DFID ENGINEERING THEME W4 SUMMARY

R5478:

Cost-effectiveness of monitoring and maintenance options associated with groundwater abstraction


Dates:   1993
Author/s: Dr Peter Howsam
Phone: 01525 863288 Contact: Water Management Group
Silsoe College
Cranfield University
Silsoe, MK45 4DT, UK
Fax: 01525 863300
E-mail: P.Howsam@cranfield.ac.uk
URL: http://www.silsoe.cranfield.ac.uk/

Summary

Background

The importance of proper monitoring and maintenance of water supply boreholes and irrigation
tubewells was highlighted during an ODA sponsored project, international survey and conference
held in 1990. (ODA projects R4428/R4582/D044). This trend has been reinforced by the UK and
USA water industries' recent decisions to commission the preparation of guide-lines for the
development of practically and economically sound borehole monitoring and diagnosis, operation
and maintenance, and rehabilitation, strategies.

Many Third World countries depend on potable water and irrigation water supplies from
groundwater resources via boreholes/tubewells. Yet with inadequate or inappropriate monitoring
and maintenance too many of these wells operate inefficiently or have been abandoned.
Rehabilitation if attempted was often on a `suck-it-and-see' basis and frequently failed. While
such a situation exists in many parts of the developed world also, it must be regarded as
particularly serious in developing countries where weak economies could well do without the
added strain of supporting inefficient systems or where failure can simply mean going without.
Cost effective, functional and sustainable groundwater abstraction strategies need to be
established. It is believed that money spent in the establishment of such practices will be repaid
many times over in terms of savings in annual groundwater pumping costs and in capital
replacement costs. The human benefits in terms of social needs, health and food production are
of even greater proportions.

Whilst many developing countries themselves recognise the weakness in their groundwater
abstraction strategies, they often do not have the resources to change. It is not only finance that is
required. Institutions and infrastructure need to be in place. To help establish and then run these,
training in technology and management is also required. At each stage and in each component
the cost effectiveness of the measures proposed needs to be assessed. This is important for both
international aid agencies in supporting projects and national governments in the prudent
allocation of scarce funds.

Experience suggests that whilst cost-benefit analysis is widely talked about and is being
increasingly applied, application to specific disciplines requires considerable input to establish the
scope of a system, its consequences and the key economic factors. It would not be practical or
good use of resources if every organisation had to go through the same development stages.

Objectives

Immediate

A project report in which the methodology is presented and explained.

Intermediate

A report on the developed methodology which is widely disseminated.
The rapid acceptance and utilisation of the developed methodology.

Wider objectives

The establishment of practically and economically sound and integrated management strategies
for groundwater abstraction systems.

leading to:

More efficient and reliable water supplies from boreholes, with reduced operating costs and
reduced demand for capital /replacement projects.

and with:

Benefits passed onto public health, agriculture and food production.

Methodology

A methodology has been developed from an evaluation of groundwater engineering experience,
from a review of technical, economic and management literature and from consultations with
potential users in the UK and overseas. General features of the methodology defined at the outset
were that, for it to be readily usable and useful, it had to be:

  • relatively simple and easy to apply by a range of professional disciplines;
  • flexible in relation to the wide range of hydrogeological and groundwater engineering
    circumstances likely to be encountered;
  • flexible in relation to the amount and quality of data available;
  • flexible in relation to the users needs and circumstances

There are two main steps in the assessment of the cost-effectiveness of m & m. These are an
internal technical/monetary assessment, concerning the management of the groundwater
abstraction system itself, and external factors relating to water use, water users and the
environment in which water abstraction is taking place.

The method makes two basic assumptions:

(i) that there are three main components which are important in the assessment of cost effectiveness - these are costs of management options,frequencies with which costs are incurred and well performance over time;

(ii) that effective m & m fulfills its objective of the maintenance of a standard of service and that the costs are incurred in doing so.

The approach taken in the development of the method, assumes that increasing levels of
monitoring enable, firstly and most importantly, well performance to be analysed, then well
condition to be assessed, and then the process causing well condition to be identified. As a result
of monitoring, appropriate maintenance strategies may then be selected. Each element of the
approach is described below.

  1. The internal assessment allows for m & m to be assessed for several classifications of well,
    i.e. for different aquifer, well and pump types. This recognises that some classifications will
    regularly present less operation and maintenance problems than others.
  2. Monitoring enables the performance of the well system to be assessed, early indicators of any
    deterioration in performance to be identified, and where appropriate the need for early
    corrective maintenance to be identified. The monitoring of well performance is the primary and
    simplest level of monitoring.
  3. Once a decline in well performance has been diagnosed, monitoring enables the condition of
    the components of the groundwater abstraction system to be assessed in order to identify the
    extent and location of the problem within the abstraction system. Corrective maintenance may
    then be carried out.
  4. A comprehensive level of m & m allows processes which cause deterioration in well
    component condition and well performance to be identified and appropriate preventative
    maintenance to be carried out to reduce the impact of the processes upon future well
    performance.
  5. Through analysis of the information gained, monitoring enables the use of risk assessment
    techniques, which estimate the risk of deterioration of well performance or well component
    failures for given aquifer characteristics and well components. The principle of risk
    assessment is one that has been developed in the evaluation of maintenance schedules for
    water delivery systems and in other supply industries.
  6. The analysis of performance, condition, and process for different classifications of well may
    enable modifications to the design, construction (including material selection) and
    management of future groundwater abstraction systems to be made.
  7. Whilst given strategies for m & m will produce benefits such as those shown above, there will
    be associated monetary costs attached to them. A m & m strategy will incur additional costs
    but is also likely to lead to savings due to a reduction in the frequency of other costs, such as
    those for well rehabilitation, pump replacement and emergency action following well failure.
    Therefore, different strategies will have different costs and benefits reflecting differences in
    frequency of occurrence, well operation and other well management events.

The assessment of cost-effectiveness can be carried out in two ways. One is to take into account
only the anticipated costs 'with' and 'without' m & m (or for different levels of m & m), in order to
show simply whether it is more or less expensive to monitor and maintain than not to (or which is
the cheaper of two different m & m strategies). This level of assessment implies a change in the
performance of the well through the changes in frequency with which costs of other well
management events are incurred (such as well rehabilitation or pump replacement). It does not
take directly into account the actual performance of the well. Therefore, another way is to relate
the costs of well management to well performance for 'with' and 'without' m & m (or for different
levels of maintenance).

The internal assessment examines only the direct monetary costs and benefits of alternative m &
m strategies for groundwater abstraction systems. The benefits of a higher level of m & m are a
sustained well performance level and a reduction in the risk of system failure and the related
costs of disruption, emergency response and premature capital replacement. The outcome of the
internal assessment is an estimate of net present value of the m & m strategy. However, this
estimate is likely to represent only a minimum order of the value of m & m. In many situations the
estimate of m & m benefits is likely to undervalue the benefit to users, suppliers and regulators of
a reliable, safe, and resource-efficient system. For example, the internal assessment recognises
that system failure may result in extra costs of emergency supplies. The impact on user welfare
of a disrupted and unpredictable water supply, however, is not included in the internal
assessment. In some cases, these users may be farmers or manufacturers who suffer loss of
production as a result of unreliability in supply.

For this reason, an external assessment is included, which reflects the environment in which the
groundwater system operates. This assessment recognises that agents (users or suppliers) may
derive benefits (and costs) over and above those which can be measured in monetary values,
and that these agents may be willing to commit extra capital and recurrent expenditure in order to
secure these non-monetary, less tangible, benefits.

The external assessment is compatible with the principle of a 'predefined standard of service'. For
example, water of a specified quality should be made available to users of a given type in given
quantities with a given probability of uninterrupted supply. Where such standards have been
specified, the best strategy for m & m is that which delivers the standards of service at minimum
cost. In many cases, however, standards of service are not adequately defined and they are a
variable in the formulation of a water supply (and m & m) strategy.

Furthermore, the standards of service are likely to vary according to local circumstances and
practices, which are socially, economically and politically defined. The external assessment
attempts to elicit implied, locally relevant standards of service, and thereby the extent to which the
satisfaction of these could be used to justify part, or indeed all, of the additional costs of m & m.

The elements included in the external assessment are:

  • User Category
  • User Population
  • User Confidence
  • Alternative sources
  • Environmental Impacts

It is recognised that these external factors are important in the formulation of an appropriate m &
m strategy and that decision criteria should extend beyond cost benefit to include elements of
standards of service. In broad terms, this requires water suppliers, preferably as a result of
consultation, to determine the proportion of m & m costs which should be offset against
particular standards of service. In most cases, this will have the effect of reducing the level of extra costs of m & m, thereby increasing the benefit:cost ratio and the perceived value-added of m & m.

Use and users

The method is appropriate for people who are closely involved with the day-to-day management
of groundwater abstraction systems, for people who are involved in the planning and
implementation of water supply systems and for those who are involved at the project feasibility
and financing level.

It is anticipated that there will be three main types of user:

(i) Well management or monitoring/maintenance organisations or individuals with adequate
data who will be able to fully utilise the method.

(ii) Well management or monitoring/maintenance organisations or individuals with inadequate
data who can use the method to gain crude estimates of the likely costs and benefits of
various options. These first indicators may well often demonstrate the need for a m & m
strategy and initiate monitoring and data collection. In this respect attempts have been made
to provide guidance on data needs, sources, collection and compilation.

(iii) Planners who wish to evaluate all aspects of current or potential groundwater resource
development/supply projects.

Following consultations with potential users of the method, initial thoughts that lack of detailed
data may be a concern were confirmed. Therefore, two versions of the method have been
developed. One considers detailed cost and well performance data and one offers assistance to
users in the selection and definition of data for analysis.

The method has been developed on Lotus 123 spreadsheets so that it may be compatible with
most other spreadsheets used world-wide. In all cases the user goes through a three stage
process: guided data input to a structured spreadsheet file, selected data analysis and a choice of
result presentation.

The proposed method is designed so that it can be used as either a stand-alone tool or as part of
an integrated water management system. It is intended to be flexible so that not only m & m
strategies may be assessed but also that any groundwater abstraction option (such as pumping
regimes) may be analysed for cost-effectiveness.

The approach is more suitable to deep wells, with motorised pumps, than to shallow wells which
use hand pumps. The method may be used for the latter case, although the emphasis of the
analysis will be upon the costs 'with' and 'without' maintenance, since the issue of well
performance and, hence, operating costs is much less crucial.

Future action

Immediate

This report has been circulated to 50 organisations both in the UK and overseas for evaluation.

Intermediate

It is proposed that a second phase to this project should be a full and detailed trial application and
adaption where necessary of the proposed methodology by appropriate organisations. In the UK
it is hoped that several of the major water plc's which have significant numbers boreholes will
undertake a full cost-benefit analysis of alternative monitoring and maintenance strategies, using
the prepared methodology. In developing countries it is hoped that the development of monitoring
and maintenance strategies could form part of existing or new groundwater projects and
developments, in which the cost-effectiveness/benefit evaluation of alternative strategies would
be an important component.

We would be pleased to hear from any organisation or agency in the process of reviewing an
existing or developing/planning to develop a new, monitoring and maintenance strategy for
groundwater abstraction systems, where they think that this work could make a useful
contribution.

The project work is summarised in the following paper:

Sutherland, D C, Howsam, P and Morris, J (1996). Cost-effective monitoring and maintenance
strategies for groundwater abstraction
. Journal of Water Supply, Research and Technology -AQUA,
45 (2), 49-56.


E-mail comments to the webmaster
Copyright © 1999 WELL