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HomeMy WebLinkAbout20230911_ESC_Calculations MINING PLAN NARRATIVE AND CALCULATIONS for US 421 TRACT NEW HANOVER COUNTY, N.C. PREPARED FOR 421 Sand Mine LLC PO Box 100 Winnabow, NC 28479 CARO�i�i a� EAL 43166 - IN h fit Adam Grady, PE Hanover Design Services, PA 1123 Floral Parkway Wilmington, NC 28403 MINING PLAN For Tree Shaker Sand Mine 421 Sand Mine,LLC NARRATIVE NOTE: To be reviewed in conjunction with "Site Plan Tree Shaker Sand Mine", Hanover Design Services, PA, Drawings Nos. 11936 TS Sheets 1-10. PROJECT DESCRIPTION— The purpose of this project is to add additional area to the current sand mine,for the removal of borrow material. The Mining Plan is to identify measures to be implemented to minimize impacts on neighboring properties by controlling erosion during construction and by reclaiming the project site throughout the duration of excavation and once the mining is complete. The site is located off Hwy 421,3.32 miles north of 1-140. The total project area is 80.54 acres, 77.81 acres of which are proposed to be disturbed, including 59.95 for excavation.The proposed area borders the current sand mine operation. The site is wooded with fairly gently sloping topography. There are no proposed buildings or structures. The mine will operate between the hours of 7:00 a.m.to 6:00 p.m.seven days per week as needed. There is ample room for vehicles to pass along the existing access road as well as ample turn around areas on the mining parcel. SOILS— (Soils Map attached) PLANNED EROSION AND SEDIMENT CONTROL PRACTICES- 1. TEMPORARY GRAVEL CONSTRUCTION ENTRANCE Practice 6.06 Shall be installed as shown on the plan or from any existing paved roadway. Drainage is away from the road and sedimentation will be controlled with downstream practices. During wet weather it may be necessary to wash truck tires at this location. A concrete washout is also located adjacent to this area. 2. LAND GRADING Practice 6.02 Grading should be limited to areas as shown on the plans. Cut and fill slopes shall be 3:1 or flatter except where specifically indicated. 3. SEDIMENT FENCE Practice 6.62 Sediment fencing should be installed as shown on the Plan, and around any temporary stockpile areas as necessary to prevent any graded interior areas from eroding onto adjacent areas. 4. CONSTRUCTION ROAD STABILIZATION Practice 6.80 Prior to commencement of excavation, hauling roads are to be temporarily stabilized by placing sub-base course of approved stone to reduce erosion and dust. Water spraying will be utilized as necessary to control dust. 5. TEMPORARY SEEDING Practice 6.10 Any cleared or sparsely vegetative areas that cannot be brought to final grade within the stabilization time frames shall be temporarily seeded as needed to help stabilize areas. 6. PERMANENT SEEDING Practice 6.11 Permanent Seeding and/or sodding shall be conducted on areas where final grades have been achieved as soon as practical and within the time frames listed on the plans. CONSTRUCTION SCHEDULE- Indicated on Plan 1. Obtain approval of Plan and any necessary permits and hold a pre-construction conference prior to commencing any work. 2. Clearing,stumping, and construction of permanent access/haul road. 3. Clearing and stumping of access/haul road o Lake/excavation area and associated sediment fencing downstream of access/haul road. 4. Install Gravel Construction Entrance. 5. Clearing and stumping of first 5 acres of Lake/excavation area for truck turn around and stockpile location and association sediment fencing. 6. Initial excavation consisting of stripping and removal of topsoil in stockpile area(within Lake Excavation area.)Construction of earthen berm/sound barrier. Creation of Vegetative buffer. 7. Stockpiling of 0.5 to 1.0 acres of material for creation of settling/dewatering/sediment basin.This area will serve as a self-contained dewatering area/sediment basin and will have an earthen dam separating it from future excavation. As the lake/excavation grows, the dam will be removed to enlarge the settling/dewatering area/sediment basin to include recent completed excavated areas. 8. As 2 to 3 acres of excavation have been completed in the manner mentioned above, lake banks will be shaped, graded 5 to 1 slopes,mulched,seeded and landscaped as shown on the plans. 9. Once the lake is completed, temporary haul roads will be removed and reclaimed. Temporary erosion control measures will be removed.Access road to site and earthen and vegetated buffers will remain permanently. MAINTENANCE PLAN- Indicated on Plan 1. All measures to be inspected weekly and after any rainfall event and needed repairs made immediately. 2. All seeded areas shall be fertilized, mulched, and re-seeded as necessary, according to specifications provided,to maintain a suitable vegetative cover. 3. Sediment to be removed from behind silt-fence when it becomes 0.5' deep. Fencing is to be repaired as needed to maintain a barrier. 4. Construction entrance is to be maintained in a condition to prevent mud or sediment from leaving the construction site. Periodic topdressing with 2"stone may be required. Remove all objectionable material spilled,washed, or tracked onto public roadways immediately. VEGETATIVE PLAN- 1. Permanent vegetation to be established in accordance with "North Carolina Erosion and Sediment Control Planning and Design Manual", Section 6.11, latest version. See Plan for specifications.