HomeMy WebLinkAboutStudies Applicant 3/29/2024
KINGSLET DRAINAGE STUDY
March 21, 2024
SITE CHARACTERISTICS
The subject property is identified on County Assessor’s Map as 17-03-26-31-900. It is located on the northwest corner of
5th St. and Moffit Lane. The site is an open field an existing home and consists of about 0.49 acres.
EXISTING HYDROLOGY
The site is relatively flat and drains to the west. An infiltration test was performed and an infiltration rate of 5” per was
determined.
PROPOSED HYDROLOGY
The proposed drainage system of piping the proposed drainage to a proposed treatment planter on the north end of the
proposed driveway. The planter was sized using the City of Eugene Stormwater Surface Filtration/Infiltration Facility
Sizing Spreadsheet. (See attached.)
CONCLUSION
Based on my calculations and the proposed drainage systemis sized properly.
Stormwater Surface Filtration/Infiltration Facility Sizing Spreadsheet
24 Hour Storm, NRCS Type 1A Rainfall Distribution
City of Eugene
Version 2.1
Project Information
Instructions:
Design Requirements:
Choose "Yes" from the dropdown boxes below next to the design standards requirements for this facility.
Pollution Reduction (PR)Yes
Flow Control (FC)No
Kinglet CourtProject Name:
1620 5th St.
2. Provide a distinctive Catchment ID for each facility coordinated with the site basin map to correlate the appropriate
calculations with the facility.
3. The maximum drainage catchment to be modeled per the Presumptive Approach is 1 acre (43,560 SF)
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.
For all facilities use a maximum soil infiltration rate of 2.5 in/hr for topsoil/growing medium.
3/20/2024
[Permit #]
Entire Subdivision
Date:
1. Complete this form for each drainage catchment in the project site that is to be sized per the Presumptive Approach.
Anthony J. Favreau
The Favreau Group
Springfield, OR
Permit Number:
Catchment ID:
Project Address:
Designer:
Company:
Flow Control (FC)No
Destination (DT)No *An infiltration facility must be chosen as the facility type to meet destination requirements
Site Data-Post Development
Total Square Footage Impervious Area=10407 sqft Total Square Footage Pervious Area=10883 sqft
Impervious Area CN=98 Pervious Area CN=85
Total Square Footage of Drainage Area=21290 sft Time of Concentration Post Development=5 min
Weighted Average CN=91
Site Data-Pre Development (Data in this section is only used if Flow Control is required)
Pre-Development CN=85 Time of Concentration Pre-Development=10 min
Soil Data
Tested Soil Infiltration Rate=5 in/hr (See Note 4)N/A in/hr
Design Soil Infiltration Rate=2.5 in/hr
Design Storms Used For Calculations
Design Storm
1.4 inches Water Quality
3.6 inches Flood Control
3.6 inches Flood Control
Facility Data
Facility Type=Facility Surface Area=336 sqft
Surface Width=14 ft Facility Surface Perimeter=76 ft
Surface Length=24 ft Facility Bottom Area=336 sqft
Facility Side Slopes=0 to 1 Facility Bottom Perimeter=76 ft
18 in Basin Volume=504.0 cf
24 in Ratio of Facility Area to Impervious Area=0.016
Max. Ponding Depth
in Stormwater Facility=
Depth of Growing Medium (Soil)=
Destination Design=
Soil Infiltration Rate
Filtration Stormwater Planter
Destination
24-hour
Rainfall DepthRequirement
Pollution Reduction
Flow Control
3/21/2024-10:41 AM 1
Pollution Reduction-Calculation Results
Peak Flow Rate to Stormwater Facility =0.083 cfs Peak Facility Overflow Rate=0.000 cfs
1202 cf Total Overflow Volume=0 cf
Max. Depth of Stormwater in Facility=6.0 in
Drawdown Time=0.2 hours
Yes Facility Sizing Meets Pollution Reduction Standards?
YES Meets Requirement of No Facility Flooding?
YES Meets Requirement for Maximum of 18 Hour Drawdown Time?
Flow Control-Calculation Results
Peak Flow Rate to Stormwater Facility =0.373 cfs Peak Facility Overflow Rate=0.354 cfs
4725 cf Total Overflow Volume=2745 cf
Max. Depth of Stormwater in Facility=18.0 in 0.019 cfs
Drawdown Time=7.2 hours
Pre-Development Runoff Data
Peak Flow Rate =0.254 cfs
Total Runoff Volume =3732 cf
N\A Facility Sizing Meets Flow Control Standards?
Total Runoff Volume to Stormwater
Facility =
Total Runoff Volume to Stormwater
Facility =
Peak Off-Site Flow Rate
Filtration Facility Underdrain=
3/21/2024-10:41 AM 2
N\A Meets Requirement for Post Development offsite flow less or equal to Pre-Development Flow?
N\A 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
N/A cf Total Overflow Volume=N/A cf
Max. Depth of Stormwater in Facility=N/A in
Drawdown Time=N/A hours
N/A Facility Sizing Meets Destination Standards?
N/A Meets Requirement of No Facility Flooding?
N/A Meets Requirement for Maximum of 30 hour Drawdown Time?
Total Runoff Volume to Stormwater
Facility =
3/21/2024-10:41 AM 2