20071986 Ver 3_More Info Received_20080731

Environmental Consultants, PA
Road • Raleigh, North Carolina 27614 • Phone: [phone] • Fax: [phone]
www.SandEC.com
July 31, 2008
S&EC Project # 11083.P1
To: N.C. Division of Water Quality
401 Oversight and Express Permits Unit
Attn: Cyndi Karoly c/o Mr. Ian McMillan
2321 Crabtree Boulevard, Suite 250
Raleigh, NC 27604-2260
From: Bob Zarzecki
Soil & Environmental Consultants, P.A.
11010 Raven Ridge Road
Raleigh, NC 27614
Re: Richland Ridge Road Extension - DWQ 07-1986 V 3
Wake Forest, NC
juts ?0(18
DENR • YyAi t hK c eiNW iY
WETLANDS AND STORMWATER BRAND{
On behalf of the owner, LaScala Associates, LLC, please find attached the additional information that you
requested in your April 29, 2008 letter and discussed during our meeting on June 3, 2008. Please contact
me at [phone] if you have any questions or require additional information to complete your review
of this application.
It appears that your proposed stream crossing is at 60°. Please reconfigure this crossing to be
between 75° and 105° or show or bridge this crossing. If this cannot be done, the buffer impacts
will require mitigation.
As discussed during our June 3`d meeting, the angle that the road crosses the stream is dictated by
the existing Richland Ridge Road alignment south of the site. However, the buffer impacts are
less than 1/3 acre and 150 feet and as such are considered an "allowable" use and do not require
mitigation if approved.
2. Please eliminate the stub road portion of West Holding Avenue that intersects with Richland
Ridge Road from you proposed plans.
Construction of West Holding will terminate at the proposed Richland Ridge Drive as shown on
the attached plans and agreed to during our June 3`d meeting.
3. Because the Town of Wake Forest has not attended the BMP Certification Class, the DWQ is no
longer their accepting stormwater approvals as meeting the stormwater requirements of the 401
Certification Program. Therefore:
a. For drainage area number 1, please show the entire drainage area on a plan sheet with
all existing and proposed impervious surfaces (both on and off-site). If the proposed
percent impervious on this drainage area exceeds 24 percent, then a BMP that meets the
requirements laid out in Item I (b) below will have to be provided.
Charlotte Office: Greensboro Office:
236 LePhillip Court, Suite C 3817-E Lawndale Drive
Concord, NC 28025 Greensboro, NC 27455
Phone: [phone] Phone: [phone]
Fax: [phone] Fax: [phone]
Richland Ridge Road Extension
Response to DWQ 07-1986
Please find attached the delineated post construction drainage area for both drainage are
No. 1 and 2. Drainage area No. 1 is less than 24% and a level spreader designed to the
DWQ stormwater manual is proposed. The engineer has completed supplemental forms
(see attached) and will forward copies of the signed O&M agreements and required items
checklist under separate cover.
b. For drainage area number 2, please provide a BMP that removes a minimum of 85
percent of TSS and 30 percent of TN. For this BMP, please provide a completed BMP
Supplement Form, with all required items. The BMP Supplement Forms are available at
the following website:
http: //h20. enr.state. nc. uslsulbmp2brms. htm.
Please find attached the delineated post construction drainage area for both drainage are
No. 1 and 2. Drainage area No. 2 was revised such that it is less than 24% and a level
spreader designed to the DWQ stormwater manual is proposed. The engineer has
completed supplemental forms (see attached) and will forward copies of the signed O&M
agreements and required items checklist under separate cover.
Also, it should be noted that the project is in the Richland Creek water supply watershed
and as such is under 24% as a whole and will be reviewed by the Town of Wake Forest to
ensure compliance with their water supply ordinance.
4. Please indicate all stream impacts including all fill slopes, dissipaters, and bank stabilization on
the site plan.
Please find attached full size site plans, storm plans, details, and impact area showing the
requested information. Proposed stream impacts have not changed from those requested
in the application. Any modifications to this plan once final construction drawings are
developed will be provided to you and any less or additional stream impact will be
depicted on the plans.
As stated previously, the project engineer will be forwarding you copies of the signed O&M agreements
and required items checklist. Other that these, we believe that this response along with the attached
information should provide you the required information to complete your review of the applicant's
application. Please contact me if you have any further questions or require additional information. We
appreciate Mr. Millan's assistance and patience in working with us through this process.
Sincerely,
OSoil & En ironmental onsultants, PA
Bob Zarzecki,
Environmental Specialist
Page 2 of 2
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NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
LEVEL SPREADER, FILTER STRIP AND RESTORED RIPARIAN BUFFER SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part III) must be printed, filled out and submitted along with all of the required information.
I. PROJECT INFORMATION
Project name The Registry at Bennett Park
Contact name Warren M. Sugg, PE
Phone number 919-858-1811
Date July 14, 2008
Drainage area number Drainage #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 282,054 ft
Impervious surface area 34,540 fe
Percent impervious 0.12
Rational C coefficient 0.43
Peak flow from the 1 in/hr storm 2.784279614 cfs
Time of concentration min
Rainfall intensity, 10-yr storm 7.22 in/hr
Peak flow from the 10-yr storm 20.10249882 cfs
Where Does the Level Spreader Discharge?
To a bioretention cell? (Y or N)
To a wetland? (Y or N)
To a filter strip or riparian buffer? Y (Y or N)
Other (specify)
Filter Strip or Riparian Buffer Characterization (if applicable)
Width of grass It
Width of dense ground cover 200 ft
Width of wooded vegetation ft
Total width 200 ft
Slope (from level lip to to top of bank) 4 %
Are any draws present? N (Y or N)
Level Spreader Design
Forebay surface area 66 sq ft
Feet of level lip needed per cfs 13 ftlcfs
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, 24-hr storm? (Y or N)
Length based on the BMP discharge rate? (Y or N)
Design flow 3.4 cfs
Is a bypass device provided? Y (Y or N)
Length of the level lip 45 ft
Are level spreaders in series? N (Y or N)
Please complete filter strip characterization below.
OK
OK
OK
Level spreader length OK.
Form SW401-Level Spreader, Filter Strip, Restored Riparian Buffer-Rev.3 Parts I. and II. Design Summary, page 1 of 2
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
W
y
Peak velocity in the channel during the 10-yr, 24-hr storm
Channel lining material
N (Y or N)
Y
12 tt
1.3 ft
4 cfs
Rip Rap
? W
i ?

M

1
M
Form SW401-Level Spreader, Filter Strip, Restored Riparian Buffer-Rev.3 Parts I. and II. Design Summary, page 2 of 2

Level Spreader #2

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MULKEY INC. 6750 TRYON ROAD CARY, NC 2751 1 PO BOX 33127 RALEIGH, NC 27636 PH: 919-651-1912 FAX: 919-B51-191B WWW.MULKEYINC.CDM
Method for Sizing Trapezoidal Channels

Project Name: Bennett
Operator: wms
Job Number: 2006280.00
Date: 1/22/2008
Channel: Bypass Channel for Level Spreader #1
Description: 10-yr Design
Design Parameters =_> Cited tables and figures are from "NC Erosion & Sediment Control Planning and Design Manual"
Peak Flow, Q = 21.13 CFS
Channel Lining = Ri p Rap
Max. Permissible Velocity, Vmax = 4.0 FPS (Table 8.05a)
VR = 2.18 for use in Figure 8.05c
Manning's Roughness Coefficient, n = 0.02 from Figure 8.05c, using Retardance Classification "C"
Longitudinal Slope of Channel, s = 0.040 FT/FT
Bottom Width, B = 4 FT
Horizontal Side Slopes, M = 3 FT
design channel depth, d = 1.5 FT
normal water depth, dn = 0.9 FT
Channel Physical Calculations =_>
Cross-Sectional Area, A =
Wetted Perimeter, P =
Hydraulic Radius, R =
Find Normal Depth =_>
Zreq =
Zav =
6.03 SF
9.69 FT
0.62 FT
1.418
4.395 OK
Change values of B, M, and d until Zreq - Zav
Calculate Velocity =_>
Calculated Velocity, V = 3.50 FPS
Check to make sure V is less than Vmax OK
Check Freeboard =_> Need at least 6" of freeboard
Freeboard, df = 7.20 in
OK
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NCDENR
0?'(110F W aA pG

STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
LEVEL SPREADER, FILTER STRIP AND RESTORED RIPARIAN BUFFER SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Part III) must be printed, filled out and submitted along with all of the required information.
1. PROJECT INFORMATION
Project name The Registry at Bennett Park
Contact name Warren M. Sugg, PE
Phone number 919-858-1811
Date July 14, 2008
Drainage area number Drainage #2
II. DESIGN INFORMATION
For Level Spreaders Receiving Flow From a BMP
Type of BMP
Drawdown flow from the BMP cis
For Level Spreaders Receiving Flow from the Drainage Area
Drainage area
Impervious surface area
Percent impervious
Rational C coefficient
Peak flow from the 1 in/hr storm
Time of concentration
Rainfall intensity, 10-yr storm
Peak flow from the 10-yr storm
Where Does the Level Spreader Discharge?
To a bioretention cell?
To a wetland?
To a filter strip or riparian buffer?
Other (specify)
112,254 ft
23,209 ft2
n91
U.4/
1.211188705 cfs
min
7.22 in/hr
8.744782452 cfs
(Y or N)
(Y or N)
Y (Y or N) Please complete filter strip characterization below.
Filter Strip or Riparian Buffer Characterization (if applicable)
Width of grass ft
Width of dense ground cover ft
Width of wooded vegetation 80 ft
Total width 80 ft
Slope (from level lip to to top of bank) 6 %
Are any draws present? N (Y or N)
Level Spreader Design
Forebay surface area 45 sq ft
Feet of level lip needed per cis 65 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, 24-hr storm? (Y or N)
Length based on the BMP discharge rate? (Y or N)
Design flow 1.2 cis
Is a bypass device provided? Y (Y or N)
Length of the level lip 79 ft
Are level spreaders in series? N (Y or N)
OK
OK
OK
Level spreader length OK.
Form SW401-Level Spreader, Filter Strip, Restored Riparian Buffer-Rev.3 Parts I. and II. Design Summary, page 1 of 2
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, 24-hr storm
Channel lining material
N (Y or N)
Y
J IL
1 ft
7 ft
1 ft
4 cfs
Rip Rap
t W t
M
+ B ?
M
Form SW401-Level Spreader, Filter Strip, Restored Riparian Buffer-Rev.3 Parts I. and II. Design Summary, page 2 of 2
KEY
Level Spreader #1

MULKEY INC. 6750 TRYON ROAD CARY, NC 2751 1 PC BOX 33127 RALEIGH, NC 27636 PH: 919-951-1912 FAX: [phone] WWW.MULKEYiNC.COM
Method for Sizina Traaezoidal Channels
Project Name: Bennett
Operator: wms
Job Number: 2006280.00
Date: 1/22/2008
Channel: Bypass Channel for Level Spreader #2
Description: 10-yr Design
Design Parameters =_> Cited tables and figures are from "NC Erosion & Sediment Control Planning and Design Manual"
Peak Flow, Q =
Channel Lining =
Max. Permissible Velocity, Vmax =
VR =
Manning's Roughness Coefficient, n =
Longitudinal Slope of Channel, s =
Bottom Width, B =
Horizontal Side Slopes, M =
design channel depth, d =
normal water depth, dn _
Channel Physical Calculations =_>
7.53 CFS
Rip Rap
4.0 FPS (Table 8.05a)
1.42 for use in Figure 8.05c
0.02 from Figure 8.05c, using Retardance Classification "C"
0.040 FT/FT
1.5 FT
3 FT
1.1 FT
0.6 FT
Cross-Sectional Area, A = 1.98 SF
Wetted Perimeter, P = 5.29 FT
Hydraulic Radius, R = 0.37 FT
Find Normal Depth =_>
Zreq = 0.505
Zav = 1.028 OK
Change values of B, M, and d until Zreq <= Zav
Calculate Velocity =_>
Calculated Velocity, V = 3.80 FPS
Check to make sure V is less than Vmax OK
Check Freeboard =_> Need at least 6" of freeboard
Freeboard, df = 6.00 in
OK
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