Title : Cnsctn. of containment-McMurdo's Tanks Type : Antarctic EAM NSF Org: OD / OPP Date : October 13, 1992 File : opp93078 DIVISION OF POLAR PROGRAMS OFFICE OF THE ENVIRONMENT 202/357-7766 MEMORANDUM Date: October 13, 1992 From: Environmental Officer, DPP Subject: Environmental Action Memorandum (Construction of Secondary Containment Around McMurdo Station's Bulk Fuel Storage Tanks) To: Safety and Health Officer, DPP Facilities Engineering Projects Manager, DPP Environmental Engineer, DPP Environmentalist, ASA Files (S.7 - Environment) This Environmental Action Memorandum describes the need for, and location of, proposed actions for establishment of secondary containment berms around McMurdo Station's Bulk Fuel Storage Tanks during the 1992-1993 austral summer, and beyond. The Environmental Officer posed a set of questions relating to the proposed project, and to the potentially affected environment. These questions were responded to by the civilian support contractor's Environmental Engineer, Ms. Carol Andrews; and Engineering Aide, Mr. Anthony Borcic on October 12, 1992; the questions and responses are shown below: Environmental Assessment Queries and Responses Background Currently, the bulk fuel storage tanks at McMurdo Station, Antarctica, do not have secondary containment. Secondary containment is necessary to prevent spilt or leaking fuel from entering the terrestrial or marine environment (i.e., McMurdo Sound) near the station. In the event of a catastrophic tank failure, containment berms would help control the extent of spillage and allow proper clean up of spilt fuel. In addition to the proposed construction of berms, high-level alarms are being installed in the tanks to reduce the potential for spills caused by overfilling. The existing tanks, approximately 20 years old, have been inspected and have been found by the civilian support contractor to be acceptable for continued use. The contractor proposes, therefore, installing secondary containment around the existing tanks rather than installing new, double-walled tanks. The containment system requires construction of earthen berms and placement of high-density polyethylene (HDPE) liners around the tanks. The volume of the containment area will be adequate to contain 110 percent of each tank's capacity. The timing of the project calls for installing secondary containment around tanks J-1, J-2, J-3, and J-4 during the 1992-1993 austral summer construction season. These four tanks are located in Tank Farm Two (see Attachments 1 and 2). Tanks J-1 and J-3 each have a capacity of 1,892,500 liters (500,000 gallons). Tanks J-2 and J-4 each have a capacity of 946,250 liters (250,000 gallons). The remaining tanks, including tank J-5 which is located in Tank Farm Two and has a capacity of 8,327,000 liters (2,200,000 gallons), are to receive secondary containment during subsequent seasons. GENERAL 1. What is the specific purpose of the proposed activity? The purpose of this activity is to install secondary containment around McMurdo Station's bulk fuel storage tanks so as to contain fuel spills and to prevent con- tamination of surrounding areas. What alternatives to the proposed activity have the Program and the Contractor considered? Five alternatives have been considered: 1) the proposed containment system consisting of HDPE-lined earthen berms; 2) a containment system using lined earthen berms with different designs; 3) replacing the existing tanks with new, double-walled tanks; 4) removing the tanks altogether; and, 5) no-action. Have probable impacts of all alternatives been considered by the Program and the Contractor? Please explain how. The impacts of the project as proposed include dust emissions due to fill-moving operations, alteration to existing surface water drainage and snow drifting patterns, and the impacts associated with fill gather- ing. (Earth fill gathering will adhere to current U.S. Antarctic Program policy; and the impacts of fill gathering at McMurdo Station during the 1992-93 season will be addressed in a separate document.) If the liner is punctured and a fuel spill occurs, some fuel release into the rock below the liner may also occur. One of the alternative designs considered by the contractor called for placing a small berm around the base of the tank. The liner would then be bermed up on both sides, creating a pool-like effect. However, one of the major design goals is to capture fuel leaking from the base of a tank in addition to above-grade spills. This would be difficult as it would be impos- sible to get the HDPE liner under the existing tanks. The contractor determined that by using the natural permafrost as a confining layer beneath the tank and placing the containment liner as shown on Attachment 2, page 2, the system would be much more likely to capture fuel leaking through a tank's bottom. A second alternative design would use a common berm between adjacent tanks. This would slightly reduce the quantity of fill material required for berm construc- tion. However, this design would increase the amount of liner required and reduce access to the tanks and surrounding piping. The contractor also considered a third alternative berm design. Under this alternative a retaining wall would be used to replace the unlined outer half of the berms to reduce the required amount of fill. However, to support the pressure of both the inner earthen berm and the hydrostatic pressure of fuel in the event a spill occurs, the retaining walls would have to be extremely strong. The walls would require below-grade anchoring such as large pilings. Such materials placed below grade would be difficult or impossible to remove when the berms are decommissioned, whereas the proposed berms could be regraded to a natural state containing only native materials. Also, retaining walls would require importing a large quantity of material for their construction. Replacing the existing tanks with new, double-walled tanks would have a number of impacts in addition to a significant increase in cost. A large amount of cargo space would be required to deliver new tanks and to retrograde the old tanks. Also, providing secondary containment would be delayed because the new tanks could not be installed until the 1994-95 season. Removing the tanks altogether would be feasible only if fuel was no longer required to support McMurdo Station and its related activities. Although steps are being taken to increase efficiency of fuel use, and to consid- er alternative energy sources, there will be a need to store fuel on site for the foreseeable future. If no action is taken the tanks would continue to be used without secondary containment. A large fuel spill at a bulk storage tank could be caused by a number of factors, including structural failure of the tank itself or such outside influences as a vehicle or rock debris puncturing the tank. At best, the fuel would soak into surrounding rock which would have to be excavated and retrograded (unless on-site treatment were possible). The volume of contaminated rock resulting from rupture of one of the smallest tanks 946,250 liters (250,000 gallons) would be approximately 3800 cubic meters (5,000 cubic yards), enough to fill 100 six-meter-long milvans (based on the typical 1:4 ratio of spilled fuel to contaminated rock). In the worst case the fuel would flow down drainage ditches into Winter Quarters Bay or into McMurdo Sound. The ecological effects of split oil reaching open water could be devastating to all marine life. Should the chosen alternative involve potential impacts, how would these impacts be mitigated by the Program or the Contractor? The contractor would take the following steps to mitigate the impacts of the proposed activity: 1) To minimize dust emissions and maximize compaction the contractor would wet the fill material using a water truck. 2) The berm locations and final grade around the berms would be selected to avoid interrupting existing surface water drainage patterns and to avoid causing ponded water. 3) Blowing snow may accumulate in the bermed areas. The contractor, as part of maintenance of the fuel storage and distribution system, would inspect the containment systems in October and February at a minimum. Snow accumulated over the winter would be removed carefully to maintain the capacity of the containment system. Snow or water that accumulates inside the berms during the summer would be swept or pumped out, as necessary. 4) To ensure that the liner is free of leaks the contractor would follow standard liner installation practices. This would include ensuring no sharp objects are placed on or below the liner and testing liner seams for leaks and weld strength. The con- tractor would inspect the liners for tears and punctures visually as part of the semiannual inspec- tions and would repair the liner as necessary. Have measures to assess the indirect costs of the proposed activity been identified or considered by the Program or the Contractor? Please explain how. The inspection and maintenance activities discussed above would increase the workload of the Contractor's maintenance department. LAND USE AND PLANNING 2. Where would the proposed activity be located, specifically? The containment systems planned for installation during the 1992-93 summer season would be placed around tanks J-1, J-2, J-3, and J-4 which are located in Tank Farm Two (in the pass between McMurdo Station and Scott Base; see Attachments 1 and 2). During subsequent seasons contain- ment systems also would be placed around Tank J-5 (also in Tank Farm Two) and around the rest of the bulk fuel storage tanks. This includes the tanks on the hill north of town and the one remaining tank on Hut Point. Have alternative locations been considered by the Program or the Contractor? If yes, which are they; if no, explain why. No. The secondary containment locations are dictated by the existing tank locations. 3. How would any aesthetic impacts to the area from the proposed activity be handled by the Program or the Contractor? The contractor would maintain the construction site in a neat and orderly manner. Although the containment systems themselves may not be considered attractive, as evidence of environmental protection measures they may be considered a visual improvement. 4. Would the proposed activity have any other indirect impacts on the environment? If yes, what are they; if no, explain why none are expected. Berm construction would require a large quantity of fill. Fill gathering would require blasting and removing rock from a quarry. Fines would be obtained by scraping material off the surface over large areas. The impacts of these activities will be addressed in a separate document regarding McMurdo Station fill-gathering activities for the 1992-1993 austral season. The following quantities of fill material are estimated to be needed for berm construction: Tank Total Volume of Fill Required 旼컴컴컴쩡컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴커 쿕-1 � 1800 cubic meters (2,400 cubic yards) � 쿕-2 � 700 cubic meters (900 cubic yards) � 쿕-3 � 1800 cubic meters (2,400 cubic yards) � 쿕-4 � 700 cubic meters (900 cubic yards) � 쿕-5 � 8000 cubic meters (10,500 cubic yards)� 읕컴컴컴좔컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴켸 5. Would the proposed activity change the traditional use(s) of the proposed (or chosen) site? If yes, how; if no, why. No. The sites would continue to be used for fuel storage. 6. Are the physical and environmental characteristics of the neighboring environment suitable for the proposed activity? If yes, explain why; if no, explain why. Yes. The area around the tanks in The Pass is generally flat and suitable for berm construction. The area is characterized by a high degree of human activity and is, therefore, suitable for installation of manmade structures. IMPACT AND POLLUTION POTENTIAL AND ENVIRONMENTAL MANAGEMENT: 7. How has protection of the environment and human health from unnecessary pollution or impact been considered for the proposed activity (includes such considerations as pollution abatement or mitigation, and waste management [e.g., of noise, dust, fuel loss, disposition of one-time-use materials, construction wastes])? The purpose of the activity is to decrease unnecessary pollution by reducing the potential for fuel loss to the environment. Because the main environmental impact of the project is related to the quantity of fill material required, the contractor has attempted in the proposed design to minimize the quantity to be used. 8. Would the proposed activity change ambient air quality at the proposed (or chosen) site? If yes, how; if no, why. Air quality would be temporarily affected by dust and exhaust emissions from earthmoving equipment. After berm construction is complete the containment systems would not affect air quality. 9. Would the proposed activity change water quality or flow (drainage), at the proposed (or chosen) site? If yes, how; if no, why. Yes. The berms would necessarily form "ponds" around the tanks. The Contractor would grade the area outside the berms to establish appropriate drainage and to prevent unnecessary ponding. 10. Would the proposed activity change waste generation or management at the proposed (or chosen) site? If yes, how; if no, why. No. A small amount of HDPE liner material may be retro- graded as construction waste. However, the cost of the liner provides incentive to minimize liner waste. 11. Would the proposed activity change energy production or demand, personnel and life support, or transportation requirements at the site? If yes, how; if no, why. The project would increase temporarily the personnel demand at the station. Construction during 1992-93 would require four persons working full-time for approximately 17 weeks plus a foreman overseeing the project. 12. Is the proposed activity expected to adversely affect scientific studies or locations of research interest (near and distant, in the short-term and in the long-term)? If yes, how; if no, why. No long-term adverse effects on scientific studies are expected. In fact, by preventing an uncontrolled fuel release from contaminating surrounding areas and possibly the ocean, the proposed activity would help maintain a relatively pristine environment for scientific studies. Any dust generated at the site should not affect experi- ments at the Cosmic Ray laboratory. The contractor would coordinate with Idaho National Engineering Laboratories to ensure the activity does not interfere with ambient air quality monitoring planned for the 1992-93 austral summer season. 13. Would the proposed activity generate pollutants that might affect terrestrial, marine or freshwater ecosystems within the environs of the station or inland camp? If yes, how; if no, why. No. The pollutants that may be generated during construc- tion are limited to dust and pollutants contained in exhaust from the construction equipment. The quantity of these pollutants would be minimized to the extent possible and is not expected to affect surrounding ecosystems. 14. Does the site of the proposed activity serve as habitat for any significant assemblages of Antarctic wildlife (for example, mosses or lichens, or antarctic birds or marine mammals)? No. Wildlife in the area is limited to skuas. There are no known skua nesting grounds in the area immediately around the Tank Farm Two area where secondary containment would be installed during the 1992-93 season. HUMAN VALUES 15. Would the proposed activity encroach upon any historical property of the site? If yes, how; if no, why. No. The areas around the existing bulk fuel storage tanks are not on the Ross Island list of historic sites. OTHER CONSIDERATIONS 16. What other environmental considerations may be potentially affected by the proposed activity at the proposed (or chosen) site? For example, have impacts associated with decommissioning of the activity been considered (and how). The berms and liner would be completely removable. One of the advantages of constructing earthen berms over using retaining walls to form containment around the tanks is the fact that no permanent structures such as pilings would be used. Finding The Environmental Officer, after reviewing the information presented above, believes that the proposed activity, if conducted as described in this Environmental Action Memorandum, poses less than minor and less than transitory potential impacts to the environment within or near McMurdo Station, Antarctica. There are, in fact, recognized environmental and safety benefits associated with completion of the proposed action. The contrac- tor and the Program are authorized to proceed with the proposed activity. Sidney Draggan Attachments