20131200 Ver 5_More Info Requested_20170809

Burdette, Jennifer a
From: Lucas, Annette
Sent: Wednesday, August 09, 2017 11:39 AM
To: David Odom ([e-mail])
Cc: Higgins, Karen; Burdette, Jennifer a
Subject: Review of Tryon Horse Farm received in hard copy on August 7, 2017
Dear Dave:
Please respond to the following requests for more information within the next 30 calendar days. Do not hesitate to
contact me should you have questions.
1. Regarding the plan sheets, please:
a. Provide a complete, up-to-date set of plan sheets that stands alone without needing to reference
portions of previous submittals.
b. Organize the next submittal so that each drainage area is clearly delineated, labeled and consistently
cross-referenced to the calculations.
c. Display and label every discharge point and provide a clear depiction of both its drainage area and all the
land downslope to the receiving stream.
d. Provide plan views that match the details for every outlet protection device on the project.
2. Regarding the calculations booklet, please:
a. Number the pages and provide a table of contents.
b. Clearly match the discharge points and devices shown on the plans with the calculations of pre- and post -
development flows and velocities and routings (as applicable).
c. Include runoff from any fill slopes associated with the project needs in the velocity and flow rate
calculations.
d. Provide engineers calculations demonstrating that the flows from every discharge point will be non-
erosive to both the land surface and the receiving stream during the peak flow from the 10 -year storm
event. The allowable velocities on steeply sloped wooded areas downslope of discharge points and small
ephemeral channels upslope of streams with bee quite low.
e. Provide engineering calculations demonstrating for any discharge points where you are proposing to
increase flow rates that the structural stability of the receiving stream will not be compromised.
3. Regarding the wet pond that is proposed to handle the southern portion of the Salamander Hotel site, please:
a. Meet requests number 1 and 2 above.
b. Correct the error on the supplement form regarding the design storm depth.
4. Regarding the dry ponds that are proposed to handle the northern portion of the Salamander Hotel site and the
Stable House Inn, please:
a. Meet requests number 1 and 2 above.
b. Show proposed contour lines and the level spreader on the plan sheets.
c. Indicate where the temporary pool will be stored.
d. Provide specific plan details with elevations labeled for each device.
e. Provide engineering calculations demonstrating that the 12" barrels that are proposed for these ponds
will effectively match pre -development flow rates. I typically see much smaller orifices proposed for
hydraulic control on devices this size.
i

f. Provide a signed and notarized operation and maintenance agreement that addresses the specific issues
for these dry ponds.
5. Regarding the underground pipe storage devices that are proposed to handle the Covered Arena area, the Crystal
Lagoon, and Village East:
a. Meet requests number 1 and 2 above.
b. Show proposed contour lines on the plan sheets.
c. Consider providing a sump or other pre-treatment device to facilitate maintenance (note this is a
recommendation, not a requirement).
d. Provide specific plan details with elevations labeled for each device.
e. Provide engineering calculations demonstrating that the outlet structures that are proposed for these
devices will effectively match pre -development flow rates. I typically see much smaller orifices proposed
for hydraulic control on devices this size.
f. Provide a signed and notarized operation and maintenance agreement that addresses the specific issues
for these devices.
Sincerely,
Annette
Annette Lucas, PE
Stormwater Engineer
Division of Energy, Mineral and Land Resources
Department of Environmental Quality
919 807-6381 office
annette.lucasA_ncdeELgov
https://deg.nc.gov/sw-bmp-manual
512 N. Salisbury Street, Office 942-V, Raleigh, NC 27604
1612 Mail Service Center, Raleigh, NC 27699-1612
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