Project Name: <br />Project Address <br />Designer: <br />Company: <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 />Oakleigh Meadows Cohousing <br />Oakleigh Lane <br />Eugene. OR 97402 <br />Michael A Cox <br />SSW Engineeers Inc. <br />. Date: 3/1112013 <br />Permit Number: <br />Catchment ID: Rain Garden 8 <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 />Design Requirements: <br />Choose "Yes" from the dropdown 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 facility must be chosen as the facility type to meet destination requirements <br />Data-Post <br />Total Square Footage Impervious Area= 2901 sgft Total Square Footage Pervious Area=~sgft <br />Impervious Area. Cl 98 Pervious Area CN= 85 <br />Total Square Footage of Drainage Area= 2901 sft Time 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 a) Destination Design= in/hr <br />Design Soil Infiltration Rate= 2.5 in/hr Soil Infiltration Rate <br />n Storms Used For Calculations <br />Requirement <br />Rainfall Depth <br />Design Stone <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 />Data <br />Facility Type= <br />Filtration Rain Garden _ J Facility Surface Area= <br />259 <br />sqft <br />Surface Width= <br />7 <br />ft Facility Surface Perimeter- <br />88 <br />ft <br />Surface Length= <br />37 <br />ft Facility Bottom Area= <br />136 <br />sqft <br />Facility Side Slopes= <br />3 <br />to 1 Facility Bottom Perimeter- <br />76 <br />It <br />Max. Ponding Depth <br />in Stormwater Facility= <br />6 <br />in Basin' Volume= <br />101.0 <br />cf <br />I <br />Depth of Growing Medium (Soil)=l <br />18 <br />in Ratio of Facility Area to Impervious Area= <br />0.089 <br />3/11/2013-10:56 AM 11 421 <br />