SW1191201_Responce to Comments_20200224

TIMMONS GROUP
ACHIEVED THh !GH OURS.
Project: NCNG Morganton Regional RRC Phase II Date: 02/12/2020
Case #: SW1191201
Contact: Frank Slinsky, PE
Phone: [phone]
Email: [e-mail]
Comments from NCDEQ review has been addressed below. Our responses are in
Construction Document Submittal First Submittal Comments— 12/18/2019
NCDEQ REVIEW COMMENTS
Jim Farkas (919-707-3646, Jim. FarkasOncdenr.gov)
Please provide some documentation showing that Rodney Newton can sign on behalf of
the applicant (Section III, 1a).
Response: Col Rodney Newton is the Construction and Facility Management Officer and
the only signing authority for all construction projects the North Carolina National Guard.
Documentation on his position is secured, however you may reach the Project Manager
for the North Carolina National Guard, Mr. Harold Litzenberger [phone] to obtain
further information.
2. Please provide the information of the local jurisdiction that will be issuing the building
permit (Section III, 4).
Response: The application has been updated with the local jurisdiction information. The
local jurisdiction that will be issuing the building permit is the NC State Construction Office
(SCO# 16-14394-02B). The project has been approved to bid and is currently in the
bidding process. Updated application is attached.
3. The river basin that this project is located in is just "Catawba" (Section IV, 3). Please
revise.
Response: The stormwater application has been revised to Catawba, the updated
application is attached.
4. The information provided in the table in Section IV, 10 does not match the information
provided in the Supplement-EZ Form. Please address the following:
a. The "Total Drainage Area" item should be the sum of the "On -site Drainage Area"
and the "Off -site Drainage Area" items.
Response: The table in section IV, 10 has been updated such that the Drainage Area is
only the area draining to the SCM (per our phone conversation on 2/10). The offsite

drainage area is now zero(0) and the total drainage area is equal to the On -Site drainage
area.
b. The Proposed Impervious Area" item should be equal to the "Total' item from the
"Impervious Surface Area" table.
Response: The proposed impervious area has been updated such that it is equal to the
"total" item from the Impervious Surface Area Table.
c. The "Existing BUA" item should be the amount of BUA within the drainage area pre -
construction. Existing BUA that is removed and replaced is not reported as new
BUA, but rather as existing BUA.
Response: All existing BUA within the updated drainage area will be removed. The
existing BUA has been updated accordingly.
d. The "% Impervious Area" item should be the "Total' impervious area divided by the
"Total Drainage Area", expressed as a percent.
Response: The % Impervious Area has been updated accordingly.
5. Please indicate how the off -site impervious area was determined (Section IV, 11).
Response: There is no longer offsite area as the drainage area information section IV,
10 has been revised.
6. Please provide hard copies of the Supplement-EZ Form and O&M Agreement Form with
original signatures and seals (Section V & Section VI, 3).
Response: The signed and sealed supplement-EZ form is attached. The signed and
sealed O&M Agreement form is pending.
7. Please provide original initials next to each included item Section VI). Items that are not
included can be marked with "N/A".
Response: Initials are provided in section IV as requested, updated forms are attached.
8. Please provide a hard copy of the Application with original signatures and seals (Section
VI, 1).
Response: The original signature and seal was provided in the first submittal package. A
copy is attached for reference.
9. Please show the property lines, with bearings and distances, on the plans (Section VI, 8i).
Response: The parcel is 543 acres, the property lines that come near the site are shown
on the drawings to the north of the site with bearings and distances. The deed is attached.

10. Please dimension the BUA on the plans (Section VI, 8j). The information provided in
Section IV, 10 and the Supplement-EZ Form should be able to be verified on the plan
sheets.
Response: The existing and proposed BUA are shown as hatched areas on the
stormwater management plans (sheets C4.7 and C4.8). Dimensions have been added on
existing and proposed BUA. A table has been added to sheet C4.8 with BUA information
for the SCM drainage area and the total project area. The BUA can be verified from the
table and hatching. Updated plans are attached.
11. Please delineate the wetlands on the plans or provide a note stating that no wetlands
exist. Provide documentation of the qualifications and identity of the individual who made
this determination (Section VI, 8m).
Response: No wetlands exist on -site, a note has been added to sheets C4.7 and C4.8
stating such. A memo is attached stating the absence of wetlands on site by Robin Perez,
NC Wetland Assessment Method NC, Licensed Soil Scientist.
12. Please provide riprap sizing calculations showing that the inlets and outlet of the wet pond
are stable during the 10-year storm event (General MDC 4).
Response: Riprap sizing calculations for the inlet into the wetpond are attached. The
pond outlets into the existing storm system at an existing structure, therefore there is no
outlet protection.
13. As designed, the forebay is too large (Wet Pond MDC 5a). The forebay volume needs to
be between 15-20% of the main pool volume. Please revise.
Response: The forebay design has been revised, it is now 16.6% of the main pool
volume. Updated design calculations and drawings are attached.
14. Please provide a planting plan for the proposed wet pond (Wet Pond M DC 11).
Response: A planting plan is provided as sheet C6.1, updated drawings are attached.
15. Please correct the following issues with the Supplement-EZ Form:
a. Cover Sheet:
Line 2 — The project area should match Section IV, 7 of the Application.
Response: The Project Area has been updated to match Section IV, 7 of the Application.
The project area has been updated to just the 34.4 acre construction limits as the parcel is
543 acres (per our phone conversation on 2/10). The updated Supplement-EZ Form is
attached.
b. Drainage Area Sheet:

i. Please fill out the "Entire Site" column.
ii. Line 13 — See comment 4c prior.
iii. Line 15 — Since there is a net increase in BUA from pre -construction to
post -construction, do not include this item.
iv. Line 16 — See comment 4d prior.
Response: The "Entire Site" column has been filled out for the 34.4 acre project area as
discussed during our phone conversation (2/10). Line 13 has been set to zero as all
existing BUA within the updated drainage area will be removed. Line 15 has been set to
zero as recommended. The percent BUA has been updated to reflect the impervious area
divided by the total drainage area (divided by the project area for the "Entire Site" column).
c. Wet Pond Sheet:
i. Line 3 — The SCM should be sized to treat all surfaces at build -out
(General MDC 1).
Response: The site (area within 35 acre construction limits) has 5.41
acres of existing impervious. We are proposing 16.07 acres of impervious
(including future buildout). The SCM will capture and treat 13.09 acres of
impervious. Therefore, the SCM is over treating impervious by 2.43 acres as
shown on the stormwater management plan (sheet C4.7 and C4.8). Updated
forms and plans area attached.
We are over treating by 2.5+ acres
ii. Line 12 — Since this is not privately owned land, this item should be
"N/A" and an explanation of why it is "N/A" should be put on Line 55.
Response: Line 12 has been revised to say "N/A" and an explanation of
why has been added to Line 55. Updated forms are attacfhed.
iii. Line 14 — The O&M Agreement should comply with General MDC 11.
Response: The O&M Plan complies with General MDC 11. The updated
design calculations, plans and forms are attached.
iv. Line 15 — The O&M Plan should comply with General MDC 12.
Response: The O&M Plan complies with General MDC 12. The updated
design calculations, plans and forms are attached.
v. Line 26 — Per the calculations, the surface area of the main pool is only
19,145 sf.
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Response: The surface area of the main pool is now 21,548 sf, the
updated design calculations, plans and forms are attached.
vi. Line 28 — Please calculate the average depth of the wet pond using
either Equation 2 or Equation 3 from Part C-3 of the Manual.
Response: Equation 2 was used to calculate the average depth of the wet
pond. Updated design calculations are attached.
vii. Line 34 — The cleanout depth of the forebay is the distance between the
permanent pool elevation and the top of the sediment storage elevation.
Response: The elevation of the permanent pool is 1201.5, the elevation
of the top of the sediment storage at the entrance of the forebay is 1197.0.
The cleanout depth has been updated to 54". Updated drawings and forms are
attached.
viii. Lines 43 and/or 44 — Wet Pond MDC 5b requires that the forebay
entrance be deeper than the forebay exit.
Response: The forebay has been updated such that the entrance is
deeper than the exist, refer to sheet C8.14. Updated drawings and forms are
attached.
16. 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:Hedocs.deg.nc.gov/Forms/SW Project Submittal
Response: Revised calculations, revised forms and two copies of the revised plans are
attached. A pdf of all revisions has been uploaded to the above web address.
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