s/-~,-i <br />Stormwater 5urface 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: 3/1112013 <br />Project Address: Oakleioh Lane Permit Number: <br />Eugene, OR 97402 Catchment ID: Rain Garden 3 <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 map to 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 facuTdy type to meet destination requirements <br />Site Data-Post Development <br />Total Square Footage Impervious Area= 1854 sgft Total Square Footage Pervious Area=sgft <br />Impervious Area CN= 98 <br />Pervious Area CN= 85 <br />Total Square Footage of Drainage Area= 1854 sft Time of Concentration Post Development-- min <br />Weighted Average CN= 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 />Desi <br />n S <br />il I <br />f <br />lt <br />ti <br />R <br />t <br />= <br />g <br />o <br />ra <br />n <br />i <br />on <br />a <br />e <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 />Water Quality <br />Flow Control <br />3.6 <br />inches <br />Flood Control <br />Destination <br />3.6 <br />inches <br />Flood Control <br />Faciliti-Data... <br />Facility Type= <br />Filtration Rain Garden Facility Surface Area= <br />180 <br />sgft <br />Surface Width= <br />6 <br />ft Facility Surface Perimeter- <br />72 <br />ft <br />Surface Length= <br />30 <br />ft Facility Bottom Area= <br />81 <br />sgft <br />Facility Side Slopes= <br />3 <br />to 1 Facility Bottom Perimeter- <br />60 <br />ft <br />Max, Ponding Depth <br />in Stormwater Facility= <br />6 <br />in Basin Volume= <br />67.5 <br />cf <br />Depth of Growing Medium (Soil)= <br />18 <br />in Ratio of Facility Area to Impervious Area= <br />0.097 <br />3/1112013-10:54 AM ' 1 583 <br />