LANDFILLS Essays - Waste Management, Landfill, Anaerobic Digestion

LANDFILLS Essays - Waste Management, Landfill, Anaerobic Digestion LANDFILLS Solid waste is the term that civil engineers use to refer to what most of us call garbage. Municipal solid waste is most familiar to us. It comes from households, institutions, and small businesess. These solid wastes enter the solid-waste stream, and the flow never ceases. While many normal activities are suspended during weekends and holidays, the flow of garbage is non-stop. Some holidays, such as Christmas, create an enormous wave of solid waste. There are essentially four ways to deal with garbage: 1) recycle it into something that can be used again, 2) dump it, 3) burn it, or 4) reduce the source of material products (such as packaging) in order to eliminate future garbage. Throughout history, dumping has been the preferred means of disposal. Today, landfills are America?s primary method for the disposal of garbage. Approximately 40 to 50 percent of everything we throw away is paper. Newspapers account for as much as 18 percent of the volume in a landfill. Grass clippings and raked-up leaves account for nearly 20 percent of our waste. Much of the notion that biodegradation takes place within a landfill is a myth. Some food and yard debris degrade at a very slow rate, but the remainder of the garbage in landfills seems to retain its original form, weight, and volume. Even after being buried in a landfill for several years, the print on newspapers remains legible. Landfills also contain a considerable amount of hazardous waste. Today, pesticides, cleansers, and motor oil are commonly found in most households. Many of these find their way to the trash. Therefore, landfills must be designed for the safe disposal of hazardous household waste. Currently, there is a critical shortage of landfills, expecially in the northeastern United States. It is estimated that 40 percent of the landfills now in use will close down within five years. The reason the percentage is so high is that most landfills are designed to be in use for only about ten years. Many landfills now closing are open dumps. Rain and groundwater trickle through the trash and dissolve metals and other chemicals. This toxic liquid, called leachate, can ooze into the ground and contaminate nearby wells and streams. In sanitary landfills, daily deposits of fresh garbage are covered with a layer of dirt or plastic or both. However, sanitary landfills can still exude leachate into the water table. In new sanitary landfills, the basin is often lined with clays and impermeable plastic sheets to keep the leachate in. While so many of the country?s landfills are closing down in the next several years, solid-waste engineers face tremendous challenges to properly seal, salvage, and monitor some of the nation?s most contaminated dumps. The use of sanitary landfills presents several additional challenges beyond safety and efficiency. One major problem is cost. It is often necessary to transport garbage several hundred miles to an available landfill. The cost for transporting garbage to a landfill can be excessive. An even bigger problem is location. Even if the landfill does not leak pollutants or foul the air, no one wants a landfill for a neighbor. Consequently, the old landfills are not being replaced. Due to the critical shortage of landfills and the concerns about their safety, environmental consciousness has been raised. There is a growing awareness of the need to improve the environment and become less dependent on landfills. We must finds ways to reduce waste, and we must find ways to convert waste into something that can be used again. Source reduction offers a real and lasting contribution toward solving our nation?s solid waste problem and conserving landfill space. Talk to your legislators, both federal and state, about this genuine method of reducing the volume of garbage.

Battle of Tarawa in World War II

Battle of Tarawa in World War II The Battle of Tarawa was fought November 20-23, 1943, during World War II (1939-1945) and saw American forces launch their first offensive into the central Pacific. Despite massing the largest invasion fleet to date, the Americans suffered heavy casualties during and after landing on November 20. Fighting with fanatic resistance, nearly the entire Japanese garrison was killed in the battle. Though Tarawa fell, the losses incurred led the Allied high command to reassess how it planned and conducted amphibious invasions. This led to significant changes that would be employed for the remainder of the conflict. Background Following the victory at Guadalcanal in early 1943, Allied forces in the Pacific began planning for new offensives. While General Douglas MacArthurs troops advanced across northern New Guinea, plans for an island hopping campaign across the central Pacific were developed by Admiral Chester Nimitz. This campaign intended to advance towards Japan by moving from island to island, using each as a base for capturing the next. Beginning in the Gilbert Islands, Nimitz sought to next move through the Marshalls to the Marianas. Once these were secure, the bombing of Japan could commence prior to a full-scale invasion (Map). Preparations for the Campaign The starting point for the campaign was the small island of Betio on the west side of Tarawa Atoll with a supporting operation against Makin Atoll. Located in the Gilbert Islands, Tarawa blocked the Allied approach to the Marshalls and would impede communications and supply with Hawaii if left to the Japanese. Aware of the islands importance, the Japanese garrison, commanded by Rear Admiral Keiji Shibasaki, went to great lengths to turn it into the fortress. Leading around 3,000 soldiers, his force included Commander Takeo Sugais elite 7th Sasebo Special Naval Landing Force. Working diligently, the Japanese built an extensive network of trenches and bunkers. When complete, their works included over 500 pillboxes and strong points. In addition, fourteen coastal defense guns, four of which had been purchased from the British during the Russo-Japanese War, were mounted around the island along with forty artillery pieces. Supporting the fixed defenses were 14 Type 95 light tanks. The American Plan To crack these defenses, Nimitz dispatched Admiral Raymond Spruance with the largest American fleet yet assembled. Consisting of 17 carriers of various types, 12 battleships, 8 heavy cruisers, 4 light cruisers, and 66 destroyers, Spruances force also carried the 2nd Marine Division and part of the US Armys 27th Infantry Division. Totaling around 35,000 men, the ground forces were led by Marine Major General Julian C. Smith. Shaped like a flattened triangle, Betio possessed an airfield running east to west and bordered Tarawa lagoon to the north. Though the lagoon water was shallower, it was felt the beaches on the north shore offered a better landing location than those on the south where the water was deeper. On the north shore, the island was bordered by a reef that extended around 1,200 yard offshore. Though there were some initial concerns as to whether landing craft could clear the reef, they were dismissed as planners believed the tide would be high enough to allow them to cross. Forces Commanders Allies Major General Julian C. SmithVice Admiral Raymond Spruanceapprox. 35,000 men Japanese Rear Admiral Keiji Shibasakiapprox. 3,000 soldiers, 1,000 Japanese laborers, 1,200 Korean laborers Going Ashore By dawn on November 20, Spruances force was in place off Tarawa. Opening fire, the Allied warships began pounding the islands defenses. This was followed at 6:00 AM by strikes from carrier aircraft. Due to delays with the landing craft, the Marines did not move forward until 9:00 AM. With the end of the bombardments, the Japanese emerged from their deep shelters and manned the defenses. Approaching the landing beaches, designated Red 1, 2, and 3, the first three waves crossed the reef in Amtrac amphibious tractors. These were followed by additional Marines in Higgins boats (LCVPs). As the landing craft approached, many grounded on the reef as the tide was not high enough to allow passage. Quickly coming under attack from Japanese artillery and mortars, the Marines aboard the landing craft were forced to enter the water and work their way towards shore while enduring heavy machine gun fire. As a result, only a small number from the first assault made it ashore where they were pinned down behind a log wall. Reinforced through the morning and aided by the arrival of a few tanks, the Marines were able to push forward and take the first line of Japanese defenses around noon. A Bloody Fight Through the afternoon little ground was gained despite heavy fighting all along the line. The arrival of additional tanks bolstered the Marine cause and by nightfall the line was approximately half-way across the island and nearing the airfield (Map). The next day, the Marines on Red 1 (the westernmost beach) were ordered to swing west to capture Green Beach on Betios west coast. This was accomplished with the aid of naval gunfire support. The Marines on Red 2 and 3 were tasked with pushing across the airfield. After heavy fighting, this was accomplished shortly after noon. About this time, sightings reported that Japanese troops were moving east across a sandbar to the islet of Bairiki. To block their escape, elements of the 6th Marine Regiment were landed in the area around 5:00 PM. By the end of the day, American forces had advanced and consolidated their positions. In the course of the fighting, Shibasaki was killed causing issues among the Japanese command. On the morning of November 22, reinforcements were landed and that afternoon the 1st Battalion/6th Marines began an offensive across the southern shore of the island. Final Resistance Driving the enemy before them, they succeeded in linking up with the forces from Red 3 and forming a continuous line along the eastern part of the airfield. Pinned into the eastern end of the island, the remaining Japanese forces attempted a counterattack around 7:30 PM but were turned back. At 4:00 AM on November 23, a force of 300 Japanese mounted a banzai charge against the Marine lines. This was defeated with the aid of artillery and naval gunfire. Three hours later, artillery and air strikes commenced against the remaining Japanese positions. Driving forward, the Marines succeeded in overrunning the Japanese and reached the eastern tip of the island by 1:00 PM. While isolated pockets of resistance remained, they were dealt with by American armor, engineers, and air strikes. Over the next five days, the Marines moved up the islets of Tarawa Atoll clearing the last bits of Japanese resistance. Aftermath In the fighting on Tarawa, only one Japanese officer, 16 enlisted men, and 129 Korean laborers survived out of the original force of 4,690. American losses were a costly 978 killed and 2,188 wounded. The high casualty count quickly caused outrage among Americans and the operation was extensively reviewed by Nimitz and his staff. As a result of these inquiries, efforts were made to improve communications systems, pre-invasion bombardments, and coordination with air support. Also, as a significant number of the casualties had been sustained due to the landing craft beaching, future assaults in the Pacific were made almost exclusively using Amtracs. Many of these lessons were quickly employed in the Battle of Kwajalein two months later.