NCG070116_COMPLETE FILE - HISTORICAL_20130417

STORMWATER DIVISION CODING SHEET
RESCISSIONS .
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ELM Site Solutions, Inc.
P. O. Box 97607
Raleigh, North Carolina 27624
Phone: [phone]
Sedimentation and Erosion Control Plan
Stormwater Management Plan
Narrative Report and Assumptions
S&G Prestress Company
9767 Chappell Loop Road
Leland, North Carolina 28451
PIN:219720818887
April 13, 2011
Narrative
Summary of Existing Conditions
E I M
Site Solutions, Inc.
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The existing project development site is located in the Cape Fear River basin in Brunswick
County on a 9.19± acre parcel. The site is currently used for outdoor manufacturing of
pre -stress concrete components. The site is zoned industrial and has been in operation
since the 1970's. The site National Pollution Discharge Elimination System (NPDES)
permit # is 070116. The property drains to a tributary of Jackey's Creek (C, SW surface
water classification). The site's west property boundary is adjacent to a stream mapped
as intermittent on the USGS quadrangle sheet and the USDA soils map. This area is
subject to a 30' stream buffer that intrudes into the project site. The property is not located
within an incorporated area and therefore sedimentation and erosion control permitting
must be applied for at the Wilmington Regional Office of the North Carolina Department of
Environment and Natural Resources (NCDENR).
Site soils are HSG "A" and are predominately Lo (Leon Fine Sand) and On (Onslow Fine
Sandy Loam). The existing site hydrologic condition is characterized as 0.465 acres
impervious, 7.385 acres compacted gravel and 1.340 acres managed open space. In
addition to the stream along the west boundary, the site is surrounded by a large on -site
wooded channel to the north and off -site roadside ditches to the east and south. The site
drains via overland flow towards the sides of the site and into three drop inlets and pipe
conveyances. Two of the drop inlet and pipe conveyances drain to the ditch along Ploof
Road and the third drains to the existing on -site wooded channel. Drainage ultimately
converges at a single 48" concrete pipe culvert crossing Ploof Road. There are no off -site
run-on contributions to the built upon areas of the site. The large on -site wooded ditch
bordering the north side of the property has a very flat long slope of 0.24 percent and.
receives a small amount of run-on from off -site property. %
APR 1 8 'to"

Summary of Proposed Conditions
The work proposed is related to installing a permanent stormwater collection and
treatment system in addition to modifying drainage inlets of two existing on -site drop inlets.
The proposed improvements to the drainage collection system is being completed to
comply with the NPDES permit for maintaining a turbidity threshold of less than 50 NTU's
in the run-off from the site. The stormwater collection system routes most of the developed
site (5.140 acres) to an open sand filter. A site area of 1.787 acres is routed to a series of
two permanent rock and gravel filtration dams to be installed in the existing on -site
wooded channel. A site area of 0.783 acres drains to permanent inlet protection to be
installed at the existing drop inlet located central to the site that is piped to the roadside
ditch along Ploof Road. A site area of 0.476 acres drains directly to an on -site vegetated
channel and roadside ditch along Chappell Loop Road. The remaining 1.008 ac. of the
9.194 ac. property is most managed open space at the southwest end of the site in and
around the 30' riparian buffer. Three points where concentrated stormwater discharge
occurs have been established to serve as surface water sample collection locations for
turbidity testing of stormwater leaving the developed portions of the site.
The total disturbed area both on -site and off -site is 2.10 ac. The total area to be
revegetated is 0.800 acres. The open sand filter will serve as a temporary sediment basin
during installation of the storm drainage system and will be converted over to the
permanent sand filter function once the upstream disturbed areas are stabilized. The
temporary sediment basin will utilize a perforated 8" PVC riser and gravel filter to remove
sediment from the discharge water.
Base Assumptions
1. Handling of Contributing Offsite Drainage Areas: There is no significant run-on
from off -site properties onto the site.
2. Capture and treatment of 1.5 inch rainfall event:
Sand Filter - The sand filter is sized to capture and filter the entire volume (active
volume) of run-off generated from 1.5" of rainfall for the contributing 5.144 acres of
on -site drainage area. The active volume assumes the compacted gravel surfaces
are impervious. The percent impervious is 4.515 acres / 5.144 acres = 87.77%.
Therefore, Rv = 1.5 x (0.05 + 0.009 x 87.77) = 1.260". The water quality active
volume is 1.260" / 12"/ft x 5.144 ac. x 43,560 sf/acre = 23,528 cubic feet (cf). The
proposed active volume is 25,214 cf. The extra volume allows for 1.20' (elevation
16.20') of sedimentation depth in the forebay.
Rip -rap & Gravel Filtration Dams & Infiltration Basins "A" and "B" - The two
rock and gravel filter dams detain and filter the entire volume of run-off generated
from 1.5" of rainfall in the existing wooded ditch for the contributing 1.787 acres of
on -site drainage area. The active volume is calculated by the simple method and
assumes the compacted gravel surfaces are imperious. The percent impervious is
1.366 ac. / 1.787 ac. = 76.44%. Therefore, Rv = 1.5 x (0.05 + 0.009 x 76.44) _
1.107 inches. The water quality active volume is 1.107" / 12"/ft x 1.787 ac. x 43,560
s.f./ac. = 7,181 cf The proposed active volume of Check Dam "A" = 3,554 cf and the

proposed active volume of Check Dam "B" = 4,704 cf. The proposed total active
volume at the overflow weir elevations is 8.258 cf.
Inlet Protection at Existing Drop Inlets - The two permanent inlet protection
measures will use the natural depression in the center of the site to filter the run-off
from the 0.874 acres of contributing drainage area with 0.783 acres going to the
centrally located drop inlet and 0.091 acres going to the drop inlet located near the
northeast corner of the site. By-passes will flow to the sand filter via the proposed
collection system. Due to the shallowness of the drop inlet receiving the smaller
area, it is assumed that most run-off will bypass it and flow to the curb and gutter
and then onto the sand filter. The inlet protection will be maintained as permanent
measures.
On -site Grass Ditch Receives Runoff Directly from Gravel Area - A 0.476 acre
area at the northwest corner of the site drains overland into an on -site 170 linear
foot grass channel and then into a 125 linear foot roadside grass ditch along
Chappell Loop Road. This will serve as a minimal treatment for total suspended
solids for this 0.476 acre portion of the developed site.
3. Pre -development versus post -development peak flow from site: The peak flow
response to off -site discharges from the site will be reduced significantly for rainfall
events due to improvements to the hydrologic condition and addition of runoff
detaining and infiltration measures. The amount of compacted gravel will be
reduced by approximately 0.810 acres and converted to managed open space
thereby providing more infiltration in the new managed open space areas and less
run-off response. The sand filter basin and two filtration dams combined will
receive run-off from 6.931 acres of the site and have little outflow during the 1-year
event. This assumes using a conservative 2.0 inches/hour infiltration rate for both
the sand filter and the vegetated channel impounded by the two filtration dams.
Since the hydrology is improved and no pre- versus post -peak flow attenuation is
required for permitting, no detailed pre -development versus post -development peak
flow analysis is provided. See the storm drainage map for the pre- and post -
development flow patterns.
4. Hydrologic Soil Groups: The contributing areas are Hydrologic soil group "A" with
the site being mapped predominately as fine sand with moderate to high infiltration
rates (see NRCS map). Most of the site draining to the sand filter is developed and
largely gravel covered and appears to be in fill at the south end of the site.
5. Land Cover Types and Rational Method Coefficients:
Managed open space - (C = 0.30) Vegetated areas, good Hydrologic condition.
Compacted gravel area - (C = 0.85) On -site and off -site areas that are graveled.
Impervious areas - (C = 0.95)
6. Land Cover Types and Curve Numbers for Pre -development and Post -
development Scenarios:
Three types of land cover are utilized for both pre -developed and post -developed
scenarios for on -site and off -site areas, and appropriate curve numbers based on
the Hydrologic Soil Group as summarized below:

Managed open space - (CN = 36) Vegetated areas in the pre -development and
post -development scenarios. Good Hydrologic condition.
Compacted gravel area - (CN = 85) Areas that are graveled.
Impervious areas - (CN = 98)
Reference: "Hydrologic Analysis and Design", McCuen
7. Time of concentration for TR-20 Routing: Segmented flowpaths are outlined in
the report.
8. Starting Tailwater Condition: pipe exits begin at the crown of the pipe or at the
10-year high water elevation of the sand filter as applicable.
9. Rainfall Depth -Duration -Frequency as follows:
24hr storm event
[1-year]
4.00 in
[2-year]
4.80 in
[10-year]
7.50 in
[100-year]
13.00 in
Reference: Rainfall hyetographs from NOAA publication maps for coastal Brunswick
County.
Methodology
Stormwater analyses was conducted with a Hydrocad TR-20 computer model. Peak flows
into and out of sand filter and filter dam basins are calculated by a TR-20 model. Smaller
flows to individual upstream measures are calculated with the rational formula. Erosion
control peak flow calculations (except for sizing the sediment basin) are based on the final
ground cover since this scenario creates a higher peak flow rate.
Storm Water Calculations for Temporary and Permanent Measures
Silt Fence: 1,599 linear feet of silt fence is proposed.
Permanent Surface Sand Filter (Temporary Sediment Basin):
Contributing area when converted to permanent sand filter = 5.144 acres
Contributing area during construction = 5.144 acres
Disturbed area to basin = 1.784 acres
Land cover areas during construction = 1.784 acres disturbed + 3.360 acres compacted
gravel yard
Rational formula 'C'= 1.784/5.144*0.40 + 3.360/5.144*0.85 = 0.694
Tc = 10 min. (assumed), I - 10-year= 6.40 inches/hour
Q-10yr = 0.694 * 6.40 in/hr * 5.144 ac. = 22.85 cfs
Outlet riser will be provided with gravel filter to remove suspended sediments until site is
stabilized.
Volume required = 5.144 acres x 3,600 cf = 18,518 cf
Volume provided = 25,214 cf at elevation 19.50'.

Surface area required = 0.01 x Q10yr = 0.01 x 22.85 cfs = 0.2285 acres or 9,953 square
feet.
Surface area provided= 10.311 square feet at elevation 19.5' (elevation of spillway)
Primary spillway= 3' wide weir in flow splitter box and 12' wide trapezoid grass and TRM
lined earth weir.
Permanent sand filter basin captures and treats the entire 1.5" and 1-year storm event for
total suspended solids.
Channel Calculations
Permanent v-swale diversion to forebay @ 0.8 percent
DA=0.91 ac. (mostly gravel), C=0.85, Tc = 5 min., I - 10-year = 7.5 in/hr. Q 10-year =
0.85*7.5in/hr*0.91 ac.= 5.80 cfs
Side slopes = 3:1 and 8:1, curled wood matting & grass lining, long slope = 0.80%,
Channel depth = 12"
Flow depth = 0.70', V-10yr= 2.17 ft/s.
Shear = T= yds = 62.4 * 0.70' * 0.008 = 0.349 Ib/sf. Grass is stable.
Lining is north American green SC150 or equal. Temporary matting.
Permanent trapezoid diversion to forebay @ 3.7%.
DA= 1.02 ac. (mostly gravel), C= 0.85, Tc= 5 min., I - 10-year = 7.5 in/hr.
Q 10-year= 0.85*7.5in/hr*1.02 ac. = 6.50 cfs
Side slopes = 3:1, long slope = 3.7%, Channel depth = 12"
Flow depth = 0.33', V-10yr= 3.99ft/s.
Shear = T= yds = 62.4 * 0.33' * 0.037 = 0.76 Ib/sf. Grass is stable w/ 8.0 Ib/s.f. turf
reinforcement mat.
Lining is north American green SC250 or equal @ 8.0 Ib/s.f. permanent turf reinforcement
matting.
Permanent grass lined v-swale diversion at sand filter top of slope.
DA= 1.22 ac. (mostly gravel), C= 0.85, Tc= 5 min., I - 10-year= 7.5 in/hr.
Q 10-year= 0.85*7.5in/hr*1.22 ac.= 7.78 cfs
Side slopes = 3:1 & 10:1, long slope = 0.70%, Channel depth = 10"
Flow depth = 0.75', V-10yr= 2.13 ft/s.
Shear = T= yds = 62.4 * 0.75' * 0.007 = 0.328 Ib/sf. Grass is stable.
Permanent rip -rap lined trapezoid diversion at sand filter top of slope.
DA= 1.22 ac. (mostly gravel), C= 0.85, Tc= 5 min., I - 10-year = 7.5 in/hr.
Q 10-year= 0.85*7.5in/hr*1.22 ac.= 7.78 cfs
Riprap section- 3:1, long slope = 15%, Channel depth = 12".
Flow depth = 0.35', V-10yr= 5.37 ft/s.
Shear = T= yds = 62.4 * 0.35' * 0.15 = 3.28 Ib/sf. d50 rip -rap is stable.
Permanent rip -rap diversion into forebay
DA= 2.24 ac. (mostly gravel), C= 0.85, Tc= 5 min., 1 -10-year = 7.5 in/hr.
Q 10-year= 0.85*7.5in/hr*2.24 ac.= 14.28 cfs
Rip -rap section- bottom width= 4', side slopes = 3:1, long slope = 10.0%, Channel depth =
12"
Flow depth = 0.49', V-10yr= 5.49 ft/s.
Shear = T= yds = 62.4 * 0.49' * 0.10 = 3.06 Ib/sf. d50 rip -rap is stable.

Weir Calculations
Permanent weir spillway control section at pond forebay into sand filter
Q 10-year= 20 cfs (TR-20 computer model calculated)
Rip -rap section- bottom width= 12', side slopes = 3:1, long slope = 0.00%, weir depth =
12".
Flow depth = 0.68'. d50 rip -rap = 9", 18" deep with fabric.
Permanent emergency spillway control section out of sand filter
Q 10-year= 15.1 cfs (TR-20 computer model calculated)
Grass Section- bottom width= 12', side slopes = 3:1, long slope = 0.00%, weir depth = 2'.
Flow depth = 0.56', Grass lining w/ 8.0 Ib/s.f. permanent TRM.
Permanent weir in flow splitter manhole junction "I".
Q 10-year= 12.08 cfs (TR-20 computer model calculated)
Concrete Section- bottom width= 4', vertical side slopes, weir depth = 12".
Approach flow depth = 0.95'.
Permanent riprap and gravel check dam weir "A"
Q 10-year= 2.98 cfs (TR-20 computer model calculated)
Riprap Section- bottom width= 5', side slopes = 3:1, weir depth = 12".
Flow depth = 0.33'.
A continuous riprap mat ties into the natural channel to prevent scour.
Permanent riprap and gravel check dam weir "B"
Q 10-year= 4.07 cfs (TR-20 computer model calculated)
Riprap Section- bottom width= 7', side slopes = 3:1, weir depth = 12".
Flow depth = 0.33'.
A continuous riprap mat ties into the natural channel to prevent scour.
RIP -RAP OUTLET PROTECTION
Rip -rap lined exit channel at 18" RCP at flow splitter discharge and headwall at
Ploof Road
Q-10-year = 6.73 CFS, Vo-10-year = 3.80 ft/s.
Line 7 feet of channel, d50 = 9", depth = 18", filter fabric

S&G Prestress site located on USGS quad w/ the symbol "S"
S&G Prestress site located on USGS quad (scaled up)

S&G Prestress site located on NRCS soils map

Elm
Site Solutions, Inc. ELM SITE SOLUTIONS, INC.
Col ='C�-+E
P. O. Box 7607, Raleigh, North Carolina 27624
Telephone [phone] electronic mail: Cellular [phone]
[e-mail]
TRANSMITTAL
r
Via Express Via Hand Delivery Via Mail Via
Delivery electronic
mail
0 .A
To: Linda Lev�rae"and Rhonda Hall
NCDE R
Wilmington Regional Office
127 Cardinal Drive Extension
Wilmington, North Carolina 28405
From: Rusty Norris
Date: April 15, 2011
Project #:
RE: Stormwater Management Plan
WE ARE SENDING:
QUANTITY
DESCRIPTION
4 sets)
Construction Drawings for Permitting
Aeach
Storm Drainage Ma
2 sets
Narrative and Worksheets
1 copy
Financial Responsibility Form
1
Check
FOR YOUR:
Use
Reply
Review/Comments
Information
Files
qApproval
Signature
Return to me (by)
Other
COMMENTS: Please let us know if you have any questions. Thank You.
c — Mr. Joe Beaman
APR 1 8 2�11
�V.

o

%S
FINANCIAL RESPONSIBILITY/OWNERSHIP FORM
SEDIMENTATION POLLUTION CONTROL ACT
No person may initiate any land -disturbing activity on one or more acres as covered by the Act before this
form and an acceptable erosion and sedimentation control plan have been completed and approved by the
Land Quality Section, N.C. Department of Environment and Natural Resources. (Please type or print and, if
the question is not applicable or the e-mail and/or fax information unavailable, place NIA in the blank.)
Part A.
1. Project Name: S&G Prestress Concrete Company Inc
2. Location of land -disturbing activity: County: Brunswick City or Township: Leland
Highway/Street: 9767 Chappell Loop Road Latitude: 34.21 8159N Longitude:-78.01139W
3. Approximate date land -disturbing activity will commence: July 2010
4. Purpose of development (residential, commercial, industrial, institutional, etc.): Industrial NPDES
5. Total acreage disturbed or uncovered (including off -site borrow and waste areas): 2_0
6. Amount of fee enclosed: $130.00 The application fee of $65.00 per acre (rounded up to the
next acre) is assessed without a ceiling amount (Example: a 9-acre application fee is $585).
7. Has an erosion and sediment control plan been filed? Yes No_ Enclosed_
8. Person to contact should erosion and sediment control issues arise during land -disturbing activity:
Name: Joe Beaman, P.G. E-mail Address: ibeaman(o),hesnc.com
Telephone: [phone] Cell*: 919-414-7081 Fax #: [phone]
9. Landowner(s) of Record (attach accompanied page to list additional owners):
S & G Prestress Company
Name
9767 Chappell Loop Road
Current Mailing Address
910 383-6783 N/A .
Telephone Fax Number
Same
Current Street Address
Leland NC 28451
City State Zip City State Zip
10. Deed Book No. 1326 Page No. 1421. 1422, 1423 Provide a copy of the most current deed.
Part B.
Person(s) or firm(s) who are financially responsible for the land -disturbing activity (Provide a
comprehensive list of all responsible parties on an attached sheet):
S & G Prestress Company a wholly owned subsidiary of Florida Rock Industries Inc
Name E-mail Address
P.O. Box 540 2295 Burnett Boulevard
Current Mailing Address Current Street Address
Wilmington NC 28402-0540 Wilmington NC 28402-0540
City State Zip City State Zip
Telephone:[phone] Fax Number 910 763-2064 — -
APR 1 S 2U11

2. (a) If the Financially Responsible Party is not a resident of North Carolina, give name and street address
of the designated North Carolina Agent:
Florida Rock Industries Inc. a wholly owned subsidiary of Vulcan Materials Company
Na me E-mail Address
Current
Jacksonville A 32201 Jacksonville FI 32206
City State Zip City State Zip
Telephone: [phone] Fax Number: 904 791.1811
(b) If the Financially Responsible Party is a Partnership or other person engaging in business under an
assumed name, attach a copy of the Certificate of Assumed Name. If the Financially Responsible
Party is a Corporation, give name and street address of the Registered Agent:
Name of Registered Agent E-mail Address
Current Mailing Address
Current Street Address
City State Zip City State Zip
Fax Number.
The above information is true and correct to the best of my knowledge and belief and was provided
by me under oath (This form must be signed by the Financially Responsible Person if an individual
or his attorney -in -fact, or if not an individual, by an officer, director, partner, or registered agent with
the authority to execute instruments for the Financially Responsible Person). I agree to provide
corrected information should there be any change in the information provided herein.
Thompson S. Baker II President
Type or print name Title or Authority
//%J I )JC 6-2Q-10
Sign t (e Date
I, Y f J. �VO_26�4C%&; , a Notary Public of the County of D�Lvcj
State of Ftpci&ram, hereby certify that-1'appeared
personally before me this day and being duly sworn acknowledged that the above form was
executed by him.
Witness my hand and notarial seal, this a 9 day of Zu\e.. .20 10
Vio'LL; %f f�111�70riL(1
Notary
Seal
My commission expires<a��aO11
� eaz�a � APR 1 8 Z011
�� t

M
Site Solutions, Inc. ELM SITE SOLUTIONS, INC.
P. O. Box 7607, Raleigh, North Carolina 27624
Telephone [phone] electronic mail: Cellular [phone]
[e-mail]
x Via Express
Delivery
To: Linda Lewis
TRANSMITTAL
0 Via Hand Delivery E
Via Mail
NGUENR
Wilmington Regional Office
127 Cardinal Drive Extension
Wilmington, North Carolina 28405
From: Rusty Norris
Date: July 21, 2010
Project #:
RE: I Stormwater Management Plan
WE ARE SENDING:
Via
electronic
mail
QUANTITY
DESCRIPTION
2 sets
Construction Drawings for Permitting
2 sets
Narrative and Worksheets
1 copy
Financial Responsibility Form and Check Previously Submitted
FOR YOUR:
Use
Reply
Review/Comments
Information
Files
qApproval
Signature
Return to me (by)
Other
COMMENTS: Please let us know if you have any questions. Thank You
c — Mr. Joe Beaman

FINANCIAL RESPONSIBILITY/OWNERSHIP FORM
. SEDIMENTATION POLLUTION CONTROL ACT
No person may:initiate any land -disturbing activity on one or more acres as covered by the Act before this
form and an acceptable: erosion and sedimentation control plan have been completed and approved by the
Land Quality. Section,. N.C. Department of Environment arid Natural Resourccsi. (Please typd, or print and, if
the question is not applicable or the e-mail and/or fax information unavailable, pl . ace N/A imthe blank.)
Part.A
1 Project Name: S&G Prestress Concrete Company, Inc.
2. Location of larid-chstur6ing activity: County;.Brunswick C - ity, or Township: 'Leland
HighwayiStreet: - 9767,C happell Loop -Road Latitude: 34.21 al 59N Longitude: . 78:01 1 139W
Approximate date lan6-cfisturbing activi I t I y'willcommence: July-2010
4, Purpose of development (residential..corrimercia 1, indystrialinstitU tic nal,, etc:): Industrial NPDES
6. Total acreage disturbed or uncovered (including, off -site borrow.and waste:areas)': 2.0
6. Amount of fee enclosed: S130. - 00 The application fee of,$65.00 per acre (rounded up to the
;next acre) is assessed without•aceiling amount (Example::a 9-acre application fee is, $585):
7 Has an, erosion1 and sed.im.ent,controf plan been filed? Yes No-- Enclosed
& Person to contact should erosiomand sediment control issues ariSerduring land7disturbing activity:
Name: Joe Beaman. P.G. E-mail Address: ibeam6h(),hesnc.com
Telephone: [phone] Cefl,#:, 919-414-7081 Fax #: [phone]
9: Landowner(s) of Record (attach accompanied page to.list additional owners),
S &.'G Prestress. Company 910 383-6783 N/A_
Name Telephone Fax Number
976T.Chapl3elI L66lp Road Same
Current Mailin4 Address Current,Street'.Address,
Leland; NC 28451
City State Zip City State Zip,
10. Deed',Book.Nd. 1326 Page No., , 142f. , 1422; 1423 Pfovidea copy of the most current deed.
Pairit B.
1., Person(s) or firm(s): who are financially, responsible for. the land -disturbing activity (Provide a'
comprehensive list of all responsible parties on an attached sheet):
SA G;Prestress Company a wholly owned subsidiary of Florida Rock Industries, Inc.
Name E-mail Address
P.O. Box,540 2295 Burnett Boulevard!
Current Mailing Address Current Street Address.
Wilmington. NC 28462-0540 Wilmington NC 28402-0540
City . . . ­ -1 . State Zip, City State Zip
Teleptione:910 763-7702 Fax Number 910 763-2064

2. (a) If the Financially Responsible Party is not a resident of North Carolina, give name and street address
of the designated North Carolina Agent:
Florida Rock Industries. Inc. a wholly owned subsidiary of Vulcan Materials Company
Name E-mail Address
Address
Address
Jacksonville FI 32201 Jacksonville FI 32206
City State Zip City State Zip
Telephone:. [phone] Fax Number: 904 791.1811
(b) If the Financially Responsible Party is a Partnership or other person engaging in business under an
assumed name, attach a copy of the Certificate of Assumed Name. if the Financially Responsible
Party is a Corporation, give name and streetaddress ofthe Registered Agent:
Name of Registered Agent E-mail Address
Current Mailing Address Current Street,Address
State Zip City
Fax Number:
The above information is true and correct to the best of my knowledge and belief and was provided
by me under oath (This form must be signed by the Financially Responsible Person if an'ihdividual
or his attorney -in -fact; or if not an individual, by an.officer, director, partner; or registered agent with
the authority to execute instruments for the Financially Responsible Person). I,agree to provide
corrected information should there be any change in the'information provided herein.
Thompson S. Baker II President
Type or print name Title or Authority
Sig
Date
I, V I C� tC F 'V • 1�4c-zrr . rz—t f aNotary Public of the County of "bu%ki
State of Roci&t, hereby certify that?.bQ.h-c. appeared
personally before me this day and being duly- sworn ,acknowledged that the above form was
executed by him.
Witness my hand and notarial seal; this q day of 3�A!NeL 20 (0
Seal
yI ctu :W t�l t�,driGtt Ses
Notarykl
My commission expires 25,01011

I�'1.�
g"�'�J ` FIFLORIDA ROCK_'DIVISION CHECK NO.
1060051177
••�� '$mil POST OFwFICE BOX 4667 'JACKSONVILLE' Ff ORIDA 32201
CompanyPHONEj1 B00 h62-0R13 r h.,
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VOID AFTER 90 DAYS ,. ��srHu�d�ed�ThIrty�D"'ot�a�sAnd00rC�ents* 4*"" *
II III I ICI I I� I I I �IYI i'I ' ° 'r DATE � CHECK AMOUNT
, . .
13 JUL-10 l , �, *».*130:00
xthCaro)Tna Deptyof�Env,oment and N a,` {� '- -
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FLORID- ROCK`DIVI510N—�----_T_`---D—nTE 13-JUL 1D ' racEvf
'POST OFFICE BOX 4667 JACKSONVILLE, FLORIDA 32201 CHECK NUMBERr 1060051177
INVOICE DATE'
29 JUN-10
Dept.t
of-EnviromeriP and SUPPLIER NUMBER; 14295'
,DESCRIPTION- DISCOUNT
'COMPANY: 0161 i
AMOUNT I
0.00., 130.06
S
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11IE ATTORNI?Y PRFTARING THIS INS`I'RUNIF,N`f
liAS MADE NO RECORD SEE: ClI OR TITLE:
iEXA.,MI:NATION AS70 TIM PROPERTY HEREIN
DI,:SCIURE>D. UNL:IE.S'S THESAiNIL IS SHOWN
BY HIS %VR1TT1_,_NAND SIGNED CERTIFIC A`F.
hrunswick County —Register of Deeds
Robert J. Robinson
Inst #23782 Book 1326Page 1421
08/31/1999 09:23ain Recf
Mail after recording,, to: S & G Prestress Comp hy; P. O. Box i4-0, Wilmington, NC:28102
This instrwrient was prepated by. Jackson, A9ills & Carley, P.A., 5710 Oleander Drive, Suite 11_1, Wilmington.
NC 28403
Brief ileseriptiun fOr the Indcxt 9.2 acres, portion of tract,descri,bcd,in Book'296 at Page 628
08/31/1999
Parcel No: $200.00 5
TH
NaSCA"E OF NOR"HCIROCINA 0oa� es are
Real
COUNTY, OF BRUNSWICK GENERAL WARRAN"rY DEED
THIS DEED made thtti `�`rI'dav of u, 1- 1999 by anal between
G K ENTERPRISES, INC.; a N'orlh Carolina c rporation, hereafter GRAtN'"I'Olt, and
S � G.pizLS'TRESS COMPANY, a North,C arolina corporation, hereafter GRANTEE
The dcsivnation .Grantor and Grandee as used herein. ~hall inclucle °said parties, their
h,eirs,,suecessots, and assigns, and shall include'singular, plural, masculine', feminine or
neutu as regtiii'cd by eol'ttest.
WITNESSETI-I:
That the Grantor,; for a va cable considerat on,paitl by the Grantee, the receipt of Wliich
is herebv acicnoivledgcd, has and by these presents does grant, bargain, sell and.eonvey
unto the Grantee in fee simple, all that certain lot or parcel of land 'Situated in Brunswick
COLUlt V. North Carolina and more particularly described as follows:
BUNG ALL OF THE PRORE10-Y DE•SCUIED ON EXHIBIT "W!
A"ITACHED. HERETO, MADE A PtvZr HEREOF AND
INCORPORATED HEREIN BY REFERENCE.
"fhc pro pertphereina ove described )xas acquired by Grantor by instrument recorded
in the Brunswick GOiulty Registry:
TO-I-LWL'- AND TO HOLD the aforesaid lot or parcel.of land.and all privileges amd
appurtenances thereto belonging to the Grantee in fee simple..
And the Grantor covenants with the Grantee, 'tharGrantor is seized of the premises in
fce simple, has the riklit to Convevtihe same in fee simple. that. title is markeaahle ]:nd

INT 1,VITNI SS bVIAEREOF, the Grantor has hereunto set his hand ind seal, or if
C:Orporat,c.., li�ls Caused this instrujilentto be signed in its corporace.name by its duly
authorized officers u)d iLS SCIII to be hereunto affixed by aUdloritv of its: Board of
Directors: the dayancl Year.first. above NvriLLCII.
G K ENTEFTMSES, INC.
AXTEST
BY:
Secretary
(AFFIM CORWORATIE,SEAL)
STATE 01.' NIOXIT-1 CJUMLANA
!COUNTY 01"-N, F V\I�' I-MiXOVER
w
Tnst # 23782 WIpk 1326Page: .1422
11-i a Notan, Public of the Couhtv ,of
MIL
and State aforesaid, Lo herebyCCftifV that 1�1j DR S
pertiofiallY came before: me this day and acImowledged that 'he/shc is
SecreLal�of G K.ENTERPRISES, INC, and diaL, by autl ioritV duly given and as the:
act ofthe"corpor.-ation, the foregoing I'llStRIII'lellt NWISsigpecl in its name by its
Pnesiciciu, sealed with its coirljora . t . c seal, and attested bvsh.-4z f/herself as its
_VVITNESS my hand alld notarial seal, this` the
Cav or
9 -9.
9
NOUAT Public
My Commission Expiresrb
-
J HE
CIO 4
(:AFFIX NOTARIAL SLAL)
9 L

FX1-1113IT A
Being ;ill of than read property located ill "Cotvti Creek Township, Bruns,.trick County,
North Carolina described as follows:
BEGINNING at a penult in the Northwestern line. of State Road Number 1524 (60 COOL
right. of waY); said point tieing South 34 degrees 26 minutes 1,9 seconds East, 644.50 feet
from the intusect.ion of the Northwestern line ofsaid State Road Ntmlbcr 1524 wnli
the Southeastern tine of Old U.S. Highway Number 17, now known as State Road
Number 1551, (60 loot right of way), said intersection being 1.2 miles Westtcardlylront
the intersection of said State Road Number 1551'and N.C: Highway, Number-133;said
beginning point being North 'Carolina Grid Coordinate North 172,135.58 and East
`) 299,2 16. 13. Said beginning point beirig further described as benur lit the: dividing NILe
of the propem, of Lincoln Development Company, Inc., as recorded in Book,296 atIlage
62, of the B uns`wick County'iRegistry, and the property of James Ivlallctt,.as recorded
in -Book (:Cat Pagc 390 ofsaid Registry; running thcncc from said beginninu.Point, with
and along the Northwestern line ofsaid State Road Number 1524, South 34 degrees 26
minutes 19 seconds List, 229.22 feet to the in ersectiotr of said northwestern line ofsaid
$tau.c.Road.Number 1524 with the Northern line of Ploof Road (SO foot right: of way);
thence with and along the Northern line ofsaid Ploof-Road South 55 'degrees ,32
minutes I I seconds West 1,0.43.8 l feet to a Point -in a ditch. Said line of said. Ploof
Road crossing the lands formerly owned by Nelson Shaw, as recorded in Book CC at
Page 3�57, of said RegiSLry, and the land Formerly owned, by Andrew Williams as
recorded in Book CC at Page 38S of said Regisu-y; thence along the cent,& line ofsaid'
ditch North 34 degnes 27 minutes'49 seconds Nest, 4100.00 feet to a point. Said point
being in the. dig%iding line betwee,rp Lincoln Development Company, Inc. and the land
-now or fortuerly owned by Simon Small, as,recorded in Book CC at Page 194 of said
Rcgistrv; thence along said dividing line of Lincoln Development. Company, Inc. and
Simon Small North 55.degrees 32 minutes 1 I seconds,East S4=1.00 feet to a point in the
southern line of the lands now or'formerly 'owned by James Mullett, as recorded in Boole
CC, at Page 390, of said Registry; thence with and along said tilallett line South 83
degrees 50 minutes t 9 seconds East; 262.99 feet to the point of beginning. Containing
9.-20 acres, mire or less, and, being a portion of the property ci,nveved to Lincoln
Developnre�t Company, Inc. by Lincoln Construction Company, Inc., as recorded- in
Book 296 at Page 628 of said Bruns%�,2ck County Registry according tc> the map, thereof
duly recorded in iNlap Cabinet "L" at Page 130 of the Brunswick County Registry:
Inst # 23782 Book 1326Page: 14 23

f
,J //
an

+r:
Site Solutions, Inc ELM SITE SOLUTIONS, INC.
P. O. Box 7607, Raleigh, North Carolina 27624
Telephone [phone] electronic mail: Cellular [phone]
[e-mail]
x Via Express
Delivery
TRANSMITTAL
Via Hand Delivery E
Via Mail
To:
Linda Lewis
NCDENR
Wilmington Regional Office
127 Cardinal Drive Extension
Wilmington, North Carolina 28405
From:
Rusty Norris
Date:
July 21, 2010
Project #:
RE: Stormwater Management Plan
WE ARE SENDING:
Via
electronic
mail
QUANTITY
DESCRIPTION
2 sets
Construction Drawings for Permitting
2 sets
Narrative and Worksheets
1 copy
Financial Responsibility Form and Check Previously Submitted
FOR YOUR:
Use
Reply
Review/Comments
Information
Files
X Approval
Signature
Return to me (by)
Other
COMMENTS: Please let us know if you have anv ouestions. Thank You
c — Mr. Joe Beaman RECEIVED
JUL 2 2 2010
BY:

Narrative Report
Stormwater Management Plan
Prepared For:
S&G Prestress Company
9767 Chappell Loop Road
Leland, North Carolina 28451
PIN:219720818887
July 20, 2010
8f:rm
Site Solutions, Inc.
ELM Site Solutions, Inc.
P. O. Box 97607
Raleigh, North Carolina 27624

I. Narrative
Summary of Existing Conditions
The existing project development site is located in the Cape Fear River basin in Brunswick
County on a +/- 9.19 acre parcel. The property is currently being used for outdoor
manufacturing of pre -stressed concrete components. The site is zoned industrial and has
been in operation since the 1970's. The site has an NPDES permit (#070116). The
property drains to a tributary of Jackey's Creek, which has a surface water classification of
C, SW. The site's west property boundary is adjacent to a stream mapped as intermittent
on the USES quad and USDA soils maps. The stream has a 30-foot buffer that intrudes
onto the prefect site. The property is not located within an incorporated area. Therefore,
sedimentation and erosion control permitting will be applied for at the Wilmington Regional
Office of the NCDENR
The site soils are listed as HSG "A" and are predominately Lo (Leon Fine Sand) and On
(Onslow Fine Sandy Loam). The existing site hydrologic condition is characterized as
0.465 acre impervious, 7.385 acres compacted gravel and 1.340 acres managed open
space. In addition to the stream along the west boundary, the site is surrounded by a
large on -site wooded channel to the north and off -site roadside ditches to the east and
south. The site drains via overland flow to adjacent sides of the site with the exception of
three specific pipe conveyances. Site drainage ultimately discharges through a single 48"
concrete pipe culvert crossing Ploof Road. There are no offsite run-on contributions to the
built upon areas of the site. The large on -site wooded ditch bordering the north side of the
property has a. very flat long slope of approximately 0.24% and receives a small amount of
run-on from off -site sources.
Summary of Proposed Conditions
The work proposed generally includes installing a permanent stormwater collection and
treatment system for compliance with the NPDES permit condition for maintaining a
turbidity threshold of 50 NTU's in the runoff from the site. The stormwater collection
system is a series of pipes, channels and check dams that route a majority of the
developed site to an open sand filter. The sand filter is sized to capture the 1-year storm
and provide treatment for total suspended solids for 7.865 acres of the site's drainage
area. On -site developed areas are routed to the sand filter with the exception of a 0.476
acre area rear Chappell Loop Road that drains overland to the road side ditch system
along Chappell Loop and Ploof Roads. The total disturbed area both on -site and off -site is
2.10 ac. The Iota[ area to be revegetated is 0.900 ac.
The open sand filter will also serve as a temporary sediment basin during installation of
the storm drainage system and will be converted over to the permanent sand filter function
once the u^stream disturbed areas are stabilized. The temporary sediment basin will
utilize a per orated 8" PVC riser and gravel filter to remove sediment from the discharge
water.
II. Base Assumptions
Handling of Contributing Off -site Drainage Areas: There is a small off -site area of
0.112 ac. a'ong a portion of the long north boundary that creates run-on into the existing

wooded channel. A diversion ditch is proposed to route potential run-on below and away
from the sand filter.
Capture and Treatment of the 1.5 inches of Rainfall (Water Quality) event and the 1-
Year evert: The open sand filter and two stone and gravel check dams capture the 1.5
inch rainfall design storm and the 1-year event and treat for suspended solids to achieve a
discharge turbidity of 50 NTU's. The 2-year event is captured almost in its entirety with
only a 1.42 CFS peak discharge from the sand filter basin. A 0.476 acre on -site gravel
area near Chappell Loop Road will bypass the sand filter, but will enter a series of grass
ditches that have had their drainage areas diminished significantly due to the new piping
and diverting of the existing overland flow to the sand filter basin. The existing grass
ditches along Ploof Road and Chappell Loop Road will have increased water treatment
capability due to the diverting of site generated runoff. The long flowpath of the on -site
area that bypasses the sand filter will receive significant reduction in turbidity when it joins
the remaining on -site generated flows at the proposed endwall at Ploof Road.
Pre -development versus Post -development Peak Flow from the Site: The hydrologic
condition will be improved in several ways that will reduce off -site peak flows in the post
development scenario. The amount of compacted gravel will be reduced by 0.61 acres
and converted to manage open space so there will be more infiltration in the new
managed open space areas and less runoff response. A large surface sand filter basin
and two rock check dams is designed to capture runoff from the site (with the exception of
the aforementioned 0.476 acres) during the 1.5-inch and 1-year storm. The 2-year event is
largely atter uated and the 10-year storm is attenuated by 13 CFS.
Since no impervious area is proposed, the hydrology is improved, and the sand filter basin
captures the majority of the site, no detailed predevelopment peak flow is calculated. See
the attached Storm Drainage Map for the pre -development flow patterns and the 10-year
peak flows from the two functioning pipe culverts that discharge to the Ploof Road ditch.
Hydrolog;c Soil Groups: The contributing areas are all Hydrologic soil group "A" with the
site being mapped predominately as fine sand with moderate to high infiltration rates (see
NRCS map below). Most of the site draining to the sand filter is developed and largely
grave! covered and appears to be in fill to an unknown degree.
Land Cover Types and Rational Coefficients:
Managed open space- (C=0.30) Vegetated areas. Good Hydrologic condition.
Comoa cted gravel area- (C=85) Onsite and offsite areas that are graveled.
impervious areas- (C= 95)
Land Cover Types and CN's for Pre -development and Post -development Scenarios:
Three types of land cover are utilized for both pre -developed and post -developed
scenarios `or on -site and off -site areas and appropriate curve numbers based on the
Hydrologic So!I Group "HSG" " are calculated in each sub -area as follows:

For HSG 'A
Managed open space- (CN=36) Vegetated areas in the pre -development and post -
development scenarios. Good Hydrologic condition.
Compacted' gravel area- (CN=80) Onsite and offsite areas that are graveled.
Impervious areas- (CN= 98)
Reference: "hydrologic Analysis and Design", McCuen
Time of concentration for TR-20 Routing: Time of concentrations are taken to be 5
minutes due to the nature of the site.
Starting Tailwater Condition: For all pipe, exits begins at the crown of the pipe or at the
10-year high water elevation of the sand filter as applicable.
Rainfall Depth -Duration -Frequency as follows:
24-hour storm event
11 yr]
4.00 in
[2 yr]
4.80 in
[10 yr]
7.50 in
[100 yr]
13.00 in
Reference: Rainfall hyetographs from NOAA publication maps for coastal Brunswick
County.
III. Methodology
Stormwater analyses conducted with Hydrocad TR-20 computer model. Peak flows into
and out of sand filter are calculated by a TR-20 model. Smaller flows to individual
upstream measures are calculated with the rational formula. Erosion control peak flow
calculations (except for sizing the sediment basin) are based on the final ground cover as
this scenario creates a higher peak flow rate.
IV. Stormwater Calculations for Temporary and Permanent Measures
Silt Fence
1,850 linear feet of silt fence is proposed.
Silt Fence Cutlet (Located at the southeast corner of site near Ploof Road
Contributing area = 0.615 acres (0.498 acre disturbed, 0.117 acre compacted gravel)
Rational 'c' = 0.498/0.615*0.40 + 0.117/0.615*0.85 = 0.486
Te = 5 minute (assumed), 1-10 year= 7.50 in/hr
Q-10 year = 0.486 * 7.50 in/hr * 0.615 ac. = 2.24 CFS
Required Volume behind overflow weir = 3,600 c.f. * 0.498 ac. = 1,793 c.f.
A 1,793 c.f. excavated pit will be provided in front of the outlet and calculated to the weir
elevation of 19.5'. Weir length= 5'.

Permanent 3!1rface Sand Filter (Temporary Sediment Basin)
Contributing area when converted to permanent sand filter = 7.865 acres
Contributing area during construction = 0.809 acres
Disturbed area = 0.503 ac
Land cover areas during construction = 0.503 acre disturbed + 0.306 acre compacted
gravel yard.
Rational 'c' = 0.503/0.809*0.40 + 0.306/0.809*0.85 = 0.570
Tc = 5 min. (assumed), 1-10 year= 7.50 in/hr
Q-10 year = 0.570 * 7.50 in/hr * 0.809 ac. = 3.46 CFS
Outlet riser will be provided with gravel filter to remove suspended sediments.
Volume required = 0.503 ac. x 3,600 c.f.= 1,811 c.f.
Volume provided = 7,116 c.f. at elev. 165.
Surface area required = 0.01 x Q10yr = 0.01 x 3.46 CFS = 0.0346 ac. or 1,507 vs.
Surface area provided= 11,040 square feet at elevation 19.2'. (elevation of spillway)
Primary spillway= 4' wide weir in flow splitter box and 10' wide trapezoid grass and TRM
lined earth weir.
Permanent sand filter basin captures and treats the entire 1.5" and 1 year storm event for
total suspended solids.
Channel Calculations
Permanent Diversion to catch basin "H" (adjacent to berm flowing south)
Drainage Area (DA) = 0.33 ac. (all gravel), C= 0.85, Tc= 5 min., 1 10 year= 7.5 in/hr. Q 10-
year= 0.85*..5in/hr*0.33 ac. = 2.10 CFS
Side slopes = 3:1 and 10:1, gravel lining, long slope = 1.0%, Channel depth = 6"
Flow depth = 0.50', V-10 year= 1.46 ft/s.
Shear = T= yds = 62.4 * 0.50' ' 0.01 = 0.312 Ib/sf. Gravel is stable.
Permanent Diversion bypassing offsite run-on from pond inlet channel
DA= 0.112 ac. (managed open space), C= 0.30, Tc= 5 min., 1 10 year= 7.5 in/hr.
Q 10 year= 0.30*7.5in/hr*0.112 ac. = 0.25 CFS
Side slopes = 3:1, grass lining, long slope = 1.0%, Channel depth = 6"
Flow depth = n.28', V-10 year= 1.11ft/s.
Shear = T= yds = 62.4 * 0.28' * 0.01 = 0.17 Ib/sf. Grass is stable.
Permanent Aversion at Forebay top of slope (adjacent to berm flowing west)
DA= 0.353 ac. (0.302 gravel + 0.051 mos), C= 0.77, Tc= 5 min., 1 10 year= 7.5 in/hr.
Q 10 year= 0.77*7.5in/hr*0.353 ac.= 2.04 CFS
Gravel Section- side slopes = 3:1 and 10: 1, long slope = 1.0%, Channel depth = 6"
Flow depth = 0.48', V-10 year= 1.42 ft/s.
Shear = T= yds = 62.4 * 0.48' * 0.01 = 0.300 Ib/sf. Gravel is stable.
Ripra? section- 3:1, long slope = 13.0%, Channel depth = 6", d50= 6".
Flow dept'� = 0.43', V-10 year= 3.71 ft/s.
Shear = T= yds = 62.4 * 0.438' * 0.13 = 3.55 Ib/sf. Hand laid riprap w/ fabric is stable.
Permanent Diversion into Forebay
DA= 2.250 arc. (1.688 gravel + 0.103 impervious + 0.459 mos), C= 0.74, Tc= 5 min., 1 10
yea- 7.5'n/hr.

Q 10 year= 0.74*7.5in/hr*2.25 ac.= 12.49 CFS
Grass Section- bottom width= 4', side slopes = 3:1, long slope = 1.0%, Channel depth =
12"
Flow depth. = 0.68', V-10 year= 3.10 ft/s.
Shear = T= yds = 62.4 * 0.61' * 0.01 = 0.381 Ib/sf. Grass is stable.
Riprap section- 3:1, long slope = 9.0%, Channel depth = 12", d50= 9".
Flow depth = 0.47', V-10 year= 5.06 ft/s.
Shear = T= yds = 62.4 * 0.47' * 0.09 = 2.64 Ib/sf. Hand laid riprap is stable.
Permanent'^.ergency Spillway Channel Out for Pond Forebay
Q 10 year= ' 7.13 CFS (TR-20 computer model calculated)
Grass Sec,i^n- bottom width= 10', side slopes = 3:1, long slope = 1.5%, Channel depth =
12"
Flow depth = 0.46', V-10 year= 3.32 ft/s.
Shear = T= yds = 62.4 * 0.46' * 0.015 = 0.43 Ib/sf. Grass is stable.
Q 100 year= 54.8 CFS (TR-20 computer model calculated)
Flow depth = 0.89', V-10 year= 4.88 ft/s.
Shear = T= yds = 62.4 * 0.89' * 0.015 = 0.83 Ib/sf. Grass is stable.
Turf reinforcement matting rated at 2.0 Ib/sf is specified as a permanent liner w/ grass
cover.
Weir Calcut!a`ions
Permanent=mergency Spillway Control Section Out for Pond Forebay
Q 10 yea— 17.13 CFS (TR-20 computer model calculated)
Grass Section- bottom width= 10', side slopes = 3:1, long slope = 0.00%, weir depth =
2.0'.
Approach `:low depth = 0.65', V-10 year= 2.40 ft/s.
Q 100 year= 54.8 CFS (TR-20 computer model calculated)
Flow depth = ' .25' (flow elev. 20.45', top of dam elev. 21.50'), V-10 year= 3.25 ft/s.
Grass is sta.b!e. Turf reinforcement matting rated at 2.0 Ib/sf is specified as a permanent
liner w/ crass cover.
Permanent Forebay Spillway Control Section Out for Pond Forebay into Sand Filter
Q 10 year= 32.0 CFS (TR-20 computer model calculated)
Riprap Section- bottom width= 12', side slopes = 3:1, long slope = 0.00%, weir depth =
12".
Approach flow depth = 0.78', V-10 year= 2.65 ft/s.
Riprap is stable. A continuous apron of riprap stone connects weir to sand bed to minimize
scour pctential.
Permanent'Ateir in Flow Splitter Manhole Junction "I".
Q 10 year= 12.08 CFS (TR-20 computer model calculated)
Concrete Section- bottom width= 4', vertical side slopes, weir depth = 12".
Approach f!o,.v depth = 0.95'.
Permanent i'!r-Rap and Gravel Check Dam Weir "A"
DA = 0.847 ac. (0.617 ac. gravel + 0.197 ac. mos + 0.033 ac. impervious), Rat C= 0.73, 1
10 yr= 7.50/hr
Q 10 year= 4.64 CFS

Riprap Section- bottom width= 5', side slopes = 3:1, weir depth = 12".
Approach flow depth = 0.40'.
A continuous riprap mat ties into the natural channel to prevent scour.
Permanent 17"o-Rap and Gravel Check Dam Weir "B"
DA = 1,747 ac. (1.260 ac. gravel + 0.415 ac. mos + 0.072 ac. impervious), Rat C= 0.73
10 yr= 7.50 in/hr
Q 10 year= 9.56 CFS
Riprap Section- bottom width= 7', side slopes = 3:1, weir depth = 12".
Approach flow depth = 0.53'.
A continuous ri?rap mat ties into the natural channel to prevent scour.
Culvert >Icu'ations
30" RCP ;n.".owing to CB-H
DA= 3,848 ac.. (3.420 gravel + 0.428 impervious), C= 0.86, Tc= 5.0 min., 1 10 year= 7.50
in/hr
Q 10 year= C'I`A= 0.86 ' 7.50 in/.hr ` 3.848 ac. = 24.8 CFS
Tailwater take:-, , to be overflow elevation of weir 19.35'.
Computed �'W = 20.72', HW/D=1.24 due to backwater effect of pond
Upstream C3-G rim elev.= 22.40'
24" RCP in`.l^wing to CB-G
DA= 2.868 a.c_ (2.448 gravel + 0.420 imperv.), C= 0.87, Tc= 5.0 min., 110yr= 7.50 in/hr
Q 10 year = C"*A= 0.87 . 7.50 in/.hr ` 2.868 ac. = 18.71 cfs
Tailwater calc_ lated at 20.72'.
Computed HW = 22.09', HW/D=1.82 due to backwater effect of pond
Upstream CB-'- rim elev.= 23.70'
24" RCP Cutrlowing from Manhole Junction J
This pipe receives split flow from weir in manhole hole junction I.
10yr peak flow is 12.08 cfs (TR-20 computer model calculated)
Tailwater assumed at crown of pipe at endwall at Ploof Road - elev. 14.50'
Computed! W = 15.79', HW/D=0.95.
RIP -RAP CUTLET PROTECTION
Rip.ran exit channel at 24" RCP at Endwall at Ploof Road
Q-1 OYR = 12.58 CFS, Vo-10YR = 4.01 CFS
PROVIDE 14 L.F. RIP -RAP LINING OF RECEIVING CHANNEL, d50 = 6", depth = 12",
filter fabric.

- V t. 1, , L

T

AUNorth Carolina Department of Environment and Natural Resources
NCDENR ONE -STOP MEETING REQUEST
FILL-IN all the information below. FAX or Email the completed form to the Coordinator
• Asheville Region -Alison Davidson 828-196-4698; alison.davidsonanncdenr.gov
• FayettevillelRaleigh Region - David Lee 919-791.4203; david.leeClancdenr.gov
• MooresvillelWinston Salem - Patrick Grogan 704-663-3772; patrick.grogan(a)ncdenrgov
• Washington Region - Lyn Hardison 252-946-9215, lyn.hardison(@.ncdencgov
• Wilmington Region - Cameron Weaver 910-350-2004; cameron.weaver(dncdenr aov
Project Name: S&G Prestress Concrete Company, Inc. County: Brunswick
Applicant: S&G Prestress Concrete Company Company:
Address: 9767 Chapel Loop Road City: Leland State: NC Zip: 28451
Phone: Fax: Email:
Physical Location of Project: same as above
Engineer/Consultant: Roland Norris/Joseph Beaman Company: ELM Site Solutions/Highlands Environmental
Address: P.O. Box 97607 City: Raleigh State: NC Zip: 27624
Phone: [phone] Fax: Email: RNorris ELMSiteSolutions.com; JBeaman HESNC.com
Please provide a DETAILED project narrative, pdf site plan and a vicinity map with road names along with this Request form.
See Attached
The project narrative should include the following when available:.
Existing Conditions- List of existing permits, previous project name(s) or owner name(s), existing compliance or pollution incidents, current
conditions or development on site, size of tract, streams or wetlands on site', stream name and classification, historical significance of
property, seasonal high water table elevation, riparian buffers, areas of environmental concern, setbacks
Proposed Full scope of project with development phase plan, acreage to be disturbed, wetlands to be disturbed, waste treatment & water
supply proposed, soils report availability, % impervious surface, stormwater treatment and number of bmps, public or private funding.
'Relative To Wetlands — Federal and coastal wetlands must be delineated by a US Army Corps Regulatory Official, Coastal Management
Field Rep or a qualified environmental consultant prior to undertaking work such as filling, excavating or land clearing. The delineations
must be approved by the US Army Corps of Engineers (USACE) and/or the Division of Coastal Management. Wetland delineations are
valid for a period not to exceed five years from date of USACE approval.
For the One Stop Meeting, it is best to provide a list of questions and topics of concern. It is helpful to know what you hope to
gain from the meeting. Please have thoughts and presentations organized as much as possible to make the best use of time.
Agencies Involved: Check all agencies that may be involved with project:
❑ Marine Fisheries ❑ National Marine Fisheries ❑ U.S. Fish & Wildlife ❑ Wildlife Resources
❑ Coastal Management X Land Resources X U.S. Army Corps of Engineers ❑ Shellfish Sanitation
❑ Aquifer Protection ❑ Water Quality: (❑ Stormwater, X 401/buffer, X NPDES) ❑ Public Water Supply
❑ Air Quality ❑ Solid Waste ❑ UST ❑ Other_ ❑ Other_ ❑ Other_
NCDENR One Stop Meeting
And 2nng

Narrative Report
Stormwater Management Plan
Prepared For:
S&G Prestress Company
9767 Chappell Loop Road
Leland, North Carolina 28451
PIN:219720818887
July 20, 2010
Em
Site Solutions, Inc.
ELM Site Solutions, Inc.
P. O. Box 97607
Raleigh, North Carolina 27624

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I. Narrative
Summary of Existing Conditions
The existing project development site is located in the Cape Fear River basin in Brunswick
County on a +/- 9.19 acre parcel. The property is currently being used for outdoor
manufacturing of pre -stressed concrete components. The site is zoned industrial and has
been in operation since the 1970's. The site has an NPDES permit (#070116). The
property drains to a tributary of Jackey's Creek, which has a surface water classification of
C, SW. The site's west property boundary is adjacent to a stream mapped as intermittent
on the USGS quad and USDA soils maps. The stream has a 30-foot buffer that intrudes
onto the project site. The property is not located within an incorporated area. Therefore,
sedimentation and erosion control permitting will be applied for at the Wilmington Regional
Office of the NCDENR
The site soils are listed as HSG "A" and are predominately Lo (Leon Fine Sand) and On
(Onslow Fine Sandy Loam). The existing site hydrologic condition is characterized as
0.465 acre impervious, 7.385 acres compacted gravel and 1.340 acres managed open
space. In addition to the stream along the west boundary, the site is surrounded by a
large on -site wooded channel to the north and off -site roadside ditches to the east and
south. The site drains via overland flow to adjacent sides of the site with the exception of
three specific pipe conveyances. Site drainage ultimately discharges through a single 48"
concrete pipe culvert crossing Ploof Road. There are no offsite run-on contributions to the
built upon areas of the site. The large on -site wooded ditch bordering the north side of the
property has a very flat long slope of approximately 0.24% and receives a small amount of
run-on from off -site sources.
Summary of Proposed Conditions
The work proposed generally includes installing a permanent stormwater collection and
treatment system for compliance with the NPDES permit condition for maintaining a
turbidity threshold of 50 NTU's in the runoff from the site. The stormwater collection
system is a series of pipes, channels and check dams that route a majority of the
developed site to an open sand filter. The sand filter is sized to capture the 1-year storm
and provide treatment for total suspended solids for 7.865 acres of the site's drainage
area. On -site developed areas are routed to the sand filter with the exception of a 0.476
acre area near Chappell Loop Road that drains overland to the road side ditch system
along Chappell Loop and Ploof Roads. The total disturbed area both on -site and off -site is
2.10 ac. The total area to be revegetated is 0.900 ac.
The open sand filter will also serve as a temporary sediment basin during installation of
the storm drainage system and will be converted over to the permanent sand filter function
once the upstream disturbed areas are stabilized. The temporary sediment basin will
utilize a perforated 8" PVC riser and gravel filter to remove sediment from the discharge
water.
II. Base Assumptions
Handling of Contributing Off -site Drainage Areas: There is a small off -site area of
0.112 ac. along a portion of the long north boundary that creates run-on into the existing

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wooded channel. A diversion ditch is proposed to route potential run-on below and away
from the sand filter.
Capture and Treatment of the 1.5 inches of Rainfall (Water Quality) event and the 1-
Year event: The open sand filter and two stone and gravel check dams capture the 1.5
inch rainfall design storm and the 1-year event and treat for suspended solids to achieve a
discharge turbidity of 50 NTU's. The 2-year event is captured almost in its entirety with
only a 1.42 CFS peak discharge from the sand filter basin. A 0.476 acre on -site gravel
area near Chappell Loop Road will bypass the sand filter, but will enter a series of grass
ditches that have had their drainage areas diminished significantly due to the new piping
and diverting of the existing overland flow to the sand filter basin. The existing grass
ditches along Ploof Road and Chappell Loop Road will have increased water treatment
capability due to the diverting of site generated runoff. The long flowpath of the on -site
area that bypasses the sand filter will receive significant reduction in turbidity when it joins
the remaining on -site generated flows at the proposed endwall at Ploof Road.
Pre -development versus Post -development Peak Flow from the Site: The hydrologic
condition will be improved in several ways that will reduce off -site peak flows in the post
development scenario. The amount of compacted gravel will be reduced by 0.61 acres
and converted to manage open space so there will be more infiltration in the new
managed open space areas and less runoff response. A large surface sand filter basin
and two rock check dams is designed to capture runoff from the site (with the exception of
the aforementioned 0.476 acres) during the 1.5-inch and 1-year storm. The 2-year event is,
largely attenuated and the 10-year. storm is attenuated by 13 CFS.
Since no impervious area is proposed, the hydrology is improved, and the sand filter basin
captures the majority of the site, no detailed predevelopment peak flow is calculated. See
the attached Storm Drainage Map for the pre -development flow patterns and the 10-year
peak flows from the two functioning pipe culverts that discharge to the Ploof Road ditch.
Hydrologic Soil Groups: The contributing areas are all Hydrologic soil group "A" with the
site being mapped predominately as fine sand with moderate to high infiltration rates (see
NRCS map below). Most of the. site draining tithe sand filter is developed and largely
gravel covered and appears to be in fill to an unknown degree.., Q�1�
Land Cover Types and Rational Coefficients: C5 "ys" e- •O� `l� S
•0L 40-1 JrL'i
Managed open space- (C=0.30) Vegetated areas. Good Hydrologic condition.
Compacted gravel area- (C=85) Onsite and offsite areas that are graveled.
Impervious areas- (C= 95)
Land Cover Types and CN's for Pre -development and Post -development Scenarios:
Three types of land cover are utilized for both pre -developed and post -developed
scenarios for on -site and off -site areas and appropriate curve numbers based on the
Hydrologic Soil Group "HSG" " are calculated in each sub -area as follows:

For HSG "A
Managed open space- (CN=36) Vegetated areas in the pre -development and post -
development scenarios. Good Hydrologic condition.
Compacted gravel area- (CN=80) Onsite and offsite areas that are graveled.
Impervious areas- (CN= 98)
Reference: "Hydrologic Analysis and Design", McCuen
Time of concentration for TR-20 Routing: Time of concentrations are taken to be 5
minutes due to the nature of the site.
Starting Tailwater Condition: For all pipe, exits begins at the crown of the pipe or at the
10-year high water elevation of the sand filter as applicable.
Rainfall Depth -Duration -Frequency as follows:
24-hour storm event
[1 yr] 4.00 in
[2 yr] 4.80 in
110 yr] 7.50 in
[100 yr] 13.00 in
Reference: Rainfall hyetographs from NOAA publication maps for coastal Brunswick
County.
Methodolo
Stormwater analyses conducted.with Hydrocad TR-20 computer model. Peak flows into
and out of sand filter are calculated by a TR-20 model. Smaller flows to individual
upstream measures are calculated with the rational formula. Erosion control peak flow
calculations (except for sizing the sediment basin) are based on the final ground cover as
this scenario creates a higher peak flow rate.
IV. Stormwater Calculations for Temporary and Permanent Measures
Silt Fence
1,850 linear feet of silt fence is proposed.
Silt Fence Outlet (Located at the southeast corner of site near Ploof Road
Contributing area = 0.615 acres (0.498 acre disturbed, 0.117 acre compacted gravel)
Rational 'c' = 0.498/0.615'0.40 + 0.117/0.615"0.85 = 0.486
Tc = 5 minute (assumed), 1-10 year= 7.50 in/hr
Q-10 year = 0.486 . 7.50 in/hr ` 0.615 ac. = 2.24 CFS
Required Volume behind overflow weir = 3,600 c.f. " 0.498 ac. = 1,793 c.f.
A 1,793 c.f. excavated pit will be provided in front of the outlet and calculated to the weir
elevation of 19.5'. Weir length= 5'.

b
Permanent Surface Sand Filter (Temporary Sediment Basin)
Contributing area when converted to permanent sand filter = 7.865 acres
Contributing area during construction = 0.809 acres
Disturbed area = 0.503 ac
Land cover areas during construction = 0.503 acre disturbed + 0.306 acre compacted
gravel yard.
Rational 'c' = 0.503/0.809*0.40 + 0.306/0.809*0.85 = 0.570
Tc = 5 min. (assumed), 1-10 year= 7.50 in/hr
0-10 year = 0.570 * 7.50 in/hr * 0.809 ac. = 3.46 CFS
Outlet riser will be provided with gravel filter to remove suspended sediments.
Volume required = 0.503 ac. x 3,600 c.f.= 1,811 c.f.
Volume provided = 7,116 c.f. at elev. 16.5'.
Surface area required = 0.01 x Q10yr = 0.01 x 3.46 CFS = 0.0346 ac. or 1,507 vs.
Surface area provided= 11,040 square feet at elevation 19.2'. (elevation of spillway)
Primary spillway= 4' wide weir in flow splitter box and 10' wide trapezoid grass and TRM
lined earth weir.
Permanent sand filter basin captures and treats the entire 1.5" and 1 year storm event for
total suspended solids.
Channel Calculations
Permanent Diversion to catch basin "H" (adjacent to berm flowing south)
Drainage Area (DA) = 0.33 ac. (all gravel), C= 0.85, Tc= 5 min., 1 10 year= 7.5 in/hr. Q 10-
year= 0.85*7.5in/hr*0.33 ac. = 2.10 CFS
Side slopes = 3:1 and 10:1, gravel lining, long slope = 1.0%, Channel depth = 6"
Flow depth 0.50', V-10 year= 1.46 ft/s.
Shear = T= yds = 62.4 * 0.50' * 0.01 = 0.312 Ib/sf. Gravel is stable.
Permanent Diversion bypassing offsite run-on from pond inlet channel
DA= 0.112 ac. (managed open space), C= 0.30, Tc= 5 min., 1 10 year= 7.5 in/hr.
Q 10 year= 0.30*7.5in/hr*0.112 ac.,= 0.25 CFS
Side slopes = 3:1, grass lining, long slope = 1.0%, Channel depth = 6"
Flow depth = 0.28', V-10 year= 1.11 ft/s.
Shear = T= yds = 62.4 * 0.28' * 0.01 = 0.17 Ib/sf. Grass is stable.
Permanent Diversion at Forebay top of slope (adjacent to berm flowing west)
DA= 0.353 ac. (0.302 gravel + 0.051 mos), C= 0.77, Tc= 5 min., 110 year= 7.5 in/hr.
Q 10 year= 0.77*7.5in/hr*0.353 ac.= 2.04 CFS
Gravel Section- side slopes = 3:1 and 10:1, long slope = 1.0%, Channel depth = 6"
Flow depth = 0.48', V-10 year= 1.42 ft/s.
Shear = T= yds = 62.4 * 0.48' * 0.01 = 0.300 Ib/sf. Gravel is stable.
Riprap section- 3:1, long slope = 13.0%, Channel depth = 6", d50= 6".
Flow depth = 0.43', V-10 year= 3.71 ft/s.
Shear = T= yds = 62.4 * 0.438' * 0.13 3.55 Ib/sf. Hand laid riprap w/ fabric is stable.
Permanent Diversion into Forebay
DA= 2.250 ac. (1.688 gravel + 0.103 impervious + 0.459 mos), C= 0.74, Tc= 5 min., 1 10
year= 7.5 in/hr.

Q 10 year= 0.74*7.5in/hr*2.25 ac.= 12.49 CFS
Grass Section- bottom width= 4', side slopes = 3:1, long slope = 1.0%, Channel depth =
12"
Flow depth = 0.68', V-10 year= 3.10 ft/s.
Shear = T= yds = 62.4 * 0.61' * 0.01 = 0.381 Ib/sf. Grass is stable.
Riprap section- 3:1, long slope = 9.0%, Channel depth = 12", d50= 9".
Flow depth = 0.47', V-10 year= 5.06 fUs.
Shear = T= yds = 62.4 * 0.47' * 0.09 = 2.64 Ib/sf. Hand laid riprap is stable.
Permanent Emergency Spillway Channel Out for Pond Forebay
Q 10 year= 17.13 CFS (TR-20 computer model calculated)
Grass Section- bottom width= 10', side slopes = 3:1, long slope = 1.5%, Channel depth =
12"
Flow depth = 0.46', V-10 year= 3.32 ft/s.
Shear = T= yds = 62.4 * 0.46' * 0.015 = 0.43 Ib/sf. Grass is stable.
Q 100 year= 54.8 CFS (TR-20 computer model calculated)
Flow depth = 0.89', V-10 year= 4.88 ft/s.
Shear = T= yds = 62.4 * 0.89' * 0.015 = 0.83 Ib/sf. Grass is stable.
Turf reinforcement matting rated at 2.0 Ib/sf is specified as a permanent liner w/ grass
cover.
Weir Calculations
Permanent Emergency Spillway Control Section Out for Pond Forebay
Q 10 year= 17.13 CFS (TR-20 computer model calculated)
Grass Section- bottom width= 10', side slopes = 3:1, long slope = 0.00%, weir depth =
2.0'.
Approach flow depth = 0.65', V-10 year= 2.40 fUs.
Q 100 year= 54.8 CFS (TR-20 computer model calculated)
Flow depth = 1.25' (flow elev. 20.45', top of dam elev. 21.50'), V-10 year= 3.25 ft/
Grass is stable. Turf reinforcement matting rated at 2.0 &sf-isspecified as a permanent
liner w/ grass cover.
Permanent Forebay Spillway Control Section Out for Pond Forebay into Sand Filter
Q 10 year= 32.0 CFS (TR-20 computer model calculated)
Riprap Section- bottom width= 12', side slopes = 3:1, long slope = 0.00%, weir depth =
12".
Approach flow depth = 0.78', V-10 year= 2.65 ft/s.
Riprap is stable. A continuous apron of riprap stone connects weir to sand bed to minimize
scour potential.
Permanent Weir in Flow Splitter Manhole Junction "I".
Q 10 year= 12.08 CFS (TR-20 computer model calculated)
Concrete Section- bottom width= 4', vertical side slopes, weir depth = 12".
Approach flow depth = 0.95'.
Permanent Rip -Rap and Gravel Check Dam Weir "A"
DA = 0.847 ac. (0.617 ac. gravel + 0.197 ac. mos + 0.033 ac. impervious), Rat C= 10.73, 1
10 yr= 7.50 in/hr
Q 10 year= 4.64 CFS

Riprap Section- bottom width= 5', side slopes = 3:1, weir depth = 12".
Approach flow depth = 0.40'.
A continuous riprap mat ties into the natural channel to prevent scour.
Permanent Rip -Rap and Gravel Check Dam Weir "B"
DA = 1.747 ac. (1.260 ac. gravel + 0.415 ac. mos + 0.072 ac. impervious), Rat C= 0.73, 1
10 yr= 7.50 in/hr
Q 10 year= 9.56 CFS
Riprap Section- bottom width= 7', side slopes = 3:1, weir depth = 12".
Approach flow depth = 0.53'.
A continuous riprap mat ties into the natural channel to prevent scour.
Culvert Calculations
30" RCP inflowing to CB-H
DA= 3.848 ac., (3.420 gravel + 0.428 impervious), C= 0.86, Tc= 5.0 min., 1 10 year= 7.50
in/hr
Q 10 year= C*I*A= 0.86 * 7.50 in/.hr * 3.848 ac. = 24.8 CFS.
Tailwater taken to be overflow elevation of weir 19.35'.
Computed HW = 20.72', HW/D=1.24 due to backwater effect of pond
Upstream CB-G rim elev.= 22.40'
24" RCP inflowing to CB-G
DA= 2.868 ac., (2.448 gravel + 0.420 imperv.), C= 0.87, Tc= 5.0 min., 110yr= 7.50 in/hr
Q 10 year = C*I*A= 0.87 * 7.50 in/.hr * 2.868 ac. = 18.71 cfs
Tailwater calculated at 20.72'.
Computed HW = 22.09', HW/D=1.82 due to backwater effect of pond
Upstream CB-F rim elev.= 23.70'
24" RCP Outflowing from Manhole Junction J
This pipe receives split flow from weir in manhole hole junction I.
10yr peak flow is 12.08 cfs (TR-20 computer model calculated) .
Tailwater assumed at crown of pipe at endwall at Ploof Road - elev. 14.50'
Computed HW = 15.79', HW/D=0.95.
RIP -RAP OUTLET PROTECTION
Riprap lined exit channel at 24" RCP at Endwall at Ploof Road
Q-10YR = 12.58 CFS, Vo-10YR = 4.01 CFS
PROVIDE 14 L.F. RIP -RAP LINING OF RECEIVING CHANNEL, d50 = 6", depth = 12",
filter fabric.