Stormwater Surface Filtration/Infiltration Facility Sizing Spreadsheet <br />24 Hour Storm, NRCS Type 1A Rainfall Distribution <br />Cityof Eugene <br />Version 2.1 <br />roject Name:. Oakleigh Meadows Cohousing Date: 3/1112013 <br />roject Address: Oakiei h Lane Permit Number; <br />Eugene, OR 97402 Catchment ID: Rain Garden 7 <br />esigner: Michael A Cox . <br />ompany: SSW Englneeers 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.F or infiltration facilities in ClassA 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 />Choose "Yes"from the dropdown boxes below next to the design standards requirements for this facility. <br />Pollution Reduction (PR) 91-PnInfillralion Flow Control (FC) Destination (DT) facility must be chosen as the facility type to meet desf nation requirements <br />Site Data-Post Development <br />Total Square Footage Impervious Area= <br />2121 <br />sgft Total Square Footage Pervious Area=sgft <br />Impervious Area CN= <br />98 <br />Pervious Area CN= 85 <br />Total Square Footage of Drainage Area= <br />2121 <br />sft Time of Concentration Post Development=min' <br />Weighted Average C1 <br />98 <br />Site Data-Pre Development-" (Data*ln 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= 2.5 <br />Design Soli Infiltration Rate= 2:5 <br />in/hr(see Note4) "Destination Design= 1n1hr <br />In/hr Soil Infiltration Rate <br />Design Storms Used For"Calculafions <br />Requirement <br />Rainfall Depth_ <br />Design Stonn <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 />. . _ . <br />Facilitu"Data_..:. " _ - <br />Facility Type= <br />Surface Width= <br />Surface Length= <br />Facility Side Slopes= <br />Max. Ponding Depth <br />In Stormwater Facility= <br />Depth of Growing Medium (Soil)= <br />Filtration Rain Garden Facility Surface Area= 71789 sgft <br />7 It Facility Surface Perimeter= 68 ft <br />27 It Facility Bottom Area= 96 sgft <br />3 to 1 Facility Bottom Perimeter= 56 It <br />6 in Basin Volume= 73.5 cf <br />l 18 in Ratio of Facility Area to Impervious Area= 0.089 <br />3111/2013-10:55 AM <br />1 591 <br />