Dennis Dembiec, P.E., Director of Engineering and Public Services, City of Birmingham, Michigan
Kenneth Eyre, P.E., Associate, Greeley and Hansen LLC, Norfolk, Virginia
Recognizing that operations and maintenance (O&M) of our nationâ€™s water, wastewater and storm sewer infrastructure is regulated by federal and state agencies, the U.S. Environmental Protection Agency (EPA) established in 1998 a program to verify technologies that protect ground and surface water from contamination. The program is known as the Water Quality Protection Center (WQPC) and consolidates the Wet Weather Flows (WWF) Pilot Program with the Source Water Protection category. The purpose of the program is to evaluate commercial-ready technologies from U.S. and foreign manufacturers and suppliers. The EPA asked stakeholder advisory groups to participate with the WWF Pilot Program, and APWA is one of the stakeholders that has participated from the inception, along with the CSO Partnership. The U.S. Congress mandated that the WWF Pilot Program be phased out in May 2003. Consideration is being given by APWA to continue with the new Water Quality Protection Center in an advisory capacity.
Primarily the Environmental Technology Verification (ETV) programâ€™s purpose is to encourage the verification of readily available technologies, solely on the merits claimed by the manufacturer. The decision to subject a device or process to this third-party evaluation is strictly voluntary. Preparation and submission of rigorous testing protocols is funded by the vendor/provider, and is reviewed by experts retained under contract to the EPA. NSF International is the independent not-for-profit organization charged with representing the interests of the ETV WWF stakeholders. NSF International is located in Ann Arbor, MI. For additional ETV WWF information contact John Schenk at (734) 913-5786 or by e-mail at firstname.lastname@example.org.
At the latest ETV WWF briefings, there were numerous presentations on some of the newer stormwater devices and systems. The purpose of this article is to disseminate information from programs such as the ETV, and to present some of the application information and technical details associated with the in-ground stormwater treatment installations.
In case you are not familiar with the ETV WWF process, the EPA continuously reinforces that this process:
DISCLAIMER: The references to individual manufacturers and suppliers do not reflect an endorsement by APWA, the EPA or the authors. The information provided is for technical purposes only. Each technology should be evaluated for each specific application.
Basic components consist of a series of flow regulated filter cartridges contained within an 8-ft by 10-ft vault. The hydraulic operation relies on a float mechanism to control the batch dosing. The hood covering the in-ground unit is vented to allow for the siphonic discharge. The siphonic release provides for uniform hydraulic distribution across the filter. The cation exchange capacity of the filter media is suitable for metals removal from the flow. Petroleum-based oil and grease removal is another feature of this technology as the filter media has absorption capability. The hydraulic rating for the Griffin, GA application is 10 cubic feet per second. The Wisconsin Department of Natural Resources (WDNR) also has a test installation of this system in Milwaukee.
BaySaver Solids Removal Unit
This treatment method is an in-line system that utilizes the variance between the specific gravity of particles to promote separation. This device lends itself to removing floating sediments and contaminants, including petroleum-based hydrocarbon compounds. There are two chambers to the system; the first chamber is the primary inlet where gross solids are collected. A separator between the primary chamber and secondary chamber serves to regulate the flow. The secondary chamber provides storage after treatment. The collected contaminants are retained in the system until removed during routine maintenance visits.
Arkal Filtrations System
This technology is an adaptation from the site irrigation industry and has been installed at a hospital in Green Bay, WI. The drainage area is six acres with surface features characterized as impervious parking lot and rooftop. The system is a pressurized filter system, which allows for downsizing the storage system. Specific operational issues, which challenged the team monitoring the performance of the system, included the capture of representative samples from the storm flow. Use of an adjoining storm sewer helped with the sampling access when a backflow prevention mechanism was retrofitted into the configuration, to accommodate the systemsâ€™ overflow. Another challenge, due to the intermittent nature of storms and their duration and intensity, was the discovery of a buildup of bacteria in the pre-filters. The project team is presently addressing these issues during the shakedown phase.
As part of the Wisconsin Department of Natural Resources (WDNR) stormwater control regulations, the Wisconsin Department of Transportation (WDOT) will have to reduce solids laden runoff from their facilities by 40 percent. The WDOT, WDNR, USGS, City of Milwaukee, Milwaukee County, and numerous engineering firms have partnered for a test site below an elevated highway along the riverfront area in downtown Milwaukee, where this system has been installed. The elevated roadway drainage area is approximately 0.2 acres and has an average daily traffic rating of 40,000 vehicles per day.
Specific issues that the team has to deal with include control of the storm runoff velocities from the elevated roadway prior to entry into the system. Other issues include characterizing the roadway abrasion material anticipated to be carried with the storm runoff from the elevated highway. The team also faced the challenge of installing the systems in a very small area. The selected area under the freeway was in a parking lot, so the project team had to negotiate trading off valuable parking sites with the local agencies in order to accommodate the installations.
It should be noted that other agencies have evaluated some of the technologies in the EPA ETV program and the results of these independent assessments can be found through the Internet or by contacting State DOTs and other regional jurisdictions (too numerous to list!).
Benefits of the verified stormwater technologies to public works activities: