20080868 Ver 2_Creeks Vegetation Monitoring Letter_20170921

PQtashCorp®
Helping Nature Provide P6tashCorp - Aurora
Certified Mail
September 12, 2017
Mr. Tom Steffens
U.S. Army Corps of Engineers
Washington Regulatory Field Office
2407 West 50' Street
Washington, North Carolina 27889
Mr. Anthony Scarbraugh
NC Division of Water Resources
Department of Environmental Quality
943 Washington Squareinall
Washington, North Carolina, 27889
Re: Clarification on Vegetation Monitoring for Creeks Study
Dear Mr. Steffens and Mr. Scarbraugh:
According to the PCS Phosphate creeks monitoring plan developed with the assistance of the
Science Panel as required by the Corps' and DWR's 2009 permit conditions, annual
monitoring of vegetation is not necessary. Accordingly, since 2012, vegetation monitoring
has occurred on a less frequent basis. Because of a perceived "lag effect" for vegetative
response to changes in the drainage basin hydrologic regime, agencies and the Science Panel
agreed that no vegetation monitoring should occur during a transition year (when the mine
moves across basin; could be more than one year duration for some creeks) or during the first
year following the transition year(s). Initial data collection includes five years of baseline
(either pre -Alt E or pre -Mod Alt L) when possible.
At the August 2017 Science Panel meeting, PCS proposed that four sequential years of initial
post -Mod Alt L data be collected and sought guidance to establish a suitable interval before
the next post -.Mod Alt L data are collected. Agencies were concerned about Huddles Cut
West due to the instability in the Croatan Clay, a discontinuous layer in the surficial geology,
which caused several small depressions in 2012; agencies did not want to miss potential
changes to vegetation in those areas and were reluctant to have a data gap. After reassurance
from PCS that 1) the mine headwall was no longer exposed due to reclamation fill and 2) the
area has been stable since 2012, the agencies agreed that after four years of post -Mod Alt L
data have been collected, the next year can be skipped.
PCS further proposes that after the initial four-year post -Mod Alt L data collection and
skipping the 5`b year in each creek, vegetation monitoring would occur in each creek every
other year until such time that the agencies and/or Science Panel members deem otherwise.
1530 NC Hwy 306 South, Aurora, NC USA 27806 T [phone]
Pota0hC0gL I WWWPotashcorpcom

Please let me know if this clarification regarding vegetation monitoring within the overall
creeks study is acceptable. If you have any questions, please call me at [phone],
or e-mail me at ifumess@,potashcoLp.com.
Sincerely,
alJ eyfFurness
Senior Scientist
PC: S. Cooper/J. Berger, CZR Incorporated
23-01-004-29
23-16-009