WSCO_WAKE_NCDEQ Approval Request Exhibits_20220729

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Ralph KPe h),,PB
PTSLand Surveying, PLLC
Mmy7, 2018
| Ralph \LPendergr oh]r,NCPLS#L-252O certify that ' portion ofthe property aL91O1Falls ofNeuse
Road, Raleigh, N[,drainstotbesoutheast,acmasFa|lsmfNeuseRoad,ayperthecerbfiedsunxeybvPT3
Land Surveying, dated December 6,2O17.

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107 IF ayel:levilllle SlreO, Skjil:e 200
Raleigh, INC 17601
Office: 9'19.848.4399
F-ax: 9'19.848.4395
CngGu°mcninq 0 Conssuffintg
March 2, 2022
Wake County Planning Department
Attn: Keith Lankford
Wake County Office Building
336 Fayetteville St.
Raleigh, NC 27601
Re: Falls Ridge West Watershed Analysis
Dear Keith:
Please find the results of the Falls Ridge West Watershed Analysis performed by Pabst Design
Group, PA below in this memorandum.
Executive Summary: Pabst Design Group, PA (PDG) of Raleigh, North Carolina has been
contracted by Falls Ridge West, LLC (Client) to provide a watershed determination and
analysis for the subject property (site) to Wake County (County) for their review. PDG
determined that approximately 0.604-acres of the site is incorrectly mapped and does not
drain to the Falls Lake Water Supply Watershed. Instead, the drainage area conveys to Perry
Creek watershed (non -water supply) which is located in the Lower Neuse River Basin via a
City of Raleigh (CoR) owned and operated stormwater pipe conveyance system. Below is a
summary of PDG actions and analysis findings.
Purpose: PDG was retained by Client to perform a watershed analysis on a 2.93 acre parcel
located at 9101 Falls of Neuse Road in Raleigh, North Carolina. The purpose of this analysis
was to demonstrate that a 0.604 acre portion of the subject property naturally drains away
from the Falls Lake Water Supply Watershed based on existing topography and drainage
structures which indicate that it drains to the Perry Creek watershed (non -water supply). To
provide this determination, PDG utilized a combination of information from topographic
survey prepared by PTS Land Surveying (PTS), dated December 6, 2017 and current GIS data
for existing stormwater inlets and conveyance as shown on the attached watershed exhibits.
PTS was sub -contracted by PDG to perform the boundary and topographic survey and
topography was field verified.
Analysis Method: PDG used PTS's topographic survey to delineate the two primary
watersheds located on the property separated by an existing ridgeline as indicated on exhibit
EX-WS1. The drainage area to the discharge point was delineated by traveling perpendicular
to all topography lines upstream until the drainage area reached closure as also indicated on
exhibit EX-WS1. The portion of the property on the western side of the ridgeline drains

offsite into the Falls Lake Watershed, but the hatched area to the east of the ridgeline drains
to an existing 24" pipe. Current Raleigh GIS data for the stormwater conveyance system that
this inlet contributes to, indicates drainage to the southeast until the system outfalls to an
open channel as illustrated on exhibits EX-WS1, EX-WS2 and EX-WS3. This entire drainage
system lies within the Perry Creek watershed (non -water supply) and not the protected Falls
Lake water supply watershed. PDG determined the point at which the surface runoff enters
the storm pipe network draining to the Perry Creek watershed (non -water supply) to be the
existing 24" storm pipe inlet just north of Falls of Neuse Road within the right-of-way as
indicated on EX-WS1.
Results and Discussion: PDG determined two watersheds existed on the property, Falls
Lake and Perry Creek. The area draining to Perry Creek consisted of runoff from the subject
property, public right-of-way, and adjoining property and totaled 38,338 square feet or
0.880 acres. Specific to the property, 26,297 square feet or 0.604 of an acre, drains to
Perry Creek.
Conclusions and Recommendations: Based on PDG's watershed analysis, PDG determined
that approximately 0.604 acres of the subject property drains to Perry Creek and not into
the Falls Lake water supply watershed. As a result, PDG recommends that this portion of
the property be removed from all Wake County and North Carolina Department of
Environmental Quality (NCDEQ) maps designating the Falls Lake watershed.
Attachments: Refer to the attached Watershed Exhibits EX-WS1 through EX-WS3 for PDG's
delineation.
Sincerely,
PABST DESIGN GROUP, PA
P. Dan Pabst, PE
Principal
Enclosure

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