Evaluation of a vertical frozen soil barrier at oak ridge national laboratory

Arctic Foundations, Inc. (AFI), of Anchorage, Alaska, has developed a freeze barrier system designed to hydraulically isolate a contaminant source area. The system can be used for long‐term or temporary containment of groundwater until appropriate remediation techniques can be applied. The technology was evaluated under the United States Environmental Protection Agency's (EPA's) Superfund Innovative Technology Evaluation (SITE) program at the United States Department of Energy's (DOE's) Oak Ridge National Laboratory (ORNL) facility in Oak Ridge, Tennessee. For the demonstration, an array of freeze pipes called “thermoprobes” was installed to a depth of 30 feet below ground surface around a former waste collection pond and keyed into bedrock. The system was used to establish an impermeable frozen soil barrier to hydraulically isolate the pond. Demonstration personnel collected independent data to evaluate the technology's performance. A variety of evaluation tools were used—including a groundwater dye tracing investigation, groundwater elevation measurements, and subsurface soil temperature data—to determine the effectiveness of the freeze barrier system in preventing horizontal groundwater flow beyond the limits of the frozen soil barrier. Data collected during the demonstration provided evidence that the frozen soil barrier was effective in hydraulically isolating the pond.     

SEDIMENTATION IN LAKE ONALASKA,NAVIGATION POOL 7, UPPER MISSISSIPPI RIVER,SINCE IMPOUNDMENT1

ABSTRACT: Sediment accumulation was evaluated in Lake Onalaska, a 2800-ha backwater impoundment on the Upper Mississippi River. Computer programs were used to process fathometric charts and generate an extensive data set on water depth for the lake. Comparison of 1983 survey data with pre-impoundment (before 1937) data showed that Lake Onalaska had lost less than 10 percent of its original mean depth in the 46 years since impoundment. Previous estimates of sedimentation rates based on Cesium-137 sediment core analysis appear to have been too high.     

BENTHIC MACROINVERTEBRATE COMMUNITY STRUCTURE IN A GREAT PLAINS STREAM RECEIVING FEEDLOT RUNOFF1

ABSTRACT The effect of feedlot runoff on the environmental quality of the Cottonwood River in east central Kansas was evaluated by analysis of community structure of benthic macroinvertebrates using the species diversity index, (d). The benthic fauna along the study reach was dominated by mayflies, caddisflies, midges, riffle beetles, and the pelecypod, Sphaerium. Sixty-five taxa were identified during the study; the benthic fauna was most abundant during the 1968–69 segment of the study. However, the mean 3 per station indicated the river was subject to moderate environmental stress, and 3's of those stations immediately downstream from feedlots were significantly lower than the 3 at the control station. There was a significant increase in d's during the 1970–71 segment of the study, following the closing of two feedlots. The results indicate periodic feedlot runoff had a continuing adverse affect on the environmental quality of the river, but recovery was rapid as the organic load on the river was reduced.     

FOREST HYDROLOGY AND EXTREME RAINFALL FREQUENCY1

Extreme rainfall frequency analysis provides one means to predict, within certain limits of probability, the average time interval between the recurrences of storms of a specified duration and magnitude. This in turn furnishes the forest hydrologist a valuable tool for engineering design and runoff and erosion forecast. A modification in the application of the annual maximum and annual exceedance series analysis described by V. T. Chow can, for special purposes, lead to an even more useful estimate of extreme events on a seasonal basis. This can be particularly important on small forested headwater watersheds where the runoff response to extreme rainfall may vary considerably with seasonal changes in canopy cover and soil moisture characteristics. Although the application of data covering a relatively short period of record has produced some inconsistencies among the frequency diagrams, under certain circumstances for short-term recurrence interval forecast and for non-critical application the analysis of extreme rainfall frequency from less than 20 years data seems justified.     

Natural vs. plantation forests: A case study of land reclamation strategies for the humid tropics

Biomass and productivity were compared in two plantations and in one stand of natural regeneration on similar sites in a premontane moist forest region of Puerto Rico. While initial growth rates of plantation species were higher, after four decades productivity of the natural regeneration plots was equal to or greater than productivity of the plantations. For the first 44 years, aboveground biomass of natural regeneration increased at an average annual rate of 3.8t·ha^–1·yr^–1, but the last year of the study it was 14.7t·ha^–1. Biomass increment of a pine plantation averaged between 8 and 10.5t·ha^–1·yr^–1 except for one year when the rate was much lower, possibly because of hurricane damage. A tropical hardwood plantation averaged close to 4t·ha^–1·yr^–1 for 41 years. It is suggested that in countries where funds for land reclamation are limited, intensive plantations may not always be the best strategy. Natural regeneration or shelterbelt plantations may be suitable alternatives.