Time and motion study in FSM (1) Analysis of existing FS collection system

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or cover after first desludging operation (e.g. in Vietnam)

Collection time Short Long SWM: dustbins loading

FSM: FS pumping

Number of collection points Many Few

Ending time - Rather long FSM: All tasks after pumping and

before departure of vacuum truck to discharge site Vehicle use efficiency Difficult Easy SWM: Is the vehicle loaded to

capacity?

FSM: Capacity of septic tanks more or less equal to that of vacuum trucks

Travel time (all travels during collection; does not include travel to discharge site)

Short Long SWM: Best route identified and optimized through preliminary studies

FSM: Route changing everyday;

limited loading capacity necessitating many trips to discharge site

Travel time to discharge site Long Long Discharge sites are often remotely located on the outskirts of cities

Discharge time Short Short

Table 3.1 seems to indicate that time and motion studies applied in FSM could even be more efficient than when applied to SWM. Indeed, the field study conducted in Vietnam confirmed that a larger number of motions in FS collection have an impact on efficiency in comparison to solid waste collection. It also confirmed that breaking down each desludging cycle into individual motions was a successful approach to identify the problems that negatively impact FS collection efficiency.

3.3.2 Time and motion study in FSM

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(2) Field data gathering from FS collection system

The second general objective is to gather precise field data on the existing FS collection system which will provide useful information to decision makers when planning for improvement. The global objectives (1) and (2) are similar to those of the time and motion studies conducted in SWM.

In most developing countries, FS collection lacks efficiency and with other links of the sanitation and FSM service chain that may be at fault, results in fecal sludge not being managed in a safe and sustainable manner, thus becoming a threat for public health and the environment. If the number of desludged Johkasou (PAWTPs) for individual households in Japan within a day can be as high as 13⁵, the average daily number of desludged septic tanks per vacuum truck by private operators in the cities of Hanoi and Ho Chi Min is reported to be as low as 2.7 and 1.4, respectively (Viet Anh et al., 2012).

This lack of efficiency affects profitability and, in a context where desludging tariffs are generally low, can incite hazardous practices such as open dumping particularly when the private sector operates. Although prohibited by law in some countries such as Vietnam, such inappropriate practice enables cutting the costs associated with the transport of the collected FS to a designated treatment or discharge facility, which can be time demanding if remotely located and when traffic density is high. In addition, a fee is often charged to the vacuum trucks at the treatment or disposal site, which is another factor that prevents private operators from bringing FS to these facilities.

(3) Identification of vehicle use efficiency

In SWM, the first specific objective is to know how efficiently the collection vehicles are used and working hours managed. The difference here with FSM is about the way the collection vehicles are used. In SWM the utilization efficiency of the collection vehicles depends on whether they are loaded to capacity. With FS collection in developing countries, it is often observed that the size of the collection vehicles is the same as that of the septic tanks or even smaller. Therefore the collection vehicles are used at full capacity, but the downside is that a single FS collection operation may be insufficient to fully desludge the septic tanks. As septic tank owners are predominantly not willing to pay for another FS collection trip, this leaves the unsatisfactory situation of having septic tanks not fully emptied and, hence unable to function at their best level of performance.

5 Information obtained by the author through a discussion with a Johkasou desludging vendor in Japan.

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Further to the problem of vacuum truck capacity, the number of trucks available for desludging operations may also be an issue in developing countries. Availability may be limited due to vehicle failure or to the high cost required for the acquisition of a sufficient number of trucks; the latter being an issue commonly shared with SWM. In the case of having several vacuum trucks with different tank capacities, the lack of information on the size of the septic tanks to desludge may be an issue affecting the efficiency of the FS collection system if the capacity of the vacuum trucks does not match that of the septic tanks.

Other issues may materialize even if the size of the vacuum trucks is bigger than that of the septic tanks. Most of the developing countries in which desludging services are provided use on-demand desludging. With this system, the number of septic tanks to desludge may vary from one day to another depending on the number of requests made by septic tank owners. With on-demand desludging, vacuum trucks may not be used all day if the number of requests is low. By contrast, scheduled desludging is a service in which the emptying of septic tanks is planned in advance and at regular intervals. In the case of Japan, the Johkasou used for households (for 5 users) are required by law (under the Johkasou Law) to be desludged once a year. Very few countries have adopted such legal requirement.

(4) Identification of working time efficiency

The second specific objective is to understand how collection workers spend their time and whether their working time is effectively used. In SWM, three ways to express the working efficiency of collection workers can be identified (Sakurai, 1990):

- Gross Man-Minutes/Ton of garbage collected: to measure the time elapsed between the departure and return to the garage;

- Net Man-Minutes/Ton of garbage collected: to measure the time used only in the collection area;

- Ton of garbage collected/Man-Day.

In FSM, it is not meaningful to compare the utilization efficiency of the collection vehicles or the time used by collection workers in different cities or areas as local conditions vary from one place to another. However, it is useful to compare the efficiency of FS collection in a same area before and after the implementation of the improvement measures developed through the time and motion study.

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(5) Identification of collection route appropriateness

The third specific objective is to assess the appropriateness of the collection route.

A compact route is to be preferred to a fragmented route. However, differently to SWM in which the same collection areas is to be covered at regular intervals, FSM collection routes cannot be planned in advance with on-demand desludging (unless all requests are made sufficiently in advance), and are consequently subject to change every day. Such system imposes the use of fragmented routes which reduce collection efficiency, especially if these routes are found to be difficult to access for a vacuum truck during the actual collection process. This situation can be improved by, whenever possible, identifying and avoiding the spots that may increase transport time, such as congested areas and u-turns; the latter being also dangerous, particularly with heavy traffic or at night.

In cities or areas with narrow streets that are difficult to access for a vacuum truck, such as what is observed in Vietnam, it is advisable to identify in advance the streets that are large enough to accommodate vacuum trucks in order to avoid parking problems and anticipate potential preparation time loss. This problem does not apply to SWM as the collection trucks only park for a fraction of seconds to load dustbins. In the case of FSM, collection and parking time is much longer and can be far more disruptive. A time and motion study can enable the identification of inappropriate or congested routes as well as streets that are too narrow. In addition, routing via the Google GPS navigation system in the covered cities or areas can provide the working crew real-time information on traffic conditions which can help avoid delays in congested areas. Furthermore, the collection route should start with the closest septic tank to desludge and end with the septic tank that is the closest to the discharge site.

Scheduled desludging, which consists of the emptying of FS from septic tanks in a pre-determined area, presents the same characteristics as solid waste collection and enables a fragmented route to be transformed into a compact route planned in advance. Such system is the best way of reducing transport time in FSM.

(6) Identification of collection time appropriateness

The fourth specific objective is to check whether the collection time is appropriate or not and if it takes into consideration factors that negatively affect collection time, such as collection work being conducted in commercial areas during rush hours. In such

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case, carrying out collection in off-peak hours would be more rational, although in some areas or cities traffic conditions may remain bad for long hours. The working crew schedule could include different shifts to cope with traffic conditions, but it may also not be flexible due to labor constraints. Under such conditions, the FS collection routing and the positioning of discharge facilities (transfer stations) in strategic locations that can be quickly reached from the desludging sites can have an important impact on the efficiency of the FS collection service.

(7) Septic tank access assessment

The fifth specific objective is to check the conditions of access of septic tanks, in or outside the house or building plot. It would also be useful to measure the size of the facilities to desldudge, which would help determine the appropriate volume of the vacuum truck to be used for FS collection. This can be checked in advance if information is collected and recorded, for example in a ledger, by the company in charge of the desludging services. In addition, a distinctive sign could be left after the first emptying for easy localization in prevision of future desludging operations. The lack of such information can greatly increase the time required for desludging, let alone the possibility of errors in the case of septic tanks built under the houses as it is done in Vietnam. Installing caps or covers for septic tank access, when constructed, would help localization and also eliminate the risk of gravel and debris entering the septic tank during breakage for access. Septic tanks are widely spread wastewater treatment facilities but many of them are difficult to access and not built according to local standards or code, when existing. Gathering and recording data on their location and condition is an important step for the development of efficient FS collection services.

(8) Crew behavior study

The sixth specific objective is to understand how behaves the crew. This objective, which applies to both SWM and FSM, is particularly important to reduce the risks of accident by identifying unsafe behavior from collection workers.

To reduce the risk of accidents or health problems related to work for the crew members, it is particularly important to see how they collaborate together, identify unsafe behavior on the road (respect of speed limits, road signs and traffic signalization), and check whether the collection workers conduct their work in a safe manner not prone to accidents and with the right equipment to prevent hygiene

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problems or injuries (e.g. as shown in Figure 3.2 and 3.3, appropriate shoes and gloves, daily cleaned uniform, safety equipment to secure the perimeter around the vacuum truck when needed, hand washing after each desludging operation, shower at the workplace at the end of the collection work, etc.). A focus on these issues will not only improve workers’ well-being but also reduce the total service costs, which increases with absences from work due to accidents or health issues.

Figure 3.2: Securing of the perimeter around the vacuum truck during a desludging operation

Source: Author

Figure 3.3: Appropriate working equipment with gloves and work clothes, and safety behavior with hand washing at the end of the desludging operation (left and

center). Filled out desludging form at the end of the FS collection operation (right) Source: Author

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In addition to improving safety, a crew behavior analysis can help find a more satisfying and efficient way to collect fecal sludge. Moreover, as the crew is in direct and regular contact with the service users (citizens), such study can provide a view on how they interact with them, whether they provide users sufficient and relevant information and properly conduct all administrative requirements (e.g. proper filling of the deslduging form from the crew and the users). It can help identify communication issues and establish a training that can improve the crew’s communication skill, which may ultimately result in a better relationship with the service users, more cooperation from them, more satisfaction towards the FS collection service and, accordingly, an increased willingness to pay for this service.

The following, adapted from Dr. Sakurai’s recommendations on time and motion studies in SWM, are advisable points to be checked for studying the behavior of the crew.

a. Collaboration between crew members

b. Relationship with the users (citizens), including the fulfilling of administrative requirements

c. Unsafe movements and working conditions, including health safety measures

(9) User cooperation assessment

The seventh specific objective is to evaluate the level of user cooperation. In his work, Dr. Sakurai (1990) highlights that the evaluation of user cooperation in SWM is “in areas such as the use of standardized dustbins, the setting out of dustbins in pre-established collection points according the pre-arranged time schedules, and the grade of material separation, if a separate collection system is used in the city”.

In the field of FSM, user collaboration includes all the areas that can help reduce the time of desludging operations, such as maintaining a clear and easy access to the septic tank if located outside the house, or to leave an indication that shows where is located the septic tank if built under the house as it is seen in Vietnam, or, even better, to ensure the installation of a cap or cover after the first desludging operation.

Another welcome act of collaboration could be the use of a ledger in which would be recorded all the useful information for the maintenance of the septic tank.

By contrast, a lack of user cooperation may slow down the FS collection process. Such behavior can materialize when users are reluctant to pay for FS collection when

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desludging is compulsory (as a legal requirement, for example, with scheduled desludging). This behavior has been observed in Malaysia when scheduled desludging was a legal obligation under IWK’s responsibility. IWK faced opposition from customers with repeat desludging, especially from the third visit.

3.3.3 Preparation of a time and motion study in FSM