20071184 Ver 1_More Info Received_20070921

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RQDAK ENGINEERING FAl'`+CIMII_f~ ,'~~;; ;~=4°W
Septernher ? l , 2007
Mr. Chris M. Pieper
107 Symphony Ct
Cary°, North Carolina 275 18
Reference: 5tc7rmwater Management Rcvicw and Engineering Evaluation
Property at 105 Symphony Court
Cary, Wake County. North Carolina.
Rodak F~.ngineering Document No. 07040
Dear' Mr. Pieper;
In accordance with our proposal dated September 4, 2007, Rodak fngineering, P.C`. (Rodak Engineering)
is pleased to peesent the following report sununariznrg our investigation of the stornwater management
system installed nn the property located at S05 Symphony Court Drive. 'fhe purpose of the investigation
was to identify storrnwater rnanagenrent structures installed nn the subject property, validate their design
to 6andie runoff" from the property and surrounding drainage area(s), and investigate the purpose of their
installation with respect to replacement of arty drainage features that may have formerly existed orr and
conveyed runoff- from the property. The property is currently undeveloped and wooded, but is intended
for sale as a residential development, pending a jtrdgrnent on the possible existence of a stream on the.
property thrit would preclude development pursuant to Meuse River buffer prcrtecdan rubs.
Sttzrmwater Management System Evaluation
Rodak Engineering completed tite following tasks in the evaluation of existing stormwaler management
measures that control and divert nznofi' generated on antl off the site:
• Conducted a site walkover on September 6, 2007. `The walkover included visual inslx:etion of
installed engineered drainage structures on the property, including scorn drains, outlet structures,
a rip-rap lined sediment basin and overflow channel, existing stream beds and surface drainage
fcatu res;
• Gathered information related to the site and surrounding properties contributing runoff to the
storrn4vater management system, pertaining to layout(s), tapvgraphy, total built-upon and
irnpcrvious surface area(s), setbacks, buffers, and other pertinent information that was used to
design the starrmvatcr collection and cnnveyamce measures fix post-construction runoff. This
information Duos obtained front the Town. ofCary's Planning f)epartment;
~, .. ,

Stormwater Management Keview and Engineering Evaluation
Property at 145 Symph<~ny Caurt
Cary, North Carolina
September 24, ?007
Page 2 of ~{
• Obtained and rcvievved dcsi},m infonnatian and speci{ieatians far the engineered stormwatcr
management system {'ram the `fawn of Crary;
• Reviewed infin•matian provided by you artd obtained From the Tawtt of Crary Geographic
lnfijrmatiort System (G{S) and North Carolina Flood Mapping Program on site soils, (load plain
elevation artd location data, etc. indicative of historical. drainage and surface feahrres on the site
that .were replaced by the engineered stotmwater management system.
Recultg
Rased on observations made during our site visit, we conclude that the drainage structure installed on the
subject property was designed to timetion lately as a storntwater conveyance system. We base our
canclusian on evidence observed an-site during our visit, as well as our review of site plans attained from
thc'Town of Cary. 'This evidertee is discussed in the following sections.
2.1. Inlet Co!lectfon Struc.7ure and Drainage Dltclt Lirrirrg
1r4'c observed standard rip-rap lining on the floor of ttte dtairtage ditch from the culvert structure at the
inlet Ic>cation of the ditch to the dzsc;harge location into a naturai intemttttent stream led. Based on our
obsen~ation, the installation of the rip-rap finer appeeus to have been conducted to reduce erasion in the
ditch, as it was not a natural stream bed. Itip-rap is not acceptable liner material for either natural ar
restored stream beds, as it does not promote sediment distribution ar aquatic grcnvth. Rip-rap is used as a
standard design technique; for erasion control in stormwater drainage ditches. '[n addition to the rip-rap,
our review of site plans obtained front the Tovv'n of Cary reveals that the area immediately downstream of
the discharge culvert. beneath Symphony Caurt was designed as a sediment traptbasirt. Phis was
c:onhrmed with otn• observations a{'side slopes of approximately 3:1 and rip-rap fining on t}te banks of the
structure. This is further indication that the drainage ditch was designed as an outlet structure and
conveyance measure far the sediment basin, as required by North Carolina Starmwater Best Management
Practice (BMP) design guidelines.
~.2. Slte Plarrs
Site plans of the development arannd the sutlject property were obtained from the City of Cary Planning
()ftwe and reviewed by Kodak Engineering. The site plans depicted the stormwater f3MP structures
observed during the site visit, and include the concrete conveyance pipes, outlet culverts, and sediment
detention basin downstream of the culvert outlet stnrcture (see Exhibit I }. 13ased an our revicvv of the site
plans, we concluded that the drainage ditch was likely installed downstream of the detention basin to
Canvey overflow fram the stnucture into the existing natural stream bed dawngradicnt of the site. Plans of
the neighboring sites were readily reviewed as part a{' our assessment, and we did not observe a
Starmwater easement ut the plans reviewed.
.. ., ~<,.... i,. ,t'

5tannwater Management Review and Engineering Fvaluatian
property at [ OS Syrnphany Court
Cary, North Carolina
September 24, X007
page 3 of 4
2.3. Baslrr trr:rl ditch S/rape Corrfigraratinrr
A natural ar restated stream hod has certain characteristic features including a bench {ar shelf;}, a
rncandcring pathway (referred to as sinuasiry) acrd a stream bed. F3ased an our observations of the
drainaa~e ditch an the subject property. we did nai observe a natural or man-made bench within thebanks
of the ditch, War did we abserve any degree of natural or engineered sirrtrasity in the flaw pathway. The
ditch appeared to have been designed as a straight overflew pathway for the sediment basin, as welt trs act
as a drainage divide between the subject site and the rreighbaring property, 1.03 Symphony Court. In
addition, the rip-rsp lining observed on the Clear and walls of the ditch waulci trot tx representative of a
natural or engineered stream. bed. "1`he lack of a bench and sinuosity within the ditch and the rip-rap lining
are considered evidence that the ditch functiarrs safely as an engineered drainage feature and as part of the
sediment basin Blv1P.
2.4. Urlrer Stormwater Devices
A detailed site inspection of additional stormwater collectiarr and conveyance devices revealed that all
storm -drain inlet structures installed along Symplrany Court are routed through the startmvater $MP
device irrsta}led an the subject. property via a distribution box located across the street fratn the culvert
structure, The distribution box has inlet cannoctians Pram the roof drains of the residential structures an
the surrounding properties, as well as a grated inlet installed an the property at 104 Symphony Court to
catlect yard nuraff. There was no indication of any natural drainage pathways discharging into the
drainage structure ar at any point along the ditch. The final grading of neighharirrg properties appears to
direct surface fraw itrto the ditch; further evidence that the ditch was not installed as a natural drainage
feature.
3 Cuaclusians
Based an our observations made during oar site visit and our review of the site plans, roe conclude that
the stannwater callectian and conveyance lecture installed at 105 Symphony Gaunt was designed and
installed to ftrrrctian primarily as a starrrrwater conveyance structure far the surface runoff generated by
the surrounding properties. There were na observed inlets to the drainage stnicture ether than Chase
connected to the siar•m~vater management s}*stern. °fhe absen'ed drainage feature was ertgincered as a
BIv1P treatment device to collect runoff and pollutants tram surrartnding properties and Canvey the nmott'
into a natural stream bed located dawngradcnt of the subject site. We were net able to obtain evidence or
infarrnatiarr regarding the former drainage feature (sfiream) located in the vicinity of the subject property
that was tilled in as part of the site develaparent activities and as indicated or: a historical sail Wrap
pravidod by you. Based err our site abservatians, there is na indication that the stream was relocated ar
exists in an}' atlrcr faun an the subject property. We conclude that ttre draiaragc ditch is err engineered
structure and does not finrctian as a restored stream hc~l. hurthcrmare, there is rro irrdicatian that the
fanner stream was diverted to flaw into the ditch.
1'he canclusians and recommendations presented herein are based, in part, upon infarrnatian pravidod to
us by you, the City cxf Cary and on our site observations. We have net verified the completeness ar
accuracy of the information pravidod by crtlrers.

StorniH~ater Management Keview and Engineerinb Evaluation
Property at l OS Symphony Court
Cary, North Carolina
September 2l, 2007
Page 4 of ~
Our observations made during the site work and recommendat'rans presented in this report are based upon
conditions readily visible at the site during our time there, and on applicable industry standards relevant to
design of scorn»vater management stnrctures. Kodak Engineering's scope of services is limited to the
services outlined in onr proposal.
We appreciate: the opportunity to provide these inspection services to you. If you have any questians. or
require any additional. infcrrmatitrn, please call us at (919) 23a-~i5&0.
Sincerely,
KODAK ENCiINIa,ErK,~~+ING, P.C.
f ~y~ J 1/
Simoon Lohdell E.l. ~ »'G~~~'r~}>,'y~'~
StaFFEngineer ~`~'~~l't,~ tiiN~„i~'V.4 .+j,
/ y
Andrew h9. ltexiak,l'.E.
Senior Engineer
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SE~ninr Prier Revrew~
DL?NCKi.Er ~~. Dt.Jlv'FiAlvf, P.C.
Bryson D. Trexler, ,Ir., Ph.D., P_C. ~'
Senior Hydrogeolofist
Attachments t~:xhibit t
R:~.PKOJEC.°rS~tiChris PiepcrtiRepartslS~V Maaxignment f'vHlusiticxrD7UA0,~k~.;

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