When source controls are not enough: Considering advanced urban runoff treatment

James B. Rasmus, P.E., DEE
Program Manager
PBS&J
Encinitas, California

While growing up in Southern California, beach postings and closures were not typically headline news. Today, postings and closures are commonly seen in daily newspapers. General warnings about water quality are now key features on the nightly news. Watchdog groups have entire websites dedicated to exposing water quality problems at popular locations.

Public works managers and those in the stormwater industry throughout the nation have long been aware of the looming deadlines for NPDES compliance and the penalties associated with non-compliance. This has led to a new level of importance being placed on source controls and Best Management Practices (BMPs). This is a good thing; however, the level of treatment for bodies of water where there is a high degree of public contact may require even higher levels of treatment. Of course, public education, source controls and watershed planning are the long-term answers to a healthy watershed, but these measures take time (often generations) to take effect. The public works world needs to stand back and consider the economics of more advanced levels of treatment now in locations where the long-term solution is not pragmatic.

Things to consider
Recent changes in monitoring, reporting, postings, and closures of beaches and other water bodies have resulted in a new level of public awareness and scrutiny. Since 1999, in California, Assembly Bill 411 has required increased bacteriological testing and monitoring of water bodies that have a high degree of public contact. Other states have similar requirements for recreational waters. Several agencies such as the Cityies of Santa Monica, Malibu, Dana Point, Encinitas and others are already implementing advanced levels of treatment at "end of the pipe" locations where public contact is high and tourism dollars are at stake. Typically, these agencies already have successful source control programs in place and they have supplemented these measures with advanced treatment in areas that have high recreational use.

In addition to direct contact applications there are plenty of applications such as fishery enhancement, eco-tourism, wetlands, agriculture, and other sectors that can immediately benefit from more advanced forms of runoff treatment.

The burgeoning BMP marketplace has resulted in recent advances in the removal of coarse debris, oils and grease, suspended solids removal, and sediment from runoff. When these processes are combined with commercially available filtration, ultraviolet light, and ozonation systems, the result can be a cost-effective application for advanced treatment of urban runoff.

How should APWA proceed?
There is no single best response on where to implement advanced forms of treatment of urban runoff. Initial candidates for advanced treatment of urban runoff can be determined from a review of posted locations or areas with a history of urban water quality issues. From this list of candidates, one needs to focus on those locations where there would be significant public (and thereby economic) benefits.

When a suitable project is selected for implementing more advanced forms of treatment for urban runoff, the following ideas may offer some guidance and assistance for implementing these types of systems:

  • Throughout the design, involve staff members who are responsible for stormwater facilities, as well as those who are responsible for sanitary facilities—each group has a lot to offer.

  • Assess water quality carefully, including bacteriological contamination as well as constituents that may impact process selection. Such criteria may include iron, manganese, turbidity, TSS, TOC, and others.

  • Generally, redundancy is not as important for these types of facilities when compared to traditional water and wastewater treatment plants. With this in mind, costs may be reduced, thereby making such systems more feasible and cost effective for your agency.

  • Finally, consider incorporating public education, monitoring, and research facilities into these projects. There is a lot of public support and appreciation for these types of projects, so it may be helpful to demonstrate the ongoing benefits and results to the public. Also, a permanent, protected facility with monitoring capabilities lends itself well to long-term monitoring and research of water quality.
Now that many states and communities are placing a high level of importance on recreational waters, public works must look for opportunities to cost- effectively utilize available technologies to provide safer waters.

James B. Rasmus can be reached at (760) 753-1120 or at jbrasmus@pbsj.com.