z-7/S-Z_ <br />Stormwater Surface Filtration/Infiltration Facility Sizing Spreadsheet <br />24 Hour Storm, N RCS Type 1A Rainfall Distribution <br />City of Eugene <br />Version 2.1 <br />Project Name: Oakleiah Meadows Cohousing Date: 1113 12013 <br />Project Address: Oaklelgh Lane Permit Number: <br />Eugene. OR 97402 Catchment ID: Rain Garden 14 <br />Designer-, Michael ACox <br />-ompany: SSW En-cineeers Inc. <br />Instructions: <br />1. Complete this form for each drainage catchment i n the project site that is to be sized per the Presumptive Approach. <br />2. Provide a distinctive Catchment ID fore a ch 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 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 dropdowti 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 racrlity must be chosen as the racilitytype to meet destination requirements <br />Site Data-Post Development <br />Total Square Footage Impervious Area= 2834 sgft Total Square Footage Pervious Area=~sgft <br />Impervious Area CN= 98 Pervious Area CN= 85 <br />Total Square Footage of Drainage Area= 2834 sft Time of Concentration Post Development=min <br />Weighted Average Ct 98 <br />Site Dafa-Pre Development .(Data in-this sectiorils only used if <br />Pre-Development CN= 85 <br />Soil Data <br />Tested Soil Infiltration Rate= 2.5 in/hr (See Note 4) <br />Design Soil Infiltration Rate= 2.5 in/hr <br />Design.Stofms Used For Calculatluris <br />Requirement <br />Rainfall De th <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 />Flow. Control is.requirecO . <br />Time of Concentration Pre-Development= 10 mIn <br />Destination Design= in/hr <br />Soil Infiltration Rate <br />Facility Type= Filtration Rain Garden Facility Surface Area= 240 sgft <br />Surface Width= 10 ft Facility Surface Perimeter= 68 ft <br />Surface Length= 24 ft Facility Bottom Area= 147 sqft <br />Facility Side Slopes= 3 to 1 Facility Bottom Perimeter= 56 ft <br />Max. Ponding Depth <br />in Stormwater Facility= 6 in Basin Volume= 99.0 cf <br />Depth of Growing Medium (Soii)= 18 in Ratio of Facility Area to Impervious Area= 0.085 <br />3/1112013-10:57 AM <br />1 605- <br />