Portable Passive Precipitation Filter. Blending economic vitality with environmental sense URS. Marisco Ltd.

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1 Portable Passive Precipitation Filter Blending economic vitality with environmental sense Marisco Ltd. URS

2 Marisco, Ltd. is Hawaii s largest privately owned shipyard and drydock facility. Located in Kapolei on the West side of the island of Oahu in Hawaii, it employs up to 125 personnel during peak production cycles accomplishing related tasks both at its Kapolei facility and for the Government at Pearl Harbor. An EPA compliance audit of the company in 2008 resulted in concerns mostly of an administrative nature that were easily resolved. More complicated, however, were EPA allegations surrounding reported levels of constituents of concern, most notably those of Copper and Zinc often found in anti foulant systems, in Marisco s drydock effluent resulting from hull preservation activities. URS was hired as a consultant to assist in a study involving an alternative sampling and analysis plan and to determine if there was a better method for dealing with the drydock effluent and its copper and zinc levels.

3 URS and Marisco decided to pursue a closed loop retention system for drydock wash down with fresh water and treatment and re use of that water for future drydock events. URS and Marisco s environmental staff researched many different existing technologies concluding none would treat residual wash water sufficiently to bring levels of inorganics down below NPDES standards. It was realized a new filtration system would have to be pioneered to meet our needs. The ensuing design, called the 3PF System, or Portable Passive Precipitation Filter system, has proven enormously successful in table top model testing in remediating nearly all Copper and Zinc from deck wash water ranging at the highest concentrations from 170,000 to 280,000 µg/l over a designated treatment time brought down to an ND level in analysis.

4 In general, the overall flow path for the filtration treatment systems is as follows: The dry dock platform tilts and is maneuverable to a particular discharge point. The discharge point will drain waters into a collection basin (sump). Gravity flow or mechanical pumping will carry the collected waters to the portable treatment system which is intended to have a 3,750+ gallon capacity (about three wash waters volume in a cycle) which will allow retention time for treatment. Upon treatment, waters then will be passed to a storage tank of at least 5000 gallon capacity to store said treated waters for future use in another dry dock wash water cycle.

5 Shipyards and their dry docks are industrial areas characterized by ship repair and maintenance commonly done on a dry dock to effectively work on avessel. Typically, abrasive grit blasting, metal cutting, and painting operations are conducted. Shipyard stormwater can be characterized as containing relatively high concentrations of metals, intermediate concentrations of solids, and low concentrations of oil and grease. There is a variety of technology for removing metals from dry dock discharges such as chemical precipitation, sedimentation, filtration and electrocoagulation. Effectiveness for all is dependent upon the media used as well as flow characteristics through the media. For example, sand can effectively removes particulate pollutants in solid form by filtration but is not effective for dissolved metals. Organic based filtration can provide enhanced treatment of dissolved constituents by filtration as well as pollutant removal processes by adsorption but is more effective on some chemical constituents than others. The results of the technology review indicates that a combination treatment structure needs to be used for full range effective treatment of all compounds, solids/dissolved, heavy metal precipitates/heavy metal dissolved. A further constraint for Marisco was the need for portability for ease of movement and transport to various discharge points.

6 As such, the portable treatment system is designed to effectively coagulate and precipitate, filter and use sedimentation to achieve State of Hawaii Department of Health, Clean Water Branch regulator levels of under 2.9 mg/l for copper and 95 mg/l for zinc. With chambers for precipitation and others for filtering, the use of reactive chemicals and contaminant attracting components allow the 3PF system to target copper and zinc. Hinton setting up test unit

7 The 3 PF system results in precipitated metal hydroxide in the sedimentation chamber. Treatment time allows for passive removal of heavy metals still in suspension or late forming metal hydroxides beginning the process of sedimentation. Resultant clear water is drawn out of the 3PF system above the sediment layer of metal hydroxides. This water has been tested for copper and zinc with ND non detect results. Components and substance attractors are used to insure the metal hydroxides that form stay consolidated and form into an easily removal sludge layer at the base of the 3PF system.

8 In drydock operations, it is envisioned that the 3PF system can be used over and over again with simple recharge of chemicals and cleaning of components. As such, though the technologies proposed indicate that treatment can be achieved in as little as three (3) hours or as much as 24 hours; there will be no harm in allowing sedimentation, precipitation and particle attraction to collectors to continue during non use periods. As well, since typical shipyard areas contain working equipment, storage of dry dock operational materials such as paint, sand grit, etc, it is recommended that grading or berm containment of working areas be constructed or renovated in such a manner as to collect stormwater runoff in a collection point that can then be directed into the 3PF system. In this manner, effective treatment of any waters effluent or stormwater associated with dry dock operations is achieved.

9 The 3PF system is intended to provide an age old solution to drydock wash waters and shipyard runoff treatment. Other solutions have been found to be 30 75% effective with costs increasing as removal efficiency rises. The 3PF system is intended to provide reasonable cost treatments with great efficiency and offers the shipyard industry a viable option for environmental compliance. If there are any questions, please feel free to contact: Mark Howland of URS Corporation at or mark.howland@urs.com Stephen Hinton of Marisco Limited at or shinton@marisco.net