BF_CCB0052_2011.12.20

529 Main Street
North Wilkesboro, NC 28659
Blue Ridge Engineering PLLC [phone]
P-0205
December 20, 2011
Mr. Martin Fridy
MPG Mooresville, LLC
1151 E. Washington Street, Suite 202
Greenville, SC 29601
Ref: Storm Drain Piping and Sediment Basin
Port Village Business Park
Mooresville, NC
Purpose
The purpose of this report is to provide a limited evaluation of the existing 66" corrugated metal pipe
(CMP) and stormwater basin located at the site.
Site Construction Activities
Duke Power Company installed coal ash structural
fill at the site beginning from January 1997 to
October 3, 1997. A plan for this work was
approved by NCDEHNR, now NCDENR, on
April 10, 1996. Plans dated March 15, 1996
prepared by Carlton Burton, PE included a
temporary sediment basin located adjacent to
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Rolling Hills Road. An existing 66" CMP provided
drainage through the site. These plans were revised
on May 17, 1996. Revisions included abandonment of the existing 66" CMP and installation of a new 66"
CMP located approximately 150 north of the original alignment. This plan calls for
370LF of pipe
downstream of DI-3 and includes a note that states "Terminate Storm Drain Pipe Before Basin Until Site is
Established".
The Lowe's home improvement warehouse retail store with associated parking areas and drives was
constructed at the site in 1998. Plans prepared by Joseph Griffin, PE dated April 21, 1998 show
approximately 150LF of pipe existing below DI-3
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and proposed enlargement of the sediment basin.
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A note included on these plans states "Sediment
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Basin Outlet Structure & CMP Sized to Include
Emergency Spillway for 100 Yr. Storm". The
basin was designed as an erosion control
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sediment basin and is not a stormwater detention
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Page 2 of 3
December 20, 2011
Field Inspection
I visited the site on December 16, 2011. The sediment basin and storm drainage
system appears to have been installed as shown on the plans dated April 21, 1998. No
significant deviations were observed. The sediment basin appears to have a significant
amount of sediment stored.
The outlet structure filter stone is covered with sediment preventing the sediment
basin from draining as designed. There is very little flow through the orifices. During
a significant storm event stormwater rises above the rim and passes through the top
grate.
,. The trash rack is functioning property but has a significant amount of trash caught
that needs to be removed.
The 66" CMP appears to be in above average condition for its age of approximately
13 years. No significant deterioration was observed. The jointing inspected appeared
to be constructed properly and in good condition. The flow capacity of the pipe
appears to be more than adequate.
The interior of DI-3 appears to be properly grouted and in good condition. No
significant water infiltration was observed. DI-3 has vertical drop of approximately 7
feet between inverts. There was minimal scour damage observed at the existing invert.

Page 3 of 3
December 20, 2011
Summary of Findings
❖ The basin is an erosion control sediment basin. It is not a stormwater detention pond. The outlet
structure filter stone is covered with sediment. Trash has accumulated on the trash rack.
❖ The 66" CMP was installed approximately 13 years ago and appears to be in above average
condition for its age. No significant water infiltration was observed.
Recommendations
1. Determine whether the sediment basin should be removed, left in place, or modified to
accommodate future construction.
2. If the sediment basin is to be left in place for erosion control, it should be cleaned out and new
filter stone installed prior to future construction activities.
3. If water is allowed to infiltrate into a pipe or storm drain box, the potential for a "sinkhole" to
develop is increased. Implement a plan of routine inspections to monitor the condition of the
storm drainage system including an interior inspection of the boxes and large diameter pipe.
Closing
This report only addresses the items included and should not be considered an exhaustive inspection of the
entire property, including hidden or inaccessible items. Information and recommendations provided in this
report are intended to reduce, but not eliminate, uncertainty regarding issues associated with the storm drain
pipe and sediment basin inspected.
For the Firm,
Blue Ridge Engineering PLLC
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C. Neil Shepherd, PE, PLS
Principal