NCG020818_Monitoring Exemption Reference in NCG02_6/7/2019

Permit No. NCG020000
PART IV — MONITORING, CONTROLS, AND LIMITATIONS FOR PERMITTED
DISCHARGES
SECTION A: STORMWATER DISCHARGES — ANALYTICAL MONITORING
REQUIREMENTS
Regulated industrial stormwater discharges are discharges of stormwater-only flows from
mining activity areas, including (but not limited to) areas of mine excavation, other land
disturbance, process areas, and vehicle maintenance. This section does not apply to wastewater
discharges from mine dewatering and process areas. Analytical monitoring for stormwater
discharges shall be performed for parameters as specified in Tables 1 through 3.
Monitoring Exemption
Analytical monitoring is not required for any basin or pond designed to contain the 25-year, 24-
hour storm (see Part VI, Definitions) without discharging, and that can regain capacity to hold such
an event within five (5) days' time through means other than discharge to surface waters. A basin
or pond that meets this provision is considered a non -discharging stormwater control measure.
All analytical monitoring shall be performed during a measurable storm event at each stormwater
discharge outfall (SDO). Only SDOs discharging stormwater associated with industrial activity
must be sampled (See Definitions).
A measurable storm event for the purposes of this General Permit is a storm event that results
in an actual discharge from the permitted site outfall. The time between this storm event and
the previous measureable storm event must be at least 48 hours. See Definitions.
Table 1 Analytical Monitoring Requirements for Stormwater Discharges from Mining
Activities
Discharge
Characteristics
Units
Measurement
Frequencyl
Sample
Type2
Sample
Location3
Settleable Solids
MI/1
Semi-annual
Grab
SDO
Total Suspended Solids
mg/1
Semi-annual
Grab
SDO
Turbid,ty4
NTU
I Semi-annual
Grab
SDO, U & D4
Total Rainfalls
inches
I Semi-annual
--
--
Footnotes:
1. Measurement Frequency: Twice per year (unless other provisions of this permit require monthly
sampling) during a measureable storm event, until either another permit is issued for this facility or
until this permit is revoked or rescinded. If the facility is monitoring monthly because of Tier Two or
Three response actions under the previous General Permit, the facility shall continue a monthly
monitoring and reporting schedule in Tier Two or Tier Three status until relieved by the provisions of
this permit or the Division.
2. Grab samples shall be collected within the first 30 minutes of discharge. Where physical separation
between outfalls prevents collecting all samples within the first 30 minutes, the permittee shall begin
sampling within the first 30 minutes, and shall continue until completed.
3. Sample Location: Samples shall be collected at each stormwater discharge outfall (SDO) unless
representative outfall status (ROS) has been granted. A copy of the Division's letter granting ROS shall be
kept on site with the SPPP.
4. Turbidity must be monitored at the stormwater discharge outfall (SDO). In addition to the SDO, the
permittee may elect to also monitor turbidity in the receiving water, directly upstream (U) and
Part IV Page 1 of 12 Pages