Raleigh Regional Office Comments

Raleigh Regional Office Comments
1. During our site visit on April 4, 2024, Mr. Stone stated that the mining map provided in
the permit application does not accurately reflect the intended clearing and mining
boundaries because the plans show a larger mining boundary footprint than what is
anticipated. DEMLR staff were informed that there are no plans to mine beyond the
parcels labeled#7,#13,#20, and #21. Clearing is also anticipated across the parcels
labeled#4 and#18.Therefore, we recommend requesting they submit a revised mine
map that reflects accurate mining boundaries, vegetative buffers, screening, clearing
limits, etc.
2. Provide additional erosion and sediment control measures along the northern boundary
of the site adjacent to the riparian buffer and stream to ensure adequate protection in
this critical area.
3. The sediment basin calculations provided are based on a 10-year storm. Provide design
calculations for peak discharge rate for the 25-year storm. Provide all supporting data
for the computation methods used (rainfall data for required storm events,time of
concentration/storm duration, and runoff coefficients used).
4. Sediment Basin A is labeled but not completely shown on plan Sheet 3. Show the
entirety of the basin's dimensions and the accompanying erosion control measures
(baffles, skimmer, emergency spillway, diversion ditches, inlet/outlet protection, etc.).
5. The baffles shown for Basin E are spaced too closely. Target percentage of surface area
for each section of the baffle is as follows: inlet zone 25%,first cell 25%, second cell
25%, outlet zone 25%. Relocate diversion ditch outlet and/or baffle configuration to
satisfy this requirement.
6. Include the baffles within the footprint of the skimmer basin for all basins (A, B, and D)
on the plan sheet. Flow is required to pass through a minimum of three baffles before
reaching the skimmer cell.
7. Identify the location of the emergency spillway for Basin B on the plan sheet. Please
note,the skimmer outlet structures/conduits should not be placed within the footprint
of the emergency spillway.
8. The Skimmer Basin plan detail shows the skimmer pipe running through the emergency
spillway structure. Please note, the skimmer outlet structures should not be placed
within the footprint of the emergency spillway. Revise the plan detail shown for the
standard skimmer basin to include an approved plan detail for the skimmer and
emergency spillway.
9. Discharge into the skimmer basin should enter before the baffle farthest from the
skimmer(inlet zone.) Sheet flow into basins is discouraged. Discharge water into the
basin in a manner to prevent erosion. Provide a stable conveyance from diversions into
basins (i.e. rip rap lined channel, properly-sized slope drain,tarp, etc.).
10. Include the basin surface area dimensions, depth, side slopes, dam height, embankment
width, length of emergency spillway, skimmer size, skimmer orifice size, and dewatering
time on the plan sheets where they occur.

11. Provide stable conveyance (extend pipe, provide tarp or other acceptable practice)from
outlet of skimmer to perimeter silt fence/silt fence outlet.
12. Provide adequate measures in diversion ditches/swales to limit excess erosion (i.e.
wattles or rock check dams) and show them on the plan sheet with adequate symbology
or labels.
13. There are no plan details shown for the silt bags, slope drains,tracking methods,
downpipes, and inlet protection. Provide a plan detail, construction specifications, and
specific maintenance requirements for all proposed sediment and erosion control
structures included on the plan. Recommend placing maintenance requirements with
the associated construction detail.
14. Provide a plan detail and construction specifications for the silt fence and silt fence
outlet that complies with the skirt trench requirements per the Erosion and Sediment
Control Planning and Design Manual.The skirt is to be trenched in, at a minimum, 8
inches vertically and 4 inches horizontally. Include the maintenance requirements for
the silt fence and silt fence outlets.
15. Provide a detailed/specific construction sequence related to erosion and sediment
control that addresses all phases of construction on the plan sheets.
16. Include the rip rap apron outlet dimensions on the plan sheets and show outlet
protection for each down pipe on the reclamation plan.
17. Provide the tacking method and rates within the Seeding Specifications on Sheet 9.
18. Specify that a staged seeding approach will be used on slopes within the construction
sequence and the Seeding Specifications on Sheet 9.
19. Please verify that mining boundary limit markers will be marked on 100-ft spacing.
Please include this verification as a detail on the construction sequence on the mine
maps.