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Home My WebLink AboutStudies APPLICANT 11/17/2020BUDGET BLINDS DRAINAGE STUDY November 17. 2020 SITE CHARACTERISTICS The subject properly is identified on County Assessor's Maps as 17-02-34-41-2502 and 2602. It is located on the south side of A St., east of 58th Sl. The site is an open field and consists of about 0.47 acres. EXISTING HYDROLOGY The site is relatively flat and portions of the site drain to the north. PROPOSED HYDROLOGY The proposed drainage system consists of piping the proposed impervious drainage to two planters located on the north side and west side of the properly. The north basin collects the drainage from the parking spaces and walks on the east side of the building. The planter size was determined using the City of Eugene's Slormwaler Surface Filtration/Infiltration Facility Sizing Spreadsheet. Attached is the spreadsheet. The west basin collects the drainage from the entire building and parking spaces and walks on the south side of the building. The planter size was determined using the City of Eugene's Slormwaler Surface Filtration/Infiltration Facility Sizing Spreadsheet. Attached is the spreadsheet. CONCLUSION Based on my calculations and the proposed drainage system is sized properly and will provide the necessary flow control. ��NP� <v-1'4'0 WOREGON EXPIRES DEC. 31. 2021 ji1j.d.�— Stormwater Surface Filtration/Infiltration Facility Sizing Spreadsheet 24 Hour Storm, NRCS Type 1 A Rainfall Distribution City of Eugene Name: Budget Blinds Address: AStreet 1.4 inches Springfield m Anthony J. Favreau V: The Favreau Group Date: 10/28/2020 Permit Number: Permit Catchment ID: North Basin Complete this form for each drainage catchment in the project site that is to be sized per the Presumptive Approach. Provide a distinctive Catchment ID for each facility coordinated vdth the site basin map to correlate the appropriate calculations with the facility. The maximum drainage catchment to be modeled per the Presumptive Approach is 1 acre (43,560 SF) =or infiltration facilities in Class A or B soils where no infiltration testing has been pertromed use an infiltration rate of OS War. For all facilities use a maximum soil infiltration rate of 2.5 War for topsoil/growing medium. loose "Yes" fmm the dmpdown boxes below next to the design standards requirements for this facility. Pollution Reduction (PR) Yes Flow Control FC)l No Destination(DT) No 'nnim'uo-ation kciiiry must becMsen as o -a txiiiry ttvew rreettlesonation requiremems Total Square Footage Impervious Area=1]85 soft Total Square Footage Pervious A 0 sgfl Impervious Area CN=l 98 Pervious Area CN=l 85 Total Square Footage of Drainage Area= 1785 all Time of Concentration Post Development= OS min Weighted Average CN=l 98 Pre�Development CN= 85 Time of Concentration Pre�Davelopment= 10 min Tested Soil Infiltration Rate= iWhr (See We 4) Destination Design=®in/hr Design Soil Infiltration Rate=1 0]5 iNhr Soil Infiltration Rate R uihe Rainfall De h Dari A Storm Pollution Redugion 1.4 inches Water Qualit Flow Control 3.6 inches Flood Control Destination I 3.6 inches Flood Control Facility Facility Side Slop( Max. Ponding Depth in Stormwater Facility - Depth of Growing Medium (So iDII'I:6'AYAII:1847s14 Facility Sudace Facility Sudace Pern Facility Bottom Facility Bottom Pern Ratio of Facility Area to Basin Vc Pollution Reduction-Calculation Results cfs Peak Flow Rate to Stormwater Facility =q0, Peak Facility Overflow Rate= 0.000 cfs Total Runoff Volume to Stormwater Facility=cf Total Overflow Volume= 0 cf Max. Depth of Stormwater in Facility=in Drawdown Time=hours Yes Facility Sizing Meets Pollution Reduction Standards? VES Meets Requirement of No Facility Flooding? VES Meets Requirement for Maximum of 18 Hour Drawdown Time? Flow Control-Calculation Results Peak Flow Rate to Stormwater Facility = 0.039 cfs Peak Facility Overflow Rate= 0.036 cfs Total Runoff Volume to Stormwater Facility= 500 cf Total Overflow Volume= 192 cf Peak Off -Site Flow Rate Max. Depth of Stormwater in Facility= 6.0 in Filtration Facility Underdrain= 0.003 cfs Drawdown Time= 8.0 hours Pr vekmment R nff Date Peak Flow Rate = 0.021 cfs Total Runoff Volume =1 313 cf =Facility Sizing Meets Flow Control Standards? Nw Meets Requirement for Post Development offsite flow less or equal to Pre-Development Flow? ZI NW Meets Requirement for Maximum of 18 Hour Drawdown Time? Destination-Calculation Results Peak Flow Rate to Stormwater Facility = N/A cfs Peak Facility Overflow Rate= N/A cfs Total Runoff Volume to Stormwater Facility= N/A cf Total Overflow Volume= N/A cf Max. Depth of Stormwater in Facility- N/A in Drawdown Time= N/A lours N/A Facility Sizing Meets Destination Standards? N/A Meets Requirement of No Facility Flooding? L.2LAJMftts Requirement for Maximum of 30 hour Drawdown Time? 1028/2020-8:35 AM Stormwater Surface Filtrationilnfiltration Facility Sizing Spreadsheet 24 Hour Storm, NRCS Type 1 A Rainfall Distribution City of Eugene Name: Budget Blinds Address: AStreet 1.4 inches Springfield m Anthony J. Favreau V: The Favreau Group Date: 10/28/2020 Permit Number: Permit Catchment ID: West Basin 8 BMa Complete this form for each drainage catchment in the project site that is to be sized per the Presumptive Approach. Provide a distinctive Catchment ID for each facility coordinated with the site basin map to co -elate the appropriate calculations with the facility. The maximum drainage catchment to be modeled per the Presumptive Approach is 1 acre (43,560 SF) =or infiltration facilities in Class A or B soils where no infiltration testing has been pertromed use an infiltration rate of OS War. For all facilities use a maximum soil infiltration rate of 2.5 War for topsoil/growing medium. loose "Yes" fmm the dmpdown boxes below next to the design standards requirements for this facility. Pollution Reduction (PR) Yes Flow Control FC)l No Destination(DT) No 'nnim'uo-ation kciiiry must becMsen as o -a txiiiry t -sew rreettlesonation requiremems Total Square Footage Impervious Area=124]9 soft Total Square Footage Pervious A 0 sgfl Impervious Area CN=l 98 Pervious Area CN=l 85 Total Square Footage of Drainage Area= 12479 sfl Time of Concentration Post Development= OS min Weighted Average CN=l 98 Pre�Development CN= 85 Time of Concentration Pre�Davelopment= 10 min Tested Soil Infiltration Rate=m/hr (See We 4) Destination Design=®in/hr Design Soil Infiltration Rate= 1 in/hr Soil Infiltration Rate R uihe Rainfall De h Desi -Storm Pollution Redugion 1.4 inches Water Qualit Flow Control 3.6 inches Flood Control Destination I 3.6 inches Flood Control Facility Facility Side Slop( Max. Ponding Depth in Stormwater Facility - Depth of Growing Medium (So iDII'I:6'AYAII:18h/A4 Facility Sudace Facility Sudace Pern Facility Bottom Facility Bottom Pern Ratio of Facility Area to Basin Vc Pollution Reduction-Calculation Results Peak Flow Rate to Stormwater Facility = 0.097 cfs Pik Facility Overflow Rate= 0.000 cfs Total Runoff Volume to Stormwater Facility 1226 cf Total Overflow Volume= 0 cf Max. Depth of Stormwater in Facility= 4.9 in Drawdown Time= 15 hours Yes Facility Sizing Meets Pollution Reduction Standards? =Meats Requirement of No Facility Flooding? VES Meets Requirement for Maximum of 18 Hour Drawdown Time? Flow Control-Calculation Results Peak Flow Rate to Stormwater Facility = 0.269 cfs Peak Facility Overflow Rate= 0.254 cfs Total Runoff Volume to Stormwater Facility= 3493 cf Total Overflow Volume= 1886 cf Peak Off -Site Flow Rate Max. Depth of Stormwater in Facility= 6.0 in Filtration Facility Underdrain= 0.015 cfs Drawdown Time= 6.0 hours Pre-Development Runoff Data Peak Flow Rate = 0.149 cfs Total Runoff Volume =1 2188 cf =Facility Sizing Meets Flow Control Standards? Nw Meets Requirement for Post Development offsite flow less or equal to Pre-Development Flow? NW Meets Requirement for Maximum of 18 Hour Drawdown Time? Destination-Calculation Results Peak Flow Rate to Stormwater Facility = N/A cfs Peak Facility Overflow Rate= N/A cfs Total Runoff Volume to Stormwater Facility= N/A cf Total Overflow Volume= N/A cf Max. Depth of Stormwater in Facility- N/A in Drawdown Time= N/A lours N/A Facility Sizing Meets Destination Standards? N/A Meets Requirement of No Facility Flooding? L.2LAJMftts Requirement for Maximum of 30 hour Drawdown Time? 1028/2020-8:36 AM