The purpose of this project aims to reinforce main branch and roadside gutters of Kaohsiung City cleaning and maintenance. For facilitate proper drainage, cleaning work is supposed to be finished before tide season in order to avoid overfilling around city center during rainy season. The main schemes of this project are divided into 5 programs, preliminary, inspecting gutters, ditch cleaning, ditch dredging, checking the quality of operation and efficiency assessment. 1. Personnel and equipment configuration In this project, the main work is based on manpower and the auxiliary are equipments. For one team, 10 people with an engine pressure washer and sludge removal vehicles are required. The other one is 5 people with a sewer cleaner (vacuum/jetting tanker), excavator and sludge removal vehicles. All equipments meet regulatory requirements of this project. Moreover, an additional excavator is using for a specific working area in order to meet demand of cleaning side sewer of mountain. 2. Cleaning up gutters The Contract of this project was started from 19 Sep 2012 to 18 Sep 2013. Besides gutters cleaning program had not been accomplished in September 2013. By 15 Aug 2013, all the work has met contract requirement. The total length of cleaned gutters is 150,114 m, which took 100.08% of the achievement rate. Mud cleaned out from roadside gutters is transported by sludge removal vehicles (612-BU、 Z6-226) , belongs to a legal cleaning and removal industry, to landfill ( Gangshan, Qishan and Daliao) for disposing. Total amount of cleaned volume is 1031.49 tons which is carried by146 cars. 3. Checking the quality of operation From September 2012 to August 2013, 147 abnormal side gutters was found, including 45 serious clog caused by covering flowerpot and malignantly blocked up, and 29 illegal pipelines hanged inside side gutters. Overall, poor construction and drain cover take 37.4% and 36.7% of influences during cleaning side gutters, therefore quality of construction and gutters maintenance should meet higher requirement. In total, 130 in site checked by inspection team, including 119 are qualified and 11 with defect, and the most of common defects could have immediate improvement, for example: workers did not wear safety vest, lacking of traffic safety cones, no traffic directors, roadside stacked with ditch mud without sweeping and labors worked slothfully. However, these defects had been reformed after inspecting intensively. During the working period, occupational injuries and accidents had never been caused. 4. Efficiency assessment (1) Factors affecting ditch cleaning In order to investigate factors related to design of drawdown slope, defected construction, section and depth of gutter, intake design and construction, and pollution from surrounding. According to inspection, 147 defective gutters could be refereed to several reasons shown as the following, 15 defected designs, 55 defected construction, 54 defected drain cover and 23 tainted by environment. To conclude, drain construction and covers have significant influence on ditch dredging and maintaining, which take 37.4% and 36.7 of influences during cleaning side gutters. (2) Gutter cleaning efficiency analysis Regarding to result of inspection, the most relevant program of gutters cleaning is highly recommended as the following: 15 people are arranged into a team to carry out gutters cleaning and it also requires 1 sewer cleaner (vacuum/jetting tanker), 1 mud sweeper and equipment. Moreover, staff arrangement is listed as the following, 1 site supervisor is in charge, 1 traffic director, 1 gutter cleaning trunk driver, 1 sewer cleaner (vacuum) operator, 1 sewer cleaner (jetting) operator. On the other hand, 10 people are assigned to work by manpower. (3) Frequency of gutters cleaning The target of this project aimed at major and minor flood-prone area in Kaohsiung County. Based on different gutter width and surrounding, 10 roadside gutters were selected from each area for investigating their sewer sediment. The investigative data was applied to estimate for 12 months by logarithmic regression analysis of Microsoft Office Excel. Thus, the recommended frequency of gutters cleaning and control objectives are referring to the following conditions: A. If the depth of gutter sewer = 0.15m, (A) When gutters locate at urban residences or countryside, and the width of roadside gutters is 4m, the control objectives should be qualified after carrying out 16 months cleaning program. Furthermore, cleaning frequency depends on sewer sediment after 12 months cleaning program, therefore, cleaning squad can make the most appropriate scheme for excusing gutters cleaning program. (B) When gutters locate at city center and around traditional market, nearly 6 months cleaning program, the control objectives should be qualified. However, 16 months later, it will become a potential flood-prone area. Regarding to the consequence, 6 months cleaning scheme is the most relevant frequency for this program. But, if there is any particular pollution caused by emissions from factories and agriculture, frequency of cleaning can change to 4 and 9 months. Despite the relevant frequency, the authorities have to make more effort on inspection in order to prevent factories discharging sludge and wastewater or agriculture and livestock discharging pollution. B. If seawater intrusion causes to roadside gutters clogged by sand around low-lying coastal areas such as Ziguan, Mituo, Yong'an, Jiading, Gushan and Yancheng Dis., the control objectives will be qualified by carrying 1 month gutters cleaning program. 2 months later, these will become potential flood-prone areas, so carrying on gutters cleaning program per month is necessary.

the road side ditch;dredging jobs;efficiency assessment