Title : Sewer Outfall Quay Project-McMurdo Type : Antarctic EAM NSF Org: OD / OPP Date : December 30, 1992 File : opp93096 DIVISION OF POLAR PROGRAMS OFFICE OF THE ENVIRONMENT 202/357-7766 MEMORANDUM Date: December 30, 1992 From: Environmental Officer, DPP Subject: Environmental Action Memorandum (McMurdo Station Sewer Outfall Quay Reinforcement Project) To: Safety and Health Officer, DPP Facilities Engineering Projects Manager, DPP Environmental Engineer, DPP Environmentalist, ASA Commander, NSFA REFs: Environmental Impact Assessment (Improvement of Sanitary Wastewater Management at McMurdo Station, Antarctica), Dated December 29, 1989. Safety, Environment and Health Program Policy Memorandum 90-2. Authorization and Reporting Procedures for, Gathering and Use of Fill and Associated Activity, at McMurdo Station, Antarctica. Dated October 1, 1990. Environmental Action Memorandum (Blasting for, and Placement of, Fill Rock at McMurdo Station, Antarctica During the 1990-91 Season), Dated October 2, 1990. Memorandum, Subject: Review of "Environmental Assessment for Collection (and Placement) of Earth Fill Material," Dated November 17, 1990. Environmental Action Memorandum (Information on Dispersion of McMurdo Station's Wastewater), Dated March 1, 1991. Final Supplemental Environmental Impact Statement for the U.S. Antarctic Program, Dated October 1, 1991. Environmental Action Memorandum (Collection of Earth Fill Materials at McMurdo Station During the 1992-1993 Season), Dated December 1, 1992. This Environmental Action Memorandum describes the need for, and location of, proposed actions to reinforce and stabilize the domestic wastewater outfall quay at McMurdo Station, Antarctica. The Environmental Officer posed a set of questions relating to the proposed actions, and to the potentially affected environ- ment. These questions were responded to by Antarctic Support Associates, Inc.'s (ASA) Environmentalist, Terry Johnson; and Director of Engineering, Craig Martin on December 28, 1992; background information as well as the questions and responses are shown below: Background Wastewater at McMurdo Station, Antarctica, is collected in a heated pipe system, macerated and discharged directly into McMurdo Sound in accordance with provisions of the Code of Conduct for Antarctic Expeditions and Station Activities, and Annex III, Article 5 of the Protocol on Environmental Protection to the Antarctic Treaty. An outfall quay was constructed at the point of the wastewater discharge. The quay was damaged early in the 1990-1991 season by a grounded iceberg. It was partially destroyed early in 1991 by a severe storm. The quay has since been rebuilt, however, chances of further damage by similar circumstances is highly probable. Rebuilding the quay in an appropriate manner would require placing fill material such that it is not prone: 1) to being washed away by wave action; or, 2) damage from anchor ice. The actions proposed in this Environmental Action Memorandum have been the subject of intensive design engineering and would provide a greater level of protection against subsequent damage to the quay as well as reduce the total amount of fill materials required to repair any future damage. Cleaned, surplus fuel tanks would be filled with rocks, gravel and earth fill materials and emplaced so as to provide a breakwater along the outer margins of the quay. Environmental Assessment Queries and Responses GENERAL 1. What is the specific purpose of the proposed activity? The purpose of the proposed activity is to use cleaned fuel tanks filled with native rock and gravel to reinforce the quay which supports the above ground portion of the sewer outfall at McMurdo Station. The quay has been damaged by storms during the past seasons which has required extensive maintenance and repairs. The proposed reinforcements would provide increased resilience to such damage, as well as, reduce the amount of fill material needed for construction and maintenance. What alternatives to the proposed activity have the Program and the Contractor considered? 1. The proposed and preferred activity; 2. The use of unconsolidated rock and gravel to reinforce the quay; and 3. The "no-action" alternative. Have probable impacts of all alternatives been considered by the Program and the Contractor? Please explain how. Yes. 1. The impacts of the proposed and preferred activity would be primarily associated with the early stages of construction. Construction would temporarily increase the suspended solids content and turbidity of the seawater near the outfall and would disturb the portion of the shallow zone (0-6 meters in water depth) that is subjected already to annual scouring action by sea ice. Additional impacts would be associated with the collection of earth fill material required to fill the tanks. Collection of fill material at McMurdo Station is covered in separate Environmental Action Memoranda. In the latest Environmental Action Memorandum on that subject, it was estimated that approximately 380 cubic meters (500 cubic yards) of material would be required for the proposed activity. 2. The impacts associated with alternative 2 would be greater than those stated in 1 above. For the most part, a much larger amount of local fill material (estimated by ASA's Engineering Division to be approximately 760 cubic meters) would be required to construct a sound structure that would provide adequate protection from wave action and storms, and an additional 250 to 500 cubic meters would be required annually for maintenance. Also, placement of fill material would increase water turbidity near the quay through both the amount of material required and the frequency of its use. 3. No action would result in continued erosion of the quay and in the need to repeatedly rebuild the quay. This would require enormous amounts of fill material resulting in major impacts to the local environment. Should the chosen alternative involve potential impacts, how would these impacts be mitigated by the Program or the Contractor? The proposed activity is not expected to create any negative, long-term impacts. The proposed activity would actually have positive long-term impacts when compared to the alternatives considered. Short-term impacts would involve increased turbidity due to disturbance by construction activity of the shallow benthic zone nearest the quay. This area has been disturbed by past construction activities and is subject to repeated disturbance by sea ice that scours bottom sediments and their resident communities. When construction ceases the area would return to its previous state in a short period of time. During construction, fuel used by equipment would be carefully managed and construction wastes would be collected and disposed of according to U.S. Antarctic Program (USAP) waste management procedures. All fill material required for the project would be taken from borrow areas approved for such collection. The tanks to be used for the proposed project were previously used to contain fuel. These tanks would be thoroughly cleaned prior to the proposed use, and the wash water would be properly contained and stored for transport from Antarc- tica through the USAP's system of waste retrograde. Have measures to assess the indirect costs of the proposed activity been identified or considered by the Program or the Contractor? Please explain how. Yes. Indirect costs of the proposed actions are associated with the collection of earth fill material to annually maintain the quay. The proposed use of steel tanks filled with rock and gravel would greatly reduce erosion of the quay by wave action and thereby reduce the need to replace eroded material with fill. Reduc- tions in man-hours would be realized with gathering, transporting and placing fill material and with rehabil- itating fill gathering areas. In addition, there would be like reductions in fuel usage. LAND USE AND PLANNING 2. What is the specific location of the proposed activity? The location of the proposed activity is McMurdo Station, below the Water and Power Plant and just below the Waterfront Road. Have alternative locations been considered by the Program or the Contractor? If yes, which are they; if no, explain why. None have been considered the proposed actions are location specific. 3. How would any aesthetic impacts to the area from the proposed activity be handled by the Program or the Contractor? The proposed activity would have aesthetic impacts which would be handled in the most feasible manner. Admittedly, the use of old fuel tanks to stabilize the area may not have an aesthetically appealing appearance. However, the reductions in fill material requirements and the recycling of on-site materials offset the aesthetic impacts and provide sound bases for their use. Efforts would be made to integrate the tanks into the surrounding environment as best as is possible. 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. No, the proposed activity is expected to have no other in- direct impacts on the environment. 5. Would the proposed activity change the traditional use(s) of the proposed or chosen site? If yes, how; if no, why? No. The chosen site has been used for domestic wastewater discharge since 1986. 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 where the proposed activity would take place is suitable and has experienced some impact associated with placement of earth fill materials in the past. The pro- posed activity would have potentially positive impacts on the physical and environmental characteristics of the site by reducing the amount of labor and materials required for operation, repair and maintenance. IMPACT AND POLLUTION POTENTIAL AND ENVIRONMENTAL MANAGEMENT 7. How has protection of the environment and human health from unnecessary pollution 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 steps identified above to mitigate the impacts of the proposed activity are intended to protect human health and the environment. The overall purpose of the activity is to improve McMurdo's wastewater management system and to pro- vide higher degrees of public health and safety, and envi- ronmental quality. The proposed activity would decrease the need for fill material use and the impacts associated with its collection and placement. 8. Would the proposed activity change ambient air quality at the proposed or chosen site? If yes, how; if no, why? The proposed activity would have only temporary impacts on ambient air quality at the site through transitory increases in fugitive dust created by construction activities. Ambient air quality would to return to normal state whenever construction ceased. 9. Would the proposed activity change water quality or flow (drainage), at the proposed or chosen site? If yes, how; if no, why? Water quality is expected to change temporarily at the site through increased turbidity. This would occur during the construction stage when shallow sediments receive addi- tional amounts of substrate. 10. Would the proposed activity change waste generation or management at the proposed or chosen site? If yes, how; if no, why? Waste generation or management would not change at the chosen site. Rinse water would be produced during the cleaning of the fuel tanks. Rinse water, potentially containing hydrocarbon residues, would be collected, staged and retrograded from Antarctica. 11. Would the proposed activity change energy production or demand, personnel and life support, or transportation requirements at the proposed or chosen site? If yes, how; if no, why? No, the proposed activity would entail only minor and temporary changes in these areas during construction. 12. Is the proposed activity expected to adversely affect scientific studies or locations of research interest (near and distant, short-term and long-term)? If yes, how; if no, why? The proposed activity would not impact scientific studies in the short- or long-term. Sea water monitoring activities for the 1992-1993 season would be completed before construction would take place. 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 proposed activity would pose an adverse threat of pollution should an oil or fuel spill from heavy equipment occur during construction activities. Fuel will be carefully managed at the site to prevent this. Addition of earth fill-related particulates is expected to have less than minor and transitory impacts on marine benthic communities. 14. Does the site of the proposed activity serve as habitat for any significant assemblages of Antarctic wildlife (for example, mosses, lichens, antarctic birds or marine animals)? The quay itself does not serve as habitat for any significant assemblages of antarctic wildlife. The shallow marine zone (0-6 meters in water depth) has a gently sloping bottom that is heavily disturbed by the scouring action of sea ice in the shallowest depths and the formation of anchor ice throughout. Anchor ice is charac- terized by large ice crystals on the sea floor. Crystals form around such projections from the sea floor as benthic epifauna (e.g., such animals living on the sea floor as tunicates) and some infauna (e.g., such animals living in the sediments as polychaete worms). When buoyant enough, these crystals break free, lifting attached material from the bottom trapping it on the underside of the sea ice. This type of disturbance occurs to water depths of 30 meters; but denudes effectively the benthos to a water depth of 6 meters along the frontage of McMurdo Station. Invertebrates resident in this regularly disturbed zone include seastars, nemertean worms, sea urchins and opportunistic polychaete worms that invade during austral spring and summer months. This habitat is regularly modified by the introduction of sewage and by the scouring action of the sea ice as it pulls away from shore during the summer season; and impacts to resident communities from the proposed actions would be minor and transitory and would mimic the natural disturbance caused by sea ice. A second zone begins at about 6 meters water depth and contains increasing densities of invertebrates with increasing depth. Between 6 and 10 meters water depth, the sea floor slopes more steeply and sediments are looser. Infaunal communities increase in density and species richness, and there are occasional patches of the clam Laturnula elliptica. Epifaunal sea anemones grow on submerged objects. Below 10 meters the sea floor again slopes gradually with sediment of finer consistency. Dense assemblages of benthic infauna begin at about 20 meters water depth. Impacts to these communities from the proposed actions are not anticipated as suspended partic- ulates associated with construction are expected to rapidly sediment from the water column before reaching this zone; and, the proposed actions would lessen entry of unnecessary amounts of earth fill materials when the quay is subjected to future storms. A third zone begins sharply at 25 meters water depth, the habitat of a thick carpet of sponges. This mat extends into deep water. The habitat experiences little physical disturbance. Again, impacts to these communities from the proposed actions are not anticipated as suspended partic- ulates associated with construction are expected to rapidly sediment from the water column before reaching this zone; and, the proposed actions would lessen entry of unnecessary amounts of earth fill materials when the quay is subjected to future storms. HUMAN VALUES 15. Would the proposed activity encroach upon any historical property of the proposed or chosen site? If yes, how; if no, why? No. There is no historical property at the proposed site. 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)? Should the site be decommissioned in the future, the area would experience such minor and transitory impacts as those associated with construction. Finding The Environmental Officer, after reviewing the information provided above, believes that the proposed activity will pose less than minor and less than transitory impacts to the marine environment near McMurdo Station. The proposed activity is expected to have beneficial effects with respect to enhancement of domestic wastewater management at the station. With adherence to U.S. Antarctic Program policy on earth fill materials collection the proposed activity will improve the environment within and near McMurdo Station. The Program and the Contractor are authorized to undertake the proposed actions. Sidney Draggan Attachments