Management Strategies for Copper Sources in Urban Runoff
In 2006, TDC Environmental worked with Larry Walker Associates (and in cooperation with Thomas Barron) to develop management strategies for the primary sources of copper in urban runoff and shoreline activities: architectural copper, vehicle brake pads, copper-containing pesticides, and marine antifouling coatings. The report, which was funded by the San Francisco Bay Clean Estuary Partnership includes the following information:
A menu of available control strategies for each copper source. The pros and cons of each measure are considered. Potential reductions are estimated. Metrics for monitoring control strategy implementation. Both activity and effectiveness metrics are reviewed; the best available metrics are identified. A possible implementation strategy for all measures for each copper source. The strategy indicated preferred and fall-back implementation options and presents time frames that mesh with other strategies.
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Copper Sources in Urban Runoff
In 2004, TDC Environmental completed a comprehensive inventory of the primary sources of copper in urban runoff. The report also identifies sources of direct releases of copper to surface waters from shoreline activities. The report, which was funded by the San Francisco Bay Clean Estuary Partnership includes the following information:
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Copper Sources in Wastewater
During Dr. Moran’s tenure at the Palo Alto Regional Water Quality Control Plant (RWQCP), compliance with tight NPDES permit limits for copper (4.9 ppb) was a challenge. Treatment plant improvements were not an option (the plant provides primary and secondary treatment followed by polishing dual-media filtration), so compliance efforts focused on reducing discharges of copper to the sewer system. Starting in 1994, Dr. Moran began an annual exercise to assemble current copper source identification information and to plan implementation of discharge source reduction programs. This annual exercise was the genesis of the Clean Bay Plan, which Dr. Moran expanded to include all pollutants of concern to the RWQCP. In 1999, Dr. Moran worked with EIP Associates to document the copper source identification work that she had done since 1993.
The report is available from the City of Palo Alto's Internet site:
Copper Reduction Programs
The copper reduction program designed and implemented by Dr. Moran and Palo Alto’s team reduced copper concentrations in wastewater by 49% between 1992 and 1998 (from 87 ppb to 44 ppb). Key components of the program included efforts to reduce copper discharges from:
Since most industrial copper use in the Palo Alto RWQCP service area occurs at metal finishing operations, the industrial portion of the copper source reduction effort focused on metal finishing operations. Dr. Moran participated in the development and implementation of Sewer Use Ordinance requirements specific to metal finishers (and printed circuit board manufacturers, which use metal finishing techniques). The program involves a relatively unusual regulatory approach that integrates pollution prevention into regulatory requirements. Pollution prevention studies conducted by the RWQCP and by other agencies were used as the basis for development of a set of pollution prevention measures, called "Reasonable Control Measures," (RCMs) that Palo Alto considers to be minimum standards for metal finishing operations. Each of the measures is widely applicable, generally feasible for all operations, has a simple payback period of five years or less, and meets safety and product quality criteria.
Metal finishers that use copper were required to select one of two options for compliance. The first option, known as the “RCM Option,” involves installation of the Reasonable Control Measures, and meeting an annual average copper concentration limit of 0.4 mg/l of copper in the facility wastewater discharge. The second option, called the “Mass Limit Option,” involves performing a RWQCP-conducted pollution prevention study, and using the study to set a facility-specific annual copper discharge mass limit consistent with implementing identified pollution prevention measures that have a payback period of five years or less. Between adoption of the ordinance (1995) and 1998, the program achieved a 42% reduction in metal finishing copper discharges.
Investigations conducted by the RWQCP determined that cooling water systems were a significant source of water pollutants, especially copper and tributyltin. In response, the RWQCP team developed and implemented an action plan to reduce copper and tributyltin discharges from cooling systems. First, RWQCP staff created a brochure of best management practices for cooling water system operation. Then, the team distributed the brochure to facilities managers at all identified buildings with cooling systems and provided cooling system product vendors and other interested parties with copies of the brochure and information about problem additives (those containing copper and tributyltin). Dr. Moran and discussed the issues directly with numerous facilities managers and product vendors to educate them on the issue and convince them that changing to the recommended procedures would extend system lifetimes without increasing cost, while helping remedy the environmental problem. Dr. Moran also trained inspectors to ensure this issue was addressed effectively during each inspection.
Both conversations with facilities managers and inspection results showed that the use of copper and tributyltin-containing cooling water additives was a significant problem—and a problem that could not be solved by education alone, given the complexity of the additive market (just remembering the word tributyltin is difficult for most people). On the basis of this finding, the Dr. Moran led successful efforts to have the California Department of Pesticide Regulation ban the sale and use of tributyltin cooling water additives in late 1995.
These efforts have reduced discharges of copper and tributyltin to the RWQCP. For copper, the RWQCP saw a 25 percent reduction in discharge concentrations from cooling towers between the program’s implementation in 1995 and 1998 (concentrations fell from 0.34 mg/l to 0.26 mg/l). RWQCP effluent has not exceeded its tributyltin effluent limitation since 1995.
Vehicle Service Facilities and Car Washes
Dr. Moran participated in a highly effective program to reduce discharges of copper and other pollutants from vehicle service facilities. Historically, vehicle service facilities, such as auto repair shops, gasoline stations, fleet maintenance facilities, commercial car washes, and autobody repair shops, have discharged pollutants to both sewers and storm drains. Major tasks each year include:
Between the inception of the program in 1994 and 1998, the portion of eligible facilities recognized as Clean Bay Businesses increased from 49% to 94%. Of the 305 vehicle service facilities regulated by the RWQCP in 1998, 247 chose to be zero dischargers (no discharge to the sanitary sewer or storm drain) and about 58 facilities were permitted to treat their wastewater and discharge it to the sanitary sewer.
Some root control products intended for discharge to the sewer contain as much as 25% copper. In 1992, all cities in the RWQCP service area prohibited the discharge of copper-based root control products to the sewer system. Unfortunately, the RWQCP lacked legal authority to ban the sale of the root control products and could not prevent purchase and use of products from large regional stores in neighboring towns. Since the root killer was a significant source of copper in wastewater, the Dr. Moran pursued several efforts to strengthen the local prohibition. Legislation sponsored by the RWQCP and carried by Assembly Member Byron Sher prompted the California Department of Pesticide Regulation to adopt regulations prohibiting the sale and use of copper-based root control products in the nine Bay Area counties on December 11, 1995.
Data from residential wastewater trunk line sampling show nearly a 25% reduction in copper levels in 1996 and 1997 as compared to 1995. While other activities may have contributed to this reduction, the primary cause is probably the sales ban on copper-based root-control products. Given the RWQCP’s prior efforts to eliminate the use of this product, the magnitude of this reduction is somewhat surprising; however, it highlights the impact of the large regional stores outside the RWQCP service area on local pesticide use.
Corrosion of Copper Piping
Approximately 58% of the copper discharged from the RWQCP comes from corrosion of copper pipes in homes and businesses. During 1995, Dr. Moran managed an investigation of copper piping corrosion and potential corrosion reduction measures. The study, which was conducted by Dr. Moran and a consultant in coordination with City of Palo Alto Planning and Utilities Department staff and the City of San Jose, involved the following tasks:
Vehicle Brake Pads
Available data suggest that brake pads are the major source of copper in urban storm water runoff. Each year, urban runoff releases significantly more copper to South San Francisco Bay than do wastewater treatment plants. By addressing copper releases from vehicle brake pads, Dr. Moran’s strategy was to try to identify a solution to the copper water quality problem. Solving the problem would eliminate the need for additional, costly reductions in already low copper discharges from wastewater treatment plants. Working with the San Francisco Estuary Project and Common Ground for the Environment (a joint project of Stanford University and the non-profit organization Sustainable Conservation), Dr. Moran initiated development of the Brake Pad Partnership, a national work group including all major vehicle brake manufacturers, government agencies, and environmental groups. Once participants learned that elevated copper levels have been listed as a cause of impairment for many rivers and estuaries in the United States, group members pushed for actions to address the brake pad contribution to the problem. Dr. Moran provided motivation and technical support (regarding sources of copper in urban runoff and control measure cost and effectiveness) for the work group. In May 1999 brake manufacturers promised to conduct additional cooperative research on the environmental impacts of vehicle brakes, and to reformulate products to reduce brake-related copper problems in rivers and estuaries and to prevent future environmental problems from brakes.