Chapte Er 13 Ope Fac Eration a Cilities and Main Ntenance E of Wate Er
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Bengaluru Water Supply and Sewerage Project (Phase 3) Final Report Chapter 13 Operation and Maintenance of Water Supply and Sewerage Facilities 13.1 General Present arrangements for the operation and maintenance (O&M) of water supply aand sewerage facilities by BWSSB are as follows: (1) Water supply: Kavery Zone is responsiblle for the O&M of major facilities including intake, water treatment, transmission facilities and GLRs. The procurement of materials and equipment required is also undertaken by the zone. (2) Sewerage: Wastewater Management Zone is responsible for O&M of major sewerage facilities in- cluding larger size sewers with more than 400 mm dia., pumping stations annd STPs. Required pro- curement of materials and equipment is alsso under the responsibility of this zone. (3) Water distribution pipelines and smaller size sewers: Maintenance Zone is reesponsible for O&M of the facilities and Project Zone undertakes pprocurement of required materials and equipment. Required design of the facilities in the O&M work is undertaken by respective zones. While, for large size facilities such as WTP and STP, as being ppracticed in BWSSP Phase 2 Projectt, the private sector un- dertakes O&M of facilities for about seven (7) years after construction work, as a part of contract in ap- plication of design-buuild-operate for the construction of facilities. For the O&M of planned facilities, present practices by BWSSB shall basically employed considering expansion of water supply and sewer- age systems. O&M cost required for JICA Survey Project (Stage V project and major sewerage facilities for 110 vil- lages) is estimated baased on the power and chhemical requirements studied in thee preliminary design of facilities. Cost estimate presented in DPR for 110 Villages water supply and sewerage project is also ref- ereed to. 13.2 Water Supply 13.2.1 O&M of the Facilities to be Provided by Stage V Project Required O&M of the water supply facilities is discussed by major facility. (1) Intake facilities Water intake gates and screens sometimes occlude caused by the inflow of floating impurities and inorganic substances, resulted in malfunctioning of intake facilities and poor raw water quallity. Daily visual moni- toring of these structures and conduct of regulaar cleaning are important to maintain tthem in good condition. (2) Water treatment facilities 1) Flow Measurement The intake water amount shall be less than the water privilege. In this regard, accurate measurement of inflow volume is necessary. In addition, it is also important to control treatment water volume and to pro- vide proper dosing. Therefore, ultrasonic flowmeter and parshall flume are to be facilitated. NNJS Consultants Co., Ltd 13-1 Bengaluru Water Supply and Sewerage Project (Phase 3) Final Report 2) Flush Mixer Flush Mixer is a facility for quick rapid agitation to uniformly diffuse the coagulant into the raw water. Using a typical flush mixer, mixing can be achieved by rotating at a proper peripheral speed. It is also possible to adjust the injection intensity by monitoring and controlling water and injection volume. 3) Flocculation Tank Flocculation tank has a function to make small flocs into larger flocs by appropriate stirring to enable them to easily sediment. When the growth of the flocs is not sufficient enough, the quality of outflow from sedimentation tank is not good with higher turbidity, or in case of the reduction of the filtration duration, suspended matter flows out with the filtered water. 4) Sedimentation Tank Sedimentation tank plays a role to separate and remove majority of the flocs formed in flocculation tank by sedimentation through gravity. In managing the sedimentation tank, it is necessary to pay special attention to water quality of outflow from the sedimentation tank, and therefore it is important that a target turbidity level is set for the outflow from sedimentation tank and water quality be monitored. The jar test should be carried out and appropriate chemical injection and equipment operation should be made based on the test result. Sludge withdraw from sedimentation tank should be monitored periodically. 5) Rapid Sand Filter Filtration tank has a function to remove the contaminants from outflow of sedimentation tank by filtration. Washing of the sand filter shall be carried out, when the head loss reaches to a set value. Washing is per- formed providing a combination of backwashing and surface washing. 6) Clear Water Reservoir Clear water reservoir is used to store treated water to take care of imbalance between the filtered water volume and water supply volume. Regular inspection of clear water reservoir is essentially required in terms of quality and hygiene. 7) Chemical Dosing Facility a) Alum Dosing Flocculants are used in the treatment process to facilitate formation of flocs and easy sedimentation of colloidal particles in the raw water. It is important to ensure an optimum injection rate and injection volume considering the quality and quantity of the raw water. Therefore, these parameters should be accurately measured, for which chemical injection equipment shall be properly maintained. Inspection and cleaning of the injection pipe should also be carried out regularly to avoid clogging of injection pipe by coagulant. In order to achieve the optimum effect of the flocculants, it is important to adjust the injection amount and agitation conditions. NJS Consultants Co., Ltd 13-2 Bengaluru Water Supply and Sewerage Project (Phase 3) Final Report b) Chlorination Disinfection is necessary for the purpose of keeping the distributed water safe. Using chlorine as a disin- fectant, a large amount of water can be easily disinfected with a longer effectiveness. 8) Sludge treatment facility Back washed water and sludge from sedimentation tanks is collected either to balancing tanks, thickeners and centrifuges to separate solids from the liquid. The liquid is sent to raw water inflow channel for the treatment again. Generated sludge is disposed of in the BWSSB property. 9) Monitoring Raw water and treated water quality are examined and reported. The monitoring items and their frequen- cy are presented in Section 14.9.2, Chapter 14. Flow and operation conditions are monitored and recorded by SCADA system. (3) Water Transmission Facilities 1) Transmission Pump and Pipeline Treated water is transmitted through 70 km length of pipeline by means of three (3) staged pumping facil- ities. Pump units are operated using a daily average flow rate to fill the GLRs in Bengaluru city. To main- tain a proper operation of pumping facilities, pump conditions are monitored and recorded by SCADA system. As a countermeasure against the failure of power supply, surge vessels and/or surge tanks are in- stalled to avoid damage by water hammer. These facilities shall be properly maintained for the sound op- eration. 2) City Trunk Main and GLRs It is necessary to maintain appropriate water level at GLRs and to ensure residual chlorine. The flow rates at the Inlet and outlet of GLRs and their water levels are monitored and recorded by SCADA system. (4) Maintenance and Repair of Equipment 1) Daily/weekly inspection Daily/ weekly inspection of the equipment is practiced including investigations, confirmation and record- ing of operating conditions of the equipment. It is necessary to analyze the differences comparing with the previous inspection results and evaluate whether or not the value matches to the standard value using the check sheet. 2) Periodical Maintenance In case if any specific equipment indicates error in its original function during ordinary and periodic in- spection, precise inspection and maintenance work should be carried out by skilled person having required expertise and knowledge. In particular, for large pumps and special equipment, the inspection shall be carried out by the manufacturer or its agents. Monitoring and Control of Water Supply System shall be undertaken in use of SCADA system. NJS Consultants Co., Ltd 13-3 Bengaluru Water Supply and Sewerage Project (Phase 3) Final Report 13.2.2 O&M Cost for the Facilities Provided by Stage V Project O&M cost is estimated including staff salary, ppower cost, chemical cost and repair cost, as shown below. For financial study, price escalation is considered setting the base year 2017. (1) Personnel Cost 1) WTP Number of O&M staff for the WTP is estimated referring to the plan employed iin Stage IV Phase 2 as shown in Table 13.2.1. Table 13.2.1 Numbber of O&M Staff at the WTP No Designation Qualification Experience Shift-1 Shift- 2 Shift-3 Nos. 1 Plaannt Manager Graduate Engineer (Civil 10 years General shhift 1 / Env.) 2 Plant Supervisor Graduate Engineer-Mech.5 years 1 1 1 3 /Elec./ Instrumentation 3 Shift-in-charge Diploma (Elec./Mech.) 3 years 1 1 1 3 (2 Elec., 1Mech.) 4 Electrician ITI (Elec.) 3 years 1 1 1 3 5 Chemist B. Sc-Chemistry 3 years 1 1 6 Laab Assistant Diploma in Lab Tech. 2 years 1 - - 1 7 Helpers 8th pass - 4 3 3 10 8 Security Guards 8th pass 2 years 2 2 2 6 9 Gardener 8th pass 2 years 2 - - 2 Total 13 7 7 30 Source: JICA Survey Team 2) Pump Station and Clear Water Reservoir Number of O&M staff at a pump station is estimated referring to the plan in Stage IV Phase 2, as shown in Table 13.2.2. Table 13.2.2 Numberr of O&M Staff at a Pump Station No Designation Qualification Experience Shift-1 Shift-2 Shift-3 Nos. 1 Plant Supervi- Graduate Engineer 10 years General shift 1 sor (Mech./Elec.) 2 Shift-in-charge Graduate (Elec./Mech.) 5 years 1 1 1 3 or Diploma (Elec./Mech.) 10 years 3 Electrician ITI (Elec.) 5 years 1 1 1 3 4 Helpers 8th pass - 4 3 3 10 5 Security Guards 8th pass 3 years 2 2 2 6 6 Gardener 8th pass 5 years 2 2 - 2 Total 10 9 9 25 Source: JICA Survey Team 3) GLR Number of O&M staff for a GLR is estimated aas shown in Table 13.2.3.