Copper

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.

Download the report:

Copper Management Strategies Development Resources, 2006

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:

• Provides estimates of the amount of copper released to San Francisco Bay from each source;
• Estimates the relative degree of uncertainty in each copper release estimate and lists the sources of uncertainty for each estimate;
• Reviews available control measures for each copper source, providing control measure effectiveness information to the extent data are available;
• Identifies feasible control measures for copper sources in urban runoff and shoreline activities; and
• Identifies priorities for investigation of sources and control measures.

Download the report:

• Copper Sources in Urban Runoff and Shoreline Activities, 2004

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 Source Identification Report, 1999

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:

• Printed Circuit Board Manufacturers and Metal Finishers
• Cooling Water Systems
• Vehicle Service Facilities and Car Washes
• Copper-Based Root Control Products
• Corrosion of Copper Piping
• Vehicle Brake Pads

 
Printed Circuit Board Manufacturers and Metal Finishers

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.

Cooling Water Systems

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:

• Visiting every facility at least once.  The primary purpose of the visit is education and interaction with facility operators to increase compliance rates. During visits, facilities are evaluated for compliance with ordinance requirements.
• Recognizing compliant facilities as Clean Bay Businesses.  Clean Bay Businesses receive a window sticker and are listed in full-page newspaper advertisements paid for by the RWQCP.
• Enforcing requirements.

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:

• Revising the estimate of annual corrosion-based copper load to RWQCP, using lead and copper rule test data and new corrosion testing performed by the contractor.  The copper source identification work utilized the revised corrosion load estimate.
• Developing a strategy (including plans and costs) for local addition of a corrosion inhibitor to Palo Alto's drinking water.  The study, which included preliminary design plans for inhibitor addition systems, was created to facilitate a decision by the City as to feasibility, desirability, economics, and environmental benefits of local inhibitor addition.  The study concluded that addition of 1 milligram per liter (mg/l) orthophosphate to control corrosion in Palo Alto’s water supply would be technically feasible and potentially be a cost-effective method of reducing discharges of copper to the RWQCP.  On the basis of this study, the City of Palo Alto decided to make corrosion inhibitor addition its primary contingency strategy for achieving compliance with copper discharge requirements.
• Obtaining information about locations and copper discharges from cooling towers, recirculating hot water systems, and heating systems; estimating the annual copper loading to the RWQCP from these sources.  These load estimates were incorporated into the copper source identification study.
• Evaluating material substitution, system design, and installation Best Management Practices as means to reduce copper discharge due to corrosion of copper piping.  The study made specific recommendations for design, installation, and operation of cooling water systems, operation of recirculating hot water systems, and installation of copper and non-copper potable water piping.  Most recommended practices would extend piping system lifetimes without a significant increase in the cost of system installation or operation.  Working with the San Jose and Sunnyvale Water Pollution Control Plants, the Dr. Moran developed a set of best management practices for plumbing installation, which the three plants jointly converted into a booklet for distribution to plumbers.  Using the report’s recommendations, Dr. Moran also drafted best management practices for facilities managers and building designers, which the RWQCP plans to convert into a brochure for distribution during building plan review and at facility inspections.

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.

• Current information on the Brake Pad Partnership is available on the Partnership's Internet site.