20211818 Ver 2_More Information Received_20220406

Strickland, Bev
From: Kris Bass <[e-mail]>
Sent: Wednesday, April 6, 2022 10:33 AM
To: Phillips, George L CIV USARMY CESAW (USA)
Cc: Cohn, Colleen M
Subject: [External] Re: Hsu Pond Spillway Repairs / Raleigh / Wake County / SAW-2016-01125
/ Request for Additional Information
Attachments: HSU Pond PCN Additional 04062022.docx
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Thank you for the prompt and detailed review. I am providing the attached document as a draft with additional
information. I will be happy to edit this or include additional based on your response.
Many of the impacts associated with this project are the result of a delineation surrounding a severely damaged pond. I
think a site visit would go a long way towards understanding the conditions at the time of the delineation, the conditions
now, and the benefits of what we are proposing.
Please let me know your thoughts. I am available by phone and for meetings of all types!
Kris
On Tue, Apr 5, 2022 at 4:03 PM Phillips, George L CIV USARMY CESAW (USA) <[e-mail]> wrote:
Mr. Bass,
I have reviewed the above referenced project and need the following comments/questions addressed to evaluate the
proposed activities.
1. The PCN states that "the design is the minimum required to provide needed improvements." The need for
improvements is not disputed; however, it is unclear if the project is avoiding and minimizing to the maximum
extent practicable per general condition 23 (a) and (b). Please provide additional information to support each
impact. For example, what is the justification for the expansion of the embankment slope? How will the
proposed open water impacts "improve the safety of the embankment?"
2. It appears that the proposed impacts for spillway repair will result in permanent stream impacts. Based on of
review of the plans the proposed activities consist of the permanent discharge of fill material within a stream
channel.
3. It does not appear that the proposed impacts for the spillway repair meet the intent of NWP 3. NWP is for repair
of previously authorized fill. Based on the information provided it appears the boulder step pool activity is a fill
that was not previously authorized.
4. Will the proposed activities raise the level of the ordinary pool for the pond?

Please submit the above information within 30 days of receipt of this Notification or we may consider your application
withdrawn and close the file. Please call or email ([e-mail]) me if you have any questions.
Please let me know if you have any questions or concerns.
Lyle Phillips
Regulatory Specialist
US Army Corps of Engineers
CE-SAW-RG-R
3331 Heritage Trade Drive, Suite 105
Wake Forest, North Carolina 27587
Phone: [phone], Ext. 25.
Fax: [phone]
Email: [e-mail]
We would appreciate your feedback on how we are performing our duties. Our automated Customer Service Survey is
located at https://regulatory.ops.usace.army.mil/customer-service-survey/ . Thank you for taking the time to visit this
site and complete the survey.
Kris Bass Engineering
p: 919.960.1552
e: [e-mail]
w: www.kbeng.org

L I
KRIS BASS
E N G I N E E R I N G
USACE and NCDEQ
Re: HSU Pond Spillway Repairs
SAW-2016-01125
Request for Additional Information
219 E Chatham St, Ste 200
Cary, NC 27511
Office: 919.960.1552
Please accept and review the following responses to requests for additional information on this project. I am
available for follow-up discussion or a site visit as needed.
1. The PCN states that "the design is the minimum required to provide needed improvements." The need
for improvements is not disputed; however, it is unclear if the project is avoiding and minimizing to
the maximum extent practicable per general condition 23 (a) and (b). Please provide additional
information to support each impact. For example, what is the justification for the expansion of the
embankment slope? How will the proposed open water impacts "improve the safety of the
embankment?"
The existing embankment, including the front and back slopes are in poor condition and are steeper than
engineering standards for stable slopes. The expansion of these slopes is required to create a stable slope
that can also be maintained properly in the future. This extension is also following a recommendation from
a geotechnical engineering report that can be provided. The southwest corner of the embankment is very
close to a public road and special attention is needed in this area to ensure stability in this area. Additional
with is being proposed and a new front slope that will require extending out into the existing footprint of the
pond. This additional width creates the need for open water impact.
List of impacts with justification comments:
Wetland Impacts
1) Dam repair — permanent — This impact is needed to extend the back slope of the embankment to
create a stable, maintainable slope.
2) Dam repair — temporary — This impact is related to stone that will be placed in the water as part of
the spillway rebuild.
Stream Impacts
The area downstream of the pond has two sections of stream delineated. The first section starts at the outlet
pipe of the existing pond. The second is a reach that flows from the pond over the emergency spillway and
connects at the bottom. Due to the riser damage, flow was regularly occurring in both these areas during the
time of the delineation. However, the proposed repairs to the pond will change this flow pattern, resulting in
impacts as described below.
1) S1 —Permanent impact to the reach starting at the original pond pipe outlet. The proposed pond will
abandon and seal this pipe outlet, eliminating flow to this reach. A section of the reach will be
backfilled to create a stable slope on the back side of the embankment.
Kris Bass Engineering, PLLC

2) S2 —Temporary impact to rebuild the destroyed spillway area. The proposed project will re -build
this area as a system of boulder step pools. This area will serve as the primary outlet for the pond
and will flow constantly after project completion. Although the fill material will be a permanent
change to the configuration, the stream length in this area will remain after the project.
Open Water Impacts
1) Open water impact is necessary to widen the embankment in one area to better protect a public road.
Buffer Impacts
1) Temporary buffer impacts are needed to provide an access to the construction site. This buffer area
is already clear of trees.
2) Permanent buffer impacts are needed to create the back slope of the embankment.
2. It appears that the proposed impacts for spillway repair will result in permanent stream impacts. Based
on of review of the plans the proposed activities consist of the permanent discharge of fill material
within a stream channel.
Permanent fill of a stream channel is proposed inside an existing, destroyed spillway area. In my opinion,
the area is not a connected, viable aquatic habitat at this time. The area will be stabilized and the stream
length will be restored after project completion. It is my opinion that the new configuration would be an
improvement to the stability and potential stream habitats and functionality of this reach. This may be
adjusted to a permanent impact if more appropriate based on this description.
3. It does not appear that the proposed impacts for the spillway repair meet the intent of NWP 3. NWP is
for repair of previously authorized fill. Based on the information provided it appears the boulder step
pool activity is a fill that was not previously authorized.
Based on what we know about this pond, it appears likely that it was constructed prior to the need for
approvals of this type. My opinion is that the primary impact would have been due to the construction of
the embankment, and the primary outlet pipe and receiving stream would have been the likely impact. The
spillway area was not built with fill material and would have been meant only for large storm events. As a
result, the concrete and other material added to this area would not have been fill into an original stream.
Over time, damage to the original outlet device created a condition where the primary pond outflow was
split between the design outlet and the spillway, leading to the eventual designation of both stream
reaches.
It was our hope to have this project approved with NWP 3 as an attempt to accelerate the repair and
recovery of this area. Please let me know if further discussion or if there are other NWPs that could allow
this work.
4. Will the proposed activities raise the level of the ordinary pool for the pond?
No. The final configuration will result in a lower permanent pool of the pond based on the historic level.
Kris Bass Engineering, PLLC