Summary

EPA is issuing a notice of proposed action under the Clean Water Act to issue a modification to the National Pollutant Discharge Elimination System (NPDES) permit GU0020397 to: Cabras marine Corporation 178 Industrial Ave. Piti, Guam, 96915.

The Permittee operates and discharges from the floating dry dock located in the Apra Harbor Complex in the Territory of Guam. The AFDL-21 dry dock is located at the facility to primarily provide ship repair and maintenance services to small vessels; e.g., tug boats, personnel support boats, government owned vessels and barges. Typical industrial activities that occur on the dry dock include, but are not limited to, abrasive blasting, pressure washing, application and removal of marine surface coat materials, hydrostatic testing, metal work, electrical work, mechanical work, and material storage.

The proposed permit modification describes that stormwater collected on the dry dock deck and pumped on shore will be directed through a rainwater filtration system for treatment and removal of particulate matter and oily substances. This new rainwater filtration system is comprised of a 2000-gallon storage tank followed by an oil-water separator and several sequential filters to remove particulate matter down to the 100-micron pore size. This treated water will then be discharged to Apra Harbor at a new outfall-013; this new outfall is located next to the floating drydock.