SW7030905_HISTORICAL FILE_20040220

STORMWATER DIVISION CODING SHEET
POST -CONSTRUCTION PERMITS
PERMIT NO.
SW
DOC TYPE
El CURRENT PERMIT
❑ APPROVED PLANS
?I HISTORICAL FILE
DOC DATE
%
YYYYMMDD

• . . o
RECEIVED
ENGINEERING
TRANSMITTAL LETTER
µ� OL s A,/v� r! G .t 7 y Y 9
We are trans;� fitting:
ov'� Attached
❑ Under Separate Cover
❑ Via email / ftp
The.following items:
w' Plans
❑ Drawings
❑ - Application/Fee
CH Engineering, PLLC
4601 lake Boone Trail
Raleigh, NC 27607
919.788.0224
919.788.0232 (fax)
FEB 2 0 2004
D}!dQ'WARC
DATE: �� �i�o y JOB NO:
RE: %vK
Delivered via:
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DESCRIPTION
.2
e-' le A o f a /,- -&.3
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For Approval ❑ Approved as Submitted
iYFor Your Use a Approved As Noted
ce"'As Requested ❑ Returned for Revisions
o For Distribution ❑ For Review and Comment
II 1�,k"I .. '/',. ' JCL...f '5—
S �( C-02 �/ L� t � L/t,� / 'n G�,.rI O �n s 1 art[. d ra w w- ' •• O +� / by
a ! i A j4 J.C.. - ! �S �r+�...a 3+� l_ �i•� �d
1d L • /
Signed

RECEIVED
NATURE AND PURPOSE OF PROJECT &
STORMWATER MANAGEMENT NARRATIVE FEB 2 0 2004
EDENTON ARMORY
MOTOR VEHICLE STORAGE COMPOUND DWrq_Wn pO
This project consists of upgrading an existing National Guard Armory in Edenton to
provide for an expanded Motor Vehicle Storage Facility. The existing facility consists of
a brick single story building with a combination of concrete and asphalt parking
surrounding the facility. North of the the facility resides the Edenton Municipal Airport.
The site which is targeted for the expansion is an existing grassed field west of the
ArmoryBuilding . It is bordered on the west and south by asphalt roadways, SR 1134.
and NC 94 NCDOT indicated that the area was not an AEC (Area of Environmental
Concern) as defined by CAMA. No modifications of the existing building is proposed
at this time although two new buildings of approximately 50' x 80' are proposed on the
western extreme of the site. The parking surfaces and drives will consist of a combination
of concrete and asphalt surfaces. Areas not paved will be grassed.
The site drains south under NC 94 and eventually into the Chowan River. According to
FEMA mapping on file at the adjacent NCDOT Division of Highways office, the site
does not lie with the 100 year floodplain. Drainage ditches surround the east and
southern portion of the site routing storm drainage under NC 94. The soil beneath the
topsoil consists of low plasticity clays, clayey sand, and clayey silts. Although the site
had experienced considerable rainfall prior to the time of soils investigation it appears that
the groundwater depth is about 5 feet.
The accompanying plan reflects grading the site with a slight increase in grade along the
east and southern boundaries of the proposed pavement. The stormwater will be
collected and treated in a bioretention basin on the east side of the proposed parking Iot.
Total impervious surface includes approximately 1.59 acres comprised of concrete,
asphalt paving and building. The bioretention basin is designed to store the 1 inch runoff
for the site. Calculated volume requirements for the I inch runoff is 6030 cu. ft. (pg. 4 of
calculations), the provided volume in the bioretention basin is 12,770 cu. ft ( pg 5 of
calculations). The surface area requirements for the bioretention basin is 4759 s.f. (pg 3
calculations), provided surface area is 9900 s.f. ( pg 10 calculations). The basin therefore,
exceeds the requirements for handling the I inch runoff and the surface area requirements
for a bioretention basin.
The proposed sediment basin will be converted to a bioretention basin after the site is
stabilized. The sediment basin will be cleaned out and excavated to elevation 9.75. 50 LF
of perforated 6 in. ABS pipe in sock shall be placed at bottom of basin, and #57 stone
replaced on face of dam. Place select soil with following soil mixture: sand approx. 70%,
clay approx. 10%, and loam approx. 20%. See attached USDA soil triangle for additional

assistance in selection of soil suitable for bioretention basin. Geotechnical engineer must
approve select soil prior to placement in bioretention basin. Select soil shall be placed to
elev. 10.75 ft. Plant basin with water tolerant grasses such as blue joint, tufted hairgrass,
and or birdsfoot trefoil or approved equal native brass.

Figure 15. Soli Trl uW* of the Back Textural Classes, From Prince George's Co,1993
U.SDA. TEXTURAL TRIANGLE
100% clay
90 10
80 20
70 Clay 30
60 40
0
6 50 Silty 50o's.
c cs Cy �f
Q 40 5c^dv ,
00
cloy A C'ay Silty
clay
30 Scr,cy acy iocm loam
lour, 70
20 80
- 10 — s.. S��v-� �- �Slit a
ram:_ loam 0
=_ - -- - - Silt
Sand Y��.
90 ^��BD 70 - ..-60 =—�-• 50 40 30 20 10
100� sand ♦� 100% sift
Percent scnd
SUITABLE PLANTING SOIL
FOR BIORETENTION

NATURE AND PURPOSE OF PROJECT &
STORiNIWATER MANAGEMENTNARRATAVE
EDENTON ARMORY
MOTOR VEHICLE STORAGE COMPOUND
This project consists of upgrading an existing National Guard Armory in Edenton to
provide for an expanded Motor Vehicle Storage facility. The existing facility consists of
a brick single story building with a combination of concrete and asphalt parking
surrounding the facility. North of the the facility resides the Edenton Municipal Airport.
The site which is targeted for the expansion is an existing grassed field west of the
Armory Building . It is bordered on the west and south by asphalt roadways, SR l 134
and NC 94 NCDOT indicated that the area was not an AEC (Area of Environmental
Concern) as defined by LAMA. No modifications of the existing building is proposed
at this time although two new buildings of approximately 50' x 80' are proposed on the
western extreme of the site. The parking surfaces and drives will consist of a combination
of concrete and asphalt surfaces. Areas not paved will be grassed.
Tile site drains south under NC 94 and eventually into the Chowan River. According to
FEMA mapping on file at the adjacent NCDOT Division of Highways office, the site
does not lie with the 100 year floodplain. Drainage ditches surround the east and
southern portion of the site routing storm drainage under NC 94. The soil beneath the
topsoil consists of low plasticity clays, clayey sand, and clayey silts. Although the site
had experienced considerable rainfall prior to the time of soils investigation it appears that
the groundwater depth is about 5 feet.
The accompanying plan reflects grading the site with a slight increase in grade along the
east and southern boundaries of the proposed pavement. The stormwatcr will be
collected and treated in a bioretention basin on the cast side of the proposed parking lot.
Total impervious surface includes approximately 1.59 acres comprised of concrete,
asphalt paving and building. The bioretention basin is designed to store the 1 inch runoff
for the site. Calculated volume requirements for the 1 inch runoff is 6030 cu. ft. (pg. 4 of
calculations), the provided volume in the bioretention basin is 12,770 cu. ft ( pg 5 of
calculations). The surface area requirements for the bioretention basin is 4759 s.f. (pg 3
calculations), provided surface area is 9900 s.f. ( pg 10 calculations). The basin therefore,
exceeds the requirements for handling the I inch runoff and the surface area requirements
for a bioretention basin.
T,_ q.,. adJ,,— - S-C-LJ-r-&
- aw -4

C ENGINEERING
-Afth., ___j
TRANSMITTAL LETTER
TO:
We are transmitting:
ce� Attached
❑ Under Separate Cover
❑ Via email / ftp
The.following items:
o . Plans
❑ Drawings
❑ - Application/Fee
CH Engineering, PLLC
4601 Lake Boone Trail
Raleigh, NC 27607
919.788.0224
919.788,0232 (fax)
DATE: / JOB NO:
RE:
0Aft z7o
Delivered via:
❑ Courier
❑ Overnight Delivery
@' Mail
❑ Plats
❑ Specifications
❑ Shop Drawings
❑ Other
❑ Digital Files
❑ Change Orders
o Documents
COPIES DESCRIPTION
r _ �•s a
❑ For Approval
ur' For Your Use
Q' As Requested
❑ For Distribution
r 1
t 4C`�r �R
r�C
❑ Approved as Submitted
❑ Approved As Noted
❑ Returned for Revisions
❑ For Review and Comment
L�
V 'V lr/ � 14 // G O h. � / C,s4 ✓ O
V. _ _ ce
j
/� t //
Signed � --
.do

CENGINEERING
January 6, 2004
Mr. William Moore
Environmental Engineer
Washington Regional Office
943 Washington Square Mall
Washington, North Carolina 27889
Re: Stormwater Review SW7030905
Edenton Armory Storage Compound
Dear Mr. Moore:
This letter is in response to your letter of November 6, 2003 regarding the referenced project.
1. Site plan includes entire project area including buildings proposed on the west side as
requested.
2. Treatment for one -inch runoff is provided in bioretention basin proposed on cast side of
property.
3. The drainage /runoff from the area noth of the proposed parking lot, the entrance drive and
the proposed parking lot all drain to the proposed bioretention basin. Part of the area at the
southwest corner of the site will not be draining to the BMP. However, the proposed 13MP
exceeds the requirements for 1 inch runoff and surface area requirements for a bioretention
basin
4. Attached are the i inch runoff and the bioretention basin calculations.
5. Attached is the revised stormwater narrative
If you have any questions or need additional information, please do not hesitate to contact us.
Sincerely,
414-� CJLX
Maha Chambliss, PE
0 PO Box 30128, Raleigh, NC 27622 • TEL 919,788.0224 • FAx [phone]

Edenton National
Guard �6,Bp9 C
- _ -- ...............
♦ _ pis
a 2• �.�
Tr
V _ P
Existing Use: Wooded & Railroad corridor
I Area 4 62° Ac
12= 5,76: in/br '41 � C���,,_
qq rr y��l�p1y
Am
I
pAreas- Exist' nS:._._...- ____..: SF -AC -T C C x %A --
1527 ._ i - - 0.04- 0 9_.. 0.01
i
' rds 0 0.00 -0.9 0.00
Aui
Ming. 0 0.00 0.9 0.00
--------------
Reil corridor 0 0.0.0 0.30 0.00
Undisturbed,Open_Space 199722.6 4.58 -'„_- 0.20 _- _- _._ 0.20
_-.-_-.- _._. -- -
-.._4_62 .._ - - - ..._..... _..: _. ... -.
0.12
-............ - - ---------- . -- -- - --- --
p e "C" 2
Com osit 1 �
Q2- =.21_x 5.76. x 4.62.= - -- -_ .... _ W5.6 CFS._..-_.
7.FCFS ------ -- --- ----- -- -- -- - . .._..
Post Development Runoff (entire site)-_.- _.._ _ Area
C %A
SF AC C x
i Areas -Proposed , _ _ .. _..._.:_ AsphaH Parking lBldgs _..__ 69260.4 1,59 0.9 0.31
_. -_ - - _.. - ------_.
- _.. - - - - - --- -- - -- - _... - ------ ___`- - --- 0--_ - 0.000 .3- 0,00. - ...
1 e dscapped/grass .__ _ -- _ _ _ .-1785996 t--0.41----- = --- 0.25- -- - 0_02 .. .
1 I Undisturbed Open Spacei 114127.2 _ 2.62• 0.20 0.11 I

z

&*4,
------------
Edenton- Bioretention ba#!n sizing_
77"Bio-Retention
Calculations
LOU!
-Basin 1
F C C x A
!Asp lty�a lop 69042 0.9 62137.80
_EK
Undisturbed Buffer 0 0.2 0.00
M-1,
0 0.9 0.00
W. U7
Grass Areas 132241 0.25 33060.25
... . .......
.8
Total:: 201283 95198
4.620821 94: Ac
Sand Bed
_L(5%'ofsum)__
----------------- 1�95198 X0.06
IMIT
--- -
:4759.9025 !SF
MM
Surface area req'd-4759ist
Total surface f
2174,
USE BIORETENTION BASIN WITH SAND
�'A

1 Inch Runoff Volume Calculations
Project Name:; :Edenton National Guard
Job Number::: AS 002
Designer-Maha
Date: 1215/03:
Pond Drainage Area Description
Total DA = 4.62: acres
Impervious Area = 1.59: acres
DA % impervious = 34.42%::
Find volume to be controlled from 1 Storm
% Impervious 34.4%
Rv-.05 +0.0091 NC DENR BMR manual-Rg 6
�Rv-runoff Oefff-storm runq2ffinches )/storm rainfall (inces)
If= % imperv:ious- DA (acres / lmpervious portion of DA
tRv= 0.05+.009(34.4)
I RV= 0.35961!
For Volume Yhat must be controlled.
'Vglume= Design rainfall (Rv) DA)
'Volume= Vinch rainfall*Rv*1/12 (ft/in)*4.62 Ac
Volume--. ---.0.138:acre-ft
Votume= 6030.7078; cu. ft.
i
4

2Year
Chainsaw Routing Method
Project Name:
Edenton
Project p :
As002
Dale:
11.26.03
Operator:
MAC
Title:
2 Year Storm Routing
Hydrograph:
Op
12.0 CFS
Tp =
20.0 minutes
dT ;
1.0 minutes
Stage -Storage
Ks= 11110.0
b =
1.12
Zo =
10.8 feet
Initial Water Level :
r =
10.8 feet
Computed Results:
Normal Surf. Area =
0.000 acres
Max. Surf. Area =
0.290 acres
Peak Elev. =
11.88 feet
Peak Stage =
1.1 leet
Peak Outflow =
4.27 CFS
�7. Volume Stored =
12770.0 It'
CH Engineering
P.O. Sox 30128
Raleigh, NC 27622
Riser/Barrel
N =
1.00
Dr =
12.p0 inches
Cw =
3.30
Zcr =
11.25 feet
Db =
15.00 inches
Cd =
0.65
Bar. Invert=
7.00 feet
Orifice:
N =
0.00
D =
0.00 inches
Cd =
0.00
invert =
0.00 feet
Weir 1:
L =
7.00 feet
Zcr =
11.75 feet
Cw. =
3.00
Weir 2:
L =
0.00 feet
Zcr =
0.00 feet
Cw -
0.00
System Loading and Response
14.0
12,0
ouerow
100
B0
`u
0 6.0
40
2,0
0.0
0.0 10.0 20.0 30.0 40,0 500 60.0
Time (min)
Time
min
Inflow
cis
Storage
ftA3
Stage
tt
Outflow
cis
Riser(weir)
cis
Riser(orif.)
cis)
Barrel
(cfs)
Orifice
(cis
Weir 1
cfs
Weir 2
cis
0.0
0.0
0,0
10.8
0.00
0.00
0,00
11.32
0.00
0.00
0.00
1-0
0.1
0.0
10.8
0.00
0.00
0.00
11.32
0.00
0.00
0.00
2.0
0.3
4.4
10.8
0.00
0.00
0.00
11.32
0.00
0.00
0.00
3.0
0.7
22,1
10.8
0.00
0.00
0.00
11.32
0.00
0.00
0.00
4.0
1.1
61.3
10.8
0.00
0,00
0.00
11.33
0.00
0.00
0.00
5.0
1.8
130.0
10.8
0.00
0.00
0.00
11.35
0.00
0.00
0.00
6.0
2.5
235.5
10.8
0.00
0.00
0.00
11.37
0.00
0.00
0.00
7.0
3.3
383.9
to.$
0.00
0.00
0.00
11.40
0.00
0.00
0.00
8.0
4.1
580.4
10.8
0.00
0.00
0.00
11,44
0,00
0.00
0.00
9.0
5.1
829.2
10.8
0.00
0.00
0.00
11.49
0.00
0.00
0.00
10.0
6.0
1132.9
10.9
0.00
0,00
0.00
11.55
0.00
0.00
0.00
11.0
6.9
1492.9
10.9
0.00
0.00
0.00
11.61
0.00
0.00
0.00
12.0
7.9
1909,2
11.0
0.00
0.00
0.00
11,69
0.00
0,00
0,00
13.0
8.7
2380.4
11.0
0.00
0,00
0.00
11.76
0.00
0.00
0.00
14.0
9.5
2903.9
11.1
0.00
0.00
0.00
11.B5
0.00
0.00
0.00
15.0
10.2
3475.5
11.1
0,00
0,00
0.00
11.94
0.00
0.00
0.00
1&0
10.9
4090,0
11.2
0.00
0.00
0.00
12.03
0,00
0,00
0,00
17.0
11.3
4741.3
11.2
0.00
0.00
0.00
12.13
0.00
0.00
0.00
18.0
11.7
5422.1
11.3
0.05
0.05
0.67
12.23
0.00
0.00
0.00
19.0
11.9
6121.7
11.3
0,27
0,27
1.21
12.33
0.00
0.00
0.00
20, 0
12.0
6821.2
11.4
0.58
0,58
1.57
12.43
0.00
0.00
0.00
21.0
11.9
7506.2
11.5
0,96
0,96
1.85
12.53
0.00
0.00
0.00
22.0
11.7
8164.2
11.5
1.37
1.37
2.09
12.62
0.00
O,W
0,00
23.0
11.3
87134.3
11.6
1.80
1.80
2.28
" 12.70
0.00
0.00
0.00
24.0
10.9
9357.3
11.6
2.22
2,22
2.45
12.77
0.00
0.00
0.00
25.0
10.2
9875.3
11,7
2.59
2.62
2,59
12.84
0.00
0.00
0.00
26.0
9.6
10334.4
11.7
2.71
3.00
2.71
12.90
0.00
0.00
0.00
27.0
9.0
10748.4
11.7
2.81
3.35
2.81
1 Z.95
0.00
0.00
0.00
28.0
8.4
11120.1
11.8
2,90
3.67
2.90
13.00
0.00
0.00
0,00
29.0
r 7.9
11452.4
11.8
3.07
3.97
2.98
13.04
0.00
0.10
0.00
30.0
7.4
11742.6
11.8
3.28
4.24
3.04
13.08
0.00
0.24
0.00
31.0
6.9
11990.4
11.8
3.49
4.47
3.09
13.11
0.00
0.39
0.00
32.0
6.5
12197.7
11.8
3.68
4.66
3.14
13.14
0.00
0.54
0.00
33.0
6.1
12367.5
11.9
3,84
4,82
3.17
13.16
0.00
0.67
0.00
34.0
5.7
12502.7
11.9
3.98
4.95
3.20
13.17
0.00
0.78
0,00
35.0
5,4
12606.6
11.9
4.09
5.05
3,22
13.19
0.00
0.87
0.00
36.0
5.0
12682,3
11.9
4.17
5.13
3.24
13.20
0.00
0.93
0.00
37.0
4.7
12733.0
11.91
4.231
5.18
3.25
13.201
0.00
0.98
0.00
R ETBASIN.XLS
S

2YBar
Time
min)
Inflow
(cfs)
Storage
(ft^3
Stage
ft)
Outflow
(cf-5)
Riser(weir)
(cls
Riser(orif.)
cls
Barrel
cfs
Orifice
cls
Weir 1
cfs
Weir 2
cfs
38.0
4A
12761.3
11.9
4.26
5.21
3.26
13.21
0.D0
1.00
0.00
39-0
4,1
12770.0
11.9
4.27
5.21
3.26
13,21
0.00
1.D1
0.00
40.0
3,9
12761.6
11.9
4.26
5.21
3.26
13.21
0.00
1.00
0.00
41.0
3,6
12738.0
11.9
4.23
5.18
3.25
t3,20
0.00
0.98
0.00
42.0
3.4
12701.5
11.9
4.19
5.15
3.24
13,20
0.00
0.95
0,00
43.0
3.2
12653.6
11.9
4.14
5.10
3.23
13.19
0.00
0.91
0.00
44.0
3.0
12596.1
11.9
4.08
5.D4
3.22
13.19
0.00
0,86
0,D0
45.0
2.8
12530.3
11.9
4.01
4.98
3.21
13.16
0.00
0.80
0.00
46.0
2.6
12457.3
11.9
3.93
4.91
3,19
13,17
0.00
0.74
0.00
47.0
2.5
12378.4
11.9
3.85
4.83
3.18
13.16
0.00
0.68
0.00
Q 0
2.3
12294.4
11.8
377
4.75
3.16
13.15
0.00
0.61
0.00
R ETBASIN. XLS

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FROM : CH ENGINEERING PHONE N0. : 9198486761 Jain. 06 2004 02:02PM P1
ENGINEERING
[]I
FAX TRANSMISSION
DATE: l oa
TO: 41:11 ocrc- -
CH Engineering, PLLC
4601 Lake Boone Trail
Raleigh, NC 27607
919,788.0224
919.788.0232 (fax)
s0B NO -
FAX: 2 S 2 . `t q 921
FROM: '7n 4- " a L,6 /'S3
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ory
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CENGINEERING
TRANSMITTAL LETTER
TO:
We are transmitting:
Q---'Attached
❑ Under Separate Cover
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The following items:
0' Plans
❑ Drawings
❑ Application/Fee
CH Engineering, PLLC
4601 Lake Boone Trail
Raleigh, NC 27607
919.788.0224
919.788-0232 (fax)
DATE:WHO } JOB NO:
RE:
Delivered via:
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'I d8
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Signed

O=O� w A r�9QG
Michael F. Easley, Governor
William G. Ross Jr., Secretary
North Carolina Department of Environment and Natural Resources
Alan W. Klimek, P. E. Director
Division of Water Quality
Coleen H. Sullins, Deputy Director
Division of Water Quality
DIVISION OF WATER QUALITY
November 6, 2003
NC National Guard
Attn: Mr. William E. Johnson
4105 Reedy Creek Rd
Raleigh, NC 27607
Subject: Stormwater Review SW7030905
Edenton Armory Storage Compound
Chowan County
Dear Mr. Johnson:
This office received your stormwater application and
supporting information on September 8, 2003. I discussed the
proposed project with Maha Chamblis, CH Engineering, and received
a revised site plan on October 3, 2003. On -October 30, 2003, I
visited the site to look at existing site conditions and to get a
better understanding of possible stormwater treatment alternatives.
I plan to discuss treatment alternatives and modifications to the
stormwater application with Ms. Chamblis in the next few days.
The following information is needed to complete the
application package:
(1) site plan that includes the entire project (buildings on
West side, as well as new parking area)
(2) stormwater plan that shows adequate treatment for one -inch
runoff from entire project area
(3) site plan showing drainage basins, details and
specifications for treatment alternative(s)
(4) stormwater runoff and design calculations
(5) detailed stormwater narrative
In addition, I understand that the Division of Land Quality
issued an approval for the erosion control plan on September 29,
2003. This plan showed a 2-acre site for a parking lot. Since the
scope of the entire project appears to be more than 2-acres, I
suggest that you contact Mr. Pat McClain, Land Quality Section,
Washington Regional Office, at [phone], to determine if a
revised erosion control plan is needed.
N. C. Division of Water Quality 943 Washington Square Mall Washington, N.C. 27889 'telephone [phone]
NA
NL[JENi�
FAX [phone]

NC National Guard
Mr. William E. Johnson
November 6, 2003
Page Two
The above information relating to the stormwater appl.icaton
must be submitted within 30 days, or your project will be returned
as incomplete. If you have questions, please feel free to contact
me at [phone], extension 264.
Sincerely,
l
William J ore
Environmental Engineer
Washington Regional Office
cc: CH Engineering
Pat McClain, Land Quality
C�aowan County Planning & Inspections
ashington Regional Office

August 2I, 2003
CH Engineering
4601 Lake 13oone Trail
Ralcigh, NC 27607
Attw Mr. Torn I-iepler
Re: Report of Subsurface Investigation
National Guard Armory Additions
Edenton, North Carolina
GcoTechnologies Project No. 1-43-1167-EA
Gentlemen:
3200 Wellington Court, Suite G
Raleigh, North Carolina 27615
919-954-1514
fax [phone]
RECEIVED
SEA' 8 2003
DWQ-WARD
Geofechnologies, Inc. has completed the authorized subsurface investigation to evaluate site
grading and subgrade preparation conditions for a proposed expansion of the existing National Guard
Armory in Edenton, North Carolina. Subsurface conditions at the site were investigated by
performing nine hand auger and dynamic cone penetrometer borings at the locations shown on the
attached Figure 1. The locations were staked in the field by survey personnel, and the indicated
locations should be considered accurate. The borings were advanced to termination depths of 5 to 9.5
feet below existing site grade using a dynamic hand cone penetrometer at selected intervals to
evaluate the consistency and density of the subsurface soils. This report presents the findings of the
investigation and our recommendations for preparation of the site and for design and construction of
the proposed additions.
SITE AND PROJECT DESCRIPTION
It is our understanding that an open grassed area adjacent to the existing National Guard
Armory in Edenton, North Carolina is under consideration for placement of asphalt and concrete
pavement sections for storage of equipment. The area selected for the new construction appears to
have been graded at one time for a parade Field and is now covered with a relatively thick stand of
mown grass. The site is relatively level, showing no more than a few feet of topographic relief across
the areas to be developed. It appears that the area to be developed is slightly higher than the
surrounding area and thus It IS reasonably well drained for (lie site proximity.
At the time of our investigation, heavy rainfalls had recently fallen, 'Lind the main area
represented by test borings HA-1 through FIA-6 was quite wet with isolated areas of standing water,
particularly in the vicinity of test boring HA-6. Test boring i-IA-7 is in an area with more topography
and was dry as was the area around test borings HA-8 and HA-9. It is our understanding that the
proposed construction will include a 6 inch concrete slab underlain by 8 inches of CABC in some
areas and 2 inches over 8 inches of CASC in other areas. A small building is planned for the area of
borings HA-8 and HA-9.
Ge?otoc17f1fcal c.ul<:i Conslarc,`fiOn Nklfofiok, l aliri,� .S< rviee35

(_'II Eligiuccring
SUBSURFACE CONDITIONS
A generalized subsurface profile prepared from the test boring data is attached to this report
as Figure 2 to graphically illustrate subsurface conditions encountered at this site. More detailed
descriptions of the conditions encountered at the individual test boring locations are then presented
on the attached test boring records.
The subsurface profile was found to consist of a surface veneer of topsoil which ranged from
only a few inches in thickness at test locations HA-8 and FIA-9 to approximately 6 inches in
thickness in other areas. This topsoil veneer was generally underlain by low plasticity clays, clayey
sands, or clayey silts which typically probed soft to a depth of 6 to 12 inches below the existing
surface. In a few areas, such as at test location HA-6, the probe rod could be extended through soft
soils to a depth of 18 inches. With increasing depth, the borings generally encountered near surface
clays and silts which were relatively stiff typically exhibiting dynamic ]land cone penetration
resistances of 6 to 8 blows per increment and higher in the upper 2 feet. With increasing depth, the
soils generally became somewhat softer penetrating into highly plastic clays in several areas. Test
borings hIA-I through HA-7 were terminated in silty clays or clayey silts at a depth of 5 feet below
grade. Test borings HA-8 and HA-9 were extended to a depth of 9 to 9.5 feet and encountered a
stratum of clean tine to coarse sand below a depth of 7 to 7.5 feet.
Perched water was present at the interface with the much farmer soils present at a depth of
about 6 to 12 inches below grade in virtually all of the borings at the tirne of this investigation due to
recent heavy rainfalls. However, it appears that the true groundwater table probably exists at depths
of 4 to 5 feet or more. The soils generally were very wet at the surface, became somewhat drier
below those surface soils to a depth of 2 to 2.5 feet, and then began to become more moist below that
depth. The sands penetrated at test locations HA-8 and HA-9 were extremely wet, and the hand auger
borings could not be advanced deeper than 2 feet into the stratum due to the presence of what is
believed to be a true groundwater table.
RFCONINIENDATIONS
Tile fallowing recommendations are made based upon a review of the attached test boring
data, our understanding of the proposed construction, and past experience with similar projects and
subsurface conditions. Should site grading or structural plans change significantly from those now
under consideration, we would appreciate being provided with that information so that these
recommendations may be confirmed, extended, or modified as necessary. Additionally, should
subsurface conditions adverse to those indicated by this report be encountered during construction,
those differences should be reported to us for review and comment.
Site Grading Considerations. The near surface soils on this site were extremely wet at the
time of this investigation due to the wet weather pattern which has dominated the State over the last
six to seven months. If earthwork is instituted during wetter times such as currently exist, it will be
necessary to strip the topsoil with tracked equipment wind rowing the material for loading into trucks
for removal from the site. The upper 12 inches of soil was very soft in many areas and likely will
have to be disced, dried, and reconlpacted in order to provide adequate support. If it is desired to fast
track the project, consideration should be given to blading off the topsoil and the upper 8 to 12 inches
L' y,�,,,;t:a.: 1AtYi.. ;i
hft744 0k-- u

('11 Unt;incrring
Altrfl.;l "1, 10111
1 `;fly~ .r
of very wet ,Soils and then hrirrging the cite hat:k to grade with it snore select lnutcrial such as a silty
sand, clayey sand, or clean sand. If it is desired to use the on -site soils, the contractor will have to
repair the near surface conditions by discing, drying, and recompacting. This will necessitate limited
undercut to depths of 6 to as much as 12 inches in some areas followed by recompaction. We
anticipate that these type repairs would be needed in the area of test borings HA-1 to HA-6 where the
surface soils are quite west. We anticipate that minimal surface repair probably would be necessary at
test locations HA-8 and FIA-9 due to previous amendment of the near surface soils in that area with
gravel.
Following stripping of' topsoil, the site should be proofrolled with a partially loaded dump
truck or similar piece of equipment in order to identify those areas needing repair. As previously
indicated, we anticipate that the upper 12 inches of soil will be soft and will rut under the action of
rubber tired equipment in the main area proposed for pavement. Those soils will either have to he
undercut or be reworked and properly compacted to provide adequate support for a pavement
structure. Ideally, we suggest giving consideration to importing approximately 12 inches of a more
select material to use as it sub -base beneath the pavement structure. All new fill placed on the site as
well as the finished subgrades should be reworked and compacted to not less than 95% of the
standard Proctor maximum dry density except in the final foot beneath the base course stone where
this requirement should be increased to 98% of the standard Proctor maximum.
Foundation Support. The structure proposed in the area of borings HA-8 and NA-9 may be
supported on shallow spread footings or a turned down slab. Foundations should be sized for a
contact stress of 2,500 psf subject to the restriction that column and wall footings have least
dimensions of 24 and 16 inches, respectively. Figures 3 and 4 provide an indication of settlement
potential for it range of column and wall loadings. Individual footings should be inspected at the time
017 construction to evaluate: the need for repair. We anticipate that it may be necessary to neatline
overexcavale through some softer soils to a depth of 3.5 to 4 feet and then backfill to design subgrade
if individual spread footings will be used. If a turned down slab is used, overexcavation and stone
replacement likely will not he needed. We understand that a structure may also be placed in the area
of FIA-1 and HA-4. We do not anticipate that any repairs would be required in that area: however,
footing bottoms should be inspected at the time of construction to evaluate the need for repairs.
Pavement Design Considerations. We understand that the site will be subject to
approximately 20 vehicles per clay with live of those being tractor trailers. The on -site soils likely
will exhibit a design subgrade CBR value of approximately 5% when properly recompacted to not
less than 98% of' the standard Proctor maximum. A C131Z of 5%, with the assumption of five tractor
trailers and 15 light trucks per day will result in the need for a pavement structure consisting of 3
inches of asphalt over 8.5 inches of CA13C base course stone, ff 12 inches of more select sandy soils
are brought in to improve grading on the site and to provide for slightly better drainage, the design
C131Z value will likely increase to 8% which would render a pavement structure consisting of 2 inches
of asphalt over 9.5 inches of stone adequate for the anticipated traffic. We support using a nominal
section of either 2 over 9 or 3 over 8 depending on the subgrade materials.
The subgrade soils will exhibit a design subgrade modulus value on the order of 100 pci
which may be used for design of the concrete slab -on -grade elements. If heavy area loads will be
supported on the concrete slab -on -grades, we would appreciate being provided with that information

iur r, I„r:
.lill�u'.I 'I 'I III;
I',11�r I
'.„ 111;11 'VC 1';01 lilliviili' ';r'111�'lllr'lll r";Illllilll" . A r'rllicn-lv 11;IVr'llli,111 wr'liojl coll5l';1ing 4 6) Inl:hes Ill
4,000 psi concrete over 3 inches of CAI3C will be adequate for the anticipated traffic loadings.
SUNIIVIARY
In summary, subsurface conditions on this site are somewhat poor at present due to the very
wet conditions which have occurred during the early part of the summer. Earthwork on this site Could
he greatly facilitated by stripping topsoil with tracked equipment and then waiting for a period ol' dry
weather to prepare the site. Even with dry weather, we anticipate that it will be necessary to repair
the upper 12 inches of soils in the main fill area before those soils will be suitable for support of the
proposed pavement structure. Ifs on -site soils will be used for the pavement structures, we suggest
increasing the asphalt section to 3 inches of asphalt over 8 inches of stone. If site grades are raised
with a more select sandy material after removal of the topsoil and soft soils, the pavement section
Could be reduced to 2 Inches of asphalt over 9 inches of stone.
Geo`l'echnologies, Inc:. appreciates the opportunity to be of service on this phase of the
project. Please contact us if you have any questions concerning this letter or if we may be of
additional service on this or other projects.
Sincerely,
GeoTechnol ogles, Inc
Edward B. Hearn, P.E.
NC Registration No. 9520
David L. Israel, P.E.
NC Registration No. 14319
EM-1/lam
Attachments
031167ea.doc
CA401 g zY
W.a crNx� : c,r �
91o�f�s, *

45
H A 1�7
HA-9
1V
i � k
T!
14A -7
.6v
\,HA-3
HA4' % H A V
Ao-
HA-11 -
"H Z.
HA-6:/
PROJECT: SCALE: Not to Scale
V.
1-03-1167-EA
National Guard Additions G oTe (46 ol 6 JOB No.
Edenton, North Carolina FIGURE No: 1

Depth (Feet) GENERALIZED SUBSURFACE PROFILE
LEGEND
HA- 1 HA- 2 HA- 3 HA- 4 HA- 5 HA- 6 HA- 7 HA- 8 HA- 9 ® Topsoil
o 1�1
III � Low Plasticity kilt
I
1 11 9 8 10 10 15+ � 10 13 Low Plasticity C:;ay
Low Plasticity C:,ay to Silt
Plasticity
High y
2 7 12 6 7 i 9 15+ I 9 ty _:.a
Silty Sand
3 6 3 4 12 9 8 4 4 ® Low Plasticity S-ilt to Clay
/Z
High Plasticity Silt
4 6 Moderate Plastl-=ity Clay
Silty Gravelly S.;.nd
5 8 15 7 9 8 6 13
Low Plasticity Silt to Silty Sand
6 VAI Clayey Sand
❑ 8 Dynamic Con, Penetration
7 5 8 \� Groundwater a' Time of Boring
8
9
10
10
PROJECT: SCALE: As Shown
JOB No:1-03-1167-EA
National Guard Additions % - -
Edenton, North Carolina FIGURE No:2

ESTIMATED SETTLEMENT vs COLUMN LOAD
1.8
i
--
1.6
1.4 -
i
k
�
1.2
cn
�+
1
'
W
0.8
0.6
i
i
i
0.4
i
I,
0.2
0
0 50 100 150 200 250 300
Column Load (kips)
Assumes 2500psf bearing pressure. FIGURE 3

1.4
1.2
s` 0.8
Z
(D
U)
j 0.6
0.4
AIPa
M
Estimated Settlement of Wall Footing
0 500 1000 1500 2000 2500 3000 3500
Contact Stress (psf)
Estimated settlement of
wall footing with indicated contact stress.
f-2ft Wide Fc _'irr�
�3ft Wide F.--._,ti;-.g
FIGURE 4

DYNAMIC HAND CONE
RECORD
Did"I'll DVS(TIPTION 1114NATION 1111'All'A'RATION PFR HLOWS PER
(FT.) 0.111.) 1 N C I ? F, N11 V NT 1 3/4"
OJ) 0 10 20 40 60 100
0.5
15
4.0
5.0
Topsoil
ll
6
Light Gray Clayey Fine Sandy SILT
NIL,
Uit (irm, Olangc Silty CLAY
cj-
Light Gray A-, Oninge 4lott[cd Clayey SILT to Silly
CLAY
Cl-
NIL
al 5'
Perched water at'15'. Probed soft to 12".
JOB NUM131CR
BORING NUMBER
DATE
�MIIIIIIIIIIIIIII
GeoTe l n 'logies, Inc
PAGE 1 OF 1

DYNA N I I C I L k N 1) (A) N F
I'VNETIMNIFTER RECORD
D11"I"I'll DESCRIPTION ELEVATION PENETRATION PER 13LOWS PER
(I"r.) INCH FAM VAT I 3/A
0.0 0 10 20 40 60 100
0.5
2,5
5.0
Topsoil
9
12
3
15
Light GMV &' ONLngc Fines Sand}' CLLYCY SILT
NI I
Light Gray Silly CLAY
CH
HWILI Auger To minatcd at 5'
Perched water at 2.5'. Probed soft to 12".
.1013 NUMBER
BORINC NUMBER
DATE
PACE 1 OF I
1-03-1167-EA
HA- 2
8-21-03
v (�L=mi M10 ME
,qr

1-2
10
5.0
Ill'NAN11C HAND C!)NI1
I'VNFTRONI1�:'1TR RKCORD
DESCRIPTION ELEVATION PENETRATION PER 13LOWS PER
INC'RI?MENT 13/4"
fl 1 n 2.0 JO hn 100
TO )Soil
SNI
x
G
4
7
Tan Silty SAND %vlShells
light Grav & Change Dine Sandy silly CLAY
Cl_
Light Gray Fine Sandy Clayey SILT
NIL
light Gray &. Orange Silty CLAY
Cl l
I [and Auger Terminatcd at i'
Perched water at 2.0'. Probed firm at 2".
JOB NUMBER
BORING NUMBER
DATE
1-03- l 1 b7-EA \
FIA- 3 ..
8-21-03 L�m �' 1 1
PAGE I OF I

0.0
0.3
IJ
35
50
DYNAMIC HAND CONE
PENETROMETER RECORD
1) VISCR I PTI ON VIA NATION PENETRATION PER 13LOWS PER
(1.11I..) I N CI I F, Rl V NT 1 3/4"
f) 10 21) 41) 60 100
Topsoil
10
7
12
9
Light Gray Claycv Fine Naudy SILT
MI.
Light Gray X., 01:111L! Siky CLA V
Cl.
IJUlit Gray S-, Ormi�c Clqcy S111'
mi.
Hand Augerl'erminatcd at 5'
Perched water at 2.0'. Probed soft to 8".
.JOB NUMBER
BORING NUMBER
DATE
1-03-1167-F'A
FIA- 4
8-21-03
PAGE- 1 OF I

1.0
2.0
In
5.0
DYNAMICIIAND CONE
I'VAETRONIFTER RECORD
DFISCRIPTION ELEVATION PENETRATION PER BLOWS PER
(VI'.) INCH FNI F' NT 1 31.1
in M 310 611 100
Topsoil
9
9
6
Light Gray k, Orange Silly CLAY to Claycy SILT
CL
Nil,
Light (fray Silly CLAY
CH
Light Gray k Orange Clayey SAND toSillq CLAY
K-1—L
Cl-
G i ay Clayey SILT
Boring Terininaied at 5'
Perched water at 2.0'. Probcd SDft to 10".
JOB NUMBER
BORING NUNIBER
DATE
1-03-1167-FA
HA- 5
8-21-03
PACE I OF t

DYNAMIC IIA1V1) CONE
PI:NI TIZOIVII+ rjI ,R RECORD
DFTTII D1,SC'RIPTION ELEVATION ITNETRATION PER BLOWS PER
(FT.) INCI(F,Mh'NT 1 31111,
0.0 n 1n In an rn inn
0.3
5.0
Topsoil
Light Gray & Oratsge Clayey SILT to Silty CLAY CI
ML
Iland Auger Terminated at 5'
Perched watcr tit 1.0'. Probed soft to 18".
JOB NUMBER
BORING NUMBER
DATE
1-03-1167-EA \
IJA- 6
4-21-03
V-
PAGE I OF I

2.0
5.0
DYNAMIC HAND CONE
PENETRONIETFR RECORD
DESCRIPTION ELEvA,PION PENETRATION PER BLOWS PER
0,111',j INCI FA-1ENT 1 31-1"
10 20 40 60 100
Topsoil
15+
15+
8
8
'Ian yes Orange Fine Sandy Clayey SILT
ML
Light Gray & Orange Silty CLAY
CI.
CI.I
I land Auger Terminated at 5`
Probed firm at Y and no water encountered.
JOB NU1V1BFIZ
13011ING NUMBEIR
DATE
1-03 -1 1 67-EA \ ....
HA- 7
8-21-03 % - So 1 1'-
I'AG E 1 01" 1

0.0
0.?
0.5
0.8
2.0
2.9
5,0
T5
9.5
1)YN:1MIC IfANI) CONK
PEN1+TRON-IFTER RECORD
DESCRIPTION ELEVATION PENETRATION PER BLOWS PER
INCUFAIFNT 13/4"
n In if) an (10 100
Topsoil
[0
F
6
5
10
Q
Black Silty Dine SAND w/Gravel
-
Tan to Brown Silty Fine to hlediunt SAND
SV[
Light Cray Fine Sandy Cfaycy SILT
ML
CL
Light Gray Fine Sandy SILT
[vIL
SM
Light Cara}' & Brown Silty CLAY
CL
CH
Light Gray R Tan Clayey Silty Finc SAND
SC
Brown Fine to Coarse SAND
SP
Buring Tenninated at 9.5'
Groundwater elICountered at Tat time of boring. Probed firm to 3".
JOB NUNIRF-R
BORING NUMBER
DATE
1-03-1 167-EA \
HA- 8
8-21-03
PAGE 1 OF 1

DEPTH
I,1' 1'. )
0.4
0.2
0.4
0.9
2.0
3.5
5.0
7.0
9.0
DYNAMIC 1IAND CONE
P1-;NETR0 NIP',TER RECORD
DESCRIPTION ELEVATION PENETRATION PER I3L0NVS PE R
(FT.) INCREMENT 13/4"
n in in an al 100
Topsoil
SNI
---
13
9
t
13
R
Black l' me Silly SAND w/Grayd
Ian Sill' Dine SAND
Lighl Gray Slightly silly Fiuc'San,iy clavey SILT
kiL
Light Gray Finc sandv Cl;ivcy SILT
h1L
Light Gray & Grange Silty CLAY
Cl.
Brown to Orange Clayey Silt}' Dint SANDSC
'['till Fine to Coarse SAND
SI'
raring lerrninnlc;d ;u 9'
Groundwater CRC011lltered at Tat time ol'boring. Probed firm to 3"
.JOB NUN113EII
BORING NUMBER
DATE
PAC F l OF l
1-03-1167-EA \
HA- 9
8-2 l -03 % - s a
CNgr
Q

F _
7
OIL
•�1 d
77
'7
i%
/rl
•+r..ww�/wry
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CENGINEERING
TRANSMITTAL LETTER
TO: yU,4 f�f rNGTOni RC6-10.)A L
TIM MULLlGAA) WQ (uPtR-VjSoi?
(n��Iffrn)tr±�nS; NC 2-73p9
We are transmitting:
Attached
a,- . Under, Se4awalp,C.aver..,..
❑ Via email / ftp
The owing items:
fol
Plans
❑ Drawings
❑ Application/Fee
❑ Plats
or' Specifications
❑ Shop Drawings
❑ Other
CH Engineering, PLLC
4601 Lake Boone Trail
Raleigh, NC 27607
919.788.0224
919.788.0232 (tax)
DATE: 9-5-- o 3 JOB NO:
RE:.II� �ua�Ji ��Cn1jOrJ ,��Mo2r
Delivered via:
❑ Courier
a . Overnight. Delivery
Mail
DWQ-WARQ
❑ Digital Files
❑ Change Orders
mi-' Documents
SEP 8 2003
COPIES
DESCRIPTION
I 0 i" I (-
A iP?L f c.4 i r<)rj 10 p- M
ICopy
— 4( -+� —
2
A-'S V eE �oS>
2
s POC I rf CA$j eon's
2
S7-01241 �ZkVj^-)A-C,!F CA-L[s .
C k --orz 420 , ov
❑ For Approval
❑ Approved as Submitted
❑ For Your Use
a Approved As Noted
❑ As Requested
❑ Returned for Revisions
❑ For Distribution
❑ For Review and Comment
Signed

NATURE AND PURPOSE OF PROJECT &
STORMWATER MANAGEMENT NARRATAVE
EDENTON ARMORY
MOTOR VEHICLE STORAGE COMPOUND
RECEIVED
SEP 8 2003
DWQ-WARO
This project consists of upgrading an existing National Guard Armory in Edenton to
provide for an expanded Motor Vehicle Storage Facility. The existing facility consists
of a brick single story building with a combination of concrete and asphalt parking
surrounding the facility. North of the the facility resides the Edenton Municipal Airport.
The site which is targeted for the expansion is an existing grassed field west of the
Armory Building. It is bordered on the west and south by asphalt roadways, SR 1134
and NC 94 NCDOT indicated that the area was not an AEC (Area of Environmental
Concern) ms �defined•by LAMA: -No is-pmposed
at this time although two new buildings of approximately 50' x 80' are proposed on the
western extreme of the site. The parking surfaces and drives will consist of a
combination of concrete and asphalt surfaces. Areas not paved will be grassed.
The site drains south under NC 94 and eventually into the Chowan River. According to
FEMA mapping on file at the adjacent NCDOT Division of Highways office, the site
does not lie with the 100 year floodplain. Drainage ditches surround the east and
southem portion of the site routing storm drainage under NC 94. The soil beneath the
topsoil consists of low plasticity clays, clayey sand, and clayey silts. Although the site
had experienced considerable rainfall prior to the time of soils investigation it appears
that the groundwater depth is about 5 feet.
The accompanying plan reflects grading the site with a slight increase in grade along the
east and southern boundaries of the proposed pavement. The stormwater will be
collected in ditches south and north of the pavement and retained Total impervious
surface includes approximately 1.45 acres comprised of concrete, asphalt. paveing and
building. Approximately 0.32 acres of impervious surface exists. By retrofitting existing
grass -lined ditches a total storage of 3825 cf is provided. This will theoretically contain a
5 minute duration 10 year storm and contain more than'/z inch of rainfall over the
impervious surface area. These grass -lined ditches will also serve to contain pollutants
from site runoff .