Salmon fed the bellies and the souls of the local tribe, the Lower Elwha Klallam, for millennia. A tribal elder recalled that as a little girl she once helped prepare a salmon so big it took her mother three steps to walk from the head to the tail. Then Thomas Aldwell erected his dams and brought the salmon, and the river, to ruin.
Cracks Painted On Dams
Once the Port Angeles citizens committee came aboard, Slade Gorton was left nearly alone in his opposition to dam removal. He held the Elwha dams hostage for a few more years before being swept out of office in 2000. Soon after $325 million in dam removal money came through.
American Rivers works to protect the legacy of healthy, wild rivers. We're proud to have them as an organizational partner with The Memory of Fish. Spend some time on their site and learn how to take action for rivers. American Rivers provides information on dams and dam removal here.This classic photo is by Mikal Jakubal, the activist who painted a crack and the words "ELWHA BE FREE" on the Elwha Dam in 1987.
Bernardo leads a team of engineers and hydrologists who plan water releases from Hoover Dam, as well as Davis and Parker dams downstream, sending flows that travel through pipelines and canals to Phoenix, Los Angeles and farmlands in the U.S. and Mexico that produce crops such as hay, cotton, grapes and lettuce.
There are millions of dams in rivers and streams across the United States, and many of them no longer serve their original purposes. In a new pair of reports, researchers at Resources for the Future examine the national extent of dam removal and how it may fit into the wider scope of dam regulation.
The first report, Dams and Dam Removal in the United States, uses nationwide data to paint a picture of the size, age, purpose and ownership type of dams across the United States. The second report, Aligning Dam Removal and Dam Safety: Comparing Policies and Institutions Across States, analyzes case studies of specific state-level dam safety programs and what could be done to improve the effectiveness of such programs.
Additionally, the sheer weight of the ice dam often causes gutters and downspouts to pull away from the house, sometimes bringing the fascia boards with them. Preventing ice dams helps avoid damage and costly repairs.
Ice dams are responsible for cracked plaster ceilings and walls, peeling paint, soaked carpets, and buckled wood floors. Less visible but no less destructive effects include drenched insulation, rotting joists, and the formation of mold. The most common form of ice dam damage is collapsed rain gutters, which can cost $100 to $300 per side to repair.
In order for ice dams to form, there needs to be roof snow buildup, home heat loss, and subfreezing temperatures. The more snow, the larger the heat loss, and the longer the subfreezing temperatures remain, the higher the likelihood that ice dams will materialize.
Delamination is the cracking and eventual peeling of paint from the surface of a plywood or composition wood substrate. Plywood cracks from its expansion and contraction with changes in moisture and temperature. Plywood is prone to cracking because of its original construction from thin sheets of wood.
If rust is present, use a wire brush and sandpaper to remove as much peeling paint and rust as possible. If the rusting is severe and cannot all be removed, apply a rust-converting coating, working it into the cracks, followed by a topcoat with a latex paint.
Ice dams should only be handled by a professional roofer or restoration company with the training and tools to fix an ice dam. Ice dams can cause things like water damage, mold damage or roof damage, and they all need to be handled by a professional.
The goal is to keep the entire roof the same temperature, whether by adding insulation, increasing ventilation or sealing off possible air leaks from the home to the attic space. Before winter arrives, Rhode Islanders should take the following three steps to protect their home or business from ice dams:
A cold attic and uniform roof temperatures might not be the perfect solution for all homes. Some roof types are difficult to insulate and vent. Particular sections may be impossible to keep cold. Meanwhile, angled ceilings, low-sloped roofs and buildings without attics pose their own unique challenges. Winters with heavy snowfall sometimes cause ice dams no matter the temperature of your roof.
If you see the signs of ice dam damage and require an immediate solution, you can use temporary ice dam fixes to cover the symptoms until professional help arrives to address the underlying problem. Quick solutions for existing ice dams may include:
When it comes to removing heavy walls of ice, many professionals rely on heated steam to safely melt the snow and allow the water to run entirely off the roof. While there are several temporary ice dam solutions, the best method of ice dam repair is to hire a professional restoration company. Rhode Island Restoration is a professional roofing solution to repair and restore your property, as well as prevent future ice dams from forming.
Insurance may help cover damage caused by ice dams in certain cases. When water builds up behind an ice dam, it may leak through the roof and cause water damage to the insulation, ceilings, walls and other areas. Personal property coverage may help pay to repair water damage and freezing. Depending on your policy terms and limits, this coverage could extend to mold damage repairs as well.
While information is still be gathered, early reports have stated that three environmental groups warned federal officials way back in 2005 that something like this could happen, and what's perhaps even more concerning is the fact that Oroville is just one of nearly 100,000 dams across the US that are in serious need of repairs.
"The last time the American Society of Civil Engineers issued its Infrastructure Report Card was in 2013, when it gave US dams a 'D' grade, and reported that more than 4,000 are deficient," Jacques Leslie reports for the Los Angeles Times.
Panicked messages from the Butte County Sheriff early on painted a vastly different picture to that of the California State Department of Water just hours later, and locals were left to wonder what was actually going on.
"We don't have details on the repairs, but they put cement into the cracks and troweled it over," Robert Bea, professor emeritus of civil and environmental engineering at the University of California at Berkeley, told the Associated Press.
The Oroville Dam is now almost 50 years old, and has never undergone the kinds of upkeep it clearly required, and as you can see in the graph below, it's just one of thousands of dams of a similar age:
"A 2016 survey by the Association of State Dam Safety Officials estimated the cost of repairing deficient dams that currently place downstream residents at risk at $22.91 billion," the Los Angeles Times reports.
Before the Second World War, the British Air Ministry had identified the industrialised Ruhr Valley, especially its dams, as important strategic targets.[3] The dams provided hydroelectric power and pure water for steel-making, drinking water and water for the canal transport system. Calculations indicated that attacks with large bombs could be effective but required a degree of accuracy which RAF Bomber Command had been unable to attain when attacking a well-defended target. A one-off surprise attack might succeed but the RAF lacked a weapon suitable for the task.[4]
The mission grew out of a concept for a bomb designed by Barnes Wallis, assistant chief designer at Vickers.[4] Wallis had worked on the Vickers Wellesley and Vickers Wellington bombers and while working on the Vickers Windsor, he had also begun work, with Admiralty support, on an anti-shipping bomb, although dam destruction was soon considered. At first, Wallis wanted to drop a 10 long tons (22,000 lb; 10,000 kg) bomb from an altitude of about 40,000 ft (12,000 m), part of the earthquake bomb concept. No bomber aircraft was capable of flying at such an altitude or of carrying such a heavy bomb and Wallis proposed the six-engined Victory Bomber for this purpose but this was rejected.[5] Wallis realized that a much smaller explosive charge would suffice if it exploded against the dam wall under the water but German reservoir dams were protected by heavy torpedo nets to prevent an explosive device from travelling through the water.[6]
In February 1943, Air Vice-Marshal Francis Linnell at the Ministry of Aircraft Production thought the work was diverting Wallis from the development of the Vickers Windsor bomber (which did not become operational). Pressure from Linnell via the chairman of Vickers, Sir Charles Worthington Craven, caused Wallis to offer to resign.[12] Sir Arthur Harris, head of Bomber Command, after a briefing by Linnell also opposed the allocation of his bombers. Wallis had written to an influential intelligence officer, Group Captain Frederick Winterbotham, who ensured that the Chief of the Air Staff, Air Chief Marshal Charles Portal, heard of the project. Portal saw the film of the Chesil Beach trials and was convinced.[13] On 26 February 1943, Portal over-ruled Harris and ordered that thirty Lancasters were to be allocated to the mission and the target date was set for May, when water levels would be at their highest and breaches in the dams would cause the most damage.[14] With eight weeks to go, the larger Upkeep mine that was needed for the mission and the modifications to the Lancasters had yet to be designed.
The operation was given to No. 5 Group RAF, which formed a new squadron to undertake the dams mission. It was initially called Squadron X, as the speed of its formation outstripped the RAF process for naming squadrons. Led by 24-year-old Wing Commander Guy Gibson, a veteran of more than 170 bombing and night-fighter missions, twenty-one bomber crews were selected from 5 Group squadrons. The crews included RAF personnel of several nationalities, members of the Royal Australian Air Force (RAAF), Royal Canadian Air Force (RCAF) and Royal New Zealand Air Force (RNZAF). The squadron was based at RAF Scampton, about 5 mi (8 km) north of Lincoln. 2ff7e9595c
コメント