Source Control Enhancements to Foster Indirect Potable Reuse

Source control programs have historically been developed to control toxic pollutants from industrial facilities to address issues related to meeting ocean discharge requirements, preventing harm to physical facilities and the biological treatment processes within treatment plants, minimizing hazards to workers, and protecting aquatic resources in the river or ocean where discharges occur. With increasing water demands and the need for larger amounts of water recycling, source control programs need to be expanded to also control pollutants of concern from drinking water perspective in order to account for the reuse of treated wastewater. Reuse of treated wastewater through injection or surface spreading can supplement groundwater supplies and may impact the quality of groundwater used for drinking water. This factor needs to be considered when determining the objectives of source control programs and the strategy to achieve the source control objectives.Source control enhancements need to go beyond the requirements in the Clean Water Act and federal pretreatment program regulations defined in 40 CFR, Part 403, to actively address compounds that pose a risk to drinking water quality in areas where indirect potable reuse occurs or is planned. The Orange County Sanitation District and Orange County Water District are implementing a 70 million gallon per day indirect potable reuse project. As part of this project, we are evaluating enhanced source control activities, including:Developing a list of target compounds of concern based on drinking water regulationsAssessing the fate of the target compounds through the treatment system.Focused monitoring based on the list of target compounds and their potential ability to persist through the treatment system.Characterizing wastewater streams to identify the sources and levels of pollutants of concerns in an effort to minimize these pollutants.Increased outreach to dischargers to manage discharge of compounds of concern at the source.Maintaining an inventory of compounds discharged into the wastewater collection system so that new compounds of concern can be evaluated rapidly.Although mechanisms are currently in place to control the majority of the pollutants to the desirable levels, challenges arise while pursuing these activities, including:Avoidance of one region having stricter source control requirements compared to other areas, which would place industry in the stricter source control area at a disadvantage.EPA-approved analytical methods may be required for legal enforcement of source control regulations, and some constituents of concern do not have EPA-approved analytical methods, or the EPA-approved method does not have a sufficiently low detection limit.Discharge limits for some constituents, such as radionuclides, are set through federal requirements which are not flexible, and changing the requirements is an arduous process.Developing authorities and mechanisms to control pharmaceuticals and personal care products that may be constituents of concern is a new field.The Orange County Sanitation District and Orange County Water District are addressing these challenges in collaboration with the regulatory agencies by developing policies and standards to implement an enhanced source control program.