Stormwater Surface Filtrationllnfiltration 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: Oakleiiah Meadows Cohousina Date: 3/11/2013 <br />Project Address: Cakleigh Lane Permit Number: <br />Eugene, OR 97402 Catchment ID: Rain Garden 12 <br />Designer: Michael A Cox <br />Company: SSW Enctfneeers 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 />"Yes" from the dropdown boxes below next to the design standards requirements for this facility. <br />I Pollution Reduction (PR) Yes <br />Flow Control (FC) Yes <br />Destination (DT) No *An infiltration facility must be chosen as thefacility type to meet destination requirements <br />Data-Post <br />Total Square Footage Impervious Area= 1349 sgft Total Square Footage Pervious Area=~sgft <br />Impervious Area CN- 98 Pervious Area CN= 85 <br />Total Square Footage of Drainage Area= 1349 sft Tiine 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= 2.5 in/hr (See Note 4) Destination Design= in/hr <br />Design Soil Infiltration Rate= 2.5 in/hr Soil Infiltration Rate <br />Storms Used For Calculations <br />Requirement <br />Rainfa <br />ll 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 />[Facility Data <br />Facility Type= Filtration Rain Garden Facility Surface Area= 126 sgft <br />Surface Width=l 61 ft Facility Surface Perimeter=1 541ft <br />Surface Length=1 21 Ift Facility Bottom Area=1. 541sgft <br />Facility Side Slopes=1 31to 1 Facility Bottom Perimeter=1 421ft <br />Max. Ponding Depth i__jin in Stormwater Facility= Basin Volume= 47.2Icf <br />Depth of Growing Medium (Soil)= 18 in Ratio of Facility Area to Impervious Area= 0.093 <br />3111/2013-10:56 AM <br />11429 <br />