs
Check Downstream drain inlet 7141‐CB1 can handle additional flow, Qbypass.
QCapacity = 1.60 L
L = 3.5 ft, min
QCapacity = 5.6 cfs
Flow from 7141‐CB1 and Qbypass is less than QCapacity
Qcapacity > Q7141‐CB1 + Qbypass
5.6 cfs > 2.3 cfs + 3.12 cfs
5.6 cfs > 5.42 cfs Checks
Appendix 5
Hydraflow Pipe Flow
HGL Line Profiles
Inlet Section Diagrams
Appendix 6
Offsite Drainage
Retention Pond
Sizing Calculations
SLOPE 1 - Morning Drive Slope
Area A = 3.7 Acres
Runoff Coefficient C = 0.43
V Design Volume (acre-ft)
C Runoff Coefficient by Development Type
A drainage area (acres)
(C x A) = 1.59
V = 0.24 ac‐ft Required Volume
Volume Provided
Bottom Area: 5,500 SF
Vcapacity:0.24 acre‐ft
Area (at Max Water Depth): 8,600 SF
Side Slope: 4:1
Max Water Depth: 1.5 ft
Physical Depth: 2.5 ft
o 2
SAN JOAQUIN ENGINEERING, INC.
Civil Engineering / Land Development Services
200 New Stine Road, Suite 175, Bakersfield, CA 93309
PHONE/FAX: 661-336-0977 // EMAIL: BDAWSON@SJE2INC.NET
RETENTION POND SIZING CALCULATION
MORNINGSTAR RANCH - TRACT 7141
Required Volume
Retention Basin Capacity - City of Bakersfield Method
V = 0.15 x (C x A)
MORNING DRIVE SLOPE - RETENTION POND SIZING
Design Criteria
SLOPE 2 - Caltrans SR-178 WB Morning Drive Offramp Slope
Area A = 2.3 Acres
Runoff Coefficient C = 0.43
V Design Volume (acre-ft)
C Runoff Coefficient by Development Type
A drainage area (acres)
(C x A) = 0.99
V = 0.15 ac‐ft Required Volume
Volume Provided
Bottom Area: 3,500 SF
Vcapacity:0.16 acre‐ft
Top Area (Max Water Depth): 6,000 SF
Side Slope: 4:1
Max Water Depth: 1.5 ft
Physical Depth: 2.5 ft
MORNING DRIVE SLOPE - RETENTION POND SIZING
Design Criteria
Required Volume
Retention Basin Capacity - City of Bakersfield Method
V = 0.15 x (C x A)
SAN JOAQUIN ENGINEERING, INC.
Civil Engineering / Land Development Services
200 New Stine Road, Suite 175, Bakersfield, CA 93309
PHONE/FAX: 661-336-0977 // EMAIL: BDAWSON@SJE2INC.NET
RETENTION POND SIZING CALCULATION
MORNINGSTAR RANCH - TRACT 7141