Greencore Pipeline Project
Denbury has completed the construction phase and placed into service the 325-mile, 24” Green Pipeline. The pipeline begins in Donaldsonville, Louisiana with a terminus point at the Hastings Field, south of Houston, Texas. The pipeline was designed to transport both natural and anthropogenic CO2. During construction in 2010, the pipeline was constructed across Galveston Bay which allowed for opportunities to steward good environmental, ecological, and safety practices.
Video of Green Pipeline Construction
The Green Pipeline route across Galveston Bay was designed to avoid impacts to the fragile shoreline, adjacent wetlands, and an existing U.S. Fish and Wildlife Service restoration site. As the pipeline intersected the important Houston Navigational Channel, horizontal directional drilling (“HDD”) technology was used as a safe alternative to working within the active channel in order to not impede vessel traffic. HDD’s were utilized for both shore crossings to avoid cutting the shorelines and to minimize ecological impact. The HDD at the Smith Point shore was also extended to the maximum extent to encompass pipeline crossings, as they typically increase water bottom disturbances.
As the project developed and benthic surveys identified both ecologically and economically important oyster resources, the pipeline was adjusted to avoid or minimize impacts to ecologically significant reefs. The design to surgically trench through the Dickinson Reef Complex and separate the material and restore the site with native material was approved by regulatory agencies. To offset the temporary impacts, Denbury, with the assistance of the Texas Parks and Wildlife Department, designed a series of seven small reefs south of the project site. As opposed to installing a single elongated reef, the seven small reefs had an increased edge effect, which is ecologically desirable. The individual reefs provided an interface with the nutrient rich current meandering between and amongst the smaller reefs, enhancing the fish habitat value.
As the pipeline advanced from the western shoreline of Galveston Bay, the project encountered the Nature Conservancy’s Attwater’s Prairie Chicken Preserve. The preserve is home to the endangered Attwater’s Prairie Chicken and is the site of the last naturally breeding population. Through close coordination with the preserve management group, the project team managed the construction window to avoid the critically sensitive breeding and nesting periods. The route was also adjusted to position the pipeline north of the existing east/west protection levee, avoiding the disturbance of flood protection levees.