20200321 Ver 1_ Final comment REC_20200514

Strickland, Bev
From: Morgan, Katie <[e-mail]>
Sent: Thursday, May 14, 2020 11:26 AM
To: Johnson, Alan
Cc: [e-mail]
Subject: [External] RE: copart 20-0321
Attachments: Spring Underdrain.pdf
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Hey Alan,
I wanted to pass along the engineers response to your comments and the schematic for the spring underdrain.
"Due to the height of the fill section in this area, the suggested 2:1 slopes, even with the addition of slope stabilization,
have a greater potential for current erosion and future issues with regards to slope failures and maintenance. Due to
the properties of the onsite soil, the site has used 3:1 slopes in the fill sections, and 4:1 slopes in areas between the
storage yard and the proposed stormwater drainage ditch. The proposed retaining wall and flatter slopes have been
utilized as a way to minimize impacts to the stream, provide for long term maintenance, and allow for the greatest
usable area for the project. The linear distance from the stream origin is 133' +/-. Due to the meandering nature of the
stream, this linear distance results in an impact length of 150'. Currently a spring box and linear section of discharge
piping are proposed to provided a flow path for the stream. However, perforated pipe and gravel envelope (French
drain) can be utilized and installed along the stream path to be certain that the maximum amount of discharge enters
the piping and continues its flow downstream."
Have a Great Day!
Katie L. Morgan, PWS, EP
Senior Project Manager — Professional Wetland Scientist (#3100)
PARTNER ENGINEERING AND SCIENCE, INC.
New Orleans, LA
CA23-838-1845 1 0: 504-777-3956 1 D: 800-419-4923 ext. 3748
More Than Just Assessments. Solutions — For a complete list of services, click here[nam02.safelinks.protection.outlook.com
From: Morgan, Katie
Sent: Tuesday, May 12, 2020 12:17 PM
To: Johnson, Alan <[e-mail]>
Cc: [e-mail]
Subject: RE: copart 20-0321

Thanks Alan,
I will send these comments to our client and the engineer.
Have a Great Day!
Katie L. Morgan, PWS, EP
Senior Project Manager — Professional Wetland Scientist (#3100)
PARTNER ENGINEERING AND SCIENCE, INC.
New Orleans, LA
C:423-838-1845 1 0: 504-777-3956 1 D: 800-419-4923 ext. 3748
More Than Just Assessments. Solutions —For a complete list of services, click herejnam02.safelinks.protection.outlook.com1
From: Johnson, Alan <[e-mail]>
Sent: Tuesday, May 12, 2020 7:45 AM
To: Morgan, Katie <[e-mail]>
Cc: Jonathan. [e-mail]
Subject: copart 20-0321
1) The distance from the retaining wall to the stream origin is —133 ft . If the slope began
at stream origin and was 2:11 the impact could be reduced by 90 ft (approximately).
2) The distance from top of slope to the stream origin is —38 ft. I assume this is the
parking lot design. I am not sure what the purpose of the 38 ft distance. Typically we
are dealing with buildings, etc. and not a large piece of pave property for parking
equipment. I would think there is or should be more flexibility for the type of
modification requested.
3) Slopes are 3:1/4:1 2:1 slopes would cut impact in half. More attention would be
required for sed/eros. The slopes will packed. The use of erosion control matting. 2:1
slopes aren't atypical and could be "fanned" out as you move from the stream outfall.
4) From top of slope to top of retaining wall a height of 20 ft. A French drain should be
utilized under the stream segment that is being filled. It could dry out the remainder of
the channel. If so, that would be considered a loss of use and could require
mitigation. Monitoring will be a part of the approval for a couple of years to ensure the
stream functions
Thanks
Alan

Divi%ion of Wa[cr Rc%0UFCCS
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.

NO.57
6" PERFORATED
LINE PIPE AND
EXCAVATION WITH
NONWOVEN GEOTEXTILE
FABRIC CONTECH C-60NW
OR APPROVED EQUAL
SELECT FILL-J
12"
r MINIMUM
SPRING UNDERDRAIN
N.T.S.
EXISTING
GRADE