HomeMy WebLinkAboutWPO201900062 Correspondence 2022-02-15 (2)ENGINEERING
HYDROLOGY AND HYDRAULIC CALCULATIONS BOOKLET FOR
SOUTHWOOD - PHASE 1
CLEAN EARTH FILL — NORTH AREA
TMP 90A1-1 D
ALBEMARLE COUNTY, VIRGINIA
DECEMBER 23, 2021
REVISED FEBRUARY 9, 2022
OWNER:
SOUTHWOOD CHARLOTTESVILLE, LLC
WILLIAM THIESSEN
609-651-6404
wthiessen(a)cvillehabitat.org
ENGINEER:
30 SCALE, LLC
MICHAEL MYERS, PE, CFM
434-242-2866
mike(W0scale.com
TABLE OF CONTENTS
STORMWATER MANAGEMENT/BMP NARRATIVE 3
LAND COVER CONDITIONS 5
STORM SEWER PIPE DESIGN AND INLET CALCULATIONS 6
SWM ACCESS ROAD DITCH DESIGN CALCULATIONS 9
OUTLET PROTECTION CALCULATIONS 12
NOAA ATLAS 14 PRECIPITATION VALUES 13
APPENDICES:
A.
ARMY CORPS APPROVAL LETTER (EMAIL)
17
B.
HYDRAFLOW REPORT - EXTENDED DETENTION POND
22
C.
VRRM SPREADSHEETS
49
D.
NUTRIENT CREDIT AVAILABILITY LETTER
59
E.
NRCS SOILS REPORT
61
STORMWATER MANAGEMENT NARRATIVE
PROJECT DESCRIPTION
THE PURPOSE OF THIS PROJECT IS TO PERFORM CLEAN EARTH FILL
OPERATIONS IN AN APPROXIMATE 1-ACRE GULLY LOCATED IN BETWEEN FIN
COURT AND IRIS COURT, BOUNDED ON THE SOUTH BY BITTERNUT LANE AND
ENDING AT THE WATER PROTECTION ORDINANCE BUFFER ON THE NORTH.
BASED ON SITE VISITS AND CORRESPONDENCE WITH THE US ARMY CORPS
OF ENGINEERS (ACOE), THE LIMITS OF DISTURBANCE COVERED BY THIS PLAN
IS OUTSIDE OF ANY PROTECTED ELEMENTS OF A "WATERS OF THE UNITED
STATES", AND THEREFORE NO ACOE PERMITTING OR REPORTING IS
REQUIRED. ALSO, NO DISTURBANCE OF THE WATER PROTECTION
ORDINANCE BUFFER IS PROPOSED AND THERE IS NO 100-YEAR FLOODPLAIN
WITHIN THE LIMITS OF DISTURBANCE.
FOLLOWING THE CLEAN EARTH FILL OPERATIONS, RUNOFF FROM THE FILL
AREA WILL FLOW OVERLAND TO THE EXTENDED DETENTION POND. THE
EXISTING RUNOFF FROM THE STORM SEWER ON BITTERNUT LANE WILL
CONTINUE TO FLOW VIA STORM SEWER PIPE, AND WILL BYPASS THE
EXTENDED DETENTION FACILITY AND OUTFALL INTO RIP -RAP OUTLET
PROTECTION BEFORE ENTERING THE WATER PROTECTION ORDINANCE
BUFFER.
CHANNEL PROTECTION
CHANNEL PROTECTION IS MET BY COMPLYING WITH 9VAC25-870-66(B)1b. THE
PEAK 1-YEAR, 24-HOUR DEVELOPED DISCHARGE RATE IS LESS THAN THE
MAXIMUM ALLOWABLE RUNOFF RATE FOR CONCENTRATED DISCHARGE
USING THE ENERGY BALANCE CRITERIA. REFER TO ENERGY BALANCE
SUMMARY ON THIS SHEET AND HYDRAULIC AND HYDROLOGIC
COMPUTATIONS BOOKLET FOR SUPPORTING CALCULATIONS.
Q1 MAXIMUM ALLOWABLE RUNOFF = 1.36 CFS
Q1 POST -DEVELOPED = 0.67 CFS OK
FLOOD PROTECTION
FLOOD PROTECTION IS MET BY COMPLIANCE WITH 9VAC25-870-66(C)2B. THE
PEAK 10-YEAR, 24-HOUR (10% AEP) COMBINED DEVELOPED DISCHARGE RATE
HAS BEEN REDUCED TO BE LESS THAN THE PRE -DEVELOPMENT 10-YEAR, 24-
HOUR DISCHARGE RATE FOR THE ENTIRE 6.28-ACRE DRAINAGE AREA TO THE
POINT OF ANALYSIS. THE FOLLOWING PEAK RATES ARE TAKEN FROM THE
Page 3 of 78
HYDRAFLOW CALCULATIONS REPORT LOCATED IN THE APPENDICES OF THIS
BOOKLET:
Q10 PRE -DEVELOPED = 25.5 CFS
Q10 POST DEVELOPED = 17.8 CFS OK
WATER QUALITY COMPLIANCE NARRATIVE
WATER QUALITY WILL BE MET BY THE EXTENDED DETENTION POND (LEVEL
ONE) AND THE PURCHASING OF NUTRIENT CREDITS. A LETTER OF
AVAILABILITY HAS BEEN PROVIDED ON SHEET 9 OF THE SITE PLAN FOR 0.43
LBS/YR OF SUPPLEMENTAL PHOSPHORUS REMOVAL. HOWEVER, THE
APPLICANT WILL ONLY NEED TO PURCHASE 0.11 LBS/YR TO COMPLY WITH
THE VRRM REQUIREMENTS.
THE NUTRIENT CREDITS WILL BE PURCHASED PRIOR TO WPO AMENDMENT
APPROVAL. THE EXTENDED DETENTION POND WILL BE PRIVATELY OWNED
AND MAINTAINED AND BE SUBJECT TO A STORMWATER MANAGEMENT
MAINTENANCE AGREEMENT.
NARRATIVE ON NUTRIENT CREDITS TO BE PURCHASED:
ON THE FIRST SUBMISSION OF THE VSMP PLAN, THE VRRM SPREADSHEET
HAD INCLUDED THE ENTIRE 2.33-ACRE DRAINAGE AREA AS THE SITE AREA.
ON THE 2ND SUBMISSION (2/9/2022), THE VRRM SPREADSHEET HAS BEEN
REVISED TO INCLUDE ONLY THE 1.01-ACRE DISTURBED AREA AS THE SITE
AREA. AS A RESULT, THE SUPPLEMENTAL NUTRIENT CREDITS TO BE
PURCHASED ARE 0.11 LBS/YEAR.
Page 4 of 78
LAND COVER CALCULATIONS
NOTE: HAZEL AND ELIOAK SOILS ARE NRCS " B" SOILS
PRE -DEVELOPMENT COMPOSITE CN CALCULATIONS
LAND COVER
(AC)
CN
CN*A COMPOSITE CN
ROADWAY/SIDEWALKS/DRIVEWAYS
0.26
98
ROOFTOP
0.25
98
GRAVEL TRAIL
0.03
98
TOTAL IMPERVIOUS
0.54
98
52.9
WOODS
1.58
55
86.9
LAWN
0.21
61
12.8
TOTAL AREA
2.33 AC
152.6 66
L (FT)
HI ELEV
LO ELEV
SLOPE
SHEET FLOW 100
489.5
481.5
8.0%
SHALLOW CONCENTRATED FLOW 89
481.5
472.0
10.7%
CHANNEL FLOW 658
472.0
431.0
6.2% TC = 7.2 MIN
POST -DEVELOPMENT COMPOSITE CN CALCULATIONS
LAND COVER
(AC)
CN
CN*A COMPOSITE CN
ROADWAY/SIDEWALKS/DRIVEWAYS
0.26
98
ROOFTOP
0.25
98
SWM ACCESS ROAD
0.09
98
TOTAL IMPERVIOUS
0.60
98
58.8
WOODS
0.60
55
33.0
LAWN
1.13
61
68.9
TOTAL AREA
2.33 AC
160.7 69
TIME OF CONCENTRATION GEOMETRY - POST -DEVELOPMENT
L (FT)
HI ELEV
LO ELEV
SLOPE
SHEET FLOW 100
489.5
481.5
8.0%
SHALLOW CONCENTRATED FLOW 89
481.5
472.0
10.7%
CHANNEL FLOW 642
472.0
431.0
6.4% TC = 7.2 MIN
NOTE: USE 5-MINUTE TIME OF CONCENTRATION FOR 2.33-ACRE DRAINAGE AREA FLOWING TO POND
OFFSITE COMPOSITE CN CALCULATIONS
LAND COVER
(AC)
CN
CN*A COMPOSITE CN
ROADWAY/SIDEWALKS/DRIVEWAYS
ROOFTOP
1.41
0.32
98
98
TOTAL IMPERVIOUS
WOODS
LAWN
1.73
2.16
0.06
98
55
61
169.5
118.8
3.7
TOTAL AREA
3.95 AC
292.0 74
Page 5 of 78
STORM SEWER DESIGN COMPUTATIONS (10-YEAR DESIGN STORM)
FROM TO A (INC) C AC (INC) Q (INC) AC (ACC) Q (ACC) DIA L INV UP INV DN S In Tc V2 Qcap
(AC) (AC) (CFS) (AC) (CFS) (IN) (FT) (FT) (FT) (%) (MIN) (FPS) (CFS)
5
4
3.16
0.55
1.74
11.47
1.74
11.47
36
31
460.71
459.32
4.00
0.013
7
8.7
133
4
3
0.79
0.70
0.55
3.65
2.29
15.12
36
255
459.22
435.91
9.00
0.013
7
11.5
200
3
2
0.00
2.29
15.12
36
47
435.81
433.26
5.00
0,013
7
11.5
149
2A
2
2.33
SEE SWM ROUTINGS
6.71 (SWM)
15
10
438.00
437.72
2.00
0.013
7
8.1
9
2
1
0.00
SEE SWM ROUTINGS
21.8 (SWM)
36
59
432.26
431.00
2.00
0.013
7
9.1
94
F2
F1
0.36
1 0.41
0.15
0.97
1 0.15
1 0.96
1 12
1 12
1 442.50
442.00
1 2.02
0.013
1 7
4.6
1 5
NOAA ATLAS 14 PRECIPITATION INTENSITIES: 2-YR = 5.02 INIHR, 10-YR = 6.61 INIHR
Inlet Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Friday, Feb 11 2022
STRUCTURE F2
Drop Grate Inlet
Calculations
Location
= Sag
Compute by:
Known Q
Curb Length (ft)
= -0-
Q (cfs)
= 0.98
Throat Height (in)
= -0-
Grate Area (sqft)
= 2.33
Highlighted
Grate Width (ft)
= 2.58
Q Total (cfs)
= 0.98
Grate Length (ft)
= 2.58
Q Capt (cfs)
= 0.98
Q Bypass (cfs)
= -0-
Gutter
Depth at Inlet (in)
= 1.20
Slope, Sw (ft/ft)
= 0.020
Efficiency (%)
= 100
Slope, Sx (ft/ft)
= 0.020
Gutter Spread (ft)
= 12.58
Local Depr (in)
= -0-
Gutter Vel (ft/s)
= -0-
Gutter Width (ft)
= 1.00
Bypass Spread (ft)
= -0-
Gutter Slope (%)
= -0-
Bypass Depth (in)
= -0-
Gutter n-value
= -0-
Page 7 of 78
Inlet Report
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc. Friday, Dec 24 2021
CURB INLETS 4 AND 5
Curb Inlet
Calculations
Location
= Sag
Compute by:
Q vs Depth
Curb Length (ft)
= 16.001(2) 8-FT THROATS
Max Depth (in)
= 6
Throat Height (in)
= 6.00
Grate Area (sqft)
_ -0-
Highlighted
Grate Width (ft)
_ -0-
Q Total (cfs)
= 10.50
Grate Length (ft)
_ -0-
Q Capt (cfs)
= 10.50
Q Bypass (cfs)
_ -0-
Gutter
Depth at Inlet (in)
= 5.98
Slope, Sw (ft/ft)
= 0.080
Efficiency (%)
= 100
Slope, Sx (ft/ft)
= 0.020
Gutter Spread (ft)
= 18.92
Local Depr (in)
_ -0-
Gutter Vel (ft/s)
_ -0-
Gutter Width (ft)
= 2.00
Bypass Spread (ft)
_ -0-
Gutter Slope (%)
_ -0-
Bypass Depth (in)
_ -0-
Gutter n-value
= -0-
.1 l—p—In 1r
NOTE: CURB INLETS 4 AND 5 WERE MODELED TOGETHER SINCE THEY ARE
EACH LOCATED IN A SUMP ON OPPOSITE SIDES OF BITTERNUT LANE.
COMBINED, THESE INLETS PROVIDE ADEQUATE CAPACITY TO CONVEY THE
2-YEAR DESIGN STORM WITHOUT OVERTOPPING THE CURB. THE ULTIMATE
DESIGN OF SOUTHWOOD PHASE 2 WILL HONOR THE LOCATIONS OF INLETS 4
AND 5; AND SUPPLEMENTAL STORM SEWER DESIGN AT THAT TIME WILL
REDUCE THE OVERLAND FLOWS ULTIMATELY FLOWING TO INLETS 4 AND 5.
Page 8 of 78
Channel Report
SWM ACCESS ROAD DITCH DESIGN
CALCULATIONS - LEFT SIDE
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.
DITCH CALCULATIONS - LEFT SIDE
Triangular
Side Slopes (z:1)
= 3.00, 3.00
Total Depth (ft)
= 1.00
Invert Elev (ft)
= 100.00
Slope (%)
= 15.00
N-Value
= 0.030
Calculations
Compute by:
Known Q
Known Q (cfs)
= 2.36
Elev (ft)
102.00 -
101.50
101.00
100.50
100.00
99.50
0 1 2 3
Section
4
Reach (ft)
Highlighted
Depth (ft)
Q (cfs)
Area(sgft)
Velocity (ft/s)
Wetted Perim (ft)
Crit Depth, Yc (ft)
Top Width (ft)
EGL (ft)
5 6 7
Thursday, Feb 10 2022
= 0.37
= 2.360
= 0.41
= 5.75
= 2.34
= 0.53
= 2.22
= 0.88
Depth (ft)
2.00
1.50
1.00
0.50
M
-0.50
8
Page 9 of 78
Channel Report SWM ACCESS ROAD DITCH DESIGN
p CALCULATIONS - RIGHT SIDE
Hydraflow Express Extension for Autodesk® Civil 3D® by Autodesk, Inc.
DITCH CALCULATIONS - RIGHT SIDE
Triangular
Side Slopes (z:1)
= 3.00, 3.00
Total Depth (ft)
= 0.50
Invert Elev (ft)
= 100.00
Slope (%)
= 15.00
N-Value
= 0.030
Calculations
Compute by:
Known Q
Known Q (cfs)
= 0.98
Elev (ft)
101.00 -
100.75
100.50
100.25
100.00
99.75
0 .5 1 1.5
Section
2
Reach (ft)
Highlighted
Depth (ft)
Q (cfs)
Area(sgft)
Velocity (ft/s)
Wetted Perim (ft)
Crit Depth, Yc (ft)
Top Width (ft)
EGL (ft)
Z5 3
Thursday, Feb 10 2022
= 0.27
= 0.980
= 0.22
= 4.48
= 1.71
= 0.37
= 1.62
= 0.58
Depth (ft)
1.00
0.75
0.50
0.25
Um
' -0.26
3.5 4
Page 10 of 78
M
rn
DESIGN OF OUTLET PROTECTION FROM A ROUND PIPE FLOWING FULL
MINIMUM TAILWATER CONDITION (Tw < 0.5 DIAMETER)
30
Outlet 2 Min. W = Do + La
Pipe I 7
Diameter, Do 1 I f� i
111 r•
La
T i w ter < 0.500 ► le, .. 01
of
4
I �i
li ilti j� :I
20
MIN L=14'
MIN 00=6"
Recommended Min.
dH=6•
3 5 10
010=19 CFS
Ii
50 3 1
Discharge, ft./Sec.
I
:1 mm�m>,nnwm>.elemmem
A.
ri
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4
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r~vV AI
I! 11 111
12/24/21, 8:53 AM Precipitation Frequency Data Server
NOAA Atlas 14, Volume 2, Version 3
Location name: Charlottesville,
Virginia, USA*
Latitude: 38.00080, Longitude: A
T-78.52350
Elevation: 455.13 ft**
" source: ESRI Maps
** source: USGS
POINT PRECIPITATION FREQUENCY ESTIMATES
G.M. Bonnin, D. Martin, B. Lin, T Parzybok, M.Yekta, and D.
Riley
NOAA, National Weather Service, Silver Spring, Maryland
PF tabular I PF graphical I Maps & aerials
PF tabular
PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches),
ae Intilmal rs000
Ouraean
D0000rege
1
2
5
10
25
o
50
d
100
300
500
1000
2
SmN
0.3107--0391
0.3]7-0465)
0.441-0.1544
0. 95-0.610
0.555-0885)
0.601-0]44
0.641-0798
0.678-0.1851
0.720-0.914
0.752-0968
137
10m1n
0.506-0624
0.604-0]p
0.707-0 ]1
0.792-0.976
0.88S1.09
0.95]-1.19
1.02-11.2
1.08-1.
1.144.45
1.19-1.52
15m1n
0.8320.780
(0.759-0.935)
(0.8£Wl.10)
1.00-1.24)
1.12438
1.21�50
1.29-1.60)
1.36-1]0
(1.43-1.82)
1.49-1.91
2.62
30anln
0.86]820]
1.05-829
1.27--1.5
1.45-?]9
1.68-2.0
1.8 228
1.97-2.48
2.11,285
2.28-2.90
A l-8.10
60m1n
1.08- .33
1.32-1.62
1.63-2.01
1.89-2.33
2.21A2.73
.47-3.
2.72-3.38
2.96-3.71
32 ]d 18
35 24..52
2Jrr
1.28-1.85
1.53199
1.92-2.49
2.25-2.92
2.88-3.48
3.00-3.93
3.35139
.89-4.88
4.153.58
45 3-8.14
SJrr
1.38-1.82
1.872..19
2.09-2.75
.44-3.21
2.90-3.82
.274.32
3.6H.85
4.02-5A0
4.52815
4.9441.80
Bfir
1:9-229
.15-2.78
2.67-3A2
.134.03
3.73-4.83
4.25-5.53
4:8-0.2
5.32-]
6.08-8.20
8.72-920
2.55
3.07
&83
45
51
6].
3
8
89
11.33
229
2]1-35
3.384.38
3.9]531
4]8
,12-hr
8
029
Q.A
8.13-11.2
9.11-12.8)
69
4.72
68
686
7.96
125
10.2L-hr
233403542
3.331.
23528t.416.08-7.
1-8,8
9.07-11.8
10.8-13.8
11.9-15.
3.59
5.5
6.52
T.94
912
8
..
139
&8
2-day
(323-i)
(4.96-69
(5.82-727)
(7.038.83)
(
0
(10.2-13.1)
(11.9-15.5)
(132-17.41)
3.83
(348-129)
4.84
(421-5.13)
5.69
(5.34-652)
6.93
(6.26-]65)
8A3
(7.57-9.29)
9.66
(8.64-103)
11.0
(9]8-122)
12.5
(11.0-13.8)
14.7
(12]-162)
16.5
(14.1-18.3)
d O6
0.92
6.25
T.33
8.91
10.2
11.]
132
15.5
17.4
(373-14
(4.51i.40)
(5]2-685)
(6.]0-803)
(8.11-9.75)
(925-112)
(10.5-128)
(11.8-14.5)
(136-1]0)
(15.1-19.1)
492
5.6a
7.10
826
9.94
11.3
f2.8
1M
16.8
18.7
Tylay
(4 m 6 13)
1 (523-a 18) IL(6
52-] ]2)
1 (7 58-8 99) JI
(9.06-10.8)
(10 3-12 3) 11
(11 5-13.9)
1 (12.9-15.7)
(14 8-18 3)
(16 3-20 5)
5.34
BA1
].92
9.14
16.9
12.3
13.8
15.3
17.6
19.4
10-0ay
(494-5 ]])
(5.94-0.93)
(732-855)
(8.43-986)
(9.98-11.7)
(112-132)
(12.5-14.9)
(13.8-16.6)
(157-191)
(172.211)
].02
8.3]
10.1
11.5
13.3
14.8
18.3
I7-a
19.9
21.5
(658-750)
(7.85-8.95)
(947-tf18)
n: 123)
(12.4-14.2)
(137-15.8)
(15.1-174)
(16.419.1)
(182-214)
(195-232)
8.61
10.2
12.1
13.5
15.J
16.8
18.1
19.5
ii li
22.6
30-0ay
(811-916)
1 (9.82-10.9) 11
(114-12.8) 11
(12 -143)
1 (14.4-16.3) 11
(157-17.8) 11
(16.9-193)
(18.1-20.8)
(19.7-223)
(208-242)
10.7
12.]
14.6
16.4
1&5
20.0
21.5
229
24.T
26.1
(102-114) 11
(12.0-13.4) 11
(14 o-15]) 11
(155-174)
1 (17.4-19.8) 11
(18.8-21.2) 11
(20.2-228)
(21.424.3)
(23.0-26.3)
(242-278)
12.6
14.a
V.1
16.6
21.0
23.8
22
2i
2T.5
28.6
60-0ay
(12 o-133)
(14.1-15.8)
(162-181)
(178-199)
(19.9-222)
(21.3-23.9)
(22]-255)
(24.1-2].1)
(25.]-29.1)
(269-308)
1 Precipitation frequency (PF) estimates in Nis table am based on frequency analysis of partial duration series (PDS).
Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that predpftation frequency estimates (far
a given duration and average recunence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not
Necked against probable maximum precipitation (PMP) estimates and may be higher than wnently valid PMP values.
Please later to NOAA Ntas 14 dommer8 for more infmmation.
Backto Top
PF graphical
Page 13 of 78
hftps://hdsc.rws.noaa.govlhdsc/pfds/pfds_printpage.html?lat=38.0008&Ion=-78.5235&data=depth&units=english&series=pds 1/3
12/24/21, 8:53 AM Precipitation Frequency Data Server
PDS-based depth -duration -frequency (DDF) curves
Latitude: 38.0008'. Longitude:-78.5235'
30
5
_ C C
E
C
C
ry L L
N N R
T N
N N NR
b
Vf
1O
N M Ora
Duration
Average recurrence interval (years)
WAA Adas 14, W lu. 2. Version 3 Created WWI: M Dec 2413:53:06 2021
Back to Top
Maps & aerials
Small scale terrain
Large scale terrain
r
Washington, D.C.' -i,i
Harti.onb�rwun[on 'WI
VIRG,INIA
IA '
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— 1D
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— 44ay
— 30 e
— ?AW
— 6D
— 10-d2y
— 2Ar
— 2Ddry
— 3-Ar
— 3Ddq
— enr
— 4saay
— 2L
Page 14 of 78
hftps://hdsc.rws.noaa.gov/hdsctpfds/pfds_Printpage.html?lat=38.0008&Ion=-78.5235&data=depth&units=english&series=pds 213
12/24/21, 8:53 AM
Precipitation Frequency Data Server
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60mi
Backto Top
US Denarb M of commerce
National Oceanic arM Atmosphenc Mministration
Natlmul Weather Se. i
National Water Center
1325 East West Highway
Silver Spnng, MD 20910
Questions?: HDSC Q caUaaariannaa gpy
Disdaimer
Page 15 of 78
hffps://hdsc.rws.noaa.govlhdsctpfds/pfds_printpage.html?lat=38.0008&Ion=-78.5235&data=depth&units=english&series=pds 313
12/24/21, 8:53 AM Precipitation Frequency Data Server
NOAA Atlas 14, Volume 2, Version 3
Location name: Charlottesville,
Virginia, USA*
Latitude: 38.00080, Longitude: A
T-78.52350
Elevation: 455.13 ft**
" source: ESRI Maps
** source: USGS
POINT PRECIPITATION FREQUENCY ESTIMATES
G.M. Bonnin, D. Martin, B. Lin, T Parzybok, M.Yekta, and D.
Riley
NOAA, National Weather Service, Silver Spring, Maryland
PF tabular I PF graphical I Maps & aerials
PF tabular
PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches/houw
Average recurrence Interval (years)
2
5
10
11 25
50
100
200
500
1000
i°
3.80-4.89
4.52-5.58
5.29-6.53)
5.94-7.32
6.66-8.22
.21-8 93
7.W-9.58
(8.102)
8.64 11.0
9.02- 1.6)
10m1n
3.W3.]4
3.624.46
4.24-5.23
4: 5-5.86
5: 1-0.55
5: 4 11
6.11-7.81
6.45-809
6.83-8.68
.18-9.14
15m1n
2.53-3.12
(3.04-3.74)
1 (3.58-4.40)
4.0141..94)
1 t4.48-5.54)4.84800
5.15-6.42)
5.43-0.80
(5: 3-].28)
5.95-7.65
F30�l°
1.73-2.14
2.10-2.58
2.5h3.1
2.90-3.58
3.324.10
3.65-4.52
3.954.91
4.2-530
4.56-5.79
4.824120
60m1n
1.08- .33
1.32-1.62
1.63-2.01
1.89-2.33
2.21A2.73
.47-3.08
2]2338
2.96-3.71
32 ]d 18
3: 2°-4..52
2Jrr
0.632 824
0.766-0.998
0.958-°1.24
1.13-1.48
1.33-1.73
1.50-398
1.67-r�2.20
1.85-2.44
208-2.78
2.28-3.07
SJrr
0.460-0.605
0.556-0.731
0.694-0915
0.813-1.07)
0.984-1
1.09-1.4/
1.21A1.61
1.34-1.80
1.51-2.05
1.64-2.28
6fir
0.299-0.382
0.360-0.481
0.445-0.5
0.5 2-0673
0.624-080
0.710-0.923
0. 9]7--1..0
0.889-1.18
1.02-u1.3
1.125854
12-1r
0.186-0242
0225-0292
0.2]9-0.383
0.330-0429
0.398-0.520
0.4500.602
0.51]-0.690
0.582-0.98
0.675-0..931
0: 56-1.06)
24hr
0.114-0.142
0.138-0 72
0.176-0.220
02W-0259
0.253-0.318
0.292-0.1388
0.333-0423
0.378-0.480
0.443-0.1578
0.4%-0655
0.075 7F
0.09,gFog
7F
0.,38
0.,86
0.,90
0.21]
0.248
0.259
0.325
(0.067-0.084)
(0.081-0.101)
(0.103 0.129)
(0.121-0.151)
0.147-0.184)
(0.167-0.211)
(0.189-0.241)
(0.213-0274)
(0.247-0.32)
(0.274-0.362)
0.051
0.084
0.082
0.096
0 7
0.136
0.153
0.,74
0.206
0.229
(0048-0059)
(0.059-0.071)
(O.D74-0091)
(0.08]-0106)
(0.105-0.129)
(0120-0148)
(0.136-0169)
(0.1530.192)
(0.1]]-025)
(0.196-0254)
0.0427F
0.051
0.065
0.116 7F
0.093
0.107
0.121
0.1 88
0.161
0.181
(0.039-0046)
(0.04]-0.056)
(0.060-00]i)
(0.0]0-0084)
(0.084-0.102)
(0.096-0117)
0.109-0133)
(0.123-0.151)
(0.142-0177)
(0.157 0199)
0028
0.034
0.042
0.049
0.059
0.0671F0.0]6
0.088
0.100
0.111
7�
(0.02E)031)
(0.031-0.037)
(0039-0048).045-
(00053)
(0.054-0.064)
(2061-0073)
08
0.059-03)
(0.077-0.094)
(0.088-0109)
(0097-0122)
0.02
0.033
0.038
0.015
0.051
0.057
0.080
0.073
0.081
F,;�W�O02
10-0�
(0.021-0024)
(0.025-0.029)
(0.D31. 0036)
(020 0041)
(0.042-0.049)
(0.04]-0.055)
0.052-0.052)
(0.058-0.069)
(0065-0079)
(0.0]2-0.088)
0.015
0.017
0.021
0.024
0.028
0.031
0.034
_. ..
0.037
.._
0.041
0.045
20-0ay
(0014-0016)
(0.018-0.019)
(0.020-0023)
(0.022-0028)
(0.026-0.030)
(2029-0033)
0.031-0.038)
(0.03441.040)
(0.038-0045)
(0.041-0.048)
A,011-0.013)
0.012
0.014
0.01]
0.019
002023
0.025
0.021
o.oao
0.031
(0.FX30-0ay
(0.013-0.015)
(0016-0.018)
(0.018-0.020)
(0.0200.023)
(0022-0025)
0.023-0.027)
(0.025-0.029 )
(0.027-0.032)
( 0.029-0.034)
0.0,o
0.012
0.014
T 0.015
0.ow
0.019
0.020
002/
0.023
&CEI
(0.009-0.011)
(0.011-0.012)
(0.013-0.015)
(0.014-0.016)
(0.016-0.018)
(0017-0020)
0.019-0.021)
(0.0200.023)
(0.021-0.024)
(0.022-0.026)
0.009
0.010
0.012
0.013
0.0,5
0.016
0.01]
0.0,8
0.0,9
0.020
80-0ay
(0.008-0.009)
(0.010-0.011)
(0.011-0.013)
(0.012-0.014)
(0.014-0.015)
(0015-0017)
0.016-0.018)
(0.017-0.019)
(Lol".020)
(0.019-0.021)
1 Precipitation 0equency (PF) estimates in Mis table am based on frequency analysis of partial duration series (PDS).
Numbers in parenthesis are PF estimates at Inver and upper bountls of the 90% mnfidenm interval. The probability that precipitation frequency estimates (for
a given duration and average recurrence interval) will be greater than the upper bound (or less Man the lower bound) is 5%. Estimates at upper bounds are not
Necked against probable maximum precipitation (PMP) estimates and may be higher Man mmently valid PMP values.
Please refer to NOAA Atlas 14 domment far more information.
Backto Top
PF graphical
Page 16 of 78
https://hdsc.rws.noaa.govlhdsc/pfds/pfds_printpage.html?lat=38.0008&Ion=-78.5235&data=intensity&units=english&series=pds 1/3
APPENDIX A
ARMY CORPS APPROVAL LETTER (EMAIL)
APPENDIX B
HYDRAFLOW REPORT FOR EXTENDED
DETENTION POND
APPENDIX C
APPENDIX D
NUTRIENT CREDIT AVAILABILITY LLETTER
APPENDIX E
NRCS SOILS REPORT
Page 17 of 78
Mike Myers
From:
Pero, Vincent D CIV USARMY CENAO (USA) <Vincent.D.Pero@usace.army.mil>
Sent:
Wednesday, December 8, 2021 6:33 AM
To:
Mike Myers; William Thiessen; RJ Wright
Cc:
Frank Pohl; Andrew Vinisky, Bryan Rieckmann
Subject
RE: Southwood - Proposed Fill in Northern Gully
HI Mike
Thanks for showing me around the site. No permit is required from my office to fill the northern gully. The Corps
determination for that area only is that it is a drainage channel and not a water of the U.S.
Thanks and let me know if you need anything more from my office at this time
Vinny
Vinny Pero
U.S. Army Corps of Engineers
Norfolk District
Western Virginia Regulatory Section
Charlottesville Field Office
920 Gardens Boulevard, Suite 103-B
Charlottesville, Virginia 22901
757-297-0011 (temp while teleworking)
The Norfolk District is committed to providing the highest level of support to the public. In order for us to better serve
you, please complete our Customer Satisfaction Survey at:
https:Hregulatory.ops.usace.army.mil/ords/f?p=136:4
From: Mike Myers <mike@30scale.com>
Sent: Thursday, December 2, 20217:22 PM
To: Pero, Vincent D CIV USARMY CENAO (USA)<Vincent.D.Pero@usace.army.mil>; William Thiessen
<wthiessen@cvillehabitat.org>; RJ Wright<rjwright@faulconerconstruction.com>
Cc: Frank Pohl <fpohl@albemarle.org>; Andrew Vinisky <avinisky@cvillehabitat.org>; Bryan Rieckmann
<brieckma nn @faulconerconstruction.com>
Subject: [Non-DoD Source] Southwood - Proposed Fill in Northern Gully
Vinny, Thanks for meeting up with Bill (Habitat for Humanity), RJ Wright (Faulconer Construction) and
me this morning at Southwood to walk the site and discuss our plan to fill the northern gully with
excess dirt from Village 1 in an effort to reduce costs for trucking off excess dirt. Based on our site
meeting this morning, it is our understanding that the proposed fill operations will not require a Corps
permit. However, I wanted to make sure you had the various maps so that you could provide
Albemarle County and us written confirmation.
Page 18 of 78
Our goal is to perform the fill operations in 1 Q of 2022 so that we can coordinate with the Village 1
construction schedule. I have provided snapshots of the various maps below and here is a L LINK
to the full-size pdfs of each of these.
Thanks very much, and please let me know if you have any questions or if you need clarification on
anything, great to see you this morning, Mike
PS to Frank and Matt, Once we hear back from Vinny, we would like to schedule a meeting with you
(onsite preferably) so we can review our proposal in the field prior to formal submission of the E&S
Plan. I will follow up with you, but wanted you to be aware of our plans and schedule. Feel free to
reach out with questions as well, Mike
Michael Myers, PE, CFM 30 Scale, LLC C: 434-242-2866 1 Web: 30Scale.com
MAPS/EXHIBITS/PHOTOS
Marked -Up WSSI WOTUS MAP — NORTHERN GULLY
TEna 1)am was1
(199T ManwR a .u.R
OMroenm ManvN Eesi
6 TEe RwA O -Sa. I
I Fq work was pe
STREAM REACH
NORTHERN STUDY
8 TNn WOTUS9e_am
AREA BOUNDARY
9 NWSSI'.opmpn. IN.
NA1 cw+h .. wsler
tw man
d4C ao*aO
Ctesle Com
1�
CFR S
cpas.c6m,1a �o
2t ,pft
O •7• M
Evan."w l.rtwa.
05
S.i
bac0E 10W awn
D2
wooWb .RrWM 9'
--- ---J
C6 [t2�
NORTHERN
10. Svaam�bco m,
oapa�lMp ywo
�'
GULLY TO BEv
.ems�Mu.
E1
Thaw n.a awe..
FILLED
C'2 E6 (NOTEM
11. Tno Earma'Epfemm.
Eaw. W55p. 6a18 a0
/
01
rol v fm by ft COE, I
a mn M,naa6on rapMw
f
F
Marked -up Albemarle County GIS Map showing approximate location of fill, storm sewer and
E&S
2
Page 19 of 78
Conceptual Fill Plan
s...I
.�onc�a
wowwc�
ort�
3
Page 20 of 78
Photo of "Ski Slope" in Village 1 — Excess dirt to be placed in northern gully
"ski slope"
Excess dirt from
Village 1 to be
placed in northern
gully
�� ��� 1.�� ice`...= 1"`�.�►-+sc �,+t �r � •-ram . - ' t '
Li
�AIP
•.
4
Page 21 of 78
APPENDIX A
ARMY CORPS APPROVAL LETTER (EMAIL)
APPENDIX B
HYDRAFLOW REPORT FOR EXTENDED
DETENTION POND
APPENDIX C
VRRM SPREADSHEETS
APPENDIX D
NUTRIENT CREDIT AVAILABILITY LLETTER
APPENDIX E
NRCS SOILS REPORT
Page 22 of 78
Watershed Model Schematic
I
Hydragow Hydrographs Extension for AutodeskO Civil 3136 by Autodesk, Inc. v2022
11
Leaend
tYd. Origin Description
1 SCS Runoff PRE -DEVELOPMENT
2 SCS Runoff POST -DEVELOPMENT
4 SCS Runoff PRE-DEV POND
5 SCS Runoff POST-DEV TO POND
7 Reservoir ROUTING
9 SCS Runoff OFFSITE
11 Combine COMBINED OUTFLOW
Project: NG SWM ROUTINGS.gpw Friday, 02 / 1 f#2=f 78
Hydraflow Table of Contents
NG SWM ROUTINGS.gpw
Hydraflow Hydrographs Extension for Autodesk® Civil 3DO by Autodesk, Inc. v2022
Friday, 02 / 1112022
Watershed Model Schematic...................................................................................... 1
1 -Year
HydrographReports...................................................................................................................
Hydrograph No. 1, SCS Runoff, PRE-DEVELOPMENT..........................................................
TR-55 Tc Worksheet...........................................................................................................
Hydrograph No.
Hydrograph No.
Hydrograph No.
Hydrograph No.
Pond Report
Hydrograph No.
Hydrograph No.
10 - Year
2, SCS Runoff, POST-DEVELOPMENT......................................................
4, SCS Runoff, PRE-DEV POND.................................................................
2
2
3
4
5
5, SCS Runoff, POST-DEV TO POND...........................................................
6
7, Reservoir, ROUTING.................................................................................
7
- POND...........................................................................................................
8
9, SCS Runoff, OFFSITE...............................................................................
9
11, Combine, COMBINED OUTFLOW.......................................................
10
HydrographReports.................................................................................................................
11
Hydrograph No.
1, SCS Runoff, PRE-DEVELOPMENT........................................................
11
Hydrograph No.
2, SCS Runoff, POST-DEVELOPMENT......................................................
12
Hydrograph No.
4, SCS Runoff, PRE-DEV POND.................................................................
13
Hydrograph No.
5, SCS Runoff, POST-DEV TO POND .........................................................
14
Hydrograph No.
7, Reservoir, ROUTING...............................................................................
15
Hydrograph No.
9, SCS Runoff, OFFSITE.............................................................................
16
Hydrograph No.
11, Combine, COMBINED OUTFLOW.......................................................
17
100 - Year
HydrographReports.................................................................................................................
18
Hydrograph No.
1, SCS Runoff, PRE-DEVELOPMENT........................................................
18
Hydrograph No.
2, SCS Runoff, POST-DEVELOPMENT......................................................
19
Hydrograph No.
4, SCS Runoff, PRE-DEV POND.................................................................
20
Hydrograph No.
5, SCS Runoff, POST-DEV TO POND .........................................................
21
Hydrograph No.
7, Reservoir, ROUTING...............................................................................
22
Hydrograph No.
9, SCS Runoff, OFFSITE.............................................................................
23
Hydrograph No.
11, Combine, COMBINED OUTFLOW.......................................................
24
IDFReport.................................................................................................................. 25
Page 24 of 78
Hydrograph Report
2
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Hyd. No. 1
PRE -DEVELOPMENT
Hydrograph type
= SCS Runoff
Storm frequency
= 1 yrs
Time interval
= 2 min
Drainage area
= 6.280 ac
Basin Slope
= 0.0 %
Tc method
= TR55
Total precip.
= 3.05 in
Storm duration
= 24 hrs
Composite (Area/CN) _ [(3.950 x 74) + (2.330 x 66)] / 6.280
Q (cfs)
8.00
.Im
4.00
2.00
0.00 -t
0 120 240
Hyd No. 1
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
PRE -DEVELOPMENT
Hyd. No. 1 -- 1 Year
360 480 600 720 840
Friday, 02 / 1112022
= 7.554 cfs
= 720 min
= 17,994 cuft
= 71"
= Oft
= 7.20 min
= Type II
= 484
Q (cfs)
8.00
4.00
2.00
960 1080 1200 1320 1440 1560
Time (min)
Page 25 of 78
3
TR55 Tc Worksheet
Hydraflow Hydrographs Extension for AutodeskO Civil 3DO by Autodesk, Inc. v2022
Hyd. No. 1
PRE -DEVELOPMENT
Description
A
B
C
Totals
Sheet Flow
Manning's n-value
= 0.150
0.011
0.011
Flow length (ft)
= 100.0
0.0
0.0
Two-year 24-hr precip. (in)
= 3.36
0.00
0.00
Land slope (%)
= 8.00
0.00
0.00
Travel Time (min)
= 5.49 +
0.00 +
0.00 =
5.49
Shallow Concentrated Flow
Flow length (ft)
= 89.00
0.00
0.00
Watercourse slope (%)
= 3.30
0.00
0.00
Surface description
= Unpaved
Paved
Paved
Average velocity (ft/s)
=2.93
0.00
0.00
Travel Time (min)
= 0.51 +
0.00 +
0.00 =
0.51
Channel Flow
X sectional flow area (sqft)
= 1.00
0.00
0.00
Wetted perimeter (ft)
= 2.00
0.00
0.00
Channel slope (%)
= 6.20
0.00
0.00
Manning's n-value
= 0.025
0.015
0.015
Velocity (ft/s)
=9.33
0.00
0.00
Flow length (ft)
((0))658.0
0.0
0.0
Travel Time (min)
= 1.18 +
0.00 +
0.00 =
1.18
Total Travel Time, Tc..............................................................................
7.20 min
Page 26 of 78
Hydrograph Report
4
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Hyd. No. 2
POST -DEVELOPMENT
Hydrograph type
= SCS Runoff
Storm frequency
= 1 yrs
Time interval
= 2 min
Drainage area
= 6.280 ac
Basin Slope
= 0.0 %
Tc method
= User
Total precip.
= 3.05 in
Storm duration
= 24 hrs
Composite (Area/CN) _ [(3.950 x 74) + (2.330 x 69)] / 6.280
Q (cfs)
10.00
MA
. m
4.00
gut
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
POST -DEVELOPMENT
Hyd. No. 2 -- 1 Year
Friday, 02 / 1112022
= 8.098 cfs
= 720 min
= 19,103 cuft
= 72"
= Oft
= 7.20 min
= Type II
= 484
Q (cfs)
10.00
�
4-00
2.00
0.00 1 1 1 1 10.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 2 Time (min)
Page 27 of 78
Hydrograph Report
5
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Hyd. No. 4
PRE-DEV POND
Hydrograph type
= SCS Runoff
Storm frequency
= 1 yrs
Time interval
= 2 min
Drainage area
= 2.330 ac
Basin Slope
= 0.0 %
Tc method
= User
Total precip.
= 3.05 in
Storm duration
= 24 hrs
Q (cfs)
2.00
1.00
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
PRE-DEV POND
Hyd. No. 4 -- 1 Year
120 240 360 480 600 720 840 960
Hyd No. 4
Friday, 02 / 1112022
= 1.853 cfs
= 720 min
= 4,811 cult
= 66
= Oft
= 7.20 min
= Type II
= 484
Q (cfs)
2.00
1.00
' 0.00
1080 1200 1320 1440 1560
Time (min)
Page 28 of 78
I
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Friday, 02 / 1112022
Hyd. No. 5
POST-DEV TO POND
Hydrograph type
= SCS Runoff
Peak discharge
= 2.412 cfs
Storm frequency
= 1 yrs
Time to peak
= 720 min
Time interval
= 2 min
Hyd. volume
= 5,892 cuft
Drainage area
= 2.330 ac
Curve number
= 69
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 7.20 min
Total precip.
= 3.05 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Q (Cfs)
3.00
2.00
1.00
0.00
0 120 240
Hyd No. 5
POST-DEV TO POND
Hyd. No. 5 -- 1 Year
360 480 600 720 840 960
Q (cfs)
3.00
2.00
1.00
0.00
1080 1200 1320 1440 1560
Time (min)
Page 29 of 78
Hydrograph
Report
7
HydraBow Hydrographs Extension for Autodesk® Civil 3138 by Autodesk, Inc. v2022
Friday, 02 / 11 / 2022
Hyd. No. 7
ROUTING
Hydrograph type
= Reservoir
Peak discharge
= 0.670 cfs
Storm frequency
= 1 yrs
Time to peak
= 730 min
Time interval
= 2 min
Hyd. volume
= 5,892 cuft
Inflow hyd. No.
= 5 - POST-DEV TO POND
Max. Elevation
= 440.84 ft
Reservoir name
= POND
Max. Storage
= 1,323 cuft
Storage Indication method used
Q (cfs)
3.00
tf
1.00
0.00
0 120 240
Hyd No. 7
360 480 600
— Hyd No. 5
ROUTING
Hyd. No. 7— 1 Year
720
Q (cfs)
3.00
2.00
1.00
0.00
840 960 1080 1200 1320 1440 1560
® Total storage used = 1,323 cult Time (min)
Page 30 of 78
Pond Report $
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Friday, 02 / 1112022
Pond No. 3 - POND
Pond Data
Contours -User-defined contour areas.
Conic method used for volume calculation. Begining
Elevation = 438.00 ft
Stage / Storage Table
Stage (ft) Elevation (ft)
Contour area (sqft)
Incr. Storage (cuft)
Total storage (cuft)
0.00 438.00
55
0
0
2.00 440.00
537
509
509
4.00 442.00
1,488
1,946
2,455
6.00 444.00
2,884
4,295
6,750
7.00 445.00
3,617
3,243
9,993
Culvert / Orifice Structures
Weir Structures
[A]
[B]
[C]
[PrfRsr]
[A]
[B]
[C]
[D]
Rise (in)
= 36.00
4.00
0.00
0.00
Crest Len (ft)
= 12.57
2.00
Inactive
0.00
Span (in)
= 36.00
4.00
0.00
0.00
Crest El. (ft)
= 444.00
442.00
0.00
0.00
No. Barrels
= 1
1
0
0
Weir Coeff.
= 3.33
3.33
3.33
3.33
Invert El. (ft)
= 438.00
438.00
0.00
0.00
Weir Type
= 1
Red
Red
-
Length (ft)
= 40.00
1.00
0.00
0.00
Multi -Stage
= Yes
No
No
No
Slope (%)
= 1.00
1.00
0.00
n/a
N-Value
= .013
.013
.013
n/a
Orifice Coeff.
= 0.60
0.60
0.60
0.60
Exfil.(in/hr)
= 0.000 (by
Wet area)
Multi -Stage
= nits
Yes
No
No
TW Elev. (ft)
= 0.00
Stage (ft)
8.00
6.00
4.00
2.00
0.00
0.00 8.00
Total O
Note: Culven/Onfice outflow are analyzed under inlet (ic) and outlet (oc) watrol. Weir risers checked for orifice conditions (ic) and submergence (a).
Stage / Discharge
16.00 24.00 32.00 40.00 48.00 56.00 64.00 72.00
Elev (ft)
446.00
.r.. Kille
442.00
440.00
1 438.00
80.00
Discharge (cfs)
Page 31 of 78
Hydrograph Report
9
Hydraflow Hydrographs Extension for Autodesk® civil 3138 by Autodesk, Inc. v2022
Hyd. No. 9
OFFSITE
Hydrograph type
= SCS Runoff
Storm frequency
= 1 yrs
Time interval
= 2 min
Drainage area
= 3.950 ac
Basin Slope
= 0.0 %
Tc method
= User
Total precip.
= 3.05 in
Storm duration
= 24 hrs
Q (cfs)
6.00
5.00
4.00
3.00
2.00
1.00
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
OFFSITE
Hyd. No. 9 -- 1 Year
Friday, 02 / 11 / 2022
= 5.797 cfs
= 720 min
= 13,480 cult
= 74
= Oft
= 8.30 min
= Type II
= 484
Q (cfs)
6.00
5.00
4-00
3.00
2.00
1.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 9 Time (min)
Page 32 of 78
10
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3138 by Autodesk, Inc. v2022
Friday, 02 / 11 / 2022
Hyd. No. 11
COMBINED OUTFLOW
Hydrograph type
= Combine
Peak discharge
= 5.797 cfs
Storm frequency
= 1 yrs
Time to peak
= 720 min
Time interval
= 2 min
Hyd. volume
= 13,480 cuft
Inflow hyds.
= 9
Contrib. drain. area
= 3.950 ac
Q (cfs)
6.00
5.00
4.00
3.00
2.00
1.00
0.00 -L
0
COMBINED OUTFLOW
Hyd. No. 11 -- 1 Year
Q (cfs)
6.00
5.00
4-00
3.00
2.00
1.00
' ' 0.00
120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 11 —Hyd No. 9 Time (min)
Page 33 of 78
Hydrograph Report
11
HydraBow Hydrographs Extension for Autodesk® Civil 3138 by Autodesk, Inc. v2022
Hyd. No. 1
PRE -DEVELOPMENT
Hydrograph type
= SCS Runoff
Storm frequency
= 10 yrs
Time interval
= 2 min
Drainage area
= 6.280 ac
Basin Slope
= 0.0 %
Tc method
= TR55
Total precip.
= 5.58 in
Storm duration
= 24 hrs
* Composite (Area/CN) = [(3.950 x 74) + (2.330 x 66)] / 6.280
Q (cfs)
28.00
24.00
20.00
16.00
:m
4.00
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
PRE -DEVELOPMENT
Hyd. No. 1 -- 10 Year
Friday, 02 / 11 / 2022
= 25.51 cfs
= 720 min
= 58,455 cuft
= 71*
= Oft
= 7.20 min
= Type II
= 484
Q (cfs)
28.00
24.00
20.00
16.00
12.00
4.00
I I I I I I , 0.00
120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
- Hyd No. 1 Time (min)
Page 34 of 78
Hydrograph Report
12
HydraBow Hydrographs Extension for Autodesk® Civil 3138 by Autodesk, Inc. v2022
Hyd. No. 2
POST -DEVELOPMENT
Hydrograph type
= SCS Runoff
Storm frequency
= 10 yrs
Time interval
= 2 min
Drainage area
= 6.280 ac
Basin Slope
= 0.0 %
Tc method
= User
Total precip.
= 5.58 in
Storm duration
= 24 hrs
* Composite (Area/CN) = [(3.950 x 74) + (2.330 x 69)] / 6.280
Q (cfs)
28.00
24.00
20.00
16.00
:m
4.00
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
POST -DEVELOPMENT
Hyd. No. 2 -- 10 Year
Friday, 02 / 11 / 2022
= 26.42 cfs
= 718 min
= 60,489 cult
= 72*
= Oft
= 7.20 min
= Type II
= 484
Q (cfs)
28.00
24.00
20.00
16.00
12.00
4.00
0.00 ' - ' ' 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 2 Time (min)
Page 35 of 78
13
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Friday, 02 / 1112022
Hyd. No. 4
PRE-DEV POND
Hydrograph type
= SCS Runoff
Peak discharge
= 7.873 cfs
Storm frequency
= 10 yrs
Time to peak
= 720 min
Time interval
= 2 min
Hyd. volume
= 18,047 cuft
Drainage area
= 2.330 ac
Curve number
= 66
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 7.20 min
Total precip.
= 5.58 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Q (Cfs)
8.00
. 19
4.00
2.00
PRE-DEV POND
Hyd. No. 4 -- 10 Year
Q (cfs)
8.00
. 11
4.00
2.00
0.00 t I I I I' ' ' 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 4 Time (min)
Page 36 of 78
Hydrograph Report
14
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Hyd. No. 5
POST-DEV TO POND
Hydrograph type
= SCS Runoff
Storm frequency
= 10 yrs
Time interval
= 2 min
Drainage area
= 2.330 ac
Basin Slope
= 0.0 %
Tc method
= User
Total precip.
= 5.58 in
Storm duration
= 24 hrs
Q (cfs
10.00
M1
. ��
4.00
M M
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
POST-DEV TO POND
Hyd. No. 5 -- 10 Year
Friday, 02 / 1112022
= 8.828 cfs
= 720 min
= 20,205 cuft
= 69
= Oft
= 7.20 min
= Type II
= 484
Q (cfs)
10.00
KI
M
4-00
2.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 5 Time (min)
Page 37 of 78
Hydrograph Report
15
HydraBow Hydrographs Extension for Autodesk® Civil 3138 by Autodesk, Inc. v2022
Hyd. No. 7
ROUTING
Hydrograph type
= Reservoir
Peak discharge
Storm frequency
= 10 yrs
Time to peak
Time interval
= 2 min
Hyd. volume
Inflow hyd. No.
= 5 - POST-DEV TO POND
Max. Elevation
Reservoir name
= POND
Max. Storage
Storage Indication method used.
Q (cfs)
10.00
.M
4.00
ROUTING
Hyd. No. 7 — 10 Year
Friday, 02 / 11 / 2022
= 6.710 cfs
= 724 min
= 20,204 cuft
= 442.91 ft
= 4,410 cuft
Q (Cfs)
10.00
4-00
2.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
— Hyd No. 7 —Hyd No. 5 ®Total storage used = 4,410 cult Time (min)
Page 38 of 78
Hydrograph Report
16
Hydraflow Hydrographs Extension for Autodesk® civil 3138 by Autodesk, Inc. v2022
Hyd. No. 9
OFFSITE
Hydrograph type
= SCS Runoff
Storm frequency
= 10 yrs
Time interval
= 2 min
Drainage area
= 3.950 ac
Basin Slope
= 0.0 %
Tc method
= User
Total precip.
= 5.58 in
Storm duration
= 24 hrs
Q (cfs)
18.00
15.00
12.00
• m
.m
3.00
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
OFFSITE
Hyd. No. 9 -- 10 Year
Friday, 02 / 11 / 2022
= 17.77 cfs
= 718 min
= 40,650 cuft
= 74
= Oft
= 8.30 min
= Type II
= 484
Q (cfs)
18.00
15.00
12.00
lllll• tt
M
3.00
0.00 ' 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 9 Time (min)
Page 39 of 78
17
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3138 by Autodesk, Inc. v2022
Friday, 02 / 11 / 2022
Hyd. No. 11
COMBINED OUTFLOW
Hydrograph type
= Combine
Peak discharge
= 17.77 cfs
Storm frequency
= 10 yrs
Time to peak
= 718 min
Time interval
= 2 min
Hyd. volume
= 40,650 cuft
Inflow hyds.
= 9
Contrib. drain. area
= 3.950 ac
Q (cfs)
18.00
15.00
12.00
• m
.1M
3.00
COMBINED OUTFLOW
Hyd. No. 11 -- 10 Year
Q (cfs)
18.00
15.00
12.00
• tt
ME
3.00
0.00
120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 11 —Hyd No. 9 Time (min)
Page 40 of 78
Hydrograph Report
18
HydraBow Hydrographs Extension for Autodesk® Civil 3138 by Autodesk, Inc. v2022
Hyd. No. 1
PRE -DEVELOPMENT
Hydrograph type
= SCS Runoff
Storm frequency
= 100 yrs
Time interval
= 2 min
Drainage area
= 6.280 ac
Basin Slope
= 0.0 %
Tc method
= TR55
Total precip.
= 9.16 in
Storm duration
= 24 hrs
* Composite (Area/CN) = [(3.950 x 74) + (2.330 x 66)] / 6.280
Q (cfs)
60.00
50.00
30.00
20.00
10.00
0.00 -'
0
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
PRE -DEVELOPMENT
Hyd. No. 1 -- 100 Year
Friday, 02 / 11 / 2022
= 55.38 cfs
= 718 min
= 127,683 cult
= 71*
= Oft
= 7.20 min
= Type II
= 484
Q (cfs)
60.00
50.00
1 11
20.00
10.00
t 0.00
120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 1 Time (min)
Page 41 of 78
Hydrograph Report
19
HydraBow Hydrographs Extension for Autodesk® Civil 3138 by Autodesk, Inc. v2022
Hyd. No. 2
POST -DEVELOPMENT
Hydrograph type
= SCS Runoff
Storm frequency
= 100 yrs
Time interval
= 2 min
Drainage area
= 6.280 ac
Basin Slope
= 0.0 %
Tc method
= User
Total precip.
= 9.16 in
Storm duration
= 24 hrs
* Composite (Area/CN) = [(3.950 x 74) + (2.330 x 69)] / 6.280
Q (cfs)
60.00
50.00
30.00
20.00
10.00
0.00 -'
0
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
POST -DEVELOPMENT
Hyd. No. 2 -- 100 Year
Friday, 02 / 11 / 2022
= 56.50 cfs
= 718 min
= 130,527 cult
= 72*
= Oft
= 7.20 min
= Type II
= 484
Q (cfs)
60.00
50.00
1 11
20.00
10.00
— 0.00
120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 2 Time (min)
Page 42 of 78
I
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Friday, 02 / 1112022
Hyd. No. 4
PRE-DEV POND
Hydrograph type
= SCS Runoff
Peak discharge
= 18.38 cfs
Storm frequency
= 100 yrs
Time to peak
= 718 min
Time interval
= 2 min
Hyd. volume
= 42,090 cuft
Drainage area
= 2.330 ac
Curve number
= 66
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 7.20 min
Total precip.
= 9.16 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Q (Cfs)
21.00
18.00
15.00
12.00
• 11
. M
3.00
PRE-DEV POND
Hyd. No. 4 -- 100 Year
Q (cfs)
21.00
18.00
15.00
12.00
• 11
M
3.00
0.00 1 1 1' ' 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 4 Time (min)
Page 43 of 78
Hydrograph Report
21
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Hyd. No. 5
POST-DEV TO POND
Hydrograph type
= SCS Runoff
Storm frequency
= 100 yrs
Time interval
= 2 min
Drainage area
= 2.330 ac
Basin Slope
= 0.0 %
Tc method
= User
Total precip.
= 9.16 in
Storm duration
= 24 hrs
Q (cfs)
21.00
18.00
15.00
12.00
• 11
. M
3.00
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
POST-DEV TO POND
Hyd. No. 5 -- 100 Year
Friday, 02 / 1112022
= 19.70 cfs
= 718 min
= 45,261 cuft
= 69
= Oft
= 7.20 min
= Type II
= 484
Q (cfs)
21.00
18.00
15.00
12.00
• 11
M
3.00
0.00 1 1 1' ' 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 5 Time (min)
Page 44 of 78
Hydrograph Report
22
Hydraflow Hydrographs Extension for Autodesk® Civil 3138 by Autodesk, Inc. v2022
Hyd. No. 7
ROUTING
Hydrograph type
= Reservoir
Peak discharge
Storm frequency
= 100 yrs
Time to peak
Time interval
= 2 min
Hyd. volume
Inflow hyd. No.
= 5 - POST-DEV TO POND
Max. Elevation
Reservoir name
= POND
Max. Storage
Storage Indication method used.
Q (cfs)
21.00
18.00
15.00
12.00
moo
t
. m
3.00
ROUTING
Hyd. No. 7 -- 100 Year
Friday, 02 / 11 / 2022
= 18.01 cfs
= 722 min
= 45,260 tuft
= 443.87 ft
= 6,466 cuft
Q (Cfs)
21.00
18.00
15.00
12.00
• tI
3.00
0.00 ' I I I I I 10.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
— Hyd No. 7 —Hyd No. 5 ®Total storage used = 6,46E cult Time (min)
Page 45 of 78
23
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Friday, 02 / 1112022
Hyd. No. 9
OFFSITE
Hydrograph type
= SCS Runoff
Peak discharge
= 36.90 cfs
Storm frequency
= 100 yrs
Time to peak
= 718 min
Time interval
= 2 min
Hyd. volume
= 85,673 cuft
Drainage area
= 3.950 ac
Curve number
= 74
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 8.30 min
Total precip.
= 9.16 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Q (Cfs)
40.00
30.00
20.00
10.00
0.00
0 120 240
Hyd No. 9
OFFSITE
Hyd. No. 9 -- 100 Year
360 480 600 720 840
Q (cfs)
40.00
20.00
10.00
0.00
960 1080 1200 1320 1440
Time (min)
Page 46 of 78
Hydrograph Report
24
Hydratlow Hydrographs Extension for Autodesk® civil 3138 by Autodesk, Inc. v2022
Friday, 02 / 11 / 2022
Hyd. No. 11
COMBINED OUTFLOW
Hydrograph type = Combine
Peak discharge
= 36.90 cfs
Storm frequency = 100 yrs
Time to peak
= 718 min
Time interval = 2 min
Hyd. volume
= 85,673 cuft
Inflow hyds. = 9
Contrib. drain. area
= 3.950 ac
N 141.11.14 9XIIII14 U KGITA
Q (cfs) Q (cfs)
Hyd. No. 11 -- 100 Year
40.00 40.00
30.00 30.00
20.00 20.00
10.00 10.00
0.00 - 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440
Hyd No. 11 — Hyd No. 9 Time (min)
Page 47 of 78
Hydraflow Rainfall Report
25
Hydrallow Hydrographs Extension for Autodesk® Civil 3138 by Autodesk, Inc. v2022
Return
Period
Intensity -Duration -Frequency Equation Coefficients (FHA)
(Yrs)
B
D
E
(WA)
1
0.0000
0.0000
0.0000
---
2
53.4281
12.5000
0.8941
----
3
0.0000
0.0000
0.0000
-----
5
75.7517
14.2000
0.8271
----
10
50.0721
10.7000
0.7889
-----
25
103.3028
16.6000
0.8227
-----
50
116.5747
17.3000
0.8234
------
100
124.5731
17.6000
0.8144
-----
File name: SampleFHA.idf
Intensity = B I (Tc + D)AE
Friday, 02 / 11 / 2022
Return
Penal
Intensity Values (in/hr)
(Yrs)
5 min
10
15
20
25
30
35
40
45
50
55
60
1
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
2
4.13
3.30
2.76
2.38
2.09
1.87
1.69
1.55
1.43
1.32
1.24
1.16
3
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
5
6.58
5.43
4.65
4.08
3.64
3.30
3.02
2.79
2.59
2.42
2.28
2.15
10
5.70
4.59
3.87
3.36
2.98
2.69
2.46
2.26
2.10
1.96
1.84
1.74
25
825
6.95
6.03
5.34
4.81
4.38
4.03
3.73
3.48
3.26
3.08
2.91
50
9.05
7.66
6.67
5.92
5.34
4.87
4.48
4.16
3.88
3.64
3.43
3.25
100
9.83
8.35
7.30
6.49
5.87
5.36
4.94
4.59
4.29
4.03
3.80
3.60
Tc = time in minutes. Values may exceed 60.
Preci . file name: Sam le. c
Rainfall Precipitation Table (in)
Stone
Distribution
1-yr
2-yr
3-yr
S-yr
10-yr
25-yr
50-yr
100-yr
SCS 24-hour
3.05
3.69
0.00
3.30
5.58
5.77
6.80
9.16
SCS 6-Hr
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Huff -1st
0.00
0.00
0.00
2.75
0.00
0.00
6.50
0.00
Huff-2nd
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Huff-3rd
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Huff4th
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Huff-Indy
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Custom
0.00
0.00
0.00
2.80
0.00
0.00
6.00
0.00
Page 48 of 78
APPENDIX A
ARMY CORPS APPROVAL LETTER (EMAIL)
APPENDIX B
HYDRAFLOW REPORT FOR EXTENDED
DETENTION POND
APPENDIX C
APPENDIX D
NUTRIENT CREDIT AVAILABILITY LLETTER
APPENDIX E
NRCS SOILS REPORT
Page 49 of 78
tleia Iowa refls
conrtantvalues
Project Name:
Date:
SOUTHWOOD- FILL IN NORTHERN AREA WEDGE
2/7/2022
Linear Develop m e or PrajeLt7
No
calculation cells
Site Information
Post -Development Project (Treatment Volume and Loads)
Enter Total Disturbed Area (acres) 1.D1
•
®i.
Pre-ReDevelopment Land Cover (acres)
Check:
aMI Design SpetifiroNGns list
2013 Iran Stds&Specs
linearpruject?
La M rover areas enteredcorrecNy7
Total disturbed area entered?
NO
�I
A Sails
Issors
Csells
DSoils
Torah
Forest/Open Space (worse) N
forest/open space
0.98
0.08
Manged Turf (words)- disturbed, graded for
pros or other tuff to be mowed/maned
0.00
0.00
Imperdous Loser lades)
om
0.03
1.01
Post0eveloprDent Land Cover (acres)
A sails
Bsoils
Csells
DSoils
radicals
lases)-undiswehed.
p.meaea mresi/apen spare or remrened una
0'00
Managed Turf (wres)-disturbed, graded for
pros or other tuff robe mowed/maned
0.92
1
0.92
Impervious Coser(e.)
009
0.09
Area Check
OK.
OIL
OK.
DR.
1.01
Constants
Runoff Coefficients
Rv
Annual Rainfall(intlra)
43
ASolh
risers
CSails
Dsells
Target Rainfall Eeent(inches)
1.00
F-./Open spare
0.02
0.03
0.04
0.05
Total Phosphorus(TP) EMC(mg/L)
0.26
Managetl Turf
0.15
0.20
0.22
0.25
TOt.1 NRmgen(TY) EMC(mp/L)
1.86
Impervnus cover
OAS
0.95
0.95
0.95
Target TP Lnd(11shcre/yr)
0.41
N(uniff- correction factor)
0.90
P •
P •LAND
COVER
SUMMARY POST
DEVELOPMENT
Lantl Cover Summary-Fre
LaM Laver SummaMPost (Final)
WMLoverSummary-Fast
L Cdsod, rmryPost
PreReReek,snent
Listed
Post Neaev. 4 New impervious
Post-ReOerelapnmt
pace (acres)
/Opens o er
0.98C
forest/Openspace
10 ac
0.40
Forest/Open spaceFore
carer ao
i rrWorhtal
Rv(frort)
0.03
MAdjusted'
Weighted Re(foren)
0.00
Weidffal Rs(farest)%Forest
%ForestManagNTurf
97%
%Forest
0%
Corer acres)
0.00
ManagedTurt Cwer
092
Managed Turf OwerWeighted
Rv(turf)
0.00
Weidued Rv(turf)
0.20
Weidstni Rv(Nrn
Page 50 of 78
%Managed Turf
0%
0%
%MaragMTurf
91%
%Managed Turf
97%
Newlmpernom[over
0.O6.
Impwir-C laved
0.03
0.03
bupenmus Lover
am
Fares Impervious
0.03
(aver)
Caner (acres)
(acres)
Rv(Impervinus)
0.95
0.95
R.(Imperdous)
0.95
Rv(impervious)
0.95
Rv(imperviausl
0.95
%Impervious
3%
3%
%Impervious
Snt
%Impervious
3%
Teral sae Arc. (ayes)
L01
095
FuVlgire Ama(acres)
1.131
TWI ReDev. Site Area
0.95
Sire Rv
0.06
0m
FirelP.Dery Sae Rv
0.27
ReDev SaeM
an
Treatment Volume and
Nutrient Load
Treatment
Volume and
Nutrient Load
Pre-ReDeveloPment Treatment Volume
Finlemr-Rvebpmen[
Pall-ReDevd
Pint-Devebpmmt
(azrea)
0.000R
O.00dJ
Trhnent m Volue
ea
0.0225
T..Val... dume
0.OIZ]
Treahned Vabvne
0.00d8
(azre-a)
Iaerek)
(sere*)
FiNPoeennVlurnen[
Post-R.D
Postnt
Pre-ReDevelopmem Treatment Volume
230
206
Tre(mbic Vdume
9J8
Voluenl
TreahnmlVd)
JJI
Volumeen[
Treatment Volume (cubic
20J
(mbicrem)
(abicfeeQ
(ruticfM)
feet)
Post-0evelopmed TP
Pre-ReOevelopmen[ TP Load
Final Post.TI
Post-Readins)ment
0.13
0.13
Development TP Load
0.61
.
ImdpP)
OAR
0.13
(Ib/yr)
(IS/Yr)
(uhdv
Lind llb/w)
Pre-Fe.rI.ImmtTP Loarper—
Final Post-neuelopmem TP
Port-bebeaelm-1 TP
pb/.ne/err)
bL3
A.3
la.dper.rre
m.dper.rre
Ilb/azre/yq
Ub/arm/rr)
Baseline TP Load (Ib/yr)
Mm. Reduction Required
R..Wava/yr applied. Innewimurnm[ area c.Iluding Irsiws
a39
melow Poe
20X
6MpmposelNrnewlmpewbusmver)
Recevelopment Load)
'Adjusted LaMCmmrsummory:
TP Load Reduction
TIP Load Reduction
Pre ReDevelopment land cover minus pervwus bad mver(fam L/apen spore ar
Required for
0.10
Required for New
0.11
mormged turf) ocreoge pmposedforne impetuous mver
Redevelopetl Are
Impamim us Area(lb/yr)
(lb/yr)
Adjurtedt Wfacrmgeismnsistentwdh Port-ReD vebpmentovmge(minus ocreoge
ofne imperviausroser)
x Reductim below new development load
limdatimmtre9uired
Column I shows Read redur lion mgmlement for new impervious cover (based m new
dew•bpment bad limit 0431hs/a—liasaf.
Post -Development
TP Load Reduction Required (Ib/yr)
0.20
Nitrogen Loads (Informational Purposes
Only)
Final Laad
TNPoatb9APrebeDeuelopmmt
N
oad(lb/y)
0.
mbpmmt
(PortNew Impervious)
q.da
(lb/yr)
.Page 51 of 78
Drainage AmaA
Smrm r Bart ManagemaM Pmrt ws (RR= Runoff R uNian)
.mi nem.mmam.ue.. m.m. i. Da A (IWM
vm,.emWP�mAn..m,m,v.umeWva Alai "e
P.xlka
.�bn
.1.)
X
MM1Am
M'.,m•lu
Imp Wm
[ev4e®
Am Wal
veWneM1m
UW .
arein'1 xamW.PTI
Mn. ,
mN
.0 iai
imIBMI
Pmpimm
vnl
mr lw
Pmpimm
mYWum Pmmgmnu4®1
mA.i mPi
Ibq.me
meats
meowM
Rem.WM
nWMs4m.1
a.l
Os Imme
"m^bea
Te.ment
.miWi
2. x,i
s.I .
:n Sml ,ow...
2.
mm1—nwm&ifw.<:�
.f
o mf
i
�no«e:f
�fwaas'�.00maow
o
m PIRm
aw w
20
.ws.w
.Fuse:f
N. , aM1m.mWw ma Nftm.m .
m M1mmm n a .maw a M1
em,�.i . mnWa ke W.mew Pm.mJ., n..i
., text
.m
0
txei
0
W.ww
0
0
b. �aaf
.a text
ommmo
a,loP mfxxf
Page 52 of 78
A IF FURE, AM
TREATED
TOTAL IMPERVIOUS OWN ,_,
iED,p 9i dEIX. ON.
TOTALRUNOFFREDUCWNINDa AM)
a AIINM
aaIIUM
TOTu wOmxnxxs RE MAININO AFTER ARRLYI xO RUNOFF REDUCTION xMOIOs IN Da A PIAEfl El
S..EERQUALITYCOMP .TABMF'FrCCOMVLNNCCGLCFILAT10N5
OFFEELL pe,�
muuaxtaRHOUS ETR OVRUEDTEDpc, CARRACHUCK iOR.
TmuxxmrxaxusxEMO LREODIMONMTEDWM
AA :LN ,
A . A DRUM,
TmaLRxosxx aADRNM
TOTAL NHOAELEARUE,
A.
TOTURxasRxoxus REMAIWnNNIND AFTEeAFnvmO IMP WAD REDUCTIONS IN D.A. A DRNn,
SEE WATER EQUALITY COMPLIANCE TAB FOR SITE COMPLIANCE CALCULATIONS
an11NM�
NO
NOEx REmwxuwrtxuTT an11NM
TOTAL MOREN REMOVED IN Da A DRUM
Page 53 of 78 Ns».
Site Results (Water Quality Compliance)
Area Checks
DA. A
D.A. B
DA. C
D.A. D
D.A. E
AREA [HECK
FOREST/OPEN SPACE (ac)
0.00
0.00
0.00
0.00
0.00
OK.
IMPERVIOUS COVER(at)
0.09
0.00
0.00
0.00
0.00
OK.
IMPERVIOUS COVER TREATED(at)
0.09
0.00
E0.00
0.00
0.00
0.00
OK.
MANAGED TURF AREA(at)
0.92
0.00
0.00
0.00
0.00
OK.
MANAGED TURF AREA TREATED (at)
0.92
0.00
0.00
0.00
OK.
AREA CHECK
978
Site Treatment Volume (fe)
Runoff Reduction Volume and TP By Drainage Area
D.A. A
D.A. B
D.A. C
D.A. DI
D.A. E
TOTAL
RUNOFF REDUCTION VOLUME ACHIEVED(N)
0
0
0
0
0
0
TP LOAD AVAILABLE FOR REMOVAL (Ib/yr)
0.61
0.00
0.00
0.00
0.00
0.61
TP LOAD REDUCTION ACHIEVED (Ib/yr)
0.09
0.00
0.00
0.00
0.00
0.09
TP LOAD REMAINING (Ib/yr)
0.52
0.00
0.00
0.00
0.00L
0.52
NITROGEN LOAD REDUCTION ACHIEVED (Ib/yre
.44 0.00
0.00
0.00
0.00
0.44
0.61
Total Phosphorus
FINAL POST -DEVELOPMENT TP LOAD(Ib/yr)
TP LOAD REDUCTION REQUIRED (Ib/yr)
0.20
TP LOAD REDUCTION ACHIEVED (Ib/yr)
0.09
TP LOAD REMAINING (Ib/yr):
0.52
REMAINING TP LOAD REDUCTION REQUIRED (Ib/yr):
0.11
Total Nitrogen (For Information Purposes)I
POST -DEVELOPMENT LOAD(Ib/yr)
4.40
NITROGEN LOAD REDUCTION ACHIEVED (Ib/yr)jj
0.44
REMAINING POST -DEVELOPMENT NITROGEN LOAD (Ib/yr
3.96
Page 54 of 78
Virginia Runag Reduction Metho l WOMsheet
DEQ Virginia Runoff Reduction Method Re -Development Compliance Spreadsheet - Version 3.0
BMP Design Specifications List: 2013 Dmft Stds & Specs
Site Summary
Project Title: SOUTHWOOD-FILL IN NORTHERN AREA WEDGE
Date: 44599 Total Rainfall (in): 4;
Total Disturbed Acreage: 1.01
Site Land Cover Summary
Pre-ReDevelopment Land Cover (acres)
A soils
BSons
CSolls
DSoils
Totals
%of Total
Forert/Open (acres)
0.00
0.98
0.00
0.00
0.98
97
Managed Turf(acres)
0.00
0.00
0.00
0.00
0.00
0
Impervious Cover (acres)
0.00
0.03
0.00
0.00
0.03
3
1.01
100
Past-ReDevelopment Land Cover (acres)
A soils
Bsolls
CSolls
DSoils
Totals
%of Total
Forest/Open (acres)
0.00
0.00
0.00
0.00
0.00
0
Managed Turf (acres)
0.00
0.92
0.00
0.00
0.92
91
Impervious Cover(acres)
0.00
0.09
0.00
0.00
0.09
9
1.01
100
Site Tv and Land Cover Nutrient Loads
Final Post -Development
Post
Post-
Adjusted Pre -
(Post-ReDevelopment
ReDevelopment
Development
ReDevelopment
& New Impervious )
(New Impervious)
Site Rv
0.27
0.22
0.95
0.06
Treatment Volume (ft')
978
771
207
204
TP Load (lb/yr)
0.61
0.48
0.13
0.13
Baseline TP Load (jb/yr): 0.3895' 'Reduction below new developmenuaadlimimtion notrequired
Total TP Load Reduction Required(lb/yr) 0.20 0.10 0.11
Final Post -Development Load
(Post-ReDevelopment & New Impervious)
Pre-
ReDevelopment
TN Load (lb/yr)
4.40
0.94
Pre-
ReDevelopment
Final Post -Development
Post-ReDevelopment TP
TP Load per acre
TP Load per acre
Load per acre
lb/acre/ r
(lb/acre/yr)
(lb/acre/yr)
0.13
0.61
o.S1
Summary Print Page 55 of 78
Virginia Ru tag Reduction Method! Worlsheet
_.._.._.._.._.._..-.-_.__.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._.._..
Site Compliance Summary
Maximum% Reduction Required Belo m% 'Note:% Reduction will reduce post -development TP load to less than or equal to baseline load of0.39 lb/yr(0.411b/ac/yr)
PrnReDevelopmeat Loatl (Required reductionfor Post -ReDev.=Post-ReDev TP load -baseline load of0.3895 lb/yr), baseline load= site area x 0.4116/aOT
Total Runoff Volume Reduction (kt)
0
Total TP Load Reduction Achieved (lb/yr)
0.09
Total TN Load Reduction Achieved (lb/yr)
0.44
Remaining Post Development TP Load
0.52
(Ib/yr)
Remaining TP Load Reduction(lb/yr
Required
0.11
`Reduction below new development load limitation not required
Summary Print Page 56 of 78
Virginia Runag Reduction Method WOMsheet
_. _ _ _. _.. _. _ _ _. _.. _. _ _ _. _.. _. _ _ _. _.. _. _ _ _. _.. _. _ _ _. _.. _. _ _ _. _.. _. _ _ _. _.. _. _ _ _. _.. _. _ _ _. _.. _. _ _ _. _.. _. _ _ _. _.. _. _ _ _. _.. _. _ _ _. _.. _. _ _ _. _.. _. _ _ _. _.. _. - _ -.
Drainage Area Summary
D.A. A
DA. B
D.A. C
D.A. D
D.A. E
Total
Forest/Open (acres)
0.00
0.00
0.00
0.00
0.00
0.00
Managed Turf(acres)
0. 22
0.00
0.00
0.00
0.00
0.92
Impervious Cover (acres)
0.09
0.00
0.00
0.00
0.00
0.09
Total Area (acres)
1.01
0.00
0.00
0.00
0.00
1.01
Drainage Area Compliance Summary
D.A. A
DA. B
D.A. C
DA. D
D.A. E
Total
TP Load Reduced (lb/yr)
1 0.09
1 0.00
0.00
1 0.00
0.D0
1 0.09
TN Load Reduced (lb/yr)
1 0.44
1 0.00
0.00
1 0.00
0.00
1 0.44
Sura nary Print Page 57 of 78
Virginia Runag Reduction Method! WoMsheet
----------------------------------------------------------------------------------------
Runoff Volume and CN Calculations
1-yearstorm 2-yearstorm 10-yearstorm
target Rainfall Event (in) 1 0.00 0.00 0.00
Drainage Areas
RV&CN
Drainage AreaA
Drainage Areall
Drainage AreaC
Drainage Area
Drainage Area
CN
GC
0
0
0
0
RR (ft)
0
0
0
0
0
1-year return period
RV via an(ws-in)
0.W
0.00
0.00
0.00
0.00
RVw RR(wein)
0.W
0.00
0.00
0.00
0.00
CN ad)uaxee
100
0
0
0
0
2-year return period
RV wo an(ws-in)
0.00
0.00
0.00
0.00
0.00
RVw RR(voin)
0.W
0.00
0.00
0.00
0.00
CN ad)uated
100
0
0
0
0
10-year return period
RVwo RRw'.)
0.00
0.00
0.00
0.00
0.00
RVw RR (wsin)
0.00
0.00
0.00
0.00
0.00
CN ad(uatea
1o0
0
0
0
0
Sura nary Print Page 58 of 78
APPENDIX A
ARMY CORPS APPROVAL LETTER (EMAIL)
APPENDIX B
HYDRAFLOW REPORT FOR EXTENDED
DETENTION POND
APPENDIX C
APPENDIX D
NUTRIENT CREDIT AVAILABILITY LLETTER
APPENDIX E
NRCS SOILS REPORT
Page 59 of 78
%6-yIRGINIA
NUTRIENT BANK
P.O. Box 142 Penn Laird, VA 22846 - (540) 217-4079 emiaMltrienlank.corn
December 23, 2021
Michael Myers, PE, CFM
30 Scale, LLC
871 Justin Drive
Palmyra, VA 22963
Re: Nutrient Credit Availability — Southwood - Northern Area Wedge - Site Plan
Mr. Myers,
The Virginia Nutrient Bank (VNB) is pleased to confirm availability 041t pounds per year of phosphorus
offsets (nutrient credits) for the Southwood - Northern Area Wedge site plan located at a portion of Tax
Map 90A1-ID at the intersection of Bitternut Lane, Fin Court and Iris Court in Albemarle County. The
project drains to HUC: 02080204.
VNB has approval from the Virginia Department of Environmental Quality (VDEQ) for Nonpoint Source
Offset Generation Certification. VNB is approved to transfer nutrient credits in accordance with the
Chesapeake Bay Watershed Nutrient Credit Exchange Program (VA Code 62.1-44.19:14 et seq). These
offsets are also transferable in accordance with the Virginia stormwater offset program (VA Code 62.1-
44.15:35) and the Virginia Soil and Water Conservation Board's Guidance Document on Stormwater
Nonpoint Nutrient Offsets approved on July 23, 2009, to those regulator entities qualifying for nutrient
offsets.
VNB is managing the Upper James Nutrient Bank in Nelson County that will generate approximately
155.31 pounds of phosphorus reduction and roughly 555.15 pounds of nitrogen reduction per year within
the 02080203 IIUC. VNB will retire 0.431 pounds of phosphorus credits and corresponding nitrogen
credits from the Upper James Nutrient Bank in accordance with the Nutrient Offset Certification
regulations.
Respectfully, I )-
Gordon D. Weirich
Virginia Nutrient Bank, LLC
gordon@virginianutrientbank.com 1 540-217-4079
Page 60 of 78
APPENDIX A
ARMY CORPS APPROVAL LETTER (EMAIL)
APPENDIX B
HYDRAFLOW REPORT FOR EXTENDED
DETENTION POND
APPENDIX C
APPENDIX D
NUTRIENT CREDIT AVAILABILITY LLETTER
APPENDIX E
NRCS SOILS REPORT
Page 61 of 78
USDA United States
Department of
Agriculture
N RCS
Natural
Resources
Conservation
Service
A product of the National
Cooperative Soil Survey,
a joint effort of the United
States Department of
Agriculture and other
Federal agencies, State
agencies including the
Agricultural Experiment
Stations, and local
participants
Custom Soil Resource
Report for
Albemarle
County, Virginia
OM-NIAM21, 2021
Preface
Soil surveys contain information that affects land use planning in survey areas.
They highlight soil limitations that affect various land uses and provide information
about the properties of the soils in the survey areas. Soil surveys are designed for
many different users, including farmers, ranchers, foresters, agronomists, urban
planners, community officials, engineers, developers, builders, and home buyers.
Also, conservationists, teachers, students, and specialists in recreation, waste
disposal, and pollution control can use the surveys to help them understand,
protect, or enhance the environment.
Various land use regulations of Federal, State, and local governments may impose
special restrictions on land use or land treatment. Soil surveys identify soil
properties that are used in making various land use or land treatment decisions.
The information is intended to help the land users identify and reduce the effects of
soil limitations on various land uses. The landowner or user is responsible for
identifying and complying with existing laws and regulations.
Although soil survey information can be used for general farm, local, and wider area
planning, onsite investigation is needed to supplement this information in some
cases. Examples include soil quality assessments (http://www.nrGs.usda.govtwps/
portal/nres/main/soils/healthn and certain conservation and engineering
applications. For more detailed information, contact your local USDA Service Center
(https:Hoffices.sc.egov.usda.gov/locator/app?agency=nres) or your NRCS State Soil
Scientist (http://www.nrGs.usda.govtwps/portal/nres/detail/soils/c ontactus/?
cid=nres 142p2_053951).
Great differences in soil properties can occur within short distances. Some soils are
seasonally wet or subject to flooding. Some are too unstable to be used as a
foundation for buildings or roads. Clayey or wet soils are poorly suited to use as
septic tank absorption fields. A high water table makes a soil poorly suited to
basements or underground installations.
The National Cooperative Soil Survey is a joint effort of the United States
Department of Agriculture and other Federal agencies, State agencies including the
Agricultural Experiment Stations, and local agencies. The Natural Resources
Conservation Service (NRCS) has leadership for the Federal part of the National
Cooperative Soil Survey.
Information about soils is updated periodically. Updated information is available
through the NRCS Web Soil Survey, the site for official soil survey information.
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its
programs and activities on the basis of race, color, national origin, age, disability,
and where applicable, sex, marital status, familial status, parental status, religion,
sexual orientation, genetic information, political beliefs, reprisal, or because all or a
part of an individual's income is derived from any public assistance program. (Not
all prohibited bases apply to all programs.) Persons with disabilities who require
Page 63 of 78
alternative means for communication of program information (Braille, large print,
audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice
and TDD). To file a complaint of discrimination, write to USDA, Director, Office of
Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or
call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity
provider and employer.
Page 64 of 78
Contents
Preface....................................................................
How Soil Surveys Are Made .................................
SoilMap..................................................................
c�a KA�r
Legend..........................................................................
MapUnit Legend...........................................................
Map Unit Descriptions...................................................
Albemarle County, Virginia ........................................
2713—Elioak loam, 2 to 7 percent slopes ...............
27C—Elioak loam, 7 to 15 percent slopes .............
39D—Hazel loam, 15 to 25 percent slopes...........
References......................................................................
............... 2
...............5
.8
..9
10
11
Page 65 of 78
How Soil Surveys Are Made
Soil surveys are made to provide information about the soils and miscellaneous
areas in a specific area. They include a description of the soils and miscellaneous
areas and their location on the landscape and tables that show soil properties and
limitations affecting various uses. Soil scientists observed the steepness, length,
and shape of the slopes; the general pattern of drainage; the kinds of crops and
native plants; and the kinds of bedrock. They observed and described many soil
profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The
profile extends from the surface down into the unconsolidated material in which the
soil formed or from the surface down to bedrock. The unconsolidated material is
devoid of roots and other living organisms and has not been changed by other
biological activity.
Currently, soils are mapped according to the boundaries of major land resource
areas (MLRAs). MLRAs are geographically associated land resource units that
share common characteristics related to physiography, geology, climate, water
resources, soils, biological resources, and land uses (USDA, 2006). Soil survey
areas typically consist of parts of one or more MLRA.
The soils and miscellaneous areas in a survey area occur in an orderly pattern that
is related to the geology, landforms, relief, climate, and natural vegetation of the
area. Each kind of soil and miscellaneous area is associated with a particular kind
of landform or with a segment of the landform. By observing the soils and
miscellaneous areas in the survey area and relating their position to specific
segments of the landform, a soil scientist develops a concept, or model, of how they
were formed. Thus, during mapping, this model enables the soil scientist to predict
with a considerable degree of accuracy the kind of soil or miscellaneous area at a
specific location on the landscape.
Commonly, individual soils on the landscape merge into one another as their
characteristics gradually change. To construct an accurate soil map, however, soil
scientists must determine the boundaries between the soils. They can observe only
a limited number of soil profiles. Nevertheless, these observations, supplemented
by an understanding of the soil -vegetation -landscape relationship, are sufficient to
verify predictions of the kinds of soil in an area and to determine the boundaries.
Soil scientists recorded the characteristics of the soil profiles that they studied. They
noted soil color, texture, size and shape of soil aggregates, kind and amount of rock
fragments, distribution of plant roots, reaction, and other features that enable them
to identify soils. After describing the soils in the survey area and determining their
properties, the soil scientists assigned the soils to taxonomic classes (units).
Taxonomic classes are concepts. Each taxonomic class has a set of soil
characteristics with precisely defined limits. The classes are used as a basis for
comparison to classify soils systematically. Soil taxonomy, the system of taxonomic
classification used in the United States, is based mainly on the kind and character
of soil properties and the arrangement of horizons within the profile. After the soil
5 Page 66 of 78
Custom Soil Resource Report
scientists classified and named the soils in the survey area, they compared the
individual soils with similar soils in the same taxonomic class in other areas so that
they could confirm data and assemble additional data based on experience and
research.
The objective of soil mapping is not to delineate pure map unit components; the
objective is to separate the landscape into landforms or landform segments that
have similar use and management requirements. Each map unit is defined by a
unique combination of soil components and/or miscellaneous areas in predictable
proportions. Some components may be highly contrasting to the other components
of the map unit. The presence of minor components in a map unit in no way
diminishes the usefulness or accuracy of the data. The delineation of such
landforms and landform segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, onsite
investigation is needed to define and locate the soils and miscellaneous areas.
Soil scientists make many field observations in the process of producing a soil map.
The frequency of observation is dependent upon several factors, including scale of
mapping, intensity of mapping, design of map units, complexity of the landscape,
and experience of the soil scientist. Observations are made to test and refine the
soil -landscape model and predictions and to verify the classification of the soils at
specific locations. Once the soil -landscape model is refined, a significantly smaller
number of measurements of individual soil properties are made and recorded.
These measurements may include field measurements, such as those for color,
depth to bedrock, and texture, and laboratory measurements, such as those for
content of sand, silt, clay, salt, and other components. Properties of each soil
typically vary from one point to another across the landscape.
Observations for map unit components are aggregated to develop ranges of
characteristics for the components. The aggregated values are presented. Direct
measurements do not exist for every property presented for every map unit
component. Values for some properties are estimated from combinations of other
properties.
While a soil survey is in progress, samples of some of the soils in the area generally
are collected for laboratory analyses and for engineering tests. Soil scientists
interpret the data from these analyses and tests as well as the field -observed
characteristics and the soil properties to determine the expected behavior of the
soils under different uses. Interpretations for all of the soils are field tested through
observation of the soils in different uses and under different levels of management.
Some interpretations are modified to fit local conditions, and some new
interpretations are developed to meet local needs. Data are assembled from other
sources, such as research information, production records, and field experience of
specialists. For example, data on crop yields under defined levels of management
are assembled from farm records and from field or plot experiments on the same
kinds of soil.
Predictions about soil behavior are based not only on soil properties but also on
such variables as climate and biological activity. Soil conditions are predictable over
long periods of time, but they are not predictable from year to year. For example,
soil scientists can predict with a fairly high degree of accuracy that a given soil will
have a high water table within certain depths in most years, but they cannot predict
that a high water table will always be at a specific level in the soil on a specific date.
After soil scientists located and identified the significant natural bodies of soil in the
survey area, they drew the boundaries of these bodies on aerial photographs and
6 Page 67 of 78
Custom Soil Resource Report
identified each as a specific map unit. Aerial photographs show trees, buildings,
fields, roads, and rivers, all of which help in locating boundaries accurately.
Page 68 of 78
Soil Map
The soil map section includes the soil map for the defined area of interest, a list of
soil map units on the map and extent of each map unit, and cartographic symbols
displayed on the map. Also presented are various metadata about data used to
produce the map, and a description of each soil map unit.
Page 69 of 78
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Page 70 of 78
MAPLEGEND
Area of Interest (AOI)
O
Area of Interest (AOI)
Solis
O
Soil Map Unit Polygons
,•.,I
Soil Map Unit Lines
Soil Map Unit Points
Special
Point Features
V
Blowout
®
Borrow Pit
Clay Spot
Q
Closed Depression
Gravel Pit
Gravelly Spot
0
Landfill
A.
Lava Flow
Marsh or swamp
Mine or Quarry
O
Miscellaneous Water
O
Perennial Water
y
Rock Outcrop
+
Saline Spot
Sandy Spot
Severely Eroded Spot
o
Sinkhole
Slide or Slip
$odic Spot
Custom Soil Resource Report
Spoil Area
®
Stony Spot
W
Very Stony Spot
Wet Spot
0
Other
•�
Special Line Features
Water Features
Streams and Canals
Transportation
4_14
Rails
^/
Interstate Highways
N
US Routes
Major Roads
Local Roads
Background
. Aerial Photography
MAP INFORMATION
The soil surveys that comprise your AOI were mapped at
1:15,800.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Albemarle County, Virginia
Survey Area Data: Version 15, Sep 13, 2021
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Oct 14, 2019—Oct
15, 2019
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
10 Page 71 of 78
Custom Soil Resource Report
Map Unit Legend
Map Unit Symbol
Map Unit Name '
Acres in AOI
Percent of AOI
27B
Elioak loam, 2 to 7 percent
slopes
3.4
48.5%
27C
Elioak loam, 7 to 15 percent
slopes
2.3
31.1%
39D
Hazel loam, 15 to 25 percent
slopes
1.7
22.5%
Totals for Area of Interest
7.4
100.0%
Map Unit Descriptions
The map units delineated on the detailed soil maps in a soil survey represent the
soils or miscellaneous areas in the survey area. The map unit descriptions, along
with the maps, can be used to determine the composition and properties of a unit.
A map unit delineation on a soil map represents an area dominated by one or more
major kinds of soil or miscellaneous areas. A map unit is identified and named
according to the taxonomic classification of the dominant soils. Within a taxonomic
class there are precisely defined limits for the properties of the soils. On the
landscape, however, the soils are natural phenomena, and they have the
characteristic variability of all natural phenomena. Thus, the range of some
observed properties may extend beyond the limits defined for a taxonomic class.
Areas of soils of a single taxonomic class rarely, if ever, can be mapped without
including areas of other taxonomic classes. Consequently, every map unit is made
up of the soils or miscellaneous areas for which it is named and some minor
components that belong to taxonomic classes other than those of the major soils.
Most minor soils have properties similar to those of the dominant soil or soils in the
map unit, and thus they do not affect use and management. These are called
noncontrasting, or similar, components. They may or may not be mentioned in a
particular map unit description. Other minor components, however, have properties
and behavioral characteristics divergent enough to affect use or to require different
management. These are called contrasting, or dissimilar, components. They
generally are in small areas and could not be mapped separately because of the
scale used. Some small areas of strongly contrasting soils or miscellaneous areas
are identified by a special symbol on the maps. If included in the database for a
given area, the contrasting minor components are identified in the map unit
descriptions along with some characteristics of each. A few areas of minor
components may not have been observed, and consequently they are not
mentioned in the descriptions, especially where the pattern was so complex that it
was impractical to make enough observations to identify all the soils and
miscellaneous areas on the landscape.
The presence of minor components in a map unit in no way diminishes the
usefulness or accuracy of the data. The objective of mapping is not to delineate
pure taxonomic classes but rather to separate the landscape into landforms or
11 Page 72 of 78
Custom Soil Resource Report
landform segments that have similar use and management requirements. The
delineation of such segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, however,
onsite investigation is needed to define and locate the soils and miscellaneous
areas.
An identifying symbol precedes the map unit name in the map unit descriptions.
Each description includes general facts about the unit and gives important soil
properties and qualities.
Soils that have profiles that are almost alike make up a soil series. Except for
differences in texture of the surface layer, all the soils of a series have major
horizons that are similar in composition, thickness, and arrangement.
Soils of one series can differ in texture of the surface layer, slope, stoniness,
salinity, degree of erosion, and other characteristics that affect their use. On the
basis of such differences, a soil series is divided into soil phases. Most of the areas
shown on the detailed soil maps are phases of soil series. The name of a soil phase
commonly indicates a feature that affects use or management. For example, Alpha
silt loam, 0 to 2 percent slopes, is a phase of the Alpha series.
Some map units are made up of two or more major soils or miscellaneous areas.
These map units are complexes, associations, or undifferentiated groups.
A complex consists of two or more soils or miscellaneous areas in such an intricate
pattern or in such small areas that they cannot be shown separately on the maps.
The pattern and proportion of the soils or miscellaneous areas are somewhat similar
in all areas. Alpha -Beta complex, 0 to 6 percent slopes, is an example.
An association is made up of two or more geographically associated soils or
miscellaneous areas that are shown as one unit on the maps. Because of present
or anticipated uses of the map units in the survey area, it was not considered
practical or necessary to map the soils or miscellaneous areas separately. The
pattern and relative proportion of the soils or miscellaneous areas are somewhat
similar. Alpha -Beta association, 0 to 2 percent slopes, is an example.
An undifferentiated group is made up of two or more soils or miscellaneous areas
that could be mapped individually but are mapped as one unit because similar
interpretations can be made for use and management. The pattern and proportion
of the soils or miscellaneous areas in a mapped area are not uniform. An area can
be made up of only one of the major soils or miscellaneous areas, or it can be made
up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example.
Some surveys include miscellaneous areas. Such areas have little or no soil
material and support little or no vegetation. Rock outcrop is an example.
12 Page 73 of 78
Custom Soil Resource Report
Albemarle County, Virginia
2713—Elioak loam, 2 to 7 percent slopes
Map Unit Setting
National map unit symbol: k1b8y
Elevation: 360 to 790 feet
Mean annual precipitation: 25 to 65 inches
Mean annual air temperature: 54 to 59 degrees F
Frost -free period: 195 to 231 days
Farmland classification: All areas are prime farmland
Map Unit Composition
Elioak and similar soils: 80 percent
Estimates are based on observations,
Description of Elioak
descriptions, and transects of the mapunit.
Setting
Landform: Hillslopes
Landform position (two-dimensional): Summit
Landform position (three-dimensional): Interfluve
Down -slope shape: Convex
Across -slope shape: Convex
Parent material: Residuum weathered from mica schist
Typical profile
H1 - 0 to 8 inches: loam
H2 - 8 to 39 inches: silty clay
H3 - 39 to 79 inches: silt loam
Properties and qualities
Slope: 2 to 7 percent
Depth to restrictive feature: More than 80 inches
Drainage class: Well drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat)
(0.20 to 1.98 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Moderately high to high
Available water supply, 0 to 60 inches: Moderate (about 6.6 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 2e
Hydrologic Soil Group: B
Hydric soil rating: No
13 Page 74 of 78
Custom Soil Resource Report
27C—Elioak loam, 7 to 15 percent slopes
Map Unit Setting
National map unit symbol: k1b8z
Elevation: 340 to 820 feet
Mean annual precipitation: 25 to 65 inches
Mean annual air temperature: 54 to 59 degrees F
Frost -free period: 195 to 231 days
Farmland classification: Farmland of statewide importance
Map Unit Composition
Elioak and similar soils: 80 percent
Estimates are based on observations,
Description of Elioak
descriptions, and transects of the mapunit.
Setting
Landform: Hillslopes
Landform position (two-dimensional): Summit
Landform position (three-dimensional): Interfluve
Down -slope shape: Convex
Across -slope shape: Convex
Parent material: Residuum weathered from mica schist
Typical profile
H1 - 0 to 8 inches: loam
H2 - 8 to 39 inches: silty clay
H3 - 39 to 79 inches: silt loam
Properties and qualities
Slope: 7 to 15 percent
Depth to restrictive feature: More than 80 inches
Drainage class: Well drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat)
(0.20 to 1.98 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Moderately high to high
Available water supply, 0 to 60 inches: Moderate (about 6.6 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 3e
Hydrologic Soil Group: B
Hydric soil rating: No
14 Page 75 of 78
Custom Soil Resource Report
39D—Hazel loam, 15 to 25 percent slopes
Map Unit Setting
National map unit symbol: kbb3
Elevation: 310 to 1,300 feet
Mean annual precipitation: 25 to 65 inches
Mean annual air temperature: 54 to 59 degrees F
Frost -free period: 195 to 231 days
Farmland classification: Not prime farmland
Map Unit Composition
Hazel and similar soils: 80 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Hazel
Setting
Landform: Hillslopes
Landform position (two-dimensional): Summit
Landform position (three-dimensional): Interfiuve
Down -slope shape: Convex
Across -slope shape: Convex
Parent material: Residuum weathered from graywacke sandstone and mica schist
Typical profile
H1 - 0 to 10 inches: loam
H2 - 10 to 20 inches: loam
H3 - 20 to 30 inches: channery loam
H4 - 30 to 79 inches: bedrock
Properties and qualities
Slope: 15 to 25 percent
Depth to restrictive feature: 20 to 40 inches to lithic bedrock
Drainage class: Excessively drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high
(0.20 to 5.95 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Available water supply, 0 to 60 inches: Low (about 4.1 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 4e
Hydrologic Soil Group: B
Hydric soil rating: No
15 Page 76 of 78
References
American Association of State Highway and Transportation Officials (AASHTO).
2004. Standard specifications for transportation materials and methods of sampling
and testing. 24th edition.
American Society for Testing and Materials (ASTM). 2005. Standard classification of
soils for engineering purposes. ASTM Standard D2487-00.
Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of
wetlands and deep -water habitats of the United States. U.S. Fish and Wildlife
Service FWS/OBS-79/31.
Federal Register. July 13, 1994. Changes in hydric soils of the United States.
Federal Register. September 18, 2002. Hydric soils of the United States.
Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric
soils in the United States.
National Research Council. 1995. Wetlands: Characteristics and boundaries.
Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service.
U.S. Department of Agriculture Handbook 18. http://www.nres.usda.gov/wps/portal/
nres/deta i I/nations I/soi Is/?cid=n res 142p2_054262
Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for
making and interpreting soil surveys. 2nd edition. Natural Resources Conservation
Service, U.S. Department of Agriculture Handbook 436. http://
www. nres.usda.gov/wps/portal/nres/detail/national/soils/?cid=nrGs142p2_053577
Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of
Agriculture, Natural Resources Conservation Service. http://
www. nres.usda.gov/wps/portal/nres/detail/national/soils/?cid=nres142p2_053580
Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and
Delaware Department of Natural Resources and Environmental Control, Wetlands
Section.
United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of
Engineers wetlands delineation manual. Waterways Experiment Station Technical
Report Y-87-1.
United States Department of Agriculture, Natural Resources Conservation Service.
National forestry manual. http://www.nres.usda.gov/wps/portal/nres/detail/soils/
home/?cid=nres 142p2_053374
United States Department of Agriculture, Natural Resources Conservation Service.
National range and pasture handbook. http:/twww.nres.usda.gov/wps/portal/nres/
detail/nationa I/land use/ra ng a pastu re/?cid=stelprd b 1043084
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Custom Soil Resource Report
United States Department of Agriculture, Natural Resources Conservation Service.
National soil survey handbook, title 430-VI. hftp://www.nres.usda.gov/wps/portal/
nres/detail/soils/scientists/?cid=nres 142p2_054242
United States Department of Agriculture, Natural Resources Conservation Service.
2006. Land resource regions and major land resource areas of the United States,
the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook
296. hftp://www.nres.usda.gov/Wps/portal/nres/detail/national/soils/?
cid=n res 142p2_053624
United States Department of Agriculture, Soil Conservation Service. 1961. Land
capability classification. U.S. Department of Agriculture Handbook 210. hffp://
www.nrcs.usda.gov/lnternet/FSE—DOCUMENTS/nrcsl42p2_052290.pdf
17 Page 78 of 78