Petroleum facility treats storm water runoff with pressurized & adsorptive media filtration
Achieving storm water regulatory compliance at industrial facilities sometimes can be a daunting task. Maxum Petroleum’s diesel fueling and petroleum fuel and lubricant shipping and receiving facility, located on Harbor Island, Wash., in the Puget Sound, experienced many storm water challenges; however, it was successful in reaching compliance after implementing a systematic approach with targeted strategies. The Maxum Petroleum facility includes a parking and driving area used for truck parking and loading and unloading products; a warehouse and tank farm; and a 590-ft long pier (Pier 15), which is utilized for receiving and shipping petroleum fuels and lubricants, and the operation of a diesel fueling station for the commercial marine trade.
In the state of Washington, storm water runoff from industrial sites is regulated under the State of Washington Department of Ecology (Ecology) Industrial Stormwater General Permit (ISGP), which has established some of the toughest water quality standards in the country. ISGP water quality benchmarks include copper at 14 mcg/L and zinc at 117 mcg/L. Achieving these low benchmarks presents a challenge for many facilities, and during recent years, many facilities have triggered an ISGP Level 3 Corrective Action due to benchmark exceedances.
Implementing a Level 3 Corrective Action includes development of an engineering report that must be approved by Ecology, as well as installation of appropriate treatment best management practices (BMPs) with a goal of meeting benchmark requirements. The consequences of ISGP non-compliance can introduce significant uncertainty to business operations, including the possibility of large capital investment, ongoing operation and maintenance costs associated with treatment systems, and third-party enforcement of the Clean Water Act (CWA) through citizen suits, which continue to be more active in Washington than any other state.
Storm water monitoring results at Maxum Petroleum’s facility indicated that copper exceeded the ISGP benchmark value during three quarters of 2015. The facility was required to prepare an engineering report describing proposed Level 3 Treatment BMPs for the site, with the treatment system needing to be constructed and operational by Sept. 30, 2016.
Meeting the deadline required the identification and installation of a storm water treatment system for achieving cost-effective, long-term compliance with ISGP requirements. The approach and strategies used to complete this project included:
- Screening potential treatment technologies;
- Conducting laboratory bench-scale testing on the most promising technologies to validate performance and to confirm and finalize the preferred treatment approach;
- Preparing an engineering report documenting results and providing details of the proposed full-scale treatment system; and
- Implementing required storm water infrastructure modifications and installing the treatment system.
The treatment system met all ISGP water quality benchmarks.
A variety of water quality treatment technologies initially were considered for the facility. Space constraints were a factor in evaluating the storm water treatment alternatives, as the area available for locating a water quality treatment system was limited due to the presence of a large warehouse building, tank farm, designated driving pathways, work areas and fence lines. To help evaluate the effectiveness of potential treatment technologies, treatability testing was performed using site storm water.
Clear Creek Systems Inc. (CCS) of Pacific, Wash., performed bench-scale treatability testing. The testing used a 15-gal sample of storm water collected from the outlet chamber of the oil and water separator connected to the single catch basin at the facility. CCS’s bench-scale treatability testing evaluated the pressurized filtration, adsorptive media and ion exchange treatment train.
The treatment technology testing using the pressurized filtration and adsorptive media filtration demonstrated excellent results for achieving applicable ISGP water quality benchmarks, as total copper (less than 0.2 mcg/L) and total zinc (less than 0.5 mcg/L) were reduced to nondetection levels. Because metals were at nondetectable levels prior to the ion exchange media, no further reductions were achieved. The pressurized filtration and adsorptive media filtration system, with gravity settling included at the start of the treatment train, was selected as the preferred technology for treating storm water runoff at Maxum Petroleum’s facility.
The only change in the storm water capture involved redirecting runoff from the warehouse roof. The roof runoff, which originally was conveyed to Elliott Bay via two outfalls located in the shoreline seawall adjacent to Pier 15, was re-plumbed and directed to pavement and the one existing catch basin at the facility. This drainage modification resulted in a treatment drainage area of 0.86 acre. A new manhole and pump station were installed in the storm water drainage line that routes storm water from the existing catch basin and oil and water separator to the outfall located under Pier 15. Storm water is pumped from the manhole and routed to the treatment system through an influent pipe, and treated effluent is returned to the downstream side of the manhole through a parallel effluent pipe.
The treatment process can be summed up as gravity settling to pressurized filtration to adsorptive media. The treatment system CCS designed and fabricated includes:
- Submersible pump with panel and auto-start controls;
- 2,000-gal poly water storage tank with bulkhead fittings and valves;
- High-pressure filtration system pump with panel and auto-start controls;
- Filtration skid containing a bag filter housing and a cartridge filter housing plumbed in series;
- Filtration skid containing two 25-cu ft adsorptive media vessels with interconnecting plumbing;
- Interconnecting plumbing; and
- Integral mount totalizing discharge flowmeter.
The installation goal was achieved for the treatment system and the water quality monitoring results for the fourth quarter of 2016 through the first quarter of 2018 indicated that all ISGP water quality benchmarks were easily achieved, as copper averaged 2 mcg/L, zinc averaged 11 mcg/L, and turbidity averaged 1.4 NTU.