20231127_ADI_Received

3M Industrial Minerals Product Division
4191 Hwy 87 South
Moncure, NC 27559
11/20/2023
Mr.Adam Parr, PE
NC Department of Environmental Quality RECEIVED
Division of Energy, Minerals,and Land Resources
512 North Salisbury Street, 51b Floor NOV 2 7 2923
Raleigh, NC 27604
LAND QUALITY
Re: 3M Pittsboro Mine, Mining Permit No. 19-16 MINING PROGRAM
Dear Mr. Parr:
3M Company(3M)is pleased to submit this response to nine comments in the letter sent to
Andrew Miller on September 20',2023; regarding 3M's mine permit modification/application.
Please see the individual responses to the comments below, along with the included drawings.
Comment#1:
Please verify that the overburden waste pile has been engineered to avoid slope stability issues.
3M Response:The overburden waste pile has been engineered with 2:1 maximum slope and
terraced with 30'wide benches every 50'vertically.The current plan has been stamped by a
professional engineer,submitted, and approved by NC DEQ in 2017. No changes to that plan
have been made since the last approval.
Comment#2:
It is difficult to see affected area boundaries and boundaries of excavations,plant area,
overburden area etc. Please submit a map with increased line weight or hatching to clearly
identify these areas. Please consider also submitting a version without the imagery base layer.
3M Response:See attached drawing PBOR-888-C-716A
Comment#3:
Details on the proposed changes to Outfall3 and 4 and the symbology/hatching for their
features are difficult to discern.
3M Response: See attached enlarged plan showing these changes for Outfall 3 and 4. 3M is not
including any other enlarged details for BMPs since there is nothing else that has changed at the
site.These details were provided to the agency in past submittals. Please let us know if you have
any questions on specific locations and we are pleased discuss further.
Comment#4:
The plan submitted shows outdated references including "Ponds to be built in 2019". Please
provide updated erosion and sediment control plan sheets that reflect the current site conditions
including any updated plan details, sediment basins, haul roads, diversion ditches, outfalls, as

well as other erosion and sediment control features. The existing E&SC plan last revised 2017
and updated 2021 should be updated to include the proposed stormwater changes.
3M Response:See updated drawing PBOR-888-C-716, revision 9.
Comment#5:
Please clearly identify and label on the mine map the latitude and longitude of permit boundary
corners so field verification of permit boundaries can be conducted during future inspections.
3M Response:See updated drawing PBOR-888-C-716, revision 9.
Comment#6:
Please provide clarification regarding the "Forestry Activities"and limits thereof that are to
continue in unmined areas. Please clearly identify and label the Forestry Activity boundaries. Be
advised that removal of significant numbers of the existing trees may necessitate additional
screening measures in some locations.
3M Response: "Forestry activities"generally relate to parts of the 3M site within the permit
boundary which are not planned to be used for relative near-term mining operations.3M
contracts with a 3 d party forester and these areas of the site on an annual basis for forestry
services.Over the last several years this forestry contractor has been Gelbert, Fullbright, &
Randolph Forestry Consultants(GHR).The forestry services that are conducted may be (but not
limited to)tree surveys, managing timber sales,tree clearing,tree planting and weed
abatement.Any permit requirement for any of these activities is managed by GHR. locations for
any tree removal are away from the active mine areas and will not interfere with any previously
established visual screening elements,or any other elements of the mine permit.
Comment V.
Sheet C717 referenced in the application was not included as a map submission.
3M Response:This drawing was not included in the latest modification submittal since this
drawing did not change since last time it was submitted and approved by DEQ in 2017 as
revision 4 dated 1/10/17. Revision 4 is included in this response for reference only.
Comment#8:
The affected area table does not match the affected area table included in the application.
3M Response:See updated drawing PBOR-888-C-716,revision 9.Also,it was found that an error
was made in the application table.See revised version of page 4 of the application attached.
Comment#9:
Their previous 4011404, Buffer Authorization, and Buffer Determination have all expired. Please
verify that you will contact the USACE and DWR prior to impacting surface waters.
3M Response:3M will contact USACE and DWR prior to impacting surface waters.3M currently
has active 404 permit SAW-2013-02028,which expires December 31, 2027.3M has plans to
impact the streams identified in that permit.

Please do not hesitate to contact me should you have any questions or comments. I can be
reached at(651) 785-5904 or via email at tccrawford6Dmmm.com.3M greatly appreciates the
opportunity to continue working with the DEMLR.
Sincerely,
��
Trevor Crawford, PE
3M IMPD, Civil Engineer
Cc:
Blake Arnett
Andrew Miller
Attachments:
• Drawing—PBOR-888-C-716, revision 9
• Drawing—PBOR-888-C-716A, revision 1
• Drawing—PBOR-888-C-717, revision 4
• Outfall 003-004 changes.pdf
• Page 4—NC Mine Application

NORTH CAROLINA MINING State of North Carolina 1612 Mail Service Center
PERMIT APPLICATION Department of Environmental Quality Raleigh,NC 27699-1612
Division of Energy,Mineral,and Land Resources [phone]
B.MAPS
1. Clearly mark and label the location of your mining operation on six(6)copies of a 7.5-minute quadrangle and a county
highway map.These maps,in addition to six(6)copies of all mine maps and reclamation maps,must be submitted
With each permit application.
7.5-minute quadrangles may be obtained from the N.C.Geological Survey:
Mailing Address Physical Address
1612 Mail Service Center 512 N.Salisbury St.,5N Floor
Raleigh,NC 27699-1612 Raleigh,NC 27604
Http://Portal.ncdenr.org/web/Ir/geological home [phone]
County highway maps may be obtained from the N.C.Department of Transportation:
Mailing Address Physical Address
NCDOT GIS Unit NCDOT GIS Unit
1587 Mail Service Center 3401 Cad Sandburg Court
Raleigh,NC 27699-1587 Raleigh,NC 27610
httD://www.ncdot.rafiUgis [phone]
2. A table/chart must be provided on the mine map that clearly lists the approximate acreage of tailings/sediment ponds,
stockpiles,waste piles,processing areasthaul roads,mine excavations and any other major aspect of the mining
operation that is proposed to be affected/disturbed during the life of the mining permit.A tablelchart similar to the
following will be acceptable:
AFFECTED ACREAGE TABLE:
For new permits,complete only the total affected acreage column.
For modifications,complete all columns.
CATEGORY CURRENT AFFECTED PROPOSED CHANGE TO TOTAL AFFECTED
ACREAGE AFFECTEDACREAGE ACREAGE
Tailings/SedimentPonds 50.40 0.00 50.40
Stockpiles 11.30 0.00 11.30
Waste piles 371.40 0.00 371.40
Processing Areas/Haul Roads 147.80 0.00 147.80
Mine Excavations 276.10 0.00 276.10
Other(Please explain) 38.40 0.00 38.40
Total Affected Acreage 895.40 0.00 895.40
Total Permitted acreage 2,184.40 0.00 2,184.40
Revised September 21, 2021 P a r; e 4

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Existing OutFall 00g'� into pond
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Relocated Outfaii 003
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