Intern experience at the Conoco VCM plant: an internship report

I N T E R N E X P E R T E N C E AT T i!E C O N O C O V C M P L A N T

An I n t e r n s h i p R e p o r t by

J A M E S .3 OS I AH HALL III

ubrr.ittad to the C o l l e g e of Engineerir.g

of Tex* s A41>* Ur« {v e r s 1 ty

f u l f i l l i a s n t of t he r e q u i r e m e n t . f o r . t h e

D e c e m b e r 1975

,jor .Su.Di.ec.t:. m d u s i n a !. t;ng/; nee ring

An I n t e r n s h i p R e p o r t by J A M E S J O S I A H HALL III A p p r o v e d as to s t y l e and c o n t e n t by: TChairmarf of C o m m i t t e e ) ( He ad of D e p a r t m e n t ) TmI D e c e m b e r 1975

A B S T R A C T

In tern E x p e r i e n c e at the C o n o c o VCM Plant. ( D e c e m b e r 1975) J am e s J o s i a h Hall III, B.S., Te xas A& M U n i v e r s i t y

M.E., Texas A& M U n i v e r s i t y

C h a i r m a n of A d v i s o r y C o m mi tt ee : Dr. R a lp h J. V e r n o n

This r e p o r t deals w it h the p r o f e s s i o n a l e n g i n e e r i n g e x p e r i e n c e a c c r u e d by the a u t h o r d u r i n g an e i g h t - m o n t h

i n t e r n s h i p w i t h C o n o co C h e m i c a l s in Lake C ha r l e s , L o u i s i a n a . B a c k g r o u n d of the i n t e r n s h i p is d i s c u s s e d , i n c l u d i n g the i n t e r n ' s p o s i t i o n in the o r g a n i z a t i o n of the plant.

M a j o r p r o j e c t s a s s i g n e d d u r i n g the i n t e r n s h i p are d e ­ fined. The p r o b l e m of o c c u p a t i o n a l e x p o s u r e to vinyl c h l o r i d e , a toxic c h e m i c a l , is a d d r e s s e d and a s y s t e m for m o n i t o r i n g e m p l o y e e e x p o s u r e is d e v e l o p e d and pr op o s e d . The e x p o s u r e to i n d u s t r i a l noise at the p l a n t is e v a l u a t e d and r e c o m m e n d a t i o n s are p r e s e n t e d .

A C K N O W L E D G M E N T S

I am i n d e b t e d to Dr. R. J. Ver n on , my c o m m i t t e e c h a i r ­ man, for his ad vi c e , e n c o u r a g e m e n t and a s s i s t a n c e t h r o u g h o u t my g r a d u a t e p r o g r a m . His e n t h u s i a s m p r o v i d e d the c a t a l y s t w i t h o u t w h i c h I w o u l d not have been m o t i v a t e d to p u r s ue g r a d u a t e t r a i n i n g in i nd u s t r i a l h y g i e n e e n g i n e e r i n g .

I am also e s p e c i a l l y i n d e b t e d to Dr. R. B. Ko n z e n for his counsel and g u i d a n c e t h r o u g h d i f f i c u l t p e ri od s.

I m u s t also e x t e n d my a p p r e c i a t i o n to my g r a d u a t e c o m ­ m i t t e e m e m b e r s , Dr. M. J. Fox, Dr. E. M. B a i l e y and

Dr. C. A. P h i l l i p s for t he ir v a l u a b l e c o n t r i b u t i o n s to my e d u c a t i o n a nd d e v e l o p m e n t .

V

DEDICATION

T A B L E OF C O N T E N T S P A G E I N T R O D U C T I O N ... 1 D o c t o r o f E n g i n e e r i n g I n t e r n s h i p ... 1 C o n o c o V C M P l a n t ... . . . 1 P r o c e s s O r i e n t a t i o n ... 4 V i n y l C h l o r i d e O v e r v i e w ... 5 V C M M O N I T O R I N G S Y S T E M ... 9 C u r r e n t M o n i t o r i n g T e c h n i q u e ... 9 A u t o m a t e d C o n c e p t ... .. 11 M e a s u r e m e n t o f S y s t e m P a r a m e t e r s . . . . 12 P r o p o s e d S y s t e m . . ... '14 A c c u r a c y V e r i f i c a t i o n ... 1 7 A c c u r a c y R e q u i r e m e n t s ... 17 R e g r e s s i o n A n a l y s i s ... . . . . 18 E n v i r o n m e n t a l P r o c e d u r e ... 19 E V A L U A T I O N O F N O I S E E X P O S U R E ... 26 B a c k g r o u n d ... 26 S u r v e y a n d R e s u l t s ... ... 2 8 C o n c l u s i o n s ... 35 A d m i n i s t r a t i v e C o n t r o l s ... 37 P e r s o n a l P r o t e c t i o n E q u i p m e n t ... 38 ^ H e a r i n g C o n s e r v a t i o n P r o g r a m ... 39 O T H E R P R O J E C T S ... .. 4 0 C a l i b r a t i o n o f D o s i m e t e r M o n i t o r i n g S y s t e m . . 40 C o n f i d e n c e L e v e l ... 4 0 I n t e r p r e t a t i on o f S t a n d a r d ... 45 C a l i b r a t i o n T e c h n i q u e s ... 46 T u r n a r o u n d L o s s C o n t r o l P r o g r a m ... S U M M A R Y A N D O B S E R V A T I O N S ... 51 R E F E R E N C E S ... ... 52 ' A D D I T I O N A L R E F E R E N C E S ... 53 A P P E N D I X A R E G R E S S I O N A N A L Y S I S C A L C U L A T I O N S . . . . 54 A P P E N D I X B C A L I B R A T I O N OF V C M D O S I M E T E R M O N I T O R I N G S Y S T E M ... 59

v i i

T A B L E OF C O N T E N T S ( c o n t i n u e d )

P A G E A P P E N D I X C C H R O N O L O G Y O F S I G N I F I C A N T E V E N T S

L I S T O F F I G U R E S F I G U R E P A G E 1 O r g a n i z a t i o n a l c h a r t ... 3 2 V C M P l a n t fl o w d i a g r a m ... 6 3 A u t o m a t e d m o n i t o r i n g s y s t e m . . . ... 15 4 T i m e c h a r t ... 20 5 R e g r e s s i o n l i n e ... .. ... 23 6 A v e r a g e s o u n d l e v e l s - - l o w p r o d u c t i o n rates. 30 7 A v e r a g e s o u n d l e v e l s - - f u l l p r o d u c t i o n . . . 31 8 N o i s e d o s i m e t e r data s u m m a r y ... .. 34 9 H i s t o g r a m ... .. . 43 10 Norm al c u r v e ... 43 11 V C M p e r s o n n e l m o n i t o r i n g s y s t e m - - c a l i b r a t i o n s c h e m a t i c ... . . . . 47

1

I N T R O D U C T I O N

D o c t o r of E n g i n e e r i n g I n t e r n s h i p

| This r e p o r t deals wi t h the p r o f e s s i o n a l e n g i n e e r i n g j

! e x p e r i e n c e a c c r u e d by the a u t h o r d ur i n g an e i g h t - m o n t h Doc-

j

J a n u a r y 6, 1975 t h r o u g h A u g u s t 22, 1975.

The i n t e r n s h i p is an integral part of the d e g r e e require' ments for the D o c t o r of E n g i n e e r i n g d egree. The o b j e c t i v e s are t w o - f o l d : (1) to a f f o r d to the e n g i n e e r i n g s t u d e n t the o p p o r t u n i t y to a p p l y his k n o w l e d g e and e d u c a t i o n to the s o l u t i o n of a s p e c i f i c prac ti c al p r o b l e m of i n t e r e s t to an in dustrial f i r m and (2) to p e r m i t the s t u d e n t to p e r f o r m in a n o n - a c a d e m i c e n v i r o n m e n t and to gain an a w a r e n e s s of the o r g a n i z a t i o n a l a p p r o a c h to p r o b l e m s [1]. N e g o t i a t i o n s for an i n t e r n s h i p p o s i t i o n w i t h C o n t i n e n t a l Oil C o m p a n y w e r e i n i t i a t e d as a r e s u l t of the fi n a n c i a l s u p p o r t by C o n o c o to T e x as A&M U n i v e r s i t y t h r o u g h an I nd ustrial H y g i e n e E n g i n e e r i n g F e l l o w s h i p . C o r r e s p o n d e n c e I with Dr. R o b e r t L embke, C o r p o r a t e M edical D i r e c t o r , soon

j

j Lake C h a r l e s . P r i m a r y a s s i g n m e n t was to the VCM P l a n t w h i c h p r o d u c e s vinyl c h l o r i d e mo no m er .

C o n o c o VCM P lant

The C o n o c o VCM P l a n t at W e s t l a k e , L o u i s i a n a , was c o n ­ s t r u c t e d with the la t e s t t e c h n o l o g y in 1968. It was, at that time, one of the l a r g e s t v ol u m e plan t s of its kind in the world. A n nu al p r o d u c t i o n is 30 0, 00 0 m e t r i c tons. A m a jo r p o r t i o n of the vinyl c h l o r i d e m o n o m e r (VCM) p r o d u c e d

in Lake C h a r l e s is s h i p p e d to C o n o co p o ly vi n yl c h l o r i d e (PVC) f a c i l i t i e s in O k l a h o m a and M i s s i s s i p p i . C o n o c o also ships this i m p o r t a n t b asic m at e r i a l to f i f t e e n c o u n t r i e s and is c u r r e n t l y the l a r g e s t U.S. e x p o r t e r of VCM.

Vinyl c h l o r i d e is a c l e a r c o l o r l e s s gas w h ic h, upon p o l y m e r i z a t i o n , forms p o l yv in y l c h l o r i d e resin, a basic raw material for a b o u t 55 p e r c e n t of the p l a s t i c p ro d u c t s

c u r r e n t l y in use.

VCM has r e c e n t l y been la be l e d as a c a r c i n o g e n by the federal g o v e r n m e n t . C o n s e q u e n t l y , s t r i n g e n t c o n t r o l s have been p l a c e d upon its use and m a n u f a c t u r e . A l l o w a b l e e x ­ p osures to e m p l o y e e s have been r e d u c e d 99.8 pe rc e n t , f r o m 500 parts per m i l l i o n to one part per m i l l i o n as an e i g h t - hour d ai ly a v e r a g e . T r e m e n d o u s sums of e n g i n e e r i n g time and capital h a ve be e n i n v e s t e d in the p la nt to r e d u c e w o r k e r s e x p o s u r e to VCM gas to m e e t the new c o m p l i a n c e limit.

At the VCM P l a n t the c o m p l i a n c e e f f o r t is j o i n t l y m a i n ­ tained a m o n g the p r o c e s s e n g i n e e r i n g d e p a r t m e n t , the s a f e t y d e p a r t m e n t , and the l a b o r a t o r y . F i g u r e 1 shows the o r g a n i ­ zation of the plant. D i r e c t s u p e r v i s i o n for the i n t e r n s h i p

3

was a s s i g n e d to Mr. C. Earl G r e m i l l i o n , C . S. P . , the p lant Safety D i r e c t o r . To s u p p l e m e n t Mr. G r e m i l l i o n ' s s u p e r v i s i o n of the i n t e r n s h i p , an a d v i s o r y c o m m i t t e e was f o r m e d c o n s i s t ­ ing of Mr. G. D. J o h n s o n , P.E., E n v i r o n m e n t a l E n g i n e e r for the Chemical C o m p l e x , and Dr. J. E. Ce arley, D i r e c t o r of E nv i r o n m e n t a l C o n t r o l . This c o m m i t t e e held r e g u l a r m e e t i n g s to advi se and g u id e the intern.

Process O r i e n t a t i o n

Vinyl c h l o r i d e m o n o m e r is s y n t h e s i z e d f r o m f e e d s t o c k s of e t h y l e n e and e l e m e n t a l c h l o r i n e via d i r e c t c h l o r i n a t i o n and o x y c h l o r i n a t i o n and s u b s e q u e n t thermal " c r a c k i n g . "

The p r o c e s s is i n i t i a t e d by the d i r e c t c h l o r i n a t i o n of e t h y l e n e w i t h c h l o r i n e to f or m e t h y l e n e d i c h l o r i d e (EDC), a chemical i n t e r m e d i a t e . H H H H - ■ \ / ' i C = C + Cl ? ---- > H - C - C - H (1) ' s i I H H Cl Cl EDC, in c r u d e form, u n d e r g o e s p u r i f i c a t i o n by f r a c t i o n ­ ation. Pure EDC is then t h e r m a l l y "c r a c k e d " in p rocess f ur naces to f o r m VCM, h y d r o g e n c h l o r i d e (HC1) and u n c r a c k e d EDC. H H Cl H i 1 A ' ' H - C - C - H — C = C + HC1 (2) i i ✓ x Cl Cl H H

5

The h y d r o g e n c h l o r i d e b y - p r o d u c t is r e c y c l e d to the o x y c h l o r i n a t i o n stage. Here it is r e a c t ed with o x y g e n from c o m p r e s s e d a i r and m o r e e t h y l e n e to form more c r ud e EDC.

H H H H

s ' i i

2 C = C + 4HC1 + 0 2 --- > 2H - C - C - H + 2 H 20 (3)

✓ V I I

H H Cl Cl

Fig u re 2 is a s i m p l i f i e d s c h e m a t i c of the p r o c e s s flow.

Vinyl C h l o r i d e O v e r v i e w

"Vinyl c h l o r i d e a p p e a r s to be a m a t e r i a l of r e l a t i v e l y low t o x i c i t y . The p r i n c i p a l [ p h y s i o l o g i c a l ] r e s p o n s e seems to be one of c e n t r a l n e r v o u s s y s t e m d e p r e s s i o n , w h i c h may result in s y m p t o m s of d i z z i n e s s and d i s o r i e n t a t i o n . . ."[2] This s t a t e m e n t is e x e m p l a r y of the co ns e n s u s on the t o x i c i t y of vinyl c h l o r i d e p r i o r to J a n u a r y 1974. It was c o n s i d e r e d h az a rd ou s p r i m a r i l y as a f l a m m a b l e gas and t h e r e f o r e c ap a b l e , at high c o n c e n t r a t i o n s , of fire a n d / o r e x p l o s i o n s . * R e ­

cently, a d e f i n i t e r e l a t i o n s h i p b e t w e e n c h r o n i c VCM e x p o s u r e s and a n g i o s a r c o m a , a rare and fatal l iver cancer, has been d e m o n s t r a t e d . W o r l d w i d e , s l i g h t l y o ve r 30 d e a th s to a n g i o ­ s arcoma have been a t t r i b u t e d to o c c u p a t i o n a l e x p o s u r e to VCM.

As a r es u l t , the U.S. D e p a r t m e n t of Labor, O c c u p a t i o n a l

*The f l a m m a b l e r a nge for VCM is 3.6 p e r c e n t to 26.4 p e r ­ cent w h i c h c o r r e s p o n d s to 3 6 ,0 0 0 ppm and 2 6 4 , 0 0 0 ppm, r e s p e c ­ tively.

F i g u r e 2. VC M P l a n t fl ow d i a g r a m .

7

Safety and H e a l t h A d m i n i s t r a t i o n (OSHA) has o r d e r e d a sharp r ed uc ti o n in w o r k e r s ' e x p o s u r e to vinyl c h lo ri de . The new standard, e f f e c t i v e April 1, 1975, re qu i re s that VCM levels in the air that w o r k e r s b r e a t h e be held to one part vinyl c hl oride per m i l l i o n parts of air by volume, a v e r a g e d over an e i g h t - h o u r shift. Actual levels may e x c e e d one pa r t per m il l i o n (ppm) for s h o r t period s, but they m u s t a v e r a g e out

to no mo re than five ppm for any f i f te en m i n u t e p e r i o d within the e i g h t - h o u r time span [3].

The s t a n d a r d r e q u i r e s that the one ppm level be a t t a i n e d by " e n g i n e e r i n g and w o r k p r a c t i c e c o n t r o l s " w h e n e v e r such controls are " f e a s i b l e . " R e s p i r a t o r y p r o t e c t i o n can be used as a control m e a s u r e only wh en all o t h e r m e a s u r e s fail to reduce VCM c o n c e n t r a t i o n s to w i t h i n the p e r m i s s i b l e limits.

E x p l i c i t r e q u i r e m e n t s are also o u t l i n e d for person n el m o n i t o r i n g , m e d i c a l s u r v e i l l a n c e , r ec o r d k ee pi ng , r e s p i r a ­ tory p r o t e c t i o n and r e g u l a t e d areas. To m e e t the perso nn e l m o n i t o r i n g r e q u i r e m e n t s , the e m p l o y e r m u s t m e a s u r e the

e x p o s u r e of e a c h e m p l o y e e . Such m o n i t o r i n g m u s t be r e p e a t e d at least m o n t h l y fo r any e m p l o y e e e x p o s e d in exc es s of

one ppm. It m u s t be r e p e a t e d q u a r t e r l y for any e m p l o y e e exp o se d in e x c e s s of one half of one ppm. W h i l e no p a r t i c ­ ular m o n i t o r i n g t e c h n i q u e is s p e c i f i e d , m i n i m u m a c c u r a c y r e q u i r e m e n t s are o u t l i n e d in the s ta n d a r d . The c o m p a n y (employer) m u s t be p r e p a r e d to d e m o n s t r a t e that its p e r ­ sonnel m o n i t o r i n g s y s t e m meets t hese a c c u r a c y criter ia .

In the ar ea of me di c al s u r v e i l l a n c e , a p r o g r a m must be i nst it ut ed for e ac h e m p l o y e e e x p o s e d to VCM e x p o s e d in

excess of the " a c t i o n level" (0.5 ppm). The p r o g r a m must include, at a m i n i m u m : (1) a general physical e x a m i n a t i o n with s p e c i f i c a t t e n t i o n to d y s f u n c t i o n or a b n o r m a l i t i e s of the liver, k i d n e y s or s p l e e n, (2) a medical hi s to ry , and (3) a b l oo d p r o f i l e . T h e s e r e q u i r e m e n t s mu st be re pe a t e d s e m i a n n u a l l y for e m p l o y e e s in VCM s e r v i c e for ten y ears or more and a n n u a l l y for all o t h e r e m p l o y e e s . The s t a n d a r d requires that t hese and all o t h e r rec or ds a s s o c i a t e d with VCM e x p o s u r e be m a i n t a i n e d for a p e r i o d of not less than thirty y e a rs .

Any ar ea of the p l a n t in w h i c h a m b i e n t VCM c o n c e n t r a ­ tions are c o n s i s t e n t l y in e x c es s of the p e r m i s s i b l e limit (1 ppm) m u s t be d e s i g n a t e d by a p p r o p r i a t e signs as r e g u l a t e d areas. A c c e s s to t h e se areas m u s t be l i m i te d to a u t h o r i z e d personnel. A d a i l y log m u s t be m a i n t a i n e d of the name and social s e c u r i t y n u m b e r of all p e rs o n s e n t e r i n g a r e g u l a t e d a r e a .

9

VCM M O N I T O R I N G S Y S TE M

The p r i m a r y a s s i g n m e n t for the i n t e r n s h i p was to i n ­ v estigate a l t e r n a t i v e a p p r o a c h e s to personnel m o n i t o r i n g of VCM e x p o s u r e a nd d e t e r m i n e t h eir f e a s i b i l i t y , both technical and e c on o mi c. The f i r s t step was to b e co me f a m i l i a r w it h the e x i s t i n g p e r s o n n e l m o n i t o r i n g t e c h n i q u e and learn its a d va n ta ge s and d i s a d v a n t a g e s .

C u r r e n t M o n i t o r i n g T e c h n i q u e

The e x i s t i n g s y s t e m of person ne l m o n i t o r i n g for o r g a n i c vapor ( i n c l u d i n g VCM) i n v o l v e s the use of d o s i m e t e r s . The d os i m e t e r is a small p o r t a b l e d e vi ce w hi c h , w h e n c a r r i e d on the p e r s o n of an e m p l o y e e , i n t e g r a t e s his a v e r a g e e x p o s u r e to VCM t h r o u g h o u t the w o r k - d a y . The devi ce c o n si s ts , b r i e f ­ ly, of a small b a t t e r y - p o w e r e d air pump w h i c h draws a

m ea s u r e d v o l u m e of air f r o m the b r e a t h i n g zone of an e m p l o y ­ ee, t h r o u g h a tube f i l l e d wi th a c t i v a t e d c h ar co a l. Any o rganic v a p o r p r e s e n t will be a d s o r b e d on the c ha r c o a l . The a m o u n t of VCM a d s o r b e d is m e a s u r e d (by gas c h r o m a t o g ­ raphy) so that the a v e r a g e a t m o s p h e r i c c o n c e n t r a t i o n at the b r e a t h i n g zone can be c a l c u l a t e d [5].

This t e c h n i q u e r e p r e s e n t s a c c e p t e d p r a c t i c e in i n d u s ­ trial h y g i e n e and is e n t i r e l y a d e q u a t e in c l as si ca l m o n i t o r ­ ing a p p l i c a t i o n s . For e x a m p l e , the e v a l u a t i o n of an o c c u ­ pational e x p o s u r e to a toxic s u b s t a n c e g e n e r a l l y c o ns i s t s

of the f o l l o w i n g s e q u e n c e .

An a d e q u a t e n u m b e r of samp le s are t aken and a n a l y z e d , ideally r e p r e s e n t i n g a " t yp ic al " w or k e x p e r i e n c e . The sampling r e s u l t s g iv e an i n d i c a t i o n as to w h e t h e r a p o t e n ­ tially h a z a r d o u s e x p o s u r e exists. If the e x p o s u r e is e x ­ cessive, steps are t a ke n to e s t a b l i s h appropri ate c o n t r o l s . Repeat e d m o n i t o r i n g e s t a b l i s h e s the e f f e c t i v e n e s s of the controls. W h e n e x p o s u r e s have been r e d uc e d to "safe" l e v ­ els, c o n t i n u e d p e r s o n n e l m o n i t o r i n g is g e n e r a l l y u n n e c e s ­ sary.

For this type of m o n i t o r i n g , the use of d o s i m e t e r s is ideal. The s a m p l e is dr awn d i r e c t l y f r o m the b r e a t h i n g zone of the w o r k e r e l i m i n a t i n g many of the so ur ce s of e r ro r in e s t i m a t i n g his e x p o s u r e .

H o w e v e r , the s y s t e m does have its d i s a d v a n t a g e s . It is c u m b e r s o m e for the e m p l o y e e who m u s t w e a r the d o s im et e r. It re qu i re s a s i g n i f i c a n t a m o u n t of l a b o r a t o r y a n a l y s i s time and it n e c e s s i t a t e s s c h e d u l i n g and t r a i n i n g of e m p l o y ­ ees in the p r o p e r care of the d o s i m e t e r s . C o m p l i a n c e with the new O S H A s t a n d a r d s r e q u i r e s the a c q u i s i t i o n of t r e m e n ­ dous a m o u n t s of data. P er s o n n e l m o n i t o r i n g b e c o me s a c o n ­ tinuing p r o g r a m r a t h e r than a m a t t e r of takin g and a n a l y z ­ ing i n f r e q u e n t s a m p l e s . C o m p l i a n c e w it h OS H A s t a n d a r d s using d o s i m e t e r m o n i t o r i n g m e t h o d o l o g y can impose a very s i g n i f i c a n t w o r k l o a d in l a b o r a t o r y a n a l y s i s time and re c o r d keeping m a n - h o u r s .

A u t o m a t e d C o n c e p t A s y s t e m for m o n i t o r i n g pers on ne l e x p o s u r e s to VCM in c o m p li an ce w i t h the O S H A s t a n d a r d s s h ou ld m e e t the f o l l o w ­ ing criter ia : 1. E f f e c t i v e l y m e a s u r e perso nn el e x p o s u r e s to VCM, m e e t i n g the r e q u i r e m e n t s of the OS HA S t a n d a r d fo r E x p o s u r e to Vinyl C h l o r i d e (29CFR 1 9 1 0 . 93q). 2. I m p o s e a m i n i m u m w o r k l o a d on l a b o r a t o r y and a d m i n i s t r a t i v e p e r s o n n e l . 3. P o s s e s s a l a r m c a p a b i l i t i e s w h i c h c o uld a l e r t e m p l o y e e s in the e v e n t that VCM c o n c e n t r a t i o n s e x c e e d a p r e s e t value.

4. Be c a p a b l e of a s s i s t i n g in the control of access to r e g u l a t e d areas and c o m p i l i n g re co r ds of

a u t h o r i z e d p er s o n n e l w h o have e n t e r e d the areas. 5. Be t e c h n o l o g i c a l and e c o n o m i c a l l y f e as ib l e.

The s e a r c h for an i m p r o v e d t e c h n i q u e for m e e t i n g these criteria for VCM m o n i t o r i n g had, as its u l t i m a t e goal, the e l i m i n a t i o n or at l e as t r e d u c t i o n of the manual p r o c e s s i n g time. Such a s e a r c h n a t u r a l l y g r a v i t a t e s t o w a r d m e t h o d s of a u t o m a t i n g the m o n i t o r i n g " sy st e m. " A m o n i t o r i n g s y s t e m to m e a s u r e t i m e - w e i g h t e d a v e r a g e (TWA) e x p o s u r e to VCM m us t have the c a p a b i l i t y to m e a s u r e and c o r r e l a t e th ree b asic input v a r i a b l e s : (1) a m b i e n t VCM c o n c e n t r a t i o n s in vari ou s plant areas, (2) e m p l o y e e l o c a t i o n s , and (3) d u r a t i o n of e x p o s u r e .

M e a s u r e m e n t of S y s t e m P a r a m e t e r s

The f i r s t p a r a m e t e r , a m b i e n t VCM c o n c e n t r a t i o n s , is c ur r e n t l y b e i n g m o n i t o r e d by two pr oc es s gas c h r o m a t o g r a p h s located in the p l a n t control room. Each of th ese c h r o m a t ­ ographs s e q u e n t i a l l y m o n i t o r s ten f i x e d - p o i n t l o c a t i o n s in the plant. T h e r e f o r e , a m b i e n t VCM c o n c e n t r a t i o n s at t w e nt y f i x e d - p o i n t l o c a t i o n s are m o n i t o r e d t h r o u g h o u t the day.

Each point is m e a s u r e d at a p p r o x i m a t e l y t e n - m i n u t e i n t e r ­ vals. O u t p u t f r o m the c h r o m a t o g r a p h s is r e c o r d e d on s trip charts in the c ontrol room and m a i n t a i n e d on file.

The two r e m a i n i n g p a r a m e t e r s , e m p l o y e e lo c a t i o n and time of e x p o s u r e can be m e a s u r e d by any one of several t e c h ­ niques .

M o t i o n and T i m e S t u d y . One class i ca l m e t h o d for p r e ­ dicting e m p l o y e e l o c a t i o n s in vo l v e s the use of m o t i o n and time study a n a l y s i s . This t e c h n i q u e c o uld p r o d u c e a chart for each job c l a s s i f i c a t i o n o u t l i n i n g lo ca t i o n versus time for a typical w o r k shift. A c o n t i n u i n g wo rk s a m p l i n g plan could be e m p l o y e d to e n s u r e that the actual w o r k s c he me for each job c l a s s i f i c a t i o n did not vary s i g n i f i c a n t l y f r o m the initial s e q u e n c e . This m e t h o d co uld have a p p l i c a t i o n in plants w e r e job tasks are r e p e t i t i v e and t h e r e f o r e p r e d i c t ­ able w i t h a s i g n i f i c a n t level of a c cu ra c y. Ho we v e r , in con ti nu ou s c h e m i c a l p r o c e s s o p e r a t i o n , the job tasks of ope r at io ns and p a r t i c u l a r l y of m a i n t e n a n c e p e r so n ne l are so variable that a m o t i o n / t i m e study a n a l y s i s c o u l d not

13

reliably p r e d i c t l o c a t i o n versus time charts for all e m ­ ployees .

Transmi t t e r . An i n n o v a t i v e a p p r o a c h to m o n i t o r i n g employee l o c a t i o n e m p l o y s the use of m i n i a t u r e e l e c t r o n i c t ra n s m i t t e r s , c a r r i e d by each e m p l o y e e so that his e x a c t position c ou l d be c o n t i n u o u s l y m o n i t o r e d and recorded. While such a t e c h n i q u e w o u l d o b v i o u s l y y i e l d the u l t i m a t e in a cc u r a c y , it w o u l d be c o s t - p r o h i b i t i v e for mo st a p p l i c a ­ tions. In a d d i t i o n , e m p l o y e e r e a c t i o n to a dev ic e w h e r e b y m a n a g e m e n t c o u l d c o n t i n u o u s l y m o n i t o r th eir w h e r e a b o u t s would u n d o u b t e d l y be s t r o n g l y negative.

B a d g e R e a d e r s . A t h i r d a p p r o a c h to m o n i t o r i n g e m p l o y e e locations u t i l i z e s a n e t w o r k of badge readers l o c a t e d at s tr a te gi c p o i n t s in the plant. This not only a p p e a r e d to be the m o s t c o s t - e f f e c t i v e t e c h n i q u e , but also o v e r c o m e s the basic o b j e c t i o n s to time and m o t i o n and t r a n s m i t t e r t e c h ­ niques. By l o c a t i n g b ad ge re ad er s at the e n t r a n c e s to critical a r ea s of the p l a n t (e.g., r e g u l a t e d areas) the time d u r i n g w h i c h any e m p l o y e e m i g h t remain in an area w i t h p o t e n t i a l l y high a m b i e n t VCM levels c ould be logged. Each e mp lo ye e w o u l d c a r r y a un iq u e i d e n t i f i c a t i o n card ( e x i s t ­ ing ID cards c o u l d be used w h e n a p p r o p r i a t e l y p u nc h e d ) and would be r e q u i r e d to "punch in" and "punch out" upon e n t e r ­ ing and e x i t i n g r e g u l a t e d areas.

Data C o m p i l a t i o n and R e d u c t i o n . Data fr o m two of the sources o u t l i n e d a b o v e (i.e., gas c h r o m a t o g r a p h s and ba dge

readers) are r e q u i r e d to c a l c u l a t e e x p o s u r e s (TWA) of p e r ­ sonnel. First, the a m b i e n t VCM c o n c e n t r a t i o n s as a f u n c t i o n of time in v a r i o u s p l a n t a r ea s are m e a s u r e d by the gas

c h r o m a t o g r a p h s and r ec o rd ed . Se co nd , personnel lo c at io n data are g e n e r a t e d by the badge rea de r network. The data from both s o u r c e s m u s t be c o m p i l e d , c o r r e l a t e d and r e d u c e d to g e n e r a t e d a i l y TWA e x p o s u r e s for pl ant em ployees. The TWA e x p o s u r e for an i n d i v i d u a l is c a l c u l a t e d using the f o l ­ lowing eq ua t i o n : j ( T i ) ( C 1 ) TWA = ^ - --- (4) I i = 1 1 ) where C.. = c o n c e n t r a t i o n in ppm

T.. = time e x p o s e d at that c o n c e n t r a t i o h in hours

Such v o l u m i n o u s c a l c u l a t i o n s are best a u t o m a t e d to be p r a c t i c a l l y use fu l . It w o u l d seem, t h e r e f o r e , that the most a p p r o p r i a t e s y s t e m for the C o n o c o VCM Plant w o u l d be one w h i ch u t i l i z e d the e x i s t i n g c h r o m a t o g r a p h s , c o u p l e d with a n e t w o r k of s t r a t e g i c a l l y pl ac e d badge re ad e r s and c en tered a r o u n d a m i n i c o m p u t e r to c o m p i l e and r e d u c e the data to useful f o r m (see F ig u r e 3).

Proposed S y s t e m

Several f irms c u r r e n t l y m a r k e t s y s t e m s u t i l i z i n g badge reader n e t w o r k s s i m i l a r to that o u t l i n e d in F i g u r e 3.

15

FIXED POINT LOCATIONS

Pr el i m i n a r y q u o t e s i n d i c a t e that TANO C o r p o r a t i o n of New Orleans o f f e r s the m o s t c o s t - e f f e c t i v e a pp ro ac h. TAN O' s VCM m o n i t o r i n g p a c k a g e emp lo y s a Digital PDP-11 m i n i c o m ­ puter to c o n t i n u o u s l y m o n i t o r the two input va ri a b l e s . Any m ea sured c o n c e n t r a t i o n h i g h e r than a p r es e t limit w ou ld cause an a l a r m s y s t e m to a c ti va t e. Each pers o n e n t e r i n g the plant w o u l d be i s s ue d a u n i qu e badge n um b e r and a w a l l e t - s i z e d card. Upon e n t e r i n g one of the d e s i g n a t e d areas, e m p l o y e e s w o u l d i n s er t their card into the badge reader. A b a c k g r o u n d a m b i e n t c o n c e n t r a t i o n level is used for i n d i v i d u a l s not r e g i s t e r e d into one of the d e s i g n a t e d areas. At the end of each shift, VCM c o n c e n t r a t i o n s c o m ­ piled from c h r o m a t o g r a p h input, c o u p l e d with badge r e a d e r inputs, are i n t e g r a t e d into TWA e x p o s u r e s for each e mp l o y e e . These data are used to p r o d u c e r eports such as:

1. A d a i l y r e p o r t of VCM e x p o s u r e for each p e r s on in the p l a n t du ri n g the p r e c e d i n g t w e n t y - f o u r hours. 2. A l e t t e r i n d i v i d u a l l y a d d r e s s e d to each perso n

e x p o s e d to VCM levels h i g h e r than the p e r m i s s i b l e l im i t (an O S H A r e q u i r e m e n t ) .

S y s t e m c o m p o n e n t s and p r e l i m i n a r y price quot es are listed below:

PDP-11 C o m p u t e r w / 3 2 K P r o c e s s o r 7 B a d g e Rea d er s

T D A C I n t e r f a c e

1 7 A p p l i c a t i o n S o f t w a r e I n s t a l l a t i o n Dual C a s s e t t e Disk 1A 36 P r i n t e r B o o t s t r a p C a s s e t t e S y s t e m P ri ce $ 5 8 , 0 0 0 A d d i t i o n a l B ad ge Re ad e r s ($1650 ea.) VCM m a i n t e n a n c e p e r s o n n e l w o u l d p r o v i d e m a t e r i a l s (wire, conduit, etc.) and l a b or for i n s t a l l a t i o n of badge re a d e r s and e qu i p m e n t . E x p e r t i s e for s y s t e m "hook up" is i n c l u d e d in q u o te d price.

A c c u r a c y V e r i f i c a t i o n

A cc u ra cy R e q u i r e m e n t s

The a u t o m a t e d m o n i t o r i n g system, as p r o p o s e d by TANO C o r p o r a t i o n a p p e a r s to m e e t the r e q u i r e m e n t s i n i t i a l l y e s ­ t ablished for an a u t o m a t e d m o n i t o r i n g s y s t e m wi t h one p o s ­ sible e x c e p t i o n - - a c c u r a c y . The a c c u r a c y of personnel mo ni t o r i n g via f i x e d p o i n t m o n i t o r s has not been v erified.

P a r a g r a p h 1 9 1 0 . 9 3 q (c) (4) of the 0SHA VCM s t a n d a r d s t a t e s :

The m e t h o d of m o n i t o r i n g and m e a s u r e m e n t shall have an a c c u r a c y (with a c o n f i d e n c e level of 95 percent) of not less than plus or m i nu s 50 p e r c e n t from 0.25 t h r o u g h 0.5 ppm, plus or m inus 35 p e r c e n t from over

0.5 ppm t h r o u g h 1.0 ppm, and plus or m i nus 25 p e r ­ c en t o v e r 1.0 p p m .

If an a u t o m a t e d m o n i t o r i n g s y st em is to be used to d em o n s t r a t e c o m p l i a n c e w i t h the OSHA r e g u l a t i o n s , then some technique is n e e d e d to v e r i f y the a c c u r a c y of the system.

One w a y to g a g e the res ul ts o b t a i n e d f ro m an a u t o m a t e d m on i t o r i n g s y s t e m is to c o m p a r e the s y s t e m o u t p u t to the results o b t a i n e d by the r e c o g n i z e d m o n i t o r i n g t e c h n i q u e

(personnel d o s i m e t e r s ) . If the data d e r i v e d from m o n i t o r ­ ing an i n d i v i d u a l via an a u t o m a t e d s y s t e m are indeed valid, they s h o u l d c o m p a r e very c l o s e l y wi th the results from

m o n i t o r i n g that sa m e i n d i v i d u a l with a perso nn el dos im et er .

R e gr e ss io n A n a l y s i s

R e g r e s s i o n is a m a t h e m a t i c a l t e c h n i q u e used to m e a s u r e and q u a n t i f y the r e l a t i o n s h i p b e t w e e n two or m or e va ri a b l e s . In this a p p l i c a t i o n t h er e are two v a r i a b l e s ; y, the v alue obtained f r o m m o n i t o r i n g an indi vi d ua l with a d o s i m e t e r and x, the v a l u e o b t a i n e d by m o n i t o r i n g that same individual via the a u t o m a t e d s ystem. Ideally, the two values w o u l d be exactly the same if a l arge n u m b e r of s amples w e r e taken, the r e l a t i o n s h i p b e t w e e n x and y w o u l d be e x p r e s s e d as

x = y (5)

in which ca se the r e g r e s s i o n line w o u l d be a s t r a i g h t line, starting f r o m the o r i g i n and e x t e n d i n g at an a n g l e of

19

45 degrees.

In a c t u a l i t y , due to the a c c u m u l a t i o n of e rr o r from many so urces, the r e l a t i o n s h i p will be s o m e t h i n g o t h e r than a simple x = y. H o w e v e r , if a c o n s i s t e n t r e l a t i o n s h i p

exists, its p a r a m e t e r s can be d e t e r m i n e d th r ou gh a r e g r e s ­ sion a n a l y s i s and a " c a l i b r a t i o n curve" for the a u t o m a t e d system can be de ri v e d .

Experimental P r o c e d u r e

Data C o l l e c t i o n . D u r i n g the m o nt h of June 1975, each employee who was s c h e d u l e d to be m o n i t o r e d via personnel dosimeter was also i s s u e d a time chart (see Fig ur e 4) and requested to m a i n t a i n a r e c o r d of his l o c a t i o n and time expended at t ha t l o c a t i o n d u r i ng that s hi ft w it h p a r t i c u l a r interest to the p l a n t r e g u l a t e d areas. The o b j e c t i v e of this time c h a r t was to o b t a i n the same data that w o u l d be collected by the b a d g e r e a d e r n et w or k, if it we r e i n s t a l l e d and o p e r a t i o n a l . T h a t is, the time charts w o u l d p r o v i d e information as to w he n and how long the e m p l o y e e was in the critical a reas of the plant.

7:00 / 7:15 ✓ 7:30 ✓ 7:45 / 8:00 ✓ 8:15 / 8: 30 ✓ 8:45 ✓ 9:00 / 9:15 / 9: 30 ✓ 9:45 / 10:00 / 10:15 / 10:30 / 10:45 / 11:00 / 11:45 / 12:00 12:15 / 12:30 ✓ 12:45 1:00 / 1:15 / 1 :30 1 :45 / 2:00 / 2:15 2:30 / 2:45 / 3:00 / 3:15 3:30 / / ✓ ✓ / / F i g u r e 4. Time c ha rt

21

This w o r k e r l o c a t i o n i n f o r m a t i o n was then used in c o n ­ j u n c t i o n w i t h the strip c hart o u t p u t from the f ixed p oint gas c h r o m a t o g r a p h s to c a l c u l a t e a TWA e x p o s u r e for each e m p l o y e e (us in g e q u a t i o n (4)). The data thus c a l c u l a t e d r e p r e s e n t e d a s i m u l a t i o n of the data that w o u l d be o b t a i n e d from an a u t o m a t e d m o n i t o r i n g s y s t e m and r e p r e s e n t s the x v a r i a b l e in the r e g r e s s i o n . The r esults from the d o s i m e t e r e v a l u a t i o n on ea ch i n d i v i d u a l r e p r e s e n t the y v a r i a b l e in the r e g r e s s i o n a n a l y s i s .

M a t h e m a t i c a l A n a l y s i s . Any li n e a r r e l a t i o n s h i p b e t w e e n two v a r i a b l e s can be e x p r e s s e d in the form:

y = a + bx

In a l i n e a r r e g r e s s i o n , the u nk no w n s in the e q u a t i o n (a and b) can be c o m p u t e d u s in g the m e t h o d of least sq uares. The f o r m u l a e are s h ow n below: n I (x . - x ) (y . - y) i = 1

--- —

(

6

)

S i n c e the r e l a t i o n s h i p is not strict, i.e., there is some v a r i a n c e of the data f r o m the r e g r e s s i o n line, the c o n ­ fid e nc e limi t s for y for an o b s e r v e d v alue of x can be c a l ­ c u l a t ed u si ng the f o l l o w i n g f or mu l ae :

C o n f i d e n c e limits for y:

y = a + bx + t S —

a / 2 ; n - 2 y/x n + n

(x - x ) 2

2

where

ta / 2 .n_2

In this a p p l i c a t i o n a was c a l c u l a t e d to be 0 . 0 98 4 (see A p p e n d i x A) and b was c a l c u l a t e d to be 0.3565. T herefore, the r e g r e s s i o n line or func ti on a l r e l a t i o n s h i p between x and y can be e x p r e s s e d as:

The v a r i a n c e of the data f r om the r e g r e s s i o n line was q u a n ­ tified by c a l c u l a t i n g the u p per and lower 95 p e r c e n t c o n ­ fidence limi ts of y for p a r t i c u l a r values of x. These c on fidence lim it s are s ho wn as P P * in Figu r e 5. Sam pl e c al c ul at io n s a n d data are s h o wn in A p p e n d i x A. The graph shown in F i g u r e 5 is e s s e n t i a l l y a c a l i b r a t i o n curve for the s i m u l a t e d a u t o m a t e d m o n i t o r i n g system. It is used to determine the act ua l e x p o s u r e of an e m p l o y e e who has been m onitored via the a u t o m a t e d system.

S

I ( y i - y ) 2 - b l ( x . - x)(y. - y)

x/y n - 2

23 E Q . CX —1 • (U 00 c •1— _1 r™ =3 00 c LU o O ' ■r-w O (/) UJ a* h - s-« c cn z : CD o c c H-ZD < • Ln Q LU <u I— s-< 2 —1 cn ZD ■i— z : Ll_ t-H U~)

To use the graph, find the x value o b t a i n e d from m o n ­ itoring an i n d i v i d u a l using the a u t o m a t e d system. The "actual" e x p o s u r e of that individual is the c o r r e s p o n d i n g value a l o n g the y - a x i s . For example, if a u t o m a t e d m o n i t o r i n g results i n d i c a t e d that an in dividual was e x p o s e d to 1.5 ppm, Figure 5 w o u l d be used to show that his actual e x p o s u r e

was a p p r o x i m a t e l y 0 . 6 3 ppm. More ov er , the graph i n d ic at es that we are 95 p e r c e n t c o n f i d e n t that his actual e x p o s u r e is be t w e e n 0.60 pp m and 0.67 ppm.

For p u r p o s e s of O S H A c o m p l i a n c e we can be 95 p e r c e n t confident t h a t an e m p l o y e e has not been o v e r e x p o s e d if, in this e x a m p l e , his a u t o m a t e d m o n i t o r i n g r esults are 2.35 ppm or less.

The r e s u l t s of the r e g r e s s i o n an al y s i s show that there is a p r e d i c t a b l e r e l a t i o n s h i p b e t we e n the results o b t a i n e d with d o s i m e t e r m o n i t o r i n g and those o b t a i n e d through a simulated a u t o m a t e d t e c h n i q u e . An a u t o m a t e d system, p r o p ­ erly d e s i g n e d and i n s t a l l e d , c ould be used to d e m o n s t r a t e , with 95 p e r c e n t c o n f i d e n c e , that e m p l o y e e s are not e x p o s e d to VCM in e x c e s s of the p e r m i s s i b l e limit.

In this l i m i t e d study, the r e s u l t i n g a b s o l u t e a c c u r a c y of the s y s t e m did not m e e t the s t r i n g e n t OSHA r e q u i r e m e n t s outlined p r e v i o u s l y . H o w e v e r , several act io n s are a v a i l a b l e which c ou l d r e d u c e the c o n f i d e n c e interval. For example,

the m e t h o d of t r a c i n g e m p l o y e e p o s i t i o n in this e x p e r i m e n t (by means of the t im e chart) was a d m i t t e d l y crude. With a

25

badge r e a d e r n e t w o r k a c t u a l l y i ns t a l l e d , the data o b t a i n e d would be m uc h m o r e precise. C o n s e q u e n t l y , a m or e pre ci se c a l c u l a t i o n of an i n d i v i d u a l TWA e x p o s u r e w o u l d be possible. In a d d i t i o n , a f t e r i n s t a l l a t i o n of the s ystem, the c o m p u t i n g power a f f o r d e d by the PDP-11 m i n i c o m p u t e r w o u l d e n a b l e the o p e r a t o r to s e l e c t the m os t appropri ate i nput data to ma tch d o s i m e t e r r es u l t s .

In s u m m a r y , it is fe l t that an a u t o m a t e d s y s t e m for VCM m o n i t o r , w h e n p r o p e r l y d e s i g n e d and i n s t a l l e d can be used to e f f e c t i v e l y e v a l u a t e personnel e x p o s u r e to VCM

vapors. T h e r e is no r e a s o n why the a u t o m a t e d c o n c e p t c ould not be s u c c e s s f u l l y a p p l i e d to o t h e r e n v i r o n m e n t a l m o n i t o r ­ ing p r o b l e m s .

L as t l y , it was s h ow n ( p r o p r i e t a r y i n f o r m a t i o n ) that the a u t o m a t e d s y s t e m can be e c o n o m i c a l l y j u s t i f i e d by its savings in l a b o r a t o r y and a d m i n i s t r a t i o n ma n - h o u r s .

E V A L U A T I O N OF NOISE E XP O S U R E

B a c k g r o u n d

The o b j e c t i v e of this p r o j e c t was to assess the Cono c o Noise R e d u c t i o n P r o g r a m as i m p l e m e n t e d in the VCM Plant and to ma ke r e c o m m e n d a t i o n s to e n s u r e c o m p l i a n c e w i t h the f o r t h ­ coming OSHA s t a n d a r d on o c c u p a t i o n a l noise ex po s u r e .

O SH A o f f i c i a l s have p r e d i c t e d p r o m u l g a t i o n of a p e r ­ m a n e n t s t a n d a r d s o m e t i m e b e t w ee n m i d - O c t o b e r 1975 and J a n ­ uary 1976. The p r o p o s e d s t a n d a r d re qu ir es that:

1. E m p l o y e e e x p o s u r e to c o n t i n u o u s noise m u st be l i m i t e d to 90 d e ci b e l s A - w e i g h t e d (dBA), time- w e i g h t e d a v e r a g e over an e i g h t - h o u r work day. A new p r o v i s i o n is that an e i g h t - h o u r e x p o s u r e to 85 dBA w o u l d c o n s t i t u t e a daily noise dose of 50 p e r c e n t of the a l l o w a b l e limit.

2. W o r k p l a c e noise levels m u s t be m o n i t o r e d a n n u a l l y to d e t e r m i n e i f any e m p l o y e e is e x p o s e d to 85 dBA or higher, and m o n i t o r i n g must take p lace w i t h i n 30 days of any ch a ng es in w o r k p l a c e e q u i p m e n t or pro ce s s w h i c h m i g h t a f f e c t p l a n t n o i s e levels.

3. E n g i n e e r i n g c o n t r o l s m u s t be d e v e l o p e d and i m ­ p l e m e n t e d w h e r e feasible. Personal p r o t e c t i v e e q u i p m e n t may be used as a control only w he n e n g i n e e r i n g control m e a s u r e s have f a i l e d to

27

r e d u c e n o is e e x p o s u r e to a c c e p t a b l e levels. 4. A p r o g r a m for annual a u d i o m e t r i c t es t i n g for

all e m p l o y e e s e x p o s e d to 50 p e r c e n t of the a l l o w a b l e limit or more.

The n o i s e a b a t e m e n t program, e s t a b l i s h e d several y ea rs ago at the V CM P l a n t had the a v o w e d goal of 92 dBA or less in all p l a n t areas. This level w o u l d p e r m i t m a i n t e n a n c e men to w o r k in any area of the pl ant for as m uc h as six hours p e r w o r k d a y w i t h o u t r e c e i v i n g an e x c e s s i v e dose.

With a f ew i s o l a t e d e x c e p t i o n s , this goal has been reached. It, t h e r e f o r e , a p p e a r s that c o m p l i a n c e w it h the new OS HA noise s t a n d a r d will not pose any u n s u r m o u n t a b l e pr o b l e m s for this plant.

G r i d s u r v e y data i n d i c a t e that the c o n t i n u o u s b a c k ­ g r o u n d s o u n d leve ls in the o p e r a t i n g area ra nge from 85 dBA to 87 dBA. A few areas still e x c e e d the 92 dBA goal set by C o n o c o (and the OSHA e i g h t - h o u r limit of 90 dBA). Th ese areas are not r o u t i n e w o r k s t at i o n s for any e m p l o y e e and, t h e r e f o r e , do not n e c e s s a r i l y c r e a t e daily n oise doses e x c e e d i n g the c o m p l i a n c e limit. Howev e r, some m a i n t e n a n c e tasks r e q u i r e that w o r k e r s rema i n in high noise areas for s u f f i c i e n t time p e r i o d s to r e c e i v e an e x c e s s i v e dose.

Data o b t a i n e d w i t h a u d i o d o s i m e t e r s c o n f i r m e d that there was not a n oise e x p o s u r e p r o b l e m in the p l a n t for r o u t i n e o p e r a t i o n s . F i v e - d a y a v e r a g e s of noise doses for s e l e c t e d job c l a s s i f i c a t i o n s in m a i n t e n a n c e and o p e r a t i o n s

s h o w e d a typical da ily dose of less than 40 p e r c e n t of the a l l o w a b l e limit. H o wever, there are some job tasks in the p l a n t w h i c h do r e s u l t in o v e r e x p o s u r e . R e c o m m e n d a t i o n s for the s o l u t i o n of these s p e c i f i c p ro b l e m s are c o n t a i n e d w i t h i n this report.

S u r v e y and Results

S o u n d l e v el s in the o f f i c e areas, w a r e h o u s e , l a b o r a t o r y and m o s t o u t s i d e w or k areas are c o n s i s t e n t l y b el o w 90 dBA, the O S H A e i g h t - h o u r m a x i m u m for c o n t i n u o u s ex po s u r e . O v e r ­ e x p o s u r e w i t h i n an e i g h t - h o u r w o r k d a y will not o c c u r in these areas.

Gr id S u r v e y . M o s t of the s i g n i f i c a n t n oise sour ce s in the p l a n t w e r e l o c a t e d w i t h i n the b a t t e r y limits, b l oc k I and b l oc k II. The f i r s t step in this study was to m e a s u r e the s o u n d leve l s at t w e n t y - f o o t grid i n t e r v a l s t h r o u g h o u t the o p e r a t i n g area. M e a s u r e m e n t s w er e m ad e w i th a General R ad i o Model 1 5 6 5 - B sound level m e t e r w h i c h meets O SH A r e ­ q u i r e m e n t s . Five r e a d i n g s were taken at each grid l o c a t i o n on n o n - s u c c e s s i v e days at r a nd o m times to a r r i v e at the typical n o i s e level for each point.

The f o l l o w i n g e q u a t i o n is used to c a l c u l a t e a v e r a g e s ound levels:

L 1 L 2 L n

L = 1 0 l o g [ a n t i l o g yj j + a n t i l o g + . . . + a n t i l o g y j j ]

29

w h e r e L. = r a n d o m s o u n d level r e a d i n g s L = a v e r a g e s o u n d level

Two g r i d s u r v e y s w e r e m a de , one at full p r o d u c t i o n r a t e s a nd o n e a t r a t e s o f a p p r o x i m a t e l y 40 p e r c e n t . T h e h i g h e r n o i s e l e v e l s d u r i n g full r a t e s r e f l e c t h i g h e r f l o w r a t e s t h r o u g h v a l v e s , p u m p s , etc. F i g u r e 6 s h o w s the r e s u l t s of the f i r s t g r i d s u r v e y . F i g u r e 7 s h o w s the r e s u l t s o f the g r i d s u r v e y t a k e n at the h i g h e r p r o d u c t i o n r at e s. S o u n d l e v e l s m e a s u r e m e n t s w e r e a l s o m a d e a r o u n d the m o r e i n t e n s e n o i s e s o u r c e s in the p l a n t w h e r e the g r i d s u r v e y d a t a r e v e a l s o u n d l e v e l s w h i c h c o u l d c a u s e p e r s o n n e l e x p o s u r e p r o b l e m s . T h e s e v e n m a j o r h i g h n o i s e a r e a s a n d t h e i r p r i m a r y n o i s e s o u r c e s are l i s t e d b e l o w . S O U N D L E V E L (dBA) 1. BL 301 O x y - A i r C o m p r e s s o r A r e a D e M a g C o m p r e s s o r , i n s i d e e n c l o s u r e A d j a c e n t to e n c l o s u r e Q u e n c h Col. R e f l u x and HC1 F e ed P u m p s ( P 2 0 2 A & B ) 91 92 96 2. BL 5 0 2 R e f r i g e r a t i o n C o m p r e s s o r A r e a I n s i d e e n c l o s u r e 94 S t e a m v a l v e to HC1 r e b o i l e r (FRC 204) 3. C h l o r i n e C o m p r e s s o r B u i l d i n g 9 2 - 9 5 95

F i g u r e 6. A v e r a g e s o u n d l e v e 1 s -1 o w p r o d u c t i o n

31 in oo COin 00 inoo ooID to00 00so r-sCO SO00 SO00 in00 oS

s

S O U N D L E V E L (dBA) 4. W e s t E n d o f B l o c k I S t e a m v a 1ves to 1 i gh t e n d s r e b o i l e r 1nl ( F R C 1 0 9 & 124) 101 H e a v y e n d s r e f l u x p u m p s ( P 1 06 A & B ) 95 L i g h t e n d s r e f l u x p u m p s 94 5. E a s t E n d o f B l o c k I B o i l e r f e e d w a t e r p u m p s (P5 02 A & B ) 92 S t e a m v a l v e to vinyl r e b o i l e r s ( H C V 2 7 2 ) 91 B r e a k d o w n , 150 to 50% s t e a m ( P I C 5 0 6 A ) 91 6. F u r n a c e s (R 2 0 1 , A & B ) B e t w e e n 94 A d j a c e n t 92 7. E a s t E n d o f B l o c k II E t h y l e n e f e e d v a l v e to o x y (FRC 313) 8 8 - 9 8 T h e g e n e r a l n o i s e level in the p r o c e s s a r e a is s u c h that e x c e s s i v e e x p o s u r e c o u l d o c c u r to p e r s o n n e l r e q u i r e d to w o r k in the h i g h n o i s e a r e a s l i s t e d a b o v e f o r e x t e n d e d time p e r i o d s . B e c a u s e a c c u r a t e d a t a as to the a m o u n t of time e m p l o y e e s r e m a i n in h i g h n o i s e a r e a s w e r e n o t a v a i l ­ able, the e x t e n t of the n o i s e e x p o s u r e p r o b l e m in the p l a n t can be m o s t a c c u r a t e l y d e t e r m i n e d o n l y t h r o u g h the use of audi o d o s i m e t e r s .

A u d i o d o s i m e t e r S u r v e y . T h e a u d i o d o s i m e t e r is a p o r t ­ able i n s t r u m e n t w h i c h , w h e n c a r r i e d on the b e l t of an

33 e m p l o y e e f o r an e i g h t - h o u r s h i f t , i n t e g r a t e s his t i me - w e i g h t e d a v e r a g e e x p o s u r e and c o m p u t e s his d a i l y n o i s e d o s e as a p e r c e n t a g e of the a l l o w a b l e limit. F i v e - d a y a v e r a g e s w e r e d e t e r m i n e d f o r s e l e c t e d o p e r a t i o n s a n d m a i n t e n a n c e p e r s o n n e l . O p e r a t i o n s . D u r i n g n o r m a l p l a n t o p e r a t i o n s o u t s i d e o p e r a t o r s f o r b l o c k I a n d b l o c k II m a k e p e r i o d i c s a m p l i n g r o u n d s t h r o u g h the p r o c e s s are a. T h e y t y p i c a l l y s p e n d one to f o u r h o u r s p e r s h i f t in the unit. A u d i o d o s i m e t e r a n a l ­ y s i s o f b o t h j o b s f o r all t h r e e s h i f t s (day, e v e n i n g , a n d night) i n d i c a t e s t h a t the a v e r a g e n o i s e d o s e is a p p r o x i m a t e ­ ly 28 p e r c e n t o f the a l l o w a b l e l i m i t f or the b l o c k I o p e r ­ ator a n d 27 p e r c e n t f o r the b l o c k II o p e r a t o r (see F i g ­

ure 8). T h u s , it a p p e a r s t h a t o p e r a t i o n s p e r s o n n e l a r e n o t o v e r - e x p o s e d to n o i s e d u r i n g n or ma l p l a n t o p e r a t i o n s . H o w ­ ever, m a i n t e n a n c e p r o b l e m s , p r o c e s s u p s e t s o r o t h e r a b n o r ­ m a l i t i e s c o u l d o c c a s i o n a l l y r e q u i r e m o r e t i m e in h i g h n o i s e are as w i t h a r e s u l t i n g p o t e n t i a l f o r an e x c e s s i v e n o i s e d o s e .

Mai n t e n a n c e . W h e r e a s the r o u t i n e of the o u t s i d e o p e r ­ ators is c o m p a r a t i v e l y r e p e a t a b l e and p r e d i c t a b l e , e s t i m a ­ tion o f a " t y p i c a l " d a i l y n o i s e d o s e f or m a i n t e n a n c e e m ­ p l o y e e s p r e s e n t s a s u b s t a n t i a l p r o b l e m . On a n y s p e c i f i c day, m a i n t e n a n c e w o r k m i g h t r e q u i r e t h a t an e m p l o y e e r e m a i n in h i g h n o i s e l e v e l s f o r e x t e n d e d t i m e p e r i o d s . T h a t s a m e e m p l o y e e m i g h t r e c e i v e l i t t l e or no e x p o s u r e to h i g h n o i s e

O P E R A T I O N S B l o c k I O p e r a t o r s N i g h t (5 o b s e r v a t i o n s ) D ay (5 o b s e r v a t i o n s ) E v e n i n g (4 o b s e r v a t i o n s ) N o i s e E x p o s u r e of A 1 1o w a b l e Limi t I---1______ i I

0

50

Too

35

l e v e l s on the f o l l o w i n g day. The a u d i o d o s i m e t e r d a t a f o r m a i n t e n a n c e p e r s o n n e l r e f l e c t this v a r i a b i l i t y . T h e r e a p p e a r s to be no s i g n i f i c a n t d i f f e r e n c e b e t w e e n c r a f t s , i . e . , no o n e c r a f t w a s s i g n i f i c a n t l y m o r e e x p o s e d t h a n the o t h e r s . O v e r a l l , the d a i l y n o i s e d o s e f o r m a i n t e n a n c e wa s 37 p e r c e n t . A l t h o u g h s o m e w h a t h i g h e r than o p e r a t i o n s , t hi s d o s a g e d o e s n o t r e p r e s e n t a c o m p l i a n c e v i o l a t i o n . O n e j o b t as k , c o m p r e s s o r v i b r a t i o n r e a d i n g , di d r e s u l t in an e x c e s s i v e e x p o s u r e (140 p e r c e n t ) . C o n c l u s i ons T h e e x i s t i n g n o i s e e n v i r o n m e n t a n d e m p l o y e e w o r k p r a c ­ t i c e s do n o t r e s u l t in o v e r e x p o s u r e to n o i s e on a r o u t i n e b a s i s as d e f i n e d by the p r o p o s e d O S H A s t a n d a r d . H o w e v e r , t h e r e a r e j o b s w h i c h p e r i o d i c a l l y r e q u i r e e m p l o y e e s to r e m a i n in h i g h n o i s e a r e a s f o r s u f f i c i e n t p e r i o d s to c o n ­ s t i t u t e an e x c e s s in e x p o s u r e . T h e s e e x p o s u r e s , w h i l e n o n - t y p i c a l , a r e n o n e t h e l e s s h a z a r d o u s an d s h o u l d be c o n t r o l l e d . V a r i o u s a v e n u e s a r e a v a i l a b l e to e n s u r e c o m p l i a n c e . R e c o m m e n d a t i o n s to A c h i e v e C o m p l i a n c e G e n e r a l . T h e r e ar e t h r e e r e c o g n i z e d t e c h n i q u e s o f c o n t r o l l i n g n o i s e e x p o s u r e . In t h e i r n o r m a l o r d e r of p r e f ­ e r e n c e , t h e s e are: 1. E n g i n e e r i n g c o n t r o l s - - r e d e s i g n , r e p l a c e m e n t , or e n c l o s u r e o f h i g h n o i s e s o u r c e s .

2. A d m i n i s t r a t i v e c o n t r o l s - - r e a r r a n g e w o r k s c h e d u l e s so t h a t e m p l o y e e s are not r e q u i r e d to r e m a i n in h i g h n o i s e a r e a s for s u f f i c i e n t t i m e to r e c e i v e an e x c e s s i v e dose. 3. P e r s o n a l p r o t e c t i o n e q u i p m e n t - - i s s u e a n d e n f o r c e t he u se o f h e a r i n g p r o t e c t i o n ( p l u g s o r m u f f s ) in h i g h n o i s e ar e a s . T h e p r o p o s e d s t a n d a r d r e q u i r e s t h a t all " f e a s i b l e " e n ­ g i n e e r i n g a n d a d m i n i s t r a t i v e c o n t r o l s be i m p l e m e n t e d to b r i n g n o i s e e x p o s u r e s to w i t h i n p e r m i s s i b l e l i m i t s . P e r ­ sonal p r o t e c t i v e d e v i c e s are d e e m e d a p p r o p r i a t e f o r use o n l y if e n g i n e e r i n g a n d a d m i n i s t r a t i o n c o n t r o l s fail to a d e q u a t e ­ ly r e d u c e n o i s e e x p o s u r e . E n g i n e e r i n g C o n t r o l s W e s t E n d o f B l o c k I . " W h i s p e r T r i m " v a l v e s fo r the r e b o i l e r s on t h e l i g h t e n d s c o l u m n h a v e b e e n o r d e r e d and r e c e i v e d . I n s t a l l a t i o n of t h e s e a c o u s t i c a l l y d e s i g n e d v a l v e s s h o u l d s i g n i f i c a n t l y r e d u c e the n o i s e l e v e l s in this a r e a . D e m a g C o m p r e s s o r ( B L 3 0 1 ) . P l a c i n g s o u n d a b s o r b e n t m a t e r i a l o n t h e w a l l s of this c o m p r e s s o r b u i l d i n g s h o u l d r e d u c e n o i s e l e v e l s i n s i d e f r o m 9 4 - 9 6 d B A to 9 0 - 9 2 d B A by r e d u c i n g r e v e r b e r a t i o n of so u n d . A d d i t i o n a l r e d u c t i o n c o u l d be o b t a i n e d by l a g g i n g the d i s c h a r g e li n e w i t h a h i g h t e m ­ p e r a t u r e v i b r a t i o n d a m p i n g c o m p o u n d . T h e s e c o n t r o l m e a s u r e s

37

s h o u l d r e d u c e the n o i s e level to the 92 d BA goal o r i g i n a l l y e s t a b l i s h e d f o r the p l a n t . [ Note: T h e s e a re the C o n o c o - e s t a b l i s h e d g o a l s . ]

P r o p y l e n e C o m p r e s s o r ( B L 5 0 2 ) . S o u n d a b s o r b e n t m a t e r i a l on the b u i l d i n g w a l l s s h o u l d r e d u c e the s o u n d l e v e l s to

w i t h i n the 92 d B A goal in this a r e a also.

O t h e r s . O t h e r e q u i p m e n t in the p l a n t o c c a s i o n a l l y g e n e r a t e s e x c e s s i v e n o i s e l e v e l s . For e x a m p l e , the s o u n d p o w e r l ev e l o f a p u m p or v a l v e is d e p e n d e n t u p o n the f l o w r a t e t h r o u g h it. T h e r e f o r e , the n o i s e level in the v i c i n i t y of t h a t p i e c e of e q u i p m e n t w o u l d v a r y w i t h p l a n t p r o d u c t i o n r a t e s . It is n o t f e a s i b l e to r e p l a c e or r e d e s i g n e a c h p i e c e o f e q u i p m e n t w h i c h o c c a s i o n a l 1y g e n e r a t e s h i g h n o i s e l e v e l s . H o w e v e r , e q u i p m e n t w i t h h i g h n o i s e c h a r a c t e r i s t i c s c a n be e l i m i n a t e d by a t t r i t i o n . S o u n d p o w e r level s h o u l d b e a m o n g the p r i m a r y d e s i g n c r i t e r i a f o r any new o r r e p l a c e m e n t

e q u i p m e n t c o n s i d e r e d f o r p u r c h a s e by the p l a n t . T h e m a x i ­ m u m a c c e p t a b l e s o u n d p o w e r level s h o u l d be i n c l u d e d in the d e s i g n s p e c i f i c a t i o n s . A d m i n i s t r a t i v e C o n t r o l s T h e t h r e e p r i m a r y h i g h n o i s e l e v e l s in the p l a n t (BL501, B L 3 0 1 , an d c h l o r i n e c o m p r e s s o r b u i l d i n g ) h a v e b e e n d e s i g ­ n a t e d as h i g h n o i s e level a r e a s . A c c e s s to t h e s e a r e a s is c o n t r o l l e d a n d l i m i t e d to a u t h o r i z e d p e r s o n n e l .

P e r s o n a l P r o t e c t i o n E q u i p m e n t T h e d a t a i n d i c a t e t h a t e x c e s s i v e n o i s e d o s e s in this p l a n t a r e l i m i t e d to n o n - t y p i c a l a n d / o r i n f r e q u e n t j o b t a s k s w h i c h r e q u i r e a b n o r m a l e x p o s u r e t i me s in the h i g h n o i s e a r e a s . P a r a g r a p h 1 9 1 0 . 9 5 (c) (3) o f the O S H A S t a n d a r d s t a t e s : H e a r i n g p r o t e c t o r s m a y be p r o v i d e d to, a n d u s e d by an e m p l o y e e to l i m i t n o i s e e x p o s u r e s in lieu of f e a s i b l e e n g i n e e r i n g and a d m i n i s t r a t i v e c o n t r o l s if the e m p l o y e e ' s e x p o s u r e o c c u r s no m o r e t h a n o n e d ay p e r w e e k . T h e r e f o r e , it a p p e a r s t h a t c o m p l i a n c e can be a t t a i n e d by e n f o r c i n g t he u se o f p e r s o n a l h e a r i n g p r o t e c t i o n f o r j o b s in w h i c h h i g h n o i s e l e v e l s a re e n c o u n t e r e d . S p e c i f i c a l l y , h e a r i n g p r o t e c t i o n s h o u l d be m a n d a t o r y f o r e n t r y i n t o the f o l l o w i n g a r e a s : 1. C h l o r i n e c o m p r e s s o r b u i l d i n g 2. B L 5 0 1 b u i l d i n g 3. B L 3 0 1 b u i l d i n g 4. B L 3 0 2 b u i l d i n g (when r u n n i n g ) 5. B e t w e e n R201 A& B In a d d i t i o n , h e a r i n g p r o t e c t i o n s h o u l d be r e q u i r e d a n d its u se e n f o r c e d f o r t he f o l l o w i n g jobs: 1. T a k i n g c o m p r e s s o r v i b r a t i o n r e a d i n g s 2. U s i n g n e e d l e s c a l e r s 3. U s i n g the b a n d saw 4. U s i n g the g r i n d e r

39 5. S a n d b l a s t i n g 6. A n y t i m e w h e n the j o b n e c e s s i t a t e s r e m a i n i n g in h i g h n o i s e l e v e l s for e x t e n d e d p e r i o d s of t i m e H e a r i n g C o n s e r v a t i o n P r o g r a m P a r a g r a p h 1 9 1 0 . 9 5 (g) o f the p r o p o s e d n o i s e s t a n d a r d s p e c i f i e s t h a t all p e r s o n s w h o r e c e i v e a d a i l y n o i s e d o s e equ al to or e x c e e d i n g 0.5 (50 p e r c e n t o f the a l l o w a b l e l im i t) m u s t be c o v e r e d by a h e a r i n g c o n s e r v a t i o n p r o g r a m . At a m i n i m u m , s u c h a p r o g r a m w o u l d i n c l u d e the f o l l o w i n g : 1. A b a s e l i n e a u d i o g r a m f or e a c h e m p l o y e e w h o r e ­ c e i v e s a d a i l y d os e in e x c e s s o f 0.5. 2. S u b s e q u e n t a n n u a l a u d i o m e t r i c t e s t i n g . 3. E a r p r o t e c t o r s f or all e m p l o y e e s w h o s h o w a s i g n i f i c a n t t h r e s h o l d s hift. In t he V C M P l a n t , m o s t o f the m a i n t e n a n c e a n d o p e r a t i o n p e r s o n e l i n f r e q u e n t l y r e c e i v e a n o i s e d o se in e x c e s s of 0.5. T h e r e f o r e , a f o r m a l h e a r i n g c o n s e r v a t i o n p r o g r a m s h o u l d be m a i n t a i n e d f o r t h e s e e m p l o y e e s . For c o m p l i a n c e w i t h t h e p r o p o s e d r e g u l a t i o n , it w o u l d not be n e c e s s a r y to i n c l u d e o f f i c e a n d w a r e h o u s e p e r s o n n e l in the h e a r i n g c o n ­ s e r v a t i o n p r o g r a m .

O T H E R P R O J E C T S C a l i b r a t i o n o f D o s i m e t e r M o n i t o r i n g S y s t e m T h e n e w O S H A S t a n d a r d f o r e x p o s u r e to vinyl c h l o r i d e is e x p l i c i t in its d e l i n e a t i o n of the r e q u i r e m e n t f o r a c c u ­ r a c y in t he p e r s o n n e l m o n i t o r i n g t e c h n i q u e (see p. 17). H o w e v e r , t h e r e w a s c o n s i d e r a b l e m i s u n d e r s t a n d i n g in i n t e r ­ p r e t i n g the s t a t e m e n t . Th e q u e s t i o n a r o s e c o n c e r n i n g w h e t h e r the a c c u r a c y r e q u i r e m e n t s r e f e r to the q u a n t i t a t i v e c h e m i s ­ t ry t e c h n i q u e , to the s a m p l i n g s t r a t e g y , to the s a m p l i n g m e c h a n i s m , or to all t h r e e ; i .e . , t he total m o n i t o r i n g s y s t e m . T h e r e a l s o w a s a p p a r e n t l y s o m e q u e s t i o n as to the m e a n i n g o f the "95 p e r c e n t c o n f i d e n c e l e v e l . " To e l u c i d a t e t he c o n c e p t o f s t a t i s t i c a l c o n f i d e n c e l e v e l s f o r the V C M P l a n t s t a f f , t he f o l l o w i n g p r e s e n t a t i o n w a s d e v e l o p e d . C o n f i d e n c e L e v e l T h e 95 p e r c e n t c o n f i d e n c e level r e q u i r e m e n t e s s e n t i a l l y r e c o g n i z e s t h e f a c t t h a t n o m e a s u r i n g s y s t e m is p e r f e c t l y a c c u r a t e a n d is an a t t e m p t to q u a n t i f y h o w i n a c c u r a t e the t e c h n i q u e m a y be. It is a s t a t i s t i c a l c o n c e p t t h a t is p e r ­ haps b e s t e x p l a i n e d u s i n g an e x a m p l e . A s s u m e t h a t t h e k n o w n c o n c e n t r a t i o n o f v inyl c h l o r i d e v a p o r in a p a r t i c u l a r a r e a is e x a c t l y 5 p a r t s p e r m i l l i o n ( ppm). A s s u m e f u r t h e r t h a t a l a r g e n u m b e r o f s a m p l e m e a ­ s u r e m e n t s , s a y 8 0 0 , a r e t a k e n . O b v i o u s l y , du e to the

41 i n h e r e n t i n a c c u r a c y o f an y m e a s u r i n g s y s t e m , the v a l u e s o b ­ t a i n e d f r o m th e 80 0 o b s e r v a t i o n s will n o t all e q u a l e x a c t l y 5 ppm. H o p e f u l l y , the v a s t m a j o r i t y o f the r e s u l t s w il l be v e r y c l o s e to 5 p p m b u t we w o u l d e x p e c t a f e w to fall f a r t h e r a w a y . S u p p o s e t h a t the 800 s a m p l e o b s e r v a t i o n s c o u l d be s u m m a r i z e d as s h o w n in T a b l e 1. F R E Q U E N C Y 0 13 52 97 156 175 144 102 48 12 1 0 T A B L E 1 C L A S S I N T E R V A L _____ Lp m )_______ 0 . 5 0 . 5 - 1 . 5 1 . 5 - 2 . 5 2 . 5 - 3 . 5 3 . 5 - 4 . 5 4 . 5 - 5 . 5 5 . 5 - 6 . 5 6 . 5 - 7 . 5 7 . 5 - 8 . 5 8 . 5 - 9 . 5 9 . 5 - 1 0 . 5 1 0 . 5

In T a b l e 1 the " F r e q u e n c y " c o l u m n r e p r e s e n t s the n u m ­ b e r o f s a m p l e m e a s u r e m e n t s w h i c h fell w i t h i n the c o r r e s p o n d ­ i ng C l a s s I n t e r v a l R a n g e . T h e s e d a t a can be d i s p l a y e d g r a p h i c a l l y by c o n s t r u c t i n g a h i s t o g r a m (see F i g u r e 9). If the n u m b e r of o b s e r v a t i o n s is i n c r e a s e d i n f i n i t e l y and the s i g n o r r a n g e of the c l a s s i n t e r v a l is d e c r e