HomeMy WebLinkAboutWPO201700040 Calculations 2017-08-23PROJECT MANAGEMENT
SHIMPCIVIL ENGINEERING
LAND PLANNING
ENGI N EERI NGa
August 23, 2017
County of Albemarle
Department of Community Development
401 McIntire Road
Charlottesville, VA 22902
Regarding: Kapp Driveway
Stormwater Management Plan
Dear Reviewer,
The purpose of construction is to build a driveway from TMP 984C to TMP 98-14 that crosses a stream.
The total area of disturbance, which is the limit of analysis, is 3.269 acres.
Water quality standards set forth by 9VAC-25-870-65 will be satisfied with the purchase of nutrient credits
in the amount of 1.72 Ibs/yr.
This site is not subject to energy balance analysis, as all runoff is discharged as sheet flow through the use
of level spreaders. The site meets the flood protection requirements set forth in 9VAC25-870-66 subsection
C, because all runoff is discharged into an existing floodplain.
All stormwater calculations have been included in this report.
Contents:
Land Use:
Pre -Development Land Use Map
Post -Development Land Use Map
Stormwater Quality Calculations:
VRRM New Development Spreadsheet
Culvert Sizing Calculations:
Culvert Sizing Drainage Map
LD-229 Storm Drain Calculations
Independent Reports:
Excerpt from NRCS Soils Report
NOAA Precipitation Report
Land Use
Pre -Development Land Use Map
Post -Development Land Use Map
Pre Development
/ - SWM Map
/ i
Kapp Driveway
-(�__Oz z Z
HSG B
/ / / / /V OPEN SPACE
/ // / / / Total 0.66 acres
/ / /
/ / /
MANAGED TURF
/ / ) Total 0.00 acres
/ r
IMPERVIOUS
Total 0.00 acres
0 IV
r
�0007/// /
/
------ -------- ----
- /
/ A& 1
50 0 50 100 150
Scale: 1 "=50'
Page 1
Pre Development
SWM Map
■ / / / � / / / / Kapp Driveway
HSG B
IV OPEN SPACE
Total 1.48 acres
MANAGED TURF
Total 0.00 acres
/
IMPERVIOUS
I / I Total 0.00 acres
40'
40'
40
I
I I / / 41*�
50 0 50 100 150
Scale: 1 "=50'
Page 2
Pre Development
SWM Map
Kapp Driveway
` I I HSG B
-
OPEN SPACE
Total 1.12 acres
\ Z e
-
■ MANAGED TURF
Total 0.00 acres
I
IMPERVIOUS
Total 0.01 acres
X
I Nor
0
\44% **4
i /
50 150
Scale: 1 "=50'
Page 3
Post Development
// / - SWM Map
/ i
/ / / / Kapp Driveway
\ \� Z / / / HSG B
50 0 50 100 150
Scale: 1 "=50'
Page 1
Post Development
SWM Map
Kapp Driveway
HSG B
■ / / / / / / ,V OPEN SPACE
Total 0.00 acres
F
MANAGED TURF
Total 1.13 acres
F IMPERVIOUS
15 ' I Total 0.35 acres
40'
4e
mom EIF EE F� I woo
-
6
--F 1001� E 6 E E E
� YYY
N
E � � � � E � E F � F E E E E ■
40'/
E
f E
6 F 6 F F F < F F \ F F F
f E E E� E
F E E F V• F 6 F �E —
FF FFF*40* I 00,0 F F FF� �FFFF�
woo E 1 F' F F ow
F 6 6 E T E E E
F E
I
■
NOW
50 0 50 100 150
Scale: 1 "=50'
Page 2
Post Development
SWM Map
Kapp Driveway
F
F
F/0,00I I i
♦ FFEF��
� FFE FE1 I I l
E E E
■4** F F FF F F F F FF F FF F \ HSGB
OPEN SPACE
F F F F F F F� F / I I Total 0.00 acres
15
I I I
Z
� I I
F
♦� �� F F F F F � � � I I I �
■ `F F 1F sow
/
/ I I MANAGED TURF
■ F _ / I I I Total 0.85 acres
IMPERVIOUS
F F I Total 0.28 acres
Mina
soft
< Now ;<OWN nNo 000
ftft
I
E
� F
F IF 6 k � F 1 WOW�
F� I
E � f
F 0 I - F
goo
F F F F F F F
50 0 50 100 150
Scale: 1 "=50'
Page 3
Stormwater Quality Calculations
VRRM New Development Spreadsheet
Project Name: Kapp Driveway
Date: 13-Feb-17
BMP Design specifications List: 2013 Draft Stds & Specs
Site Information
Post -Development Project (Treatment Volume and Loads)
Land Cover (acres)
ASoils
BSoils
CSoils
DSoils
Totals
Forest/Open Space (acres) -- undisturbed,
protected forest/open spacereforested land
0.00
Managed Turf(acres)- disturbed, graded for
2.35
yards or other turf to be mowed/managed
2.35
Impervious Cover (acres)
0.92
0.92
3.27
Constants
Annual Rainfall (inches) 43
Target Rainfall Event (inches) 1.00
Total Phosphorus (TP) EMC(mg/L) 0.26
Total Nitrogen (TN) EMC(mg(L) 1.86
Target TP Load (lb/acre/yr) 0.41
Pj(unitless correction factor) 0.90
Runoff rnaffiriantc IR,i
CLEAR ALL
(Ctrl+Shift+R)
final results
ASoils
BSoils
CSoils
DSoils
Forest/Open Space
1 0.02
0.03
1 0.04
0.05
Managed Turf
1 0.15
0.20
1 0.22
0.25
Impervious Cover
1 0.95
0.95
1 0.95
0.95
TP Load Reduction
Required (lb/yr) 1 1.72
LAND
Land Cover Summary
COVER SUMMARY
0.00
0.00
0%
2.35
0.20
72%
0.92
0.95
28%
3.27
0.41
POSTDEVELOPMENT
Treatment Volume and Ni
Treatment Volume
(acre-ft)
Treatment Volume (cubic feet)
TP Load (lb/yr)
TN Load
Purposes
Informat'onalPu o es Onl
Forest/Open Space Cover (acres)
Weighted Rv(forest)
% Forest
Managed Turf Cover (acres)
Weighted Rv(turf)
%Managed Turf
Impervious Cover (acres)
Rv(impervious)
%Impervious
Site Area (acres)
Site Rv
0.1117
Site Results (Water Quality Compliance)
Area Checks
FOREST/OPEN SPACE (ac)
IMPERVIOUS COVER (ac)
IMPERVIOUS COVER TREATED (ac)
MANAGED TURF AREA (ac)
MANAGED TURF AREA TREATED (ac)
AREA CHECK
0.00
0.00
0.00
0.00T00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
OK.
OK.
OK.
OK.
OK.
AREA CHECK
OK.
Site Treatment Volume (ft;) 0°
Runoff Reduction Volume and TP By Drainage Area
D.A. C D.A. D D.A. E TOTAL
RUNOFF REDUCTION VOLUME ACHIEVED (k') 0 0 0 0 0 0
TP LOAD AVAILABLE FOR REMOVAL (Ib/yr) 0.00 0.00 0.00 0.00 0.00 0.00
TP LOAD REDUCTION ACHIEVED (Ib/yr) 0.00 0.00 0.00 0.00 0.00 0.00
TP LOAD REMAINING (Ib/yr) 0.00 0.00 0.00 0.00 0.00 0.00
NITROGEN LOAD REDUCTION ACHIEVED (Ib/yr) 0.00 0.00 0.00 0.00 0.00 0.00
Total Phosphorus
FINAL POST -DEVELOPMENT TP LOAD (Ib/yr) 3.06
TP LOAD REDUCTION REQUIRED (Ib/yr) 1.72
TP LOAD REDUCTION ACHIEVED (Ib/yr) 0.00
TP LOAD REMAINING (Ib/yr): 3.06
REMAINING TP LOAD REDUCTION REQUIRED (Ib/yr): 1.72
Total Nitrogen (For Information Purposes)
POST -DEVELOPMENT LOAD (Ib/yr) 21.88
NITROGEN LOAD REDUCTION ACHIEVED (Ib/yr) 0.00
Virginia Runoff Reduction Method Worksheet
DEQ Virginia Runoff Reduction Method New Development Compliance Spreadsheet - Version 3.0
BMP Design Specifications List: 2013 Draft Stds 8, Specs
Site Summary
Total Rainfall = 43 inches
Site Land Cover Summary
A soils
B Soils
C Soils
D Soils
Totals
% of Total
Forest/Open (acres)
0.00
0.00
0.00
0.00
0.00
0
Managed Turf (acres)
0.00
2.35
0.00
0.00
2.35
72
Impervious Cover (acres)
0.00
0.92
0.00
0.00
0.92
28
3.27
100
Site Tv and Land Cover Nutrient Loads
Site Rv
0.41
Treatment Volume (ft)
4,867
TP Load (lb/yr)
3.06
TN Load (lb/yr)
21.88
Total TP Load Reduction Required (lb/yr) 1.72
Site Compliance Summary
Total Runoff Volume Reduction (ft)
0
Total TP Load Reduction Achieved (lb/yr)
0.00
Total TN Load Reduction Achieved (lb/yr)
0.00
Remaining Post Development TP Load
3.06
(lb/yr)
Remaining TP Load Reduction (lb/yr)
1.72
Required
Summary Print
Culvert Sizing Calculations
Culvert Sizing Drainage Map
LD-229 Storm Drain Calculations
LD-229 Storm Drain Design Computations
Kapp Drivewav
From
Point
To Point
Catch
A
(ac)
Runoff
Coef
Inc
AC
Accum
AC
Tot
Tc
(min)
Tot
Int (10yr)
(in/hr)
Tot
Flow (10yr)
(cfs)
Up
Inv
El
Dn
Inv
El
Pipe
Len
(ft)
Inv
S
%
Pipe
Dim
(in)
Pipe
Cap
(cfs)
Velocity
(ft/s)
Flow time
Inc
(min)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Al
A2
0.07
0.08
0.01
0.01
5.00
7.01
0.04
860.00
858.50
39
4%
15
17
4.6
0.14
B1
B2
1 0.33
0.09
1 0.03
0.03
1 5.00
7.01
1 0.21
773.00
1 772.00
25
1 4%
15
1 17
4.7
0.09
Independent Reports
Excerpt from NRCS Soils Report
NOAA Precipitation Report
3
a"
37' 57 21" N
I
v
8
e
I
37' 56' 51" N
Custom Soil Resource Report
Soil Map
7034M 703500 703600 7W700
703400 703500 703600 703700 703800 703900
3
a Map Scale: 1:4,550 W printed on A portrait (8.5" x 11") sheet
� N Meters
0 50 100 200 300
Feet
0 200 400 800 1200
Map projection: Web Mercator comer coordinates: WGS84 Edge tics: UTM Zone 17N WGS84
6
3
a"
70CM
37° 57 21" N
I
v
I
I
1
37° 56 51" N
704000
3
MAP LEGEND
Area of Interest (AOI)
0
Area of Interest (AOI)
Soils
0
Soil Map Unit Polygons
im 0
Soil Map Unit Lines
■
Soil Map Unit Points
Special
Point Features
Blowout
Borrow Pit
Clay Spot
Closed Depression
Gravel Pit
.4
Gravelly Spot
0
Landfill
Lava Flow
Marsh or swamp
+
Mine or Quarry
Miscellaneous Water
Perennial Water
Rock Outcrop
Saline Spot
Sandy Spot
Severely Eroded Spot
Sinkhole
Slide or Slip
oa
Sodic Spot
Custom Soil Resource Report
MAP INFORMATION
A
Spoil Area
The soil surveys that comprise your AOI were mapped at
1:15,800.
Stony Spot
Very Stony Spot
Warning: Soil Map may not be valid at this scale.
Wet Spot
Enlargement of maps beyond the scale of mapping can cause
Other
misunderstanding of the detail of mapping and accuracy of soil
.-
Special Line Features
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
Water Features
scale.
-
Streams and Canals
Transportation
Please rely on the bar scale on each map sheet for map
�}}
Rails
measurements.
Interstate Highways
Source of Map: Natural Resources Conservation Service
US Routes
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Major Roads
Local Roads
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
Background
distance and area. A projection that preserves area, such as the
Aerial Photography
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 10, Dec 11, 2013
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: May 10, 2010—Jul 4,
2010
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.
7
Custom Soil Resource Report
Map Unit Legend
Albemarle County, Virginia (VA003)
Map Unit Symbol
Map Unit Name
Acres in AOI
Percent of AOI
7B
Braddock loam, 2 to 7 percent
7.2
9.1 %
slopes
7C
Braddock loam, 7 to 15 percent
8.8
11.1 %
slopes
0.8
1.0%
8C3
Braddock clay loam, 7 to 15
percent slopes, severely
eroded
9B
Braddock very stony loam, 2 to
5.2
6.6%
7 percent slopes
0.1
14D
Chester loam, 15 to 25 percent
0.1 %
slopes
19B
Cullen loam, 2 to 7 percent
0.3
0.3%
slopes
19C
Cullen loam, 7 to 15 percent
0.1
0.1 %
slopes
25B
Dyke silt loam, 2 to 7 percent
2.9
3.7%
slopes
25C
Dyke silt loam, 7 to 15 percent
13.7
17.4%
slopes
36B
Hayesville loam, 2 to 7 percent
5.8
7.4%
slopes
36C
Hayesville loam, 7 to 15 percent
6.9
8.8%
slopes
37D3
Hayesville clay loam, 15 to 25
7.4
9.4%
percent slopes, severely
eroded
77
Rive rview-Chewacla complex
10.6
13.4%
79B
Starr silt loam, 2 to 7 percent
9.2
11.7%
slopes
79.0
100.0%
Totals for Area of Interest
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
0
2/10/2017 Precipitation Frequency Data Server
NOAA Atlas 14, Volume 2, Version 3
Location name: North Garden, Virginia, USA* � ,b,
Latitude: 37.9553°, Longitude:-78.6814°
Elevation: 867.12 ft** t
source: ESRI Maps k �+
** 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)1
Duration
Average
recurrence interval (years)
1
��������F�
2
5 10
25
50
100
200
500
1000
0.343
0.408
0.479 0.542
0.611
0.665
0.716
0.763
0.820
0.866
5-min
(0.310-0.379)
(0.369-0.451)
(0.434-0.530) (0.489-0.598)
(0.548-0.673)
(0.594-0.732)
(0.635-0.789)
(0.672-0.843)
(0.713-0.909)
(0.746-0.966)
0.547
0.652 IF
0.768 0.866
0.974
1.06
1.14
1.21
1.30
1.36
10�rtin
(0.495-0.606)
(0.591-0.722)
(0.694-0.848) (0.781-0.956)
(0.874-1.07)
(0.945-1.17)
1 (1.01-1.25)
1 (1.06-1.34)
1 (1.13-1.44)
1 (1.17-1.52)
0.684
0.820 IF
0.971 1.10
1.24
1.34
1 A4 IF
1.53
1.63 IF
1.71
15�rtin
(0.618-0.757)
(0.743-0.908)
(0.878-1.07) (0.988-1.21)
1 (1.11-1.36) 11
(1.20-1.48)
1 (1.27-1.58)
1 (1.34-1.69)
1 (1.42-1.81)
1 (1.47-1.91)
0.938
1.13
1.38 1.59
1.83
2.02
2.20 IF
2.38
2.60 IF
2.77
30�nin
(0.848-1.04)
1 (1.03-1.25)
1 (1.25-1.52) (1.43-1.75)
1 (1.64-2.01)
1 (1.80-2.22)
1 (1.95-2.43)
1 (2.09-2.63)
1 (2.26-2.88)
1 (2.39-3.09)
1.17
1.42
1.77 2.07
2.44
2.74
3.03
3.33
3.73
4.05
60�rtin
(1.06-1.29)
1 (1.29-1.57)
1 (1.60-1.95) (1.86-2.28)
1 (2.19-2.68)
1 (2.44-3.01)
1 (2.69-3.34)
1 (2.93-3.68)
1 (3.24-4.13)
1 (3.48-4.51)
1.40
1.70
2.13 2.51
2.98
3.39
3.80
4.22
4.80
5.29
2-hr
(1.25-1.57)
1 (1.51-1.91)
1 (1.90-2.39) (2.23-2.81)
1 (2.64-3.34)
1 (2.98-3.79)
1 (3.31-4.25)
1 (3.65-4.73)
1 (4.10-5.40)
1 (4.47-5.97)
1.53
1.86
2.33 2.74
3.27
3.71
4.17
4.64
5.29
5.85
3-hr
(1 .37-1.74)
(1.65-2.10)
(2.06-2.63) (2.42-3.09)
(2.88-3.68)
(3.25-4.18)
(3.62-4.70)
(4.00-5.24)
(4.49-5.99)
1 (4.91-6.64)
1.99
2.41
2.99 3.52
4.86
4.23
5.51 IF
6.21
7.21 IF
8.10
6-hr
(1.78-2.25)
1 (2.15-2.71)
1 (2.65-3.36) (3.12-3.97)
(3.72-4.76) 11
(4.24-5.45)
(4.76-6.19)
1 (5.30-7.00)
(6.05-8.15)
1 (6.69-9.18)
2.53
3.06
3.80 4.51
5.49
6.36
7.31
8.35
9.88
11.3
12�tr
(2.26-2.89)
1 (2.72-3.48)
1 (3.37-4.32) (3.98-5.12)
1 (4.80-6.21)
1 (5.50-7.20)
1 (6.24-8.28)
1 (7.02-9.46)
1 (8.13-11.2)
1 (9.11-12.9)
3.07
3.72
4.75 5.61
6.88
7.96
9.16
10.5
12.4
14.1
24�r
(2.76-3.45)
1 (3.34-4.17)
1 (4.25-5.32) 1 (5.00-6.27)
1 (6.09-7.67)
1 (7.01-8.88)
1 (7.99-10.2)
1 (9.05-11.6)
1 (10.6-13.8)
1 (11.8-15.7)
2tlay
(3.26 4?04)
(3.95 4990)
(5.01 6522)
(5.87575.30)
(7. 898.85)
(8.071 0.2)
(9.1-141.6)
(1 3 3.1)
(11 9-15.4)
(13.12-157.4)
3.86
4.67
5.93
6.96
8.45
9.69
11.0
12.5
14.6
16.4
3tlay
(3.49-4.29)
1 (4.23-5.19)
1 (5.36-6.58) 11
(6.27-7.72)
1 (7.57-9.36)
1 (8.63-10.7)
1 (9.75-12.2)
1 (10.9-13.8)
1 (12.7-16.2)
1 (14.0-18.3)
4.09
4.96
6.28
7.37
8.93
10.2
11.6
13.2
15.4
17.3
4�lay
(3.73-4.53)
(4.51-5.48)
(5.71-6.95)
(6.68-8.13)
(8.06-9.86)
(9.18-11.3)
(10.4-12.9)
(11.6-14.5)
14.4
(13.4-17.0)
(14.9-19.1)
4.75
5.72
7.14
8.30
9.96
11.3
12.8
16.6
18.5
7tlay
(4 .35-5.20)
(5.24-6.26)
(6.53-7.82)
(7.58-9.08)
(9.04-10.9)
(10.2-12.4)
(11.5-14.0)
(12.8-15.7)
(14.6-18.3)
(16.1-20.4)
15.2
5.39
6.46 IF
7.97
9.18
10.9 IF
12.3
13.7
17.4 IF
19.1
10-day
(4.96-5.85)
(5.95-7.02)
1 (7.33-8.65)
(8.42-9.96)
(9.93-11.8)
(11.1-13.3)
(12.4-14.9)
(13.7-16.5)
(15.4-18.9)
(16.8-20.9)
756
8.42
10.2
11.5
13.4
14.8
16.3
17.8
19.8
21.4
20-day
(6.58-7.60)
(7.85-9.06)
(9.46-10.9)
(10.7-12.4)
(12.4-14.4)
(13.7-15.9)
(15.0-17.5)
(16.3-19.2)
(18.0-21.5)
(19.3-23.3)
16.8
8.67
10.3
12.1
13.6
15.4
18.2
19.5
21.3
22.6
30-day
(8.13-9.26)
(9.63-11.0)
(11.4-13.0)
(12.7-14.5)
(14.4-16.5)
(15.6-18.0)
(16.9-19.4)
(18.1-20.9)
(19.6-22.9)
(20.7-24.4)
20.1
10.8
12.8
14.9
16.5
18.5
21.5 IF
22.9
24.7 IF
26.1
45-day
(10.2-11.5)
1 (12.0-13.6)
1 (14.0-15.8) 11
(15.5-17.5)
(17.4-19.7)
1 (18.8-21.3)
(20.1-22.9)
1 (21.3-24.4)
(22.9-26.4)
1 (24.1-27.9)
22.6
12.7
14.9
17.2
18.9
21.1
24.1
25.5
27.3
28.6
60-day
(12.0-13.4)
(14.1-15.8)
(16.3-18.2)
(17.8-20.0)
(19.8-22.2)
(21.3-23.9)
(22.6-25.5)
(23.9-27.0)
(25.5-29.0)
(26.6 30.4)
Precipitation frequency (PF) estimates in this table are 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 precipitation frequency estimates (for a
given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not
checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values.
Please refer to NOAA Atlas 14 document for more information.
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