Loading...
HomeMy WebLinkAbout2024.02.15_ADI #4_Binder 1 of 2 Piedmont Lithium Carolina, Inc. PIEDMONT 42 E Catawba St. LITHIUM Belmont, NC 28012 March 15, 2024 Mr. Adam Parr, PE NC Department of Environmental Quality Division of Energy, Mineral, and Land Resources 1612 Mail Service Center Raleigh, NC 27699-1612 Subject: Piedmont Lithium Carolinas, Inc. Carolina Lithium Project Response to Additional Information Request#4 (dated February 9, 2024) (Binder 1 of 2) Dear Mr. Parr: Piedmont Lithium Carolinas, Inc. (PLCI) submitted a North Carolina Mine Permit Application on August 30, 2021 to the Division of Energy, Mineral, and Land Resources (DEMLR). DEMLR issued an Additional Information request on October 29, 2021 (ADI#1) and PLCI responded to ADI#1 on December 15, 2021. DEMLR issued an ADI#2 on January 14, 2022 and PLCI responded to ADI#2 on June 20, 2022 followed by an extended response to ADI#2 on April 27, 2023. DEMLR issued ADI#3 on May 30, 2023 and PLCI responded to ADI#3 on January 18, 2024. DEMLR issued ADI#4 on February 9, 2024. PLCI is thankful to DEMLR and other agencies for their continued diligence and review of material. Please see the following responses to the items from ADI#4. The agency comments are in bold text and responses are provided in regular text. Two copies of this response are provided, including an electronic version. Should you have any questions or require additional information following your review of the enclosed materials, please contact me, Monique Parker, at(704) 813-2301 or mparker(a)piedmontlithium.com. Yours truly, J. Monique Parker, CSP Senior Vice President, Safety, Environment& Health Piedmont Lithium Carolinas, Inc. 1 Piedmont Lithium Carolinas, Inc. I Carolina Lithium Project Response to Mine Permit Additional Information Request#4 March 15, 2024 Binder 1 of 2 Attachments: Appendix A— MRO Comments for Piedmont Lithium Response to ADI #3 ES&C Detailed Drawings, dated 3/13/2024, attached separately(referred to as "ES&C Sheets") 2 Piedmont Lithium Carolinas, Inc. I Carolina Lithium Project Response to Mine Permit Additional Information Request#4 March 15, 2024 1. Please provide a response to the enclosed comments from the Mooresville Regional office. Please see Appendix A for PLCI's response to MRO's comments. The separately attached ES&C Detailed Drawings (dated 3/13/2024) are referred to herein as "ES&C Sheets." On the Sheet Index (ES&C Sheet OOG-001), red asterisks denote those sheets that reflect revisions per these comments. Updated skimmer design tables are also provided in Appendix A. 2. In your response to item 5 of your Additional Request for additional information dated January 18, 2023, states that you propose to evaluate real time monitoring data of the water generated from the above ground waste rock pile to inform decisions for the in-pit waste rock system and rely on 12 months of data before developing a plan for monitoring and treatment of the in-pit waste rock. The above ground waste rock pile, exposed primarily to rainwater, will exist in a different environment than the in-pit waste rock system, exposed both to rainwater and groundwater once the water table equalizes post dewatering. Data from the above ground waste rock pile may act as a supplement to the proposed in-pit waste rock system, however in order to evaluate any potential unduly adverse effects on potable groundwater supplies or standards groundwater quality, please provide a monitoring plan for the in-pit waste rock system. See Binder 2 of 2 for this response and additional information. 3 Piedmont Lithium Carolinas, Inc. I Carolina Lithium Project Response to Mine Permit Additional Information Request#4 March 15, 2024 This page intentionally left blank. 4 Piedmont Lithium Carolinas, Inc. I Response to Additional Information Request#4 Appendix A— MRO Comments for Piedmont Lithium Response to ADI#3 PIEDMONT LITHIUM Appendix A — MRO Comments for Piedmont Lithium Response to ADI #3 Piedmont Lithium Carolinas, Inc. I Response to Additional Information Request#4 Appendix A— MRO Comments for Piedmont Lithium Response to ADI#3 This page intentionally left blank. 6 Piedmont Lithium Carolinas, Inc. I Response to Additional Information Request#4 Appendix A— MRO Comments for Piedmont Lithium Response to ADI#3 MRO Comments for Piedmont Lithium Response to ADI#3 Note: The separately attached ES&C Detailed Drawings (dated 311312024) are referred to herein as "ES&C Sheets." The Mooresville Regional Office has the following comments concerning the Erosion and Sediment Control portion of the referenced application: 1. Sheet OOG-005: The NCG010000 references omit one of the zeros to the right of the "1". This comment is provided so that the reference can be corrected to avoid confusion in the future. ES&C Sheet OOG-005 has been updated to correctly reference"NCG010000". 2. Sheet OOG-005: ST228 is undersized. It appears to have been designed using 325 square feet/cfs rather than 435 square feet/cfs. This sediment trap should be sized as required by the NC Erosion and Sediment Control Planning and Design Manual requirements. ES&C Sheets OOG-005, 01CP-001, and 01CP-A001 have been updated. ST-228 is now designed and shown to reflect the requirement of 435 SF/CFS. 3. Sheet OOG-006: The required surface area for SK33 is shown incorrectly in the table. The correct "required surface area" should be 10,010 square feet, not 1010 square feet. This comment is provided so that the number can be corrected to avoid confusion in the future.The basin was sized correctly, and this error is typographic. ES&C Sheet OOG-006 has been updated to reflect the correct 'required surface area' for SK33 of 10,010 square feet. It is understood that this was a typographical error correction only as the design for SK33 was correct. 4. Sheet 01CP-001: a. The drainage area of SK248 is incorrect for the initial phase of the project. It appears that most of the drainage area shown for SK243 will drain to SK248.This skimmer basin should be sized for the maximum drainage area that it will see during the project. ES&C Sheets OOG-005, 01CP-001,and 01CP-A001 have been updated to reflect the correct drainage area for SK-243 and SK-248 for the initial phase of the project.Additional temporary diversions were added to maintain the previously calculated drainage areas for SK-243, creating a smoother transition to the Phase 2 construction conditions. An additional sediment trap, ST-229, was added to capture runoff that could not be diverted to SK-243 and SK-248. Calculations were updated and are reflected in the 'Skimmer Basin Summary Table' and `Sediment Trap Summary Table' on ES&C Sheet OOG-005. 1 Piedmont Lithium Carolinas, Inc. I Response to Additional Information Request#4 Appendix A— MRO Comments for Piedmont Lithium Response to ADI#3 b. Silt fence is needed along the eastern limit of disturbance north of SB201. Silt fence has been added along the eastern limit of disturbance north of SB-201 for Phase 1. ES&C Sheets 01 CP-001 and 01 CP-B001 have been revised to reflect the silt fence addition. 5. Sheet 01CP-B005: SB-205 is slightly too shallow. Sediment basins should have at least 2 feet of elevation difference between the bottom of the basin and the riser crest or weir. This basin slightly misses this requirement. The bottom of SB-205 has been lowered by 0.20 feet to ensure that there is at least 2 feet of elevation difference between the bottom of the basin and the riser crest. ES&C Sheets OOG-005 and 01CP- 005 have been revised to reflect this change. Calculations were updated and are reflected on these sheets. 6. Sheet 01CP-0008: SB-209 is 0.5 ft too shallow. Sediment basins should have at least 2 feet of elevation difference between the bottom of the basin and the riser crest or weir. This basin does not meet this requirement. The bottom of SB-209 has been lowered by 0.50 feet to ensure that there is at least 2 feet of elevation difference between the bottom of the basin and the riser crest. ES&C Sheets OOG-005 and 01CP- 008 have been revised to reflect this change. Calculations were updated and are reflected on these sheets. 7. General Comment: We cannot locate a table or drawing that directly compares the provided surface area elevation,the emergency spillway elevation, and the top of berm,for the skimmer basins and sediment traps.This information can be found for the Sediment Basins on the basin details, but this information does not appear readily available for the skimmer basins and sediment traps. Emergency spillway and top of berm elevations have been added to existing tables for the skimmer basins and sediment traps on ES&C Sheets OOG-005 and OOG-006. 8. Question: How will the vegetated bank area beneath the arch culverts be stabilized? This should be specified in the plan, as the vegetation beneath arch culverts typically dies due to lack of sunlight. The purpose of the arch span culverts (e.g., bottomless culverts) is to span streams without disturbance to the bed and banks of all stream crossings (Crossings #s 1 — 4), as well as minimize impact to the Federal Emergency Management Act (FEMA) special flood hazard area (SFHA) and base flood elevation (BFE)for Crossings#s 1 and 2. As noted in MRO's request for information, since there is lack of sunlight beneath the arch span culverts, bank vegetation will perish and not provide bank stability through root mass influence, and bank erosion is likely. Per MRO's request, for all arch span crossings, PLCI will be placing hard armor on the stream banks beneath the spans, which will be placed above the ordinary high water mark, up to the tops of banks and landward to the arch span walls,to cover the existing exposed ground surface to prevent erosion from occurring. 2 Piedmont Lithium Carolinas, Inc. I Response to Additional Information Request#4 Appendix A— MRO Comments for Piedmont Lithium Response to ADI#3 Crossing#s 1 and 2 are within the FEMA SFHA managed by Gaston County. Placement of hard armor in the SFHA at these locations trigger modeling of the crossing designs to determine if an increase to the base flood elevation (BFE) would occur as a result of the crossings. PLCI's objective is to not impact the BFE, and modeling is required to prove there is not an increase to the BFE—also called a No Rise—at Crossing#s 1 and 2. • Crossing #1: The placement of an articulating concrete block (ACB) system on the banks beneath the arch span at Crossing #1 (ES&C Sheets 02CO-G010, 02CO-G011) achieves MRO's request to prevent bank erosion through the placement of hard armor, as well as avoid an increase to the BFE through a No Rise modeling effort. At this crossing, riprap was evaluated as the bank armor option, but a No Rise could not be achieved with the riprap and a smoother surface was needed to prevent an increase to the BFE. See Error! Reference source not found. and Error! Reference source not found. (below) to illustrate application examples using an ACB system. 1 r� Figure 1. Example of ACB system on stream banks. Photo courtesy of Fabriform. Md1" /� r/ t ti 1� - - Figure 2. Example of channel repair. Photo courtesy of Contech. o ACB systems are an interlocking matrix of concrete blocks of uniform size, shape, and weight used for hard armor erosion control in lieu of other hard armor options (i.e., riprap). These systems provide impact-resistant material needed in high flow, or 3 Piedmont Lithium Carolinas, Inc. I Response to Additional Information Request#4 Appendix A— MRO Comments for Piedmont Lithium Response to ADI#3 high energy areas. The uniformity of ACB provides reduced surface roughness as compared to riprap, they are easy to tie into existing grade, and the installation of the systems can be done by placing "sheets" of the interlocking blocks, hand placement, or cast in-place. PLCI will use precast block systems; live concrete will not come into contact with water. o Vendors include, but are not limited to ArmorFlex, Shoretec, Fabriform, and Synthetex. PLCI has not yet chosen a specific vendor. o Manufacturers specifications for ACB system installation will be followed. • Crossing #2: The placement of riprap on the banks beneath the arch span at Crossing #2 (ES&C Sheets 02CO-L004, 02CO-L005)achieves both the request by MRO to prevent bank erosion through the placement of hard armor, as well as prevent an increase to the BFE evaluated through No Rise modeling. • Crossing #s 3 and 4: These crossings will also utilize riprap on the banks beneath the arch spans, but are not within FEMA SFHAs; therefore, No Rise modeling is not required (ES&C Sheets 01 CP-B008, 01 CP-B009, 01 CP-0010, 01 CP-0011). The limits of disturbance (LOD) and silt fence locations at Crossing #1 and Crossing #2 have been updated to accommodate the placement of hard armor beneath the arch spans (ES&C Sheets OOG- 003, OOG-004, 02CO-001, 02CO-G001, 02CO-G002, 02CO-G003, 02CO-G004, 02CO-G010, 02CO- G011, 02CO-L001, 02CO-L002, 02CO-L003, 02CO-L004, 02CO-L005). The LOD and silt fence locations at Crossing#3 and Crossing#4 have been updated to accommodate the placement of riprap beneath the arch spans (ES&C Sheets OOG-003, OOG-004, 01CP-001, 01CP- 002, 01CP-006, 01CP-007, 01CP-113001, 01CP-B002, 01CP-113008, 01CP-0001, 01CP-0002, 01CP- 0010). 4 Piedmont Lithium Carolinas, Inc. I Response to Additional Information Request#4 Appendix A— MRO Comments for Piedmont Lithium Response to ADI#3 A. 1 Concentrator Plant Skimmer Design Tables Piedmont Lithium Carolinas, Inc. I Response to Additional Information Request#4 Appendix A— MRO Comments for Piedmont Lithium Response to ADI#3 This page intentionally left blank. 6 Skimmer Design Tables for Concentrate Operations Skimmer Design Tables for Concentrate Operations,Piedmont Lithium Carolinas,Inc. Gaston County,North Carolina Table of Contents Sediment Basin -Skimmer Design Tables Skimmer Basin -Skimmer Design Tables MARSHALL MILLER&ASSOCIATES INC. Skimmer Design Tables for Concentrate Operations,Piedmont Lithium Carolinas,Inc. Gaston County,North Carolina The Erosion and Sediment Control (ESC) structures for the Concentrate Operations site will be constructed prior to disturbance within the applicable drainage area and have been designed on maximum flow and disturbance for activities within the applicable drainage area. The Sediment Basins and Skimmer Basins have been designed with a skimmer device to dewater each structure. Section 6.61—Sediment Basin and Section 6.64—Skimmer Sediment Basin of the North Carolina Department of Environmental Quality(NCDEQ) Erosion and Sediment Control Planning and Design Manual (NCDEQ Manual) dictates each basin is to be dewatered by the skimmer in 48 to 120 hours (2 to S days). The optimal dewatering time is 72 hours (3 days) per the NCDEQ Manual. The following Skimmer Design Tables for Sediment Basins and Skimmer Basins for the Concentrate Operations site are designed in accordance with the NCDEQ Manual. MARSHALL MILLER&ASSOCIATES INC. Skimmer Design Tables for Concentrate Operations,Piedmont Lithium Carolinas,Inc. Gaston County,North Carolina Sediment Basin - Skimmer Design Tables MARSHALL MILLER&ASSOCIATES INC. Skimmer Design -Sediment Basin SB-1 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 32,832 cf/day Skimmer Size 5 in Head on Orifice 0.333 ft Calculated Orifice Diameter 2.865 in Actual Orifice Diameter(1/4 inch increments) 4.251 in Actual Skimmer Drawdown Time 3.04 days Required Volume 73,260 cf Skimmer Design -Sediment Basin SB-2 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 51,840 cf/day Skimmer Size 6 in Head on Orifice 0.417 ft Calculated Orifice Diameter 3.404 in Actual Orifice Diameter(1/4 inch increments) 3.51 in Actual Skimmer Drawdown Time 3.141 days Required Volume 57,366 1 cf Skimmer Design -Sediment Basin SB-3 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 20,109 cf/day Skimmer Size 4 in Head on Orifice 0.333 ft Calculated Orifice Diameter 2.242 in Actual Orifice Diameter(1/4 inch increments) 3.251 in Actual Skimmer Drawdown Time 3.36 days Required Volume 47,304 cf Skimmer Design -Sediment Basin SB-4 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 32,832 cf/day Skimmer Size 5 in Head on Orifice 0.333 ft Calculated Orifice Diameter 2.865 in Actual Orifice Diameter(1/4 inch increments) 3.51 in Actual Skimmer Drawdown Time 3.30 days Required Volume 53,946 cf Skimmer Design -Sediment Basin SB-5 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 6,234 cf/day Skimmer Size 2.5 in Head on Orifice 0.208 ft Calculated Orifice Diameter 1.404 in Actual Orifice Diameter(1/4 inch increments) 21 in Actual Skimmer Drawdown Time 3.17 days Required Volume 13,374 cf Skimmer Design -Sediment Basin SB-6 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 9,774 cf/day Skimmer Size 3 in Head on Orifice 0.25 ft Calculated Orifice Diameter 1.680 in Actual Orifice Diameter(1/4 inch increments) 2.51 in Actual Skimmer Drawdown Time 3.23 days Required Volume 23,292 1 cf Skimmer Design -Sediment Basin SB-7 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 9,774 cf/day Skimmer Size 3 in Head on Orifice 0.25 ft Calculated Orifice Diameter 1.680 in Actual Orifice Diameter(1/4 inch increments) 2.751 in Actual Skimmer Drawdown Time 3.25 days Required Volume 28,350 cf Skimmer Design -Sediment Basin SB-8 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 20,109 cf/day Skimmer Size 4 in Head on Orifice 0.333 ft Calculated Orifice Diameter 2.242 in Actual Orifice Diameter(1/4 inch increments) 2.251 in Actual Skimmer Drawdown Time 3.04 days Required Volume 20,520 cf Skimmer Design -Sediment Basin SB-9 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 20,109 cf/day Skimmer Size 4 in Head on Orifice 0.333 ft Calculated Orifice Diameter 2.242 in Actual Orifice Diameter(1/4 inch increments) 2.251 in Actual Skimmer Drawdown Time 3.17 days Required Volume 21,366 cf Skimmer Design -Sediment Basin SB-10 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 20,109 cf/day Skimmer Size 4 in Head on Orifice 0.333 ft Calculated Orifice Diameter 2.242 in Actual Orifice Diameter(1/4 inch increments) 2.751 in Actual Skimmer Drawdown Time 3.15 days Required Volume 31,770 cf Skimmer Design -Sediment Basin SB-11 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 6,234 cf/day Skimmer Size 2.5 in Head on Orifice 0.208 ft Calculated Orifice Diameter 1.404 in Actual Orifice Diameter(1/4 inch increments) 21 in Actual Skimmer Drawdown Time 3.20 days Required Volume 13,500 cf Skimmer Design -Sediment Basin SB-12 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 51,840 cf/day Skimmer Size 6 in Head on Orifice 0.417 ft Calculated Orifice Diameter 3.404 in Actual Orifice Diameter(1/4 inch increments) 31 in Actual Skimmer Drawdown Time 3.02 days Required Volume 40,572 cf Skimmer Design -Sediment Basin SB-14 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 51,840 cf/day Skimmer Size 6 in Head on Orifice 0.417 ft Calculated Orifice Diameter 3.404 in Actual Orifice Diameter(1/4 inch increments) 4.51 in Actual Skimmer Drawdown Time 3.08 days Required Volume 92,988 1 cf Skimmer Design -Sediment Basin SB-16 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 20,109 cf/day Skimmer Size 4 in Head on Orifice 0.333 ft Calculated Orifice Diameter 2.242 in Actual Orifice Diameter(1/4 inch increments) 2.751 in Actual Skimmer Drawdown Time 3.20 days Required Volume 32,274 cf Skimmer Design -Sediment Basin SB-17 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 9,774 cf/day Skimmer Size 3 in Head on Orifice 0.25 ft Calculated Orifice Diameter 1.680 in Actual Orifice Diameter(1/4 inch increments) 2.251 in Actual Skimmer Drawdown Time 3.08 days Required Volume 18,036 cf Skimmer Design -Sediment Basin SB-18 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 32,832 cf/day Skimmer Size 5 in Head on Orifice 0.333 ft Calculated Orifice Diameter 2.865 in Actual Orifice Diameter(1/4 inch increments) 3.751 in Actual Skimmer Drawdown Time 3.27 days Required Volume 61,254 cf Skimmer Design Tables for Concentrate Operations,Piedmont Lithium Carolinas,Inc. Gaston County,North Carolina Skimmer Basin - Skimmer Design Tables MARSHALL MILLER&ASSOCIATES INC. Skimmer Design SK20 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 3,283 cf/day Skimmer Size 2 in Head on Orifice 0.167 ft Calculated Orifice Diameter 1.077 in Actual Orifice Diameter(1/4 inch increments) 1.75 in Actual Skimmer Drawdown Time 3.21 days Required Volume 9,270 cf Skimmer Design SK21 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 6,234 cf/day Skimmer Size 2.5 in Head on Orifice 0.208 ft Calculated Orifice Diameter 1.404 in Actual Orifice Diameter(1/4 inch increments) 1.75 in Actual Skimmer Drawdown Time 3.19 days Required Volume 10,296 cf Skimmer Design SK22 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 3,283 cf/day Skimmer Size 2 in Head on Orifice 0.167 ft Calculated Orifice Diameter 1.077 in Actual Orifice Diameter(1/4 inch increments) 1.75 in Actual Skimmer Drawdown Time 3.11 days Required Volume 8,982 cf Skimmer Design SK23 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 6,234 cf/day Skimmer Size 2.5 in Head on Orifice 0.208 ft Calculated Orifice Diameter 1.404 in Actual Orifice Diameter(1/4 inch increments) 2.25 in Actual Skimmer Drawdown Time 3.25 days Required Volume 17,352 cf Skimmer Design SK24 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 3,283 cf/day Skimmer Size 2 in Head on Orifice 0.167 ft Calculated Orifice Diameter 1.077 in Actual Orifice Diameter(1/4 inch increments) 1.5 in Actual Skimmer Drawdown Time 3.34 days Required Volume 7,092 cf Skimmer Design SK25 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 9,774 cf/day Skimmer Size 3 in Head on Orifice 0.25 ft Calculated Orifice Diameter 1.680 in Actual Orifice Diameter(1/4 inch increments) 2.25 in Actual Skimmer Drawdown Time 3.08 days Required Volume 17,982 cf Skimmer Design SK26 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 6,234 cf/day Skimmer Size 2.5 in Head on Orifice 0.208 ft Calculated Orifice Diameter 1.404 in Actual Orifice Diameter(1/4 inch increments) 1.5 in Actual Skimmer Drawdown Time 3.26 days Required Volume 7,722 cf Skimmer Design SK27 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 9,774 cf/day Skimmer Size 3 in Head on Orifice 0.25 ft Calculated Orifice Diameter 1.680 in Actual Orifice Diameter(1/4 inch increments) 1.75 in Actual Skimmer Drawdown Time 3.45 days Required Volume 12,186 cf Skimmer Design SK28 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 6,234 cf/day Skimmer Size 2.5 in Head on Orifice 0.208 ft Calculated Orifice Diameter 1.404 in Actual Orifice Diameter(1/4 inch increments) 1.75 in Actual Skimmer Drawdown Time 3.23 days Required Volume 10,422 cf Skimmer Design SK29 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 9,774 cf/day Skimmer Size 3 in Head on Orifice 0.25 ft Calculated Orifice Diameter 1.680 in Actual Orifice Diameter(1/4 inch increments) 2 in Actual Skimmer Drawdown Time 3.37 days Required Volume 15,552 cf Skimmer Design SK30 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 1,728 cf/day Skimmer Size 1.5 in Head on Orifice 0.125 ft Calculated Orifice Diameter 0.840 in Actual Orifice Diameter(1/4 inch increments) 1.25 in Actual Skimmer Drawdown Time 3.29 days Required Volume 4,194 cf Skimmer Design SK32 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 20,109 cf/day Skimmer Size 4 in Head on Orifice 0.333 ft Calculated Orifice Diameter 2.242 in Actual Orifice Diameter(1/4 inch increments) 2 in Actual Skimmer Drawdown Time 3.04 days Required Volume 16,218 cf Skimmer Design SK33 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 6,234 cf/day Skimmer Size 2.5 in Head on Orifice 0.208 ft Calculated Orifice Diameter 1.404 in Actual Orifice Diameter(1/4 inch increments) 2 in Actual Skimmer Drawdown Time 3.04 days Required Volume 12,798 cf Skimmer Design SK36 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 3,283 cf/day Skimmer Size 2 in Head on Orifice 0.167 ft Calculated Orifice Diameter 1.077 in Actual Orifice Diameter(1/4 inch increments) 1.5 in Actual Skimmer Drawdown Time 3.10 days Required Volume 6,588 cf Skimmer Design SK37 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 9,774 cf/day Skimmer Size 3 in Head on Orifice 0.25 ft Calculated Orifice Diameter 1.680 in Actual Orifice Diameter(1/4 inch increments) 2 in Actual Skimmer Drawdown Time 3.34 days Required Volume 15,426 cf Skimmer Design SK38 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 6,234 cf/day Skimmer Size 2.5 in Head on Orifice 0.208 ft Calculated Orifice Diameter 1.404 in Actual Orifice Diameter(1/4 inch increments) 1 in Actual Skimmer Drawdown Time 3.26 days Required Volume 3,438 cf Skimmer Design SK39 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 1,728 cf/day Skimmer Size 1.5 in Head on Orifice 0.125 ft Calculated Orifice Diameter 0.840 in Actual Orifice Diameter(1/4 inch increments) 1.25 in Actual Skimmer Drawdown Time 3.24 days Required Volume 4,140 cf Skimmer Design SK40 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 1,728 cf/day Skimmer Size 1.5 in Head on Orifice 0.125 ft Calculated Orifice Diameter 0.840 in Actual Orifice Diameter(1/4 inch increments) 1 in Actual Skimmer Drawdown Time 3.46 days Required Volume 2,8 2 61 cf Skimmer Design SK41 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 9,774 cf/day Skimmer Size 3 in Head on Orifice 0.25 ft Calculated Orifice Diameter 1.680 in Actual Orifice Diameter(1/4 inch increments) 1.75 in Actual Skimmer Drawdown Time 3.39 days Required Volume 12,006 cf Skimmer Design SK42 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 6,234 cf/day Skimmer Size 2.5 in Head on Orifice 0.208 ft Calculated Orifice Diameter 1.404 in Actual Orifice Diameter(1/4 inch increments) 2.25 in Actual Skimmer Drawdown Time 3.14 days Required Volume 16,740 cf Skimmer Design SK43 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 9,774 cf/day Skimmer Size 3 in Head on Orifice 0.25 ft Calculated Orifice Diameter 1.680 in Actual Orifice Diameter(1/4 inch increments) 2 in Actual Skimmer Drawdown Time 3.14 days Required Volume 14,508 cf Skimmer Design SK44 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 1,728 cf/day Skimmer Size 1.5 in Head on Orifice 0.125 ft Calculated Orifice Diameter 0.840 in Actual Orifice Diameter(1/4 inch increments) 1 in Actual Skimmer Drawdown Time 3.04 days Required Volume 2,484 cf Skimmer Design SK45 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 9,774 cf/day Skimmer Size 3 in Head on Orifice 0.25 ft Calculated Orifice Diameter 1.680 in Actual Orifice Diameter(1/4 inch increments) 1.5 in Actual Skimmer Drawdown Time 3.13 days Required Volume 8,136 cf Skimmer Design SK46 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 9,774 cf/day Skimmer Size 3 in Head on Orifice 0.25 ft Calculated Orifice Diameter 1.680 in Actual Orifice Diameter(1/4 inch increments) 1.25 in Actual Skimmer Drawdown Time 3.22 days Required Volume 5,814 cf Skimmer Design SK47 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 1,728 cf/day Skimmer Size 1.5 in Head on Orifice 0.125 ft Calculated Orifice Diameter 0.840 in Actual Orifice Diameter(1/4 inch increments) 1 in Actual Skimmer Drawdown Time 2.78 days Required Volume 2,268 cf Skimmer Design SK48 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 9,774 cf/day Skimmer Size 3 in Head on Orifice 0.25 ft Calculated Orifice Diameter 1.680 in Actual Orifice Diameter(1/4 inch increments) 2.25 in Actual Skimmer Drawdown Time 3.08 days Required Volume 17,982 cf Skimmer Design SK49 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 20,109 cf/day Skimmer Size 4 in Head on Orifice 0.333 ft Calculated Orifice Diameter 2.242 in Actual Orifice Diameter(1/4 inch increments) 2 in Actual Skimmer Drawdown Time 3.22 days Required Volume 17,172 cf Skimmer Design SK50 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 3,283 cf/day Skimmer Size 2 in Head on Orifice 0.167 ft Calculated Orifice Diameter 1.077 in Actual Orifice Diameter(1/4 inch increments) 1.5 in Actual Skimmer Drawdown Time 3.30 days Required Volume 7,002 1 cf Skimmer Design SK51 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 6,234 cf/day Skimmer Size 2.5 in Head on Orifice 0.208 ft Calculated Orifice Diameter 1.404 in Actual Orifice Diameter(1/4 inch increments) 2.25 in Actual Skimmer Drawdown Time 2.98 days Required Volume 15,912 cf Skimmer Design SK52 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 6,234 cf/day Skimmer Size 2.5 in Head on Orifice 0.208 ft Calculated Orifice Diameter 1.404 in Actual Orifice Diameter(1/4 inch increments) 2.25 in Actual Skimmer Drawdown Time 3.16 days Required Volume 16,830 cf Skimmer Design SK53 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 6,234 cf/day Skimmer Size 2.5 in Head on Orifice 0.208 ft Calculated Orifice Diameter 1.404 in Actual Orifice Diameter(1/4 inch increments) 2.25 in Actual Skimmer Drawdown Time 3.21 days Required Volume 17,100 cf Skimmer Design SK54 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 6,234 cf/day Skimmer Size 2.5 in Head on Orifice 0.208 ft Calculated Orifice Diameter 1.404 in Actual Orifice Diameter(1/4 inch increments) 2.25 in Actual Skimmer Drawdown Time 3.12 days Required Volume 16,650 cf Skimmer Design SK55 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 6,234 cf/day Skimmer Size 2.5 in Head on Orifice 0.208 ft Calculated Orifice Diameter 1.404 in Actual Orifice Diameter(1/4 inch increments) 2.25 in Actual Skimmer Drawdown Time 3.31 days Required Volume 17,640 cf Skimmer Design SK56 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 9,774 cf/day Skimmer Size 3 in Head on Orifice 0.25 ft Calculated Orifice Diameter 1.680 in Actual Orifice Diameter(1/4 inch increments) 1.25 in Actual Skimmer Drawdown Time 3.28 days Required Volume 5,922 cf Skimmer Design SK57 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 9,774 cf/day Skimmer Size 3 in Head on Orifice 0.25 ft Calculated Orifice Diameter 1.680 in Actual Orifice Diameter(1/4 inch increments) 2.25 in Actual Skimmer Drawdown Time 3.08 days Required Volume 17,982 cf Skimmer Design SK58 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 6,234 cf/day Skimmer Size 2.5 in Head on Orifice 0.208 ft Calculated Orifice Diameter 1.404 in Actual Orifice Diameter(1/4 inch increments) 2.25 in Actual Skimmer Drawdown Time 3.07 days Required Volume 16,362 cf Skimmer Design SK59 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 3,283 cf/day Skimmer Size 2 in Head on Orifice 0.167 ft Calculated Orifice Diameter 1.077 in Actual Orifice Diameter(1/4 inch increments) 1.25 in Actual Skimmer Drawdown Time 2.97 days Required Volume 4,374 cf Skimmer Design SK60 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 9,774 cf/day Skimmer Size 3 in Head on Orifice 0.25 ft Calculated Orifice Diameter 1.680 in Actual Orifice Diameter(1/4 inch increments) 1 in Actual Skimmer Drawdown Time 3.24 days Required Volume 3,744 cf Skimmer Design SK61 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 1,728 cf/day Skimmer Size 1.5 in Head on Orifice 0.125 ft Calculated Orifice Diameter 0.840 in Actual Orifice Diameter(1/4 inch increments) 1.25 in Actual Skimmer Drawdown Time 3.24 days Required Volume 4,140 cf Skimmer Design SK62 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 6,234 cf/day Skimmer Size 2.5 in Head on Orifice 0.208 ft Calculated Orifice Diameter 1.404 in Actual Orifice Diameter(1/4 inch increments) 2.25 in Actual Skimmer Drawdown Time 3.20 days Required Volume 17,046 cf Skimmer Design SK63 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 6,234 cf/day Skimmer Size 2.5 in Head on Orifice 0.208 ft Calculated Orifice Diameter 1.404 in Actual Orifice Diameter(1/4 inch increments) 1.25 in Actual Skimmer Drawdown Time 3.05 days Required Volume 5,022 cf Skimmer Design SK64 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 9,774 cf/day Skimmer Size 3 in Head on Orifice 0.25 ft Calculated Orifice Diameter 1.680 in Actual Orifice Diameter(1/4 inch increments) 2 in Actual Skimmer Drawdown Time 3.38 days Required Volume 15,624 cf Skimmer Design SK65 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 6,234 cf/day Skimmer Size 2.5 in Head on Orifice 0.208 ft Calculated Orifice Diameter 1.404 in Actual Orifice Diameter(1/4 inch increments) 2 in Actual Skimmer Drawdown Time 2.94 days Required Volume 12,384 cf Skimmer Design SK66 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 6,234 cf/day Skimmer Size 2.5 in Head on Orifice 0.208 ft Calculated Orifice Diameter 1.404 in Actual Orifice Diameter(1/4 inch increments) 1.75 in Actual Skimmer Drawdown Time 3.13 days Required Volume 10,098 cf Skimmer Design SK67 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 6,234 cf/day Skimmer Size 2.5 in Head on Orifice 0.208 ft Calculated Orifice Diameter 1.404 in Actual Orifice Diameter(1/4 inch increments) 2 in Actual Skimmer Drawdown Time 2.90 days Required Volume 12,222 cf Skimmer Design SK68 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 6,234 cf/day Skimmer Size 2.5 in Head on Orifice 0.208 ft Calculated Orifice Diameter 1.404 in Actual Orifice Diameter(1/4 inch increments) 2 in Actual Skimmer Drawdown Time 3.10 days Required Volume 13,068 cf Skimmer Design SK69 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 3,283 cf/day Skimmer Size 2 in Head on Orifice 0.167 ft Calculated Orifice Diameter 1.077 in Actual Orifice Diameter(1/4 inch increments) 1.5 in Actual Skimmer Drawdown Time 3.31 days Required Volume 7,020 cf Skimmer Design SK70 Desired Skimmer Drawdown Time 3 days Desired Skimmer Drawdown Rate 1,728 cf/day Skimmer Size 1.5 in Head on Orifice 0.125 ft Calculated Orifice Diameter 0.840 in Actual Orifice Diameter(1/4 inch increments) 1.25 in Actual Skimmer Drawdown Time 3.10 days Required Volume 3,960 cf Page intentionally left blank. Piedmont Lithium Carolinas, Inc. I Response to Additional Information Request#4 Appendix A— MRO Comments for Piedmont Lithium Response to ADI#3 A.2 Conversion Plant Skimmer Design Tables Piedmont Lithium Carolinas, Inc. I Response to Additional Information Request#4 Appendix A— MRO Comments for Piedmont Lithium Response to ADI#3 This page intentionally left blank. 8 Lithium Hydroxide Conversion Plant- Skimmer Calculations Skimmer Design SB-201 Req'd Vol (cf): 18,684 Desired Skimmer Drawdown Time (td)6 72 hrs Desired Skimmer Drawdown Rate (Qd) 6,228 ft3/day Skimmer Size 4.0 in Head on Orifice (H)5 0.333 ft Calculated Orifice Diameter? 2.162 in Actual Orifice Diameter$ 2.250 in Actual Skimmer Drawdown Time? 66 hrs Skimmer Design SB-202 Req'd Vol (cf): 10,170 Desired Skimmer Drawdown Time (td)6 72 hrs Desired Skimmer Drawdown Rate (Qd) 3,390 ft3/day Skimmer Size 3.0 in Head on Orifice (H)5 0.250 ft Calculated Orifice Diameter? 1.713 in Actual Orifice Diameter$ 1.750 in Actual Skimmer Drawdown Time? 69 hrs Skimmer Design SB-203 Req'd Vol (cf): 7,074 Desired Skimmer Drawdown Time (td)6 72 hrs Desired Skimmer Drawdown Rate (Qd) 2,358 ft3/day Skimmer Size 3.0 in Head on Orifice (H)5 0.250 ft Calculated Orifice Diameter? 1.429 in Actual Orifice Diameter$ 1.500 in Actual Skimmer Drawdown Time? 65 hrs 5. From Section 6.61 -Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual. 6. Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5). 7.Skimmer orifice equation: (see note 5) = %1(2310*V H) (inches) 8.Actual skimmer orifice diameter is rounded to the nearest 1/4 inch. Lithium Hydroxide Conversion Plant- Skimmer Calculations Skimmer Design SB-204 Req'd Vol (co: 10,296 Desired Skimmer Drawdown Time (td)6 72 hrs Desired Skimmer Drawdown Rate (Qd) 3,432 ft3/day Skimmer Size 3.0 in Head on Orifice (H)5 0.250 ft Calculated Orifice Diameter 1.724 in Actual Orifice Diameter$ 1.750 in Actual Skimmer Drawdown Time? 70 hrs Skimmer Design SB-205 Req'd Vol (cf): 8,100 Desired Skimmer Drawdown Time (td)6 72 hrs Desired Skimmer Drawdown Rate (Qd) 2,700 ft3/day Skimmer Size 3.0 in Head on Orifice (H)5 0.250 ft Calculated Orifice Diameter? 1.529 in Actual Orifice Diameter$ 1.500 in Actual Skimmer Drawdown Time? 75 hrs Skimmer Design SB-206 Req'd Vol (cf): 9,900 Desired Skimmer Drawdown Time (td)6 72 hrs Desired Skimmer Drawdown Rate (Qd) 3,300 ft3/day Skimmer Size 2.5 in Head on Orifice (H)5 0.208 ft Calculated Orifice Diameter? 1.770 in Actual Orifice Diameter$ 1.750 in Actual Skimmer Drawdown Time? 74 hrs 5. From Section 6.61 -Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual. 6. Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5). 7.Skimmer orifice equation: n - (see note 5) D= V'Qd 1(2310*v{H) (inches) 8.Actual skimmer orifice diameter is rounded to the nearest 1/4 inch. Lithium Hydroxide Conversion Plant- Skimmer Calculations Skimmer Design SB-207 Req'd Vol (cf): 8,280 Desired Skimmer Drawdown Time (td)6 72 hrs Desired Skimmer Drawdown Rate (Qd) 2,760 ft3/day Skimmer Size 3.0 in Head on Orifice (H)5 0.250 ft Calculated Orifice Diameter? 1.546 in Actual Orifice Diameter$ 1.500 in Actual Skimmer Drawdown Time? 76 hrs Skimmer Design sB-208 Ph 1 Req'd Vol (cf): 10,170 Desired Skimmer Drawdown Time (td)6 72 hrs Desired Skimmer Drawdown Rate (Qd) 3,390 ft3/day Skimmer Size 3.0 in Head on Orifice (H)5 0.250 ft Calculated Orifice Diameter? 1.713 in Actual Orifice Diameter$ 1.750 in Actual Skimmer Drawdown Time? 69 hrs Skimmer Design sB-209 Ph 1 Req'd Vol (cf): 11,520 Desired Skimmer Drawdown Time (td)6 72 hrs Desired Skimmer Drawdown Rate (Qd) 3,840 ft3/day Skimmer Size 4.0 in Head on Orifice (H)5 0.333 ft Calculated Orifice Diameter? 1.697 in Actual Orifice Diameter$ 1.750 in Actual Skimmer Drawdown Time? 68 hrs 5. From Section 6.61 -Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual. 6. Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5). 7.Skimmer orifice equation: n - (see note 5) D= V'Qd 1(2310*v{H) (inches) 8.Actual skimmer orifice diameter is rounded to the nearest 1/4 inch. Lithium Hydroxide Conversion Plant- Skimmer Calculations Skimmer Design sB-210 Ph 1 Req'd Vol (cf): 19,170 Desired Skimmer Drawdown Time (td)6 72 hrs Desired Skimmer Drawdown Rate (Qd) 6,390 ft3/day Skimmer Size 4.0 in Head on Orifice (H)5 0.333 ft Calculated Orifice Diameter? 2.189 in Actual Orifice Diameter$ 2.250 in Actual Skimmer Drawdown Time? 68 hrs 5. From Section 6.61 -Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual. 6. Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5). 7.Skimmer orifice equation: (see note 5) —� Qd 1(2310*1�H 1 (incheti) 8.Actual skimmer orifice diameter is rounded to the nearest 1/4 inch. Lithium Hydroxide Conversion Plant- Skimmer Calculations Skimmer Design SK-240 Ph 2 Req'd Vol (cf): 2,790 Desired Skimmer Drawdown Time (td)6 72 hrs Desired Skimmer Drawdown Rate (Qd) 930 ft3/day Skimmer Size 2.0 in Head on Orifice (H)5 0.167 ft Calculated Orifice Diameter? 0.993 in Actual Orifice Diameter$ 1.000 in Actual Skimmer Drawdown Time? 71 hrs Skimmer Design SK-241 Ph 1 Req'd Vol (cf): 4,644 Desired Skimmer Drawdown Time (td)6 72 hrs Desired Skimmer Drawdown Rate (Qd) 1,548 ft3/day Skimmer Size 2.5 in Head on Orifice (H)5 0.208 ft Calculated Orifice Diameter? 1.212 in Actual Orifice Diameter$ 1.250 in Actual Skimmer Drawdown Time? 68 hrs Skimmer Design SK-241 Ph 2 Req'd Vol (cf): 2,988 Desired Skimmer Drawdown Time (td)6 72 hrs Desired Skimmer Drawdown Rate (Qd) 996 ft3/day Skimmer Size 2.5 in Head on Orifice (H)5 0.208 ft Calculated Orifice Diameter? 0.972 in Actual Orifice Diameter$ 1.000 in Actual Skimmer Drawdown Time? 68 hrs 5. From Section 6.61 -Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual. 6. Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5). 7.Skimmer orifice equation: n - (see note 5) D= V'Qd 1(2310*v{H) (inches) 8.Actual skimmer orifice diameter is rounded to the nearest 1/4 inch. Lithium Hydroxide Conversion Plant- Skimmer Calculations Skimmer Design SK-242 Ph 2 Req'd Vol (cf): 2,700 Desired Skimmer Drawdown Time (td)6 72 hrs Desired Skimmer Drawdown Rate (Qd) 900 ft3/day Skimmer Size 2.0 in Head on Orifice (H)5 0.167 ft Calculated Orifice Diameter? 0.976 in Actual Orifice Diameter$ 1.000 in Actual Skimmer Drawdown Time? 69 hrs Skimmer Design SK-243 Ph 1 Req'd Vol (cf): 4,068 Desired Skimmer Drawdown Time (td)6 72 hrs Desired Skimmer Drawdown Rate (Qd) 1,356 ft3/day Skimmer Size 3.0 in Head on Orifice (H)5 0.250 ft Calculated Orifice Diameter? 1.084 in Actual Orifice Diameter$ 1.000 in Actual Skimmer Drawdown Time? 85 hrs Skimmer Design SK-243 Ph 2 Req'd Vol (cf): 3,420 Desired Skimmer Drawdown Time (td)6 72 hrs Desired Skimmer Drawdown Rate (Qd) 1,140 ft3/day Skimmer Size 3.0 in Head on Orifice (H)5 0.250 ft Calculated Orifice Diameter? 0.993 in Actual Orifice Diameter$ 1.000 in Actual Skimmer Drawdown Time? 71 hrs 5. From Section 6.61 -Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual. 6. Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5). 7.Skimmer orifice equation: n - (see note 5) D= V'Qd 1(2310*v{H) (inches) 8.Actual skimmer orifice diameter is rounded to the nearest 1/4 inch. Lithium Hydroxide Conversion Plant- Skimmer Calculations Skimmer Design SK-244 Req'd Vol (cf): 4,050 Desired Skimmer Drawdown Time (td)6 72 hrs Desired Skimmer Drawdown Rate (Qd) 1,350 ft3/day Skimmer Size 2.5 in Head on Orifice (H)5 0.208 ft Calculated Orifice Diameter? 1.132 in Actual Orifice Diameter$ 1.250 in Actual Skimmer Drawdown Time? 59 hrs Skimmer Design SK-245 Ph 1 Req'd Vol (cf): 5,580 Desired Skimmer Drawdown Time (td)6 72 hrs Desired Skimmer Drawdown Rate (Qd) 1,860 ft3/day Skimmer Size 2.0 in Head on Orifice (H)5 0.167 ft Calculated Orifice Diameter? 1.404 in Actual Orifice Diameter$ 1.500 in Actual Skimmer Drawdown Time? 63 hrs Skimmer Design SK-245 Ph 2 Req'd Vol (cf): 2,070 Desired Skimmer Drawdown Time (td)6 72 hrs Desired Skimmer Drawdown Rate (Qd) 690 ft3/day Skimmer Size 2.0 in Head on Orifice (H)5 0.167 ft Calculated Orifice Diameter? 0.855 in Actual Orifice Diameter$ 0.750 in Actual Skimmer Drawdown Time? 94 hrs 5. From Section 6.61 -Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual. 6. Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5). 7.Skimmer orifice equation: n - (see note 5) D= V'Qd 1(2310*v{H) (inches) 8.Actual skimmer orifice diameter is rounded to the nearest 1/4 inch. Lithium Hydroxide Conversion Plant- Skimmer Calculations Skimmer Design SK-246 Ph 1 Req'd Vol (cf): 5,040 Desired Skimmer Drawdown Time (td)6 72 hrs Desired Skimmer Drawdown Rate (Qd) 1,680 ft3/day Skimmer Size 2.5 in Head on Orifice (H)5 0.208 ft Calculated Orifice Diameter? 1.263 in Actual Orifice Diameter$ 1.250 in Actual Skimmer Drawdown Time? 73 hrs Skimmer Design SK-247 Ph 1 Req'd Vol (cf): 3,420 Desired Skimmer Drawdown Time (td)6 72 hrs Desired Skimmer Drawdown Rate (Qd) 1,140 ft3/day Skimmer Size 2.5 in Head on Orifice (H)5 0.208 ft Calculated Orifice Diameter? 1.040 in Actual Orifice Diameter$ 1.000 in Actual Skimmer Drawdown Time? 78 hrs Skimmer Design SK-248 Ph 1 Req'd Vol (cf): 4,896 Desired Skimmer Drawdown Time (td)6 72 hrs Desired Skimmer Drawdown Rate (Qd) 1,632 ft3/day Skimmer Size 2.5 in Head on Orifice (H)5 0.208 ft Calculated Orifice Diameter? 1.245 in Actual Orifice Diameter$ 1.250 in Actual Skimmer Drawdown Time? 71 hrs 5. From Section 6.61 -Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual. 6. Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5). 7.Skimmer orifice equation: n - (see note 5) D= V'Qd/(2310*v{H) (inches) 8.Actual skimmer orifice diameter is rounded to the nearest 1/4 inch. Lithium Hydroxide Conversion Plant- Skimmer Calculations Skimmer Design SK-249 Ph 1 Req'd Vol (cf): 4,320 Desired Skimmer Drawdown Time (td)6 72 hrs Desired Skimmer Drawdown Rate (Qd) 1,440 ft3/day Skimmer Size 2.5 in Head on Orifice (H)5 0.208 ft Calculated Orifice Diameter? 1.169 in Actual Orifice Diameter$ 1.250 in Actual Skimmer Drawdown Time? 63 hrs 5. From Section 6.61 -Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual. 6. Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5). 7.Skimmer orifice equation: — (see note 5) D=ry V' Qd/(2310*AH) (inches) 8.Actual skimmer orifice diameter is rounded to the nearest 1/4 inch. Page intentionally left blank.