The Tennessee Valley Authority has had a second leak at an impoundment at a coal-fired powerplant, this time from a gypsum pond at its Widows Creek Fossil Plant in northeast Alabama. The incident prompted Sen. Barbara Boxer (D-Calif.) to announce on Jan. 13 that she plans to seek federal regulation of coal-ash ponds across the U.S. Shifting gypsum dislodged the cap covering a 30-in. pipe once used to drain water from the gypsum pond into an adjacent settling pond, says John Moulton, a TVA spokesman. Once the cap came off, water in the gypsum pond flowed into the settling pond,

Every fall, during low-water time on the Mississippi River, a crew of about 300 men and women turns out to resume one of the longest-running and most important construction projects of the U.S. Army Corps of Engineers—the placement of articulated concrete mattresses along the levees to prevent scour and protect communities. Slide Show Photo: Angelle Bergeron / ENR The operation requires a river of cable, fed up from below decks. Related Links: Mat Sinking on the Mississippi Photo: Angelle Bergeron / ENR With most new placement done, the casting yards have dwindled from five to three and the specialized units

The normal clutter of braced shoring is absent on a U.K. job to replace viaduct bearings near London because the shoring firm has created a cheaper and simpler megaprop system by bolting together standard stock. “We’ve never made these composite props before,” says Ian Fryer, engineering director for supplier RMD Kwikform Ltd., Walsall. “We hadn’t thought of it.” Photo: RMD Kwikform Ltd. A propping system to support a bridge under reconstruction can handle varying heights and pier configurations. Related Links: Agile Robots Can Climb High Places Replacing the 108 bearings is part of a $9.2-million project to refurbish Country Way

Sustainable features of the Vancouver convention center expansion go beyond daylighting controls, some natural ventilation, the 2.4-hectare green roof with 400,000 plants and grasses and restoration of 200 ft of shoreline and 1,500 ft of marine habitat. There also is a “blackwater” wastewater treatment and reuse system, for plant irrigation and toilets, connected to a roof-top stormwater management and reuse system. Slide Show Photo: LMN Architects Green roof can be irrigated using building’s treated water. Related Links: Stupendous Setting Is Crummy Site Habitat Apron Cooked Up To Mitigate Impact on Marine Life The building, going for a LEED Gold rating,

The foundation engineer calls the $8.2-million artificial reef—the marine habitat apron—the most unusual element of the Vancouver convention center expansion project. “I know of nothing else like it, anywhere,” says Ryan MacPherson, project engineer for WorleyParsons Westmar Consulting Engineers, North Vancouver. “It’s very successful.” Marine life is already growing. Slide Show Photo: LMN Architects Marine habitat apron, an artificial reef, is attached to the marine platform. Precast was placed by barge-mounted cranes. Related Links: Stupendous Setting Is Crummy Site Water Treatment and Reuse Reduces Use of Potable Water The 400-meter-long apron resembles long stadium bleachers, consisting of 86 bays of

Canada’s $730-million Vancouver convention center expansion on the city’s waterfront sits on the best of sites. To the north are breathtaking views of Coal Harbor, Burrard Inlet and the North Shore Mountains. Across the street to the south is the city center. Directly to the west is the landmark Stanley Park. Slide Show Photo: VCCEP Team Related Links: Habitat Apron Cooked Up To Mitigate Impact on Marine Life Water Treatment and Reuse Reduces Use of Potable Water Photo: LMN Architects Building could not block street and park view corridors. But the 106,000-sq-meter project in seismic British Columbia also sits on

It is not surprising that architects in the earthquake-prone San Francisco Bay Area incorporate robust and sophisticated seismic technologies into their buildings. Some of the earthquake-resisting strategies in the region’s high-profile new-construction projects, such as the coupled shear-wall system inside the twisting and turning tower at the de Young Museum or the base isolators below the just-completed Oakland Cathedral, naturally attract attention because of their unusual design. But older, more conventional structures are continuously being subjected to seismic retrofit and they require at least just as much engineering finesse. Slide Show A seismic retrofit is part of plans to transform

A planned rail transit spur in northern Virginia has moved another step forward, with U.S. Transportation Secretary Mary E. Peters' approval of a $900-million, multi-year federal funding commitment towards the project's $2.6-billion first phase. With Peters' Jan. 7 action, the proposed "full funding grant agreement" goes to Congress for a 60-day review. Slide Show Photo: Metropolitan Washington Airports Authority First phase would carry line part way to Dulles airport. Related Links: FTA Approves First-Phase Funds for Virginia Rail Project The $900 million would help finance an 11.6-mile first stage of a planned 23-mile extension of of the Washington Metropolitan Area

Ten-mile hikes, wasp nests and forest fires marked an almost unfeasible feasibility study for a potential world-record road tunnel. Engineering geologists with Kleinfelder Inc., San Diego, are now working on a report, due by fall, for the Orange County Transportation Authority and Riverside County Transportation Commission. It will assess the possibility of building a pair of 50-ft-dia tunnels almost 12 miles long under the Cleveland National Forest in Southern California. Photo: Klienfelder Rugged test sites required a full-time helicopter. Engineers say tunnel-boring technology is not quite there yet, but might be by the time the agencies find funding and complete

The Texas Dept. of Transportation announced on Jan. 6 that it pulled the plug on the estimated $200-billion Trans-Texas Corridor, a vision introduced by TxDOT and Texas Gov. Rick Perry (R) in 2002. TxDOT Executive Director Amadeo Saenz Jr. made the announcement during the fourth annual Texas Transportation Forum in Austin. Projects already started under the heading of the Trans-Texas-Corridor will continue as a series of individual projects. Portions of two TTC projects are under development: Interstate 69 from Texarkana/Shreveport to the Mexico border and the I-35 corridor from north of Dallas/Fort Worth to Mexico. Perry cited financing as a