Sep 17, 2012
Stormwater Permit
The current NPDES General Permit NCG120000 (Permit) for landfills will expire on October 31, 2012. The comment period ends on October, 4 2012 with the new Permit set to issue on October 19, 2012 (Effective November 1, 2012). The following is a summary of the major differences between this draft Permit and the current Permit set to expire.
1.0 Monitoring Parameters
Qualifying discharges from vehicle maintenance areas will now include analytical monitoring for Total Petroleum Hydrocarbons (TPH) instead of the previous Oil & Grease analysis. This is based on the assessment that TPH is more specific for petroleum hydrocarbons than Oil & Grease. There should be no cost difference between these analyses.
Total Suspended Solids (TSS) is a parameter monitored in the current Permit; however, lower TSS thresholds have been implemented for discharges in certain water designations (ORW, HQW, trout, and primary nursery area (PNA) waters). Benchmark values are discussed below.
No other change is proposed for monitoring parameters.
2.0 Measurable Storm Event
The draft Permit introduces an updated definition of what storm event should be sampled. The term “representative storm event” has been replaced by “measurable storm event.” The “measurable storm event” is an event that results in an actual discharge, rather than an event with a rainfall measuring 0.1 inches or more. To qualify as a measurable storm event, previous storms must have been at least 72 hours prior. Samples must be collected within the first 30 minutes of discharge.
3.0 Adverse Weather
The draft Permit defines adverse weather conditions and allows the permittee to forgo sampling if conditions are dangerous or inaccessible. These events must be documented and included with records.
4.0 Qualitative Monitoring
Qualitative monitoring schedules have not changed but the following requirements have been modified to include an implementation schedule for corrective actions:
- “Qualitative monitoring shall be conducted at least once every seven calendar days, and within 24 hours after any storm event of greater than 0.5 inches of rain per 24 hour period. During stormy periods, and whenever runoff occurs daily, all stormwater controls shall be inspected daily and immediately before closing operations for the weekends or holidays.”
- “In the event an atypical condition is noted at a stormwater discharge outfall, the permittee shall document the suspected cause of the condition and shall document corrective actions taken in response to the discovery. Uncontrolled releases of mud or muddy water, or visible sedimentation found off site, shall be recorded with a brief explanation as to the measures taken to prevent future releases as well as any sediment clean‐up measures taken.”
- “If the permittee’s qualitative monitoring documentation indicates that existing stormwater controls are ineffective, or that significant stormwater contamination is a recurring condition, the permittee shall investigate potential causes, evaluate the feasibility of corrective actions, and implement feasible corrective actions within 60 days. A written record of the permittee’s investigation, evaluation, and response actions shall be kept on site.”
- “The permittee shall record the required qualitative monitoring observations on the SDO Qualitative Monitoring Report form provided by the Division and shall retain the completed forms on site. Qualitative monitoring results should not be submitted to the Division, except upon DWQ’s specific requirement to do so.”
5.0 Analytical Benchmark Values
Benchmark Values for Analytical Monitoring Requirements
| Discharge Characteristics | Benchmark Value |
| Chemical Oxygen Demand | 120 mg/l |
| Fecal Coliform | 1000 colonies per 100 ml |
| Total Suspended Solids (TSS) | 100 mg/l |
| TSS (ORW, HQW, Trout, and PNA) waters | 50 mg/L |
Benchmark Values for On-Site Vehicle and Equipment Maintenance Activities
| Discharge Characteristics | Benchmark Value |
| pH | Within the range 6.0 ‐ 9.0 |
| Non‐Polar Oil & Grease/TPH [EPA Method 1664 (SGT‐HEM)] | 15 mg/l |
| Total Suspended Solids (TSS) | 100 mg/l |
| TSS (ORW, HQW, Trout, and PNA waters) | 50 mg/L |
6.0 Tier Three Response Actions
The Tier Three response actions that have been added to the draft Permit are summarized below:
“During the term of this permit, if the valid sampling results required for the permit monitoring periods exceed the benchmark value for any specific parameter at any specific outfall on four occasions, the permittee shall notify the DWQ Regional Office Surface Water Supervisor in writing within 30 days of receipt of the fourth analytical results. DWQ may, but is not limited to:
- Require that the permittee revise, increase, or decrease the monitoring frequency for some or all parameters;
- Rescind coverage under the General Permit, and require that the permittee apply for an individual stormwater discharge permit;
- Require the permittee to install structural stormwater controls;
- Require the permittee to implement other stormwater control measures;
- Require the permittee to perform upstream and downstream monitoring to characterize impacts on receiving waters.”
7.0 Duty to Comply (Fines)
The Clean Water Act fines have increased in Part III, Section A, 2 (a) and (f) of the draft permit.
8.0 Closing
Several important changes are being proposed for stormwater monitoring that may impact your landfill operation in the future. Smith Gardner, Inc. would be glad to discuss this draft Permit or other NPDES permits with you if you have any questions.
We would welcome an opportunity to work with you to submit any comments/concerns that you may have to NCDENR-DWQ during the public comment period that ends on October 4, 2012. You may contact Don Misenheimer at (919) 828-0577 x 224 or by email at don@brenta4.sg-host.com.
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