Wednesday, July 03, 2013
Tom Aley, senior hydrogeologist and president of Ozark Underground Laboratory, said in expert witness testimony filed Friday before the Arkansas Public Service Commission (APSC) that an Environmental Impact Statement (EIS) prepared for the 48-mile-long proposed high voltage transmission line is inadequate and inaccurate.
Aley testified for Save the Ozarks, and focused on three general topics he noted as major flaws in the EIS:
- Karst conditions that require substantially expanded subsurface investigations beyond those identified and assessed in the EIS. Karst geology is an area where soluble rocks such as limestone can result in caves, springs and sinkholes.
- Identification and protection of threatened and endangered species’ habitats and karst features consistent with comments by the U.S. Fish and Wildlife Service.
- Incompatibility between the project schedule identified in the EIS and the need to adequately deal with foundation and environmental issues.
Aley said the EIS does not include any description of the geology of the corridor and does not identify or discuss the limitations this geologic setting creates for the construction of a safe and reliable transmission line.
“The EIS does not identify the nature of foundations proposed for use to support the tubular steel poles and does not identify subsurface investigations that would be made prior to constructing the foundations,” he said. “The EIS does not indicate that any foundation investigations will be conducted prior to, or in conjunction with, the construction phase.
“The abundance of bedrock cavities along the proposed SWEPCO transmission line can only be determined by foundation investigations, but... subsurface solutional cavities in karst landscapes can represent significant risks for structures.”
Aley said there are useful similarities between wind turbine structures and the proposed 345 kV poles proposed by SWEPCO. For example, both have widely spaced structures with small footprints. Few, if any, of the investigative approaches used by geologists and geological engineers evaluating wind power sites in karst landscapes have been considered, much less proposed, for use by the consultant to SWEPCO, he said.
“Transmission line structures that fail to give adequate consideration to karst features and conditions and do not include adequate subsurface investigations (including borings) pose an appreciable risk of failure that in some cases could be catastrophic,” Aley said. “If the SWEPCO transmission line is to be constructed with poles 150 feet tall and no guy cables then a substantially improved program of subsurface investigations will be required to ensure that the people of Arkansas receive a reasonably safe and reliable transmission line.”
Another flaw identified by Alley is that the EIS does not propose any meaningful actions to protect karst habitats and features including caves, sinkholes, springs and losing streams. He said correcting this omission would require the following:
- The 300 ft. natural area buffer around a karst feature or losing stream will require identification of all such features both within the 150 ft. wide corridor and 300 feet on either side of the corridor. As a result, the total width of the area to be searched for such features will be 750 feet.
- The protection of water quality in losing streams is critical both to native species and to private water supplies. It is critically important that all losing streams in the corridor area be protected with at least a 300-ft. wide natural area buffer on each side of the stream channel.
- Cutting or clearing of trees over three inches in diameter at breast height from the right-of-way for on-going construction of I-69 in south central Indiana has been limited by the USFWS to the period from November through March to protect Indiana bats using trees from “incidental take.” It seems both likely and appropriate that the Arkansas field office of the USFWS will make similar requirements for clearing associated with the SWEPCO transmission line.
Asked if he had formed an opinion regarding the extent to which SWEPCO’s project as proposed avoids environmental damage, Aley said construction and operation of the transmission line would result in significant erosion on steep slopes with resulting degradation of water quality. Much of the eroded sediment would enter the karst groundwater system through losing streams and other karst features. He said this would degrade groundwater quality in receiving springs, caves and private wells. In addition, aquatic cave and groundwater habitats would be degraded.
Aley said it is likely the transmission line will pass very close to caves that provide habitat for the gray bat and the Indiana bat, both listed on the federal endangered species. “The potential adverse impacts of the transmission line EIS and its maintenance on these species has not been professionally evaluated in the EIS and could be significant,” he said.
Comments:Be the first to comment!
Login to comment!