HomeMy WebLinkAboutStudies APPLICANT 11/30/2020Stormwater Management Plan and
Drainage Study
Hayden Bridge Filtration Plant:
Lab Building Parking Lot
Branch Engineering Project #20-234
For
Nathan Endicott, P.E.
Eugene Water and Electric Board
4200 Roosevelt Blvd
Eugene, Oregon 97402
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Mower o..'.;_.
OREGON
Err. DEr&M 31, 2020
ENIGINEERING= November 19, 2020
Slue 1977
civil - transportation
structural - geotechnical
SURVEYING
www.BranchEngineering.com
Contents Page No
1.0 Introduction............................................................................................................... 1
2.0 Existing conditions.................................................................................................1
2.1 Topography & Existing Drainage 1
2.2 Soils 1
3.0 Proposed Development.........................................................................................2
4.0 Stormwater Management.....................................................................................2
4.1 Stormwater Summary 2
4.2 Stormwater Analysis 3
5.0 Stormwater Compliance........................................................................................3
5.1 Water Cual ty Treatment 3
5.2 Flow Control 4
6.0 Conclusion..................................................................................................................4
Appendices Description
Appendix A HydroCAD Analysis
Appendix B NRCS Soils Data
Appendix C Stormwater Scoping Sheet
Hayden Bridge Filtration Plant, (20-234)
November 19, 2020
1.0 INTRODUCTION
This Stormwater Management Plan (SWMP) has been prepared for the EWEB Hayden Bridge
Filtration Plant located northwest of the intersection of Hayden Bridge Road and Marcola Road,
atop of Mina Butte. The new development consists of a new lab and backup services building with
parking lot improvements. The tax lot of the project site is TM 17021900 TL 03300.
The project falls within the City of Springfield but no runoff from the site will reach existing city
systems. There is no public system in the vicinity of the site for it to drain into. All runoff will be
captured and filtered on-site. There is a conveyance system in the area. This system captures
current runoff and directs it downstream to a pond located on the northeast corner of the site.
This report will display the drainage conditions of the site and how they meet current city code
requirements for treatment.
2.0 EXISTING CONDITIONS
2.1 TOPOGRAPHY & EXISTING DRAINAGE
The existing site is sloping towards the east with elevations ranging between 588 and 580 feet.
The subject site is situated on approximately 50.28 acres, with the project area being
approximately 1.5 acres. The site is primarily used as a filtration plant with some landscaping
surrounding the site.
The current drainage pattern is that the runoff drains to the northeast through an existing
Swale and filters into a sludge pond which is a part of the filtration plant process. The current
Swale receives stormwater off a disinfection building and the surrounding land
The following table displays the area of existing development before any improvements are
made.
Table 1: Ecisting Basin Summary
Basin
ID
Summary
Area (S. F)
SUM
Existing
Grass/
Building
Existing
Impervious
Existing
Landscape
Roof
Area
Gravel
(CN -75)
(CN=98)
(CN=98)
(CN=90)
EC
Existing
Conditions
23,250
8,500
14,660
18,840
65,250
2.2 SOILS
According to the Natural Conservation Service Website mapping services, the existing soils at
the site are Rimer cobbly silty clay loam (NRCS Soil #113E). This and is in the Hydrologic Group
C, where water transmission through the and is somewhat restricted. Appendix B includes the
NRCS Web Sold Survey data.
Branch Engineering, Inc.
Hayden Bridge Filtration Plant, (20-234)
November 19, 2020
3.0 PROPOSED DEVELOPMENT
This report is for the stormwater treatment and management resulting from the proposed parking
lot design and improvements around the new Lab building which is currently under construction
at the EWEB Hayden Bridge Filtration Plant in Springfield.
The development consists of an under -construction lab and backup services building along with
the proposed parking lot improvements. The existing swale located to the east of the existing
buildings will receive more stormwater from the added impervious surface; i.e. the new parking
lot. The total added impervious area is approximately 19,900 sq ft
Stormwater treatment will be on-site and will not reach any City of Springfield stormwater
systems, therefore the stormwater from the new impervious areas does not add any impact to the
city systems. Stormwater capacity does not pose any concerns due to the unique circumstances of
the project site. All runoff can be captured and filtered on-site starting with the existing swale and
eventually depositing runoff into sludge ponds downstream of the swale. Stormwater that enters
the sludge pond will have an imperceptible impact on the pond due to the size of pond. From
there, the water will enter into the filtration plant process and be treated accordingly.
4.0 STORMWATER MANAGEMENT
4.1 STORMWATER SUMMARY
A majority of the impervious surfaces will be directed to the swale which will have filtration
capabilities with the vegetation that will provide the basic level of water quality treatment.
The first goal for the stormwater design was to use the resources on-site in order to eliminate
impacts to the public storm systems. The pre-existing vegetated Swale will serve as a basin to
direct and treat stormwater runoff from the existing as well as the new impervious areas. As all
the stormwater will be treated on site by the swale and then the water treatment facility, the SDC's
and monthly stormwater fees from the new improvements will be very minimal.
The majority of the runoff from the existing structures; i.e. planters, sidewalks, building roofs and
asphalt roadways and pavements was already being directed to the existing Swale. This conveyance
system will not be interrupted from the proposed parking lot improvements. A dual chamber catch
basin is added near the northwestern corner of the under -construction lab building. Majority of
the new impervious area from the parking lot will be directed to the dual chamber catching basin,
which will then be connecting into an existing stormwater pipe leading it to the existing swale. The
remainder of the new impervious area will be entering the swale through a curb cutout down the
drive aisle.
According to the City of Eugene Stormwater Management Manual, Swales "are long and narrow
vegetated and grassed depressions used to collect, detain and convey stormwater runoff which
allows pollutants to settle and filter out as the water flows through the facility. " The swale will treat
a majority of the runoff from the new pavement as well as the roofs.
Branch Engineering, Inc.
Hayden Bridge Filtration Plant, (20-234)
November 19, 2020
4.2 STORMWATER ANALYSIS
Stormwater calculations were determined HydroCAD 10.00 modelling software. HydroCAD 10.00
utilizes the Santa Barbara Unit Hydrograph hydraulic modeling method. All results of the analysis
are included in Appendix A. 24 -Hour Rainfall depths are based on City of Springfield Engineering
Design Standards & Procedures Manual, Chapter 4.
The site was split into 4 basins:
• Basin 1 - Is the existing building roof area that is directed to the swale located to the east
of the under -construction and existing building.
• Basin 2 - Consists of the existing landscape areas. The stormwater runoff from this basin
is directed to the existing swale as well.
• Basin 3 - Is the second largest basin It covers most of the existing impervious areas from
the pavement, sidewalk and existing asphalt roadway. The stormwater runoff from this
basin is directed to the existing swale.
• Basin 4 - Was previously a gravel pad, but now will be converted to asphalt pavement. This
basin area was previously classified as an impervious area, even though gravel has a lower
CN of 90 compared to a higher CN of 98 for asphalt surface. It can be argued that the
stormwater runoff from this basin cannot be completely classified as new impervious area.
The stormwater runoff from this area will be directed to the existing swale.
The following table displays the areas of existing and new development after improvements
have been made. New impervious areas have been added to the site by replacing existing gravel
areas. Hence, there is very slight increase in the total area being directed to the swale.
Table 2 PostDevelopmentBasin Summary
5.0 STORMWATER COMPLIANCE
5.1 WATER QUALITY TREATMENT
The form of water quality treatment for the stormwater runoff of the impervious surfaces is
described by two different processes. The first process of treatment will occur as the runoff filters
through the vegetated swale which is located alongside the existing driveway of the site and runs
downhill towards a sludge pond. The swale will discharge the runoff through a catch basin that
will deposit it into the sludge pond. The second process of treatment occurs after the runoff enters
Branch Engineering, Inc.
Swale
Basin
Building Roof
Landscape/Grass
Impervious Area
Minimum
ID
Summary
(CN=98)
(CN =79)
(pavement)
sl1M
Travel Time
(CN=98)
(min)
Existing Areas
EB
—Developed
8,500
23,250
13,750
Condition
65,400
12.2
NI
New
_
19'900
Improvements
5.0 STORMWATER COMPLIANCE
5.1 WATER QUALITY TREATMENT
The form of water quality treatment for the stormwater runoff of the impervious surfaces is
described by two different processes. The first process of treatment will occur as the runoff filters
through the vegetated swale which is located alongside the existing driveway of the site and runs
downhill towards a sludge pond. The swale will discharge the runoff through a catch basin that
will deposit it into the sludge pond. The second process of treatment occurs after the runoff enters
Branch Engineering, Inc.
Hayden Bridge Filtration Plant, (20-234)
November 19, 2020
the existing sludge pond, and runs through the filtration plant process beginning at the sludge
pond
The swale described above was designed to meet City of Eugene Stormwater Management
requirements. This section will briefly confirm that the treatment mechanisms are in fact meeting
those requirements.
From the HydroCAD analysis in Appendix A, the minimum travel time is above 9 minutes for the
swale. This shows that the existing swale layout and length provide adequate treatment for the
new impervious areas and the existing landscape and impervious areas.
5.2 FLOW CONTROL
Due to the site's unique self-sufficient conveyance and water treatment system, this site is not
required to detain runoff in order to meet pre -developed discharge rates meeting the City's flow
control requirements. Off-site flow control is not a concern due to no off-site runoff.
The depth of the swale varies, but it is generally over 0.6 feet. During a 25 -year storm event, from
the HydroCAD calculation in Appendix A, the average depth at peak storage is 0.28 feet. Therefore,
it is safe to conclude that the capacity of the system will be sufficient during a 25 -year storm event
and the swale will not be experiencing any overflow effects.
6.0 CONCLUSION
The stormwater system for the Hayden Bridge Filtration Plan Project has been designed to be self-
sufficient. While the swale provides standard filtration treatment of the runoff from new and
existing surfaces, the unique situation of the site being a water filtration plant provides additional
treatment and eliminates water from leaving the site. Therefore, this project meets and exceeds
City of Springfield requirement for stormwater treatment and flow control.
Branch Engineering, Inc.
4
APPENDIX A
Hyd roCAD Analysis
EC
Existing Areas - Existing
Conditions
EB
6R
Existing Areas -
Developed Condition Existing Swale
NI
New Improvements
Subcat Reach On Link Routing Diagram for 20-234 StonnModel WD—SWALE
Prepared by Branch Engineering, INC, Printed 11/18/2020
Hydro AD®10,00-25 sM 098]8 O 2019 Hydro AD So%ere SduIkns LLC
Branch Enaineerina. INC
Type lA 24 -hr 2 yr Rainfall=3.30"
Printed 11/182020
Paae 2
Summary for Subcatchment EB: Existing Areas -Developed Condition
Runoff = 0.55 cfs @ 8.01 hrs, Volume= 0.182 af, Depth= 2.09"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs
Type IA 24 -hr 2 yr Rainfall=3.30"
23,250
79
50-75% Grass cover, Fair, HSG C
* 8,500
98
Existing Building
* 1,500
98
Sidewalk + CONC Areas
* 5,680
98
Existing Asphalt Road
* 6,570
98
Existing Asphalt Pavement
45,500
88
Weighted Average
23,250
51.10% Pervious Area
22,250
48.90% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry,
Summary for Subcatchment EC: Existing Areas - Existing Conditions
Runoff = 0.83 cfs @ 7.99 hrs, Volume= 0.271 af, Depth= 2.17"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs
Type IA 24 -hr 2 yr Rainfall=3.30"
23,250
79
50-75% Grass cover, Fair, HSG C
* 8,500
98
Existing Building
* 14,660
98
Existing Impervious
* 18,840
90
Existing Gravel
65,250
89
Weighted Average
42,090
64.5196 Pervious Area
23,160
35.49% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry,
Summary for Subcatchment NI: New Improvements
Runoff = 0.35 cfs @ 7.94 hrs, Volume= 0.117 af, Depth= 3.07'
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs
Type IA 24 -hr 2 yr Rainfall=3.30"
rmModel_Wf_SWALE Type lA 24 -hr 2 yr Rainfall=3.30"
Branch Enaineerina. INC Printed 11/182020
Area (sf) CN Description
* 19,900 98 New Asphalt
19,900 100.00% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry,
Summary for Reach 611: Existing Swale
Inflow Area = 1.501 ac, 64.45% Impervious, Inflow Depth = 2.39" for 2 yr event
Inflow = 0.90 cfs 7.99 hrs, Volume= 0.298 of
Outflow = 0.89 cfs 8.03 hrs, Volume= 0.298 af, Atten= 1%, Lag= 2.7 min
Routing by Dyn-Scor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs / 2
Max. Velocity= 0.39 fps, Min. Travel Time= 5.2 min
Avg. Velocity = 0.17 fps, Avg. Travel Time= 11.7 min
Peak Storage= 277 cf @ 8.03 hrs
Average Depth at Peak Storage= 0.22'
Bank -Full Depth= 1.00' Flow Area= 17.0 sf, Capacity= 15.58 cfs
9.00' x 1.00' deep channel, n= 0.250
Side Slope Z -value= 8.0'f Top Width= 25.00'
Length=120.0' Slope= 0.0400 'f
Inlet Invert= 582.50', Outlet Invert= 577.70'
Branch Enaineerina. INC
Type IA 24 -hr 25 yr Rainfall=4.80"
Printed 11/182020
C Paae 4
Summary for Subcatchment EB: Existing Areas -Developed Condition
Runoff = 0.94 cfs @ 7.99 hrs, Volume= 0.303 af, Depth= 3.48"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs
Type IA 24 -hr 25 yr Rainfall=4.80"
23,250
79
50-75% Grass cover, Fair, HSG C
* 8,500
98
Existing Building
* 1,500
98
Sidewalk + CONC Areas
* 5,680
98
Existing Asphalt Road
* 6,570
98
Existing Asphalt Pavement
45,500
88
Weighted Average
23,250
51.10% Pervious Area
22,250
48.90% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry,
Summary for Subcatchment EC: Existing Areas - Existing Conditions
Runoff = 1.39 cfs @ 7.97 hrs, Volume= 0.447 af, Depth= 3.58"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs
Type IA 24 -hr 25 yr Rainfall=4.80"
23,250
79
50-75% Grass cover, Fair, HSG C
* 8,500
98
Existing Building
* 14,660
98
Existing Impervious
* 18,840
90
Existing Gravel
65,250
89
Weighted Average
42,090
64.5196 Pervious Area
23,160
35.49% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry,
Summary for Subcatchment NI: New Improvements
Runoff = 0.52 cfs @ 7.94 hrs, Volume= 0.174 af, Depth= 4.56"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs
Type IA 24 -hr 25 yr Rainfall=4.80"
rmModel_Wf_SWALE Type IA 24 -hr 25 yr Rainfall=4.80"
Branch Enaineerina. INC Printed 11/182020
Area (sf) CN Description
* 19,900 98 New Asphalt
19,900 100.00% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry,
Summary for Reach 611: Existing Swale
Inflow Area =
1.501 ac,
64.45% Impervious, Inflow Depth = 3.81" for 25 yr event
Inflow =
1.46 cfs
7.97 hrs,
Volume= 0.477 of
Outflow =
1.45 cfs
8.02 hrs,
Volume= 0.477 af, Atten= 1%, Lag= 3.0 min
Routing by Dyn-Scor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs / 2
Max. Velocity= 0.45 fps, Min. Travel Time= 4.4 min
Avg. Velocity = 0.20 fps, Avg. Travel Time= 10.0 min
Peak Storage= 383 cf @ 8.02 hrs
Average Depth at Peak Storage= 0.28'
Bank -Full Depth= 1.00' Flow Area= 17.0 sf, Capacity= 15.58 cfs
9.00' x 1.00' deep channel, n= 0.250
Side Slope Z -value= 8.0'f Top Width= 25.00'
Length=120.0' Slope= 0.0400 'f
Inlet Invert= 582.50', Outlet Invert= 577.70'
Branch Enaineerina. INC
Type IA 24 -hr I44Q Rainfall=0.83"
Printed 11/182020
Paae 6
Summary for Subcatchment EB: Existing Areas -Developed Condition
Runoff = 0.02 cfs @ 8.08 hrs, Volume= 0.014 af, Depth= 0.16"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs
Type IA 24 -hr WQ Rainfall=0.83"
23,250
79
50-75% Grass cover, Fair, HSG C
* 8,500
98
Existing Building
* 1,500
98
Sidewalk + CONC Areas
* 5,680
98
Existing Asphalt Road
* 6,570
98
Existing Asphalt Pavement
45,500
88
Weighted Average
23,250
51.10% Pervious Area
22,250
48.90% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry,
Summary for Subcatchment EC: Existing Areas - Existing Conditions
Runoff = 0.04 cfs @ 8.07 hrs, Volume= 0.023 af, Depth= 0.19"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs
Type IA 24 -hr WQ Rainfall=0.83"
23,250
79
50-75% Grass cover, Fair, HSG C
* 8,500
98
Existing Building
* 14,660
98
Existing Impervious
* 18,840
90
Existing Gravel
65,250
89
Weighted Average
42,090
64.5196 Pervious Area
23,160
35.49% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry,
Summary for Subcatchment NI: New Improvements
Runoff = 0.07 cfs @ 7.97 hrs, Volume= 0.024 af, Depth= 0.63"
Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs
Type IA 24 -hr WQ Rainfall=0.83"
rmModel_Wf_SWALE Type IA 24 -hr 144Q Rainfall=0.83"
Branch Enaineerina. INC Printed 11/182020
Area (sf) CN Description
* 19,900 98 New Asphalt
19,900 100.00% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
10.0 Direct Entry,
Summary for Reach 611: Existing Swale
Inflow Area = 1.501 ac, 64.45% Impervious, Inflow Depth = 0.30" for WO event
Inflow = 0.09 cfs 8.03 hrs, Volume= 0.038 of
Outflow = 0.08 cfs 8.11 hrs, Volume= 0.038 af, Atten= 8%, Lag= 4.5 min
Routing by Dyn-Scor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs / 2
Max. Velocity= 0.16 fps, Min. Travel Time= 12.2 min
Avg. Velocity = 0.09 fps, Avg. Travel Time= 22.9 min
Peak Storage= 60 cf @ 8.11 hrs
Average Depth at Peak Storage= 0.05'
Bank -Full Depth= 1.00' Flow Area= 17.0 sf, Capacity= 15.58 cfs
9.00' x 1.00' deep channel, n= 0.250
Side Slope Z -value= 8.0'f Top Width= 25.00'
Length=120.0' Slope= 0.0400 'f
Inlet Invert= 582.50', Outlet Invert= 577.70'
APPENDIX B
NRCS Soils Data
e \ 11
MaYtle� B
r
�I
r G
- moues is �� -- •w
VC
7".
Soil Map—Lane County Area, Oregon
_SD, Natural Resources web Sol Survey WW2D2D
alaill Conservation Service National Cooperative Sail Survey Page 2 of 3
MAP LEGEND
MAP INFORMATION
Area at Wake. tA09
Spoil Area
The sal surveys that comprise your AOI were mapped at
Areaalnteresr(AQII
Q
army Spa
1:20,090.
Soils
Very Sony SpaWaming:
Soil Map may not be valud al Mrs scale.
0
Soil Map Unit Polygons
9
VJrf S p a
Enlargement of maps bethe scale of mapping can cause
,.,.
Soil Map Unic Lines
md Sell of the etail of mapping and accuracy of soil
4
Other
line placement. The maps do not show the small areas of
Map Unit Points
contrasting soils that could have been shown at a more detailed
Special Line FeaturesSoil
Special
Point Features
scale.
Lg
Blowout
water Features
Streams and Canals
Please rely on the bar scale on each map sheet for map
®
Borrow Pit
measurements.
Trenspartatian
Clay Spot
Rails
Source of Map: Natural Resources Conservation Service
0
Closed Depresdan
Web Soil SurveyURL:
Interstate Highways
Coordinate System: web Mercator(EPSG:3B5])
Gravel Pit
US Routes
Maps from the Web Soil Survey are based on the Web Mercator
Gravely Spa
Major Roads
projection, which preserves and shape but
schdistorts
and area, projection that preserves area, such as the
ion that
®
Landfill
Local Roads
Abersdistance
o
Albers equal-area conic projection, should be used if more
Lava Flow
accurate calculations of distance or area are req uired,
Background
aga
Marsh or swamp
.
Aerial Photography
This productis generated from the USDAgRCS tended data as
of Ne version date(s) listed below.
.�.
Mine or Query
Soil Survey Area: Lane County Area,
®
Miscellaneous Ydscer
un11,20M
Survey Area Data: Version 1l, Jun 11, 2020
®
Perennial VMmer
Sail map units are labeled (as space allows) for map scales
y,
Rock Outcrop
1:50,099 or larger.
A
Saline Spot
Dates) aerial images were photographed: Jun 12, 2019i
19, 2019
Sandy Spot
The odhophoto or other base map on which the soil lines were
Severely Eroded Spot
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
Sinkhole
shifting ofmap unit boundaries may be evident,
�p
Slide or Slip
Sodic Spot
_SD, Natural Resources web Sol Survey WW2D2D
alaill Conservation Service National Cooperative Sail Survey Page 2 of 3
Sal Map�ane Connty Area, Oregon
Map Unit Legend
LSDA Natural Resources Web Soil Survey &14/2020
iMi Conservation Serme National Cooperatirve Soil Survey Page 3 of3
Map Unit Synibd
Map Unit Name
Acres in AOI
Percent of AOI
32
Coburg4 ffian land cornplex
1.2
2.2%
WC
Nekle silly day loam, 21012
percent slopes
0.1
0.2%
108C
Philornath cobbly slay day, 310
12 percent slopes
0.1
0.1%
113C
Rihier cobbly silty clay loam, 2
to 12 percent slopes
22.7
43.4%
113E
Ribier cobbly silty clay loam,
1210 30 percent slopes
2].8
53.2%
119
Salern-Urban land complex
0.4
0.8%
Toads far Area of Interest
52.2
100.0%
LSDA Natural Resources Web Soil Survey &14/2020
iMi Conservation Serme National Cooperatirve Soil Survey Page 3 of3
Map Unit Description: Ritner cobbly silty clay loam, 12 to 3D percent slopes --lane County
Area, Oregon
Lane County Area, Oregon
113E—Ritner cobbly silty clay loam, 12 to 30 percent slopes
Map Unit Setting
National map unit symbol. 233t
Elevation. 400 to 1,800 feet
Mean annual precipitation: 40 to 60 inches
Mean annual air temperature: 50 to 54 degrees F
Frost -free period. 165 to 210 days
Farmland classification. Not prime farmland
Map Unit Composition
Rkner and similar soils. 85 percent
Estimates are based on observations, descriptions, and transects of
the mapunit.
Description of Rimer
Setting
Landform: Hills
Landform position (two-dimensional): Shoulder, summit
Landform position (three-dimensional): Interfluve, nose slope
Down-slope shape: Linear
Across -slope shape: Linear
Parent material. Cobbly colluvium derived from basic igneous rock
Typical profile
Oi-Oto 1 inches. slightly decomposed plant material
Hl - 1 to 8 inches: cobbly silty clay loam
1-12 - 8 to 33 inches: very cobbly silty clay loam
H3 - 33 to 37 inches: unweathered bedrock
Properties and qualities
Slope: 12 to 30 percent
Depth to restrictive feature: 20 to 40 inches to lithic bedrock
Drainage class. Well drained
Capacity of the most limkirg layer to transmit water
(Ksat): Moderately high (0.20 to 0.57 in/hr)
Depth to water table: More than 80 inches
Frequency of floodirg: None
Frequency of ponding: None
Available water capacity. Low (about 4.9 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Lard capability classification (nonirrigated): 6s
Hydrologic Soil Group: C
Forage suitability group: Well Drained > 15% Slopes
(GO02XY0010R)
Other vegetative classification. Well Drained > 15% Slopes
(GO02XY0010R)
LSDA Natural Resources l4pb Soil Survey w14/202o
i Conservation Serves National Cooperative Soil Survey Pagel oft
Map Unit Description: Ritner cobbly silty clay loam, 12 to 30 percent slopes --lane County
Area, Oregon
Hydric soil rating: No
Data Source Information
Soil Survey Area: Lane County Area, Oregon
Survey Area Data: Version 17, Jun 11, 2020
LSDA Natural Resources Web Soil Survey g/14/202o
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APPENDIX C
Stormwater Scoping Sheet
225 FIFTH STREET
SPRINGFIELD, OR 97477
PHONE: 541.726.3753
FAX. 541,726,1021
www springfield-or.gov
STORMWATER MANAGEMENT SYSTEM SCOPE OF WORK
--------------------- (Area below this line filled out by Applicant) -------------------
(Please return to Clayton McEachern @ City ofSpringrehiDevelopmentand Public Works; Fax # 736-1021, Phone # 736-1036),
email: cmceachern@springreld-or.gov
Project Name: 0A -(opo gypr�;t,gg g,t,�,,,g Applicant: "Bg}� &jBtNESRIN6 WC
Assessors Parcel #: 1�-021�D6o3;oa A`twt-er Date: 6/Z& /2420
Land Use(s): w"m Ta.EAT+�+e4T Flour( Phone #: SI(/ - ?A - 063}
Project Size (Acres): ti 0.5-1.0 Fax #:
Approx. Impervious Area: IQ, too Fr2 Email: GREG nn 13AANCk6NBIN�12tniG. COM
Project Descrip ion (Include a copy of Assessor's map):
_PH'r-C(Q FAA-,Otr LOT ,N ;:eRo mT of L,+9 RUlr'Dl MCw C VrSaE4 CoNSTALC ts" 1.
JJ
Drainage Proposal (Public connection(s), discharge location(s), etc. Attach additional sheet(s) if necessary:
PLSC,AAR66 )0Tb Ca a.RZOT Sw A+e PrtaNy DA.NEWAy
(ove2SiTors, sUQllry VsT,6r&FM7 017µ RwHR Roca AS LINFa)
Proposed Stormwater Best Management Practices:
VE61"IT" INFI6TPATIbN TRepT#u WT 1N piSTtN6 Sw hCE,
he/ow this line filled out by the City and Returned m the Annlicamt) —
(At a minimum, all bases checked by the City on the frontand back of this sheet shall be submitted
for ana lication to be completefor submittal, although other requirements may benecessary)
Drainage Study Type (EDSPM Section 4.03.2): (Vote UH may be substituted for Rational Method)
❑ Small Site Study — (use Rational Method for calculations)
❑ Mid -Level Development Study— (use Unit HydmgraphMethod for calculations)
❑ Full Drainage Development Study — (use Unit Hydrograph Method for calculations)
Environmental Considerations:
❑ Wellhead Zone: n/a ❑ Hillside Development: Fla
❑ Wetland/Riparian: Fla ❑ Floodway/Floodplain: Fla
❑ Soil Type: 113c-Rittner Cobly silty clay loam ❑ Other Jurisdictions n/a
Downstream Analysis:
❑ N/A
❑ Flow line for starting water surface elevation:
❑ Design HGL to use for starting water surface elevation:
❑ Manhole/Junction to take analysis to:
Return to Clayton McEachern @ City of Springfield, email: cmceachern@spnngfield-orgov, FAX: (541) 736-1021
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COMPLETE STUDY ITEMS Fw Od a Use ONy.
*Based upon the informanam provided on the front of this sheet, the following represents a minimum of whm is needed for an
application to be complete for submittal with respect to drainage; however, this list should not be used in lieu ofthe Springfield
Development Code (SDQ or the City's Engineering Design Manual Compliance with these requirements does not constitute site
approval; Additional site specific information may be required Now: Upon scoping sheet submittal, ensure completed form has been
signed in the space provided below.
Interim De' n StandaMs/Water Quality (EDSPM Cha r3
Req'd N/A
7 ❑ All non -building rooftop (NBR) impervious surfaces shall be pre-treated (e.g. multi-chambered calchbasin Wail filtration
media) for slormwater quality. Additionally, a minimum of 50% of the NBR impervious surface shall be treated by
vegetated methods.
0 ❑ Where required, vegetative stormwater design shall be consistent with design standards (EDSPM Section 3.02), set forth
in Chapter 2 of the Eugene Stormwaler Management Manual.
❑ For new NBR impervious area less than 15,000 square feet, a simplified design approach may be followed as specified
by the Eugene Stormwater Management Manual (Sec2.4.1).
If a stormwaler treatment swale is proposed, submit calculations/specifications for sizing, velocity, flow, side slopes,
bottom slope, and seed mix consistent with City of Springfield or Eugene's Stormwater Management Manual.
Water Quality calculations as required in Section 3.03.1 of the EDSPM.
❑ All building rooftop mounted equipment, or other fluid containing equipment located outside of the building, shall
Zj
❑
0
0
❑ Drainage study prepared by a Professional Civil Engineer licensed in the state of Oregon.
Q' A complete drainage study, as required in EDSPM Section 4.03.1, including a hydrological study map.
Calculations showing system capacity for a 2 -year storm event and overflow effects of a 25 -year storm event.
The time of concentration (Tc) shall be determined using a 10 minute start throe for developed basins.
Review of DownstreamS stem EDSPM Section 4.03.4.0
QA
downstream drainage analysis as described in EDSPM Section 4.03A.C. On-site drainage shall be governed by the
Oregon Plumbing Specially Code (OPSC).
ElD
Elevations of the HGL and flow lines for both city and private systems where applicable.
❑
[D
Design of Storm Systems (EDSPM Section 4.04).
Q
Flow lines, slopes, rim elevations, pipe type and sizes clearly indicated on the plan set.
Minimum pipe cover shall be 18 inches for reinforced pipe and 36 inches for plain concrete and plastic pipe materials, or
proper engineering calculations shall be provided when less. The cover shall be sufficient to support an 80,00016 load
without failure of the pipe structure.
Manning's "n" values for pipes shall be consistent with Table 4-1 of the EDSP. All storm pipes shall be designed to
Existing and proposed contours, located at one fool interval. Include spot elevations and site grades showing how site
drains.
F� Private slormwater easements shall be clearly depicted on plans when private slormwaler flows from one property to
another.
Drywells shall not receive mnoff from any surface w/o being treated by one or more BMPs, with the exception of
residential building roofs (EDSP Section 3.03.4.A). Additional provisions apply to this as required by the DEQ. Refer to
the website: httn://www.deg.state.or.us/wg/uic/uie.htm for more information.
❑ Detention ponds shall be designed to limit runoff to pre -development rales for the 2 through 25 -year storm events.
*This form shall be Includedas an attachment, inside the front cover, of the stormwater study.
• IMPORTANT: ENGINEER PLEASE READ BELOW AND SIGNf
As the engineer of record, I hereby certify the above required items are complete and included with the submitted slormwaler study
and plan set. Signature Date
Form Version 5: Jane 2015
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