The Current Situation and Circumstances Regarding the Great Earthquake Damage Ishinomaki District Water Supply Authority Junichi Takaki, Deputy Technology Director 116 Shinkaminuma Hebita Ishinomaki-city Miyagi 986-0861 Japan E-mail: [email protected] Abstract The cities of Ishinomaki and Higashi Matsushima in Miyagi Prefecture, which our corporation's supplies water, are located on the Sanriku Coast in the Tohoku region, so they sustained massive damage from the earthquake, moreover from the unprecedented gigantic tsunami caused by seismic activity. About one and a half years have passed since the disaster and emergency restoration has been completed. Our corporation has situated this fiscal year as the first year of reconstruction, and is systematically driving business operations forward. The biggest job is the relocation of the water treatment plant. The Hebita water treatment plant, which has the capacity to process 55,000m3 of water per day, was shaken by the seismic activity, and the area surrounding the structure along with its support base was liquefied, which created cracks and leakage in the settling basin and caused massive damage to the pipes in the plant. In the case that an earthquake of such magnitude occurs again, it is feared that water processing will stop functioning, and that there will be a water outage for a long period of time. Restoring at the current location will require time and money because of operating the existing facilities at the same time. So we have a plan to transfer all functions of the Hebita water treatment plant to the Sueyama water treatment plant, which has a solid foundation and wasn’t affected by the tsunami, until FY2014. In addition, the decrease of the population supplied with water and the suspension of operations at the plant that many people use have caused an extreme decrease in income from water utilities charges. On the one hand, it is expected that restoration work will cost a lot of money. So in order to continue the stable administration of water supply operations from here forward, it is important for us to secure the source of the strong financial support, for example the support we have received from the country, along with reducing the cost of providing water. The areas which received massive damage from the tsunami have carried out restoration in the reconstruction plans of Ishinomaki and Higashi Matsushima, and it is requested for us that the improvement of water supply facilities has to be flexible in response to a variety of reconstruction measures such as the relocation of disaster prevention groups and the construction of roads with high embankments. Keywords Ishinomaki Higashimatusima The Great Tohoku Earthquake Introduction A little more than a year has passed since the Great Tohoku Earthquake. I would like to take this opportunity to once again express our deepest thanks for the unsparing support and continued cooperation we are receiving from the whole country's water supply corporations and everyone who is related to water services in each area, beginning with the Japan Water Works Association along with the Japan Water Supply Technology Research Center, in response to the earthquake and tsunami damage. Today, since our corporation has taken this opportunity to report, I would like to present on ''The Current Situation and Circumstances Regarding the Great Earthquake's Damage.'' The Current Situation and Circumstances of the Great Earthquake's Damage The coast of Tohoku area received catastrophic damage from the tremors and the unprecedented giant tsunami caused by the Great Tohoku Earthquake. Within our corporation's water supply district, the maximum seismic intensity was recorded at the 6th highest level, and it was confirmed that the land sank as much as 1.2m depending on the area. In addition, the giant tsunami, centering on the coastal areas, was observed at a height of 8.6m in the city of Ishinomaki. 110k ㎡, that is 16.7% of the combined area of Ishinomaki and Higashi Matsushima, were flooded by the tsunami. In these two cities 4,882 people are dead or missing and 25,187 houses were completely destroyed; that number comes to 60,685 houses including largely destroyed, half destroyed, and partly destroyed houses. Current Business Volume The damage caused by the tsunami has greatly affected our business volume. At the end of 2011, we supplied water to 192,304 people and 72,506 houses, 11,537 people and 2,780 houses less than 2010, before the disaster. Restoration Progress Our water treatment plants stopped functioning due the power outage which continued after the outbreak of the disaster, and all of the 75,673 houses lost their water supply. Beginning with water supplies from emergency medical institutions such as the Ishinomaki Red Cross Hospital five days after the disaster, on the 16th of March, we steadily continued to restore our operations in conjunction with emergency water supplies, but all of the houses lost their water supply again due to the aftershock on the 7th of April, and the many pipes were damaged again. The areas which suffered from the tsunami had to continue emergency restoration while disposing of the scattered rubble and the accumulated toxic sludge; furthermore, there was flooding due to the sinking of the land along with the rise of the sea level and the underground water level; restoration work was extremely difficult. Currently, aside from the areas which received tremendous damage from the tsunami, restoration work is largely completed. The Situation of the Damaged Water Supply Facilities There were 187 cases of damage to water supply facilities such as water treatment plants as of October, 2011. Among those, our organization's main water treatment plant in Hebita, which had the ability to process 55,000 cubic meters of water, was flooded 50cm by the tsunami, and in addition the structure along with the pipes inside received a tremendous amount of damage from the shaking and the liquefaction caused by the earthquake. The section which connects the mixing basin to the water conduit and the first and second settling basins were cracked all the way down to their bases, and damage to the expansion joint caused leakage. The main parts of the pumping structure, such as the pillars and beams, were damaged, and there were many incidents of leakage from the pipes inside; the damage was tremendous. 68 cases of damage inside the Hebita water treatment plant were confirmed, and the functioning of one of the three water treatment systems, which processed 15,000m³ of water, stopped for four months. Currently, we have finished emergency restoration to the extent that there are no obstacles to our water processing, but due to the sinking of the land's foundation caused by the phenomenon of liquefaction, the stakes directly below the frame's base are protruding and a gap has formed, so restoration is under difficult circumstances. In the case that we are once again struck by a big earthquake like this one, it is feared that water treatment will stop functioning and that about 50% of our district will lose its water supply for an extended period of time. As a result, we will transfer all of the functions of the Hebita water treatment plant to the Sueyama water treatment plant, which is situated on high ground and has a strong foundation, until 2014 because we need time and money for restoration at the current location. The water treatment capacity of the Sueyama plant, which was 25,000m³ of water per day, has become 80,000m³ since all of the functions of the Hebita water treatment plant were transferred, and it has become a rapid filtration-style water treatment plant. Next, concerning the coastal areas, Ogatsu district's Ohhama water treatment plant, almost no time after being outfitted, along with Kitakami district's Aikawa water treatment plant received catastrophic damage from the tsunami as their membrane filtration-style equipment was destroyed. Currently, temporary portable membrane filtration-style equipment is installed and water supply has commenced. Concerning the drawing of water at the Aikawa and Ohhama water treatment plants, from now on it is necessary to make sure of the water quality in these districts in such ways as measuring the density of chloride ions in the water and continually inspecting the electrical conductivity of the water and so on using water quality gauges because the water quality at the source is unstable due to the increase of chloride ions. And the introduction of maintenance and renewal programs based on asset management is also under consideration for the restoration of water supply facilities. The Circumstances of Damage to Pipes 2,356 incidents of pipe damage occurred including all of the water conveyance, water transmission, water distribution, and water supply pipes. Among those, there were 1,396 incidents involving water supply pipes, the most numerous, comprising about 60% of the whole. There were 623 incidents of damage to the actual pipes and 62 incidents of damage to attached facilities, 0.37 incidents per kilometer. The details are as follows: ① 69 incidents of damage to cast-iron pipes, mostly leakage from the joints. ②221 incidents of damage to ductile cast-iron pipes. Among those, 0 incidents of damage occurred in the 172.2km of earthquake-resistant joints. ③32 incidents of damage to steel pipes. ④256 incidents of damage to PVC pipes, the most numerous, in the form of damage to joints. ⑤32 incidents of damage to asbestos cement pipes. ⑥13 incidents of damage to polyethylene pipes. The damage of the coastal areas was massive; roads and piers are crumbling and water distribution pipes are exposed due to the tsunami, and there was damage to the bridge-attached pipes due to ruptures and contact with flotsam.