OPTIONS FOR MUNICIPAL WATER SUPPLY
The present policy of Govt. of Maharashtra and in turn of MJP is to execute and hand over the schemes to local bodies, for operation and maintenance i.e. urban schemes are handed over to MC and corporation, while rural schemes are handed over to GP and ZP. The demand for scheme is received from the local body and at that time they liberally resolve for raising and repayment of loans required, for the scheme. The Water Supply schemes are entitled for GIA of 25%, 40%, 50% and 90% respectively for Municipal schemes respectively for A class/Corporation, B class and C class. C class Municipal councils with less than 20,000 population are entitled for 100% GIA till recent past, which is now decreased to 90%. In addition, the present policy is to give 100% grant in aid for the cost of pipe lines beyond 3km/5km/8km respectively for C class MC, B class MC, A class councils/corporation. The LPCD considered till recent pas was quite liberal and design period was 30 years. This lead to administrative approval of large size municipal water supply schemes with distant sources. Normally, this source being irrigation dams and proposed under reliability considerations. The MC/Corporation chose to demand for such size schemes and also used to resolve and accept liberally for raising and repayment of loans for these big sized schemes for pleasing/impressing people by showing that they have succeeded in bagging the water supply scheme for their town with large amount of GIA.
Most of these schemes are already under execution and are at various stages of progress. Now it is being seriously thought that these schemes are not economically viable, in view of present financial status of MC. Due to poor water rates and por recovery by local bodies, the loans raised by these MC through MJP are not returned by them and most of them are in heavy financial arrears with MJP. For resolving this situation following administrative, financial, technical, steps are considered to be efficient.
The CPHEEO manual is presently specifying a uniform rate of 70 LPCD should be considered for calculation of demand for town of all sizes. Even it says that 30% population which is sufficient. These things put together the water rate comes to 61 LPCD for total population. CPHEEO manual says that additional demand for school, colleges, hostels, picture halls, offices, hospitals, lodges hotels, building under construction should be considered. Calculation of demand for these amenities is normally forgotten by consultants while framing Water Supply schemes, being difficult to compute and the scheme gets framed to 61 LPCD Water Supply which is obviously very low, especially for the town with 50 thousand population or more. It is furthering more difficult to project demand for the year at the end of design period for these amenities. The design criteria of 30 years are correct and should not be considered for reduction. So as to avoid duplication of lines from distant sources in a short period. It is worth while to note that capacity of pipeline increase in proportion to cross sectional area of the pipeline (D) 2 while the cost increases in proportion with the diameter. So obviously maintenance of two lines is much costlier.
Recent policy changes indicate that small size schemes are more economical and can be better handled by the lower class municipal councils. If the nearby source is sufficient for demand of 10-15 years then only the size of the scheme should be reduced, suiting to the availability of water all that source. In short once we had gone to an extreme end of large sized scheme and now going to the another extreme end to small scheme, need to be avoided.
In urban distribution system the residual heads are normally specified as 12 m as 17 m, while the ESR staging of old ESR’s is around 14 m and there is a temptation of providing another ESR with the same staging. If the tail end is flat or nearing flat, and the available heads from LSL of reservoir to negotiate with frictional losses is very less. Normally the designs are being done with use of computers and these designs do not show the velocity in the pipelines, which ultimately leads to the choosing of unduly higher diameters. This leads to increase pipe volume, which further leads to more unequal distribution due to quicker emptying of ESR. The appropriate solution is to increase the staging height of ESR and choose it at Proper location.
If a distribution system is designed with 61 lpcd especially where the population is already enjoying 80 lpcd or more and is claiming for scarcity of water due to unequal distribution in the system then the actual distribution is likely to be in range of 40 to 80 lpcd for the town with fair topography. For the town with unfavourable topography the actual distribution of water may be something like 30 to 80 lpcd. When the size of the town increases beyond 50,000 the actual distribution of water becomes further more unequal and such distribution leads to discontents and which leads to decrease in willingness to pay and eventually to poor recovery. On paper the scheme gets 61 lpcd while the scheme has failed.
The ward wise forecast of population for the design year is not rationally done in most of the cases. If the increase in population is accepted to be 2.5 times in 30 years, then population of wards in core area will not increase by 2.5 times and may increase by 0 to 50% while the population in the wards at the periphery will increase more than 2.5 times. Non consideration of this aspect leads to unduly large diameters in the core area and unduly small diameters at the periphery. This leads to demand of laying fresh lines from ESR and non laying of them leads to availability of less lpcd at the expanding ends.
Presently providing of meters is avoided on the grounds of cost of repairs, reading, billing. By tapping of sources at longer distance the cost of wasted water is increasing and hence the policy of metering needs to be reviewed. Metering is the effective method for computing unaccounted water and eventually for its reduction. The level of service can be more rationally ascertained because the acceptation of the users in terms of lpcd is very high, while Municipal Corporations/Government wants to supply less lpcd for restricting present investment. Once the repair of the meters, maintenance of the spare parts were big issues, but with present general advancement in technology, these issues needs re-evaluation.
Now a days agencies which can provide, maintain, read the meters and generate bills are available, and need to be encouraged. The feeling of Municipal Council is to hand over the complete system to such agencies who can maintain and repair the system including collection of revenue. This is not practicable because of present poor water rates, improper design of available distribution system, heavy subsidy from other sources of Muicipal Councils, to water supply and large strength of employees with higher pay scales. Instead of attitude of getting rid of total activity, the present maintaining agency has to take a rational view of entering in contract with such manufacturing agencies for only providing, maintaining and reading meters with generation of bills for a sizable period of 5 years, while the collection shall be retained with the Municipal Councils. This will ensure more equitable water supply and more increase willingness to pay, so that Municipal council can increase the water rates annually, decreasing cross subsidy and making the scheme self sufficient in a reasonable period of 2 to 3 years. The desire of making the scheme instantly self sufficient, leads to never making of scheme self sufficient.
If we want to hand over a scheme to private agency including collection then it is necessary to give option to the agency for choosing the required numbers of employees with a right to reject notorious employees. In short transferring of employees as per seniority is not a proper solution. So also the agency should have a right to depart with few employees whom they considered to be inefficient or notorious, even after entering in the agreement.
The contract should have a provision of making payments for the service rendered by them, while the revenue collected by agency shall be deposited with Municipal Council on day to day basis.
Alternatively the distribution of an individual ESR of a city be isolated and given on maintenance contract, where the meters of specified make are purchased and provided by the consumer and the contracting agency is required to maintain distribution system along with repairs of meters with or without collection of revenue. The contract has to charge to consumers for the repairs of meters, for which a schedule shall be made available. Only 3 or 4 makes of water meters with model numbers should be specified, so that repairing becomes easy. The maintenance contract of distribution system can have various items of repairs for a better control of service level, and removing risk factor to the contract. It should also have appropriate penal clauses to reduce the repair timings.
ZONING OF DISTRIBUTION SYSTEM
Distribution network is available for any city is required to be presented on the map of a proper scale. All storages are required to be shown on the map. All levels are also required on the map. Contours will give better idea of the possible pressures in the system.
Distribution system can be old one. After a period there can be addition to the system in the same area or it can be newly developed area. Age of the pipelines reduces the C-value of pipe material and hence the carrying capacity. With the increase in demand number of connections on old lines becomes more than its capacity. This reduces the pressures in the system. Consumers try to get accustomed to the changing situation but somehow dissatisfaction amongst the consumers begin to build up.
Dissatisfaction of consumers reflects in two ways,
a) Delaying or non-paying tendency
b) Yielding maximum water from the connection by tapping at lower levels.
In any case the system suffers. It may receive lesser revenues and also it becomes prone to pollution externally.
Improvements in the system are possible. But these improvements are cost intensive. Financially local bodies are weak and contributing for improvements is not easy for them and hence administratively it is difficult to sanction the improvements scheme.
To some extent, this difficulty can be solved, by resorting to zoning. New construction of ESR is not possible, but a pipeline can be laid directly from existing ESR to the required are without any tapping and can be directly connected to the main line of that area. In turn this line serves the purpose of construction of new ESR in that area. Pressures get improved and Consumers are benefited.
Zone of influence of any ESR
Let, R be the radius of zone with ESR as center.
At all the points on the circumference there is a required pressures say, 12 m for two story habitations.
Let maximum head loss upto the circumference be hf.
Height of ESR should be 12+hf. = H
Assume, that connections start from D m from center of ESR Then zone of influence is 0.785* (R^2-D^2)
Assume head loss in the system as 4 m / km.
For 2 km, hf = 2*4 = 8m
H = 12+8 = 20m
R = 2+D = 2 + 0.3 = 2.3 km. Assuming D = 0.3 km,
Zone of influence = 0.785* (2.3*2.3-0.3*0.3) = 0.785*5.2 = 4.082 sqkm
Zone of influence can be increased by increasing D by laying feeder main starting from the ESR directly. This becomes easy when the ESR has been provided with additional outlet for the future. Increased zone of influence can be catered differed timings. With old systems effective R will be lessened after a long time. In such cases multioutlet systems can work better with arrangement of overlapping zones of influences.
When demand is increased ESR level gets depleted rapidly. Rate of inflow proves to be less than rate of flow outgoing. This indicates higher peak factors are operating. Duration of flow of water through ESR reduces as far as effective operation is concerned. As flow of water will still continue but the level of water in the tank will not be maintained in the tank itself. This is an indication of depressurization in the system. It also indicates that the lines downstream are not running full. In this case immediate control should be to control the main valves and control the branches which are dragging water more by virtue of their levels.
Improvements with use of booster pumps, shafts and master pieces
Improvements can be done by adopting booster pumping. It uses the same quantity of water but it is further energized by using pumps. Consumers are satisfied with the increase in pressure.
Boosters can used in the form external source such as borewells or tubewells and direct pumping into the system. External water quantity may be very low compared to distribution flow, but it increases the pressure very effectively.
It is convenient to think of erecting a shaft of appropriate diameter and height in the system for getting a better control of pressures. The shaft can get water either externally or it may get water from the existing ESR through a separate feeder. External supply can be using pumps on the bore well or tube wells.
Conceptually shaft is nothing but an ESR operating with its lowest water level in the outlet pipe and not in the container. Incoming water is equal to outgoing. In the shaft there is central pipe having a small diameter than the outer pipe having a comparatively bigger diameter designed to carry the demand flow of the zone of influence. Both the concentric pipes shall be in mild steel so that the weight of shaft assembly to be erected shall be easy to handle. Shaft can be erected on a good pedestal of masonry or concrete of appropriate height. Annular space between the vertical pipes acts as a container and it can be provided with multioutlets for ensuring zoning. Pressure building characteristics are better in respect of shaft compared to ESR. Shafts are better suited where the zone to be supplied is comparatively at lower ground levels.
When the pressures in the distribution system are low and time duration of supply is also comparatively less low lying areas are benefited more in comparison with the higher level areas. Retained duration of water supply in the system in the lower areas is more as well as the pressures. Consumers in higher areas are aggrieved of getting less supply of water and with lesser pressures. In such cases, select the mains of higher and lower areas. For balancing the heads introduce a smaller diameter metallic pipe having a length of minimum 20 times diameter of main pipe and ensure fixity concentrically by sealing the annular space by cement mortar. This is a trial and error method and within one or two trails exact diameter of small pipe is found out. This piece of pipe is known as ‘master piece’ and it functions most satisfactorily.
The present policy of Govt. of Maharashtra and in turn of MJP is to execute and hand over the schemes to local bodies, for operation and maintenance i.e. urban schemes are handed over to MC and corporation, while rural schemes are handed over to GP and ZP. The demand for scheme is received from the local body and at that time they liberally resolve for raising and repayment of loans required, for the scheme. The Water Supply schemes are entitled for GIA of 25%, 40%, 50% and 90% respectively for Municipal schemes respectively for A class/Corporation, B class and C class. C class Municipal councils with less than 20,000 population are entitled for 100% GIA till recent past, which is now decreased to 90%. In addition, the present policy is to give 100% grant in aid for the cost of pipe lines beyond 3km/5km/8km respectively for C class MC, B class MC, A class councils/corporation. The LPCD considered till recent pas was quite liberal and design period was 30 years. This lead to administrative approval of large size municipal water supply schemes with distant sources. Normally, this source being irrigation dams and proposed under reliability considerations. The MC/Corporation chose to demand for such size schemes and also used to resolve and accept liberally for raising and repayment of loans for these big sized schemes for pleasing/impressing people by showing that they have succeeded in bagging the water supply scheme for their town with large amount of GIA.
Most of these schemes are already under execution and are at various stages of progress. Now it is being seriously thought that these schemes are not economically viable, in view of present financial status of MC. Due to poor water rates and por recovery by local bodies, the loans raised by these MC through MJP are not returned by them and most of them are in heavy financial arrears with MJP. For resolving this situation following administrative, financial, technical, steps are considered to be efficient.
The CPHEEO manual is presently specifying a uniform rate of 70 LPCD should be considered for calculation of demand for town of all sizes. Even it says that 30% population which is sufficient. These things put together the water rate comes to 61 LPCD for total population. CPHEEO manual says that additional demand for school, colleges, hostels, picture halls, offices, hospitals, lodges hotels, building under construction should be considered. Calculation of demand for these amenities is normally forgotten by consultants while framing Water Supply schemes, being difficult to compute and the scheme gets framed to 61 LPCD Water Supply which is obviously very low, especially for the town with 50 thousand population or more. It is furthering more difficult to project demand for the year at the end of design period for these amenities. The design criteria of 30 years are correct and should not be considered for reduction. So as to avoid duplication of lines from distant sources in a short period. It is worth while to note that capacity of pipeline increase in proportion to cross sectional area of the pipeline (D) 2 while the cost increases in proportion with the diameter. So obviously maintenance of two lines is much costlier.
Recent policy changes indicate that small size schemes are more economical and can be better handled by the lower class municipal councils. If the nearby source is sufficient for demand of 10-15 years then only the size of the scheme should be reduced, suiting to the availability of water all that source. In short once we had gone to an extreme end of large sized scheme and now going to the another extreme end to small scheme, need to be avoided.
In urban distribution system the residual heads are normally specified as 12 m as 17 m, while the ESR staging of old ESR’s is around 14 m and there is a temptation of providing another ESR with the same staging. If the tail end is flat or nearing flat, and the available heads from LSL of reservoir to negotiate with frictional losses is very less. Normally the designs are being done with use of computers and these designs do not show the velocity in the pipelines, which ultimately leads to the choosing of unduly higher diameters. This leads to increase pipe volume, which further leads to more unequal distribution due to quicker emptying of ESR. The appropriate solution is to increase the staging height of ESR and choose it at Proper location.
If a distribution system is designed with 61 lpcd especially where the population is already enjoying 80 lpcd or more and is claiming for scarcity of water due to unequal distribution in the system then the actual distribution is likely to be in range of 40 to 80 lpcd for the town with fair topography. For the town with unfavourable topography the actual distribution of water may be something like 30 to 80 lpcd. When the size of the town increases beyond 50,000 the actual distribution of water becomes further more unequal and such distribution leads to discontents and which leads to decrease in willingness to pay and eventually to poor recovery. On paper the scheme gets 61 lpcd while the scheme has failed.
The ward wise forecast of population for the design year is not rationally done in most of the cases. If the increase in population is accepted to be 2.5 times in 30 years, then population of wards in core area will not increase by 2.5 times and may increase by 0 to 50% while the population in the wards at the periphery will increase more than 2.5 times. Non consideration of this aspect leads to unduly large diameters in the core area and unduly small diameters at the periphery. This leads to demand of laying fresh lines from ESR and non laying of them leads to availability of less lpcd at the expanding ends.
Presently providing of meters is avoided on the grounds of cost of repairs, reading, billing. By tapping of sources at longer distance the cost of wasted water is increasing and hence the policy of metering needs to be reviewed. Metering is the effective method for computing unaccounted water and eventually for its reduction. The level of service can be more rationally ascertained because the acceptation of the users in terms of lpcd is very high, while Municipal Corporations/Government wants to supply less lpcd for restricting present investment. Once the repair of the meters, maintenance of the spare parts were big issues, but with present general advancement in technology, these issues needs re-evaluation.
Now a days agencies which can provide, maintain, read the meters and generate bills are available, and need to be encouraged. The feeling of Municipal Council is to hand over the complete system to such agencies who can maintain and repair the system including collection of revenue. This is not practicable because of present poor water rates, improper design of available distribution system, heavy subsidy from other sources of Muicipal Councils, to water supply and large strength of employees with higher pay scales. Instead of attitude of getting rid of total activity, the present maintaining agency has to take a rational view of entering in contract with such manufacturing agencies for only providing, maintaining and reading meters with generation of bills for a sizable period of 5 years, while the collection shall be retained with the Municipal Councils. This will ensure more equitable water supply and more increase willingness to pay, so that Municipal council can increase the water rates annually, decreasing cross subsidy and making the scheme self sufficient in a reasonable period of 2 to 3 years. The desire of making the scheme instantly self sufficient, leads to never making of scheme self sufficient.
If we want to hand over a scheme to private agency including collection then it is necessary to give option to the agency for choosing the required numbers of employees with a right to reject notorious employees. In short transferring of employees as per seniority is not a proper solution. So also the agency should have a right to depart with few employees whom they considered to be inefficient or notorious, even after entering in the agreement.
The contract should have a provision of making payments for the service rendered by them, while the revenue collected by agency shall be deposited with Municipal Council on day to day basis.
Alternatively the distribution of an individual ESR of a city be isolated and given on maintenance contract, where the meters of specified make are purchased and provided by the consumer and the contracting agency is required to maintain distribution system along with repairs of meters with or without collection of revenue. The contract has to charge to consumers for the repairs of meters, for which a schedule shall be made available. Only 3 or 4 makes of water meters with model numbers should be specified, so that repairing becomes easy. The maintenance contract of distribution system can have various items of repairs for a better control of service level, and removing risk factor to the contract. It should also have appropriate penal clauses to reduce the repair timings.
ZONING OF DISTRIBUTION SYSTEM
Distribution network is available for any city is required to be presented on the map of a proper scale. All storages are required to be shown on the map. All levels are also required on the map. Contours will give better idea of the possible pressures in the system.
Distribution system can be old one. After a period there can be addition to the system in the same area or it can be newly developed area. Age of the pipelines reduces the C-value of pipe material and hence the carrying capacity. With the increase in demand number of connections on old lines becomes more than its capacity. This reduces the pressures in the system. Consumers try to get accustomed to the changing situation but somehow dissatisfaction amongst the consumers begin to build up.
Dissatisfaction of consumers reflects in two ways,
a) Delaying or non-paying tendency
b) Yielding maximum water from the connection by tapping at lower levels.
In any case the system suffers. It may receive lesser revenues and also it becomes prone to pollution externally.
Improvements in the system are possible. But these improvements are cost intensive. Financially local bodies are weak and contributing for improvements is not easy for them and hence administratively it is difficult to sanction the improvements scheme.
To some extent, this difficulty can be solved, by resorting to zoning. New construction of ESR is not possible, but a pipeline can be laid directly from existing ESR to the required are without any tapping and can be directly connected to the main line of that area. In turn this line serves the purpose of construction of new ESR in that area. Pressures get improved and Consumers are benefited.
Zone of influence of any ESR
Let, R be the radius of zone with ESR as center.
At all the points on the circumference there is a required pressures say, 12 m for two story habitations.
Let maximum head loss upto the circumference be hf.
Height of ESR should be 12+hf. = H
Assume, that connections start from D m from center of ESR Then zone of influence is 0.785* (R^2-D^2)
Assume head loss in the system as 4 m / km.
For 2 km, hf = 2*4 = 8m
H = 12+8 = 20m
R = 2+D = 2 + 0.3 = 2.3 km. Assuming D = 0.3 km,
Zone of influence = 0.785* (2.3*2.3-0.3*0.3) = 0.785*5.2 = 4.082 sqkm
Zone of influence can be increased by increasing D by laying feeder main starting from the ESR directly. This becomes easy when the ESR has been provided with additional outlet for the future. Increased zone of influence can be catered differed timings. With old systems effective R will be lessened after a long time. In such cases multioutlet systems can work better with arrangement of overlapping zones of influences.
When demand is increased ESR level gets depleted rapidly. Rate of inflow proves to be less than rate of flow outgoing. This indicates higher peak factors are operating. Duration of flow of water through ESR reduces as far as effective operation is concerned. As flow of water will still continue but the level of water in the tank will not be maintained in the tank itself. This is an indication of depressurization in the system. It also indicates that the lines downstream are not running full. In this case immediate control should be to control the main valves and control the branches which are dragging water more by virtue of their levels.
Improvements with use of booster pumps, shafts and master pieces
Improvements can be done by adopting booster pumping. It uses the same quantity of water but it is further energized by using pumps. Consumers are satisfied with the increase in pressure.
Boosters can used in the form external source such as borewells or tubewells and direct pumping into the system. External water quantity may be very low compared to distribution flow, but it increases the pressure very effectively.
It is convenient to think of erecting a shaft of appropriate diameter and height in the system for getting a better control of pressures. The shaft can get water either externally or it may get water from the existing ESR through a separate feeder. External supply can be using pumps on the bore well or tube wells.
Conceptually shaft is nothing but an ESR operating with its lowest water level in the outlet pipe and not in the container. Incoming water is equal to outgoing. In the shaft there is central pipe having a small diameter than the outer pipe having a comparatively bigger diameter designed to carry the demand flow of the zone of influence. Both the concentric pipes shall be in mild steel so that the weight of shaft assembly to be erected shall be easy to handle. Shaft can be erected on a good pedestal of masonry or concrete of appropriate height. Annular space between the vertical pipes acts as a container and it can be provided with multioutlets for ensuring zoning. Pressure building characteristics are better in respect of shaft compared to ESR. Shafts are better suited where the zone to be supplied is comparatively at lower ground levels.
When the pressures in the distribution system are low and time duration of supply is also comparatively less low lying areas are benefited more in comparison with the higher level areas. Retained duration of water supply in the system in the lower areas is more as well as the pressures. Consumers in higher areas are aggrieved of getting less supply of water and with lesser pressures. In such cases, select the mains of higher and lower areas. For balancing the heads introduce a smaller diameter metallic pipe having a length of minimum 20 times diameter of main pipe and ensure fixity concentrically by sealing the annular space by cement mortar. This is a trial and error method and within one or two trails exact diameter of small pipe is found out. This piece of pipe is known as ‘master piece’ and it functions most satisfactorily.
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