20180049 Ver 1_More Info Received_20180226

Goss, Stephanie 1)1� mL{ I
From: Eric Black <[e-mail]>
Sent: Monday, February 26, 2018 3:51 PM
To: Goss, Stephanie
Cc: Adam Paukovich; Ben R. Latino, Jr.; Rajit Ramkumar
Subject: RE: [External] RE: City of Durham Eno River Outfall Phases I and II
Attachments: 2018.02.26 Danny Smith Resubmittal Letter.pdf
Stephanie:
Attached are the design engineer's responses to the ENO River Outfall 401 further clarification questions. Please let me
know if you have any further questions.
Thank you,
Eric Black
Eric Black [ Project Manager
SEPI Engineering & Construction
1025 Wade Avenue i Raleigh, NC 27605
Direct: 919.747.5842 1 seoien¢ineerinrs.com
Connect with us: Linkedln I Twitter I Facebook
Confidentiality Notice: This message is intended only for the designated recipient (s). It may contain confidential or proprietary information and maybe subject to the
attorney-client privilege or other confidentiality protections. If you are not a designated recipient, you may not review, copy or distribute this message. If you receive
this in error, please notify the sender by reply e-mail and delete this message. Thank you.
From: Goss, Stephanie [mailto:[e-mail]]
Sent: Monday, February 19, 2018 8:23 AM
To: Eric Black <[e-mail]>
Subject: RE: [External] RE: City of Durham Eno River Outfall Phases I and 11
Thank you Eric.
Stephanie Z. Goss
Environmental Senior Specialist
Division of Water Resources.
Raleigh Regional Office
380o Barrett Drive
Raleigh, NC 27609
919-791-4256
E-mail correspondence to and from this address may be subject to the
North Carolina Public Records Law and may be disclosed to third parties

From: Eric Black [mailto:[e-mail]
Sent: Monday, February 19, 2018 8:02 AM
To: Goss, Stephanie <[e-mail]>
Cc: Rajit Ramkumar<[e-mail]>; Adam Paukovich <[e-mail]>
Subject: [External] RE: City of Durham Eno River Outfall Phases I and II
Stephanie:
I received the your e-mail and have forwarded it on to the design engineers. I will forward the information as quickly as
the provided it to me.
Thank you,
Eric Black
Eric Black [ Project Manager
SEPI Engineering & Construction
1025 Wade Avenue I Raleigh, NC 27605
Direct: 919.747.5842 ( sepieneineerinR.com
Conned with us: Linkedin I Twitter I Facebook
Confidentiality Notice: This message is intended only for the designated recipient(s). It may contain confidential or proprietary information and maybe subject to the
attorney-client privilege or other confidentiality protections. If you are not a designated recipient, you may not review, copy or distribute this message. If you receive
this in error, please notify the sender by reply e-mail and delete this message. Thank you.
From: Goss, Stephanie [mailto:[e-mail]
Sent: Monday, February 19, 2018 7:50 AM
To: Eric Black <[e-mail]>
Subject: City of Durham Eno River Outfall Phases I and II
Eric,
Please see the more info. requested letter for the above mentioned project. The original was mailed out on Friday.
Please do not hesitate to call me if you have any questions.
http://edocs.deg.nc.gov/WaterResources/0/doc/632555/Pagel.aspx
Stephanie Z. Goss
Environmental Senior Specialist
Division of Water Resources
Raleigh Regional Office
3800 Barrett Drive
Raleigh, NC 27609
919-791-4256
E-mail correspondence to and from this address may be subject to the
North Carolina Public Records Iaw and may be disclosed to third parties

F L %4'N E R,5
Tebriiary 26,201'8 M&C 03079-0012(40)
i
Mr. Danny Smith, Supervisor.
NCDWR, 401 & Buffer Permitting Unit
1617 Mail Service Center
Raleigh, NC 27699-1617
i' RE: City of Durham
Eno River Outfall Phases I and II
401 and Riparian Buffer Permitting
Project ID No.: DWR #18-0049
bear Mr. Smith:
On behalf of the City of Durham, we are submitting the requested additional
information for the subject project (Project ID No. DWR #18-0049) for your
review and approval.
® Provide a more detailed analysis of why boring or direction drilling
would not be feasible or practically accomplished to avoid impacts to the
stream channel. Provide site specific reasons why each crossing cannot be
completed using boring or directional drilling.
i' Response: This project involves replacement of an existing sanitary sewer
j with a larger pipe. The grade and depth of bury of this existing; sewer
has already been set during its design and construction in 1.968. The
feasibility of trenchless installatian of the proposed sanitary server outfall
E,vatt�-ilaat each En
�a�iir;r� IV River crossing was investigated as part of the preliminary
V�
design phase. Trenchless installation techniques were deemed unfeasible
17 3 0 vtlI Y D, 'r _= due to the shallow burial depth (typically less than 3 feet) of the sanitary
sever proposed to cross the Eno River.
Rall Liger, N'c :x;60,
16
The proposed outfall will be tying into the existing Eno Lift Station,
replacing the previously undersized pipe penetration at a fixed elevation.
'9'19.2 .3 �809 I- This fixed elevation cannot be lowered as the penetration is oriented
Eur
1,9 ' .S 61-8,1'
w% ,u,'rn c k i ter g; c"sm d o are
� S:\3079\0012\40-Permit\45-DEM, DEH, DOT, etc\ Buffer\ 2018.02.26 Smith Resubmittal Letter.doc .
i

Mr. Danny Smith
February 26, 2018
Page 2
directly above the floor slab. LoNveH,na the penetration elevation will
require complete replacement of the existing, lift station.
The elevation restriction at the lift station reduces the depth of backfill
over the top of the proposed outfall pipe at each Eno River crossing. A
48 -inch diameter pipe will protrude above the riverbed, impacting the
river's cross-section and flow path. To avoid this protrusion and
maintain flow capacity in the outfall, the crossings were changed to three,
24 -inch diameter parallel pipelines. The reduced pipe diameters will
a How for pipe burial completely below'the riverbed; however, pipe is too
shallow for a trenchless installation as there is not enough soil between
the top of pipe and. riverbed to provide structural integrity and prevent,,
potential collapse of the pilot or bore hole. In addition, due to the
shallow nature of these pipe crossings, soil may be displaced upward into
the riverbed during a trenchless installation, thereby changing the
geometry of the river's cross-section at each crossing location.
Provide a detailed analysis or construction sequence of how you propose
to work in the dry. Provide documentation of what size pumps will.,be
used and if spare pumps will be available in case of an emergency.
Response: It is anticipated that the General Contractor will elect to utilize.
a temporary cofferdam system'/ such as Portadarn, to isolate a portion of
the stream crossingata time allowing the river to continue to flow
around the area of'construction. Standard details for working in the dry
at the stream and Eno River crossings are showrn.on the plans; including
temporary coffer dains and/or temporary pump around systems.
Ultimate selection of damming streams and rivers, as well as specific
pump sizes and redundancy, will be at the discretion of the General
Contractor as part of their means and methods to construct the proposed
design.
® Provide an explanation of and details showing how turbidity� curtains or
other sediment barriers will be installed where the open-cut/excavation
method will be utilized to cross, stream and wetland complexes, - I
Response: It is anticipated that the General Contractor will elect to utilize
a temporary 'cofferdam system, such as Portadarn, to isolate a portion of

Mr. Danny Smith
February 26, 2018
Page 2
the stream crossing at a time allowing the river to continue to flow
around the area of construction. Standard details for working in the dry,
at the stream and Eno River crossings are shown on the plans, including
temporary coffer dams and/or temporary pump around systems.
Temporary silt bag details are shown on the plans; however, sediment
barriers will be at the discretion of the General Contractor as part of their
means and methods to construct the proposed design.
At this stage, it is not anticipated that a site visit is necessary for this project;
however, if the NCDWR should require a visit for additional clarification, or if
any additional questions should come up, please contact me at [phone] or
by email at [e-mail].
Sincerely,
McKIM & CREED, Inc.
Adam Paukovich, PE
Project Manager
Enclosures
cc: Mr. Jim Harding, PE, City of Durham
Mr. Ben Latino, PE, McKim & Creed
Mr. Eric Black, SEPI
File, w/encl.