20060202 Ver 4_Emails_20150410

Johnson, Alan
From:Johnson, Alan
Sent:Friday, April 10, 2015 3:41 PM
To:'Lapsley, Jonathan'
Subject:RE: Briar Creek Sewer
Thanks the comments. They got lost in my stack of emails. Most questions were answered. But clarification and
modification may be required.

1)Replacing the 6 ft RCP with an 8 X 6 box, essentially over widens the stream. See concept below. There are

three possibilities: a) utilize 2 smaller culverts, one for base flow and the other perched to carry storm flow or b)
place alternating baffles in the pipe as shown in the second concept.

2)Regarding the geo tech fabric. I prefer neither the geo tech, nor the rip rap. If the toe can be worked and

stabilize using well staked heavy coir fiber matting or large coir fiber logs that will deteriorate over time leaving
behind a good vegetative cover, that is the prefer.

If we can get #1 handled, we should be good to go.

Thanks
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Alan

From: Lapsley, Jonathan [mailto:[e-mail]]
Sent: Thursday, March 26, 2015 8:58 AM
To: Johnson, Alan
Cc: Schnier, Keller
Subject: RE: Briar Creek Sewer

Good Morning Alan –

I reviewed your comments with our design team and how we have dealt with these similar issues on the previous phases
of the Briar Creek Relief Sewer project. I put some thoughts in red below for your consideration. If this leaves any
questions or concerns please let me know – happy to come meet with you face to face to work through these if need be
so we are all comfortable with how this will proceed.

Thanks for your time – if you need anything else just let me know.

Jon

Jonathan S. Lapsley, P.E. | CDM Smith 301 South McDowell Street, Suite 512 Charlotte, NC 28204

P: [phone] | C: [phone] | F: [phone] [e-mail] | cdmsmith.com

From: Johnson, Alan [mailto:[e-mail]]
Sent: Friday, March 20, 2015 2:14 PM
To: Lapsley, Jonathan
Subject: Briar Creek Sewer

I am reviewing the 401 application for the project.

You show no impacts for the culvert. Is this a new culvert? If so, I would think this would be under a NW 3. How much
additional (new impact) is due to the culvert and the rip rap apron. What is the base flow stream width. We may need
more details for the culvert. There is an existing 72” CMP culvert in place that will be removed and replaced with an
8’x6’ box culvert. See Sheet C-48 for design details.

Are their temporary stream crossings (for vehicles?)? If so, those should be included on the application No, there will
not be any temporary stream crossings for vehicles/equipment for access/crossing purposed during construction. All
crossings will be specific for the pipe installation and immediately restored upon completion of pipe installation across
it.

It appears the sewer line to cross the stream is done open cut. How is this work proposed to be done “in the dry”? Do
you plan to pump around? Are coffer dams proposed? The means and methods of constructing across the creek are
somewhat left to the Contractor’s discretion. Section 02233 of the specifications spells out the methods that are
acceptable and requires the Contractor to submit detailed plans and methods how the propose to do the work “in the
dry”.

Apparently for ALL the stream (sewer line) crossing, the only permanent impact is the stabilization of the bank? The
proposed stabilization range from 25 ft to 50 ft. This appears excessive for an open cut. I would assume the stabilization
(and bank clearing) would be based on the cut to the stream bank to install the sewer line? The Environmental
Assessment allows for a disturbance width of up to 40 ft, and based on experience from previous phases on this same
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project (this was larger pipe in places), the entire 40 ft was needed to complete the construction. It may be that the
Contractor disturbs less than 40-feet but they would be allowed to disturb up to 40-feet to complete the construction.

The stabilization calls for geo tech fabric at the bank toe. If the coir matting is properly staked and the slope properly
“packed”. I am not sure the geo tech fabric is needed. Worst case the bank may give and the fabric is left to move down
stream. Rip rap toe maybe to more appropriate if there is concern. It was our understanding that rip rap was not the
preferred material to be used for bank restoration and stabilization but understand your concern. If you prefer we
modify the detail to remove the geotextile fabric and replace with rip-rap we can do that.

Finally, to clarify, no rip rap is proposed to go in the stream, except as an apron for the replacement culvert. This is
correct, unless you suggest rip rap to be placed at the toe of some or all creek crossings related to the comment above.
Otherwise the only place we are proposing rip-rap is at the apron on the culvert replacement.

Thanks
Alan Johnson

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
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