Deep Compaction Resulting from Pipeline Construction - Potential Causes and Solutions

摘要

Alliance Pipeline L.P. (Alliance) constructed its pipeline facilities in 1999 and 2000 through highlyproductive agricultural regions in the Midwest. Although Alliance's right-of-way reclamationwas largely successful, selected land tracts on the construction right-of-way were observed tohave reclamation problems that reduced crop yields as compared to cropland adjacent to theconstruction right-of-way, as well as compared to the construction right-of-way on other landtracts. Common problems observed on the right-of-way included ponded water, soil saturation,and stunted crops. As a result of reclamation research review and consultation with reclama-tion experts, Alliance identified soil compaction as a potential primary cause of reduced cropproductivity in certain geographic areas. An applied field study was conducted to evaluate soilstrength (a measure of compaction) in areas exhibiting symptoms of compaction. Most evaluatedtracts had deep soil compaction (>10 inches deep) on the construction right-of-way as comparedto measurements off right-of-way. Ripping was conducted to a minimum depth of 20 inches ontracts with deep compaction in an attempt to alleviate soil compaction and to improve crop yields.Results of the study indicate that ripping largely reduced soil compaction. However, crop yieldresponses to ripping varied by crop species. Soybeans did not show a consistent yield response,while corn yields consistently increased after ripping. This difference in crop response is likely aresult of differences between the species in root structure and rooting depth. Potential causes ofdeep compaction were also evaluated as part of this study. Axle loads of construction equipmentwere found to be a potential cause of deep soil compaction. Soil moisture was also evaluated as apotential cause of deep soil compaction. High soil moisture content would have made soils moresusceptible to deep compaction from construction traffic (Soehne, 1958). Above normal rainfalloccurred in most of the study areas during construction, which contributed to the soil profile'ssusceptibility to deep compaction.