HomeMy WebLinkAboutApplication APPLICANT 11/10/2022October 20, 2022
City Administrator
City of Springfield
225 Fifth Street
Springfield OR 97477
Y
SSW
ENGINEERS.
CML 5111110AL HILAIX616111
ams LN96a PLIMI 16
2350 Oakmont Way, Suite 105
Eugene, OR 97401
Subject: ADU Narrative at 1021 71M1 Steet, Springfield OR 97477 (541),185-8383 Fax (541) 485-8384
wnwemengineem.wm
The following narrative is for the above property and will show compliance with the Springfield
Development Code (SDC) section 3.2.275 for Accessory Dwelling Units (ADU). The proposed ADU will
provide flexibility to accommodate changes in the current household sin and/or composition over the
course of time, allowing for intergenerational living. Construction of the ADU will be detached from the
primary single unit dwelling on the lot. The lot is zoned R, which allows the ADU.
Per SDC 3.2.275(F) the ADU meets the following criteria:
(1) The ADU is setback from the property line a minimum of 5 feet. ADU height is less than 14
foot in height and lot coverage is approximately 39% with the addition of the ADU. The ADU is
built to current codes.
(2) Per submitted plans ADU will contain a kitchen, bathroom and sleeping area that are completely
independent of the primary dwelling.
(3) ADU is 392 square feet which is less than permitted 800 square feet.
(4) Per submitted plans ADU has an entrance that is separate from the entrance of the primary
dwelling.
(5) A 3 foot hard surface walk way to 71 Street shall be provided.
(6) A new address will be given from the city at time of permit approval.
(7) Outdoor storage and garbage areas are screened from view from adjacent properties and those
across the street by the existing fence in the sides and back of the property and by the primary
dwelling in the front. The fence is approximately 6 foot tall.
(8) Structure is not a manufactured home or towable.
Per SDC 3.2.275(G) the ADU meets the following criteria for Match the Primary Dwelling Standards:
(1)(a) Exterior finish materials visually match those of the primary dwelling, consisting of
horizontal wood siding.
(1)(b) The ADU roof pitch matches the predominate roof pitch of the primary dwelling and the
other structures on site (see attached photos)
(1)(c) Trim around doors and windows match those of the primary dwelling.
(1)(d) Windows match those of the primary dwelling in proportion and orientation.
(the) Eaves project from the ADU the same distance as the eaves on the primary dwelling.
The ADU meets the criteria set forth in SDC 3.2.275(F) & (G). Please let us know if you have any
questions.
Sincerely,
Michael A Cox, P.E.
SSW Engineers Inc.
A --
Primary Dwelling Ai
Total
Predominant Roof
60% of Are.
Minor Roof
40% of Are
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S1M fORM: 20,14 (SiiTplif eO Approach }or Stnrrrfwater Management]
Application Sp,,.,-���t� Building Permit#\\-h-Ooc1'kL�'YPI
Address
a4E. P,v..\ G2 9�4Z-1 Residential/Commercial
Tax Lot # Icrcle onel
NRCS Soil Type or
Measured Infiltraiton Rate
Facility Sizing for Water Quality Flow Control and Flood Control*** Only for use in Tvoe A& B Soils
Surface Facilities
Farility5izing
Sizing Factor
Total Proposed New or Replaced Impervious Surface Area
�Bex 1
Impervious Area Reduction
0.13
=
Permeable Pavements sf
sf x
0.11
E. -Root sf
Sand Filter
sf x
Contained Planter sf
=
Sum of Total
Tree Credit sf
Impervious Area Managed
sT�
Total Impervious Area ReductionRO
Roz 2
Total Impervious Area Requiring Stormwater Managemment
--
� 8-0-X3
pci- MX z)
Facility Sizing for Water Quality Only
Overflow tog utter (weephole)�
Surface Facilities Impervious Area Managed
Sizing Factor
Faclity Surface Area
Rain Garden sf z
0.05 =
Stormwater Planter sf x
0.03 =
Swale sf x
0.06 =
Vegetated Filter Strip sf x
0.2 =
Sand Filter sf x
0.03 =
Facility Sizing for Water Quality and Flow Control
Surface Facilities Impervious Area Managed
Sizing Factor
Faclity Surface Area
Rain Garden sf x
0.11 =
Stormwater Planter 50-> sf x
0.07
•PCOJ14�'.4.r�
Sand Filter sf x
0.07 =
Facility Sizing for Water Quality Flow Control and Flood Control*** Only for use in Tvoe A& B Soils
Surface Facilities
Impervious Area Managed
Sizing Factor
Faclity Surface Area
Rain Garden
sf x
0.13
=
Stormwater Planter
sf x
0.11
=
Sand Filter
sf x
0.11
=
Sum of Total
Impervious Area Managed
sT�
Box4
Paint of Discharge (check ane(
(Box 4 must be equal or
greaterthan Sox 3)
Overflow tog utter (weephole)�
Overflow to Publicstorm drain pipe
Overflow to Open Drainage
Subsurface Infiltration
D
30 �,s
T�mT€e
Rall
Stora water Subsurface Filtrationllnfiltretion Facility Sizing Spreadsheet
24 Hour Storm, NRCS Type IA Rainfall Distribution
City of Eugene
1021 7th Street Parma Number: 811-224OD182WP1
Springfield. OR 97477 Catchment to: [Catchment to]
Michael A Cox, P.E.
SSW analnoers Inc.
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 acm (43,560 SF)
:or infiltration facilities in Class A or B soils whem no infiltration testing has been perfromed use an infiltration rate of 05 imhr.
rorman design
"Yes" from the dropdown boxes below next to the design standards requirements forthis facility.
Pollution Reduction(PR) Na 'sealage mmnrhes dreinng mmmenral Mn,hg la. regmm pre-mamemm man PMIMn mda on maulremems
Flow Control (FC)J Yes
Destination(DT) Yes •nn lml0anm muay mmm ce aw..n a. uwfoolrobpe W mea aesmnamnn regmremems
Total Square Footage Impervious Area=
503
sgft
Total Square Footage Pervious Area= 050
q
Impervious Area CN=
p
98
Flow Control
Pervious Area CN= 85
Total Square Footage of Drainage Area=
503
all
Time of Concentration Post Developnvmt Omin
Weighted Average CN=
98
Site Data -Pre Development (Data In this section's only
used if Flow Control Is required)
Pre -Development CN= 85
Time of Concentration Pre-Dewlopmanr mmn
Soil Data
Tested SoilingNraeon Ra[a+
iNhr ts.e ll.. 4) Destination Design- r/hr
Design Sotl Infiltration Fete=
imhr
Soil Infiltration Rate
Re uirement
Rainfall Depth
cesiumStorm
Pollution Reduction
t,41 c9_ s
Water Oualtt
Flow Control
3.6 inches
Flood Contrd
Destination
3.6 inches
Flootl Control
Surface
Facility Surf.
Facility Surface P
Basin
Effective
Facility Percent Storage Depth
Material DepN lin) Votes lint
Drains a Rock, Layer 1 12.0 35% 6.2
Drainage Rock, Lae;2
0.0
0.0
rotate= 120 in 4.2
Pollution eduction- alcu aflon Results
Peak Flow Rate to Stormwater Facility= 0.004 ds
Peak Facility Overflow Rate- 0.000 ds
Total Runoff Volume h Storacal;=�
Faclliry= 98 cf
Total Overflow Volume= 0 of
Max. Eff. Depth of Stormwater in FacIIItY 0.1 in
Drewdown Time= D.2 hours
r—N\7,7lFacility Sizing Meets Pollution Reduction Standards?
MA Jkleets Requirementof NO Facility Flooding?
NVQ MeetsRequirementfor Maximum of 18 Hour Drawdown Time?
Flow Control-Calculation Results
Peak Flow Rate to Stormwater Facility = 0.011 cis
Peak Facility Overflow Rate=ds
loate
Total Runoff Volume h Smmv
Facility= 141 &
Total Cver low Volume= d
Peak Off3ile Flow Rate
Max. Eff. Depth of Stornnvater in Facility= 1.3 in
Filtration Facility Underdraim;PIds
Drewdown Time= 0.2 hours
P .. vetoomen l Runion a
Peak Flow Rate = 0 con &s
Total Runoff Volume = 88 d
F-771Facility Sizing Meets Flow Control Standards?
YES Meeh Requirement for Post Development offsite flow leas or equal to Pre�Developmem Flow?
VES Meeh Requirement for Maximum of la Hour Drawdown Time?
Destinatlon-Calculatlon Rescue,
Peak Flow Rate to Stormwster Facility 0.011 ds
Peak Facility Overflow Rate-0.000 ds
Total Runoff Volume to Stormwate
Faclliry= 141 Lf
Total Overflow Volume= 0 of
Max. Eff. Depth of Stormwater in Facilay= 3.6 in
Drewdown Time= 0.2 hours
=Facility Sizing Meets Destination Standards?
VES Meets Requirement of No FacilityFlooding?
VES Meets Requirement for Maximum of 30 hour Drewdown Time?
11MQ022-11:21 AM