SW3191104_2020.02.14-TLE First Sub. Response Letter_2/14/2020

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Gr❑LJP
ENGINEERS SURVEYORS
February 14, 2020
Corey Anen RE:
512 N. Salisbury Street
1612 Mail Service Center
Raleigh, NC 27699-1612
Re: The Learning Experience
Response Letter to 1st Site Plan Submittal Comments
Mr. Anen,
Please find responses below:
CHARLOTTE, NC
Two Metropolitan Area Offices:
Denver, NC I Fort Mill, SC
COLUMBIA, SC
www.ces-group.net
The Learning Experience
Tax PID: 06156003
Project No.: 7292.0819CD
1. Please submit the original signed and notarized Operation and Maintenance Agreement. The
Responsible Party field should be completed with the name of the individual signing the agreement. The
LLC and title of the signing individual should be entered in the Title & Organization field [15A NCAC 02H
.1042(2)0)]
Response: Updated O&M agreement included with this submittal.
2. Please delineate all wetlands on the plan sheets or add a note that none exist [15A NCAC 02H
.1042(2)(g)(iii)].
Response: Noted that there are no known wetlands on the existing conditions and final grading plan
sheets.
3. According to the Structure Table on Sheet C5.0, the invert into structure DI-7 from CO-7A is lower than
the invert of the pipe leaving DI-7. Please revise this to ensure proper drainage.
Response: Inverts have been revised.
4. Please provide calculations showing that the outlet protection from the sand filter is sufficiently designed
to prevent erosion during the peak flow from the 10-year storm (General MDC 4).
Response: Riprap apron calculations have been included in this submittal.
5. Please show a permanent easement on the plans that includes the SCM and a maintenance access at
least 10 feet wide that extends to the nearest public right-of-way (General MDCs 8 & 9).
Response: SCM access and maintenance easement shown on final grading plan. We provided two access
points from future public right of way. One down the main drive and parking to the sand filter and one along
the northern property line to allow access around the base of the retaining wall to access the outfall.
6. Please provide a geotechnical investigation that shows that the bottom of the sand filter will be at least
one foot above the seasonal high-water table (Sand Filter MDC 1).
Response: Have included geotechnical investigation report with this submittal. The paragraph discussing
SHWT is on page 4.
7. Please specify on the plans that the sand meet shall meet ASTM C33 or the equivalent (Sand Filter
MDC 6).
Response: Note added to meet ASTM C33.
8. The sand chamber must be designed to provide enough storage above the sand bed to hold at least

Project Number 7292.0819CD
The Learning Experience 0
Page 2
50% of the design volume below the overflow weir. Please revise the detail to provide enough storage
volume.
Response: Chambers have been revised to include enough volume.
9. It is recommended, but not required by the MDC, to provide a gravel layer surrounding the underdrain
pipe to prevent clogging or migration of sand into the pipe.
Response: Gravel layer now shown on cross section with geotextile fabric around stone.
10. Please update the Supplement EZ form to reflect any changes to the design and to include the SHWT
elevation (Field 18).
Response: Updated Supplement EZ form included with submittal.
11. Provide pdfs of all revisions, 2 hardcopies of revised plan sheets, and 1 hardcopy of other documents.
Pdfs must be uploaded using the form at: https://edocs.deq.nc.gov/Forms/SW Project —Submittal
Response: Noted.
Sincerely,
Sean Coldren