20081476 Ver 1_Modifications_20081030

WWK
WDICKSON
community infrastructure consultants
October 29, 2008
Ms. Crystal Amschler
US Army Corps of Engineers
Raleigh Regulatory Field Office
331 Heritage Trade Drive, Suite 105
Wake Forest, NC 27587
DO
OCT 3 0 2008
UENR. VVATER QUAD! t r
WETLANR AMD STORMWATER BRANCH
RE: Response to comments on PCNs for Culvert Improvements at Kaplan Drive (AID No. 2008-
02785) and Swift Drive (AID No. 2008-02783)
Dear Ms. Amschler:
Attached to this letter are updated PCN forms, narratives, and design plans for the proposed Kaplan
Drive and Swift Drive culvert improvements. The modifications are based on your emailed comments
on October 20, 2008 and our subsequent phone conversations. As requested the PCNs have been
changed to NWP 14 - Linear Transportation Projects. Other requested changes have been made as
follows:
Kaplan Drive - The culvert design has been modified from a weir type baffle to one box remaining
open to convey base flow and baffling the second box one foot to convey storm flow (per Regional
Condition 4.2). The open box is in-line with relocated channel. The PCN form and narrative have
been edited to more accurately describe the impacts and the improvements to hydraulic efficiency.
Other minor edits have been made to the PCN form and narrative to reflect comments from NCDWQ
401 Unit.
Swift Drive - The culvert design has been modified from a weir type baffle to one box remaining open
to convey base flow and baffling the second box one foot to convey storm flow (per Regional
Condition 4.2). The open box is in-line with the existing channel. Other minor edits have been made
to the PCN form and narrative to reflect comments from NCDWQ 401 Unit.
The 401 Certifications have already been issued for the proposed projects. Please contact me if you
have any questions regarding this PCN submittal ([e-mail]). Thank you for your
prompt attention to these important flood control projects.
Sincerely,
W.K. Dickson & Co., Inc.
G?
Daniel Ingram
Project Scientist
cc: Ian McMillan, NCDWQ ./ to(??s
Craig Deal, Project Manager tis'wl
Tom Murray, PE, Project Manager t ?l
File: 60319.00. RA
720 Corporate Center Drive
Raleigh, NC 27607
Tel. [phone]
Fax [phone]
vvww.?l<diclaon.com lransEx -tation e 1Nater Resources • Urban Development e Geomatics
0% - 14-7 1, L)
Office Use Only: Form Version March 05
USACE Action ID No. DWQ No. 01 ` 41 tv V2_
(If any particular item is not applicable to this project, please enter "Not Applicable" or "N/A".)
L Processing 0 U' Re a Z f f
1. Check all of the approval(s) requested for this project: ; 011113 Y
® Section 404 Permit ? Riparian or Watershed Buffer Rules
? Section 10 Permit ? Isolated Wetland Permit from DWQ
? 401 Water Quality Certification ? Express 401 Water Quality Certification
2. Nationwide, Regional or General Permit Number(s) Requested:
NWP 14
3. If this notification is solely a courtesy copy because written approval for the 401 Certification
is not required, check here: ?
4. If payment into the North Carolina Ecosystem Enhancement Program (NCEEP) is proposed
for mitigation of impacts, attach the acceptance letter from NCEEP, complete section VIII,
and check here: ?
5. If your project is located in any of North Carolina's twenty coastal counties (listed on page
4), and the project is within a North Carolina Division of Coastal Management Area of
Environmental Concern (see the top of page 2 for further details), check here: ? ` D?
II. Applicant Information ®j;4
Owner/Applicant Information
0 C, T 3 0 2008
Name: City of Raleigh OENR-WATERQUALITY
"
Mailing Address: Public Works Department WETIANOSAN 5`J°°NCM
222 West Hargett Street
Raleigh, NC 27602-0590
Attn: Carl Dawson, P.E.
Telephone Number: [phone] Fax Number: [phone]
E-mail Address: [e-mail]
2. Agent/Consultant Information (A signed and dated copy of the Agent Authorization letter
must be attached if the Agent has signatory authority for the owner/applicant.)
Name: Daniel Ingram
Company Affiliation: WK Dickson
Mailing Address: 720 Corporate Center Drive
Raleigh, NC 27607
Telephone Number: 919-782-0495 Fax Number: 919-782-9672
E-mail Address: [e-mail]
Updated 11/1/2005
Page 1 of 8
III. Project Information
Attach a vicinity map clearly showing the location of the property with respect to local
landmarks such as towns, rivers, and roads. Also provide a detailed site plan showing property
boundaries and development plans in relation to surrounding properties. Both the vicinity map
and site plan must include a scale and north arrow. The specific footprints of all buildings,
impervious surfaces, or other facilities must be included. If possible, the maps and plans should
include the appropriate USGS Topographic Quad Map and NRCS Soil Survey with the property
boundaries outlined. Plan drawings, or other maps may be included at the applicant's discretion,
so long as the property is clearly defined. For administrative and distribution purposes, the
USACE requires information to be submitted on sheets no larger than 11 by 17-inch format;
however, DWQ may accept paperwork of any size. DWQ prefers full-size construction
drawings rather than a sequential sheet version of the full-size plans. If full-size plans are
reduced to a small scale such that the final version is illegible, the applicant will be informed that
the project has been placed on hold until decipherable maps are provided.
1. Name ofproject: Swift Drive Culvert Improvements
2. T.I.P. Project Number or State Project Number (NCDOT Only):
3. Property Identification Number (Tax PIN): 783843600 (Godwin), 783842468 (Ward)
4. Location
County: Wake Nearest Town: Raleigh
Subdivision name (include phase/lot number):
Directions to site (include road numbers/names, landmarks, etc.): Take the Gorman Street exit
from 1-40 and proceed north at the light at the end of the ramp. Take a left onto Avent Ferry Road and
go approximately 2.0 miles west. Take a right onto Swift Drive and go approximately 0.5 miles.
5. Site coordinates (For linear projects, such as a road or utility line, attach a sheet that
separately lists the coordinates for each crossing of a distinct waterbody.)
Decimal Degrees (6 digits minimum): 35.76817 ON -78.70300 °W
6. Property size (acres): 0.72 (area of disturbance)
7. Name of nearest receiving body of water: Simmons Branch
8. River Basin: Neuse River Basin (03020201)
(Note - this must be one of North Carolina's seventeen designated major river basins. The
River Basin map is available at http://h2o.enr.state.nc.us/admin/mgp-I
9. Describe the existing conditions on the site and general land use in the vicinity of the project
at the time of this application: The attached project narrative describes existing conditions.
10. Describe the overall project in detail, including the type of equipment to be used: The City of
Raleigh will improve the culvert at Swift Drive by installing twin reinforced 11'x5.5' box culverts. Due
to bedrock and utility constraints the culverts will not be buried or baffled. Approximately 190 LF of
Updated 11/1/2005
Page 2 of 8
modular block retaining walls will be installed downstream of the culvert to replace an existing concrete
block retaining wall and provide bank protection near existing structures. Upstream of the Swift Drive
culvert the banks will be regraded above the OHWM and stabilized with live stakes and native
plantings. This work will tie into the Lail Court culvert improvements approximately 150 LF upstream of
Swift Drive. Equipment to be used will include typical earthmoving equipment and construction
equipment.
11. Explain the purpose of the proposed work: The project will improve channel capacity and reduce
flooding as well as minimizing loss of land to the landowner.
IV. Prior Project History
If jurisdictional determinations and/or permits have been requested and/or obtained for this
project (including all prior phases of the same subdivision) in the past, please explain. Include
the USACE Action ID Number, DWQ Project Number, application date, and date permits and
certifications were issued or withdrawn. Provide photocopies of previously issued permits,
certifications or other useful information. Describe previously approved wetland, stream and
buffer impacts, along with associated mitigation (where applicable). If this is a NCDOT project,
list and describe permits issued for prior segments of the same T.I.P. project, along with
construction schedules. No permits exist at this time for this project.
V. Future Project Plans
Are any future permit requests anticipated for this project? If so, describe the anticipated work,
and provide justification for the exclusion of this work from the current application.
None at this time.
VI. Proposed Impacts to Waters of the United States/Waters of the State
It is the applicant's (or agent's) responsibility to determine, delineate and map all impacts to
wetlands, open water, and stream channels associated with the project. Each impact must be
listed separately in the tables below (e.g., culvert installation should be listed separately from
riprap dissipater pads). Be sure to indicate if an impact is temporary. All proposed impacts,
permanent and temporary, must be listed, and must be labeled and clearly identifiable on an
accompanying site plan. All wetlands and waters, and all streams (intermittent and perennial)
should be shown on a delineation map, whether or not impacts are proposed to these systems.
Wetland and stream evaluation and delineation forms should be included as appropriate.
Photographs may be included at the applicant's discretion. If this proposed impact is strictly for
wetland or stream mitigation, list and describe the impact in Section VIII below. If additional
space is needed for listing or description, please attach a separate sheet.
1. Provide a written description of the proposed impacts: Placement of the new culvert will impact
12 linear feet of stream beyond the length of the existing culvert.
Updated 11/1/2005
Page 3 of 8
2. Individually list wetland impacts. Types of impacts include, but are not limited to
mechanized clearing, grading, fill, excavation, flooding, ditching/drainage, etc. For dams,
separately list impacts due to both structure and flooding.
Wetland Impact
Site Number
(indicate on map)
Type of Impact Type of Wetland
(e.g., forested, marsh,
herbaceous, bog, etc.) Located within
100-year
Floodplain
( es/no) Distance to
Nearest
Stream
(linear feet) Area of
Impact
(acres)

Total Wetland Impact (acres)
3. List the total acreage (estimated) of all existing wetlands on the property:
4. Individually list all intermittent and perennial stream impacts. Be sure to identify temporary
impacts. Stream impacts include, but are not limited to placement of fill or culverts, dam
construction, flooding, relocation, stabilization activities (e.g., cement walls, rip-rap, crib
walls, gabions, etc.), excavation, ditching/straightening, etc. If stream relocation is proposed,
plans and profiles showing the linear footprint for both the original and relocated streams
must be included. To calculate acreage, multiply length X width, then divide by 43,560.
Stream Impact
Perennial or Average Impact Area of
Number Stream Name Type of Impact Intermittent? Stream Width Length Impact
(indicate on ma) Before Impact (linear feet) (acres)
1 Simmons Branch Placement of Perennial 12 12 0
003
Culvert .
Total Stream Impact (by length and acreage) 12 0.003
5. Individually list all open water impacts (including lakes, ponds, estuaries, sounds, Atlantic
Ocean and any other water of the U.S.). Open water impacts include, but are not limited to
fill, excavation, dredging, flooding, drainage, bulkheads, etc.
Open Water Impact
Site Number
(indicate on ma) Name of Waterbody

(if applicable)
Type of Impact Type of Waterbody
(lake, pond, estuary, sound, bay,
ocean, etc.) Area of
Impact
(acres)

Total Open Water Impact (acres)
Updated 11/1/2005
Page 4 of 8
6. List the cumulative impact to all Waters of the U.S. resulting from the project:
Stream Impact (acres): 0.003
Wetland Impact (acres):
Open Water Impact (acres):
Total Impact to Waters of the U.S. (acres)
Total Stream Impact (linear feet): 12
7. Isolated Waters
Do any isolated waters exist on the property? ? Yes ® No
Describe all impacts to isolated waters, and include the type of water (wetland or stream) and
the size of the proposed impact (acres or linear feet). Please note that this section only
applies to waters that have specifically been determined to be isolated by the USACE.
8. Pond Creation
If construction of a pond is proposed, associated wetland and stream impacts should be
included above in the wetland and stream impact sections. Also, the proposed pond should
be described here and illustrated on any maps included with this application.
Pond to be created in (check all that apply): ? uplands ? stream ? wetlands
Describe the method of construction (e.g., dam/embankment, excavation, installation of
draw-down valve or spillway, etc.):
Proposed use or purpose of pond (e.g., livestock watering,
local stormwater requirement, etc.):
Current land use in the vicinity of the pond:
Size of watershed draining to pond: Expected pond surface area:
VII. Impact Justification (Avoidance and Minimization)
Specifically describe measures taken to avoid the proposed impacts. It may be useful to provide
information related to site constraints such as topography, building ordinances, accessibility, and
financial viability of the project. The applicant may attach drawings of alternative, lower-impact
site layouts, and explain why these design options were not feasible. Also discuss how impacts
were minimized once the desired site plan was developed. If applicable, discuss construction
techniques to be followed during construction to reduce impacts. All impacts to waters of the U.S.
have been avoided and minimized to the maximum extent practicable. The attached project narrative
describes avoidance and minimization in detail. All conditions of NWP 14 will be satisfied to further
minimize impacts
VIII. Mitigation
DWQ - In accordance with 15A NCAC 2H .0500, mitigation may be required by the NC
Division of Water Quality for projects involving greater than or equal to one acre of impacts to
freshwater wetlands or greater than or equal to 150 linear feet of total impacts to perennial
streams.
irrigation, aesthetic, trout pond,
Updated 11/1/2005
Page 5 of 8
USACE - In accordance with the Final Notice of Issuance and Modification of Nationwide
Permits, published in the Federal Register on January 15, 2002, mitigation will be required when
necessary to ensure that adverse effects to the aquatic environment are minimal. Factors
including size and type of proposed impact and function and relative value of the impacted
aquatic resource will be considered in determining acceptability of appropriate and practicable
mitigation as proposed. Examples of mitigation that may be appropriate and practicable include,
but are not limited to: reducing the size of the project; establishing and maintaining wetland
and/or upland vegetated buffers to protect open waters such as streams; and replacing losses of
aquatic resource functions and values by creating, restoring, enhancing, or preserving similar
functions and values, preferable in the same watershed.
If mitigation is required for this project, a copy of the mitigation plan must be attached in order
for USACE or DWQ to consider the application complete for processing. Any application
lacking a required mitigation plan or NCEEP concurrence shall be placed on hold as incomplete.
An applicant may also choose to review the current guidelines for stream restoration in DWQ's
Draft Technical Guide for Stream Work in North Carolina (see DWQ website for most current
version.).
1. Provide a brief description of the proposed mitigation plan. The description should provide
as much information as possible, including, but not limited to: site location (attach directions
and/or map, if offsite), affected stream and river basin, type and amount (acreage/linear feet)
of mitigation proposed (restoration, enhancement, creation, or preservation), a plan view,
preservation mechanism (e.g., deed restrictions, conservation easement, etc.), and a
description of the current site conditions and proposed method of construction. Please attach
a separate sheet if more space is needed.
No offsite mitigation is proposed for this project. The existing channel is highly modified and offers
little to no aquatic habitat value. The project will result in the permanent foss of 12 LF of Simmons
Branch. Additional bank stabilization is either above the OHWM or replaces existing hardened bank
structures. Mitigative measures include impact minimization use of native plantings for erosion control
where practicable, and strict erosion control measures.
2. Mitigation may also be made by payment into the North Carolina Ecosystem Enhancement
Program (NCEEP). Please note it is the applicant's responsibility to contact the NCEEP at
[phone] to determine availability, and written approval from the NCEEP indicating
that they are will to accept payment for the mitigation must be attached to this form. For
additional information regarding the application process for the NCEEP, check the NCEEP
website at http://www.nceep.ngt/pages/inlieureplace.htm. If use of the NCEEP is proposed,
please check the appropriate box on page five and provide the following information:
Amount of stream mitigation requested (linear feet):
Amount of buffer mitigation requested (square feet):
Amount of Riparian wetland mitigation requested (acres):
Amount of Non-riparian wetland mitigation requested (acres):
Amount of Coastal wetland mitigation requested (acres):
IX. Environmental Documentation (required by DWQ)
Updated 11/1/2005
Page 6 of 8
Does the project involve an expenditure of public (federal/state/local) funds or the use of
public (federal/state) land? Yes ® No ?
2. If yes, does the project require preparation of an environmental document pursuant to the
requirements of the National or North Carolina Environmental Policy Act (NEPA/SEPA)?
Note: If you are not sure whether a NEPA/SEPA document is required, call the SEPA
coordinator at [phone] to review current thresholds for environmental documentation.
Yes ? No
3. If yes, has the document review been finalized by the State Clearinghouse? If so, please
attach a copy of the NEPA or SEPA final approval letter. Yes ? No
X. Proposed Impacts on Riparian and Watershed Buffers (required by DWQ)
It is the applicant's (or agent's) responsibility to determine, delineate and map all impacts to
required state and local buffers associated with the project. The applicant must also provide
justification for these impacts in Section VII above. All proposed impacts must be listed herein,
and must be clearly identifiable on the accompanying site plan. All buffers must be shown on a
map, whether or not impacts are proposed to the buffers. Correspondence from the DWQ
Regional Office may be included as appropriate. Photographs may also be included at the
applicant's discretion.
1. Will the project impact protected riparian buffers identified within 15A NCAC 2B .0233
(Meuse), 15A NCAC 2B .0259 (Tar-Pamlico), 15A NCAC 02B .0243 (Catawba) 15A NCAC
2B .0250 (Randleman Rules and Water Supply Buffer Requirements), or other (please
identify V Yes ® No ?
2. If "yes", identify the square feet and acreage of impact to each zone of the riparian buffers.
If buffer mitigation is required calculate the required amount of mitigation by applying the
buffer multipliers.
Zone* Impact
(square feet) Multiplier Required
Mitigation
1 6,813 3 (2 for Catawba)
2 0 1.5
Total 6,813
* Zone 1 extends out 30 feet perpendicular from the top of the near bank of channel; Zone 2 extends an
additional 20 feet from the edge of Zone 1.
3. If buffer mitigation is required, please discuss what type of mitigation is proposed (i.e.,
Donation of Property, Riparian Buffer Restoration / Enhancement, or Payment into the
Riparian Buffer Restoration Fund). Please attach all appropriate information as identified
within 15A NCAC 28 .0242 or .0244, or .0260. No riparian buffer mitigation is proposed. The
Droiect will not result in an increase in impervious surface and the existinp, buffer is in residential lawn or
right-of-way land uses. Where practicable native plantings will be utilized for bank stability and all
disturbed soil will be stabilized with temporary and permanent seed mixes.
Updated 11/1/2005
Page 7 of 8
XI. Stormwater (required by DWQ)
Describe impervious acreage (existing and proposed) versus total acreage on the site. Discuss stormwater
controls proposed in order to protect surface waters and wetlands downstream from the property. If
percent impervious surface exceeds 20%, please provide calculations demonstrating total proposed
impervious level. The proposed project does not require stormwater planning per DWQ guidance.
XII. Sewage Disposal (required by DWQ)
Clearly detail the ultimate treatment methods and disposition (non-discharge or discharge) of
wastewater generated from the proposed project, or available capacity of the subject facility.
XIII. Violations (required by DWQ).
Is this site in violation of DWQ Wetland Rules (15A NCAC 2H.0500) or any Buffer Rules?
Yes ? No
Is this an after-the-fact permit application? Yes ? No
XIV. Cumulative Impacts (required by DWQ)
Will this project (based on past and reasonably anticipated future impacts) result in additional
development, which could impact nearby downstream water quality? Yes 0 No
If yes, please submit a qualitative or quantitative cumulative impact analysis in accordance with
the most recent North Carolina Division of Water Quality policy posted on our website at
http:%/h2o.enr.state.nc.us/ncwetlands. If no, please provide a short narrative description: The
project is maintenance upgrades of an existing culvert to reduce flooding. The surrounding watershed is
almost entirely developed and the project should have no impact on future land use.
XV. Other Circumstances (Optional):
It is the applicant's responsibility to submit the application sufficiently in advance of desired
construction dates to allow processing time for these permits. However, an applicant may
choose to list constraints associated with construction or sequencing that may impose limits on
work schedules (e.g., draw-down schedules for lakes, dates associated with Endangered and
Threatened Species, accessibility problems, or other issues outside of the applicant's control).
Applicant/Agen`t's Aignatui
(Agent's signature is valid only if an
Updated 11/1/2005

"'?j <r f ?d Date
;ation' ei tte?from the applicant is provided.)
Page 12 of 12
PRE-CONSTRUCTION NOTIFICATION
NATIONWIDE PERMIT 14
PROPOSED SWIFT DRIVE CULVERT IMPROVEMENTS
SIMMONS BRANCH DRAINAGE BASIN
WAKE COUNTY, NORTH CAROLINA
PROJECT NARRATIVE
Introduction
The Swift Drive culvert improvements are part of a watershed wide plan for Simmons Branch to
reduce roadway and structure flooding in a predominantly residential neighborhood in West
Raleigh. The Swift Drive roadway currently overtops during the 2-year 24-hour storm event
based on built out land use conditions. Residential flooding occurs at five houses within the
vicinity of Lail Court and Swift Drive based on survey elevations provide by the City of Raleigh.
The proposed culvert improvement is designed to convey the 10-year 24-hour storm based on
future land use conditions. The proposed culvert improvements described herein will
substantially reduce roadway flooding in the project area and reduce residential flooding. The
culvert improvements at Swift Drive are part of a series of improvements throughout the
Simmons Branch watershed to reduce roadway and residential flooding. Completion of this
project would affect areas under U.S. Army Corps of Engineers (USACE) jurisdiction, specifically
12 linear feet of stream for culvert replacement. These are unavoidable and required to provide
channel stability and hydraulic function.
Site Location and Description
Simmons Branch drains approximately 1.2 mil from Western Boulevard to south of Avent Ferry
Road (Figure 1). The stream discharges to Walnut Creek just south of Lake Johnson. While
commercial areas in the vicinity of Western Boulevard have developed in recent years, the
majority of land use along Swift Drive is residential. Rain events in 2001 caused significant
residential flooding in the watershed precipitating the "Simmons Branch Drainage Study",
completed in 2002. Recommended project locations from the 2002 study are intended to
provide a 10-year level of service at major roadway crossings assuming built out conditions in
the watershed. The latitude and longitude coordinates are 35.76817°N -78.70300°W.
The existing culvert crossing at Swift drive culvert consists of 85 linear feet of twin 60"
reinforced concrete pipe. The culverts are crossing Swift Drive at approximately a 45 degree
skew. The culvert currently overtops during the 2-year 24-hour storm event. The two
residences located on the corner of Octavia Street and Swift Drive flood during the 10-year 24-
hour storm event based on model results.
Channel bank erosion exists on the upstream end of the culvert approximately 150 LF to Lail
Court. Downstream of the culvert a concrete block retaining wall has been constructed by a
private property owner. The wall extends for approximately 240 feet along the left bank and
approximately 100 feet along the right bank. The block wall has several support bars to help
prevent it from falling. Bedrock is present along the stream bed and bank downstream of the
Proposed Culvert Improvements in the Simmon's Branch Drainage Basin Page 2
culvert. According to recent soil borings partially weathered rock exists between 4.5 feet and
11.5 feet below the surface in the vicinity of Swift Drive.
Catch basins are located directly on top of the existing culverts. Furthermore, a utility pole is
located between the twin culverts under Swift Drive and will most likely need to be
permanently relocated during construction.
Additional utility relocations will likely be required in this area for gas, telephone, and water.
Sanitary sewer relocations are not anticipated at this location.
The topography on the property consists of moderately sloping terrain. Simmons Branch flows
from west to east through the middle of the property. The property generally drains to the
south, away from Swift Drive, eventually draining into Walnut Creek. The site is located in the
Neuse River basin (HUC 03020201).
Project Description and Purpose
The purpose of the proposed project is to increase channel and culvert efficiency and capacity to
reduce roadway flooding and flood risk to existing structures. The Swift Drive and Octavia
Street intersection is an important neighborhood thoroughfare; maintaining emergency access
and resident's access is important. Five homes in the project area are subject to flooding as
well. The proposed project is part of a watershed level initiative to reduce flooding. Bank
stability improvements will also decrease erosion and improve water quality and aquatic habitat.
Based on the analysis of the existing conditions hydraulic model for Swift Drive, a 22' x 5.5' box
culvert opening will convey the 10-year 24-hour storm event. Twin 11' x 6.5' reinforced box
culverts are proposed. One box will be place in-line with the existing channel and remain open
to convey base flow. The box culverts will be buried to the extent practicable but shallow
bedrock may preclude burying the boxes one foot deep. The existing channel is a pool
controlled by a downstream bedrock outcrop. As such, failure to bury the culverts one foot will
not impede aquatic movement since the culvert will remain inundated. The second box will be
baffled one-foot to convey only storm flows. Velocities discharging from the culvert during the
10-year storm will be in excess of 12 feet per second; however the downstream channel bottom
is bedrock making erosion less of a concern. The gabion walls recommended to replace the
existing retaining wall will provide the necessary erosion protection for the channel banks and
minimize loss of land to the homeowner. Increasing the culvert size to decrease velocity is not
feasible in this location due to space constraints. The entire retaining wall along the right bank
downstream of Swift Drive will be replaced with a gabion wall. The retaining wall along the left
bank will be replaced by a gabion wall for approximately 100 feet before tieing into the existing
retaining wall downstream.
Minor utility adjustments will be required for gas, water and telephone. The overhead utility
pole that is located between the existing culverts will require permanent relocation.°
The catch basins on top of the existing culverts will be moved to either side of the proposed box
culvert, so the runoff from the road will be conveyed through a pipe into the side of the box
culvert.
Proposed Culvert Improvements in the Simmon's Branch Drainage Basin Page 3
Channel improvements between Lail Court and Swift Drive include widening of the channel
above the OHWM to lower the 10 year water surface elevation to the existing top of bank
elevation and to tie the channel banks into the wider culverts at Lail Court and Swift Drive. A
Floodplain bench will be graded on the right side of the stream at the approximate elevation of
the 2-year peak water surface elevation. Live stakes will be planted along either side of the
stream for stabilization purposes.
Equipment to be used will include typical earthmoving equipment and construction equipment.
Jurisdictional Waters/Wetlands of the U.S.
One perennial stream (Simmons Branch) is located in the central portion of the property. This
stream is a tributary to Walnut Creek. The channel is typically 11 feet wide. The channel is a
highly modified urban stream that offers little to no aquatic habitat. Existing impacts include
bank erosion, concrete block retaining walls, and lack of cover and pool habitat (Figure 2). No
wetlands are present in the project area.
Avoidance and Minimization
Storm water design requirements were obtained from the City of Raleigh stormwater design
manual entitled "City of Raleigh Stormwater Management Design Manual" dated January 2002
and City of Raleigh code Section 10-3053. Design standards include:
• Systems must pass the 10-year 24-hour storm
• Culverts for more than 25 acres must have at least 2 feet of freeboard for the 10-
year 24-hour storm and 6 inch of freeboard for the 100-year 24-hour storm
• Pipe slopes shall be no less than 0.5% and no greater than 12%
• Minimum cover outside R.O.W is 0.5 feet
• Side slopes for vegetated channels should be no more than 3 to 1
Since the culvert improvement will be a retrofit in a predominantly developed area, some of the
design standards may not be feasible or cost effective. At a minimum each culvert crossing was
designed to convey the 10-year 24-hour storm based on future land use conditions.
Due to stream location, access considerations, and footprint requirements, limited impacts to
streams are unavoidable. The proposed culvert is essentially the same length as the existing
culvert minimizing impacts from the upgrade of the new culvert. Because of this upgrade, the
stream will be impacted by the increased length in culvert. The roadway width and fill slopes
have been minimized while still fulfilling geometry and traffic considerations. The stream
disturbance width will be minimized and all conditions of NWP 14 will be complied with.
The final site plan is the most practicable configuration in that it allows a usable yield of land
area while carefully configuring and placing infrastructure, utility lines, and roads to minimize
stream impact. Upgrading the culvert will reduce stress on the upstream channel bank and
preserve several large-sized trees on the downstream end.
Proposed Culvert Improvements in the Simmon's Branch Drainage Basin Page 4
jurisdictional Impacts
The total area of jurisdictional waters of the U.S. to be impacted by the proposed culvert
upgrade project is 0.003 acres of stream fill. Specifically, 12 linear feet of channel will be
impacted by the increased culvert length.
The impact is required due to geometry constraints for the culvert upgrade accessing the Swift
Drive ROW and is located adjacent to the stream fill.
No CAMA areas of environmental concern (AEC) will be impacted by the proposed culvert
upgrade project.
Best Management Practices
Prior to the beginning of any construction activities, the applicant will implement Best
Management Practices (BMP's) to minimize erosion and migration of sediments into affected
waterways (streams and wetlands) during the construction phase. A detailed Erosion Control
Plan will be developed and submitted for review and permitting by the local jurisdiction. It will
include appropriate erosion and siltation control devices placed between the construction area
and any affected waterway. These devices may include the use of mulches, sediment basins, silt
fences, or other devices capable of preventing erosion and migration of sediments. Monitoring
of BMP's will take place in accordance with the requirements of the North Carolina NPDES
general permit for construction activity to assure that the erosion and sediment control devices
are installed properly and maintained in a functioning condition.
Compensatory Mitigation
Off-site compensatory mitigation for this project is not proposed. Mitigative measures include
impact minimization, native plantings for bank stabilization where practical and replacing
concrete block retaining wall with modular block retaining walls.
Riparian and Watershed Buffers
Impacts to the riparian buffer will be minimal with only the removal of some small trees along
the stream banks and in the vicinity of the culvert upgrade. The trees that are removed will be
replaced and the buffer replanted with appropriate native species. The culvert upgrade at Swift
Drive does not result in an increase in impervious surface. The proposed project is a
maintenance activity and will not impact any forested buffers. The existing buffers are either
maintained residential lawns or maintained right-of-way. No buffer mitigation is proposed.
Floodplain Encroachment
The proposed project will not encroach upon the 100-year Floodplain and is not in a flood
hazard area.
Proposed Culvert Improvements in the Simmon's Branch Drainage Basin
Threatened and Endangered Species
Table 1 below lists threatened and endangered species in Wake County
or suitable habitat was observed in the project area. The proposed
adversely affect any protected species.
Table 1. Threatened and endaneered species in oroiect area
Page 5
. No protected species
project is not likely to
Common Name Scientific Name Federal Status Record Status
Vertebrates
Red-cockaded woodpecker Picoides borealis Endangered Historic
Invertebrates
Dwarf wedgemussel Alasmidonta heterodon Endangered Current
Vascular Plants
Michaux's sumac Rhus michauxii Endangered Current
Cultural and Historical Resources
A database search of National Register of Historic Properties indicated no listed historic
properties in the project vicinity. Additionally, a site visit determined that no existing structures
will be impacted by the proposed project.
O
?' aqO w oo
H
W (? w?N?a?5a
rw?„
Paz°a?xFw as
W
U
O
w o ??
O
N O
clq
? z a
PLO
? p Z
Cld 4-1
?+ '?/, NOS •o
N-- I
5--. x c QI
C w
?? ? N
N
V
O
W Lill-
w
? U
r., LO o a
??a
n0 `oo
h O N
Q h K U N
S ? Z CO
t Q m Z
W R Rq U-M
co -M
Y T JC7 F H J? VI
co
9
2 a ?ao
?~L11t0i? a Q O a a
O Q? s w m Ny w'
Q ? ?U Q ??NLdC ? O ?rt,,,y
Q O? JN d N w-
p? 9-??NNd9I
V Fi eo
5 aL ?? o
a k' a
m?UO Q M W
?`o
OR?6 mdn?d ° N 3 0
cLZ P\???E?
LLJ a `mr,. u 0 O v
? a aia d m
d? mwomma Z mOm
ODU lO T? N N Z W d
m Q?' ?`m?°,«'mw r a' 10 a Q a E a ?Q•c O
?0 a
w a r
0
U

X N r? X 1 0 1 I I I
W
Q J
_
Z Q
F-
W
?
L7
W p p ? ?

(n O Z Z Z J

O ? U) CJ ? ~
? Of O_ O_
W W ? Q (n (n L? J ?
O W ? Q W ? Of Of I- ?

U

7

n

J

?

W

W

-

? <<
- J
O Zln

'U,?
v m m? ud a o m a ° c O
(n

.Ar.J ;Qama ¦uffw
HHawam Uva
a O4 A8 M3 O8ddV
- i-
L
I
I
?
2
I?
d
(eW
L III 10OIYY .? I??Yrl ll? ???04d A803NO3NO A8O38Vd38d L
``
**
/
L
**
rr
.RAI(1LL .L.1IL?S ? .--1
3+tl0 tl3lNG rigl0i Oie
.t-tj - .,.pn4ro4Nq 4?unwwoa IY41 LYN
NOSX0 Vd C"
?6/ a, Ao Zjarolld HJVNMG MOTS S.LI? aW:4AOHdW1
M
NOIld11U53O 31V0 'ON j
??
98PIRI3o r,??^Ov ud
13`? sx rms'amL
Os?4 3rv?sz4aa4 oNeor
valWaLm ,L2I3ArIfla 1JIMS 78 IIV I
11 h?
a ? A gA
kW : :8 !? s
j: ?$ 1 lei
piggy a III ?l
a
III I. Al
HE IM11 111i v AN
N A i o 14 d d
Yl? W i',`'{ Y?
J ?
a ?
Inn
sr 5
I two
?R
? laaHS SSS
SNI'IHolvw
gill'
\1
1 rl_ I
I '
0?5 RS
=a
o
DO
i
i
x ?
?C
1 e??
i ?I I
zl
1

j IIi
I
I I
ill
I , ! \

I I i I
i i I !
; ( I

I
' I
I I I
I! I
!
?
j

Z II I
Ili

i t i t I I\)
OL I ? i l
- i dCkW
I l I
i t I I I! i I
I j !il I ! ! I
I
i I
!!!
j ! 'III ! l i \
i
i
i !IiI
I

i

t I
'

.. -
I
?
'

!
i I
(..-.
I

(
I

I
J

\

I I ( I ' I

! Ili I
j j I l l l i I

' I I ' Iii ! I
i i I!
l i l i ( I i
l i i
l
I
s
s
R .W-
G,
O
al
.tea w
z
s ?a
P.
0
a
P.
R
s
R
0
? I ? ? ? X ? ? ? ? R I B n ? n R n .? n I ? n n n
Rd 99TEV YOOi?WOL
LL-q=IN3 LLNNLAq mww
Lms-LOa3d - O*um,= NOI3wb\aw\OO4\OOwo\vwwimo\uONP1MIA=X.'I

W
F

3 MSS
?
Aav
i
I
W
oP"a
dO. a

O

a
., a A
g
:! R .. p R ,"S n n

W
F
R U]
AN
O*d so

W C\t
*
KWd j i
?T.
VLS °
s
az
dOdd
a
0
W.
a
c
m v
yrn1i amd?
CSRI?
N N?
"o?_wm9m
U dNU
HI O
u ?ca'a
a
mwa?d
om=aa
a?Hya?
m m? t?
cyb?cy
yEUt?o aZi
`s ad3m
0 w a
2,c'?Ut w ? E c
°?'d5m !•0 ? ? m
?`mv,£mw ? o_ rn a
S
I
a? a
S l
2^
8 _
I
t d,SSHS SSS
SNIIHD,LVW
??OX Wp I 1 ^
I •n?r
q °? °1? iar

2I?gNiRAi Uva
O& A9(13AONddY
wu

A903NJ3HO
AS GMN d3Nd S'II?.L?Q $ `?
~
wq LL3lND mworm ott
o1m11- anlani1mH4 Allun-
D Ru 1VN
°
NOS?101a °' a`v`? "'?'

Mid ,,,
f-,%6 &O i3wO-da af)VM H([ WHOiS SiuHW:IAOHJ I

NOI.LdIH]S30
31V0
'ON r; .
Oppa;o AD Y ?A7
`?'??Oua V/H ?„? ?
Y:l 37y'M7rdOH ONaO?
VHW'B1C09 Tv ? ?
`?'u.7/1?RD .L?IMD 7ffl llV 1 ?,
T*
ZI
r
1
W
N
J
a
W
W
? j
? J
7 ?
F U
w ?
3
N
(n

W
J
Q
U
Cn
2?0 d
3 ?ryN
0O
1)
y
?ymym QaOO? m
°
y
Cab Wtm
°
)
5 U
o my'9_m
mmm
aTi viq,cc
u?pduo
Ha'n
m amid ?$
m3LmO`2
S EF- a$
O. H
V Uf
U mC
fJ
C
?n?mma '
EVt?o
)
o``Z'a?i3m
yg."a?v9 ? :e «!
c
muiy,NE
9'uU$ a c ? E c
$m O
?Nw.L. NW @ a' rn m
a
F;
k

C
Q
V)
O
Q
J

w
n n

_ I ?

J
3 W?

?

<
w
H

W
n
.
<P V)

U
J

A J

u ?
0
/
/ a
N

LLJ
J
Q
U
V)
nd Lt*OIE wx/99/01
us OVU13lu9nx/a MW$d
M SWL30 - 5SPUNMvo Ha3?vva\ew\ov?\aov0\vwoe?cov\uencL\?4 (^+d\n