19950153 Ver 5_Email_20170104

Burdette, Jennifer a
From: Wehner, Judy
Sent: Wednesday, January 04, 2017 4:44 PM
To: Burdette, Jennifer a
Subject: FW: December Inspection, Benson Quarry Diversion Channel, Comments on
December submittal
For your information and file.
From: Holley, John
Sent: Wednesday, January 04, 2017 4:25 PM
To: Wehner, Judy <[e-mail]>
Cc: Boyer, Janet <[e-mail]>
Subject: FW: December Inspection, Benson Quarry Diversion Channel, Comments on December submittal
As per my discussion with Janet earlier today, I offer the following comments to supplement the reports you have already
received from Thad, and the email exchange below:
(1) The channel design data and results appear consistent with the procedures typically used for such large
watersheds. I am comfortable with accepting the designer's results subject to satisfactory field performance. If
the matting or channel geometry/profile prove to be problematic with respect to stabilization in the field,
additional channel structure and/or alternate linings will be needed to ensure acceptable stabilization. The
tabulated velocities and shear stresses appear acceptable assuming the culvert was modelled in the design;
matting to reinforce ground cover to be planted should therefore be acceptable without riprap as desired by
DWR. However, this again is subject to satisfactory performance. Turbulence around culvert outlets can increase
erosion potential. I found it interesting that they did not provided the design details captured by the consultant
electronically. It should be appropriate to request a disc copy for the file.
(2) As reported by Thad, the rock dam has been successfully containing sediment and should be maintained until the
channel stabilization is in the final stage, and the sequence will need to be modified to accommodate dewatering
of the rock dam, final shaping of the channel to prevent head -cutting above the culvert inlet, and final
stabilization of the areas now inundated.
(3) Appropriately designed runoff conveyance measures are necessary to collect runoff from upland areas and
deliver the discharges to the main channel without continued erosion of the floodplain slopes. Slope drains or
flumes should be designed to accomplish this.
As indicated in Thad's reports, the correction of erosion issues and final stabilization must be completed before the flow
to the channel is diverted. If there are any questions, please advise.
John L. Holley, Jr., PE, CPESC
State Sediment Specialist
NC Dept. of Environmental Quality
Division of Energy, Mineral and Land Resources
Raleigh Central Office
1612 Mail Service Center, 512 N. Salisbury Street
Raleigh, NC 27699-1612
Phone: [phone], Fax: [phone]
From: Valentine, Thad
Sent: Wednesday, January 04, 2017 3:24 PM

To: Boyer, Janet <[e-mail]>, Holley, John <[e-mail]>
Subject: FW: December Inspection
From: Valentine, Thad
Sent: Wednesday, January 04, 2017 3:05 PM
To: 'Nuwan Wijesuriya' <[e-mail]>
Subject: RE: December Inspection
Nuwan
I made that statement when we were at the rock dam at the lowest point in the project. After walking the enter project I
believe the potential for addition sediment migration down to the rock dam is possible and lowering the dam might not
be a good idea at this time. I don't think there would be a problem with pumping down the water if it's done correctly,
but we would need to see a pump down sequence and it would need to be reviewed and approved by Janet.
From: Nuwan Wijesuriya [mailto:[e-mail]]
Sent: Wednesday, January 04, 2017 2:51 PM
To: Valentine, Thad <[e-mail]>
Cc: Chubby Horton <Charles.Horton@ martinmarietta.com>, Arlen Carpenter <[e-mail]>;
Brian North <brian.north@ martin marietta.com>, Buzz Crosby<[e-mail]>
Subject: FW: December Inspection
Thanks for sending the report Thad. I wanted to ask you a follow-up question if I may. When we met out in the field you
mentioned possibly removing the middle portion of the rock dam to allow for the water to drain and avoid ponding over
seeded areas but in the inspection report you did not mention that...?
From: Valentine, Thad [mailto:[e-mail]]
Sent: Wednesday, January 04, 2017 2:19 PM
To: Nuwan Wijesuriya <[e-mail]>
Subject: December Inspection
104111111FAINO/ell
Nuwan
Here is the inspection report for the walk through of the new channel area, the hard copy is in the mail.