Z313-z <br />Stormwater Surface Filtration/Infiltration Facility Sizing Spreadsheet <br />24 Hour Storm, NRCS Type 1A Rainfall Distribution <br />City of Eugene. <br />Version 2.1 <br />Project'lnformatlon <br />Project Name: Oaklelh Meadows Cohousinq Date: 3111/2013 <br />Project Address: Oaklejgh Lane Permit Number: <br />OR 97402 Catchment ID: Rain G r~12 <br />Eugene <br />Designer: Michael A Cox <br />Company SSW Bn ineeers 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 thisfacility <br />Pollution Reduction (PR) Yes <br />Flow Control (FC) Yes <br />Destination(DT) No -An infiltration facility must be chosen as the facility type to meet destinationrequirements <br />IS.Ite Data-Post Development <br />Total Square Footage Impervious Area= 1349 sgft Total Square Footage Pervious Aread -0 <br />Impervious Area CN- 98 Pervious Area-CN- 85 <br />Total Square Footage of Drainage Area= 1349 sft Time of Concentration Post Development===5 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= 65 Time of Concentration Pre-Development= 10 min <br />ISoil Data <br />Tested Soil Infiltration Rate= 2.5 In/hr (see Note) Destination Design= in/hr <br />Design Soli Infiltration Rate= 2.5 Whir Soil Infiltration Rate <br />IDesign Storms-Used.For Calcytations <br />Requirement <br />Rainfall Depth <br />Design Storm <br />Pollution Reduction <br />1.41inches _ <br />WaterQuallt~r <br />Flow Control <br />3.6 inches <br />Flood Control <br />Destination <br />3.6 inches <br />Flood Control <br />I <br />Facflitst Data - - <br />- _ _ <br />Facility Type= Filtration Rain Garden <br />Facility Surface Area= 126 sqft <br />Surface Width={ 6 <br />ft . <br />Facility Surface Perimeter=1 54 it <br />Surface Length=i 21 <br />it <br />Facility Bottom Area=1 54 sqft <br />Facility Side Slopes= 3 <br />to 1 <br />Facility Bottom Perimeter=1 42 ft <br />Max. Ponding Depth <br />l <br />- <br />~ <br />in Stormwater Facility= 6 <br />18 <br />D <br />th of Growin <br />Medium Soil= <br />LL <br />in ~ <br />in <br />Basin Volume= <br />47.2 cf <br />Ratio of Facilit <br />Area to Impervious Area= 0 <br />093 <br />ep <br />g <br />y <br />. <br />. <br />3/11 /2013-10:56 AM 1 601 <br />