A nine-year, $600-million riverbed remediation in northeastern Wisconsin—the world’s largest river cleanup of its kind—is proving that dredging doesn’t have to be drudgery. Operating in a mode more akin to just-in-time manufacturing and with laser-like precision, contractors there are using a very efficient system of mapping, dredging and filtering river sediment as they clean up 13.3 miles of the lower Fox River near Green Bay, home to the largest concentration of pulp and paper mills in the world. Slide Show Photo: Mike Larson/ENR Photo: Mike Larson/ENR Tetra Tech’s Ray Mangrum, left, and Steve McGee, right. Over the course of the
The U.S. Army Corps of Engineers is banking on a fabric coating, better fill and changes in scour aprons and anchor tubes to make a 5.7-mile-long installation of berm with a sand-filled, geotextile-tube core the most resilient and long-lived geotube beach-hardening project it has built to date. + Image Image: US Army Corps of Engineers Hardcore sand dune Photo: Angelle Bergeron/ENR Gulf-side anchor tube and apron will drop like a protective curtain if land is cut away. Related Links: Tubin' on the Isle Weeks Marine Inc., Cranford, N.J., is 20% complete on a $25.7-million contract to restore the beach of
The likely cause of the Dec. 22, 2008, collapse of a coal-ash pond at a Knoxville, Tenn., powerplant that contaminated a stretch of river differs from what the plant’s owner and hired engineer disclosed last month, according to independent engineering analyses and reviews. The new studies point to other factors, including mismanagement and water pressure, as more likely catalysts than the reason cited by the Tennessee Valley Authority. Photo: TVA Failure of Tennesee coal-ash impoundment may cost $1 billion to clean up. In a July 28 report, Marshall Miller & Associates, a Raleigh, N.C. engineering firm, says the “root-cause” analysis
The American Society of Heating, Refrigerating and Air-Conditioning Engineers has released for comment 18 proposed air-side control changes to its energy-use standard, ASHRAE/IESNA Standard 90.1. The proposals are intended to move toward 30% energy-cost savings in buildings. Specific comments can be filed by either July 19 or Aug. 3. Details are available at www.ashrae.org.
A construction team led by Spanish contractor Sacyr Vallehermoso SA has won the Panama Canal expansion’s largest contract to date, the design-build job to build a third set of locks on both the waterway’s Atlantic and Pacific openings. Photo: ACP Current Panama Canal facilities are a tight fit for ships. Related Links: Panama Widens Horizons Ten Minutes with CH2M Hill’s Mike Kennedy The team, which includes two U.S. engineers, proposes to construct the locks, a job estimated by owner Panama Canal Authority (ACP) to cost $3.48 billion, for $3.12 billion, ACP said on July 8. � ACP says that the
A recent study from the National Academy of Sciences predicts so-called “green” refrigerants that replace ozone-depleting ones will contribute to global warming if left unchecked. Published last month in the Proceedings of the National Academy of Sciences, the study presents new data about modern hydrofluorocarbons (HFCs), which are considered greenhouse gases. The study claims HFCs could contribute the equivalent of up to 45% of carbon-dioxide emissions by 2050. Under that worst-case scenario, even if countries adopt a 450-ppm cap on CO2, “You still would have overshot it by about 50%,” says Mack McFarland, a scientist at refrigerant maker DuPont and
To safeguard downstream residents, work now is under way in California to seismically upgrade the San Pablo Dam. The $54-million project involves removing an existing buttress, strengthening the downstream foundation using cement deep-soil mixing and constructing a new 85-ft-high by 950-ft-long buttress. The San Pablo Dam, located near El Sobrante, is an 89-year-old, 38,600 acre-ft drinking-water impoundment. It is managed by the East Bay Municipal Utility District (EBMUD), which serves 1.3 million people in parts of Alameda and Contra Costa counties. Photo: EBMUD Trestles carry flumes (above) for building the original dam, while soil-mixing augers now work to strengthen the
The U.S. Army Corps of Engineers and contractors building a $695-million storm surge barrier in New Orleans are wrangling with the U.S. Coast Guard over an evacuation plan for heavy equipment that neither stymies construction nor risks damage to levees and floodwalls from storm-tossed vessels if a hurricane comes in. The Coast Guard is demanding the armada of floating equipment now at work on the Inner Harbor Navigation Canal Lake Borgne Storm Surge Barrier clear the area if a storm threatens. Typically, many tropical storms pass within a five-day run of the city during a hurricane season. This year, that
An unstable and weak slime-like foundation was the primary factor behind the Dec. 22, 2008, catastrophic failure of a coal-ash pond at Tennessee Valley Authority’s Kingston plant near Knoxville, Tenn., says a root-cause analysis released last week by AECOM Technology Corp. TVA hired the firm after the accident to determine why dikes holding coal-waste slurry failed, flooding 300 acres around the plant and the Emory River with 5.4 million cu yd of coal ash. Photo: TVA Spill cleanup could cost $1 billion. Los Angeles-based AECOM’s analysis determined the dikes’ angle and setbacks, increased loads because of recent high fill and
Despite sagging revenue at state and local levels, numerous environmental projects in the U.S. are moving ahead, driven by continued regulatory demands and a growing interest in sustainability. In the water and wastewater market, funding sources began to stabilize this spring as money from the American Recovery and Reinvestment Act helped prop up some plans and financing started to flow through the bond market again. Photo: CH2M Hill CH2M Hill has a $110-million contract for Superfund work in the western U.S., which includes the Iron Mountain site in Redding, Calif. Related Links: The Top 500 Design Firms: How Long Will
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