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Home My WebLink AboutMS 04-05; LBC CONDOMINIUM PROJECT; DRAINAGE STUDY; 2006-11-13. DRAINAGE STUDY COVE DRIVE, CARLSBAD . •. November 13, 2006 ReviSed February 6, 2007 PREPARED FOR: . Jerzy & Jolanta Léwák • .4954 Sun Valley. Road . Del Mar, CA 92014 .• • .. .. •t" Job No. 141-04 .• OSIO Kim L. Post, R.C.E. 23166 CD • . -. Vista Engineering,. Inc. 241 930 Vista Village Drive' - Vista, California 92084-6064 IV . . Al (760) 941-2271 - Office . . • (760) 941-7928 Fax ... • • DRAINAGE STUDY LOT 31, COVE DRIVE, CARLSBAD SITE DESCRIPTION & CONCLUSIONS: The subject property is a nearly level dirt lot with virtually no vegetation. The northeasterly end of the property slopes down to the waterline of the Agua Hedionda Lagoon at an approximately 2:1 slope which is armored with riprap. There are no existing structures on the property. The project vicinity is characterized by multi-family residences or vacation residences on narrow lots extending between Cove Drive and the lagoon. There is no drainage basin tributary to the site since Cove Drive drains southeasterly and not onto the site. Additionally the properties on either side of the site can drain to the lagoon directly. A portion of the property southeast of the site drains northeasterly across a sidewalk between the building and-the property line. Although this flow path has sufficient capacity, presently there is nothing to constrain the flow at the property !ine so it is allowed to enter the subject site. The proposed improvements (a wall along the property line) will prevent this cross-lot drainage without obstructing the designed flow path of the neighboring lot. Minor increases in runoff quantities due to proposed impervious surfaces are not a concern since the site drains directly to the Agua Hedionda Lagoon which is connected to the Pacific Ocean. Water quality protections are proposed within the storm drain system. RUNOFF: Using the Rational Method from the County of San Diego Hydrology Manual, June 2003, the Q100 rainfall runoff from the site is calculated using the equation: = Ci 0 A With iloo = 6.9 iph from the Intensity-Duration Design Chart (CountyFigure 3-1) and the 100 year 6 hour and 24 hour Rainfall IsoplUvial maps, and the runoff coefficient C = 0.71 (for HDR, 24 DU/A or less in County Table 3-1) for Soil Type '0': Runoff from the Northwest V2 Site: Q100 = Ci1 A = (0.71)(6.9)(0.05) = 0.25 cfs Runoff from the Southeast % Site:, Q100 = Ci100 A = (0.71)(6.9)(0.05) = 0.25 cfs VISTA ENGINEERING, INC. /R.B. HILL & ASSOCIATES, INC. 930 Vista Village Drive, Vista, California 92084 CIVIL ENGINEERING AND LAND SURVEYING (760) 941-2271 9 Fax (760) 941-7928 HYDRAULICS: The proposed storm drain piping system consists of a 6" PVC main line on. each side of the property that small yard drains and roof drains will connect to which conveys runoff through a filtration box and into the lagoon (see grading plan). The 6" PVC has been designed with a minimum slope of 0.50%. Per the following worksheet, 6" PVC at this slope is able to convey 0.40 cfs which exceeds the runoff from either half of the site calculated above: The filter in the filtration box is able to treat 0.90 cfs per the manufacturers specifications which also exceeds the calculated flow. The adjacent half of property southeast of the site drains to the lagoon as described above. The basin tributary to this flow is estimated to be the same as size and shape as either of the two basins of the subject site, and therefore has a Q100 of approximately 0.25 cfs. According to the attached worksheet, this would result in a depth of flaw of 0.06 feet, keeping the water surface well below the existing condo's finish floor. VISTA ENGINEERING, INC. 1KB. HILL & ASSOCIATES, INC. 930 Vista Village Drive, Vista, California 92084 CIVIL ENGINEERING AND LAND SURVEYING (760) 941-2271 • Fax (760) 941-7928 6" PVC Worksheet for Circular Channel Project Description Project File z:\jobs\2004\141-04\docs\drainage.fm2 Worksheet 6" PVC Flow Element Circular Channel Method Manning's Formula Solve For Full Flow Capacity Input Data Mannings Coefficient 0.013 Channel Slope 0.005000 ft/ft Diameter 6.00 in Results Depth 0.50 ft Discharge 0.40 cfs Flow Area 0.20 ft2 Wetted Perimeter 1.57 ft Top Width 0.00 ft Critical Depth 0.32 ft Percent Full 100.00 Critical Slope 0.009106ft/ft Velocity 2.02 ft/s Velocity Head 0.06 ft Specific Energy FULL ft Froude Number FULL Maximum Discharge 0.43 cfs Full Flow Capacity 0.40 cfs Full Flow Slope 0.005000 ft/ft 09/11/06 FlowMaster v5.15 05:09:28 PM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755-1666 Page 1 of 1 Southeast Offsite Sideyard Worksheet for Trapezoidal Channel Project Description Project File z:\jobs\2004\141-04\docs\drainage.fm2 Worksheet Southeast Offsite Sideyard Flow Element Trapezoidal Channel Method Manning's Formula Solve For Channel Depth Input Data Mannings Coefficient 0.013 Channel Slope 0.005000 ft/ft Left Side Slope 0.010000 H: V Right Side Slope 0.010000 H: V Bottom Width 3.70 ft Discharge 0.25 cfs Results Depth 0.06 ft Flow Area .0.21 ft2 Wetted Perimeter 3.81 ft Top Width 3.70 ft Critical Depth 0.05 ft Critical Slope 0.006840 ft/ft Velocity 1.18 ft/s Velocity Head 0.02 ft Specific Energy 0.08 ft Froude Number 0.87 Flow is subcritical. 01/02107 FlowMaster v5.15 03:42:58 PM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755-1666 Page 1 of 1 w 0 w > 0 C.) 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JA) IIO1- Undisturbed Natural Terrain (Natural) Low Density Residential (LDR) Low Density Residential (LDR) Low Density Residential (LDR) Medium Density Residential (MDR) Medium Density Residential (MDR) Medium Density Residential (MDR) Medium Density Residential (MDR) High Density Residential (HDR) High Density Residential (HDR) Commercial/Industrial (N. Corn) Commercial/Industrial (G. Corn) Commercial/Industrial (O.P. Corn) Commercial/Industrial (Limited I.) Commercial/Industrial (General I) Permanent Open Space Residential, 1.0 DU/A or less Residential, 2.0 DU/A or less Residential, 2.9 DU/A or less Residential, 4.3 DU/A or less Residential, 7.3 DU/A or less Residential, 10.9 DU/A or less Residential, 14.5 DU/A or less Residential, 24.0 DU/A or less Residential, 43.0 DU/A or less Neighborhood Commercial General Commercial Office Professional/Commercial Limited Industrial General Industrial San Diego County Hydrology Manual Section: 3 Date: June 2003 Page: 6 of 26 Table 3-1 RUNOFF COEFFICIENTS FOR URBAN AREAS Land Use Runoff Coefficient "C" Soil Type NRCS Elements County Elements % IMPER. A B C D 0 0.20 0.25 0.30 0.35 10 0.27 0.32 0.36 0.41 20 0.34 0.38 0.42 0.46 25 0.38 0.41 0.45 0.49 30 0.41 0.45 0.48 0.52 40 0.48 0.51 0.54 0.57 45 0.52 0.54 0.57 0.60 50 0.55 0.58 0.60 0.63 65 0.66 0.67 0.69 80 0.76 0.77 0.78 0.79 80 0.76 0.77 0.78 0.79 85 0.80 0.80 0.81 0.82 90 0.83 0.84 0.84 0.85 90 0.83 0.84 0.84 0.85 95 0.87 0.87 0.87 0.87 The values associated with 0% impervious may be used for direct calculation of the runoff coefficient as described in Section 3.1.2 (representing the pervious runoff coefficient, Cp, for the soil type), or forareas that will remain undisturbed in perpetuity. Justification must be given that the area will remain natural forever (e.g., the area is located in Cleveland National Forest). DU/A = dwelling units per acre NRCS =National Resources Conservation Service 3-6 S ( IIj F ico YEAR /?-it Ho uC< /,4f/lLL MAP fiZô,i coo,-Jr( 01 54,-J JE?O 0YD(2oLo4:-Y ,W4U4 jlj f44-6q- )I Flo-Gard Filter installed ModpJ No. Inlet 1.0. Grate'O.D. Solids Storage Cam (cu ft) RI ROW .(cfs). Total Bypass Cap.( FF-V64D .14" x 14" .16"x 16" 0.3 0.5 0.2 FF-16D .16" x 16" .18" x 18" 0.5 0.8 0.4 FF-16240 .16°x24° .16"x26" 0.6 1.1 0.6, FF-18D .18"x 18" .20"x 20" 0.5 0.9 0.5 FF-1824D .18"x24" 20°x24" 0.6 .1.1 0.6 .FF-1836SD .18" x 36" 18"x 40" .1.0 .1.7 1.1 FF-18361)G0 .18"x36" .18" x 40" .1.0 1.7 1.1 FF-1848DG0 48° x 48" .18" x 52° .1.2 2.1 .1.4 FF-21 D .22" x 22" .24" x 24° 0.7 . .1.2 0.7 FF-24D .24" x 24° .26"x 26" 0.8 .1.4 0.9 FF-240G0 24" x 24" .18" x 36" 0.8 .1.4 0.9 FF-2430D .24" x 30" 26" x 30° .1.0 .1.7 1.1 FF-2436D .24" x 36° 24" x 40° .1.1 .1.9 1.3 FF-24360G0 .24" x 36" 24" x 40" .1.1 .1.9 .1.3. FF-2448D(c) . 24" x 48" 26°x 48" .1.3 ' ' 2.3 . .1.6 FF-30D 30" x 30 30"x 34°. 1.1 .1.9 .1.3 FF-36D(2pc) .36° x 36° 36' x 40" 1.3 2.3 1.6 FF-3648D(c) . 36" X 48" 40" x 40" 1.6 2.7 1.9 FF-48D (2 lx) 48" x 48" .48° x 52" ..1.8 3.2 2.3 .1. Storapcopacity reflects 80% of nimimi solids collection prior to bypass. Rftered flow rate Includes a safety factor 012. RoGardldi Basin Alter Inserts sie available In the s1a.d shes (see above) or In customslses. iI for details on custom cia Insects. A 'AoGafllter Inserts should be used In conjunction 1th a regular neInte.iw program. Refer to nenutacture?s .,......dedmaintmo, guidelines. US PATENT .FLOGARD9 CATCH BASIN ALTER INSERT (Frame Mount) FLAT GRATED INLET KtlStar Enterprises, Inc., Santa Rosa CA (800) 579-8819