HomeMy WebLinkAboutStudies APPLICANT 11/3/2021380 Q Street, Ste 200
Springfield, Oregon 97477
(541)302-9790
kylemonis@ao-eng r corn
A G O Engineering ULC
Stormwater ReportA R
INE
Thurston Estates
8/41YpE
Location: 7399 Thurston Road, Springfield, OR ddTT
prepared W. Kyle MortGREG
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Reviewed 6y: Scott MomKyle Morris, PE
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ic.
Data 10/12/2021
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Type of Yroiect: Residential Subdivision
Project Overview
The applicant is proposing to construct a 10 -lot single family residential subdivision south of Thurston
Road on an approximate 2acre parcel. The subdivision will consist of publicly owned infrastructure
including roadways, utilities and stormwater infrastructure. To accommodate stormwater runoff it is
proposed to construct a stormwater pond within a tract to receive and process runoff from the new
rights-of-way and driveways on each lot. The primary outlet for this pond will be infiltration however a
new stonnline is proposed to be constructed as an overflow to the west, down Thurston Road and
conned into an existing 15" stormline approximately 400 feet from the site access. To process runoff
from the new single family roofs soakage trenches are proposed on each lot.
Existing Conditions
The existing site currently has some structures but mostly consists of grass cover and some scattered
trees. The structures present are a single-family residence, a garage and some small sheds. The
existing home and shed present on the future lot 1 is proposed to remain, other structures currently on-
site are proposed to be removed. Web Soil Survey classifies on-site soils as Chapman -Urban Land
Complex with a Hydrologic Soil Group rating of B. Per LIDAR elevation data the site has a very slight
slope directed to the north towards Thurston Road. It is assumed existing runoff from the site sheet
flows to the north during large storm events.
Springfield requires post -construction peak flowrates be equal to or less than pre -construction peak
flowrates. To analyze the pre construction peak flowrate from the site the following data will be utilized:
Land Type/Description: Grassland with HSG rating of B
Curve Number. 79
Infiltration
Infiltration testing was performed by Branch Engineering on July 151 2021 and a geotechnical report
was prepared on July 16' 2021 which includes the details of the testing and the results. The rate
measured during the testing was 16.5 in/hour. To meet the 2014 Eugene Stormwater Management
Manual requirements a design infiltration rate of 6 inlhourfor native soils will be utilized which provides
a safety factor of 2.75 when compared with the measured rate. Since this test was performed during
the summer, another infiltration test should be performed during the wet weather months (January or
February) to verify the infiltration rate and check the groundwater depth. Branch Engineering's report is
included with the appendix of this report.
To be consistent with the requirements outlined in the 2014 Eugene Stommater Management Manual,
a design infiltration rate of 2.5 in/hourwill be utilized for infiltration through imported soil growing mediums
such as is proposed in the pond. Soakage trenches discharging directly into native soils can utilize the
6 in/hour design rate as discussed above.
Proposed Destination
The primary destination for stormwater runorf will be infiltration during more normal storm events. For
larger design storm events a stormwater pipe is proposed to be installed down Thurston Road and
connect into an existing 15" stormwater line about 400 feet west of the site access. This existing 15"
stormwater line discharges into an existing swale north of Thurston Road right-of-way. The City of
Springfield basin map shows the entire site is to drain to the north as proposed.
Soakage Trenches are proposed to be installed for the single-family home roofs and thus stormwater
runoff from there will be infiltrated.
Post Constrmtion
It is proposed to construct a publicly owned and maintained stormwater pond within a tract as shown on
the plan. This pond would collect stormwater runoff from the new impervious rights-of-way on the site
and the private driveways that slope from the house onto the streets. Each driveway was assumed to
contribute approximately 500 square feet of impervious area that will drain into the public pond. In the
table below physical characteristics of the proposed pond are summarized:
Table 1: Pond Physical Characteristics
Facility
Bottom
Depth
Side
Slopes
Top
Area
Area [SF]
[F7]
[H:V]
[SF]
Water Quality
Detention
128
3.5
3:1
1,510
Pond
• Page 2
The pond will also have a 12" thick growing medium and a 12" thick rock chamber for storage. The
growing medium is proposed under the entire facility and the rock chamber is proposed to cover an area
of 564 Sf which is equivalent to the third contour of the pond shown on the plans. The total storage area
the proposed pond provides is summarized in the table below:
Table 2 Total Pond Storage
Open
Growing
Rock
Total
Storage
Medium (10%
Chamber
Storage
(100%Voids)
Voids)
(35% Voids)
2,493
32
197 2,722
Hydraulic Calculations
HydroCAD software was utilized to perform all hydraulic calculations. Below are parameters utilized in
calculating the existing conditions peak flowrates leaving the site from the development area:
Runoff Method: Santa Barbara Urban Hydrograph (SBUH)
Area: 1.99 acres
Curve Number. 98 Unconnected roofs
98 Impervious ROW
Time of Concentration: 61.9 minutes (Details for this included with HydroCAD node report)
Storm Type: Type lA 24 -hr
Storm Events: Water Quality -0.83 inches
2 -Year Storm — 3.30 inches
25 -Year Storm — 4.80 inches
To show detention requirements are met, both pre -construction and post -construction peak flowrates
leaving the site were calculated. Those values are summarized in the table below:
Table 3: Peak Flowmfes Summary
Storm Existing Conditions Post Construction
Event Peak Flowrate [cfs] Peak Flowrate [cfs]
2 -Year 0.29 0.14
25 -Year 0.63 0.19
As shown above, detention requirements are met as most stormwater runoff is proposed to infiltrate.
Along With peak flowrates, hydraulic grade lines were analyzed to ensure no flooding occurs within the
subdivision. Below is a table summarizing the pond elevations and outflow structure elevations.
Table 4: Pond Elevations (al(numbers in units of Feet)
0 Page 3
Pond FL.
1.51n.
Orifice
2In Orifice
Pond Top
522.40
1 523.40
1 523.90
1 525.90
0 Page 3
Below is a table summarizing the calculated HGIs within the pond in comparison to the above pond
elevations:
Table 5. Calculated Pond HGLs
Wat
PT
2 -Year
25 -Year
P
ty
521.26
1 524.52
1 525.16
1 525.90
As shown in the above table, all stormwater is contained within the pond during the 25 -year storm, and
thus won't cause any Flooding to habitable structures.
Pollution Control
As discussed, infiltration is proposed as the primary outflow during normal storm events. For single-
family roofs it is proposed to construct soakage trenches thus providing complete infiltration. For the
impervious roadways and driveways stormwater runoff will be routed through the proposed water quality
detention pond. This pond will be vegetated to meet City of Springfield requirements. As shown in the
tables above all stormwater is infiltrated during the Water Quality storm event as the peak HGL is below
the lowest orifice.
Conclusion
The proposed stormwater system will meet City of Springfield requirements. Detention requirements
will be met and pollution control also will be provided with the proposed infiltration and vegetation within
the pond. The proposed system as modeled will not pose any public safety or health risks.
Appendix
• HydroCAD Report
• Branch Engineering Site Infiltration Test Results
• Stormwater Scoping Sheet
9 Page 4
12R
O
Discharge Pond Tract Impervious ROW
6S
Existing Conditions
Subcat Reach on Link Routing Diagram for Thurston Storm Analysis 0630@OYi
Prepared by {enter your company name here}, Ported 10/12/2021
F7
CA s n 09993 ® 2020 HydmCAD Softam Solutions LLC
Thurston Storm Analysis 06-30-2021
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HydroCAD010.10-5a s/n 04993 02020 HydroCAD Software Solutions LLC Pane 2
Rainfall Events Listing (selected events)
Event# Event Storm Type Curve Mode Duration BIB Depth AMC
Name (hours) (inches)
I 01 -Wo Type IA 24 -hr Default 24.00 1 0.83 2
2 02-2 Year Type IA 24 -hr Default 24.00 1 3.30 2
3 03-25 Year Type IA 24 -hr Default 24.00 1 4.80 2
Thurston Storm Analysis 06-30-2021
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Area Listing (selected nodes)
Area
CN
Description
(acres)
(subcatch ment-nu mbers)
0.103
98
Driveways (125)
0.549
98
Impervious ROW (12S)
1.990
79
Pasture/grassland/range, Poor, HSG B (6S)
2.642
84
TOTAL AREA
Thurston Storm Analysis 06-30-2021
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Soil Listing (selected nodes)
Area
Soil
Subcatchment
(acres)
Group
Numbers
0.000
HSG A
1.990
HSG B
6S
0.000
HSG C
0.000
HSG D
0.652
Other
12S
2.642
TOTAL AREA
Thurston Storm Analysis 06-30-2021
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Ground Covers (selected nodes)
HSG -A
HSG -B
HSG -C
HSG -D
Other
Total
Ground
Subcatchment
(acres)
(acres)
(acres)
(acres)
(acres)
(acres)
Cover
Numbers
0.000
0.000
0.000
0.000
0.103
0.103
Driveways
12S
0.000
0.000
0.000
0.000
0.549
0.549
Impervious ROW
12S
0.000
1.990
0.000
0.000
0.000
1.990
Pasture/grassland/range, Poor
6S
0.000
1.990
0.000
0.000
0.662
2.642
TOTALAREA
Thurston Storm Analysis 06-30-2021
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Pipe Listing (selected nodes)
Line# Node
In -Invert
Out -Invert
Length
Slope n
Width
Diann/Height
Inside -Fill
Number
(feet)
(feet)
(feet)
(ft(ft)
(inches)
(inches)
(inches)
1 5P
521.48
520.94
180.0
0.0030 0.011
0.0
12.0
0.0
Thurston Storm Analysis 06-30-2021 Type M 24-hr 01-WQ Rainfall=0.83"
Prepared by {enter your company name here} Printed 10/12/2021
HydroCAD® 10.10-5a s/n 04993 ® 2020 HydroCAD Software Solutions LLC Pace 7
Time span=0.00-32.00 hrs, dt=0.05 hrs, 641 points
Runoff by SBUH method, Split Pervious/Imperv.
Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method
Subcatchment6S: Existing Conditions Runoff Area=1.990 ac 0.00% Impervious Runoff Depth>0.03"
Flow Length=500' Tc=61.9 min CN=79/0 Runoff-0.01 cls 0.005 of
Subcatchmentl2S: Impervious ROW Runoff Area=28,408sf 100.00% Impervious Runoff Depth=0.63"
Tc=10.0 min CN=0198 Runoff=0.10 cfs 0.034 of
Reach 12R: Discharge Inflow=0.00 cN 0.000 of
Outflow=0.00 cfs 0.000 of
Pond SP: Pond Tract Peak Elev=521.26' Storage=170 of Inflow=0.10 cfs 0.034 of
Discarded=0.03 cis 0.034 of Primary=0.00 cfs 0.000 of Outflow=0.03 cfs 0.034 of
Total Runoff Area = 2.642 ac Runoff Volume = 0.039 of Average Runoff Depth= 0.18"
75.32% Pervious= 1.990 ac 24.68% Impervious = 0.652 ac
Thurston Storm Analysis 06-30-2021 Type /A 24 -hr 01-WQ Rainfall=0.83"
Prepared by {enter your company name here} Printed 1011212021
HydroCAD®10.10-5a s/n 04993 02020 HydroCAD Software Solutions LLC Pace 8
Summary for Subcatchment 6S: Existing Conditions
Runoff = 0.01 cfs @ 22.38 firs, Volume= 0.005 af, Depth> 0.03"
Runoff by SBUH method, Split Pervious/Impew., Time Span= 0.00-32.00 hrs, dl= 0.05 hrs
Type IA 24 -hr 01-WQ Rainfall=0.83"
61.9 500 Total
Subcatchment 6S: Existing Conditions
Xydrograph
0.007'
„u=.r
- --- - - -
1.990
79 100.00%
Pervious Area
0.006
Tc Length
Slope
Velocity Capacity
Description
(min) (feet)
(ft/ft)
(f /sec) (cfs)
_Runoff Area=1.990-ac
52.4 300
0.0067
0.10
Sheet Flow,
Runoff Depth>0�3"
Grass: Dense n= 0.240 P2= 3.30"
9.5 200
0.0025
0.35
Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fos
61.9 500 Total
Subcatchment 6S: Existing Conditions
Xydrograph
0.007'
- --- - - -
Type IA 24 -hr- -- -
0.006
0'005
01-WQ Rainfall=0.83"
0.005
_Runoff Area=1.990-ac
0004
Runoff -Volume=0.005af
0.004-
Runoff Depth>0�3"
o.
Flow Length=500'-
0.aa2
Tc=61.9 min
0M.
CN=79/0
0.0m
0.001
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 19 19 20 21 22 23 24 25 26 27 28 29 30
Time (Imuml
Thurston Storm Analysis 06-30-2021 Type /A 24 -hr 01-WQ Rainfall=0.83"
Prepared by {enter your company name here} Printed 10/12/2021
HydroCAD010.10-5a sIn 04993 @2020 HydroCAD Software Solutions LLC Paae 9
Summary for Subcatchment 12S: Impervious ROW
Runoff = 0.10 cfs Cry 7.98 hrs, Volume= 0.034 af, Depth= 0.63"
Runoff by SBUH method, Split Pervious/Imperv., Time Span= 0.00-32.00 hrs, dt= 0.05 hrs
Type IA 24 -hr 01-WQ Rainfall=0.83"
Area (st CN Description
23,908 98 Impervious ROW
4,500 98 Driveways
28,408 98 Weighted Average
28,408 98 100.00% Impervious Area
Tc Length Slope Velocity Capacity Description
5.0 0 Total, Increased to minimum Tc = 10.0 min
Subcatchment 12S: Impervious ROW
0.14'
1.105:
-omm -- - -- - -- - --- -
01
Type_ IA 24 -hr
fm5
009
- 01 -WO Rainfai1=0.83"
-------_:_.. _.--------_---
6.os
Runoff Area=2&,40&sf
00
- --- RunoffVolume=0.034af
006
Runoff Depth=0.83"-
1.055
- - -
0.05Tc--10.0-min1.045-
_
0.04
- -- — - - -- -
CN=0/98
003-
1.025.
0.03.
.015
001
5 6 7 8 9 10 11 12 13 14 15 16 17 1a 19 20 21 22 23 24 25 26 27 28 29 30 31 32
Time (hours)
Thurston Storm Analysis 06-30-2021 Type IA 24 -hr 01-WQ Rainfa#=0.83"
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HydroCAD® 10.10-5a $In 04993 ® 2020 HvdraCAD Software Solutions LLC Page 10
Summary for Reach 12R: Discharge
Inflow Area = 0.652 ac,100.00% Impervious, Inflow Depth = 0.00" for 01-WQ event
Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Outflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Allen= 0%, Lag= 0.0 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-32.00 hrs, dt= 0.05 hrs
Reach 12R: Discharge
■ oumow
Inflow Area=0.652 ac
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 22 28 29 30 31 32
Tlme (hoar.)
Thurston Storm Analysis 06.30-2021 Type /A 24 -hr 01-WQ Rainfall=0.83"
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Summary for Pond 5P: Pond Tract
Inflow Area = 0.652 ac, 100.00% Impervious, Inflow Depth= 0.63" for 01-WQ event
Inflow = 0.10 cfs @ 7.98 hrs, Volume= 0.034 of
Outflow = 0.03 cfs @ 7.70 hrs, Volume= 0.034 at, Atten= 68%, Lag= 0.0 min
Discarded = 0.03 cfs @ 7.70 hrs, Volume= 0.034 of
Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Routing by Dyn-Scor-Ind method, Time Span= 0.00-32.00 hrs, dt= 0.05 hrs
Peak Elev= 521.26'@ 9.21 his Surf.Area= 564 sf Storage= 170 cf
Flood Elev= 525.90' Surf.Area= 2,638 sf Storage= 2,722 cf
Plug -Flow detention time= (not calculated: outflow precedes inflow)
Center -of -Mass det. time= 26.5 min ( 756.4 - 729.9 )
Volume Invert Avail.Storage Storage Description
#1 522.40' 2,493 cf Open Storage (Irregular)Listed below (Recalc)
#2 521.40' 32 cf Growing Medium (Irregular)Listed below (Recalc)
320 cf Overall x 10.0% Voids
#3 520.40' 197 cf Rock Chamber (Irregular)Listed below (Recalc)
564 cf Overall x 35.0% Voids
2,722 cf Total Available Storage
Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area
(feel) (sq -ft) (feet) (cubic -feet) (cubic -feet) (sq -ft)
522.40 128 61.0 0 0 128
522.90 238 87.0 90 90 436
523.90 564 127.0 389 480 1,126
524.90 995 159.0 769 1,249 1,868
525.90 1,510 183.0 1,244 2,493 2,543
Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area
(feet) (sq -ft) (feet) (cubic -feet) (cubic -feet) (sq -ft)
521.40 128 61.0 0 0 128
522.40 564 127.0 320 320 1,120
Elevation Surf.Area Perim. Inc.Store Cum.Store Wet.Area
(feet) (sq -ft) (feet) (cubic -feet) (cubic -feet) (sq -ft)
520.40 564 127.0 0 0 564
521.40 564. 127.0 564 564 691
Device Routing Invert Outlet Devices
#1 Discarded 520.40' 2.500 in/hr Exfihration over Surface area
#2 Primary 521.48' 12.0" Round 12" Pipe
L= 180.0' RCP, rounded edge headwall, Ke= 0.100
Inlet/ Outlet Invert= 521.48'/ 520.94' S= 0.0030'1' Cc= 0.900
n= 0.011, Flow Area= 0.79 sf
#3 Device 2 523.40' 1.5" Vert. 1.5" Orifice C= 0.600 Limited to weir flow at low heads
#4 Device 2 523.90' 2.0" Vert. 2" Orifice C=0.600 Limited to weir flow at low heads
#5 Device 2 525.40' 24.0" W x 24.0" H 180 24" Grate C= 0.600
Limited to weir flow at low heads
Thurston Storm Analysis 06-30-2021 Type /A 24 -hr 01-WQ Rainfall=0.83"
Prepared by {enter your company name here} Printed 10/12/2021
HydroCADO 10.10-5a s/n 04993 ® 2020 HydroCAD Software Solutions LLC Pace 12
Discarded OutFlow Max=0.03 cfs @ 7.70 hrs HW=520.49' (Free Discharge)
L1=Exfiltration (Exfiltration Controls 0.03 cfs)
Primary OutFlow Mx=
a0.00 cfs @ 0.00 hrs HW=520.40' TW=0.00' (Dynamic Tailwater)
L2-3' Pipe ( Controls 0.00 cfs)
3=1.5" Orifice ( Controls 0.00 cfs)
=2" Orifice ( Controls 0.00 cfs)
=24" Grate ( Controls 0.00 cfs)
Pond 512: Pond Tract
Inflow Area=0.6-$2-ac-
:PDrertlry
011
- -- --
° o;,
Peak Elev=5211.26'
ON
- - Storage_170-cf
9.995
0.9e
-- -- - -- - -
0.075.
0.07
v 0.085
- - - - - -
ON
- - - -
�Oa85.
am
LL
0.045
oa4.
9.035
-- - - -
0.03
0.025.
- - - - -
0.02
0.015
0.01
00-
0
0 1
2 3 4 5 6 7 8 91011121314151617181920212223242526272829303132
lime (wum)
Thurston Storm Analysis 06-30-2021 Type /A 24 -hr 02-2 Year Rainfall=3.30"
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Time span=0.00-32.00 hrs, dt=0.05 hrs, 641 points
Runoff by SBUH method, Split Pervious/Imperv.
Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Scor-Ind method
Subcatchment6S: Existing Conditions Runoff Area=1.990 ac 0.00%Impervious Runoff Depth>1.41"
Flow Length=500' T0=61.9min CN=7910 Runoff=0.29 cfs 0.234 of
Subcatehmentl2S: Impervious ROW Runoff Area=28,408 sf 100.00% Impervious Runoff Depth=3.07"
Tc=10.0 min CN=0/98 Runoff -0.48 cis 0.167 of
Reach 12R: Discharge
Inflow=0.14 cfs 0.028 of
Outflow=0.14 cfs 0.028 of
Pond 5P: Pond Tract Peak Elev=524.52' Storage=1,131 of Inflow=0.48 cis 0.167 of
Discarded=0.11 cfs 0.139 of Primary=0.14 efs 0.028 of Outflow=0.25 cls 0.167 of
Total Runoff Area = 2.642 ac Runoff Volume = 0.401 of Average Runoff Depth = 1.82"
75.32% Pervious = 1.990 ac 24.68% Impervious = 0.652 so
Thurston Storm Analysis 06-30-2021 Type /A 24 -hr 02-2 YearRainfali=3.30"
Prepared by {enter your company name here} Printed 10/12/2021
HydroCADV 10.10-5a a/n 04993 02020 HydroCAD Software Solutions LLC Pace 14
Summary for Subcatchment 6S: Existing Conditions
Runoff = 0.29 cfs @ 8.37 hrs, Volume= 0.234 af, Depth> 1.41"
Runoff by SBUH method, Split Pervious/Imperv., Time Span= 0.00-32.00 hrs, dt= 0.05 hrs
Type IA 24 -hr 02-2 Year Rainfall=3.30"
I.UWU 1a raslureigrasslanairange, Hoor, Fish t1
1.990 79 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
DLR 3UU u.Vuor U. IV unee[rlow,
Grass: Dense n= 0.240 P2= 3.30"
9.5 200 0.0025 0.35 Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fos
Total
Subcatchment 6S: Existing Conditions
os
C
0,28
026
024
0.22
0.2
L 018
0.16
014
0.12
0.1
0.08
006
0.04
0.02
OD
0 1 2
3
4 5
6
8
`type IA 24 -hr
02-2 Year Rainfall=3.30_'-
--Runoff Area=1.990 ac
Runoff Volurrle=0.234 ai
Runoff Depth>IAI"-
Flow tength=500'
Tc=61.9 min_
CN=7910
10 11 12 13 14 16 16 1 .. ..,
T 18 19 20 21 22 23 24 25 26 2J 26 29 3a 31 32
TI111G (hOV(S)
■ftunoR
Thurston Storni Analysis 06-30-2021 Type /A 24 -hr 02-2 YearRainfall=3.30"
Prepared by {enter your company name here} Printed 10/12/2021
HydroCAD®10.10-5a s/n 04993 02020 HydroCAD Software Solutions LLC Pace 15
Summary for Subcatchment 12S: Impervious ROW
Runoff = 0.48 cfs @ 7.98 hrs, Volume= 0.167 af, Depth= 3.07'
Runoff by SBUH method, Split Pervious/Imperv., Time Span= 0.00-32.00 hrs, dt= 0.05 hrs
Type IA 24 -hr 02-2 Year Rainfall=3.30"
Tc Length Slope Velocity Capacity Description
to minimum Tc = 10.0 min
Subcatchment 12S: Impervious ROW
Hvdmaraah
0.5
0.4.5
0.4
0.35
U 0.3
3o 0.25
n 0.2
0.15
0.1
0.05
a
0 1 2 3 4 5 6 7 0 910
1[ la 1 10 a IY 1V 11 GG L] GV 1] 1tl 11 Ztl 29 3u !1 32
Time
hours)
■auno0
0.Yai
Type IA 24 -hr
02-2 Year Rainfall=3.30"
Runoff Area=28,40&sf
Runoff Volume=0.167 of
R-unoff Depth=3.OT'
Tc=10.0 min
CN=0/98
a
0 1 2 3 4 5 6 7 0 910
1[ la 1 10 a IY 1V 11 GG L] GV 1] 1tl 11 Ztl 29 3u !1 32
Time
hours)
■auno0
Thurston Storm Analysis 06-30-2021 Type /A 24 -hr 02-2 YearRaMWI=3.30"
Prepared by {enter your company name here} Printed 10/12/2021
HydroCAD®10.10-5a s/n 04993 02020 HydroCAD Software Solutions LLC Pace 16
Summary for Reach 12R: Discharge
Inflow Area = 0.652 ac,100.00% Impervious, Inflow Depth= 0.57' for 02-2 Year event
Inflow = 0.14 cfs @ 8.42 hrs, Volume= 0.028 of
Outflow = 0.14 cfs @ 8.42 hrs, Volume= 0.028 af, Atten= 0%, Lag= 0.0 min
Routing by Dyn-Scor-Ind method, Time Span= 0.00-32.00 hrs, dt= 0.05 hrs
Reach 12R: Discharge
Xydmgraph
0.15 '- _ __ - -. ____ _ Ma -
D.14 - " - -Inflow -Area=fL652-ac
0.13- - - _---- -- -"
D.ts
0,11
0.1
0.09
0.08 -- - - - -- -
0 0.07
LL 0.06-
oas.
0.04
0.03
Thurston Storm Analysis 06-30-2021 Type /A 24 -hr 02-2 Year Rainfall=3.30"
Prepared by {enter your company name here) Printed 10/12/2021
HydroCAD010.10-5a s/n 04993 02020 HydroCAD Software Solutions LLC Pane 17
Summary for Pond 5P: Pond Tract
Inflow Area = 0.652 ac,100.00% Impervious, Inflow Depth= 3.07" for 02-2 Year event
Inflow =
0.48 cis @
7.98 hrs,
Volume=
0.167 of
Outflow =
0.25 cfs @
8.42 hrs,
Volume=
0.167 af, Atlen= 48%, Lag= 26.5 min
Discarded =
0.11 cis @
8.42 hrs,
Volume=
0.139 of
Primary =
0.14 cis @
8.42 hrs,
Volume=
0.028 of
Routing by Dyn-Stor-Ind method, Time Span= 0.00-32.00 hrs, dt= 0.05 hrs
Peak Elev= 524.52'@ 8.42 hrs Surf.Area= 1,943 sf Storage= 1,131 cf
Flood Elev= 525.90' Surf.Area= 2,638 sf Storage= 2,722 cf
Plug -Flow detention lime= 72.0 min calculated for 0.166 of (100% of inflow)
Center -of -Mass det. time= 72.1 min ( 742.7 - 670.6 )
#1 522.40' 2,493 cf
Open Storage (Irregular)Listed below (Recalc)
#2 521.40' 32 cf
Growing Medium (Irregular)Listed below (Recalc)
Wet.Area
320 cf Overall x 10.0% Voids
#3 520.40' 197 cf
Rock Chamber (Irregular)Listed below (Recalc)
(cubic -feet)
564 cf Overall x 35.0% Voids
2,722 of
Total Available Storage
Elevation
Surf.Area Perim.
Inc.Store
Cum.Store
Wet.Area
(feet)
(sq -ft)
(feet)
(cubic -feet)
(cubic -feet)
(sq -ft)
522.40
128
61.0
0
0
128
522.90
238
87.0
90
90
436
523.90
564
127.0
389
480
1,126
524.90
995
159.0
769
1,249
1,868
525.90
1,510
183.0
1,244
2,493
2,543
Elevation
Surf.Area Perim.
Inc.Store
Cum.Stom
Wet.Area
(feel)
(sq -ft)
(feet)
(cubic -feet)
(cubic -feet)
(sq -ft)
521.40
128
61.0
0
0
128
522.40
564
127.0
320
320
1,120
Elevation
Surf.Area Perim.
Inc.Store
Cum.Store
Wet.Afea
(feet)
(sq -ft)
(feet)
(cubic -feet)
(cubic -feet)
(soft)
520.40
564
127.0
0
0
564
521.40
564
127.0
564
564
691
Device Routing
Invert
Outlet Devices
#1 Discarded 520.40'
2.500 in/hr Exfiltration
over Surface area
#2 Primary
521.48'
12.0" Round 12" Pipe
L= 180.0'
RCP, rounded edge headwall, Ke= 0.100
Inlet/ Outlet Invert= 521.48'/
520.94' S=0.00307 Cc= 0.900
n= 0.011,
Flow Area= 0.79
sf
#3 Device 2
523.40'
1.5" Vert.
1.5" Orifice
C=0.600 Limited to
weir flow at low heads
#4 Device 2
523.90'
2.0" Vert.
2" Orifice C=0.600 Limited to weir flow at low heads
#5 Device 2
525.40'
24.0" W x 24.0" H 18° 24" Grate C= 0.600
Limited to weir flow at low heads
Thurston Stone Analysis 06-30-2021 Type (A 24 -hr 02-2 YearRarnfall=3.30"
Prepared by (enter your company name here) Printed 10/12/2021
HydroCAD®10.10-5a s/n 04993 02020 HydroCAD Software Solutions LLC Pace 18
Discarded OutFlow Max=0.11 cfs @ 8.42 hrs HW=524.51' (Free Discharge)
t-1=Exfiltration (Exfiltration Controls 0.11 cfs)
Primary OutFlow Max=0.14 cfs @ 8.42 hrs HW=524.51' TW=0.00' (Dynamic Tailwater)
t2=12" Pipe (Passes 0.14 cfs of 4.46 cfs potential flow)
1.5" Orifice (Orifice Controls 0.06 cfs @ 4.94 fps)
=2" Orifice (Orifice Controls 0.08 cfs @ 3.51 fps)
=24" Grate ( Controls 0.00 cfs)
Pond SP: Pond Tract
■ inaw
oM� Inflow A rea=0.652- aic •°
■ Pnmery
- Peak Elev=524.52'
Storage --1,131 cf
� 03l
0.25 OR
LL
0.1
0 1 2 3 4 5 6 7 8 9 18 11 12 13 14 15 16 1718 19 20 21 22 23 24 25 26
Time fhours)
Thurston Storm Analysis 06-30-2021 Type IA 24 -hr 03-25 YearRainfall=4.80"
Prepared by {enter your company name here} Printed 10/12/2021
HydroCAD®10.10-5a s/n 04993 @2020 HydroCAD Software Solutions LLC Pace 19
Time span=0.00-32.00 hrs, dt=0.05 hrs, 641 points
Runoff by SBUH method, Split Pervious/Imperv.
Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method
Subcatchment6S: Existing Conditions Runoff Area=1.990 ac 0.00%Impervious Runoff Depth>2.63"
Flow Length=500' Tc=61.9 min CN=7910 Runoff --0.63 cfs 0.436 of
Subcatchment128: Impervious ROW Runoff Area=28,408sf 100.00%Impervious Runoff Depth=4.56"
Tc=10.0 min CN=0/98 Runoff=0.70 cfs 0.248 of
Reach 12R: Discharge
Inflow=0.19 cis 0.072 of
Outflow=0.19 cfs 0.072 of
Pond 5P: Pond Tract Peak Elev=525.16' Storage=1,753 cf Inflow=0.70 cis 0.248 of
Discarded=0.13 cfs 0.176 of Pdmary=0.19 cfs 0.072 of Outflow=0.32 cfs 0.248 of
Total Runoff Area= 2.642 ac Runoff Volume= 0.684 of Average Runoff Depth= 3.11"
75.32% Pervious= 1.990 ac 24.68% Impervious = 0.652 ac
Thurston Storm Analysis 06-30-2021 Type /A 24 -hr 03-25 Year Rainfall=4.80"
Prepared by (enter your company name here) Printed 10/12/2021
HydroCAD® 10.10-5a s/n 04993 ® 2020 HydroCAD Software Solutions LLC Pace 20
Summary for Subcatchment 6S: Existing Conditions
Runoff = 0.63 cfs @ 8.28 hrs, Volume= 0.436 af, Depth> 2.63"
Runoff by SBUH method, Split Pervious/Imperv., Time Span= 0.00-32.00 hrs, dt= 0.05 hrs
Type IA 24 -hr 03-25 Year Rainfall=4.80"
Area (ac) CN Description
1.990 79 Pasture/grassland/range Poor HSG B
1.990 79 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (f /ft) (ft/sec) (cfs)
52.4 300 0.0067 0.10 Sheet Flow,
Grass: Dense n= 0.240 P2= 3.30"
9.5 200 0.0025 0.35 Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fos
61.9 500 Total
Subcatchment 6S: Existing Conditions
0.7
_ _ _
■RunWf
0.65
-- - - -- - --- - -Type [A 24 -hr
0.6
5.55-
-Q3-25Yeal•Ranfatl=4.8p"
9.5
_
_ _ .Runoff Area=1.990ac
045
_ _
Runoff Volume=0.436 of
°°
Runoff Depth>2.63"
0.36
Flow Length=500'
u 0.3
_ --Tc=61.9mirt-
0.25
0.2
- --- ----CW7910-
0.15-
0.1
8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Thurston Storm Analysis 06-30-2021 Type IA 24 -hr 03-25 Year Rainfall=4.80"
Prepared by {enter your company name here} Printed 10/12/2021
HydroCAD®10.10-5a s!n 04993 0 2020 HydroCAD Software Solutions LLC Paw 21
Summary for Subcatchment 12S: Impervious ROW
Runoff = 0.70 cfs @ 7.98 hrs, Volume= 0.248 af, Depth= 4.56"
Runoff by SBUH method, Split Perviousflmperv., Time Span= 0.00-32.00 hrs, dt= 0.05 hrs
Type IA 24 -hr 03-25 Year Rainfall=4.80"
Area (sf CN Description
` 23,908 96 Impervious ROW
4,500 98 Driveways
28,408 98 Weighted Average
28,408 98 100.00% Impervious Area
Tc Length Slope Velocity Capacity Description
0 Total, Increased to minimum Tc = 10.0 min
Subcatchment 12S: Impervious ROW
■ RunoR
0.]
TYPe IA -24 -hr
03-25 Year Rainfall=4.80"
03
OW Runoff Are&28,408 sf
06- Runoff volume=0.248 of
Runoff Depth=4.56'
LL o.35
Tc=10.O min
03 CN=0/98
or
0.15
0.1
0.
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 15 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
Time (hours)
Thurston Storm Analysis 06-30-2021 Type /A 24 -hr 03-25 Year Rainfall=4.80"
Prepared by {enter your company name here} Printed 10/12/2021
HydroCA0010.10-5a s/n 04993 02020 HydroCAD Software Solutions LLC Page 22
Summary for Reach 12R: Discharge
Inflow Area = 0.652 ac,100.00% Impervious, Inflow Depth = 1.32" for 03-25 Year event
Inflow = 0.19 cfs @ 8.52 hrs, Volume= 0.072 of
Outflow = 0.19 cfs @ 8.52 hrs, Volume= 0.072 af, Atten= 0%, Lag= 0.0 min
Routing by Dyn-Stor-Ind method, Time Span= 0.00-32.00 hrs, dt= 0.05 hrs
Reach 12R: Discharge
M
0 1 2 3 4 5 fi ] 8 9 10 it 12 13 id 15 16 iZ 18 19 20 21 22 23 24
- _, ' - - - -
■In0ow
0.21
°"" -Inflow Area=0.652-ac
os
o,a
916.
-- - ------ �-
015-
_ - ---- --
014
a,a'
012-
- - _- - - - -
0.11
01"
0.09--
-
o.ofi:
- __ - ..-- - - - -- .....
007
0.as
005-
0
M
0 1 2 3 4 5 fi ] 8 9 10 it 12 13 id 15 16 iZ 18 19 20 21 22 23 24
Thurston Storm Analysis 06-30-2021 Type /A 24 -hr 03-25 YearRarnfall=4.80"
Prepared by (enter your company name here) Printed 10/12/2021
HydroCAD®10.10-5a s/n 04993 ® 2020 HydroCAD Software Solutions LLC Paas 23
Summary for Pond 5P: Pond Tract
Inflow Area = 0.652 ac, 100.00% Impervious, Inflow Depth = 4.56" for 03-25 Year event
Inflow = 0.70 cfs @ 7.98 hrs, Volume= 0.248 of
Outflow = 0.32 cfs @ 8.52 hrs, Volume= 0.248 af, Atten= 54%, Lag= 32.6 min
Discarded = 0.13 cfs @ 8.52 hrs, Volume= 0.176 of
Primary = 0.19 cfs @ 8.52 hrs, Volume= 0.072 of
Routing by Dyn-Stor-Ind method, Time Span= 0.00-32.00 hrs, dt= 0.05 hrs
Peak Elev= 525.16'@ 8.52 hrs Surf.Area= 2,247 at Storage= 1,753 cf
Flood Elev= 525.90' Surf.Area= 2,638 sf Storage= 2,722 cf
Plug -Flow detention time= 79.5 min calculated for 0.248 of (100% of inflow)
Center -of -Mass det. time= 79.7 min ( 741.4 - 661.7 )
Volume Invert Avail.Storage Storage Description
#1 522.40' 2,493 cf Open Storage (Irregular)Listed below (Recalc)
#2 521.40' 32 cf Growing Medium (Irregular)Listed below (Recalc)
320 of Overall x 10.0% Voids
#3 520.40' 197 of Rock Chamber (irregular)Listed below (Recalc)
564 cf Overall x 35.0% Voids
cf Total Available Storage
Elevation
SUrf.Area Perim.
Inc.Store
Cum.Store
Wet.Area
(feel)
(sq -ft)
(feet)
(cubic -feet)
(cubic -feet)
(sq -ft)
522.40
128
61.0
0
0
128
522.90
238
87.0
90
90
436
523.90
564
127.0
389
480
1,126
524.90
995
159.0
769
1,249
1,868
525.90
1,510
183.0
1,244
2,493
2,543
Elevation
Surf.Area Perim.
Inc.Store
Cum.Store
Wet.Area
(feet)
(sq -ft)
(feet)
(cubic -feet)
(cubio-feet)
(sq -fl)
521.40
128
61.0
0
0
128
522.40
564
127.0
320
320
1,120
Elevation
Surf.Afea Perim.
Inc.Stors
Cum.Store
Wet.Area
(feel)
(sq -ft)
(feet)
(cubic -feet)
(cubic -feet)
(sq -fl)
520.40
564
127.0
0
0
564
521.40
564
127.0
564
564
691
Device Routing
Invert
Outlet Devices
#1 Discarded 520.40'
2.500 in/hr Exfiltration
over Surface area
#2 Primary
521.48'
12.0" Round 12" Pipe
L= 180.0'
RCP, rounded edge headwall, Ke=
0.100
Inlet/Outlet
Invert= 521.48'/
520.94' S=0.0030'/' Cc= O.900
n= 0.011,
Flow Area= 0.79
sf
#3 Device 2
523.40'
1.5" Vert.
1.5" Orifice
C=0.600 Limited to
weir flow at low heads
#4 Device 2
523.90'
2.0" Vert.
2" Orifice C=0.600
Limited to weir flow at low heads
#5 Device 2
525.40'
24.0" W x 24.0" H 18° 24" Grate C= 0.600
Limited to weir flow at low heads
Thurston Storm Analysis 06-30-2021 Type /A 24 -hr 03-25 Year Rainfa/1=4.80"
Prepared by (enter your company name here} Printed 10/12/2021
HydroCAD®10.10-5a s/n 04993 @ 2020 HydroCAD Software Solutions LLC Page 24
Discarded OutFlow Max=0.13 cfs @ 8.52 hrs HW=525.16' (Free Discharge)
t-1=Exfiltration (Exfillration Controls 0.13 cfs)
Primary OutFlow Max= -0.19 cfs @ 8.52 hrs HW=525.16' TW=0.00' (Dynamic Tailwater)
'L2=12" Pipe (Passes 0.19 cfs of 4.99 cfs potential flow)
3=1.5" Orifice (Otifice Controls 0.08 cfs @ 6.27 fps)
=2" Orifice (Orifice Controls 0.11 cfs @ 5.22 fps)
=24" Grate ( Controls 0.00 cfs)
Pond 5P: Pond Tract
Rom
-
Inflow /krea=0.652
ac
0.75
Peak Elev=525.16'
o,
0.0
-- - �- - -Storage=1;753 cf
0.6-
- - -. - - - -
US
E OAS
-
00-
a
u
0.3
0.25
nes
Rom
July 16, 2021
Jed Truett
Metro Planning, Inc.
846 A Street, Springfield, OR
ied@metroolannine.com
RE: SITE INFILTRATION TEST RESULTS
7399 THORSTON ROAD
EUGENE, OREGON 97402
BRANCH ENGINEERING INC PROJECT NO. 21-412
Branch
E-NIGINEERING:
5lnce ter,
Branch Engineering Inc. (BEI) has performed infiltration testing in one hand -auger test hole
located in the area of a proposed pond infiltration facility; see Infiltration Testing Map, Figure 1,
for approximate location of the test. The purpose of our testing was to provide a site-specific
infiltration rate for the design of on-site infiltration facilities for the disposal of stormwater
generated from new impervious surface areas.
Field Work and Site Description
One approximately 8 -inch diameter hand -auger hole was advanced to a maximum depth of 42 -
inches below ground surface (BGS) and pre -saturated with water on July 14, 2021. On July 1.5,
2021, a Falling Head Infiltration Test was performed in accordance with the 2014 City of Eugene
Stormwater Manual. Infiltration testing of the 6 -inch diameter cased holes commenced for three
successive trials with water added between each trial; field data is attached.
At the time of testing, the site had one existing residence in the northern extent of the lot, with
associated garages and storage buildings located throughout the property. The central and
southern portions of the lot were unmaintamed, with tall unmoved grasses and vegetation
growing on the majority of the property.
soils
The soil in the test hole was visually classified using the American Society of Testing and
Materials (ASTM) Method 1-2488. Soil conditions at the location of Infiltration Test 1 (IT1)
consisted of a topsoil horizon of soft, light brown silt with roots and gravel from approximately
0- to 4 -inches BGS, followed by a layer of loose medium brown clayey silt with medium plasticity
from 4- to 36 -inches BGS. This was underlain by a layer of loose, tan -brown sandy silt from 36 -
to 42 -inches BGS.
The NRCS Web Soil Survey maps the site entirely as Chapman -Urban land complex (25). This soil
unit is described as well drained and derived from alluvium from mixed sources. Field log
summaries and nearby well logs are attached, indicating subsurface conditions are consistent
with our observations.
Groundwater
Ground water was not encountered in the site borings, and a well log on the northeastern -
adjacent property indicates static groundwater levels at 11 -feet below the surface; see attached
well logs. A 5 -foot buffer is generally recommended between the bottom of the soakage trench
and recorded static high groundwater level.
p:503-779-2577 I www. branchen gi neering. com
7399 Thurston Road, Eugene
BEI PN 21-412
Summary of Field Infiltration Test Results
The results of our July 15, 2021 field testing are summarized below in Table 1. The hydraulic
conductivity is based on the infiltration rates measured in the field and summarized on the
attached Infiltration Testing Field Data. The rates shown below have no factors of safety applied
and represent the slowest infiltration rate measured of the three trials.
Table 1:
Location
Depth of Test
Measured Rate of Hydraulic
(In)
Conductivity, k (in/hr)
IT -1
42
16.5
Recommended Infiltration Design Rates
Using the recommended factor of approximately safety of 2, a design infiltration rate of 8 in/hr
is suggested for development on this site. Safety factors may be applied at the discretion of the
designer and the 2014.City of Eugene Stormwater Manual.
Conclusions
Based on our field findings and infiltration testing results, disposal of stormwater via infiltration
facilities on the site is feasible.
If you have any questions regarding the test method, data analysis or design, please contact the
undersigned.
Sincerely,
Brunch Engineering Inc,
F9
#16,170��
OREGON
'P6SF'oT15,
ygCA7. o�P
FXPIRES:12/31/2021
Ronald Derrick P.E. G.E.
Principal Geotechnical Engineer
Attached:
Figure -1 Infiltration Testing Map
Infiltration Testing Field Data
MRCS Site Soil Mapping
Nearby Well Logs
Branch Engineering, Inc
anch
INEERING�
1.ltoajera739 iauaaan Ruas
Projat 7399 .7/15g 0 Rwd Etgm¢ Oregou
TU W.jL9te Ifea,. 21
BD Rojed Wrmbs. LY912
1 eat 1-0 a adeRtiJ Falling H�aJ In fillratlon
r �=neramlrIlhl Hzo
fu®tratl®Test l lYWl l
pse Ilhl....
Time (miu) Mu[ere(Ip)
Rot a
(lymlo)
(N/hl)
As Rate of Fall T 1(m )
stets i Hlameler(e
5
0 395
1dI
Stand f He ht—(it) i8
2 400 20.0 025 iso
Terlll. Nla, ", 42
5 41.5 As 050 30.0
Volvmc of Nater eRo,I al 2
10 438 16.3 0..15 220
Cloektlme at Ilan 12'.32
20 460 14.0 023 13.5
214
ASTAISWIT (MH
mlu®tleat at l It1ol2
pae ffer rowa"" cp alar o [a wren F
Time([mn) smfaae0o) (io) (wane, flag)
Avg Rate of Fell T-2 m/br)
Vomme of wait' Aaaea ail
1
0 30.0
21.0
Qot$ime 131W
- 4L5 18.5 O.AI 300
10 43.3 16a 035 210
20 453 lab 020 12.0
165
WHIVatlon Tm(1 irial3
MIT,Depth oR Rote,Rate
Iime fmlul Aurlee'n (ire (a) (la/mi, Ga/hr)
A Rate of Pell T-4 R.Ala)
Volume of watt, -1. ap
1
0 380
22.0
It.'Wme 1332i
239.0 21. OW 300
4 3Y5 295 025 ]50
to I 420 ]80 042 25.0
zo450 15.0 030 1a0
25 43.3
118
025
1'0
18.5
Rateco Wever Leiel Pell iraff,
o s an �,nh m n m
Soil Map—Lane County Area, Oregon
(21-012 soil map)
mono se � oam � sero mem servo maw
a
p f'�`�-': 1:1,llOSph �mApotrtl[(e5'x ll')SMN. '�
p Nan p
q N 0 15 3l ® 9p
A o
0 `A 1W 3p
Nap Grvk'aMn: NkU Mc[&II CVlrxm�NM®: NG581 Cb#Y :111MZ lOn NGS&1
Sim Natural Resources Web Soil Survey 7/13/2021
Conservation Service Nabonal Cooperative Soil Survey Pagel of3
�
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Soil Map—Lane County Area. Oregon
Map Unit Legend
21412 soil map
I�Sps Natural Resources Web Soil Survey 7/132021
i Conservation Service National Cooperative Soil Survey Page 3 of
Map Unit Symbol
Map Unit Name
Acres in AOI
Percent of AOI
25
118
Totals for Area of Interest
Chapman -Urban land complex
Salem gravelly silt loam
4.9
0.0
0.9
99.9%
0.1%
100.0%
I�Sps Natural Resources Web Soil Survey 7/132021
i Conservation Service National Cooperative Soil Survey Page 3 of
Map Unit Oescnpron: Chapman -Urban land complex ---Lane County Area, Oregon 25 soil description
Lane County Area, Oregon
25—Chapman-Urban land complex
Map Unit Setting
National map unit symbol., 2360
Elevation: 300 to 1,000 feet
Mean annual precipitation: 40 to 60 inches
Mean annual air temperature: 52 to 54 degrees F
Frost -free period: 165 to 210 days
Farmland classification: Farmland of statewide Importance
Map Unit Composition
Chapman and similar soils: 45 percent
Urban land. 40 percent
Estimates are based on observations, descriptions, and transects of
the mapunit.
Description of Chapman
Setting
Landfomr: Stream terraces
Landform position (three-dimensional): Tread
Down-slope shape: Linear
Across -slope shape. Linear
Parent material., Alluvium from mixed sources
Typical profile
Hf - 0 to 8 inches: loam
H2 - 8 to 42 inches: loam
H3 - 42 to 50 inches: gravelly sandy loam
H4 - 50 to 60 inches., very gravelly sandy loam
Properties and qualities
Slope: 0 to 3 percent
Depth to restrictive feature: More than 80 inches
Drainage class: Well drained
Capacity of the most limiting layer to transmit water
(Ksat): Moderately high to high (0.57 to 1.98 inlhr)
Depth to water table., More than 80 inches
Frequency oftloordng. RareNone
Frequency ofponding. None
Available watercapacity: Moderate (about 8.1 inches)
Interpretive groups
Land capability classification (irrigated): 1
Land capability classificabon (nonirrigated): 1
Hydrologic Soil Group., 8
Forage suitability group., Well drained < 15% Slopes
(G002XY0020R)
Othervegetative classification: Well drained < 15% Slopes
(GCO2XY0020R)
nr11 Natural Resources Web Soil Survey 7/13/2021
i Conservation Service National Cooperative Soil survey Page 1 of 2
Map Unit Description: Chapman -Urban land complex --Lane County Area, Oregon 25 soil description
Hydric soil rafing. No
Description of Urban Land
Properties and qualities
Slope. 0 to 3 percent
Frequency of floor6ng. RareNone
Interpretive groups
Land capability classification(in'igated): Nonespecifed
Land capability classification (nonirrigated): 8
Hydric soil rating: No
Data Source Information
Soil Survey Area: Lane County Area, Oregon
Survey Area Data: Version 17, Jun 11, 2020
1� Natural Resources Web Soil survey 71132021
Conservation Service National Cooperative Soil Survey Page 2 of 2
�;�0�
STATE OF OREGON - 1
WATER SUPPLY WELLREPORT
(xwW' by W833 7"
(1) OWNER: Well Nu
N. Rick Maberry
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Sp.dd Camhu4an.ppm.4 ❑YWXN. D*ffi dCmp[dW %H A( _R
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COPY -CUSTOMER
SPRINGFIELD
DEVELOPMENT AND PUBLIC WORKS 1901 225 FIFTH ST
REET
OREGON SPRINGFIELD, OR 97477
PHONE 541.726.3753
FAX: 541.726.1021
www.springfield-or.gov
STORMWATER MANAGEMENT SYSTEM SCOPE OF WORK
__ ----- —__------ —_____________—__ (Area belaw this line filled out by Applicant)
(Please return to Clayton McF,aehem (a, City ofSprfrtgJield Development and Public Works, Far 4 736-1021, Phone 4 736-1036),
email: cmceachern@springfield-oegov
Protect Name: Thurston Road Subdivi cion Annlirant. A&O Engineering, LLC
Assessors Parcel #: 17-02-35-00-02700 Date: 06/22/2021
Land Use(s): Single Family Residential Phone #: (541)302-9790
Project Size (Acres): 1.99 Fax #:
Approx. Impervious Area: 1.5 acres Email: kylemoms@ao-enc .coni
Project Description (Include a copy of Assessor's map):
Construct single family residential subdivision with publicly owned roadways and necessary utilities.
Drainage Proposal (Public connection(s), discharge location(s), etc. Attach additional sheet(s) if necessary:
It is proposed to construct new storm main along Thurston Road west of the site and connect into existing public
storm piping/curb inlets at the northwest corner of the Elementary School (schematic attached).
Proposed Stormwater Best Management Practices:
Stormwater on-site is proposed to be collected via curb inlets and piping and treated via either street bumpout
planters or common stormwater pond within tract. Design details to be dialed in once infiltration testing is
completed.
--------- (Area below this line billedow by theCity d Ref d t th A a!i ra) ------__—
(At a minimum, all boxes checked by the City on the front and back ofthis sheet shall be submitted
or an a lication to be complete for submittal, although other re « irements m,ry be necessa .
Drainage Study Type (EDSPM Section 4.03.2) (Note. UH may be substituted for Rational Method)
❑ Small Site Study — (ace Rational Method for calculations)
Mid -Level Development Study — lase Unit Hydrograph Method for calculations)
❑ Full Drainage Development Study — (use Unit Hydrograph Method for calculations)
Environmental Considerations:
E]❑HiWellhead Zone: 20 year time of travel n/a
llside Development:
❑ Wetland/Riparian: ❑ Floodway/Floodplain:—
❑ Soil Type: 25 Chapman Hydrologic group n ❑ Other Jurisdictions ane oun y or
�
Downstream Analysis:
in onRElnfiltration or detention used to limit
V N/A runoff
❑ Flow line for starting water surface elevation:
F-1Design HGL to use for starting water surface elevation:
❑ Manhole/Junction to take analysis to:
�
county portion of
hThurston road
Return to Clayton McEachern @ City of Springfield, email: cmceachern@springfield-or gov, FAX: (541) 776.1021
COMPLETE STUDY ITEMS
a Rased upon she in/mvnatian prm'iJed ore the fit w of lhi.s sheet. 1he (ollmving repreceats a ,nminrum q1 n=hm is needed. jw an
application to be enmplelefo, svlvnwal a-uh respect to dninagc: hwrer, er, this $fl shmdd nor be used it, net, ofthe Springfield
De ,clapn'enr Code rSDCI or the Cm's EngirteeringDesign MarmaL Compliance with these rrquirentents does not constitute site
approwl. Additional site speeific in1amialiotnam be required. ,Yate: Upau scoping.shretsubaunral ensure completed fora' bas been
signed in the space prm'ided helou':
InterLn Desi Standards!\Vater Quality (F:DSPM Chapter 3
Req'd N/A
All non -building rooftop (N BR) impervious surfaces shall be pre-treated (e.g, multi-chambered catchbasin w/oil filtration
medial for stotmwater quality. Additionally, a minimum of50%ofthe NBR impervious surface shall be treated by
vegetated methods.
Where required, Vegetative stornnvater design shall be consistent with design standards (EDSPM Section 3.02), set forth
in Chapter 2 of the Eugene Stomrwater Management Manual
E]❑ For new NBR impervious area less than 15,000 square feet, a simplified design approach may be followed as specified
by the Eugene Stommater Management Manual (See2A.I).
E] Fj IN smmnvatm weatment 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 Slormwnter Management Manual.
E] E] Waiter Quality calculations as mprired in Section 3.03.1 ofthe EDSPM.
All building rooftop mounted equipment, or other fluid containing equipment located outside of the budding, shall
Lj ❑ Drainage Study prepared by a Professional Civil Engineer licensed in the state of Oregon.
QF-1 A complete drainage study. as required in EDSPM SW.iou 4.03.1, including a hydrological study map.
Calculations showing system capacity for a 2 -year norm event and overflow effects of a 25 -year storm event.
E] ❑ The time of mncentration (TO shall be determined using a 10 minute start time fm developed basins.
°This form shall be included as an attachment, inside the front cover, of the starmwarer study.
" IMPORTANT.- ENGINEER PLEASE READ BELOW AND SIGN.'
As the engineer of record, 1 hereby certify the above
/required �'zterns�yanre c_omplem and included with the submitted stomtwater study
and plan set. Signature r7" t " t9r��7` Date l° bi ja
Form Version S: .lune 2015
A downstream drainage analysis as described in EDSPM Section 4.03A.C. On-site drainage shall be governed by the
Oregon Plumbing Specialty Code (OPSC).
M
❑
Elevations of the HGL and now lines for both city and private systems where applicable.
❑
❑
Design of Storm Systems (EDSPM Section 4.04).
❑
❑
Flow lines, slopes. rim elevations, pipe type and sizes clearly indicated on the plan set.
❑
❑
Minimum pipe weer 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 60,000 Ib load
without failure of the pipe structure.
❑
Manoing's "n" values for pipes shall be consistent with Table 4-1 of the EDSP..All storm pipes shall be designed m
achieve a minimum velocity of three 13) feet per second at 0.5 pipe full based on Table 4-1 as well.
Other(Miseelieneous
Existing and proposed contours, located at one foot interest. Include spot elevations and site grades showing how site
drains.
Private stormwater casements shall be clearly depicted on plans when private swrmwater flows from one property to
anodrer-
D 3mvIls shall not receive runoff from any surface w!o being treated by one or more BMPs; with the exception of
residential buildingroofs (EDSP Section 3.03,4.A). Additional provisions apply to this as required by the DEQ. Refer to
the website: run'itw dea.smte.or.us/ivqluicluic-him for more information.
F]
[j
[Mention ponds shall be designed to limit mnoff to pre -development rates for the 2 through 25 -year storm events.
or infiltration
°This form shall be included as an attachment, inside the front cover, of the starmwarer study.
" IMPORTANT.- ENGINEER PLEASE READ BELOW AND SIGN.'
As the engineer of record, 1 hereby certify the above
/required �'zterns�yanre c_omplem and included with the submitted stomtwater study
and plan set. Signature r7" t " t9r��7` Date l° bi ja
Form Version S: .lune 2015