The Environmental Protection Agency on Nov. 9 issued a subpoena to oil-field services contractor Halliburton for failing to provide information the agency needs to complete its congressionally mandated study on hydraulic fracturing, or “hydrofracking.” Eight other hydrofracking firms that received voluntary information requests in September agreed to submit “timely and complete information” to EPA, the agency said. But Houston-based Halliburton took another tack, refusing to give EPA full data on the company’s hydraulic fracturing operations over the past five years. “Because the agency’s request was so broad, potentially requiring the company to prepare approximately 50,000 spreadsheets, we have met with
Arch dams, classically curved monoliths situated in narrow valleys, are not as common as other types of dams, such as embankment dams and gravity dams. ENR takes a look at some of the biggest arch dams in the world, both completed and under construction.