20150333 Ver 1_Emails_20150511

Johnson, Alan
From:Johnson, Alan
Sent:Monday, May 11, 2015 10:41 AM
To:'Blandford, Patrick'
Cc:Parker, Michael
Subject:RE: Zemosa
Once the stream enters the culvert, it will spread over the entire width of the culvert until it reaches the opposite end.
The purpose of the baffles is to keep the stream “together” during base flow conditions as well as accumulate sediment
and assist in re-establishing the streambed elevation. These baffles would be below the current stream elevation.

Are the culverts to be cast in place? Since the culvert is “buried” a foot below streambed, can soil/sand/rock medium be
placed in the culvert during construction?

Alan

From: Blandford, Patrick [mailto:[e-mail]]
Sent: Monday, May 11, 2015 10:06 AM
To: Johnson, Alan
Cc: Mularski, Eric
Subject: RE: Zemosa

Alan,

Thanks for taking the time to step out in the field with Eric the other day for the Zemosa Acres project. I have evaluated
your suggestion regarding baffles for the culverts but am concerned about their inclusion this late in the game. Baffling of
the culverts will affect hydraulic performance and may adversely affect proposed water surface elevations thereby
requiring larger culverts. However, we will notch the upstream and downstream sills for each base flow culvert to
encourage the concentration of base flow to a smaller conveyance area through the culvert. We propose to provide a 4
foot wide notch, four inches lower than the proposed sill height of 12 inches. These notches will promote the development
of a thalweg within the culvert in order to maintain a significant enough depth. The overall proposed design of this project
is an improvement to the aquatic connectivity on this reach during baseflow conditions, which is impaired currently by the
steep, bare, and disconnected culverts. We appreciate your suggestions and will consider them on future design where
warranted.

Let me know if you require anything else at this time and I am happy to answer any questions you might have.

Patrick Blandford,
PE
D 704.338.6746 M 704.277.3766

hdrinc.com/follow-us

From: Mularski, Eric
Sent: Thursday, April 30, 2015 8:15 AM
To: Blandford, Patrick
Subject: FW: Zemosa

See Alan’s note below.

From: Johnson, Alan [mailto:[e-mail]]
Sent: Thursday, April 30, 2015 8:13 AM
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To: Mularski, Eric
Subject: Zemosa

Per our site visit yesterday. Alternating Baffles are suggested to be installed in the culverts that will allow for a 4 ft
opening which maintains base flow through the culvert(s). Space approximately 6 ft apart through the culvert.

I await the confirmation from your engineer and “detail”

Thanks
Alan

Alan D Johnson – Senior Environmental Specialist
NC Dept. of Environment & Natural Resources (NCDENR)
Division of Water Resources - Water Quality Regional Operations
610 East Center Ave., Suite 301, Mooresville, NC 28115
Phone: [phone] Fax: [phone]

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 unless the content is exempt by statute or other regulation.

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