Identifying Inter-relationships

It is important at all stages of the planning process to recognise that the facts, data and assumptions gathered or made about some part of the plan invariably influence other aspects of the total plan. Hence the likely recoverable reserves may influence or be influenced by the mining method which in turn may be influenced by the availability of manpower or fresh information o n t h e likely distribution of the reserves can be used t o check the suitability of the previously-preferred mining

Method Working Layout

/ I

Manpower

A v a i l a b i l i t y Requirements

\

.

F i g u r e 1

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Inter-relationships o f Sub-Problems

T h e recognition o f t h e s e c o n n e c t i o n s and, therefore, t h e need t o e x a m i n e c h a n g e s t o t h e t o t a l plan f r o m c h a n g e s t o o n e part o f i t , i s not

s u f f i c i e n t in itself for t h e s t r e n g t h o f t h e s e relationships should a l s o be appreciated. It may be, for instance, t h a t t h e mining and layout plan w i l l be independent o f t h e e x t e n t and d i s t r i b u t i o n o f reserves, a t least w i t h i n a fairly broad band. T h e d e p e n d e n c e o f t h e preferred mining plan o n having sufficient manpower o f t h e right s k i l l s and e x p e r i e n c e may, o n t h e o t h e r hand, be far stronger. W h e r e t h e inter-relationships a r e stronger will, o f course, vary f r o m prospect t o prospect, but their s t r e n g t h should be

identified t o understand h o w much uncertainty o r risk c a n be tolerated in e a c h part o f t h e t o t a l planning project before it a f f e c t s t h e project a s a whole. T h e n e x t s e c t i o n o f t h i s paper i s c o n c e r n e d with uncertainty, not solely w i t h i n sub-problem area, but a l s o o n how uncertainty in o n e o f t h e s e a r e a s may effect t h e o v e r a l l project.

3. T h e E f f e c t of U n c e r t a i n t y

Much o f t h e work o f the O p e r a t i o n a l Research E x e c u t i v e in t h e field of new c a p a c i t y planning h a s c o n c e n t r a t e d o n e n c o u r a g i n g t h e use o f a n a l y s i s and m o d e l s right from t h e very early s t a g e s o f planning, e v e n w h e n t h e r e is paucity o f d a t a , and t o refine a n a l y s i s a s m o r e information becomes available. T h i s m e a n s t h a t potential p r o b l e m s c a n be quickly identified but c a r r i e s w i t h it t h e d a n g e r that a s s u m p t i o n s and e s t i m a t e s , intended t o be n o m o r e t h a n that, t a k e o n a meaning which bears n o

relationship t o the crude data o n which they were based. T h e first point to make about uncertainty, therefore, is to recognise that it exists and that much of it will never be removed. Inevitably, at some point in the planning process, there will be the need to use central estimates but these should not be treated a s exactitudes, a t least not without proper understanding of the effect of s o doing.

The existence of uncertainty does not preclude effective planning,

although it does serve t o make t h e task more demanding. Indeed, it may often be the c a s e that uncertainty within particular features of the plan are of no importance and a n important task is simply t o identify where uncertainty may be more easily tolerated. Even at an early stage in planning, it is sometimes possible t o identify the important components of the plan which may constrain the plan as a whole. These constraints may be capable o f being relaxed at a cost (coal quality by spending more o n coal preparation) or fixed (total reserves) but in either case it is

important to reduce the uncertainty concerning these, since the plan a s a whole is limited by them. Figure 2 illustrates the effect of being restricted by manpower availability, and the importance, therefore, of reducing the uncertainty surrounding any estimate.

Uncertainty within o n e of these sub-problem areas and its effects o n other areas may be effectively explored through the use of simple sensitivity analysis. The model which links manpower requirements and mining strategy w a s described earlier and this c a n be used, along with other such models,

Q u a l i t y

Y

^Manpower

~ili t y

]

Requirements

Figure 2

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The Effect of Manpower Shortages

t o highlight the sensitive or critical areas of a plan. T h e example tabulated below, o n the effect o n manpower requirements of changing mining assumptions, clearly illustrates that some features of the plan such analyses, t h e Operational Research Executive have used money as the unit of measurement

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not necessarily because profitability or

field is somewhat fragmented and much work remains to be done. Studies surface exploration but large enough to cause producing c o a l faces to be halted unexpectedly, resulting in serious financial consequences. a desired output and the balance of resources between development and production. and t o test sophisticated systems of central belt and bunker control made possible by recent technological advances. that these facilities c a n cater for the likely variability in quality and quantity at the minimum cost.

4. Summary

This paper is concerned with inter-relationships and uncertainty in new capacity planning; it is not intended t o be a definitive statement of how such problems should be tackled, although it summarises some of the

approaches used by Operational Research Executive of the United Kingdom.

T h e main arguments developed are:

(i) Inter-relationships should not be ignored

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it is important to logically follow through the consequences for the plan a s a whole of making changes t o o n e part of it.

(ii) One way o f doing this is t o develop models which link sub-problem areas, and t o promote their continued use as more information becomes available.

(iii) Uncertainty is inevitable in new capacity planning, but the level of uncertainty that c a n be tolerated will not be the s a m e across all aspects of the planning strategy.

(iv) Sensitivity analysis is a simple but powerful way of identifying the consequences of different levels of uncertainty within each sub-problem and between sub-problems. Later, full risk analysis c a n be used t o assess the project as a whole.

( v ) It is important t o identify where efforts should be made t o reduce uncertainty. T h e r e is potentially a large contribution t o be made by O R Scientists and Systems Analysts in advising how this uncertainty may be most effectively reduced.

(vi) Some uncertainty is unavoidable

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o n e way of testing the robustness of the plan to the risks inherent in new capacity planning is to use simulation models to examine what insurance is necessary and what risks can be carried.

NEW MINES PLANNING AND THE ASSESSMENT OF ENVIRONMENTAL FACTORS

E.J. A l l e t t *

I n t r o d u c t i o n

I n c r e a s i n g p u b l i c awareness o f e n v i r o - m e n t a l i s s u e s h e s p u t g r e a t p r c s s x r c s on d e v e l o p e r s t o demonstrate t h a t t h e i r new n r o j e c t s a r e e n v i r o m . e c t e l l y

a c c e p t a S l e . I n t h e USA t h e r e is a s t a t u t o r y requirement on deve1ol;crs t o zeke environmental i ~ p a c t s t a t e m e n t s about any proposed nev p r o j e c t . ,F'ere zny scon be a s i n i l a r r e q u i r e n e n t f o r l u g e r o j e c t s by d e v e l o s e ~ * s i n t h e n m b e r s t a t e s

of t h e Z C . Although t h e r e is no l e g a l r e q u i r e c e n t t o do s o i n t h e VI:, t h e iYationa1 Coal 3oard (KcB) a l o n g v i t h sone o t h e r developers ~ r o d u c e a d e s c r i ; > t i o n

of t h e p o s s i b l e environmental i ~ q n c t s of n a j o r n r o j e c t z sxch as nevi mines.

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I n o r d e r t o a n t i c i p a t e and ir^ p o s s i b l e avoid enviror,mental p r o b l m s , t 5 e developer needs t o c o m i d e r t h e e n v i r o n n e n t a l f a c t o r s tnrouzh every s t a g e or^

planning a p r o j e c t . Tor example, t'ne gurpose of t h e IZ3's f e a s i j i l i t y s t u d y is t o d e c i d e whether t o groceed with the planning of a new nine. Duri-% t h i s s t u d y t h e i3oard c o n s i d e r t h e broad e n v i r o c n e n t a l c h ~ r a c t e r i s t i c s o f t h e g r o s p e c t and t i i e i r n o s s i b l e influellce on t h e p r o j e c t . 3-ftcr t h e f e a s i b i l i t y s t ~ d y , d e t a i l e d 2 l a n n i n g of t h e r o p o s e d p r o j e c t c m begin and elzviro!l:r.entai ix-i;ccts considered i n g r e a t e r d e ~ t h . ;it any s t a g e o f p l ~ ~ ~ g , d e c i s i o ~ s have t o be made which a r e i a f l u e n c e d by e n v i r o m z c t a l f a c t o r s . S t u d i e s t o he12 1;rovirle t h e answers should obviously be t a i l o r e d t o t h e p a t i c u l a r d e c i s i o n s but .they w i l l g e n e r a l l y i n v o l v e t h e f o l l o w i n g s t e p s :

*The a u t h o r i s employed i n t h e O p e r a t i o n a l R e s e a r c h E x e c u t i v e o f t h e U K ' s N a t i o n a l C o a l Board. I t must b e e m p h a s i s e d however t h a t t h e v i e w s e x p r e s s e d a r e t h o s e o f t h e a u t h o r a n d n o t n e c e s s a r i l y t h o s e o f t h e N a t i o n a l C o a l B o a r d .

1. The i d e n t i f i c a t i o n of t h c s e e n v i r o n n e n t a l i n p c t s which hzve a b e a r i x g

Indeed a l l a c t i v i t i e s can be regarded as b e i n g s > i n - o f f s from t h e f m d a s m t z l

:/e have observed t h e n t h z t t h e r e are a v a r i e t y of p r o b l e n s a s s o c i a t e d w i t h

c o u l d be nade of t h e whole p r o s p e c t by a s s u z i n g t h e n i n e t o be s i t e d i n each g r i d s q u a r e and neasur-lag t h e n o i s e impact. ? J t e r n a t i v e l y , t h e i n ? a c t c o u l d be

e s t i n a t e d by c o u n t i ~ g t h e nunber o f people v i t h i n a c e r t a i n d i s t a n c e of eack:

g r i d s q u a r e .

Zven t h i s would i n v o l v e c o n s i d e r a b l e e f f o r t s o a s i e v e was i n t r o d u c e d which s i m p l y r e f l e c t s a p r e f e r e n c e f o r s i t i n g t h e mine away from go:ulation c e n t r e s . The s a n e s i e v e r e p r e s e n t s t o some e x t e n t t h e d u s t and v i s u a l i n t r n s i o n f a c t 2 r s .

The method of a d d i n g t h e e f f e c t s of t h e f a c t o r s c o u l d be c r i t i c i s e d f o r b e i n g t o o s i m p l e . The r e s u l t s a r e very s e n s i t i v e t o t h e c h o i c e of coding s y s t e n and t h e method does n o t r e c o g n i s e t h a t s o n e f a c t o r s a r e n o r e i a p o r t s n t t h a n o t h e r s . Zle t e c h n i q u e could be modified t o c o v e r s o a e of t h e s e c r i t i c i s m s b u t o n l y z t t h e expense o f making i t more c o n 2 l i c a t e d . Bouever, a s argued

i n t h e p r e v i o u s p a r a g r a p h , t o o much s o p h i s t i c a t i o n a t such an e z r l y s t a g e o f p l a n n i n g c o u l d be w a s t e f u l .

S i n c e t h e r e i s no a b s o l u t e l y c o r r e c t answer t o t h e 2roblern of choosing a n i n e s i t e , . n Q t e c h n i q u e however complicnted c m f i n d i t . N e v e r t h e l e s s , t h e problem h a s t o be s o l v e d znd t h i s is u s u a l l y done by d e b a t e . The s i e v e t e c h n i q u e c a n c e r t a i n l y he12 d i r e c t and i n f o r n t h a t d e b a t e by p r o v i d i n g a framework, which i d e n t i f i e s t h e s i g n i f i c a n t f a c t o r s , and a s e t of bait i n f o r m a t i o n .

C o n c l u s i o n s

Develo?ers a r e f i n d i n g t h a t e n v i r o m e n t d f a c t o r s m u s t be t a k e n i n t o a c c o u n t

i n an i n c r e a s i n g p - o g o r t i o n of t h e d e c i s i o n s t h a t t h e y d k e . S t u d i e s t o he13 do t h i s w i l l u s u a l l y i n v o l v e i d e n t i f y i n g m d i n sone way measuring t h e relev21:t

I

f a c t o r s and t h e n performing an a s s e s s n e n t of t h e i r e f f e c t on t h e d e c i s i o n t o be made. Each s t u d y must be c a r e f u l l y t c i l o r e d t o t h e p r o b l e n .

I n t h i s p a 2 e r we have h i g h l i g h t e d soge of t h e d i f f i c u l t i e s i n c a r r y i n g c::t s u c h s t u d i e s and r e f e r r e d t o two t e c h n i q u e s which have been used t o overcone them. There is one fundamental d i f f i c u l t y t h a t can n e v e r be overcome ho~:;cvzr, and t h a t i s t h e h i g h l y s u b j e c t i v e and emotive n a t u r e of e n v i r o n n e n t a l i s s u e s .

The a u t h o r b e l i e v e s t h a t OR must s t o p s h o r t of t r y i n g t o 2roduce ' I c o r r e c t m w e r s T 1 a r d be s a t i s f i e d ?with p r o v i d i n g b e t t e r d a t a m d a frarrework 13r s t r u c t u r i n g t h e d e b e t e .

Xnvironmental inpact matrix for a new deep coal nine

Prospect

Sieves

Nore suitable Areas f o r c l o s e r examination

Im Dokument Planning for Planning - Coal: Issues for the Eighties (Seite 129-141)