HomeMy WebLinkAboutDrainage Report DRAINAGE /PROJECT REPORT
Carmel Office Park
Buidling Addition A.
Gradle Drive 3 Street C. s
Carmel, IN i v.: Q.
December 8, 2009 t� t
O
INTRODUCTION:
This project consists of constructing 2,000 square foot building addition to an existing
office /warehouse building within the Carmel Office Park. The office /warehouse is located in
southeast corner of Carmel Office Park and is located along Summit Drive with said park. The
rear or east side of the existing building abuts an existing storage unit/office complex. The
proposed area of expansion consist of grass surface.
EXISTING CONDITIONS:
An existing detention basin is shared by the Carmel Office Park and the east adjoining property.
The pond is located at the east side of proposed addition area and collects water from the existing
building, rear asphalt parking area, the existing buildings and rear drive areas of the east
adjoining development a drainage map is included for clarification. The release structure of the
existing detention pond is a concrete inlet with a 10" orifice located at the flow line of the
existing pond. The release structure is then connected to the City's infrastructure system via a
15" RCP.
Site soil is classified as Miami Silt Loam (MmC2). None of the site lies within the a Flood
Hazard Zone
PROPOSED CONDITIONS:
The proposed development will release the storm water runoff from the 2,000 square foot
expansion via downspout and will be retained as part of the existing detention system. Minor
earth grading and re- seeding around the proposed expansion will occur.
DATA AND COMPUTATIONS:
The attached hydrographs were created to include the proposed addition area as impervious
surface and to prove the conversion from grass area to roof surface will not overburden the
existing detention facility. detention basin allowable release rate was calculated using the SCS
method as shown in the attached data.
1 0 8
Hydrograph Summary Report Hydrographs Extension for AutoCAD® Civil 3D® 2009 by Autodesk, Inc. v6.066
Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph
No. type flow interval peak volume hyd(s) elevation strge used description
(origin) (cfs) (min) (min) (cuft) (ft) (cuft)
1 Rational 9.896 1 5 2,969 Build Add
2 Reservoir 3.663 1 8 2,969 1 838.02 1,495 Detention Release
Rational.gpw Return Period: 100 Year Tuesday, Dec 8, 2009
9
Hydrograph Repo
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2009 by Autodesk, Inc. v6.066 Tuesday, Dec 8, 2009
Hyd. No. 1
Build Add
Hydrograph type Rational Peak discharge 9.896 cfs
Storm frequency 100 yrs Time to peak 5 min
Time interval 1 min Hyd. volume 2,969 cuft
Drainage area 1.310 ac Runoff coeff. 0.78*
Intensity 9.685 in /hr Tc by User 5.00 min
IDF Curve indianapolis.IDF Asc /Rec limb fact 1/1
Composite (Area /C) [(1.020 x 0.90) (0.290 x 0.35)] 1.310
Build Add
Q (cfs) Hyd. No. 1 100 Year Q (cfs)
10.00 10.00
8.00 8.00
6.00 6.00
4.00 4.00
2.00 2.00
0.00 0.00
0 1 2 3 4 5 6 7 8 9 10
Hyd No. 1 Time (min)
10
Hydrograph Repo
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2009 by Autodesk, Inc. v6.066 Tuesday, Dec 8, 2009
Hyd. No. 2
Detention Release
Hydrograph type Reservoir Peak discharge 3.663 cfs
Storm frequency 100 yrs Time to peak 8 min
Time interval 1 min Hyd. volume 2,969 cuft
Inflow hyd. No. 1 Build Add Max. Elevation 838.02 ft
Reservoir name Exist Pond Max. Storage 1,495 cuft
Storage Indication method used.
Detention Release
Q (cfs) Hyd. No. 2 100 Year Q (cfs)
10.00 10.00
8.00
A
6.00 6.00
4.00 4.00
2.00 2.00
0.00 0.00
0 2 4 6 8 10 12 14 16 18 20 22
Time (min)
Hyd No. 2 Hyd No. 1 11 1 1 1 11 1] Total storage used 1,495 cuft
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