3/~ L~ <br />Project Name: <br />Project Address: <br />Designer: <br />Company: <br />Stormwater Surface Filtration/Infiltration Facility Sizing Spreadsheet <br />24 Hour Stortrt, NRCS Type 1A Rainfall Distribution <br />City of Eugene <br />Version 2.1 <br />Qakleigh Meadows Cohousincl <br />Oaklelah Lane <br />Eugene, OR 97402 <br />Michael A Cox <br />SSW E=n ineeers Inc. <br />Date: 3/1112013 <br />Permit Number:. <br />Catchment ID: Rain Garden 2 <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 inthr. <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 />I Pollution Reduction (PR) Yes <br />Flow Control (FC) Yes <br />Destination (DT) NO 'M Infiltration facility must be chosen as the facility type to meet desllnation requirements <br />Site Data-Post Development <br />Total Square Footage Impervious Area= 1969 sqft Total Square Footage Pervious Area= sgft <br />Impervious Area CN= 98 Pervious Area CN= 85 <br />Total Square Footage of Drainage Area= 1969 sit Time of Concentration Post Development- min <br />Weighted Average CN= 98 <br />Site Dai:a-Pre Development (Data in this section is only used If Flow Control is. required) <br />Pre-Development CN= = Time of Concentration Pre-Development= 10 min <br />Solt Data <br />Tested Sol[ Infiltration Rate= 2.5 in/hr (see Note4) <br />Design Soil Infiltration Rate= 2.5 in/hr <br />s-Used For Calculations <br />Requirement <br />Rainfall Depth <br />Desl n Storm <br />Pollution Reduction <br />1.4 <br />inches <br />Water Qpality <br />Flow Control <br />3.6 <br />inches <br />Flood Control <br />Destination <br />3.61 <br />inches <br />Flood Control { <br />Destination Design= in/hr• <br />Soil Infiltration Rate <br />t?aciti~_Data.. _ - • - _ . r <br />Facility Type= Filtration Rain Garden Facility Surface Area= 192 sgft <br />Surface Width= 6 ft Facility Surface Perimeter= 76 ft <br />Surface Length= 32 ft Facility Bottom Area= 87 sgft <br />Facility Side Slopes= 3 to 1 Facility Bottom Perimeter= 64 ft <br />Max. Ponding Depth <br />in Stormwater Facility= 6 in' Basin Volume= 72.0 cf <br />Depth of Growing Medium (Soil)=L____ 18 in Ratio of Facility Area to Impervious Area= 0.098 <br />3/11/2013-10:54 AM 1 581 <br />