HomeMy WebLinkAboutTR 32996 OFFSITE HYDROLOGY REPORT Tract 32996
City of Lake Elsinore
OffsKe Hydru� ugy
Prepared By:
Canty Engineering Group, Inc.
2010 Iowa Avenue, Suite 110
Riverside, Ca 92507
951 -683-5234
i
951 -683-5301 fax
March 7, 2005
TRACT 32996-HYDROLOGY
Project Location
Tract 32996 is located in the City of Lake Elsinore in the County of Riverside. The proposed
development consists of 48 single family detached lots on approximately 12 acres. The site is
located northeasterly o Grand Avenue and northwesterly of Riverside Avenue. The project is
adjacent to new high school on the northeast, an apartment complex on the southwest, an
existing improved concrete storm channel on south east, undeveloped land and large lots to the
northwest and a single family development to the west.
Existing Drainage Condition - Offsite
The West Elsinore MDP (RCFC) indicates that under ultimate development 1,450 CFS will flow
southeasterly from Machado along the northeasterly tract boundary to the existing concrete
trapezoidal channel at the easterly corner of the site.
In order for the ultimate flow to reach the project, Lines A, A-1, A-2 and A-3 of the MDP must be
complete. Currently the MDP has not been constructed. The plans for the upstream facility are
being completed by RCFC but there is a problem with getting permits from the regulatory
agencies (Corps of Engineers, U.S. Forest Service). The District is examining alternate methods
to handle the flow as required by the agencies. Until such time as the MDP for this area has
been constructed it will be necessary to provide for the flow reaching the site under existing
conditions.
A field review of the drainage basin indicates the following:
• There is an existing ditch along the northeasterly boundary of Tract 32996 that turns westerly
and northwesterly to a 5'x8' box culvert under Machado with approximately 341- of cover.
• The ditch extends upstream to the outlet of the first stage of Line "A-1" and southwesterly to
Grand Ave. The design flow from Line A-1 is 328 cfs.
• The ditch loses its definition just northeasterly of Grand Ave. and flow upstream from that
location will be sheet flow.
• Grand Avenue appears to have a low approximately 650 feet northwest of Machado with a
high point between the low and Machado.
• There is an undefined water course south west of Grand Avenue that crosses Grand Ave. at
the low. There was little evidence of any storm water after the January storms crossing the
street.
• The upstream canyon that is to be intercepted by Line "A" does not appear, from the
available topography and a field review, to be able to convey the 100-year flow flows behind
homes on Mandeville Way from southwesterly of Nottingham Street to Laguna Ave. There is
evidence of storm flows escaping onto both Nottingham and Laguna. The defined course
has been effectively blocked by the construction of Laguna Ave. across the water course and
the construction of homes into the water course.
• Excess flows will migrate southeasterly and then northeasterly in and through the existing
development along Laguna Ave. and then northeasterly to Grand Ave.
• The flows that escape the ditch will migrate to Grand Ave. The exact location can not be
accurately determined with the available topography. It is probable that some of the flow will
continue southeasterly in Grand Ave. past Machado but a portion of the flow could flow
northeast in Machado.
Until the balance of the Line A has been constructed the actual flow reaching the site will be
determined. A modification of the hydrology map used by RCFC in the preparation of the MDP
has been completed based on the above field review and an interim 100-year storm flow has
been determined as 731 cfs. See synthetic unit hydrograph enclosed herein.
The capacity of the existing crossing of Machado in the 5' x 8' RCB will be approximately 500
cfs. The downstream earthen ditch varies in capacity from approximately 220 cfs to almost 800
cfs. (Normal depth calculations are shown on enclosed topography). The balance of the flow not
contained in the culvert will cross Machado and will either enter the existing ditch or when the
capacity of the ditch is exceeded sheet flow southeasterly toward the northwest boundary of
Tract 32996.
Proposed Drainage Condition
Until such time as the Line A facilities from the MDP have been constructed it will be necessary
to protect the tract from flooding. Constructing Ulla Lane with a high point just northwest of
Lot 46 will permit the construction of a graded broad swale northeasterly along the northwest
boundary of Tract 329960 to the existing ditch adjacent to the high school. That ditch will need
to then be modified to convey the flow southeasterly to the existing concrete RCFC channel.
Ulla Lane south of Lot 46, Lot "D" Open Space, and the open area in Lots 17 and 18 will
provide relief in the event of an unusually high storm water flow.
t
U n i t H y d r o g r a p h A n a l y s i s
Copyright (c) CIVILCADD/CIVILDESIGN, 1989 - 1999, Version 6.0
Study date 03/03/05 File: eulal100.out
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
------------------------------------------------------------------------
Riverside County Synthetic Unit Hydrology Method
RCFC & WCD Manual date - ADril 1978
Canty Engineering Group, Riverside, CA - SIN 693
---------------------------------------------------------------------
English (in-lb) Input Units Used
English Rainfall Data (Inches) Input Values Used
English Units used in output format
---------------------------------------------------------------------
Drainage Area = 355.00 (Ac. ) = 0.555 Sq. Mi.
Length along longest watercourse = 8000.00 (Ft. )
Length along longest watercourse measured to centroid = 4000.00 (Ft. )
Length along longest watercourse = 1.515 Mi.
Length along longest watercourse measured to centroid = 0.758 Mi.
Difference in elevation = 920.00 (Ft. )
Slope along watercourse = 607.2000 Ft. /Mi.
Average Manning's 'N' = 0.030
Lag time = 0.225 Hr.
Lag time = 13.47 Min.
25% of lag time = 3.37 Min.
40% of lag time = 5.39 Min.
Unit time = 5.00 Min.
Duration of tstorm = 1 Hour(s)
User Entered Base Flow = 0.00 (CFS)
2 YEAR Area rainfall data:
Area(Ac. ) [1] Rainfall (In) [2] Weighting[1*2]
355. 00 0. 60 213.00
100 YEAR Area rainfall data:
Area(Ac. ) [1] Rainfall (In) [2] Weighting[1*2]
355. 00 1.50 532.50
STORM EVENT (YEAR) = 100.00
Area Averaged 2-Year Rainfall = 0. 600 (In)
Area Averaged 100-Year Rainfall = 1.500 (In)
Point rain (area averaged) = 1.500 (In)
Areal adjustment factor = 99.68 %
Adjusted average point rain = 1.495 (In)
Sub-Area Data:
Area(Ac. ) Runoff Index Impervious %
355.000 77.00 0.000
Total Area Entered = 355.00 (Ac. )
RI RI Infil. Rate Impervious Adj . Infil. Rate Area% F
AMC2 AMC-2 (In/Hr) (Dec.%) (In/Hr) (Dec. ) (In/Hr)
77.0 77.0 0.279 0.000 0.279 1.000 0.279
Sum (F) = 0.279
Area averaged mean soil loss (F) (In/Hr) = 0.279
Minimum soil loss rate ( (In/Hr) ) = 0.140
(for 24 hour storm duration)
Soil low loss rate (decimal) = 0.900
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Slope of intensity-duration curve for a 1 hour storm =0.4800
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U n i t H y d r o g r a p h
Combination of 'S' Curves:
VALLEY 'S' Curve Percentage = 50.00
FOOTHILL 'S' Curve Percentage = 50.00
MOUNTAIN 'S' Curve Percentage = 0.00
DESERT 'S' Curve Percentage = 0.00
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Unit Hydrograph Data
Unit time period Time % of lag Distribution Unit Hydrograph
(hrs) Graph % (CFS)
---------------------------------------------------------------------
1 0.083 37.116 3.365 12.040
2 0.167 74.232 12. 902 46.160
3 0.250 111.349 25.727 92.045
4 0.333 148.465 22.224 79.511
5 0.417 185.581 10.087 36.089
6 0.500 222. 697 6.346 22.703
7 0.583 259.814 4 . 612 16.501
8 0. 667 296. 930 3. 493 12.498
9 0.750 334 .046 2. 643 9.456
10 0.833 371.162 2.019 7.222
11 0. 917 408.279 1.498 5.358
12 1.000 445.395 0. 975 3.487
13 1.083 482.511 0.788 2.820
14 1.167 519.627 0.712 2.546
15 1.250 556.744 0.544 1. 945
16 1.333 593.860 0.495 1.771
17 1.417 630. 976 0. 431 1.541
18 1.500 668.092 0.323 1.155
19 1.583 705.209 0.251 0.897
20 1. 667 742.325 0.186 0.664
21 1.750 779.441 0.186 0. 664
22 1.833 816.557 0. 196 0.700
Sum = 100.000 Sum= 357.773
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Unit Time Pattern Storm Rain Loss rate (In./Hr) Effective
(Hr. ) Percent (In/Hr) Max Low (In/Hr)
1 0.08 4 .40 0.789 0.279 --- 0.51
2 0.17 4 .50 0.807 0.279 --- 0.53
3 0.25 5.40 0.969 0.279 --- 0. 69
4 0.33 5. 40 0.969 0.279 --- 0. 69
5 0.42 5.70 1.023 0.279 --- 0.74
6 0.50 6. 40 1. 148 0.279 --- 0.87
7 0.58 7. 90 1.417 0.279 --- 1.14
8 0. 67 9. 10 1. 633 0.279 --- 1.35
9 0.75 12.80 2.297 0.279 --- 2.02
10 0.83 25. 60 4.593 0.279 --- 4.31
11 0. 92 7 . 90 1.417 0.279 --- 1.14
12 1.00 4 . 90 0.879 0.279 --- 0.60
Sum = 100.0 Sum = 14.6
Flood volume = Effective rainfall 1.22 (In)
times area 355.0 (Ac. ) /[ (In) / (Ft. ) ] = 36.0 (Ac.Ft)
Total soil loss = 0.28 (In)
Total soil loss = 8.266(Ac.Ft)
Total rainfall = 1.50 (In)
Flood volume = 1566707.4 Cubic Feet
Total soil loss = 360048.8 Cubic Feet
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Peak flow rate of this hydrograph = 731. 992 (CFS)
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++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 - H O U R S T O R M
R u n o f f H y d r o g r a p h
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Hydrograph in 5 Minute intervals ( (CFS) )
--------------------------------------------------------------------
Time (h+m) Volume Ac.Ft Q(CFS) 0 200.0 400.0 600.0 800.0
-----------------------------------------------------------------------
0+ 5 0. 0423 6.14 Q I I I I
0+10 0.9484 29. 92 VQ I I I I
0+15 0.7970 79. 66 V Q I I I I
0+20 1. 6878 129.35 IV Q I I I I
0+25 2.8222 164.71 1 V Q I I I
0+30 4 . 1569 193.79 1 V QI I I
0+35 5. 6889 222.45 1 V IQ I I
0+40 7 .5047 263. 66 1 V I Q I I
0+45 9.7502 326.04 1 V Q I I
0+50 12.7614 437.23 1 1 V IQ I
0+55 16. 9016 601.16 1 1 V I Q
1+ 0 21. 9429 731.99 i I V I Q
1+ 5 26.2672 627.89 1 I 1 VIQ
1+10 29.0661 406.40 1 1 Q I V
1+15 30.8894 264 .73 1 1 Q I I V
1+20 32. 1143 177.86 1 Q I I I V
1+25 33.0183 131.27 I Q I I I V I
1+30 33.7006 99.06 I Q I I I V
1+35 34.2184 75.20 1 Q I I I V
1+40 34. 6073 56.46 1 Q I I I V
1+45 34 .8940 41. 63 1 Q I I I V
1+50 35.1221 33.13 IQ I I I VI
1+55 35.3103 27.33 IQ I I I VI
2+ 0 35.4631 22.18 IQ I I I VI
2+ 5 35.5914 18. 64 Q I I I VI
2+10 35. 6963 15.24 Q I I I VI
2+15 35.7781 11.88 Q I I I VI
2+20 35.8411 9.15 Q I I I VI
2+25 35.8884 6.87 Q I I I VI
2+30 35.9268 5.57 Q I I I VI
2+35 35. 9555 4.17 Q I I I VI
2+40 35. 9638 1.20 Q I I I VI
2+45 35. 9667 0.42 Q I I I V
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i
U n i t H y d r o g r a p h A n a l y s i s
Copyright (c) CIVILCADD/CIVILDESIGN, 1989 - 1999, Version 6.0
Study date 03/02/05 File: eula1100.out
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
------------------------------------------------------------------------
Riverside County Synthetic Unit Hydrology Method
RCFC & WCD Manual date - April 1978
Canty Engineering Group, Riverside, CA - SIN 693
---------------------------------------------------------------------
English (in-lb) Input Units Used
English Rainfall Data (Inches) Input Values Used
English Units used in output format
---------------------------------------------------------------------
--------------------------------------------------------------------
Drainage Area = 379.00 (Ac. ) = 0.592 Sq. Mi.
Length along longest watercourse = 8000.00 (Ft. )
Length along longest watercourse measured to centroid = 3800.00 (Ft. )
Length along longest watercourse = 1.515 Mi.
Length along longest watercourse measured to centroid = 0.720 Mi.
Difference in elevation = 920.00 (Ft. )
Slope along watercourse = 607.2000 Ft. /Mi.
Average Manning's 'N' = 0.030
Lag time = 0.220 Hr.
Lag time = 13.21 Min.
250 of lag time = 3.30 Min.
400 of lag time = 5.28 Min.
Unit time = 5.00 Min.
Duration oftstorm = 1 Hour(s)
User Entered Base Flow = 0.00 (CFS)
2 YEAR Area rainfall data:
Area (Ac. ) [1] Rainfall (In) [2] Weighting[1*2]
379.00 0. 60 227 .40
100 YEAR Area rainfall data:
Area (Ac. ) [1] Rainfall (In) [2] Weighting[1*2]
379.00 1.50 568 .50
STORM EVENT (YEAR) = 100.00
Area Averaged 2-Year Rainfall = 0. 600 (In)
Area Averaged 100-Year Rainfall = 1.500 (In)
Point rain (area averaged) = 1.500 (In)
Areal adjustment factor = 99. 66 %
Adjusted average point rain = 1.495 (In)
Sub-Area Data:
Area (Ac. ) Runoff Index Impervious %
379.000 77.00 0.000
Total Area Entered = 379.00 (Ac. )
RI RI Infil. Rate Impervious Adj . Infil. Rate Area% F
AMC2 AMC-2 (In/Hr) (Dec.%) (In/Hr) (Dec. ) (In/Hr)
77.0 77.0 0.279 0.000 0.279 1.000 0.279
Sum (F) = 0.279
Area averaged mean soil loss (F) (In/Hr) = 0.279
Minimum soil loss rate ( (In/Hr) ) = 0.140
(for 24 hour storm duration)
Soil low loss rate (decimal) = 0. 900
Slope of intensity-duration curve for a 1 hour storm =0.4800
----------------------------------------------------------------------
U n i t H y d r o g r a p h
Combination of 'S' Curves:
VALLEY 'S' Curve Percentage = 50. 00
FOOTHILL 'S' Curve Percentage = 50.00
MOUNTAIN 'S' Curve Percentage = 0.00
DESERT 'S' Curve Percentage = 0.00
--------------------------------------------------------------------
Unit Hydrograph Data
---------------------------------------------------------------------
Unit time period Time % of lag Distribution Unit Hydrograph
(hrs) Graph % (CFS)
---------------------------------------------------------------------
1 0.083 37.847 3.459 13.213
2 0. 167 75. 694 13.372 51.075
3 0.250 113.540 26. 634 101.732
4 0.333 151.387 21. 652 82.702
5 0. 4k7 189.234 9.837 . 37.574
6 0.500 227.081 6.269 23. 946
7 0. 583 264. 928 4 .534 17.318
8 0. 667 302.774 3. 442 13.148
9 0.750 340.621 2.570 9.815
10 0. 833 378.468 1. 967 7.511
11 0. 917 416.315 1. 421 5.427
12 1.000 454 .162 0. 918 3.506
13 1.083 492.008 0.787 3.006
14 1. 167 529.855 0. 686 2. 621
15 1.250 567.702 0.531 2.027
16 1.333 605.549 0. 496 1.894
17 1. 417 643.396 0.396 1.512
18 1.500 681.242 0.302 1.153
19 1.583 719.089 0.229 0. 873
20 1. 667 756. 936 0.189 0.723
21 1.750 794.783 0. 189 0.723
22 1.833 832.629 0.121 0.461
Sum = 100.000 Sum= 381. 961
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I Unit Time Pattern Storm Rain Loss rate (In./Hr) Effective
(Hr. ) Percent (In/Hr) Max I Low (In/Hr)
1 0.08 4 .40 0.789 0.279 --- 0.51
2 0.17 4.50 0.807 0.279 --- 0.53
3 0.25 5.40 0. 969 0.279 --- 0. 69
4 0.33 5.40 0. 969 0.279 --- 0. 69
5 0.42 5.70 1.022 0.279 --- 0.74
6 0.50 6.40 1.148 0.279 --- 0. 87
7 0.58 7. 90 1. 417 0.279 --- 1.14
8 0.67 9.10 1. 632 0.279 --- 1.35
9 0.75 12.80 2.296 0.279 --- 2.02
10 0.83 25. 60 4.592 0.279 --- 4 .31
11 0.92 7. 90 1.417 0.279 --- 1. 14
12 1.00 4 . 90 0.879 0.279 --- 0. 60
Sum = 100.0 Sum = 14 .6
Flood volume = Effective rainfall 1.22 (In)
times area 379.0 (Ac. ) / [ (In) / (Ft. ) ] = 38.4 (Ac.Ft)
Total soil loss = 0.28 (In)
Total soil loss = 8.824 (Ac.Ft)
Total rainfall = 1.49(In)
Flood volume = 1672176. 9 Cubic Feet
Total soil loss = 384390.1 Cubic Feet
--------------------------------------------------------------------
Peak flow rate of this hydrograph = 791.458 (CFS)
--------------------------------------------------------------------
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 - H O U R S T 0 R M
R u n o f f H y d r o g r a p h
--------------------------------------------------------------------
Hydrograph in 5 Minute intervals ( (CFS) )
--------------------------------------------------------------------
Time (h+m) Volume Ac.Ft Q(CFS) 0 200.0 400.0 600.0 800.0
-----------------------------------------------------------------------
0+ 5 0.0464 6.74 Q I I I
0+10 0.21739 33.03 VQ I I I
0+15 0.8799 87. 98 V Q I I I I
0+20 1.8458 140.25 IV Q I I I I
0+25 3.0719 178.04 I V Q I I I I
0+30 4 .5093 208.70 I V Q I I I
0+35 6.1587 239.49 I V IQ I I I
0+40 8.1160 284.20 ( V I Q I I I
0+45 10.5390 351.82 I V Q I I I
0+50 13.7924 472.40 I 1 V I Q I I
0+55 18.2806 651. 68 I I VI I Q I
1+ 0 23.7314 791.46 1 I 1 V I QI
1+ 5 28 .2925 662.27 1 I 1 VI Q I
1+10 31.2348 427.22 1 I IQ I V I
1+15 33.1432 277.10 1 1 Q I I V 1
1+20 34 .4251 186.13 1 QI I I V I
1+25 35.3702 137.22 I Q I I I V 1
1+30 36.0785 102.85 I Q i I I V I
1+35 36.6142 77.78 I Q I I I V I
1+40 37.0124 57.82 1 Q I I I V I
1+45 37.3061 42.65 1 Q I I I V I
1+50 37.5423 34.29 IQ I I I VI
1+55 37.7359 28.10 IQ I I I VI
2+ 0 37.8931 22.83 IQ I I I VI
2+ 5 38.0249 19.14 Q I I I VI
2+10 38 .1296 15.20 Q I I I V1
2+15 38.2108 11.80 Q I I I VI
2+20 38.2724 8.95 Q I I I VI
2+25 38.3199 6.89 Q I I I VI
2+30 38 .3570 5.40 Q I I I VI
2+35 38.3794 3.25 Q I I I VI
2+40 38 .3860 0.96 Q I I I VI
2+45 38.3879 0.28 Q I I I V
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