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Home My WebLink About20080868 Ver 2_R-13 and R-14 GW Monitoring Plan_20200507Alutrien- Feeding the Future - Certified Mail May 7, 2020 Mr. Tom Steffens U.S. Army Corps of Engineers Washington Regulatory Field Office 2407 West Sth Street Washington, North Carolina 27889 Mr. Paul Wojoski North Carolina Dept. of Environmental Quality Division of Water Resources Wetlands, Buffers, Stormwater Compliance/Permits Unit 1650 Mail Service Center Raleigh, NC 27699-1650 Mr. David May NCDEQ— Division of Water Resources 943 Washington Square Mall Washington, North Carolina 27889 Dear Mr. Steffens, Mr. Wojoski and Mr. May: Enclosed please find a CD of a plan titled "R13 and R14 Groundwater Monitoring Plan, PCS Phosphate Company, Inc., Beaufort County, NC". This plan is a requirement of 404 Permit No. SAW-2001-10096 Special Condition Q, issued June 10, 2009, and 401 Water Quality Certification No. 2008-0868, version 2.0 Special Condition 12, issued January 15, 2009. This plan is an addendum and continuation of the groundwater monitoring plan for the R12 reclamation area submitted on June 10, 2016 and approved by DWR on September 17, 2017. If you have any questions regarding this plan, please email me at jeff.furness@nutrien.com. We look forward to gaining agency approval so that implementation of the plan can begin. Si er�eelly, /1 llpt (1, �J, r-%o Je rey C. urness Senior Scientist Enclosure PC: Anthony Scarbraugh — DWR, Washington w/CD RobJenner w/CD 23-16 w/CD 23-01-004-29 w/CD 1530 NC Hwy 306 South, Aurora, NC USA 27806 nutrien.com 1 Effective January 1, 2018, PCs Phosphate Company, Inc. is an indirect subsidiary of Nutrien Ltd. PCS Phosphate Company, Inc. remains the legal operating entity and permittee. R13 and R14 Groundwater Monitoring Plan PCS Phosphate Company, Inc. Beaufort County, NC PCS Phosphate Company, Inc. (PCS Phosphate) operates a phosphate mining operation near the town of Aurora in Beaufort County, North Carolina. The mining operation has been active since 1965, and it provides the raw material used for processing in the PCS Phosphate Aurora chemical facilities. Fertilizers are the primary product produced at the site. Mining of the phosphate ore is accomplished by open pit mining methods. At PCS Phosphate, the by-products clay fines (passing a No. 200 Standard US Sieve Size), from milling the phosphate ore, and gypsum, from the production of phosphoric acid, are blended together. This resulting blend has been successfully used as backfill in reclamation areas since 1986. In the next several years, PCS Phosphate will begin filling its future reclamation areas known as R13 and R14 on what is known as the NCPC Tract. The R13 and R14 areas will contain the gypsum -clay blend. Prior to introducing gypsum/clay blend in the reclamation of any mined area, PCS Phosphate is required to submit to the U.S. Army Corps of Engineers (USACOE) and the NC Department of Environmental Quality Division of Water Resources (NCDEQ-DWR) a groundwater monitoring plan for areas covered by USACOE Permit No. 200110096 and NCDEQ-DWR Water Quality Certification No. 3771 (#2008-0868,version 2.0). The Coastal Plain Province is underlain by marine, estuarine, and terrestrial sediments (up to 10,000 feet thick at Cape Hatteras). The mine property is underlain by approximately 2,500 feet of Cretaceous to Recent -aged sediments and sedimentary rocks that were deposited on top of pre -Mesozoic aged crystalline basement rocks. Overlying the Cretaceous sediments is a sequence of Cenozoic -aged sediments of dominantly marine origin. These include significant beds of sand, shelly clay and fossiliferous sandy limestone. The Cenozoic sediments have been hydrostratigraphically subdivided into three aquifers locally, including (from deep to shallow): the Castle Hayne Aquifer, the Pungo River Aquifer, and the Surficial/Yorktown Aquifer. These aquifers contain fresh water in inland areas, and they are sources for local and regional water supplies. Table 1 lists the principal local aquifers and Formations that occur beneath the PCS Phosphate mine and describes the characteristics of each. We propose five groundwater monitoring well locations around R13 and four locations around R14 (Figures 1 and 2). Each site will consist of a well drilled into the upper Castle Hayne Formation, generally deeper than -160 MSL, and a well drilled into the surficial Yorktown Formation within the range of -30 to -90 MSL. Well locations are approximate, and exact final well locations will be based on logistics and accessibility in the field. Each well will be drilled outside the footprint of the planned reclamation areas in unmined land. Areas to the north of the R-13 and R14 reclamation areas are mined out and contain either gypsum -clay blend or overburden. The 2-inch diameter wells will be constructed and installed to the same specifications as were outlined in our June 10, 2016 submission of the R12 groundwater monitoring plan, which was approved by DWR on September 1, 2017. Groundwater samples will be collected monthly and analyzed for the parameters listed on Table 2. Table 1. Local Aquifers near the PCS Phosphate Mine Aquifer Formations and Ages Character and Use This aquifer occurs as a veneer (up to 70 feet Surficial Sediments and thick) of sandy to clayey sediments, locally o(Pleistocene James City Formation fossiliferous with shell hash. The aquifer to Recent) covers the entire County, except in areas 1. where deeply incised streams and rivers cut >. into underlying units. Clays within the unit tend to serve as confining layers and restrict recharge to underlying aquifers. The aquifer is not tE Yorktown Formation currently used as a significant groundwater � (Pliocene) source. It may be used sporadically for irrigation and private residential water supply. This fine-grained unit is composed of interbedded phosphatic clays, diatomaceous Pungo River Formation clays, phosphatic limestones, silty claystones, L (Miocene) coquinas, calcareous clays, and phosphatic o '9 sands. It is not a major water -producing a a aquifer, but can supply usable quantities of a water to some local wells. Phosphate from this formation is obtained by open -pit mining at the PCS Phosphate Mine. The Castle Hayne Formation is a sandy y E Castle Hayne Formation limestone and is characteristically highly y (Eocene) fossiliferous (molluscan mold to bryozoan/ >, _ echinoid skeletal). The aquifer typically has a hard cap rock of well -indurated limestone. °; w The upper limestone unit has very high permeability. Middle to lower sections of the a unit may be less indurated and have higher sand and clay contents. co C � m Table 2. Groundwater Analytes: Units, Detection Limits, and 2L Standard Parameter Units 21-Standard Detection Limit pH sU 6.5-8.5 0 -14 Nitrate Nitrogen as N mg/L 10 0.04 Total Phosphorus as P mg/L - 0.04 Chloride mg/L 250 1 Fluoride mg/L 2 0.10 Total Dissolved Residue mg/L 500 10 Sulfate mg/L 250 5 Arsenic ug/L 10 5 Arsenic, Total Dissolved ug/L 10 5 Cadmium ug/L 2 1 Cadmium, Total Dissolved ug/L 2 1 Chromium ug/L 10 5 Chromium, Total Dissolved ug/L j 10 5 Lead ug/L 15 5 Lead, Total Dissolved ug/L 15 5 Nickel ug/L 100 10 Nickel, Total Dissolved ug/L 100 10 Sodium ug/L - 2500 Zinc ug/L 1000 10 Zinc, Total Dissolved ug/L 1000 10 Gross Alpha pCi/L 15 Varies Radium-226 pCi/L Varies Radium-228 pCi/L Varies Uranium pCi/L Varies