HomeMy WebLinkAboutApplication APPLICANT 4/21/2022B r JOHNSON
CBRODERICK
ENGINEERIN
Memorandum
To: Clayton McEachern Dae:
From: Mikael Shields, P.E. Project Name:
Subject Stormwater System Design 1BE Project Number
325 West 131h Avenue
Eugene, Oregon 97401
541-338-9488 (office)
w JBE.usxom
April 20, 2022
Dave's Hot Chicken
21016.02
This memo describes the design intent of the stormwater system for the referenced project
located at 1570 Mohawk Blvd., Springfield. The total site area is approximately 32,507 S.F of
which 22,330 S.F., or 61 % is impervious surface (buildings and pavement). The non -building
impervious area is 19,415 S.F. The remaining 10,177 S.F. of the site is composed of landscaped
areas including the stormwater treatment/infiltration areas. The site is currently developed with
a building and paved parking area that drains to the public piped stormwater system in Mohawk
Blvd. with no stormwater treatment provided. 57% of the non -building impervious area runoff
will be treated through vegetative means in Rain Garden "A" and Rain Garden W. The
remaining 8,354 S.F. of non -building impervious area runoff will receive mechanical treatment
through double chamber catchbasms that include replaceable oil filtration filters. Roof drains
from the proposed building will connect to the existing public storm drain system.
The rain garden treatment facilities are designed in accordance with the City of Eugene
Stormwater Design Manual (ESDM) and sized using the Stormwater Surface Filtration/Infiltration
Facirrty Sizing Spreadsheets which are attached for reference.
O1-101 November 5, 2020
Stormwater Surface Filtration/Infiltration Facility Sizing Spreadsheet
24 Hour Storm, NRCS Type 1A Rainfall Distribution
City of Eugene
Name:
Dave's Hot Chicken
Address:
1570 Mohawk Blvd.
1.4 intoes
Sorinafield. OR
:r:
MDS
ry:
Johnson Broderick Engineers
Data 5/28/2021
Permit Number: N/A
Catchment ID: Rain Garden "A"
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 correlate the appropriate
calculations with the facility.
The maximum drainage catchment to be modeled per the Presumptive Approach is 1 acre (43,56D SF)
For infiltration facilities in Class A or B soils where no infiltration testing has been perfromed use an infiltration rate of D.5 in/hr.
For all facilities use a maximum soil infiltration rate of 2.5 in/hr for topsoillgrowing medium,
"yes"from the drops own boxes below next to the design standards requirements for this facility.
Pollution Reduction (PR)Yes
Flow Control (FC)j No
Destination(DT) Yes 'An inflbaWn fxiltt,must be crM1am w8w boxy toe to mea deBmbon RQ:rernem
Total Square Footage Impervious Area= 4778 sgfl
Impervious Area CN=j 98
Total Square Footage of Drainage
weighed Averat
Data
Total Square Footage Pervious Area= 1765 sgfl
Pervious Area CN::85
Time of Concentration Post Development= min
Pre-0evelopmeM CN= 94 Time of Concentration Pre-0evelopmeM= 10 min
Tested Soil Infiltration Rate= in/hr(See Nme 4) Destination Design: in/hr
Design Soil Infiltration Rate= 2.5 in /hr Soil Infiltration Rate
Re uiremeM
Rainfall De [h
Desi n Storm
Pollution ReducBan
1.4 intoes
Wale Quality
Flow Control
3.8 inches
lFlood Control
Destination
I 3.8 inches
lFlood Control
Facility Ty{
Surface W d
Surface Lang
Facility Side Slop(
Max. Ponding Depth
in Stormweder Facility=
Depth of Growing Medium (So
EIY.'AY.'rYYA1F5�581
Facility Surface
Facility Surface Perri
Facility Bottom
Facility Bottom Perri
Ratio of Facility Area to
Pollution Reduction-Calculation Results
Peak Flow Rate to Stormwater Facility e 0 D3? cfs
Peak Facility Overflow Rate= D.DDD cfs
Total Runoff Volume to Stormwater
Facility= 480 of
Total Overflow Volume= Def
Max. Depth of Stormwater in Facility= 0.3 in
Drawdown Time= 0.2 hours
77-7-1Facility Sizing Meets Pollution Reduction Standards?
YES Meets Requirement of No Facility Flooding?
YES Meets Requirement for Maximum of 18 Hour Drawdown Time?
Flow CoMroltalculation Results
Peak Flow Rate to!tormwater Facilitya 0.129 efs
Peak Facility Overflow Role= D.DDD efs
Total Runoff Volume to Stormwater
Facility= 1823 of
Total Overflow Volume= Def
Peak ORSite Flow Rate
Max. Depth of Stormwater in Facility= 5.4 in
Filtration Facility Underdrairn NVI cfs
Drawdown Time= 0.2 hours
Pre-Develooment Runoff Data
Peak Flow Rate= D 114 cfs
Total Runoff Volume =1 1599 cf
NT Facility Sizing Meets Flow Control Standards?
NSA Meets Requirement for Post Development offsite flow less or equal to Pre-Development Flow,
L
Nj Meets Requirement for Maximum of 18 Hour Drawdown Time?
Destination{alculation Results
Peak Flow Rate to Stormwater Facility a 0.129 efs
Peak Facility Overflow Rate= 0088 cis
Total Runoff Volume to Stormwater
Facility= 1823 of
Total Overflow Volume= 265 cf
Max. Depth of Stormwater in Facility= 6.0 in
Drawdown Time= 3.2 hours
NO Facility Sizing Meets Destination Standards?
=Meets Requirement of No Facility Flooding?
=Meets Requirement for Maximum of 30 hour Drawdown Time?
EFXVX YYAA.SI5 "J
Stormwater Surface Filtration/Infiltration Facility Sizing Spreadsheet
24 Hour Storm, NRCS Type 1A Rainfall Distribution
City of Eugene
Name:
Dave's Hot Chicken
Address:
1570 Mohawk Blvd.
Yes
Sorinafield. OR
:r:
MDS
ry:
Johnson Broderick Engineers
Data 5/28/2021
Permit Number: N/A
Catchment ID: Rain Garden "B"
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 correlate the appropriate
calculations with the facility.
The maximum drainage catchment to be modeled per the Presumptive Approach is 1 acre (43,56D SF)
For infiltration facilities in Class A or B soils where no infiltration testing has been perfromed use an infiltration rate of D.5 in/hr.
For all facilities use a maximum soil infiltration rate of 2.5 in/hr for topsoillgrowing medium,
"Yes"from the dropdown boxes below next to the design standards requirements for this facility.
Pollution Reduction (PR)Yes
Rainfall De [h
Desi n Storm
Flow Control (FC)j
Yes
Wale Quality
Destination(DT)
Yes
•Aninab,mn nmp must be clxsm wdw boxy toe to mea deBmbon RQ:rernedc;
Total Square Footage Impervious Area= 6283 sgfl
Impervious Area CN=j g8
Total Square Footage of Drainage
weighed Averat
Data
Total Square Footage Pervious Area= 61%sgfl
Pervious Area CN::85
Time of Concatenation Post Developmem= min
Pre-0evelopmeM CN= 94 Time of Concentration Pre-0evelopmeM= 19 min
Tested Soil Infiltration Rate= in/hr(See Nme 4) Destination Design: in/hr
Design Soil Infiltration Rate= 2.5 in /hr Soil Infiltration Rate
Re uiremeM
Rainfall De [h
Desi n Storm
Pollution ReducBan
1.4 intoes
Wale Quality
Flow Control
3.8 inches
lFlood Control
Destination
I 3.8 inches
lFlood Control
Facility Ty{
Surface W d
Surface Leng
Facility Side Slop(
Max. Ponding Depth
in Stormweder Facility=
Depth of Growing Medium (So
EIY.'AY.'rYYA1FYJ5rl
Facility Surface
Facility Surface Parti
Facility Bottom
Facility Bottom Parti
Ratio of Facility Area to
Pollution Reduction-Calculation Results
Peak Flow Rate to Stormwater Facility eIcfs
Peak Facility Overflow Rate= D.DDD cfs
Total Runoff Volume to Stormwater
Facility=of
Total Overflow Volume= Def
Max. Depth of Stormwater in Facility=in
Drawdown Time=hours
777-71Facility Sizing Meets Pollution Reduction Standards?
YES Meets Requirement of No Facility Flooding?
YES Meets Requirementfor Maximum of 18 Hour Drawdown Time?
Flow Controltalculation Results
Peak Flow Rate to Stormwater Facilitya 0.220 efs
Peak Facility Overflow Role= D,DDD efs
Total Runoff Volume to Stormares
Facility a 2?88 cf
Total Overflow Volume= D of
Peak ORSite Flow Rate
Max. Depth of Stormwater in Facility= 3.9 in
Filtration Facility Underdrairn NV�cfs
Drawdown Time= 0.2 hours
Pre-Develooment Runoff Data
Peak Flow Rate= D,218 cfs
Total Runoff Volume =1 31)51) of
77-771Facility Sizing Meets Flow Control Standards?
YES Meets Requirement for Post Development offsite flow less or equal to Pre-Development Flow,
VES JMeets Requirement for Maximum of 18 Hour Drawdown Time?
Destination{alculation Results
Peak Flow Rate to Stormwater Facility e D,221) efe
Peak Facility Overflow Rate= 0039 cis
Total Runoff Volume to Storman's
Facility a 2788 of
Total Overflow Volume= 223 ci
Max. Depth of Stormwater in Facility= 6.0 in
Drawdown Time= 2.7 hours
NO Facility Sizing Meets Destination Standards?
=Meets Requirement of No Facility Flooding?
=Meets Requirement for Maximum of 30 hour Drawdown Time?
EIY.'AY.'rYYA%YJ:SI