20231363 Ver 1_Diffuse Flow Documentation _Redhawk_20230930

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September 30, 2023

Re: Redhawk Buffer Request – Diffuse Flow Narratives Provided by Project Engineers:

The following engineering and design considerations will be implemented to ensure that the proposed
project will not generate concentrated stormwater flow through the buffer:

• All ponds utilize riprap aprons designed to dissipate flow and reduce velocity of any discharge.

• Two of the three ponds have outfalls that are specifically directed away from the Catawba
buffer. These dissipate through vegetated streamside areas to maintain hydrology to
intermittent streams. The intended result is to diffuse water away from the buffer for less
bank/buffer erosion.

• The third pond with an outfall that is unavoidable directed towards the Catawba buffer has been
designed so that the outfall is outside of the buffer. Velocity-reducing measures will be
implemented such that the remaining outfall through the buffer is completed at a non-erosive
velocity and will be allowed to dissipate through the entirety of the buffer. This pond also
reduces impacts of drainage through the buffer from a pre/post standpoint.

• The proposed minor impacts required for construction are all temporary. Revegetation with
native seed mix is currently expected.

• Ponds are sized to handle the 1 year / 24 hr storm and the initial 1” rainfall. The Lake serves as
detention for the larger storms.

• Nutrient removal should occur within the wet pond basin. The pond will have plantings
following the NCDEQ guidelines for wetponds.

Thank you for your consideration of these materials and please contact me if you have any questions,
[phone] or email at [e-mail].

Sincerely,

Daniel Kuefler, PWS Len Rindner, PWS
Environmental Scientist Principal