HomeMy WebLinkAboutCT 00-06; BRESSI RANCH; BRESSI RANCH MASS GRADING & BACKBONE IMPROVEMENTS; 2004-10-01REFERENCE DRAINAGE REPORT
BRESSI RANCH MASS GRADING &
BACKBONE IMPROVEMENTS
CARLSBAD, CALIFORNIA
CT 00-06
Dwg 400-8A, 400-8C, 400-8D
OCTOBER 2004
Prepared for
LENNAR COMMUNITIES
c/o LENNAR BRESSI VENTURE, LLC
5780 Fleet Street, Suite 320
Carlsbad, CA 92008
Prepared By:
PROJECTDESIGN CONSULTANTS
701 'B' Street, Suite 800
San Diego, CA 92101
(619) 235-6471
Job No. 2244.00
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1.0 REFERENCE
This report is to provide evidence of a previously approved design for the desilting basin at
Planning Area 1 of Bressi Ranch in Carlsbad, Califomia. Please refer to Table 1 and Drainage
Map Exhibit "B" for basin calculations. The desilting basin in Planning Area 1 is indicated as
Basin 411. As you can see, the basin should be designed to maintain 73 CY of debris volume
over its 985 SF of surface area. The desilting basin that was originally designed for Planning
Area 1 has more than exceeded this minimum maintenance volume, which adequately services
Planning Axea 1 for proper storm water desilting. The surface area for the desilting basin was
originally designed at 7,240 SF.
With the introduction of the construction change to Metropolitan Street, the desilting basin will
need to be reconfigured to lie outside of the street right-of-way. This reconfiguration will
slightly reduce the surface area of the desilting basin to 6,836 SF. This area however, continues
to adequately service Planning Area 1 for storm water desilting, as the basin should still need
only to maintain 985 SF of surface area.
BRESi. RANCH RISER DESIGN
TABLE I
Ultimate Riser Debris Surface Outlet Riser Weir
Basin Area Qioo Qioo Volume Area Pipe Pipe Size Ho Widlh
(acres) (CIS) (cfs) (yd") (ft') (inches) (inches) (feet) (feel)
100 17.7 72.4 27.3 492 6642 36 48 0.75 10
106 20.8 79.2 29.7 589 7951.5 36 48 0.8 12
107 11.9 49.9 18.1 329 4441.5 30 42 0.57 6
108 15 69.6 24.6 404 5454 36 48 0.65 10
111 5.2 24.5 9 148 1998 24 36 0.5 6
206 25 N/A 48 944 12744 36 72 0.9 16
207 9.3 17.5 18.6 264 3525 24 36 0.7 6
300 28.5 49.1 38.8 695 9382.5 30 42 1.1 13
408 8.6 41.4 17.3 248 3348 30 42 0.55 6
411 2.2 11.8 5.1 73 985 24 30 0.5 6
808 13 48.9 20.5 344 4644 30 42 0.65 8
1200 12.2 30 22.2 336 4536 24 36 08 8
2001 10.6 44.2 15.7 298 4023 30 42 0.55 6
2011 15.5 55.4 20.9 420 5670 30 42 0.65 8
4000 10.1 26.3 16.6 286 3861 24 36 0.65 6
5025 19.3 N/A 35.2 534 7209 30 42 1.05 12
5036 27.7 N/A 44.3 785 10597.5 30 72 1 20
5037 2.5 N/A 4 71 960 18 30 0.5 6
5050 6.5 13.6 12.3 184 2484 18 30 0.6 6
5074 7.3 N/A 14.3 207 2794.5 18 30 0.7 6
5086 27.4 N/A 52 777 10489.5 30 72 1 18
6000 25.3 58 41.9 896 12096 30 72 1 18
900.5 5.2 N/A 17.9 261 3523.5 24 36 0.7 6
901.5 12 N/A 20.3 332 4482 24 36 0.8 8
902.5 4.5 N/A 7.4 128 1728 18 30 0.5 6
903.5 6.3 22.2 10.7 122 1647 24 36 0.5 6
Notes For Table 1
1
2.
3.
4.
3.
Basin Number shown on Mttss Grading Hydrology Exhibit.
Area is tributary acreage to desilting basin per Mass Grading Plan.
Ultimate Qia, based upon ultimate conditionQ,oo rational calculations.
Riser QIOO based on a clettred and mass graded site using C = 0.55.
Debris volume is from Cily of Carlsbad Capacity Table as shown supplement to DWG No. DS-3 (Temporary Desilting Basin Outlet and Capacity Table).
Tlie capacities are more conservative than the 2-ycar sediment yield calculate using MUSLE.
6. Surface area is desilting basin area assuming 2 feet of sediment deposition.
7. Outlet pipe size based on normal depth calculation using Ultimate Qc for permanent pipes in industrial areas and Riser Q for temporary pipes in residential areas.
8 Riser pipe size calculated using weir equation with the sheet flow discharge (see sample calculations for riser pipe sizing).
9. Ho is the iieight oi ponding above t!ie top of thc riser,
10. Basin depth assumes 2' sediment depth. 2' settling deptii, Ho= 1.0', freeboard = 1,0'. See Riser Design, Table 2 on following page regarding settling deptii.
11. Weir width calculated assuming H = 1.0' (Q = 3,0 LH"^), where Q = QMSER. L = 6' min.
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