20061955 Ver 3_More Info Received_20080905

Z-/75v3
Dennis Ray Blackmon, R.L.S.
1023C W. Market Street
PO Box 1401
Smithfield, NC 27577
September 3, 2008
Cyndi Karoly
401 Oversight/Express Review Permitting Unit
2321 Crabtree Blvd.
Suite 250
Raleigh, N.C. 27604
Subject: Greystone Crossing Phase 3
Revised Plan
Pre-Construction Notification Application
Pleasant Grove Township, Johnston County
Telephone [phone]
Fax [phone]
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Dear Mrs. Karoly,
Please find five copies of the revised plan as per your letter dated August 26, 2008. The
revisions are as follows:
1. Please find attached the "Level Spreader Supplement Form" and the Items Check
List for the proposed level spreader. I submitted all the calculations and pictures
with the original submittal. If you can't find them please let me know.
2. Diffused Flow concerns:
a) A Preformed Scour Hole has been designed for the discharge points
between lots 166& 165 (ditch 49) and south of the club house lot (ditch
58). See attached calculations
b) The discharge point between lots 182&183 (ditch 53) flows into a wetland
not a riparian buffer, so I show a riprap dissipater pad to diffuse the Q 10
flow of only 1.62cfs.
c) The remaining discharge points between lots 56&57, lots 62&63, lots
187&188 return to an existing ditch well before they enter the buffer or
wetlands.
3. I have attached the calculations for this original scour hole as well. Information
was taken from actual survey data, not from the contour lines.
I noticed during my review that I had sized the Level Spreader #1 wrong. Please notice
the last sheet of calculations for the revised sizing.
1 of 2
If you have any questions or need any additional information, please give me a call at
919-934-3490.
Sincerely,
Z5:515? Andrew W. Hodge, P.E.
Cc Jamie Guerrero, PE Johnston County
2 of 2

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STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
LEVEL SPREADER, FILTER STRIP AND RESTORED RIPARIAN BUFFER SUPPLEMENT
This form must be completely filled out, printed and submitted.
DO NOT FORGET TO ATTACH THE REQUIRED ITEMS CHECKLIST AND ALL REQUIRED ITEMS (NEXT WORKSHEET)I
I. PROJECT INFORMATION
Project name GREYSTONE CROSSING PHASE 3
Contact name ANDREW HODGE
Phone number 934-3490
Date May 19, 2008
Drainage area number 1
II. DESIGN INFORMATION
For Level Spreaders Receiving Flow From a BMP
Type of BMP
Drawdown flow from the BMP cfs
For Level Spreaders Receiving Flow from the Drainage Area
Drainage area 78,844.00 ft2
Impervious surface area 11,827.00 fe
Percent impervious 15.00 %
Rational C coefficient 0.31
Peak flow from the 1 in/hr storm 0.56 cfs
Time of concentration 10.00 min
Rainfall intensity, 10-yr storm 6.21 in/hr
Peak flow from the 10-yr storm 3.48 cfs
Where Does the Level Spreader Discharge?
To a grassed bioretention cell? N (Y or N)
To a mulched bioretention cell? N (Y or N)
To a wetland? Y (Y or N) Please complete filter strip characterization below.
To a filter strip or riparian buffer? Y (Y or N) Please complete filter strip characterization below.
Other (specify)
Filter Strip or Riparian Buffer Characterization (if applicable)
Width of grass ft
Width of dense ground cover 35.00 ft
Width of wooded vegetation 25.00 ft
Total width 60.00 ft
Elevation at downslope base of level lip 253.83 fmsl
Elevation at top of bank of the receiving water 250.85 fmsl
Slope (from level lip to to top of bank) 4.97 % OK
Are any draws present? N (Y or N) OK
Level Spreader Design
Forebay surface area 23.80 sq ft OK
Feet of level lip needed per cfs 35 ft/cfs
Answer "Y" to one of the following:
Length based on the 1 in/hr storm? Y (Y or N)
Length based on the 10-yr storm? N (Y or N)
Length based on the BMP discharge rate? N (Y or N)
Design flow 0.56 cfs
Is a bypass device provided? Y (Y or N) OK
Form SW401-Level Spreader, Filter Strip, Restored Riparian Buffer-Rev.5 Parts I. and II. Design Summary, page 1 of 2
Length of the level lip
Are level spreaders in series?
Bypass Channel Design (if applicable)
Does the bypass discharge through a wetland?
Does the channel enter the stream at an angle?
Dimensions of the channel (see diagram below):
M
B
W
y
Peak velocity in the channel during the 10-yr storm
Channel lining material
29.00 ft Level spreader length OK.
N (Y or N)
Y (Y or N) Redesign channel to discharge to a dissipator pad adjacent to the wetland.
Y (Y or N)
3.00 it
3.00 ft
4.73 ft
0.29 ft
3.48 cfs
RIPRAP
• W •
------------
M
B
M
Form SW401-Level Spreader, Fitter Strip, Restored Riparian Buffer-Rev.5 Parts I. and It. Design Summary, page 2 of 2
DWQ Project
DIVISION OF WATER QUALITY - LEVEL SPREADER WORKSHEET (112007)
1. PROJECT INFORMgTION (please mplete the following information):
Project Name : V e 4 s „
Contact Person: Phone Number: 9'3 3 YF'Z3
Level Spreader ID:
Level Spreader Length 2 c/ ft. (perpendicular to flow)
Drainage Area ac. (on-site and off-site drainage to the level spreader)
Impervious Area tom. Z 7 ac. (on-site and off-site drainage to the level spreader)
Forebay Area Z 3. Y' owlt..5 f (0.2% of the contributing impervious surface area)
Maximum Filter Strip/Buffer Slope 40.'7-7 % (6% for forested, leaf littler cover, 8% for thick ground cover
grass
Max. Discharge from 1"/Hr Storm - s cfs
Max. Discharge to Level Spreader C3. J- Co cfs
Filter Strip/ Zone 2 Buffer Vegetation ? F? -?5 + s `/ y`(#lick ground cover or grass; canopied forest with leaf litter
groundcover)
Pre-treatment or Bypass Method Used b V
II. REQUIRED ITEMS CHECKLIST
Initial in the space provided to indicate the following design requirements have been met and supporting documentation is attached. If a
requirement has not been met, attach an explanation of why. At a minimum, a complete stormwater management plan submittal includes
a worksheet for each BMP, design calculations, plans and specifications showing all BMPs and outlet structure details, a detailed
drainage plan and a fully executed operation and maintenance agreement. An incomplete submittal package will result in a request for
additional information and will substantially delay final review and approval of the project.
Applica s Initials
Project Site was visited prior to designing level spreader.
?y 14 Date of the Site visit. PLEASE ATTACH TIME-DATED DIGITAL PHOTO OF EXISTING BUFFER CONDITIONS.
Level spreader is at least 13 ft. per cfs for thick ground cover or grass or 65 ft per cfs in canopied forest with leaf
litter for 50-foot buffer; 50 ft per cfs for 100-foot buffer, or 40 ft. per cfs for 150-foot buffer.
,f/%W Pre-Formed Scour Holes are on flat slopes only.
/ -1W No structures are located in protected buffers (must meet no practical alternatives criteria).
Design Alternative (if any) and Bypass method used:
ftUtti Bypass conveyance method is specified and plan details and calculations are provided.
lel lyl' Alternative design option is specified and plan details and calculations are provided.
Discharge to level spreader and subsequent filter strip is hydraulically and spatially separate from the bypass
discharge.
No structures are located in protected buffers.
10';LlcF Plan details for the bypass and outlets are provided.
IV?? W The operation and maintenance agreement includes annual erosion and vegetation repair.
c?ef The operation and maintenance agreement signed and notarized by the responsible party is provided.
LEVEL SPREADER OPERATION AND MAINTENANCE AGREEMENT
For STREAM CROSSING
Maintenance activities shall be performed as follows:
1. Inspect level spreaders after every rainfall until vegetation is established, and make prompt repairs.
2. After the area has been stabilized, make inspections every six months. Remove accumulated sediment
and debris, and maintain vegetation in a healthy, vigorous condition. Verify that the level spreaders are
distributing flow evenly. If problems are noted, make appropriate modifications to ensure even flow
distribution. Any down gradient erosion must be repaired and/or replanted as necessary.
I acknowledge and agree by my signature below that I am responsible for the performance of the two
maintenance procedures listed above. 1 agree to notify DWQ of any problems with the system or prior to any
changes to the system or responsible party.
Print name: Mike Coates - Crossroads Development Cori
Title: Co-Owner
Address: 12400 NC 50 North. Willow SaringS NC 27592
Phone: [phone]
Signature:
Date: Q& - -?3- Zoo g
Note: The legally responsible party should not be a homeowners association unless more than 50% of the
lots have been sold and a resident of the subdivision has been named the president.
1, R I40L. S' I'l l r non , a Notary Public for the State of-Nog-m; OA,2buy
County of ?O?n an , do hereby certify that ?_)_0 hae) Co +es
personally appeared before me this day of J qn e and acknowledge the due
execution of the forgoing level spreader maintenance requirements. Witness my hand and official seal,
\`P SI IE L
NOTARY z
PUBLIC
SEAL
My commission expires
Page 1 of 1
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CHANNEL LININGS
DITCH 49
STREET NAME OUTFALL DITCH BETWEEN LOTS 165/166
FROM STATION
TEMPORARY CHANNEL LININGS
DA = 1.27 Drainage Area
C = 0.31 Runoff Coefficient
Q2; 1.8 Design Discharge [cfs]
n = 0.022 Manning Roughness Coefficient
s = 3.90% Longitudinal Channel Slope
M = 4 Horizontal Component of Side Slope
B = 3.00 Bottom Width of Channel [ft)
y A P R Zav Zreq REMARK

0.150 0.54 4.24 0.13 0.14 0.14 GOOD
VELOCITY IN CHANNEL 2.0 FPS
SHEAR STRESS 0.4 LB/SF
USE: GRASS
PERMANENT CHANNEL LININGS
Q10 = 2.44 Design Discharge [cfs)
n = 0.038 Manning Roughness Coefficient
s = 3.90% Longitudinal Channel Slope [ft/ft)
M = 4 Horizontal Component of Side Slope
B = 3.00 Bottom Width of Channel fft)
y A P R Zav Zreq REMARK

0.243 0.97 5.01 0.19 0.32 0.32 GOOD
VELOCITY IN CHANNEL 2.5 FPS
SHEAR STRESS 0.6 LB/SF
USE: STRAW WITH NET
5/29/2008
9:23 AM
CHANNEL LININGS
DITCH 58
STREET NAME OUTFALL DITCH FROM CULVERT 14
FROM STATION
TEMPORARY CHANNEL LININGS
DA = 2.75 Drainage Area
C = 0.31 Runoff Coefficient
Q2 = 3.9 Design Discharge [cfs]
n = 0.022 Manning Roughness Coefficient
S = 2.50% Longitudinal Channel Slope
M = 4 Horizontal Component of Side Slope
B = 3.00 Bottom Width of Channel [ft]
Y A P R Zav Zreq REMARK

0.263 1.06 5.17 0.21 0.37 0.37 GOOD
VELOCITY IN CHANNEL 3.7 FPS
SHEAR STRESS 0.4 LB/SF
USE: STRAW WITH NET
PERMANENT CHANNEL LININGS
Q10 = 5.29 Design Discharge [cfs]
n = 0.038 Manning Roughness Coeffiient
S = 2.50% Longitudinal Channel Slope [fVft]
M = 4 Horizontal Component of Side Slope
B = 3.00 Bottom Width of Channel [ft]
I Y I A I P T R Zav 7ren RGMGRIC
0.410 1.90 6.38 0.30 0.85 0.85 GOOD
VELOCITY IN CHANNEL 2.8 FPS
SHEAR STRESS 0.6 LB/SF
USE: STRAW WITH NET
6/13/2008
10:52 AM
CHANNEL LININGS
DITCH 53
STREET NAME OUTFALL DITCH BETWEEN LOTS 182/183
FROM STATION
TEMPORARY CHANNEL LININGS
DA = 0.84 Drainage Area
C = 0.31 Runoff Coefficient
Q2 = 1.2 Design Discharge [cis]
n = 0.022 Manning Roughness Coefficient
s = 3.90% Longitudinal Channel Slope
M = 4 Horizontal Component of Side Slope
B = 3.00 Bottom Width of Channel [ft]
y A P R Zav Zreq REMARK

0.118 0.41 3.98 0.10. 0.09 0.09 GOOD
VELOCITY IN CHANNEL 2.9 FPS
SHEAR STRESS 0.3 LB/SF
USE: STRAW WITH NET
PERMANENT CHANNEL LININGS
Q10 = 1.62 Design Discharge [cfs]
n = 0.038 Manning Roughness Coefficient
s = 3.90% Longitudinal Channel Slope [ft/ft]
M = 4 Horizontal Component of Side Slope
B = 3.00 Bottom Width of Channel [ft]
y A P R Zav Zreq REMARK

0.190 0.71 4.56 0.16 0.21 0.21 GOOD
VELOCITY IN CHANNEL 2.3 FPS
SHEAR STRESS 0.5 LB/SF
USE: STRAW WITH NET
5/29/2008
9:23 AM
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