2.° <br />4 <br />F_ <br />L <br />Stormwater Surface Filtration/Infiltration Facility Sizing Spreadsheet <br />.24 Hour Storm, NRCS Type 1A Rainfall Distribution <br />City of Eugene <br />Version,_2.1 <br />Project Information <br />Project Name: Oakleigh Meadows Cohousing Date: 3111/2013 <br />Project Address: Oakleigh Lane Permit Number: <br />Eugene, OR 97402 Catchment ID: Rain Garden 15 <br />Designer: Michael A Cox <br />Company: SSW.Engineeers Inc. <br />Instructions: <br />1. Complete this form for each drainage catchment in the project site that is to be sized per the Presumptive Approach. <br />2. Provide a distinctive Catchment ID for each facility coordinated with the site basin maprto correlate the appropriate <br />calculations with the facility. <br />3. The maximum drainage catchment to be modeled per the Presumptive Approach is 1 acre (43,560 SF) <br />4.For-infiltration facilities in Class A or. B soils where no infiltration testing has been perfromed use an infiltration rate of 0.5 in/hr. <br />For all facilities use a maximum soil infiltration rate of 2.5 in/hr for topsoil/growing medium. <br />Design Requirements: <br />Choose "Yes" from the dropdown boxes below next to the design standards requirements for this facility. <br />Pollution Reduction (PR) Yes <br />Flow Control (FC) Yes. <br />Destination (DT) NO. 'An infiltration facility must be chosen as the facility type to meet destination requirements <br />Site Data-Post Development <br />Total Square Footage Impervious Area= <br />1592 <br />sqft Total Square Footage Pervious Area= 0 sqft <br />Impervious Area CN= <br />98 <br />- Pervious Area CN= 85 <br />Total Square Footage of Drainage Area= <br />1592 <br />sft Time of Concentration Post Development-- min <br />Weighted Average CN= <br />98 <br />Site Data=Pre Development .(Data in this section-is only used if Flow Control is required) <br />Pre-Development CN=. 85 Time of Concentration Pre-Development= 10 min <br />Soil Data . <br />Tested Soil Infiltration Rate= <br />2.5 <br />in/hr (See Note 4) Destination Design= in/hr <br />Design Soil Infiltration Rate= <br />2.5 <br />in/hr Soil Infiltration Rate <br />Design. Storms. Used For Calculations <br />Requirement <br />Rainfall Depth <br />Design Storm <br />Pollution Reduction <br />1.4 <br />inches <br />WaterQual' <br />Flow Control <br />3.6 <br />inches <br />Flood Control <br />Destination <br />3.6 <br />inches <br />Flood Control <br />Facility Data-... - . - - - <br />Facility Type= <br />Filtration Rain Garden Facility Surface Area= <br />147 <br />sgft <br />Surface Width= <br />7 <br />ft Facility Surface Perimeter- <br />56 <br />ft <br />Surface Length= <br />21 <br />ft Facility Bottom Area= <br />72 <br />sgft <br />Facility Side Slopes= <br />3 <br />to 1 Facility Bottom Perimeter- <br />44 <br />ft <br />Max. Ponding Depth <br />in Stormwater Facility= <br />6 <br />in. Basin Volume= <br />57.0 <br />cf <br />Depth of Growing Medium (Soil)= <br />18 <br />in Ratio of Facility Area to Impervious Area= <br />0.092 <br />3!11/2013-10:57 AM <br />607 <br />