SW5240501_Response To Comments_20240925

CRUMPLER
Consulting Services, PLLC
DEMLR Post-Construction Stormwater Program
Brianna Holland
512 N. Salisbury Street, Office 625Y
Raleigh, NC 27604
Re: Stormwater Permit No. SW5240501
Gaston Concrete (Franklin)
Response to Comments
1. Per the provided USGS topographic map,there appears to be a surface water located
within the project area. Please ensure the following:
a. Clearly identify and delineate the top of banks of the stream in the main set of plans
(Section VI, 8h). (It is not clear on the plans if the top of bank was delineated but not
labeled, in which case a label identifying the top of banks would be all that is needed
to resolve this comment.)
The top of banks have been labeled.
b. Ensure the vegetated setback is measured horizontally from the top of bank of each
side of streams for all perennial and intermittent surface waters within and adjacent to
the site. (per 15A NCAC 02H .1042(2)(g)(iii)). 15A NCAC 02H .1017 (10), 15A
NCAC 02H.1003(4)(a), 15A NCAC 02H.1042(2)(g)(iii). (See above comment.)
The measurement for the setback has been added.
c. 15A NCAC 02B .0731 (e)(7) Proposed development projects shall demonstrate
compliance with the riparian buffer protection requirements set forth in 15A NCAC
02B .0259.
No development is occurring near the riparian buffers.
d. The surface area of this surface water is indicated in Section IV, 6 of the Application
and the Supplement-EZ Form (Cover Page, Line 4). Note that the surface area of the
surface water is the area between the top of the banks of the streams and normal pool
of impounded structures.
These forms and items have been updated.
e. The surface area of this surface water is excluded from the project area in Section IV,
7 of the Application and the Supplement-EZ Form (Cover Page, Line 2 & Drainage
Area Page, Entire Site Column, Line 5).
These forms and items have been updated.
f. The Percent BUA for the project area is recalculated in Section IV, 8 of the
Application and the Supplement-EZ Form (Drainage Area Page, Entire Site Column,
Line 18).
These forms and items have been updated.
2. Application, Section IV, 10, Supplement-EZ, Line 5-7: For Low Density,the Total
Drainage Area proposed is comprised only of an Onsite Drainage Area component,
which is the Total Project Area listed in Section IV.7. Since only the property owned by
the applicant can be used to calculate the maximum allowed BUA, no offsite drainage
area can be included. It is acceptable to account for the BUA as off-site BUA..
The application and supplement-EZ have been updated.
3. Since this project drains to the Tar River (a Nutrient Sensitive Watershed), please ensure
2308 Ridge Road I Raleigh, NC 27612 I p: 919-413-1704 I e:[e-mail]

CRUMPLER
Consulting Services, PLLC
that the project is also compliant with the Tar-Pamlico Nutrient Strategy Rules 15A
NCAC 02B .0731..
The site will require buydown based on the attached SNAP tool
4. Swales:
a. The O&M Agreement indicates that this project utilizes dispersed flow only,the
plans indicate that swales are temporary. However,the Supplement-EZ, Low Density
Page, Line 4-5 indicates 3:1 side slopes, with a maximum 10-year storm velocity of 2
fps. Please revise for consistency and remove the items on the Supplement-EZ if
permanent swales are not proposed, or indicate that permanent swales are proposed
on the plans and O&M Agreement..
The swales have been removed on Supplemental-EZ as they are temporary.
5. Please upload the sealed cover page of the O&M Agreement Form. A complete O&M
Agreement Form is required per Sections V&VI, 3 of the Application and 15A NCAC
02H .1042(2)(j).
Attached and uploaded.
6. Supplement-EZ:
a. Cover, Line 7: This does not correspond to the plans. Revise the plans or Supplement-
EZ for consistency.
These forms and items have been updated.
b. Cover, Line 9: Unless BUA is proposed in the setback that does not meet NCAC
02H.1003(4)(c-d), please revise to "N/A".
These forms and items have been updated.
7. Please provide the riprap sizing calculations that correspond to the class and size shown
on the plans in order to demonstrate that the outlet of the site is nonerosive during the 10-
year storm per 15A NCAC 02H .1003 (5).
The riprap sizing has been attached.
2308 Ridge Road I Raleigh, NC 27612 I p: 919-413-1704 I e:[e-mail]