2017 CASQA Award Winner - Outstanding Industrial Stormwater BMP Project: West Hylebos Pier Log Yard
In 2010, to comply with Washington state’s tough Industrial Stormwater General Permit (ISGP) stormwater requirements, the Port of Tacoma (Port) faced the choice of coming up with cost-effective treatment for its West Hylebos Log Yard or shutting down the line of business that supports 40 direct jobs at the Port and hundreds of jobs in logging, trucking and associated services. The Port and Kennedy/Jenks Consultants (Kennedy/Jenks) considered a range of runoff treatment approaches, and the aggregate results of the comprehensive evaluation indicated that a biofiltration treatment system (system) would most effectively manage stormwater discharges from 25 acres of paved logyard and best achieve the combined project goals. The Port chose to design (actually invent) and build a $2.7 million treatment facility. The treatment system reduced pollutant loads by 92% right out of the blocks and continues to improve over time.
Biofiltration is an innovative approach for stormwater treatment at industrial facilities. It has traditionally been applied for flow-control in the urban environment. Since biofiltration is a relatively new stormwater treatment technology, its effectiveness was unknown at the time of project development. For this reason, the Port performed multiple rounds of pilot studies to evaluate pollutant removal efficiency and hydraulic performance of adsorptive filtration medias. In order for biofiltration to be successful in this scenario, the system had to process runoff quickly through the system to keep the footprint within reason and also meet water quality goals.
Prior to preparing construction plans and specifications, the Port prepared a preliminary design based on the results of the pilot studies, and worked closely with the Washington State Department of Ecology (Ecology) to gain their approval of the proposed treatment approach. The Port and Kennedy/Jenks ultimately developed a four-stage system implementing two preliminary filtration cells applying inert and adsorptive media, followed by two vegetated biofiltration cells. Each stage has pollutant-specific targets and underdrains to collect filtered stormwater. In order to convey stormwater flows through the system, lift stations are installed at specific locations based on system elevations.
The Biofiltration system at the West Hylebos Log Yard has achieved significant reduction of the project priority pollutants of concern and increased the environmental quality at the log debarking, sorting, and exporting facility and of Commencement Bay. Since implementation in December 2013, all project parameters (including pH, turbidity, zinc, copper, TSS, and COD) have achieved consistent attainment status, qualifying for reduced sampling under the ISGP. Currently, ISGP benchmarks for turbidity, total zinc, total copper, TSS, and COD are equal to or more stringent than the California Industrial General Permit (IGP) Numeric Action Levels (NALs). The treatment BMP does not impact tenant operations and has proven to be very easy to maintain, with minimal cost.
The technologies and ideas used in the design of the system were implemented with the realization that stormwater requirements are going to become more restrictive over time. As such, alternatives to sanitary sewers and advance treatment systems that rely on mechanical filtration and chemical treatment are needed. Designing a treatment system that met the requirements of the particular port industry, was able to achieve ISGP benchmarks, had a variable treatment capability, and met operational size restrictions based on land available was essential. These design restraints will apply to thousands of facilities, including those operated by ports, municipalities, and varied other industries. The pilot study approach and easily sourced materials used for the biofiltration stormwater treatment facility can easily be adapted to meet the needs of the maritime industry and many oth
Ross Dunning is Kennedy/Jenks Consultants' company-wide storm water practice leader located in Federal Way, WA. Ross is a licensed civil engineer with extensive experience in the fields of industrial stormwater management and permit compliance including source control, conveyance, and treatment evaluation and design. Ross is a recognized leader in the stormwater regulatory arena with a long history as an advocate for ports and business. He has assisted dozens of industrial clients including most of the Northwest Ports, Boeing, BNSF, and many others to develop stormwater management and pollutant source control and treatment strategies to address the ever tightening NPDES Industrial Storm water Permit regulations.