HomeMy WebLinkAboutWPO202000010 Calculations 2020-06-08SHIM P ENGINEERING, P.C.
Design Focused Engineering
Stormwater Management Plan
Calculation Packet
Stoudt Property
May 7, 2020
Revised: June 4, 2020
SHIMP ENGINEERING, P.C.
Design Focused Engineering
June 4th, 2020
Emily Cox
Albemarle County
Po. Box 160
Louisa, VA 23093
Regarding: WPO202000010 Stoudt Property
Stormwater Management Plan
Dear Ms. Cox,
Enclosed is the stormwater management calculations for the Stoudt Property Project. This project will
disturbed an area of 0.99 acres.
This project complies with the water quantity requirements of 9VAC25-870-66.D for increased volumes of
sheetflow. The runoff from the new impervious areas will be in sheetflow condition. Runoff from the new
impervious areas maintain sheetflow into a vegetated landscaping strip that aids in slowing the sheetflow,
allowing for infiltration to occur. Downstream properties and resources have been evaluated and it was
determined that the existing manner of sheetflow to the existing property will not change and the minor
increase in volume does not cause concern for down -gradient erosion, sedimentation, or flooding.
This site complies with the water quality requirements of 9VAC25-870-65 by purchasing nutrient credits as
required by the VRRM Re -Development Spreadsheet. The total phosphorus Load Reduction Required is
0.25 Ibslyr. To achieve this reduction 0.25 nutrient credits shall be purchased. Thus, satisfying the VRRM
Water Quality Requirements of 9VAC25-870-65.
If you have any questions please feel free to contact me via e-mail at michael@shimp-engineering.com or
Justin Shimp at justin@shimp-engineering.com or by telephone at 434-227-5140.
Sincerely,
Justin Shimp
Shimp Engineering, P.C.
Contents:
Stormwater Quality Calculations:
Pre -Development VRRM Map
Post -Development VRRM Map
VRRM Spreadsheet
Independent Reports:
Excerpt from NRCS Soils Report
NOAA Precipitation Report
Stormwater Quality Calculations:
Pre -Development VRRM Map
Post -Development VRRM Map
VRRM Spreadsheet
Nutrient Credit Availability
SIIII7PPNGA RA6. P. C.
HSG ENGINEERING IANDPLANNING PROJECT MANAGEMENT
4
912 E HIGH ST PHONE: (434) 227-5140
CHARLOTTESVILLE, VA 22902 JUSTIN®SHIMP-ENGINEERING.COM
LEGEND
TURF MANAGED AREA
i4\\\ LIMITS OF DISTURBANCE
Ira`,
�8SOI LS (TYF) \
1 f / HSGB \� \
EXISTING �.\ �\ �`�� �� `-----''� � � \
488,
00
AME BA
_¢90
> \
1000
/co_ — _ \
o`er
/
MANAGED TURF LI M ITS OF '-495
DISTURBANCE ,---- 96
l i `4g7 \--- - `\ \\ F \ \ 1 \
0.99 AC EXISTING' �G'F \\ \ 1 \\
�/_ _ 4�71 R9DAE �AG \\
FFE=498.0 \\\\ \---' ,�--g9>�___
8 \\\ \\ \ 1 P
_480-
HSG B
FX. 2 STORY FRN E
-CS cO �'' \\\ $ -- - - HOUSE W/ BASE T
wl I i /'� FEE=
494
I 1 el
HSGB Lithic Stoudt Handy
I HSGB
\ ¢9'''-------- (' Pre -Development VKKM Map
1 REVISED: 05- 1 2-2020
-----_ -494-
\. \
• 1 • • i• _•
SCALE: 1 •
Pre -Re Development Land Cover (acres)
A Soils
B Soils
C Soils
D Soils
L Totals
Forest/Open Space (acres) -- undisturbed
forest/open sace
0.00
(Managed Turf ( acres) -- disturbed, graded
for yards or otherturf to be
0.99
0.99
Impervious Cover (acres)
000
0.00
0.99
SIIIMPEYNY PRING, P. C.
_ _ ENGINEERING-L 4YDPL4WNG -PROJECT MANAGEMENT
I HSG/$ / , / — - _,
'/�_���� 912 E HIGH ST PHONE: (434) 227-5140
CHARLOTTESVILLE. VA 22902 JUSTIN®SHIMP-ENGINEERING.COM
LEGEND
TURF MANAGED AREA
LIMITS OF DISTURBANCE
I �0 /.
HSG
I
/ i I
/ / I
/ / O
/
/
' o
— -480- /
SWIMMING POOL DOES
NOT OUTLET Off51TE.
NOT CONSIDERED
IMPERVIOUS IN VRRM
5FREAD5MEET
HSG B
\ ❑ IMPERVIOUS AREA
�\
�— _
' �1148S` ��� ;_ 501 Ls (TYP)
EXISTING N` ��\
--- -
�491 \ �,488` \\ \IN
\
-490�
93
LIMITS OF
DISTURBANCE
-9 `49 - \
��_---------496\ ��
1 - EXISTING �� �� _�' 10cF
'IMPERVOUs 1.5 STA�j-Y-
R gM I r AG \\
FFE=498.0
/ -- g8 \ 1
—• �� I i / `\ ---- - ,� y/- ` HSG I
a, E�X: 2 STORY FIRE
HOUSE W/ BASE T\
/�•�'' �i� FEE= -' `---98,�
499 Lithic 5toudt Handy
i I � I J'
Post -Development VKKM Map
l HSGB / r r�¢9j / HSGB �_ <
/ , �\ �g) ,,; REV15ED: 05- 1 2-2020
If----- tr ;
50 0 50 100 A 150
SCALE: 1 "=50'
NI /N
N 149, 11 _
-------------496----.�o,`�
Post -Development Land Cover (acres)
ASoils
BSoils
CSoils
DSoils
Totals
Forest/Ope n Space (acres) -- and isturbe d,
rotectedforest/o ens ace or reforested
0.00
Managed Turf ( acres) -- di stu rbe d, graded
for yards or other turf to be
0.87
D.87
Impervious Cover (acres)
0.12
0.12
Area Check
OK.
OK.
OK.
OK.
0.99
DEQ Virginia RunofJReduction Method Re -Development Compliance Spreadsheet - Version 3.0
132011 BMP Standards and Specifications 0 2013 Draft BMP Standards and Specifications
Project Name: Lithic Staudt Handy dad.... put cells
..® Date: 6/4/2020 values
.........................................................
c
Linear Development Project? No calculation cells
Site Information
Post -Development Project (Treatment Volume and Loads)
Enter Total Disturbed Area (acres) 4 0.99 Check:
BMP Design Speciffmtions List. 2013 Draft Stds & Specs
Maximum reduction required� rproject? No
The site's net increase in impervious cover (acres)IS. Land cover areas entered
ed correctly? ✓
Post -Development TP Load Reduction for Site (Iblyr):® Total disturbed area entered? ✓
Pen spec or reforested land
om
O.BJ
0.12
OK. 0.99
Rv
Asoils Bswls esoils DSoils
0.02 0.03 0.04 0.05
0.15 0.20 0.22 0.25
0.95 0.95 0.95 0.95
"I disturbed, graded for
to be mowed/managed
O.BJ
(acresl
0.12
Area Check OK.
OK.
OIL
Runoff Coefficients
:hes)
43
nt lin<hesl
1.00
Forest/Open Spa<e
ITP)EMC(mg/L)
0.26
Managed Turt
I EMC Img/Ll
1.86
Impervlous Cover
Pre-ReDvvelppment
Listed
Adjusted'
Past ReDev. & N.Impervious
Post-ReDevelapmem
For /Open space
CaverO-)
000
Post -Development New Impervious
Forest/Open Space Cover (acresl
0.00
0.00
Forest/Open Space
Cover lacres)
000
New Impervlous Cover 0,12
(acres)
Weighted RNforest)
0.00
D00
Weight.d Rvlfores[l
0.00
Weighted RvRoresq
%Forest
am
0%
%Forest
0%
0%
%Forest
0%
Managed Turf Cover (acresl
0.99
D87
ManagledacresTurfove Cr
)
087
Managelacd Cover
res) Turf
087
Weighted RvRurt)
0.20
0.20
Weighted Rv(In i)
0.20
Weighted Rv (turt)
0.20
100%
000
%Managed Turf
100%
10096
%Managed Turf
88%
%Managed Tuff
ReDev.lmpervlous
cover(acres)
Impervious Cover(acres)
0.00
0.00
Impervious Cover lacres)
0.12
Fb,dn, rviousl
D95
D95
Rvlimpervious)L!2%'
Rv(impervious)0.95%Impervious
%Impervious
0%Total
0%
0%
%Impervious
site Area laves)
0.99
0.8]
Final Site Are.(.aea)
Total Re -Ste Area
(aaes)site
09T
Rv
0.20
0.20
Final Post Dev site Rv
RIM, Site Rv
0.10
Treatment Volume and
Nutrient Load
Final Post -Development
m volume
mlave-XI
0,0240
Treatment Volume and
Post-ReDevelopment
T mein Volume
reat(a<re-ft)
Nutrient Load
0,0145
Post -Development
T m volume 0.0095
atlave-XI
Pre ReDevelopment Treatment Volume
lave-X)
0.0165
0.0145
Final Post -Development
Treatment Volume
1,045
Post-ReDvvelgpment
Treatment Valume
Post-Developmem
Treatment Volume(abic /14
Pre-ReDevelapmen[Treatment Volume
219
632
(abl<lem)
(cublcfee0
Final Post-
Development TP Laad
0.66
(abI<fem)
P.111Development
bad ITN
0
feed
Post-DevelopmemlP
0.26
Pre-ReDevelOpment lP Load
0.45
0.40
(Ib/yd
(lb/yr)
fa�eal TP
D�a
(Ib/Yr)*
men9b/a<re/yrlas
Iro/«re/vrl
Rlne
Lwd(Ib/Yr)
are-Repevelopmen[m batl pera<re
g.4s
Baseline TP Load (lb/yr)
(0.41 in/a<re/yra Plietlm p e-retleve
pnposetl for newmpe mmcover)
--ding pe io
0.36
- a4%
Dev p a[ ael
TP Load Reduction
TP Load Reduction
Aduscedtondcoversummory:
re ne-elopment bM rover in. pervious land cover(farest/open
spare ar managed
Requiretl for
004
Required for New 0.21
.,f) avegge proposedfor newimperviouscover.
Md.veloped Area
Impervious Area Ob/yrl
(lb/yr)
id/usted[otala<reogeis[onsistent wRh Pos[-FeOevelopmen[a<reoge (minus o[reage
fne impervious coved.
31 I shows land reduction nqudement far new
Impervious rover
(based on clew
ievelnpment load b-, D.4] Ibs/o[re/yeor).
TP Load Reduction Required (lb/yr) I 0.25
Nitrogen Loads (Informational Purposes Only)
Final Port -Development TN Load
re-Re0evelopmen[TN Load pb/yr) 3.23 (Post-ReDevelopment&New lmpervlousl 4.J0
(lb/yr)
Virginia Runoff Reduction Method Worksheet
DEQ Virginia Runoff Reduction Method Re -Development Compliance Spreadsheet - Version 3.0
BMP Design Specifications List: 2013 Draft Stds & Specs
Site Summary
Project Title: Lithic Staudt Handy
Date: 43986 Total Rainfall (in): 43
Total Disturbed Acreage: 0.99
Site Land Cover Summary
Pre-ReDevelopment Land Cover (acres)
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
0.99
0.00
0.00
0.99
100
Impervious Cover (acres)
0.00
0.00
0.00
0.00
0.00
0
0.99
100
Post-ReDevelopment Land Cover (acres)
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
0.87
0.00
0.00
0.87
88
Impervious Cover (acres)
0.00
0.12
0.00
0.00
0.12
12
0.99
100
Site Tv and Land Cover Nutrient Loads
Final Post -Development
Post
Post-
Adjusted Pre-
(Post-ReDevelopment
ReDevelopment
Development
ReDevelopment
& New Im
Impervious)
p )
(New Impervious)
Site Rv
0.29
0.20
0.95
0.20
Treatment Volume (ft)
1,045
632
414
632
TP Load (lb/yr)
1 0.66
0.40
0.26
0.40
Total TP Load Reduction Required (lb/yr) 0.25 0.04 0.21
Final Post -Development Load
(Post-ReDevelopment & New Impervious)
Pre-
ReDevelopment
TN Load (lb/yr)
4.70
3.23
Pre-
ReDevelopment
Final Post -Development
Post-ReDevelopment TP
TP Load per acre
TP Load per acre
Load per acre
(lb/acre/yr)
(lb/acre/yr)
(lb/acre/yr)
0.46
0.66
0.46
Summary Print
Virginia Runoff Reduction Method Worksheet
Site Compliance Summary
Maximum % Reduction Required Below 10%
Pre-ReDevelopment Load
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
(lb/yr)
0.66
Remaining TP Load Reduction (lb/yr)
Required
0.25
Summary Print
Virginia Runoff Reduction Method Worksheet
Drainage Area Summary
D.A. A
D.A. 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)
0.00
0.00
0.00
0.00
0.00
0.00
Impervious Cover (acres)
0.00
0.00
0.00
0.00
0.00
0.00
Total Area (acres)
0.00
0.00
0.00
0.00
0.00
0.00
Drainage Area Compliance Summary
D.A. A
D.A. B
D.A. C
D.A. D
D.A. E
Total
TP Load Reduced (lb/yr)
0.00
0.00
0.00
0.00
0.00
0.00
TN Load Reduced (lb/yr)
0.00
0.00
0.00
0.00
0.00
0.00
Summary Print
Virginia Runoff Reduction Method Worksheet
Runoff Volume and CN Calculations
I 11-year storm 1 2-year storm ) 10-yearstorm I
(Target Rainfall Event (in) 1 0.00 1 0.00 1 0.00 1
Drainage Areas
RV & CN
Drainage Area A
Drainage Area B
Drainage Area C
Drainage Area D
Drainage Area E
CN
0
0
0
0
0
RR (ft3)
0
0
0
0
0
1-year return period
RV wo RR (ws-in)
0.00
0.00
0.00
0.00
0.00
RVwRR(ws-in)
0.00
0.00
0.00
0.00
0.00
CN adjusted
0
0
0
0
0
2-year return period
RV wo RR (ws-in)
0.00
0.00
0.00
0.00
0.00
RVwRR(ws-in)
0.00
0.00
0.00
0.00
0.00
CN adjusted
0
0
0
0
0
10-year return period
RV wo RR (ws-in)
0.00
0.00
0.00
0.00
0.00
RV w RR (ws-in)
0.00
0.00
0.00
0.00
0.00
CN adjusted
0
0
0
0
0
Summary Print
Rivanna River Nutrient Bank
June 4, 2020
MICHAEL CHANDLER
Project Engineer
Michael@Shimp-Engineering.com
Shimp Engineering, P.C.
912 East High St. Charlottesville, VA 22902
Owner: Alice & Peter Stoudt
Contact: Michael Chandler
Project Name and Number: Stoudt Property #: 20.003
Location: 2278 Chapel Spring Rd. Free Union, VA 22940
Legal Ref: DB 3841 P 520.
Credits Req.:.25
Project HUC: 02080204
Coordinates: 38.175428,-78.580204
Dear Michael,
Certificate No. James-039
This letter is to confirm the availability of authorized Nutrient Credits sufficient to meet your
projects requirements of .25 lbs. Nutrient Credits at our above referenced nutrient offset credit
bank facility (the "Bank"), which is registered with the Virginia Department of Environmental
Quality (DEQ). These Nutrient Credits are generated and managed under the terms of the
Reduction Implementation Plan for the Bank dated November 2017, which was authorized by the
Virginia Department of Environmental Quality (DEQ) on September 5, 2018.
The Bank has been authorized to provide Nutrient Credits for use in the James River watershed.
These credits are transferable to those entities regulated under DEQ's Storm Water Management
program in accordance with VA Code 62.1-44.15:27.
If we can provide further assistance please feel free to contact our office.
Hotel Street Ca ' , LLC, Bank Sponsor
By Its M/ �� -
Rivanna River Nutrient Offset Trading Bank, 31 Garrett Street, Warrenton, Virginia 20186
Independent Reports:
Excerpt from NRCS Soils Report
NOAA Precipitation Report
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
January 21, 2020
3
711840
38' 10' 41" N
I
I
v
e
38° 10' 26" N
711840 711890 711940 711990 712040
3
Map Scale: 1:2,180 W printed on A portrait (8.5" x 11") sheet.
Meters
N 0 30 60 120 180
Feet
0 100 200 400 600
Map projection: Web Mercator Comer coordinates: WGS84 Edge tics: UTM Zone 17N WGS84
9
Custom Soil Resource Report
Soil Map
711890 711940 711990 712040
712090
712090
3
s
712140
38° 10' 41" N
38° 10' 26" N
712140
3
Custom Soil Resource Report
Albemarle County, Virginia
4D—Ashe loam, 15 to 25 percent slopes
Map Unit Setting
National map unit symbol: kbcl
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
Ashe and similar soils: 80 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Ashe
Setting
Landform: Mountain slopes
Landform position (two-dimensional): Summit
Landform position (three-dimensional): Interfluve
Down -slope shape: Convex
Across -slope shape: Convex
Parent material: Residuum weathered from granite and gneiss
Typical profile
H1 - 0 to 10 inches: loam
H2 - 10 to 19 inches: loam
H3 - 19 to 24 inches: sandy loam
H4 - 24 to 79 inches: bedrock
Properties and qualities
Slope: 15 to 25 percent
Depth to restrictive feature: 20 to 40 inches to lithic bedrock
Natural drainage class: Somewhat excessively drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat): Very low to high (0.00
to 5.95 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Available water storage in profile: Low (about 3.2 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 6e
Hydrologic Soil Group: B
Hydric soil rating: No
13
Custom Soil Resource Report
713-13raddock loam, 2 to 7 percent slopes
Map Unit Setting
National map unit symbol: kbfb
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
Braddock and similar soils: 80 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Braddock
Setting
Landform: Fans
Landform position (three-dimensional): Tread
Down -slope shape: Convex
Across -slope shape: Linear
Parent material: Alluvium and colluvium derived from acid crystalline rocks
Typical profile
H1 - 0 to 8 inches: loam
H2 - 8 to 79 inches: clay
Properties and qualities
Slope: 2 to 7 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat): Moderately high to
high (0.57 to 1.98 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Available water storage in profile: High (about 9.1 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 2e
Hydrologic Soil Group: B
Hydric soil rating: No
14
Custom Soil Resource Report
7C—Braddock loam, 7 to 15 percent slopes
Map Unit Setting
National map unit symbol: kbfc
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
Braddock and similar soils: 80 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Braddock
Setting
Landform: Fans
Landform position (three-dimensional): Tread
Down -slope shape: Convex
Across -slope shape: Linear
Parent material: Alluvium and colluvium derived from acid crystalline rocks
Typical profile
H1 - 0 to 8 inches: loam
H2 - 8 to 79 inches: clay
Properties and qualities
Slope: 7 to 15 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat): Moderately high to
high (0.57 to 1.98 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Available water storage in profile: High (about 9.1 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 3e
Hydrologic Soil Group: B
Hydric soil rating: No
15
Custom Soil Resource Report
1913—Minnieville loam, 2 to 7 percent slopes
Map Unit Setting
National map unit symbol: 2v7hq
Elevation: 360 to 1,540 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
Minnieville and similar soils: 80 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Minnieville
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 acid and basic igneous rock
Typical profile
Ap - 0 to 8 inches: loam
Bt - 8 to 60 inches: clay
C - 60 to 67 inches: clay
Cr- 67 to 79 inches: bedrock
Properties and qualities
Slope: 2 to 7 percent
Depth to restrictive feature: 60 to 120 inches to paralithic bedrock
Natural drainage class: Well drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat): Very low to moderately
high (0.00 to 0.20 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Available water storage in profile: Moderate (about 7.6 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 2e
Hydrologic Soil Group: B
Hydric soil rating: No
16
Custom Soil Resource Report
81 B—Thurmont loam, 2 to 7 percent slopes
Map Unit Setting
National map unit symbol: kbfh
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
Thurmont and similar soils: 80 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Thurmont
Setting
Landform: I nterfluves
Landform position (two-dimensional): Summit
Landform position (three-dimensional): Interfluve
Down -slope shape: Convex
Across -slope shape: Convex
Parent material: Colluvium derived from granite, granodiorite, and granite gneiss
Typical profile
H1 - 0 to 10 inches: loam
H2 - 10 to 46 inches: clay loam
H3 - 46 to 56 inches: loam
H4 - 56 to 79 inches: cobbly sandy loam
Properties and qualities
Slope: 2 to 7 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat): Moderately high to
high (0.57 to 1.98 in/hr)
Depth to water table: About 48 to 79 inches
Frequency of flooding: None
Frequency of ponding: None
Available water storage in profile: Moderate (about 8.3 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 2e
Hydrologic Soil Group: B
Hydric soil rating: No
17
Custom Soil Resource Report
81 C—Thurmont loam, 7 to 15 percent slopes
Map Unit Setting
National map unit symbol: kbfj
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
Thurmont and similar soils: 80 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Thurmont
Setting
Landform: I nterfluves
Landform position (two-dimensional): Backslope
Landform position (three-dimensional): Interfluve
Down -slope shape: Convex
Across -slope shape: Convex
Parent material: Colluvium derived from granite, granodiorite, and granite gneiss
Typical profile
H1 - 0 to 10 inches: loam
H2 - 10 to 46 inches: clay loam
H3 - 46 to 56 inches: loam
H4 - 56 to 79 inches: cobbly sandy loam
Properties and qualities
Slope: 7 to 15 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Runoff class: Medium
Capacity of the most limiting layer to transmit water (Ksat): Moderately high to
high (0.57 to 1.98 in/hr)
Depth to water table: About 48 to 79 inches
Frequency of flooding: None
Frequency of ponding: None
Available water storage in profile: Moderate (about 8.3 inches)
Interpretive groups
Land capability classification (irrigated): None specified
Land capability classification (nonirrigated): 3e
Hydrologic Soil Group: B
Hydric soil rating: No
18
2/12/2020 Precipitation Frequency Data Server
NOAA Atlas 14, Volume 2, Version 3
Location name: Free Union, Virginia, USA*
Latitude: 38.1751*, Longitude:-78.58*
Elevation: 607.32 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)1
Average recurrence interval (years)
Duration
1 2 5 10 25 50 100 200 500 1000
����������
0.338
0.405 IF
0.478
0.539
0.610
0.666 IF
0.719 IF
0.770
0.834 IF
0.887
5-min
(0.306-0.374)
(0.367-0.448)
(0.432-0.528)
(0.486-0.596)
(0.547-0.673)
(0.593-0.733)
(0.636-0.793)
(0.676-0.850)
(0.723-0.925)
(0.761-0.987)
0.540
0.647
0.765
0.861
0.971
1.06
1.14
1.22
1.32
1.39
10-min
(0.489-0.597)
(0.586-0.716)
(0.691-0.845)
(0.776-0.951)
(0.870-1.07)
(0.943-1.17 )
( 1.01-1.26 )
( 1.07-1.35 )
( 1.14-1.46 )
( 1.20-1.55 )
0.674
0.813
0.967
1.09
1.23
1.34
1.44
1.54
1.66
1.75
15-min
(0.611-0.746)
(0.736-0.900)
(0.874-1.07)
(0.981-1.20)
(1.10-1.36)
1 (1.19-1.48)
1 (1.27-1.59)
1 (1.35-1.70)
1 (1.44-1.84)
1 (1.50-1.95)
0.923
1.12
1.37 1.58 1.82
2.01
2.20
2.39
2.63
2.83
30-min
(0.836-1.02)
1 (1.01-1.24)
1 (1.24-1.52) 1 (1.42-1.74) 11 (1.63-2.00)
1 (1.79-2.22)
1 (1.95-2.43)
1 (2.10-2.64)
1 (2.28-2.92)
1 (2.42-3.14)
1.15
1.41
1.76 2.05 2.42
2.73
3.03
3.35
3.78
4.12
60-min
(1.04-1.27)
1 (1.27-1.56)
1 (1.59-1.94) 1 (1.85-2.27) 11 (2.17-2.67)
1 (2.43-3.01)
1 (2.69-3.34)
1 (2.94-3.70)
1 (3.27-4.18)
1 (3.54-4.59)
1.38
1.68
2.11 2.48 2.96
3.37
3.79
4.23
4.86
5.39
2-hr
(1.23-1.55)
1 (1.50-1.88)
1 (1.88-2.36) 1 (2.21-2.77) 1 (2.62-3.31)
2.30 2.70 3.23
1 (2.96-3.76)
1 (3.31-4.23)
1 (3.67-4.73)
1 (4.16-5.45)
1 (4.56-6.07)
1.51
1.83
3.68
4.14
4.64
5.34
5.94
3-hr
(1.35-1.71)
1 (1.63-2.07)
1 (2.04-2.60) (2.39-3.04) 1 (2.84-3.63)
1 (3.21-4.13)
1 (3.60-4.66)
1 (3.99-5.23)
1 (4.54-6.03)
1 (4.99-6.73)
1.94
2.34
2.91 3.42 4.12
4.73
5.38
6.08
7.10
7.99
6-hr
(1.73-2.18)
(2.09-2.64)
(2.59-3.28) (3.03-3.85) 11 (3.62-4.63)
(4.13-5.31)
(4.64-6.04)
(5.19-6.84)
(5.96-8.01)
(6.61-9.05)
2.44
2.95
3.67
4.33 7F
5.27
6.11
7.02
8.04
9.55
10.9
12-hr
(2.17-2.77)
(2.62-3.34)
(3.25-4.17)
(3.83-4.92)
(4.62-5.97)
(5.29-6.91)
(6.00-7.95)
(6.77-9.10)
(7.88-10.9)
(8.85-12.5)
3.01
3.65
4.65
5.49
6.73
7.78
8.95
10.2
12.2
13.8
24-hr
(2.71-3.37) 11
(3.29-4.08)
1 (4.18-5.19)
(4.91-6.12)
(5.98-7.49)
(6.87-8.65)
(7.83-9.93)
(8.86-11.3)
(10.3-13.5)
(11.6-15.3)
3.55
4.29
5.45
6.40
8.92
10.2
11.5
13.5
15.2
7.77
2-day
(3.20-3.95)
1 (3.88-4.78)
1 (4.92-6.06)
(5.75-7.11)
(6.93-8.62)
(7.90-9.88)
(8.93-11.3)
(10.0-12.8)
1 (11.6-15.1)
1 (12.9-16.9)
3.77
4.57
5.80 IF
6.80 IF
8.26 IF
9.47
10.8
12.2
14.3
16.0
3-day
(3.43-4.19)
4.00
(4.15-5.06)
4.85
(5.26-6.42)
(6.16-7.52)
(7.43-9.12)
(8.46-10.5)
(9.56-11.9)
(10.7-13.5)
(12.4-15.8)
(13.8-17.8)
6.15
7.21
8.75
10.0
11.4
12.9
15.1
16.9
4-day
(3.66-4.43)
(4.43-5.35)
(5.60-6.78)
(6.56-7.93)
(7.92-9.62)
9.78
(9.03-11.0)
(10.2-12.5)
(11.5-14.2)
(13.2-16.6)
(14.7-18.7)
4.66
5.61
7.01
8.15
11.1
12.6
14.1
16.4
18.2
7-day
(4.26-5.10)
(5.13-6.14)
(6.40-7.67)
(7.42-8.92)
(8.87-10.7)
(10.0-12.2)
(11.3-13.8)
(12.6-15.5)
(14.4-18.0)
(15.8-20.1)
5.29
6.35
7.83
9.02
10.7
12.0
13.5
15.0
17.1
18.9
10-day
(4 .86-5.75)
(5.84-6.89)
(7.19-8.50)
(8.27-9.79)
(9.76-11.6)
(10.9-13.1)
(12.2-14.6)
(13.4-16.3)
(15.2-18.6)
(16.6-20.6)
6.95
8.29
10.0
11.3
13.2
14.6
16.0 17.5
19.5
21.1
20-day
(6.49-7.48)
(7.74-8.90)
(9.33-10.7)
(10.612.2)
(12.2-14.1)
(13.5-15.7)
(14.8-17.2) (16.1-18.9)
17.9 19.2
(17.8-21.1)
(19.1-22.9)
8.53
10.1
11.9
13.3
15.2
16.5
21.0
22.3
30-day
(8.01-9.10)
(9.50-10.8)
(11.2-12.7)
(12.5-14.2)
(14.2-16.2)
(15.4-17.6)
(16.6-19.1) (17.8-20.5)
(19.3-22.5)
(20.4-23.9)
10.6
21.2 22.6
12.6
14.7
16.2
18.3
19.8
24.4
25.7
45-day
(10.0-11.3)
(11.8-13.4)
(13.8-15.6)
(15.3-17.2)
(17.1-19.4)
(18.5-21.0)
(19.8-22.5) (21.0-24.0)
(22.6-26.0)
(23.7-27.5)
12.5
14.7
16.9
18.6
20.7
22.2
23.7 25.1
26.9
28.2
60-day
(11.8-13.2)
(13.9-15.5)
(16.0-17.9)
(17.6-19.6)
(19.5-21.8)
(20.9-23.5)
(22.3-25.1) (23.5-26.6) ]LE
5.1-28.5)
(26.2-29.9)
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.
Back to Top
https:Hhdsc.nws.noaa.gov/hdsc/pfds/pfds_Printpage.html?lat=38.1751 &Ion=-78.5800&data=depth&units=engIish&series=pds 1/4