Cold Regions Engineering: Cold Regions Impacts on Transportation and Infrastructure

Over 124,300 heat pipes were installed in vertical support members on the Trans-Alaska Pipeline System. During infrared, IR, surveys in the early 1980's it was observed that cold topping was occurring on some of these heat pipes. The cold topping was due to an accumulation of non-condensable gases, a by-product of corrosion or chemical dissociation of anhydrous ammonia, in the problem heat pipes. Alyeska Pipeline Service Company under took an experimental program, beginning in the fall of 2000, to measure the heat transfer performance of NCG blocked heat pipes. Results of this test program are presented and discussed showing the reduction in heat transfer performance of the heat pipes as a function of hydrogen blockage levels. Infrared images are also presented showing the increase in cold topping as the amount of hydrogen in the heat pipe is increased. These IR images are correlated with the degradation in heat transfer performance. A thermodynamic analysis is also presented showing the relationship between the mass of hydrogen within the heat pipe and apparent blockage as a function of evaporator and condenser temperatures.

In its 800 mile (1280 km) route from Prudhoe Bay to Valdez, the 48-inch (1200 mm) Trans Alaska oil pipeline traverses varied hydrologic zones ranging from the barren Arctic North Slope to the rugged Brooks and Alaska ranges to the glacier fed streams in the Valdez area. The pipeline involves 80 major buried or elevated river crossings and more than 50 miles (80 km) of instream and floodplain alignments either deep buried or protected by river training structures. The design faced unique and challenging conditions on a project wide scale such as massive channel icings, sudden and dramatic flood releases from glacier-damned lakes and sediment deposition and channel changes in alluvial fans and steep braided rivers. The hydrologic and river engineering data and knowledge base available at the time of TAPS' design and construction in 1973 – 1977 was limited particularly in the uninhabited north half of the project. The performance of river training structures — key to the integrity of the line in many locations — in steep braided arctic rivers had been largely untested. This paper addresses the general performance of the river crossings and river training structures, now in place for 25 years, via lessons learned from four major floods. Several floods were well in excess of the Pipeline Design Flood. A record high outburst flood from a glacier-damned lake was experienced at a major bridge crossing. Recently, severe icings and flooding was experienced at two locations where previously no significant icing problems occurred. The river training structures have performed well. Primarily, the post-flood works required have involved new structures where the pipeline is parallel to the major river systems. The lessons learned are valuable for the continued safe operations of TAPS as well as for the planning and design of future pipelines, especially those located in Arctic regions.

The two slopes approaching Squirrel Creek were modified during construction because natural slopes in the area of similar steepness were displaying landslides. The original design plans called for the pipe to be buried on these slopes. When drilling found discontinuous, warm permafrost along these slopes, the pipe design mode was changed to aboveground with heat pipes to maintain frozen ground. Since construction of the Trans Alaska Pipeline System (TAPS), Alyeska Pipeline Service Company (ASPC) has been monitoring instrumentation on these slopes and performing periodic maintenance. This paper will describe the history of the performance of these slopes and the maintenance activities that have been employed to address some of the issues that have developed along the slopes since construction. Documented solifluction-like movements, changes in ground thermal state, frost heave, and thaw settlement have all been monitoring and addressed with maintenance.

There are approximately 78,000 Vertical Support Members (VSM) on the Trans-Alaska Pipeline System (TAPS). A small fraction of VSM have tilted over time, primarily as a result of frost heave. Corrective maintenance to address this situation, which can include VSM replacement, is very expensive. As an alternative, a model was developed to determine if, and when, VSM integrity would be compromised beyond acceptable factors of safety to the point where the pipeline foundation would be jeopardized. The model was finite element based, using non-linear soil elements to simulate the subsurface resistance. This paper reports on the model and a summary of the results.

Five areas within Alyeska Pipeline Service Company's (Alyeska's) Valdez Marine Terminal (VMT) have steeply cut rock slopes that have been reinforced with rock bolts and monitored since the VMT was constructed. Monitoring has included regular reading of pneumatic piezometers that were installed in the slopes during construction. Flag levels were established for each piezometer on these slopes based on stability calculations or historical water levels. Annual reports are prepared to compare groundwater levels at each piezometer during that year to the established flag levels. If flag levels are exceeded, engineering reviews are made to assess the potential impacts of these excursions. Some piezometers have required maintenance and repair, and some rockbolts have required maintenance to maintain them to the standards assumed by the slope designers. Scaling and localized shotcreting have be required in some areas to control the potential for rockfall. This paper addresses the history of one of the VMT slopes, presents some of the long-term monitoring data, discusses the meaning of the data, and describes the maintenance activities that have taken place on the slope.

Buried secondary containment liners at several pump station tank farms along the Trans Alaska Pipeline System (TAPS) were evaluated in 2000 to determine if they complied with the Alaska Department of Environmental Conservation oil pollution prevention regulations under the Alaska Administrative Code, Title 18, Chapter 75 (18 AAC 75). These secondary containment systems (SCSs), which were constructed in the mid to late 1970's, are diked areas composed of a flexible membrane liner covered by an average of about 0.61 m of soil that surround the pump station tank farms. Golder Associates Inc. performed a comprehensive assessment of the tank farm liner systems at five pump stations that included a qualitative examination of project records, the development of a visual inspection checklist, and select test pits at each pump station tank farm to confirm that the liners met regulatory requirements. The field investigation also included using geophysical techniques, such as ground penetrating radar and electric leak detection surveys, to identify potential liner damage locations. Based on the liner damage identified at each pump station tank farm SCS, leakage rates were calculated and compared to leakage rates through a soil liner with a permeability of 1 x 10^–6 cm/sec.

McCallum Creek crosses the Trans Alaska Pipeline in the Central Alaska Range near Paxson, Alaska. It was converted from a braided channel on an alluvial fan to a stable single thread channel at the pipeline crossing. Objectives included controlling the position of the channel at the pipeline crossing and minimizing aufeis accumulations through the converted reach. A natural channel design methodology was used, which involves determining the dimension, pattern, and profile of a stable reference reach for the associated valley type and stream type and emulating those characteristics in the design reach. A failure mode analysis was conducted. Mitigative measures were incorporated into the design for each potential failure mode. The channel was lowered to reduce surface energy loss and associated winter aufeis accumulations. The site has been subjected to at least one bankfull flow event since construction was completed in May 2000. Performance has been good during the 2000 and 2001 summer seasons. Aufeis accumulations have not recurred since the channel conversion. Lessons learned are presented from this and several similar projects constructed along TAPS in 2000 and 2001.

The aboveground support system of the Trans Alaska Pipeline System was extensively analyzed during the initial design phase of the pipeline to ensure integrity during operational and contingency loading conditions. These analyses assumed the position of the pipeline on the beam supported by the Vertical Support Members (VSM) were within defined operational bounds. The original design analyses did not include an analysis of the pipe when the pipe position on the support beam during operational conditions placed the insulation of the pipe in contact with a VSM. During an audit of the pipeline, the pipeline insulation was identified to be in contact with a VSM at a number of locations, and identified as a potential risk to the pipeline integrity during a seismic event. This paper describes the series of analyses performed to address this operational situation, as well as the relatively small, remedial construction required as a result of these analyses and the recommended continued monitoring program.

An important aspect of the ongoing operation of the buried sections of the Trans-Alaska Pipeline System (TAPS) is the curvature imposed on the pipeline by differential settlement of the surrounding soil as a result of thawing of ice-rich subsurface soils. High pipe curvature is a source of concern since it can potentially lead to wrinkling of the pipe wall and/or tensile fracture of the pipe at girth welds. Alyeska Pipeline Service Company has monitored pipeline settlement using different techniques since start up of the line in 1977. This paper provides a brief historical overview of how the techniques used to monitor pipe settlement have evolved over the life of TAPS. The paper also provides a discussion of the how the pipe geometry is currently monitored using the BJ Pipeline Inspection Services (BJ) Geopig® "smart" pig. The discussion includes a brief description of the Geopig measurements which are numerically processed to obtain the three-dimensional pipeline displacement and curvature (bending strain) profiles. Several illustrations of this technology are presented. The paper concludes with a summary of how Alyeska's state-of-the art pipeline geometry monitoring program is used to help make decisions related to maintaining the structural integrity of TAPS.

Useful life is defined as a combination of design life, physical life, and economic life. The useful life of TAPS can be described as the period during which the pipeline provides a safe, environmentally sound, economically viable transportation link to get Alaska North Slope crude oil to market. Useful life is also one of the three primary elements for establishing the duration of the federal and state rights-of-way for TAPS, the others being serving a public purpose or benefit, and the ongoing facility costs. This paper addresses the following issues with special emphasis on facility aging and life-cycle issues associated with operating a warm crude oil pipeline in cold regions: 1) TAPS design life is based on the incorporation of robust components coupled with system monitoring programs designed to detect and counteract aging and facility use factors, 2) TAPS physical life can be virtually unlimited given the execution of appropriate maintenance, repair and replacement programs, and 3) TAPS economic life is governed by the extent of recoverable North Slope crude oil reserves. Predictions show these reserves being produced in quantities sufficient to support the continued operation of the pipeline well into the 21^st century.

In 2001, the Trans Alaska Pipeline System (TAPS) owners produced a comprehensive analysis of the impacts associated with the renewal of the TAPS rights-of-way. The resulting report, Environmental Report for the Trans Alaska Pipeline System Right-of-Way Renewal, described the physical, biological, and socio-economic impacts of right-of-way renewal — and of non-renewal. The Environmental Report followed the guidelines of the Council on Environmental Quality for preparing environmental impact statements (EISs). Since projections of future impact of TAPS operation closely follow post-construction impacts since 1977, an assessment of the impact of 25 years of operation of a warm oil pipeline in cold regions can be described. This paper reviews the results of the report with special emphasis on physical impacts. Because the pipeline system has been in continuous operation since 1977 and is under stringent regulatory controls, its effects on the physical environment — terrestrial, air quality, and water quality — are known to be relatively minor and can reasonably be expected to continue without significant change. Justification for predictions of low impact can be summarized in the following conclusions: 1) The TAPS pipeline and related facilities already exist with known, observable impacts; 2) Major changes to the pipeline system or to the affected physical environment are not expected; 3) New surface-disturbance areas associated with TAPS will be small and isolated; 4) There would be no unavoidable adverse effect on the physical environment that would not be mitigated to the extent technically feasible; and 5) Declining throughput could result in lower emissions and discharges affecting air and water quality.

Permafrost areas present unique problems to the design and performance of buried flexible structures. All buried flexible structures depend on soil-structure interaction for support. Generally the structure will not support itself under the imposed loads, and the backfill around the structure must be designed to provide support. An analysis of the soil-structure interaction must be made. The natural soil outside the select backfill envelope must also provide sufficient support. The natural soil outside and beneath the structure is, therefore, very important to the stability of the structure. In addition to normal design considerations a buried flexible structure on permafrost must take into account the potential for thawing of the permafrost, ice lenses, excavation of permafrost, and other considerations unique to arctic areas. This paper presents the methodology for evaluation of a buried flexible structure consisting of a circular flexible metal pipe, 22 feet (6.7m) in diameter in a permafrost area. The hypothetical structure is to be placed beneath a stockpile consisting of 80 feet (24.4m) of zinc ore weighing 185 pcf (29 kN/m³). In addition to the normal problems associated with high loadings on flexible buried structures, this structure is to be founded in an ice rich permafrost area.

In order to understand the complex behavior of gas pipelines in arctic regions, a full-scale experimental pipeline was constructed near Fairbanks, Alaska in December 1999. The pipeline was laid 1.8 m below the ground surface and covered with 0.9 m thick silty-sandy soil. The first 30 m of the line is in permafrost and the remaining section is in unfrozen ground. During the first phase of monitoring, chilled air with temperature between –4°C and –14°C was circulated through this 105 m long pipeline. The ground temperature measurements indicated that a frost bulb had developed in the non-permafrost ground. The mean monthly average temperature measured by the thermal fences indicated that the ground 2.0 m deep and 1 m away from the pipe center was reduced from –1.22°C in December 1999 to –4.6°C in December 2000. During the same period, the mean ground temperature at the 4 m depth gradually diminished from 0.18°C to –0.72°C and from –0.1°C at –0.18°C at the 8 m depth. Vertical upward movement of the pipeline caused by a frost front migrating out from the pipeline was noted. The maximum movements of the pipeline were 99.0 mm in the unfrozen area, 90.1 mm near the permafrost-non permafrost boundary, and 69.1 mm in the permafrost area. An empirical equation was developed to describe the ground temperature change. The statistical analysis indicated that air temperature had a less effect on the immediate ground (i.e. < 2 m from the pipeline center) than the pipeline temperature.

As part of the Alpine development project, Phillips Alaska, Inc. has installed a 305 mm (12-inch) diameter utility line and a 356 mm (14-inch) diameter produced oil line between the Alpine and Kuparuk oil fields on the Alaskan North Slope. In sections of the pipeline alignment that are oriented nominally perpendicular to the prevailing wind directions, a system of pipeline vibration dampers (PVDs) has been installed to mitigate potential fatigue damage due to wind-induced vibration (WIV). As part of the right-of-way agreement for the pipelines, Phillips has implemented a pipeline WIV monitoring program with the objectives of insuring that the PVD systems are performing as designed and to confirm that the spans without PVDs are not experiencing frequent and significant WIV. The Alpine WIV monitoring systems represent the most extensive, long-term WIV monitoring program ever undertaken on the North Slope. This paper provides an overview of the Alpine pipelines WIV monitoring program including; a description of the layout of the instrumentation, the data acquisition and the power supply systems, and a description of commissioning these systems. A summary of the WIV monitoring approach and the pertinent wind observation and vibration data gathered is also provided. The paper concludes with a summary of the overall findings and conclusions from this program.

This paper briefly describes the information gathered and conclusions reached during Phase 1, Potential Corridors Identification, of the Resource Transportation Analysis (RTA). The RTA is a component of the Northwest Alaska Transportation Plan, which will provide a strategy to guide transportation infrastructure development in Northwest Alaska. The study area covers approximately 564,300 square kilometers of northern Alaska. It encompasses the entire North Slope Borough (NSB) west of the Dalton Highway, the Northwest Arctic Borough (NWAB), the Yukon River Basin west of the Dalton Highway and north of Nenana, and the Seward Peninsula and Norton Sound region. Resource districts in the study area are the DeLong Mountains District, Ambler Mining District, Seward Peninsula District. Ruby District, Wiseman and Chandalar districts, and North Slope District, which includes the Western Arctic District. The paper summarizes the known reserves of mineral resources, including oil and gas, lead, zinc, copper; coal, gold, platinum, and other hard minerals. The environmental and land status, transportation options, and financial issues associated with each potential mining district are summarized in this paper. Cold regions impacts on the study include climate, sea ice, and permafrost.

The Whittier Access Project is the 8.4 km (5.2 mile) extension of the Portage Glacier Highway to Whittier Alaska. This project provides the first highway access to the port community of Whittier, Alaska—a vital cargo port, recreation area, and tourist destination located on magnificent Prince William Sound. This paper gives an overview of the history of the project, alternatives considered, and some of the challenges successfully conquered during the construction. The harsh environmental conditions at this location required an innovative design to provide a facility that would meet the needs of the public.

The Anton Anderson Memorial Tunnel was recently reconstructed to become the longest highway tunnel in North America and the only tunnel shared by both highway and rail traffic. The project is located about 50 miles southeast of Anchorage in an area with little historical data that could be used to develop design criteria. This paper illustrates the development of the design criteria for the project, identifying the roles of the owner, owner's consultants and the design-build team's designers. Several examples are presented including the development of design criteria for egress/refuge, wind loading, snow loading including avalanche loading, tunnel drainage, ventilation, ice control structures and the unique traffic control system that allows joint highway and rail use of the tunnel.

Recently converted to a dual use highway/railroad tunnel, the 4.0 km Anton Anderson Memorial Tunnel in south central Alaska provided more than its share of water- and ice-related problems to the design/build contractor. Previously, water inflows and associated ice build-up had been significant maintenance tasks for the Alaska Railroad in winter months. There had also been on-going degradation of the track structure due to frost heaving and the effects of water and ice. On June 7, 2000, the converted tunnel was opened to the public with a new roadway structure and an active ice control system. This paper details the approach and solution to the problem of ice build-up.

Located on the polar plateau at an elevation of 2,835 meters (9,301 feet) above sea level, the South Pole is arguably the most pristine and extreme environment on earth. To the worldwide community of scientists, it offers a unique platform for scientific research including aeronomy, astrophysics, glaciology, climatology, and seismology. The Amundsen-Scott South Pole Station (United States) is situated on the plateau within one hundred meters of the geographic South Pole. Operational since 1956, Amundsen-Scott is undergoing its second significant reconstruction and modernization. To extend the station's useful life, minimize the operational energy it consumes, and provide a healthy habitat for its occupants, the new station incorporates a number of sustainable design strategies. Many of these strategies are uniquely suited to the climatic conditions of the polar plateau. This paper will briefly introduce the philosophy of sustainable design, describe the primary sustainable characteristics of the Amundsen-Scott South Pole Station, and discuss how the station's innovative design could set the standard for future development of the polar plateau.

A study was conducted to determine the adequacy of the aircraft rescue and fire fighting (ARPF) capabilities at the U.S. Antarctic Program's (USAP) airfields in Antarctica. Realizing that many of the civilian and military standards and regulations that normally govern the ARFF requirements for airports would not be applicable at the USAP airfields, a performance-based approach was used to analyze the risks and potential fire hazards associated with airport operations in the Antarctic environment. Typically, existing ARFF regulations require that significant quantities of a foam/water agent be available to support aircraft fire fighting and rescue operations. Given the environmental conditions in Antarctica and the effect they have on potential fire hazards, the analyses indicate that adequate protection can be provided using primarily a dry chemical agent, thus obviating the need to provide special measures to prevent the foam/water agent from freezing. However, very little data are available to allow a quantification of the amount of dry chemical agent needed and the methods/strategies for proper application in combating the various postulated fires scenarios.

Tunneling in cold regions presents many unique engineering challenges. When that region is the South Pole, these challenges become extreme. In 1996, the U.S. Army Cold Regions Research and Engineering Laboratory first deployed the South Pole Tunneling System. This system was designed and built specifically for machining tunnels in the firn (highly compacted snow) of the Antarctic ice cap. The tunneling machine creates 2- x 3-m tunnels through the material at depths of up to 16 m. A pneumatic chip disposal system transfers the debris to the surface, where a centrifugal fan powers the disposal system. This system has been used to create two tunnels for water and power transport in support of the new South Pole Station currently under construction. This paper will discuss some of the engineering challenges faced by both the designers and operators of the equipment over the course of four deployments.

This paper investigates claims of high guardrail damage rates for guardrail end terminals in high snowfall areas and recommends a selection of terminals for use in high snowfall areas based on an evaluation of end terminal specifications and a survey of eight northern tier state Departments of Transportation (DOT) that use these terminals. In areas of significant snowfall levels and cold temperatures, agencies need an end terminal that can withstand these conditions, resist damage during snow removal activities, and be readily repaired without having to excavate or drive posts into frozen ground. Furthermore, any viable end terminal must meet the National Cooperative Highway Research Program (NCHRP) Report 350 standards. This paper recommends eliminating all terminals that do not use sleeved steel posts. Wooden posts tend to shear-away at the top of the soil tube whereas steel posts can be replaced year-round. Part of minimizing the danger to the end terminals during snow removal activities relies on more effective marking strategies and improved awareness and caution among winter maintenance crews. While this study ranks all of the alternative end terminals, those without steel posts and a limited percentage of posts sleeved cannot be recommended. Two terminal types, the sequential kinking terminal (SKT) and the ET-2000, emerge from the evaluation as the preferred designs for high snowfall regions because they use steel posts and sleeve all of their posts. While many of the other alternatives may prove adequate for many sites, only the ET-2000 and SKT are recommended for use in high snowfall regions at this time. More research is required to identify a single terminal as the best alternative because the user data exhibits limited variability.

A presently ongoing Nordic project "Exclay Intemordic Geoproject" aims at research into an overall utilization of expanded clay (exclay) in road embankments. One part of the project is concentrated on skid-resistance of exclay insulated and lightened roads, as insulation close to the road surface may prevent heat transfer from the underlying embankment and cause icing on the road. For this purpose two test sites were constructed with exclay insulation at different depths. This paper discusses temperature, dewpoint, skid-resistance measurements and temperature modelling at the Tuupakka test site and the applicability of the results to the purposes of the project.

In this study, the traction performance of transit and paratransit vehicles was evaluated on snow and ice surfaces. Field tests were conducted in Fairbanks, Alaska, using three types of vehicles: 1) a 41-passenger transit bus; 2) a 32-passenger transit bus, and 3) a 9-passenger paratransit vehicle. Each vehicle was tested for different combinations of tire types that included highway tires, snow tires, studded-siped tires, highway 3-rib tires, all-season tires, and snow siped tires. Winter traction performance was evaluated using a number of tests that included stopping distance, starting traction, hill-climbing, cornering, and controllability. Results indicate that winter traction performance is significantly influenced by vehicle type, tire combination used, and the road surface condition (compacted snow or ice). Research findings and recommendations for appropriate tire combinations that are most suitable for winter traction are presented.

Several Federal Aviation Administration (FAA) specifications for base and subbase materials were evaluated with respect to frost heave and thaw weakening. The study included both unstabilized and stabilized materials. Most of the unstabilized materials allowed up to 15% fines passing the no. 200 sieve, with the exception of the crushed aggregate base, which allowed no more than 8% fines, and the sand-clay base, which allowed up to 25% fines. The Corps of Engineers (COE) frost-susceptibility criterion was used to delineate the frost susceptibility, while the time to drain a base or subbase layer was used to determine the thaw-weakening potential. The subbase (P-154) and the crushed aggregate base (P-209) met the COE frost-susceptibility criterion, but none of the materials met the COE drainage requirements. However, if the fines contents of the base or subbase were reduced to less then 3%, they did meet the criterion. The resilient modulus of cement-treated soils remained at the level found before freezing, when the cement content was greater than 5%.

Spring thaw is a critical time of year for road deterioration. The types of deterioration or distresses most common during spring on unpaved roads are rutting and roughness, which is often in the form of washboards (also called corrugations). These distresses were observed over several years and were studied using standard pavement deterioration models, such as MMOPP (Mathematical Model of Pavement Performance). These types of models are usually designed for paved roads, and are sometimes limited in their options for soil characterization and manipulation of the forces at the road-tire interface. Therefore, a finite element model of the tire-road interaction was also developed. Various finite element models were generated to simulate an unpaved secondary road subjected to local vehicle traffic. These models were implemented in a three-dimensional dynamic analysis with a wheel rolling over the soil. Simulations of the unpaved road were used to study the effects of vehicle speed, load, suspension system, wheel torque, wheel slip, etc., on rutting and washboard formation. Results are discussed with regard to field measurements and observations.

Frost heave in fine-grained soils below roadway pavements causes extensive and costly damage. In order to mitigate frost heave and associated damage, a geocomposite drainage net was installed in highway test sections along a 3.0 km reconstructed portion of US Route 1A in Frankfort and Winterport, Maine, to function as a capillary barrier to reduce frost heave and a drainage layer to accelerate thaw recovery. This section of road had previously been plagued by pavement cracking, rutting, and potholes requiring frequent and costly maintenance to maintain a trafficable pavement surface. Thermocouple strings were embedded in the test sections at six-inch (152-mm) vertical intervals and temperatures were recorded with depth within the section. Ambient air temperatures and roadway elevations were also documented. This paper deals only with the influence of the geocomposite on frost heave. The freezing index, frost penetration and heave for the winter of 1997–1998, immediately after construction are reported. The results suggest some benefit when the geocomposite is placed within the subgrade. It appears that the primary benefit of the geocomposite is that it provides dewatering benefit during spring thaw—probably controlling the elevation of the water table. There may also be an effect of the cut/fill depths that masked the effectiveness of the geocomposite drainage layers.

A questionnaire and a literature study were conducted to collect information from private contractors regarding the emissions produced when using polymer-modified asphalt (PMA) pavements in cold regions. The purpose of the study was to investigate if the emissions could be eliminated or reduced with existing experiences and information. The emphasis of the study was to investigate factors such as equipment, method of mixing asphalt and aggregate, fuel used to heat aggregate, and the materials used that might be causing the emission problems. On the basis of the research, it was concluded that the existing mixing plants are mostly drier drums older than 10 years, and the asphalt is mixed with aggregate through superheated air in the drum. The most commonly used fuel is diesel #2. The materials used included base asphalts AC-5 and AC-2.5, SBS and crumb rubber modifiers, and proprietary blends. Based on the small amount of materials used by the questionnaire responders, it was impossible to determine which materials create most emissions. Recommendations were given to reduce emissions by using batch plants or modifying existing dryer drums to include special compartments for the mixing of asphalt with the aggregate, and by not exceeding the ideal mixing temperatures.

In northern climates, frost action is a major cause of pavement deterioration. It is well known that freezing temperatures in frost susceptible subgrade soils cause the pavement to heave. The resulting displacement imposed to the pavement can be substantial, reaching 100 to 200 mm in severe cases. When spring thaw occurs, segregated ice melts generating high pore pressures in frost susceptible subgrades. The bearing capacity loss can be substantial, leading to important structural damage to pavement exposed to severe and uncontrolled loading conditions. Considerable research efforts have been devoted to the characterization of soils and material properties and their variation as a function of moisture and temperature variations. These research initiatives are typically conducted in the field using deflexion measurements or in the laboratory using cyclic triaxial testing. The use of these research results typically requires assessing seasonal fatigue damage using analytical techniques to compute stresses and strains at critical location in pavement structures and empirical damage models. A new approach based on a mechanistic index is proposed. The index is taking into consideration the amount of water accumulated by the freezing process, the rate of thawing in pavement layers and in the subgrade soil and the rate of consolidation of the pavement structure. The paper will describe the theoretical development of the new index and will present correlation between the index and the characteristics of observed weakening (intensity and duration) during spring thaw.

Pavement evaluation in cold regions is focused on the distress to pavements during the thaw-weakening period. To minimize the damage to the pavement structure, state DOTs apply load restrictions for a certain period of time. The length of the load restriction period has a significant impact on the logging and trucking industries. Over the years, state and federal agencies have developed empirical and semi-mechanistic approaches for predicting the onset of the critical period during thaw, load restriction durations, and the allowable loads on pavements. This paper reviews the current state of the art in pavement evaluation in cold regions.

This paper continues to document the long-term street reconstruction program in Duluth, Minnesota as previously described in a paper published in 1998 by some of the same authors. The program started in 1993, construction started in 1994. At the completion of the 2001 construction season, 38.5 miles of road have been reconstructed. The 2002 program provides for the reconstruction of an additional 6 miles of road. This program is slated to continue until all 355 miles of city streets have been reconstructed. This paper will discuss the performance of streets in place, expected life cycle costs, current roadway sections, and future modifications to the program.

Although major highways are designed to withstand high volumes of traffic year round, low volume roads are highly susceptible to damage from trafficking during spring thaw. To reduce pavement damage, states, counties, and Federal agencies often post load restriction signs. However, companies whose livelihood depends on trucking can suffer major economic losses while waiting for thawing roads to recover and load restriction signs to be removed. Additionally, restriction-exempt vehicles, e.g., snowplow, fuel, and garbage trucks, can cause damage on closed, roads during spring thaw. Pavement damage can be particularly severe in regions with multiple freeze-thaw cycles. Similar damage occurs in non-frost climates during wet seasons. The US Department of Agriculture Forest Service has conducted extensive studies showing significant benefits are derived from using trucks with reduced tire pressures on gravel- and non-surfaced roads: Aggregate design thickness can be reduced by up to 50%, reduced rutting results in reduced required maintenance/grading, erosion can be reduced by up to 84%, tire life is increased, and a smoother vehicle ride results in reduced driver injury and fewer vehicle repairs. The Forest Engineering Research Institute of Canada and other agencies have conducted further studies, all of which show appreciable reduction in road damage by using reduced tire pressure. In seasonal frost areas, road maintenance agencies can either shorten the length of the seasonal road closure by allowing lower tire pressure vehicles to resume hauling before full recovery is achieved (yet produce no more damage than on a fully recovered road with conventional tire pressures) or shorten the road closure season even more by allowing hauling with reduced tire pressure to yield an acceptable level of damage. This paper provides a non-technical discussion of several tire pressure studies, the results of which can be used to develop an alternate road usage technique to optimize the balance between reducing road damage and maximizing truck-dependent local economies, particularly in seasonal frost areas.

The essential question in the rehabilitation procedure of the roads is how to find the right activities on a certain road section so that the quality of the service and the life cycle costs are on right level. Pavement management system has proved to be a valuable tool on network level. On project level we have good tools for investigating and analysing the condition state of the roads. The tools for choosing and dimensioning different rehabilitation methods are not yet ready. A lot of development work is going on and is still needed. This paper describes the investigation and repair methods that are already in use. Because the theories are still "open" on many areas so many of the notes are based on the experience the author has gained during the 14 years of working with pavement design.

The Yukon River Bridge in interior Alaska is recognized as an outstanding civil engineering design. The structure is a six-span 884.4-m steel bridge on a 6 percent grade. Two 155.9-cm wide by 414.0-cm deep steel box girders support an orthotropic steel deck. The structure carries the oil pipeline, vehicles, tourism busses and heavy trucks. In addition to highway traffic and the oil pipeline, there is potential for the structure to carry a future gas line. Weather can vary from harsh winter temperatures combined with snow and ice to mild summer temperatures. This structure was designed in the early 70's with a temporary 127-mm two-layer timber deck-wearing surface. Since then, timber running planks have been replaced three times with similar timbers (1981, 1992, and 1999). In 1992, in addition to running planks, timber deck planks were replaced and the steel deck was cleaned and coated against corrosion. A successful wearing surface for this bridge must be cost effective, lightweight, abrasion resistant and provide traction; especially during winter months. A wearing surface selection criterion is discussed and wearing surfaces on similar bridges are examined. Two examples illustrate a design procedure for selecting a wearing surface on this structure; design charts are used. The design charts account for truckloads and temperature change. No charts are available for traction or abrasion.

For almost twenty years, road access between the Kuparuk oil field and the infrastructure at Prudhoe Bay/Deadhorse, Alaska was disrupted for an average of 6 weeks during spring flooding of the Kuparuk River. Although a permanent crossing was constructed across the Central Channel in 1981, the East and West Channel roadways were breached annually to allow passage of spring break-up flood waters. In 1999, permanent structures were constructed across the East and West Channels, providing access year-round, except for a maximum closure of one week during spring break-up. The innovative design of the east and west channel crossings involved a combination of low water roadways and submersible bridge designs. With this design, large spring floods are allowed to pass over low water roadways in all three channels and over the east and west channel bridges during extreme spring flood events. Since construction, the East and West Channel Crossings have experienced two break-up floods. This paper will discuss the observations and performance of the Kuparuk River Crossings during the 2000 and 2001 spring break-up floods and provide recommendations for future designs of similar crossings.

This paper will give an overview of imaginative steel deck bridges currently in operation in cold regions throughout the world as an aid in the "type selection" process.. Imaginative bridges from Canada, Norway, Russia, Sweden, Ukraine and the USA were selected to demonstrate the complete range of steel bridges such as movable bridges; suspension bridges, cable stayed bridges, box girder bridges, railroad bridges, pipeline bridges and floating bridges. The advantages of steel deck bridges in cold regions will be summarized. The names of the owners, designers, fabricators, and contractors have been included to credit their success and contacts to discuss details beyond the scope of this paper. A list of 25 references is provided.

Recent innovations in bridge abutment design have resulted in the development of open cell sheet pile bridge abutments. The open cell abutment structure is a cellular flat sheet pile structure driven in a partial circular shape when viewed from above. Open cell structures can easily resist very heavy loads such as extremely heavy drill rig vehicles and module loads, ice attack from arctic river breakup events and high seismic accelerations. Additionally, these abutments uniquely protect the bridge structure from the effects of extreme river scour. These abutment structures are easily constructed without the use of field welding, bolted connections or an independent tieback system, making them less expensive and easier to construct. The system functions as a membrane, relying solely on the resistance developed between the soil and the sheet pile tail wall. The system does not rely on toe embedment for stability. These structures have significant advantages over typical spill through or reinforced earth abutment structures, especially in arctic conditions. Over one-hundred open cell sheet pile structures (fifty-nine, of which are bridge abutments) have been built throughout Alaska and the rest of the United States, some in very active seismic zones. These structures have performed flawlessly in the twenty years of their history resisting hundreds of earthquakes. Details of seismic performance will be presented. This paper reviews the general theory, adaptability, construction, and seismic and ice load resistance of the open cell sheet pile abutment design. Examples and history of constructed open cell sheet pile abutments for heavy duty private installations and for public transportation systems will be presented.

Since bullet train operation started between Tokyo and Shin-Osaka (the Tokaido Shinkansen line) in 1964, Shinkansen trains have been damaged by snow while running at high speed every winter. Although water has been sprinkled over the track and speed control has been implemented to prevent snow on the track from flying up when trains run, these measures have not been completely. In this study, we reproduced a snow-flying phenomenon by implementing model tests to investigate the relationship between the density and water content of the snow cover. Appropriate speed limits were proposed based on the test results. It is planned to construct a Shinkansen network throughout Japan. In the present constrained economic situation, it is necessary for Shinkansen lines to be extended to snowy areas to reduce the costs of construction and snow control measures. Aiming at the reduction of running cost for snow control measures, we designed a viaduct for the Hokuriku Shinkansen line that is planned in Hokuriku region, one of the most snowy areas in Japan. In this paper, we describe the concept of the viaduct and demonstrate its effectiveness as a measure against snow through tests with a full-scale mockup and a motorcar rotary.

The permafrost region is sensitive to all engineering activities such as road pavement or railway construction, since any disturb of its original state will cause instability of the thermal and mechanical state of frozen ground. The staged construction process has been proved to have significant influence on the formation of thermal state of roadbed on permafrost. Usually the cuts suffer more from the thermal state change in service time, in this case the thermal regime variation become a dominating influencing factor for roadbed stability. For this reason in this paper the temperature state considering the construction process was studied for the Berrkakit-Tammot-Yakutsk railway, which was constructed on permafrost in east Russia. A typical cut-and-fill section of roadbed on permafrost was selected for numerical simulation to study its thermal regime formation, on which the running stability of roadbed is directly related. The staged construction of roadbed was modeled. A computer program was created for the mentioned problem. The innovative feature is that the construction process including the cutting and filling work were both taken into account. The real construction sequence was adopted as input parameter in the numerical modeling for mesh producing and its subsequent correction. The computed results show realistic temperature distribution.

This paper presents experimental design and construction data for new methods of strengthening railroad embankments on very icy permafrost soils. Most of these methods are based on adjusting the ratio of cooling and warming factors to reduce the average annual soil temperature and to preserve the original soils' permanently frozen state. One method includes preventive removal of very icy masses from the permanently frozen base, and then refilling the cavities formed with a high consistency soil.

This paper presents a seismic evaluation of the University of Alaska Anchorage (UAA) Engineering Building (UAAEB). The building was designed and constructed in 1981 to the 1979 Uniform Building Code using moment resisting space frames. The evaluation was performed using current design practice following the 2000 IBC and FEMA 273 requirements. A dynamic time history analysis was performed using a synthesized earthquake record based on the M_w 9.2 "Great Alaska Earthquake of 1964". Strong shaking exceeded 90 seconds, with felt motion lasting for over 4 minutes. Anchorage suffered significant damage due to the event. The peak horizontal ground acceleration on bedrock was estimated at 0.218g. Extensive development has occurred in this area of Anchorage since 1964, including the UAA Campus, and nearby, the Alaska Native Medical Center, and Providence Alaska Medical Center. Geotectnical investigations have identified the UAA Campus as highly susceptible to amplified seismic ground motions on the order of 2.5 or higher. A thorough investigation of the building was conducted using the 2000 Edition of International Building Code (ICC 2000); FEMA-273 (FEMA 1997 a). "NEHRP Guidelines for the Seismic Rehabilitation of Buildings"; and FEMA 310, "Handbook for the Seismic Evaluation of Buildings — A Pre-Standard." Pushover analysis studies identified elements of the structure critical to reducing damage. These critical elements were identified for seismic retrofit.

Alaska is one of the most seismically active areas in North America. Large-scale seismic event occurrence is more than ten times greater than in California. Approximately 40–50% of the communities with 60% of the total population are located in seismic zones 3 and 4, which are areas with the potential for high seismic risk. Due to limited access and the isolated locations of many of these communities, a much greater reliance is placed on many of the essential, lifeline facilities. In addition, a much higher per capita investment exists in the facilities, and any recovery effort or needed repairs are expected to be delayed, should wide spread damage occur. Extended periods of snow cover in Alaska increase the likelihood of coincident large snow loads with a seismic event. A recent trend in earthquake engineering of lifeline facilities is to design structures to a higher and more realistic level of performance. This concept grew out of the extremely large capital expenditures required to restore infrastructure after recent earthquakes in Northridge, California; Kobe, Japan; Turkey; and Greece. Application of advanced dynamic analysis methods has been limited to high cost, large structures. The availability of software for personal computers allows performance based analysis and design of lifeline structures for lower cost projects in small communities. An example of this approach is used to evaluate the performance and response of a ground level steel water storage tank both with and without snow loads to determine whether a significant effect results. A synthetic time history of the horizontal and vertical components of the 1964 Alaska Earthquake is used in the analysis. The computer program ANSYS is used for the finite element analysis (FEA) of the tank and contained fluid. Results are then compared with code values.

Remote Monitoring of environmental conditions has become an increasingly popular means of data collection in part due to the advancements of wireless communication equipment. Recently, remote monitoring stations have been used to collect snowpack and weather data, and to detect avalanches along transportation corridors and other areas of interest. The use of remote monitoring stations in major slide paths have helped transportation maintenance crews predict snow stability, determine when to perform avalanche control activities, and detect when a slide has occurred. Certain data collection activities require placement of sensors mounted on a monitoring tower, including Doppler radar, directly in or near the avalanche slide path. This will, in some cases, subject the tower to dynamic avalanche forces, snowpack creep forces, as well as other adverse conditions typical of mountainous terrain of cold weather regions. The design of a monitoring tower to resist these forces presents several engineering challenges. This paper reviews some of the advances in avalanche prediction and detection, and examines the dynamic response of a monitoring tower due to avalanche loading conditions using the Finite Element Analysis approach, including time history analyses. Based on the analysis results, suggestions for future work on avalanche loading and the design criteria of remote monitoring towers are presented. A discussion will be given on the dynamic amplification of the tower system as compared to equivalent static loading, and conclusions will be made on the application of monitoring towers in the cold regions.

Building pressurization, the differential pressure between the interior of a building and its exterior surroundings, is an important design consideration. Pressurization is the driving force in building infiltration/exfiltration. It also affects air flow within building zones. Improper calculation of pressurization can result in undersizing the building's heating and cooling systems, improper operation of air distribution systems, improper operation of elevators, and freezing and failure of water distribution and circulation systems. Building pressurization is affected by several environmental and design considerations. Primary environmental influences are: wind speed/direction and exterior-to-interior temperature difference. Pressurization due to these two parameters is generally referred to as wind effect and buoyancy or stack effect respectively. In extreme cold climates, the predominant effect is of the buoyancy type. This effect is caused by the temperature, and thus air density, differences between the interior of the building and its exterior surroundings. The larger the temperature difference, the larger the buoyancy effect. In extreme cold climates, large temperature differences often occur at times when wind speed is negligible. Also of critical importance is that while wind effect is transitory, lasting from minutes to hours; extreme temperature differences can be persistent, lasting days, weeks, or longer. The American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) presents an idealized equation to calculate the buoyancy effect. This paper compares differential pressure measurements from an actual building to this idealized model. It also presents several new statistical models based on the collected data. These new models should provide engineers with improved tools to properly account for building pressurization for designs in extreme cold climates.

Cold weather inhibits construction productivity in the northern tier of the United States. Over the years the U.S. Army Engineer Research and Development Center's Cold Regions Research and Engineering Laboratory (CRREL) has developed formulations for cold-weather concrete that facilitate economical placement of concrete at mix temperatures well below freezing. Like many other technological advances, the commercialization of this technology has effectively been blocked by a lack of standards. CRREL is working with several State Transportation Departments to develop a near-term cold-weather concreting capability using off-the-shelf technology. Paralleling this effort, the Civil Engineering Research Foundation is spearheading an initiative to develop an acceptance standard for low-temperature admixtures. The world of cold-weather concreting promises to become a bit friendlier within the next few years and beyond.

A large townhome complex north of Duluth, Minnesota experienced frost related problems during construction. The building distortions continued to increase after construction and the damage reached the point that some of the structures had to be removed from service. Geotechnical and Structural investigations showed highly frost susceptible soils, poor drainage and poor workmanship during construction as well as design deficiencies that affected performance. The investigative work included dismantling some of the more distorted structures. The eventual repairs were massive and included replacement of foundations, replacement of slabs, foundation insulation and installation of drainage systems. The repairs were complicated by most of the building being occupied. This technical paper will document the project history; the studies carried out prior to remedial designs, the repair designs considered, subsurface exploration, exposure of the existing foundation system, laboratory testing soil samples, thermal analysis of the existing foundation system, structural analysis of the existing foundation system, alternate designs for foundation repairs and the significant reconstruction effort.

Helical piers have been used as foundations for board walks, utilidors and fences in rural Alaska in cold and warm permafrost. The piers are becoming more and more popular due to their light-weight, ease of transportation and installation, and resistance against pile jacking. However, engineers have been hesitant to specify them as foundations for buildings due to the lack of design guidelines for frozen ground. To increase the use of helical piers as cost effective foundation alternative, Alaska Science and Technology Foundation funded a study to create these guidelines. This paper presents the development of a finite element model for helical piers in frozen ground and an example of design of helical piers in frozen silt.

This paper provides a brief discussion of design and construction considerations for small boat harbors in cold regions. Information is offered in general terms and it is left to project engineers to develop appropriate design practices for their respective projects. The paper avoids giving general float design information, which has been exhaustively covered in other reference sources. Rather, the paper focuses on the main design considerations inherent with harbors in cold regions. These main considerations include: 1) Types of float systems, 2) Horizontal and vertical ice loading on structures and icing inside harbors, 3) Cold climate effects on utility design, and 4) Seasonal construction considerations.

Port engineering brings together many traditional specialties of civil engineering. Difficulties related to freezing temperatures, snow accumulation, and extended darkness compound the challenges of geotechnical, structural, architectural, mechanical, electrical, transportation, and coastal engineering in designing and operating sea and river ports. Previous guidance on cold regions aspects of port engineering has appeared in scattered conference papers and subdivisions of a few general port engineering references. The ASCE Technical Council on Cold Regions Engineering has initiated compilation of a monograph on cold regions port engineering. This paper highlights aspects of cold regions port engineering to be discussed in more detail in the completed monograph. Priorities for future research and development are discussed in light of growing pressures worldwide to develop and export by sea mineral resources of the far north.

The paper describes the design, fabrication and installation of a novel platform in Cook Inlet, Alaska. By using engineering creativity and thinking "outside the box" the platform project was completed by Forest Oil Corporation, an independent oil company, at a fraction of the cost of a conventional platform, thereby allowing exploration and subsequent development of a hitherto non-commercial oil field discovery dating back to 1969.

The combined effect of seawater and freeze-thaw action on the pore structure and degree of saturation of small mortar specimens (φ 1 x 2 cm and φ 0.5 x 1 cm) is investigated. The results show that the cement paste becomes porous under the influence of seawater, leading to an increase in the degree of saturation. Seawater immersion and freeze-thaw action leads to the enlargement of pores with radii in the range 10² to 10³ nm, with subsequent occurrence of micro-cracks. As a result, the degree of saturation rises rapidly until the mortar is destroyed.

The coast of Alaska has received major attention for mapping during the last decade. Increased efforts to promote safe navigation through improved nautical charts; map coastal habitats for endangered species and essential fish habitats; land new seabed fiber optic cable systems; and develop port, harbor, and resource extraction infrastructure are all requiring improved cartographic products. Alaska's vastness and remoteness are depending on traditional, new, and emerging technologies to gather the surveying data upon which such projects depend. Horizontal and vertical control has improved through the use of GPS technologies, methodologies, and algorithms. Tidal zoning transfers this control to offshore waters and remote coastal areas, establishing datums for both mean lower low water and mean high water, as required by NOAA and USGS respectively. From this common point, technologies are profiling the land or seabed to comparable degrees of precision and cartographic definition. Photogrammetric technologies, including the use of Side Looking Aperture Radar (SLAR), coupled with interferometry, are defining coastal uplands to new levels of precision, regardless of land cover. Air and space borne Synthetic Aperture Radar is defining coastal lands and land-ocean processes, and river and sea ice parameters, allowing meter resolution that can be tide coordinated regardless of cloud cover. Light Direction and Ranging (Lidar), in an airborne configuration, is bridging the land sea interface, allowing airborne measurement of uplands, shoreline, and nearshore bathymetry at new levels of efficiency. The swath of land and near shore imaging couples with multi-beam echo sounder systems (MBES) producing accurate 3 dimensional cartographic products portraying the coastal bathymetry and extending off the continental shelf. Together, mapping accuracies are being obtained to the submeter level via remote sensing tools.

A depth-averaged, hybrid Lagrangian-Eulerian model for ice interaction is described, and used to evaluate ice loads on a 10m-wide, cylindrical pier. Additionally, results previously calculated using a discrete element model, and those from analytical formulas commonly used to estimate ice forces, were compared with the full-scale data. The comparisons are conducted in order to verify the results of these different types of approaches for calculating ice loads. There was good agreement between field observations from similar structures and the hybrid model's calculated values. The results obtained using the discrete element model also compared favourably to full-scale data. In contrast, forces estimated from analytical formulas were much higher than those from the field measurements.

Preferential natural convection heat transfer in highly-permeable rock embankments and pads is a technique which can be used to generate a passive cooling effect. Such an effect is usually desirable in permafrost areas in order to counteract the warming influence that often accompanies construction activity. Left unchecked, this warming may result in permafrost thaw and failure of the foundation due to of thaw settlement. In non-permafrost areas convective cooling in rock layers and embankments can lead to problems with frost heave due to enhanced winter-time cooling. The current work discusses the characteristics of these rock layers, including techniques for predicting the thermal and fluid mechanical properties. Sample applications are described and experimental and numerical results are discussed.

Thermosyphons have been used to maintain permafrost below structures for over forty years. The Chena Hot Springs Road Test Section became operational during the fall of 1998 and includes three test sections underlain with different types of thermosyphons plus a control section. The test section overlays high-moisture-content permafrost. After two seasons, the thaw depth decreased and the freezing depth increased in all sections, including the control. Pavement edge temperatures showed a decided cooling trend which was slight for the control, more pronounced for the UAF/CRREL units and AFI flat loop evaporator units, and highest for the AFI buried units section. The centerline thermal conditions relate to the condenser size, while the pavement edge or shoulder conditions relate to the type of installation. During the winter season, the AFI buried condenser thermosyphons show surface warming and sublimation of snow closer to that of the control section, while the other two test sections are colder at the surface during the winter season.

Thermosyphons have been used to provide passive subgrade refrigeration for structures founded at-grade on permafrost for approximately 25 years. The majority of these structures utilize thermosyphons installed with conventional sloping evaporators (CSE) beneath subgrade insulation. In the last 5 years, the use of thermosyphons with flat loop-type evaporators (FLE) has been introduced for providing subgrade cooling. FLE units offer versatility for design and their use can simplify construction when compared to installation of CSE thermosyphons. Performance tests show FLE units offer increased heat transfer compared to CSE thermosyphons when installed at windy sites. Advantages and design of subgrade cooling systems using both CSE and FLE thermosyphons are discussed. Critical elements to be considered in the design of either system are listed and a matrix is offered to assist the designer when choosing a thermosyphon system for subgrade cooling. Hybrid thermosyphons, buried condenser thermosyphons, flat evaporator thermosyphons, and flexible evaporator thermosyphons are also discussed along with their potential applications.

The Tube Suction Test (TST) was developed in a cooperative effort between the Finnish National Road Administration and the Texas Transportation Institute (TTI) for assessing the moisture susceptibility of aggregate base materials. The moisture susceptibility ranking is based on the mean surface dielectric value of compacted specimens after a 10-day capillary soak, where the dielectric value is most sensitive to the amount of unbound water that exists within the aggregate matrix. The purpose of this research was to investigate the relationship between the final dielectric value in the TST and the frost susceptibility of aggregates. The laboratory test program included 35 specimens representing 10 aggregate base materials from Indiana, Minnesota, Pennsylvania, Texas, and Virginia. Each sample was subjected to the TST and afterwards to a frost heave test developed at TTI. In the TST, electrical conductivity measurements were also made to evaluate the salinity of the specimens. Sample volumetrics were computed and compared for post-TST and post-freezing conditions. In this study, aggregates classified in the TST as good performers did not experience significant frost heave, while several materials with higher dielectric values exhibited substantial amounts of heave. These latter specimens were characterized, on average, by greater percentages of fines, higher porosity, and higher moisture contents in the TST. Aggregate samples with high salinity also had high dielectric values in the TST, but they were generally less frost susceptible than other high-dielectric specimens due to the depression of the freezing point caused by salt ions in the pore water. Samples with high porosity also exhibited reduced frost heave because the additional internal space allowed formation of ice with less expansion of the aggregate matrix.

In-situ frost heave test was conducted for the three kinds of soil in open pits. The purpose of this experiment was to observe frost heave of geotechnical materials in natural conditions and to provide fundamental data for future forecasting frost heave at cut slope and road fills. The experiment of the first season showed the following. (1)The maximum frost penetration depth varied by soil type. The soil which has low thermal conductivity showed small frost penetration. (2)The measured frost heave did not clearly reflect the frost heaving properties in the laboratory frost heave test. Although this might have been due to the difference in saturation, ground water supply and other conditions, further examination will be necessary to clarify this point. (3)The maximum frost heaving force of 3 to 5 MPa was measured. This was thought to serve as a reference in considering future measures against frost heaving.

Behavior of both rock glaciers and conventional glaciers is highly affected by the character and temperature of their bottom deforming layer, usually composed of a mixture of ice and rock elements, the latter ranging from silty sand up to large boulders. Similarly as in the rock mass mechanics, large scale behavior of such mixtures is difficult to evaluate either by direct in-situ measurements or by taking samples. This paper uses some known rock mechanics principles to simulate the large-scale behavior of such mixtures, by considering the role and interaction of each element in the mass.

Consideration of freezing and thawing air temperatures on foundations, pavements, utilities and structures is integral to civil engineering projects in cold regions. Air-freeze and thaw indices are commonly used to characterize the combined variation, magnitude and duration of annual temperature cycles. Design air temperature indices are typically defined to represent more extreme warm-summer and cold-winter seasons. However, there are situations where a design `cold-winter' freeze index is of little value; e.g. in permafrost regions when the stability and performance of embankments and foundations dependants upon some magnitude of cooling each winter to re-freeze the seasonal active layer and/or lower the subgrade temperature. For these cases it would be more critical to evaluate the thermal consequences of a `warm' winter; e.g. reduced bearing capacity and increased creep. Presented herein are design warm-winter freeze indices, as well as updated cold-winter freeze and warm-summer thaw indices for eleven Alaska communities based on daily climate records from 1971 to 2001 including Anchorage, Barrow, Bethel, Bettles, Central, Fairbanks, Gulkana, Kotzebue, Nome, Northway and Tanana; all but the first located in regions underlain by permafrost.

A probabilistic approach may be adopted to predict freeze and thaw depths to account for the variability of (1) material properties, and (2) contemporary and future surface energy input parameters (e.g. air temperatures, cloud cover, snow cover) predicted with global climate models. To illustrate the probabilistic approach, an example of the prediction of thaw depths in Fairbanks, Alaska, is considered. More specifically, the Stefan equation is used together with the Monte Carlo simulation technique to make a probabilistic prediction of thaw penetration. The simulation results indicate that the variability in material properties, surface energy input parameters, and temperature data can lead to significant uncertainty in predicting thaw penetration.

Year-round studies of the geothermal impacts of road construction in a "warm" (–1 to –2°C) permafrost area were undertaken during 1954–1962 at six road sections across the Richardson and Glenn Highways, in the vicinity of Glennallen, Alaska. The most extensive studies were at Richardson Highway Mile 130 where nine 6.1-m vertical thermistor cables were installed beneath the newly constructed road, beneath a 40-year-old roadway, and in undisturbed areas. The cables, installed beneath the centerlines, shoulders, and the adjacent ditches of the highways, as well as beneath undisturbed areas, provided weekly temperature measurements at 13 depths. A tenth cable, with thermistors at 0.3-m spacing, was installed horizontally at a depth of 1.2-m across the new road. The mean annual ground temperatures in the ice-rich lacustrine silty clays in the Glennallen area appeared to approximate –1.2°C, about 1.8°C warmer than the mean annual air temperatures. The seasonal amplitudes of temperature changes were greatest beneath the centerline of the new road; increasing the depth of seasonal thaw from 1.87 m, versus about 0.7 m in the undisturbed areas, in 1954 to 3.0 m in 1957. The old road centerline and ditch then had similar depths of thaw, about 4.9 m, after almost 40 years of light usage. This suggests that differential settlement in the new roadway would continue until at least an additional 1.8-m-depth of thaw had been completed. While the permafrost at the 6.1-m depth beneath the centerline of the new road was warming, the permafrost at the same depth beneath the old, abandoned road was cooling slightly during the study period.

The authors have been studying shore erosion in Russian Arctic since 1973. Numerous monitoring sites have been established at sea, river, and lake shores in Russian Arctic. Different methods of evaluating the rate of erosion have been tested. Two of these methods, monitoring along stationary transects and comparison of aerial photographs of reasonable scales taken at different times, were found to be most productive. Data of shore erosion monitoring from a few to more than 30 years are presented.

Recent advances in de-icing and anti-icing technologies have been evaluated in the laboratory and field to assess their applicability for use at hydraulic (navigational and hydroelectric) structures operated by the U.S. Army Corps of Engineers. In addition to innovative heat panel designs, the U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) has evaluated low-adhesion paints and coatings and electrolytic and electro-expulsive shedding (EES) technologies. Comparisons of engineered low-adhesion coatings to standard paints used by the Corps show that little improvement is gained for some coatings while for others gains of nearly 50% can be realized. Plastic materials (used as cladding) offer a slight advantage over coatings in terms of their ability to reduce ice adhesion strength. The energy requirements for electrolytic and electro-expulsive shedding are as much as 50 times less than heat tracing. However, corrosion of the electrodes using electrolytic methods can be substantial. Electro-expulsive shedding technology is being used on aircraft for in-flight deicing and shows promise for use on hydraulic structures as well.

In cold climates, atmospheric icing is an important factor for the design and reliability of overhead transmission lines. For strength and reliability assessments, a data base is necessary to characterize the statistics of mechanical and meteorological conditions during accretion. Since the early 1980's, a natural icing test site located on Mt. Valin (Quebec), Canada, has been used to record such icing data. This paper presents results, with respect to the accretion phase, obtained from our analysis of this extensive database. The four types of ice defined were rime, glaze, wet snow and mixtures of these types. A total of one hundred and three icing events were selected on each of the four cables located at the test site. Forty-eight events produced rime, thirty-six produced glaze, six produced wet snow and thirteen produced mixtures of these types of ice. We then analyzed the distributions of the icing rate, the air temperature and the wind speed. By comparing the main test line and the perpendicular second test line (which is oriented along the prevailing wind direction) icing rates were found to be significantly lower in the latter case. This result indicates that for all types of ice accretion the cable orientation is an important factor on the accretion properties. The study of the icing rate distributions suggest that the normal probability law does not estimate high icing rates well. Other probability models that should be further investigated are the Weibull, gamma, beta and exponential distributions.

Ice loads were measured for ten years on the east pier of the NY Route 37 bridge over the St. Regis River in Hogansburg, NY. This record comprises the longest documented history of ice loads on any bridge in the world. Statistics on the loads for the 10-year period of record are presented along with statistics on ice thickness and strength. The measured ice strength at this site agrees well with other data measured in Canada and Europe. The largest measured ice force on the pier was 356 kN, which is only 15% of the design ice load. Statistical analysis of the data indicates that the return interval on the design load appears to be greater than 1000 years, suggesting the design may be overly conservative. Probabilistic approaches to determining the appropriate design load may help prevent overdesign of future bridges, thereby reducing cost while still maintaining a reliable transportation infrastructure. Field measurements of ice loads on a wide range of river sizes extending over many years will be required to use probabilistic approaches with reasonable levels of uncertainty.

A demonstration of the effectiveness of dusting for advancing the deterioration of river ice was carried out on the Red River of the North Basin shared by Minnesota and North Dakota. A sand spreader suspended beneath a helicopter was used to apply sand on the ice. The ice strength and thickness was monitored in dusted and control areas at five sites over a three-week period from the time of dusting to ice breakup. These tests showed no increased deterioration in terms of reduced ice strength or thickness in the dusted ice in comparison to the undusted ice. The failure of the dusting to produce any effect on ice deterioration is attributed to the sustained subfreezing air temperatures experienced throughout the test period and the light color of the sand used for dusting.

The effect of an ice cover on the rate of erosion and deposition of riverbed sediments has been the subject of much speculation. At the center of the debate is the lack of field measurements correlating the hydraulic and ice conditions with changes in bed elevation. With the recent development of robust scour probes using time-domain reflectometry (TDR) technology, it is now possible to obtain field measurements that are independent of surface conditions. Arrays of TDR probes were installed at three sites to monitor the bed elevation from freeze-up through break-up. The sites were in the Missouri River in eastern Montana, in a navigation pool on the Mississippi River, and upstream of a bridge pier in the White River in Vermont. The probes were connected to a data acquisition system to monitor the scour-fill cycle in real time during the winter, along with temperatures and water pressure. Measurements from the three sites imply that the rate of erosion or deposition of bed material depends on the variation in flow from the discharge at the time the ice cover formed.

The Baltimore District of the U.S. Army Corps of Engineers recently undertook a study to determine whether a change in the operation of one of its flood control reservoirs would affect the degree of flood protection downstream. The intended operational change entails eliminating the current practice of providing an additional winter drawdown, which provides increased flood control storage for winter and spring runoff. The study indicated that the proposed change would not affect the current level of flood control downstream of the reservoir. Questions remained as to whether the ice regime would be changed and flooding increased near the upstream end of the reservoir. The paper describes the analysis used to determine the effects of the reservoir operational changes on the ice regime.

River ice periodically impedes winter tow traffic on the major inland waterways in the U.S. During ice periods, moving vessels continually re-break the ice cover on the navigation channel creating an accumulation of broken ice pieces known as brash ice. In the pools above navigation dams where water velocity is typically low, brash ice congestion may become severe enough to bring tow traffic to a standstill. This nearly occurred in January of 2001 on the upper Ohio and Monongahela Rivers where the Pittsburgh District of the US Army Corps of Engineers operates a series of 15 locks and dams. In response, the towing industry asked the Corps about the possibility of releasing extra water at dams to clear brash ice downstream. At the district's request, the Cold Regions Research and Engineering Laboratory (CRREL) studied the problem in an effort to determine what flow levels and durations would be needed and to clear brash ice from the pools under a variety of scenarios. Based on observation and theory, CRREL developed relationships between discharge, time and brash ice volume cleared from the navigation channels above each gated dam in the Pittsburgh District.

Frigid winters, severe ice conditions, and dramatic spring floods exact a yearly toll on dams and hydraulic infrastructure. Inflatable gates or "rubber dams" are a non-rigid water control alternative that can provide significant benefits in cold regions. This relatively recent technology can be successfully employed at both new and existing water retaining structures. Inflatable crest gates were installed to replace traditional flashboards at a Mississippi River power and navigation dam. This paper discusses the motivations for improved crest gate technology, economic justification for inflatable gates, installation procedures, and system performance to date.

Rainfall frequency information is the essential input for many water resources evaluation projects such as stormwater management, transportation drainage and urban hydrology. The last general study of rainfall intensity-duration-frequency (IDF) information for Alaska was completed in 1963. The last published IDF curve set for Fairbanks was in 1955. Since rainfall storm characteristics may vary over time, an updated rainfall IDF model will be a useful input tool for water resources studies in interior Alaska. As part of a stormwater management study with the City of Fairbanks to map and model the stormwater drainage system in the downtown area, we performed a rainfall frequency study using 37 years of data from 1950 to 1999. (There are several missing years in this series.) We assembled a partial duration series of the 45 highest independent events with 1 to 24 hour durations and 1.5 to 50 year return periods. The return period was estimated using the Blom Equation. The 5, 10, 15, and 30-minute durations were estimated by calculations from the 1-hour value. Following the standard conversion from depth to intensity values, the IDF relationships are shown in both table and graphical form and may be easily used in standard stormwater runoff calculation programs. In comparing the intensity values from this study, we found a decrease to about 60% of that from the 1963 value for the 50-year return period and 5-hour duration storm. In other combinations we found similar decreases. Since this type of analysis can be accomplished with data that is readily available and easily downloaded from Internet sites, we recommend that similar calculations be performed for other Alaskan cities and used in place of the older 1963 study.

This joint government-university stormwater management development project will eventually aid in compliance with Phase II National Pollution Discharge Elimination System (NPDES) requirements. The project is enabling the inventory and initial modeling and investigation of management techniques for the stormwater drainage system of the interior Alaskan city of Fairbanks. The City of Fairbanks is the lead agency and end user of this project and is primarily coordinating, mapping and inventorying their stormwater system. The Civil and Environmental Engineering Department at the University of Alaska Fairbanks (UAF) is using the information gathered by the City to model the system. The hydraulic model created will be a comprehensive tool required for understanding the system and is a necessary foundation for continued development of a stormwater management program. Data is also being collected for eventual support of a water quality component to the model. Ancillary to this data collection, jet truck cleaning, the primary means of system maintenance, is being investigated for its potential as a water quality management technique.

By estimating the groundwater flow drained by rivers, it was established that most hydrographs of the cold period are essentially deformed. The reason for the deviation of the actual hydrograph from a true one is that liquid flow is partially or entirely due to the formation of river icing. Such withdrawal of flow distorts significantly the seasonal and long-term dynamics of natural resources of subsurface water, and this especially applies for water of high frequency (for example 95%), thereby impairing the reliability of hydrogeological forecasts. With the purpose of compensating for the influence of icing regulation, a method of reconstructing the hydrograph of a cold period is suggested.

The initial state of Irkutsk groundwater has been studied in connection with the reconstruction and extension of the municipal wastewater treatment plant, in the vicinity of which there are dumps of solid domestic waste and snow. Pollution sources are located on the surface of the right-bank high flood plain of the Angara River valley. It was ascertained that excessive leakages and infiltration feed under the municipal wastewater treatment plant and dumps leds to the formation of a hydrogeodynamic domes of brackish water with anomalously high content of NH₄, Mn, Fe, Cl and other components of chemical composition. Pollutants are carried with the groundwater flow to the Angara River bed, but in significantly lower concentrations as a consequence of intense dilution with pure groundwater. An increase in the capacity of the municipal wastewater treatment plant, with the dumps persisting, will inevitably lead to an enhancement of groundwater contamination. To minimize the potential environmental damage, a package of mitigating measures is proposed.

Landscape structure and numerical cluster analyses were applied to hydrological regionalization of the environment of a constructed gas pipeline in the North of European Russia. The studies are to improve runoff calculation on the rivers along the pipeline route to mitigate the damage caused by spring floods. As a result the basins are determined to be analogues for the numerous ungauged rivers by flood flow calculation. Calculations were performed using adopted manuals with detail evaluation of input variables such as snow water content in those basins located on hilly uplands. Regional correlation between runoff and conditioning factors were obtained and taken into account for the area. A great attention was paid to the development a model for how to take the wetland-related impact on runoff regime of the region.

Snow cover spatial distribution and snow melting have been studied at Valday Hills and in many other regions of Russia. An expert appraisal is proposed of how the snow cover obstructs industrial areas. To improve flood flow forecasts, a correlation has been established between snow cover and terrain elevation. Landscape conditions, forest at first, have been investigated as affecting snow cover distribution. An original method is proposed for quantifying the local scale distribution by the data on relief, land use and forest species. Snow cover distribution is examined as a factor influencing construction engineering. Snow melting processes were explored as conditioned by energy flux. Surface albedo of intact and contaminated snow was determined and appointed to be a key factor in energy exchange. Data of long-term observations were gathered to analyze the time series of snow water content and net water yield from a melting snow pack. Extreme values of snow water content were used as an input for hydrological calculations of drainage flow. Proposals were made of how to renew and improve the observation of snow cover as one of the main components of global climate and environment.

This paper presents an evaluation of capping alternatives for an 18.2 hectare landfill located in Barrow, Alaska. When closure planning for the Barrow Landfill began, excavation and removal or treatment of wastes was included in the initial evaluation of potential closure options. However, due to Barrow's remote location and the high costs of waste excavation, transportation, and/or incineration, capping was identified as the most cost-effective closure method. Three general types of caps were evaluated in a comparative analysis, including a freezeback cap, silt cap, and a composite soil/geomembrane cap. A numerical selection process introduced by Peggs and Thiel was used for rating and selecting a specific geomembrane. Cold weather shear testing results for Linear Low Density Polyethylene (LLDPE) and Polypropylene (PP) are presented. Based on the evaluation process and the cold weather testing of geomembrane samples, the recommended capping alternative was a buried PP geomembrane.

Freezeback landfills, a special regulatory category in Alaska for landfills located on permafrost, are discussed. Since most lands in the Arctic are generally wet, poorly drained, and underlain by ice-saturated permafrost, aboveground landfills are preferred over other types. Design goals for an aboveground freezeback landfill are encapsulation and freezeback. Thermal modeling guides the design for new landfills underlain by permafrost. Fluid management, fill sequence, and corrective action plans are critical to successfully operate a landfill located on permafrost. Because most landfills in the Arctic are small and often expensive to build and operate, achieving complete freezeback by placing a thicker final cover may not be practical or affordable. Instead, designing for partial freezeback may be more appropriate.

This paper describes design considerations associated with the use of a geosynthetic clay liner (GCL) in both the base lining system of a planned new cell and in the final cover of an existing unlined cell at the Central Landfill in Palmer, Alaska. The Cell 2B base lining system will include a composite geosynthetic liner consisting of an 80 mil (2 mm) textured HDPE liner overlying a GCL on both the sideslopes and base of the cell. A similar base lining system has been used successfully at the nearby Anchorage Regional Landfill. The use of this lining system in a Seismic Zone 4 area on relatively steep side slopes requires careful evaluation of both internal shear strength of the GCL and interface friction between the GCL and textured HDPE. Summarized results of shear strength testing performed on several types of GCL at both high and low normal stresses are presented here. Design considerations for use of a GCL in the final cover over unlined Cell 2A at the Central Landfill are also discussed. Requirements for GCL conformance testing and construction quality assurance are briefly described. Examples of GCL use in other Alaska landfills are also referenced.

Soil-bentonite mixtures are often used for liners and covers for waste containment systems in cold regions. In these applications, soil-bentonite mixtures can be exposed to environmental stresses such cycles of freezing and thawing, which can increase the hydraulic conductivity of soil-bentonite mixtures. In this study, hydraulic conductivity tests were conducted to assess how freeze-thaw cycling affects the hydraulic conductivity of a soil-bentonite mixture. The permeating fluids were tap water and fluids containing divalent cations at concentrations representative of naturally occurring field conditions. Results indicate that the hydraulic conductivity of soil-bentonite mixtures can increase by several orders of magnitude as a result of exposure to cycles of freezing and thawing, in the presence of divalent cations. The hydraulic conductivity increase is due to the inability of the bentonite to swell and fill the void spaces in soil-bentonite mixtures. These findings suggest that soil-bentonite mixtures may not be as resistant to damage from freeze-thaw cycling as previously reported by other investigators. Thus, designers and regulators must carefully consider the hydraulic performance of soil-bentonite mixtures in cold regions where they may be exposed to cycles of freezing and thawing.

Hydrogeochemical peculiarities of the processes of the ecologically dangerous waste dumping into the perennially frozen rocks in the Yakutian diamond-bearing province (Western Yakutia) are considered. The expediency of this utilization way applied in the cryolite zone was settled. The results of the simulation of the physical-chemical processes of the brine-enclosing rocks and brine-ground ice interaction are represented. The prospects of high-mineralized solutions burial into the permafrost without negative ecological influence are demonstrated.

Soil Vapor Extraction has proven to be a viable method for reducing the mass of volatile compounds from soils that have been impacted by contamination. The theory, design and use of SVE systems have been fairly well documented, however the use of SVE systems in cold environments such as Alaska has not been adequately investigated to date. This paper examines the use of SVE systems in cold environments. The affect of low soil temperatures on volatile compound removal by SVE is discussed. Methods used to overcome the impact low temperatures have on the operation and effectiveness of SVE systems are examined in detail. Possible low cost strategies such as barometric pumping during winter months are presented as solutions to reducing SVE operating costs in cold regions.

This research was conducted to detect and understand anaerobic degradation of benzene in a sub-arctic aquifer environment. The major point in this paper is that indigenous microorganisms from anaerobic groundwater wells contaminated with BTEX (benzene, toluene, ethylbenzenes, xylenes) can use benzene as a carbon or energy source under conditions favoring iron reduction. Microcosms were prepared and incubated under anaerobic conditions, with hematite (Fe₂O₃) added to some to permit growth of iron reducing bacteria. Several concentrations of benzene were used as a substrate, and the microcosms were incubated at temperatures of 21 °C and 4 °C. Results indicated that the aromatic hydrocarbon, benzene, was anaerobically transformed under both psychrophilic (4 °C) and mesophilic (21 °C) conditions. The temperature and substrate concentration played a role in determining the rate at which benzene was biodegraded under conditions favorable to iron-reducing bacteria. For example, under conditions favoring iron-reducing bacteria, benzene biodegraded faster at 21 °C than at 4 °C in most microcosms during the first two months. Benzene degradation slowed when the concentration of benzene became less than 7 ppb under all conditions. Phenol and propionic acid were detected as intermediates for this transformation.

A release incident introduced 2,380 L (630 gal) of diesel fuel into frozen alluvial soils within the floodplain of the Tanana River, in interior Alaska. The winter release occurred in a residential community, with potential to impact drinking water wells. Mitigation of the problem was confounded by snow cover, proximity to a site structure, and shallow groundwater. Understanding spill dynamics in the subsurface is important toward spill response, assessing impact, and minimizing property devaluation. Two questions needed answering for this investigation: 1) Was 2,380 L (630 gal) of diesel fuel really released? and 2) What is the magnitude of groundwater impact? The spill zone is documented, with focus on the partially frozen active layer. Two approaches to answering the investigative questions are discussed, with emphasis on a mass-balance evaluation of the unsaturated zone. Soil parameters are evaluated for impact analysis of the vadose zone. Soil microstructure is briefly discussed relative to translocation and alteration by hydrocarbon contamination. Soil hydraulic properties are briefly discussed relative to gauging groundwater impact. Knowledge of contaminants in freezing ground in furthered.

Disinfection by-products (DBP) are formed by the reaction between dissolved organic carbon (DOC) in water and a disinfectant, usually chlorine. Raw water samples from 17 small water systems in Alaska were used to study disinfection by-product formation. UV absorbance at 254 nanometers (UV 254) served as an excellent predictor of DBP formation potential (DBPFP) for surface waters. UV-254 was combined with other standard methods such as color and DOC to determine the nature of organic matter contributing to DBPs. No other methods showed the strong correlations between UV-254 and DBPFP. DOC, on the other hand, showed only a fair correlation to DBPFP. For each of the 17 Alaska waters studied, the total trihalomethane formation potential (TTHMFP) and haloacetic acid formation potential (HAA5FP) ranged from 37–1200 ug/L. For each source, the TTHMFP and HAA5FP were essentially equal.

At the Ekati^TM diamond mine, located 300 km northeast of Yellowknife, wastewater consisting of sewage from the housing facility, flow from the vehicle washing bay and wastewater from neighbouring worksites was previously collected, treated and discharged into a local lake. The discharge was observed to have negative impacts on the lake which included an increased algae growth and lowered dissolved oxygen levels in the lower portion of the lake as early as 1997. Part of the cause of this impact was believed to be increased phosphorus concentrations in the lake originating from the treated wastewater discharge. There was concern that the increased phosphorus levels may affect downstream lakes, in the form of eutrophication and decreased winter dissolved oxygen concentrations. To minimize the impact, BHP Diamonds Inc. relocated the discharge of treated wastewater to its processed kimberlite containment system. The purpose of this study was to understand the fete of phosphorus in the treated wastewater when added to the processed kimberlite containment area. The study involved conducting laboratory investigations to develop adsorption isotherms for phosphorus on the processed kimberlite. The phosphorus adsorption isotherms can be used to evaluate the fate of phosphate in the processed kimberlite containment area. The effects of parameters such as temperature, coagulant, and flocculent addition were determined. The quantity of phosphorus adsorbed per gram of kimberlite was found to be low. At a pH of 7.0, 0.5 kg of kimberlite is needed to reduce the concentration of phosphorus from 10 mg/L to 0.1 mg/L in a volume of 1L of wastewater (i.e. 0.2 mg phosphorus removed/g of dried kimberlite). Even though the kimberlite adsorption of phosphorus is low, there is more than adequate kimberlite available in the tailings to remove the phosphorus loading when the pH is 7.0.

Adequate levels of dissolved oxygen (DO) in rivers are essential to sustain aquatic life and maintain acceptable water quality. The most critical period for dissolved oxygen deficits is typically assumed to be summer because low flows often coincide with high water temperatures. However, previous research has documented the occurrence of wintertime oxygen deficits in ice-covered rivers. Despite these observations, water quality models neglect the effects of reaeration and deoxygenation at the low temperatures occurring during winter, resulting in uncertain model results for the winter period. This study provided high-temporal-resolution water quality data for an intermittently ice-covered, relatively nutrient-rich river in Vermont. Field data and laboratory studies were performed to evaluate reaeration and deoxygenation coefficients, and microbial diversity was examined. Our field data showed that DO patterns in a small Vermont river are different during ice-covered periods than during open-water periods and that DO levels can be at or above saturation levels for the ice-covered period. In addition, diurnal cycling of DO persists during the ice-covered period and appears to be related to photosynthetically active radiation (PAR) in a manner that suggests that photosynthetic activity may be contributing to reaeration. Microbial communities were found by two independent measures to be different under an ice cover than in open water.

Alaska's North Slope Borough elected to go with vacuum sewer systems for four of the seven communities in which it is installing piped water and sewer. One of these community systems (Point Hope) has been in operation for over two years. These systems are unique in that they are the first systems in Alaska that use total conventional plumbing (instead of vacuum toilets and gray water valves). This paper presents the planning process which led to the decision to install vacuum sewers, generalized design aspects of the Point Hope system, and operating experience accumulated over two years operation at Point Hope.

This paper describes a construction project in Fairbanks, Alaska where new sewer lines and a lift station are to be installed below the water table. Typically, a contractor would dewater the site, excavate, and install the underground facilities, then backfill and compact. However, the discovery of contamination near the project site required a restrictive dewatering permit by the Alaska Department of Environmental Conservation (ADEC). The first attempt to dewater the site was unsuccessful due to abundant summer rain producing a rapid increase in water table levels. A second ADEC permit stipulated that the dewatering discharge be regularly monitored for contamination levels. The paper describes the quality control plan developed for this purpose. It includes hourly effluent sampling, GC testing and water table depth measurements. By the time the contractor excavated and installed a new sewer line, the effluent contamination level rose above acceptable limits and dewatering was terminated. The rest of the project was completed during winter.

The University of Alaska Anchorage (UAA), School of Engineering began web-enhanced graduate instruction of arctic engineering and related topics in 1998 and plans to provide a series of Arctic Engineering graduate courses completely online by 2004. The program begins with the popular keystone course CE A603 "Arctic Engineering," which is associated with engineering registration with the State of Alaska. Many of the evolving principles of online education are taken to their limits in the preparation and delivery of such specialized computation-oriented topics. Engineering graduate students are typically motivated learners with a practiced toolkit of study skills that lends itself to asynchronous online learning. The UAA experience has revealed important lessons regarding web delivery of graduate-level technical education that have led to continuing improvements in modular learning materials and interactions between instructors and students.

Successful rural Alaska projects are dependent upon the relationship developed during project development between the government funding agency and the rural community. Most rural Alaska communities are Alaska Native villages. This paper identifies the challenges to effective community involvement during project development. These challenges are reviewed from three viewpoints, "The 3 C's": 1) Complexity of the issues that are being dealt with; 2) Cultural factors impacting the relationships; and 3) Communication challenges the relationship must work through.