Plastics in Industrial Stormwater Runoff – More than just Nurdles

A “nurdle” is a plastic pellet that is melted and molded to create plastic products.  Facilities that handle, transport, or manufacture nurdles or “pre-production plastics” (defined as “plastic resin pellets and powder coloring for plastics”[1]) are now required to implement best management practices (“BMPs”) to control discharges of the plastics from their facility. [2]

By state law, the State Water Resources Control Board (“SWRCB”) and the Regional Water Quality Control Boards (“Water Board”) are required to address discharge of pre-production plastics.  One way in which these state programs address these discharges is through regulation of runoff from industrial facilities.

Industrial Stormwater General Permit Requirements

In accordance with Assembly Bill 258 (Krekorian), the SWRCB included in the General Permit for Storm Water Discharges Associated with Industrial Activities (Order 2014-0057-DWQ; “General Permit”), effective July 1, 2015, specific requirements for facilities that handle “Plastic Materials.”  These requirements include implementing stormwater runoff containment systems to capture plastic particles before they leave a facility. [3]  However, in the General Permit, the SWRCB defined Plastic Materials as:

“… virgin and recycled plastic resin pellets, powders, flakes, powdered additives, regrind, dust, and other similar types of preproduction plastics with the potential to discharge or migrate off-site.”


ˆPlastic Shredding Machine

The General Permit definition of Plastic Materials is much more expansive than the legislative requirements, which is limited to “pre-production plastics.”  Given this more expansive definition in the General Permit, identification of those facilities that do and don’t qualify as “Plastic Facilities” is much more difficult.  In certain cases, preventing accidental discharge of a plastic may be a simple matter of implementing additional good housekeeping BMPs.  In other cases, a discharge of plastic could qualify as a discharge of an “other similar type of pre-production plastic” and be a violation of the General Permit and consequently the Clean Water Act.

AB 258 also requires these Plastic Facilities to implement a containment system at each on-site storm drain discharge location down gradient of areas containing plastic material.  These containment systems must be designed to trap all particles retained by a 1-mm mesh screen with a treatment capacity of the peak flow rate generated by a one-year, one-hour storm.

However, the General Permit states:

“Plastics Facilities that handle Plastic Materials smaller than 1 mm in size shall develop a containment system designed to trap the smallest plastic material handled at the facility with a treatment capacity of at least the peak flow rate from a one-year, one-hour storm…”[4]

Therefore, Plastic Facilities must analyze and capture the smallest particle size at the facility, which could be much smaller than the 1-mm size threshold identified in the legislation.  More specifically, the General Permit requires Plastic Facilities to implement:

  • A “containment system” at each on-site storm drain discharge location down gradient of areas containing plastic material…with a treatment capacity of the peak flow rate generated by a 1-year, 1-hour storm;
  • An alternative, functionally equivalent system capable of capturing or achieving the same or better performance standard…with a treatment capacity of the peak flow rate generated by a one-year, one-hour storm; or
  • Alternative, functionally equivalent systems that must be submitted to the RWQCB for prior approval.

Other mechanisms for compliance with the General Permit that do not involve containment are (1) if a Plastic Facility meets the “no exposure” requirements of the General Permit[5] or (2) have implemented eight separate BMPs.[6]  These eight separate BMPs include:

  1. Training programs,
  2. Maintenance programs,
  3. Waste management programs,
  4. Proper operation and maintenance of outdoor conveyance systems,
  5. Use of durable, permanent structures that prevents exposure of outdoor Plastic Materials to weather,
  6. Scheduling regular housekeeping and routine inspections,
  7. Spill response and prevention procedures, and
  8. Correction of any deficiencies in these BMPs that may result in errant Plastic Materials discharged.

However, any discharge or off-site migration of Plastic Materials constitutes an illicit discharge and is a direct violation of the General Permit.

Stormwater Containment Systems

In California the amount of rainfall from the 1-year, 1-hour precipitation event generally ranges between 0.1 and 1 inch.  For sites with mostly impervious surfacecatchbasininsertss, such storms result in flow rates of approximately 10 to 100 gallons per minute per acre.  So, depending upon the facility size and location, the containment system sizes could vary significantly.

However, Plastic Facilities that must implement containment systems have a range of options available.  Many systems capable of handling the design flow rates are available, but careful analysis of plastic sources, particle size, and treatment removal effectiveness is needed to properly design such a system.  The majority of trash capture BMPs, such as catch basin inserts, are not designed to capture resin pellets and smaller particles.  Some media filters will likely be able to remove large particles, but usually require pumping of stormwater, which may not always be practicable for a facility’s given configuration.

Plastic Facilities should carefully evaluate any containment system intended to meet the General Permit requirements to ensure it will meet the rigorous performance standards of the General Permit.  Also, unlike other pollutants of concern in stormwater, many plastics are plainly visible to the naked eye making it much easier to prove that a discharge occurred.

Citizen Lawsuits under the Clean Water Act

The Clean Water Act contains provisions that allow environmental groups and private citizens the right to file lawsuits, after the 60-day notice period, against businesses if regulatory agencies have failed to enforce provisions of the Clean Water Act.[7]  Here, environmental groups have three distinct advantages: (1) decades of experience in Clean Water Act litigation and (2) the high cost of litigation, and (3) they have the right to recover the costs for their efforts.  Settlements or judgement in plaintiff’s favor typically result in the full costs of litigation being borne by the defendant.  Additionally, these types of lawsuits also result in defendants spending substantial time and money on structural and operational improvements to their stormwater management program.

A number of environmental groups (e.g., Plastic Pollution Coalition) are targeting plastic material facilities and have recently filed lawsuits under the Clean Water Act.  Although the new General Permit is now in effect, there is a 5-year statute of limitations on compliance-related matters.  Therefore, these lawsuits can allege non-compliance under the old 1997 General Permit as well as deficiencies associated with complying with the new General Permit.

Implementation Strategies

Plastic Facilities may want to consider an iterative approach to compliance with the General Permit.  This iterative approach could consist of first implementing the eight BMPs identified in the General Permit before committing to potentially more expensive stormwater containment systems.  During the implementation of the eight BMPs, a Plastic Facility can conduct a monitoring program evaluating the BMP effectiveness.  At the same time, a Plastic Facility can evaluate containment system alternatives, potentially including conceptual designs and cost estimates, to make informed decisions about continued compliance with the General Permit.

Given the potential liabilities associated with citizen suits under the Clean Water Act, it is imperative that facilities handling Plastic Materials ensure they are properly complying with the current General Permit.  Due to the 5-year statute of limitations, Plastic Facilities may want to evaluate potential compliance issues that may have occurred under the 1997 General Permit.

For more information on the requirements of the General Permit for plastic materials facilities, please contact Matthew Zucca, P.E., QISP/ToR at (650) 292-9100.

[1] California Water Code (“CWC”) §13367

[2] AB 258, Krekorian; California Water Code (“CWC”) §13367

[3] BMPs were derived from ACS, 2015. Operation Clean Sweep. American Chemistry Council, dated 2015 and USEPA, 1993.Plastic Pellets in the Aquatic Environment: Sources and Recommendations. United States Environmental Protection Agency. EPA/842-S-93-001. August 1993

[4] General Permit Section XIII(a)(1)(f)

[5] General Permit Sections XVII and XVIII.A.2.a

[6] General Permit Section XVIII.A.2.b

[7] 33 United States Code 1365, Section 505