20220722_ADI_Received

From: James Izzell
To: Parr, Adam
Subject: [External] simpson hocutt mine 16-82
Date: Friday, July 22, 2022 2:28:32 PM
Attachments: o&m Nan.odf
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Adam;
As a follow-up to my email yesterday, I am attaching the Pumping Operation and
Monitoring Plan that is part of the NPDES Permit application associated with
modification of permit #16-82, Simpson-Hocutt Mine. I believe this will assist you in
your review of the modification application.
Please let me know if you need any additional information.
James Izzell
Carolina Geological Services, Inc

This PUMPING OPERATION AND MONITORING PLAN was prepared in
accordance with the requirements specified in the National Pollutant Discharge
Elimination System (NPDES) General Permit for Mining (NCG020), and specifically
as applied in the Certificate of Coverage for this location:
Simpson Hocutt Mine
NC Mining Permit # 16-82
Certificate of Coverage
NCG020***
Thomas Simpson Construction Co.
Roberts Road
Newport, Carteret County, NC
June 27, 2022
This plan is designed to satisfy the requirements of Part G, Section 2 of the
NPDES General Permit NCG0200.

Background:
The NPDES General Stormwater Permit for Mining (NCG020000) addresses
impacts of mine dewatering wastewater pumping and discharge on surrounding areas,
including potential impacts to wetlands. The NPDES Permit requires that the mine have
a site specific plan for, 1) Groundwater monitoring strategies to demonstrate the effect of
pumping, 2) Detailed plans to maintain the surrounding hydrology that protects the
affected streams and wetlands, 3) Monitoring to demonstrate compliance, and 4) The
pumping regime deemed necessary to protect affected streams and wetlands
In order to develop these plans, detailed studies must be done to understand the
site -specific parameters. First, any wetlands that may be potentially impacted must be
delineated according to US Army Corps of Engineers criteria. Second, a study of
potential impacts of groundwater levels must be conducted. This should include a
detailed examination of soil types, permeability, and various zones of groundwater within
the zone of influence. Third, based on the groundwater data, an assessment of potential
impacts to the wetlands by mine dewatering should be estimated. Finally, based on the
potential impact, a plan should be developed to limit as well as monitor the potential
impacts to the wetlands.
Site description:
The Simpson Hocutt mine is located on Roberts Road, east of Newport, NC It is
located within the USGS Hydrologic Unit 03020301, White Oak River Basin. The mine
excavation will encompass 5 acres. Natural groundwater levels within the sand mine are
within 5 feet of the surface. The sand deposit being mined is a coastal deposit
consisting of sediments, ranging from a silty fine to medium grained sand. The
excavation will be reclaimed as a pond. The Mine Plan as submitted for the Mining
Permit Application is attached.
Wetland description:
The wetlands adjacent to the Simpson Hocutt Mine were delineated in 2017 as
part of the original mine permitting. The wetland area is confined to the northern end of
the property, along and adjacent to the Southwest Prong Newport River. The wetland is
broadly classified as a Freshwater Forested/Shrub Wetland. It is further classified as a
Palustrine System, which includes all nontidal wetlands dominated by trees, shrubs,
persistent emergents, emergent mosses or lichens. Surface water is present for
extended periods especially early in the growing season but is absent by the end of the
growing season in most years. The water table after flooding ceases is variable,
extending from saturated to the surface to a water table well below the ground surface.
Natural hydration of the wetlands is accomplished by regular flooding and natural
fluctuation of the river, as well as natural surface drainage from rainfall.

Pumping and mine dewatering:
This sand deposit is typical of other deposits in this area. The groundwater table
is several feet below the original ground surface, but above the total depth of the
excavation. Therefore, some groundwater is occasionally pumped from the mining area.
Goundwater and stormwater will be collected within a large sump area in the mined
area. The dewatering pump intake floats on the surface of the collected water,
preventing any sediment from leaving the mining area. Water is then pumped to a
constructed 30 foot by 60 foot basin with a rock filter to further allow any sediment to
settle. The basin overflow flows into the adjacent wetland via sheet flow. Based on the
volume of the pump and projected water levels, it is anticipated that a maximum of
325,000 gallons per day maximum will be pumped from the pit.
Impact of dewatering on adjacent wetlands:
The wetlands that have been identified in the area of the sand mine are located
within the lower elevation areas that are subject to occasional flooding of the Southwest
Prong Newport River. The natural hydration of the wetlands is accomplished by
occasional flooding of the river, natural surface runoff, and rainfall, and not from the
deeper groundwater found in the sand mine. Therefore, the mine dewatering will have
no impact on adjacent wetlands. In addition, the water that is pumped from the mining
area will directly discharge into wetlands on the same property. Therefore, the
dewatering activity will actually enhance the wetland environment, providing hydration
even during dry periods.
Monitoring:
Based on the observed disconnection between the water within the mining area
and the surrounding wetlands, it is anticipated that any potential dewatering at this mine
will have no impact on the adjacent wetlands. In order to confirm that there is no impact
to the wetlands, a monitoring plan should be established as a precaution.
1. Mine dewatering wastewater discharges should be quantitatively and qualitatively
monitored according to requirements of the NPDES permit. See the "Monitoring
Requirements" in the Stormwater Pollution Prevention Plan.
2. The Discharge Point should be examined weekly to make sure that it is functioning as
designed and that no sediment has discharged into the adjacent wetlands.
3. A written record shall be kept of pumping times and rates. A record of rainfall shall
also be kept in the Stormwater Pollution Prevention Plan.
5. The wetland vegetation in the ditches should be inspected at least quarterly. If any
vegetation appears to be distressed, an investigation should be conducted to determine
the cause.