Lecture3

Model Answers to Learning Activities

LEARNING ACTIVITY 3.1

Bangalore Mahanagara Palike (BMP) undertakes the waste collection system in our locality.

Solid waste collection starts at the point of waste generation. Wastes are stored in bottomless

concrete containers placed 100 meters apart for which covers are not provided. Wastes are

collected in trucks of 4 to 5 tonnes capacity. Collection frequency is based on the requirement of

the locality. Since our locality is mostly residential, collection of waste is done three times a

week. The collection crew consists of a driver and two helpers. The collection route for our

locality is entirely left to the drivers judgement.

Collection is often the most costly component of the solid waste management system and a

proper collection system design and management can reduce the cost significantly. In terms of

cost, the collection system in developing countries accounts for 70 80% of the total budget for

solid waste management, the remaining 20 30% going for overheads. While making decisions

for alternative collection systems, the services must be evaluated considering such factors as

efficiency, effectiveness, equity, reliability, safety and environmental impacts.

LEARNING ACTIVITY 3.2

The types of containers used in our locality are uncovered bottomless concrete rings having 0.9

meters diameter and 0.6 cubic meter storage capacity. They are placed 100 200 meters apart.

The collection vehicle used is a truck of 4 5 tonne capacity and is enclosed by an iron mesh at

the top to prevent the spillage of wastes.

LEARNING ACTIVITY 3.3

The heuristic (trial and error) route development process is a relatively manual approach that

applies specific routing patterns to block configurations. Routes are to be traced on the tracing

paper by following certain rules. Routes should not be fragmented or overlapping. Each route

should be compact, consisting of street segments clustered in the same geographical area. In

streets with heavy traffic, wastes should not be collected during peak hours. Higher elevations

should be at the start of the route. Waste on a steep hill should be collected, when practical, on

both sides of the street while vehicle is moving downhill. This facilitates safe, easy and fast

collection. In case of one-way streets, it is best to start near the upper end of the street, working

down it through the looping process. Services on dead end streets can be considered as

services on the street segment. To keep right turns at a minimum, collect the dead-end streets

when they are to the left of the truck. They must be collected by walking down, backing down or

making a U-turn.

LEARNING ACTIVITY 3.4

Transfer station is a centralised facility where waste is unloaded from smaller collection vehicles

and reloaded into large vehicles for transport to a disposal or processing site. To determine

whether a transfer system is viable for a particular community, the decision-makers should

compare the costs and savings associated with the construction and operation of a transfer

facility. The use of transfer station is a sound practice when there is a need for vehicles

servicing a collection route to travel a shorter distance, unload and return quickly to their primary

task of collecting the waste. There are 3 types of stations depending on the capacity, viz., small

capacity (less than 100 tonnes/day), medium capacity (100 to 500 tonnes) and large capacity

(more than 500 tonnes). Some of the factors that should be considered in determining the

appropriate size of a transfer facility include the capacity of collection vehicles, time required to

unload, waste sorting, hours of station operation and time required to connect and disconnect

the trailers from compactors.

LEARNING ACTIVITY 3.5

Convert 400 kg/m3 to tonnes, i.e. 400/1000 = 0.4 tonnes/m3

(i) Number of services/vehicle load (N)

N = (C X D)/W

= (12 x 0.4)/2

= 2.4 ~ 2

(ii) Time required to collect the load

E = N x L

= 2 x 2

= 4 minutes

LEARNING ACTIVITY 3.6

The solid waste collection in our ward is undertaken by a private contract system, and

Bangalore Mahanagara Palike (BMP), which has appointed a Medical Health officer, a Senior

Health Inspector, a Junior Health Inspector and Sanitary Daffedars, assists the private

contractor. They have employed pourakarmikas for sweeping and collection of wastes from

households and containers. The Health Inspectors are in charge of the muster roll. Workers

assemble at 6:30 a.m. in the morning at a specified place. Each worker is given the equipment

and the section of the ward, which he or she has to clean. Work ends at 10:30 a.m. and the

workers assemble at the same place to give their muster roll. From 11 a.m. to 1:30 p.m. gang

work is carried out in a particular area or even a whole ward depending on the need. The need

may be a clogged drain or clearing of black spots. The attendance of each of the workers is

recorded at the field by the inspectors. There is another muster roll at 1:30 p.m. At present

records are not maintained on the quantity of wastes collected and their variation. Once in a

while, the contractor of our ward is asked to determine the quantity of waste generated per day.

LEARNING ACTIVITY 3.7

The activities responsible for successful implementation of collection and transfer systems are

as follows:

Finalising and implementing the system management plan.

Purchasing and management of equipment.

Hiring and training personnel.

Providing public information.

Monitoring system cost and performance.

LEARNING ACTIVITY 3.8

(i) If the crew can service 2 customers in one minute, then in 4 hours (i.e., 4 x 60 minutes)

the crew can service:

2

1

X

4 60

X = 480 customers per day.

(ii) The number of collection vehicles needed for a community is given by:

N

SF

XW

Where N = number of collection vehicles required; S = total number of households

serviced = 10,000; F = collection frequency, number of collections per week = 1; X =

number of households a single truck can service per day = 4 and W = number of workers

per week = 250.

Therefore N

10000 1250 4

, i.e., the corporation ward requires ten collection vehicles.