REPORT FHWA/NY,SA-86 85

Use of Scrap Automobile Tire Rubber In Highway Construction WILLIAM P. CHAMBERLJN

PRASANTA K. GUPTA

SPECIAL REPORT 85 ENGINEERING RESEARCH AND DEVELOPMENT BUREAU,

Mario M. Cuomo, Governor / Franklin E. White. Commissionor

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_ - - . _ _ t - . - -- - - - . - - - -- - ---- -- -.' - NEW YORK STATE DEPARTMENT OF TRANSPORTATION - -

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USE OF SCRAP WTCIMOBILE TI= RUBBER I N HIGHWAY CONSTRUCTION

W i l l i a m P . C h a m b e r l i n , C i v i l E n g i n e e r I11 P r a s a n t a K . G u p t a , Civi l E n g i n e e r IT

S p e c i a l R e p o r t 85 Hay 1986

ENGINEERING RESURCH AND DEVELOP?IENT BUREAU New York S t a t e Depar tment of T r a n s p o r t a t i o n

S ta te Campus, Albany, New York 12232

CONTENTS

1, INTRODUCTION . . . . . . 1

. . . . . . . . . . . . . . . . . . . . . . . . . . A. O b j e c t i v e s 1 . . . . . . . . . . . . . . . . . . . . . . . . . B . C o n c l u s i o n s I I

C. Recommendations . . . . . . . . . . . . . . . . . . . . . . . 2

11. BACKGROUND . . t . . . . . . 4

A. The Used T i r e P rob lem . . . . . . . . . . . . . . . . . . . . 5 B. Assembly B i l l Number 7020-A . . . . . . . . . . . . . . . . . 5 C. Tsrminology . . . . . . . . . . . . . . . . . . . . . . . . . 5

- ITL. F I N D I N G S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i

A. Pe r fo rmance of Rubber-Modified Hater ia ls . . . . . . . . . . . 7 B . C o s t s . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 C. S c r a p T i r e Use P o t e n t i a l . . . . . . . . . . . . . . . . . . . Y D . The EPA Proposed G u i d e l i n e . . . . . . . . . . . . . . . . . . 13

I I j E. O t h e r P o t e n t i a l Uses . . . . . . . . . . . . . . . . . . . . . F. O t h e r C o n c e r n s . . . . . . . . . . . . . . . . . . . . . . . . l o

REFERENCES 0 . . . . 12

I. INTRODUCTION

A. O b j e c t i v e s

I n r e s p o n s e t o d b i l l which would have r e q u i r e d t h e D e p a r t n e n t of Transporc3- t i o n (DOT) t o u n d e r t a k e a p i l o t pr3gram t o e v a l u a t e t h e u s e f u l n e s s of rubser - mod i f i ed a s p n a l t i n t h e c o n s t r u c t i o n and improvement of highways (L), Goverxo: Cuomo i s s u e d Veto ? lessage No. 78 ( 2 ) . I n t h i s message , t h e DOT was d i r s c t ? a t o :

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1. Survey e x i s t i n g r e s e a r c h on t h e u s e of s c r a p r u b b e r i n t h e c o n s t r u c t i o n * and improvement of h i i h w a y s ,

2 . Recommend a d d i t i o n a l r e s e a r c h o r any o t h e r Ac t ions t h a t nay Se a p p r o p r i 3 t S t o conduc t i n N e w York S t a t e , and

3 . Estimate t h e economic impact of u s i n g s c r a p r u b b e r i n highway pav ing ma- t e r i a l s i n New York.

In r e s p o n s e t o t h i s d i r e c t i v e , DOT r ev iewed e x i s t i n g l i t e r a t u r e on p e r f a r n - a n c e and c o s t of rubbe r -mod i f i ed a s p h a l t s y s t e m s , r ev iewed i t s own e x p e r i e n c e as w e l l as t h a t of t h e NYS Thruway A u t h o r i t y w i t h t h e s e mater ia ls , c o n s u l t s d w i t h r e s e a r c h s t a f f of t h e F e d e r a l Highway A d m i n i s t r a t i o n (FHWA) i n Washing- t o n , DC and some of t h e p r i n c i p a l i n v e s t i g a t o r s i n t h i s f i e l d , e s t i m a t e d t h e economic impact on pav ing c o s t s i n N e w York of u s i n g r u b b e r i n a s p h a l t con- c re te , and s u r v e y e d i t s own f i e l d s t a f f f o r e x p e r i e n c e and s u g g e s t i o n s .

B. C o n c l u s i o n s

1. DOT h a s a p o l i c y of u s i n g waste materials i n c o n s t r u c t i o n when they c a n be shown t o be t e c h n i c a l l y s u p e r i o r a n d / o r c o s t e f f e c t i v e .

2 . Waste rubber is c u r r e n t l y allowed by DOT s p e c i f i c a t i o n s t o be i n c l u d e d i n l i q u i d j o i n t and c r a c k s e a l i n g materials f o r pavements , i n conformance w i t h n a t i o n a l c o n s e n s u s s t a n d a r d s of t h e American S o c i e t y f o r T e s t i n g and Materia 1s.

3 . E x p e r i m e n t a l d a t a on t h e pe r fo rmance and d u r a b i l i t y of rubbe r -moa i r i ed a s p h a l t s in o t h e r highway uses is i n c o n c l u s i v e a t t h i s time. .-

4 . V a r i o u s economic a n a l y s e s i n d i c a t e t h a t t h e s e r v i c e l i f e of i n s t a l l a t i o n s i n v h i c h rubbe r -mod i f i ed pav ing materials a re used would have t o be ex- t e n d e d by 1-1/2 t o 3 times i n 3rder t o r e c o v e r t h e a d d i t i o n a l f i r s t c o s t of t h e s e mater ia l s .

5. The t rchnolas; . r tiid: nay be t n e ! . = . ~ s : e:i.?ensive ,~:d t h a t ,,K:?r.; 71:;;-

3un po ten t i . 11 f o r JasE? t i r e c o n s u x p t i o n i s r u b b e r - f i l l e d a s p n a l c :on- Crete . Based an t h e 1985 q u a n t i c i e s o f a s p h a l t c o n c r e t e u s e d by DOT d 3 2 t h e i r p r i c e s , i t is e s t i m a t e d t h a t a d d i n g two p e r c e n t r u b b e r t 3 aspna;: c o n c r e t e would u s e t h e e q u i v a l e n t o f n i n e m i l l i o n p a s s e n g e r t i r e s per y e a r a t a n e s t i m a t e d t o t a l i n c r e a s e d c o s t of a b o u t $lUO m i l l i o n ( a 60 p e r c e n t i n c r e a s e o v e r c u r r e n t p r i c e s ) , o r a b o u t $11 p e r t i re .

6. The p r o p r i e t a r y p r o d u c t "Plus-Ride" , which i n c o r p o r a t e s a c o a r s e r s i z e d r u b b e r , a p p e a r s t o have some a d v a n t a g e i n i n c r e a s i n g t i r e f r i c t i o n on i c e pavements . However, i t has been a s s o c i a t e d w i t h r a v e l l i n g and p o t n o l i n g i n e x p e r i m e n t a l pavements i n Alaska and can be e x p e c t e d t o i n c r e a s e c 3 s t s by a t l eas t 50 p e r c e n t above c o n v e n t i o n a l materials.

7 . To a c h i e v e c o n s i s t e n t and p r e d i c t a b l e pe r fo rmance , t e c h n i c a l s t a n d a r d s and q u a l i t y a s s u r a n c e p r o c e d u r e s must be deve loped p r i o r t o per-s i : t ing ) r r e q u i r i n g u s e of waste r u b b e r i n pav ing materials.

. 8. The e n v i r o n m e n t a l e f f e c t s of fumes from h i g h t e m p e r a t u r e mixing and t h e F r e s e n c e of c a r b o n b l a c k o r o t h e r c a r c i n o g e n s i n t h e r u b b e r , n u s t a i s < , Se e v a l u a t e d b e f o r e a l l o w i n g ; r i d e s p r e a d u s e .

9 . h procuremen t g u i d e l i n e p roposed by t h e U.S . Envi ronmen ta l P r o t e c t i o n Agency would r e q u i r e c o n s i d e r a t i o n of rubber -modi f ied a s p h a l t f o r a l l highway p r o j e c t s . T h i s p r o p o s a l h a s been o b j e c t e d t o by FHIjA as be ing p r e m a t u r e and u n s u p p o r t e d by p o s i t i v e r e s u l t s i n e x p e r i m e n t a l pavements .

10. No highway pavement u s e s of w a s t e t i r e r u b b e r were i d e n t i f i e d t h a t have n e a r l y t h e p o t m t i a l f o r u s i n g s c r a p t i r e s as do rubbe r -mod i f i ed a s p h a l z s .

C. Recommendations

1. Because e x p e r i m e n t a l u s e s t o d a t e indicate t h a t t h e s i g n i f i c a n t added c o s t o f u s i n g s c r a p r u b b e r i n a s p h a l t - r u b b e r s u r f a c e treatments o r i n t e r l a y e r s , a s p h a l t - r u b b e r concrete or f r i c t i o n c o u r s e s , o r r u b b e r - f i l l e d f r i c t i o n c o u r s e s i s not j u s t i f i e d by a showing of improved pavement pe r fo rmance , n o f u r t h e r c o n s i d e r a t i o n s h o u l d be g i v e n t o s u c h u s e s .

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2 . No new experimental i n s t a l l a t i o n s of rubbe r -mod i f i ed a s p h a l t ( e x c e p t as n o t e d below) s h o u l d be u n d e r t a k e n i n New York S t a t e a t t h i s time. How- e v e r , 33 e x p e r i m e n t a l p r o j e c t s i n C o n n e c t i c u t t h a t have used r u b b e r - f i l l e d a s p h a l t concrete s h o u l d be c r i t i c a l l y e v a l u a t e d and t h e i r pe r fo rmance m o n i t o r e d c l o s e l y . I f t h e r e s u l t s of t h e s e f i e l d e x p e r i m e n t s a re p o s i - t i v e , c o n s i d e r a t i o n s h o u l d be g i v e n t o t e s t i n g a p p l i c a t i o n s i n New York.

3 . C o n s i d e r a t i o n s h o u l d be g i v e n t o t h e d e s i r a b i l i t y o f u s i n g t h e p r a p r i e t a r y

s p e c i f i c s i t e s of h i d h w i n t e r a c c i d e n t f r e q u e n c y where i t s premium c o s t might be j u s t i f i e d . I n t n r s r e g a r d , i t s h o u l d be c o n s i d e r e d o n l y m d e r c a r e f u l l y d e v e l o p e d c r i t e r L 3 .

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5 . Pend ing rece ip t of e x p e r i m e n t a l e v i d e n c e t h a t t h e i n c r e a s e d c o s t s of rub- be r -mod i f i ed p a v i n g m a t s r i a l s a re o f f s e t by e x t e n d e d l i f e a n d / o r r educed m a i n t e n a n c e , o r t h a t t h e added c o s t s c a n be r e d u c e d s i g n i f i c a n t l y , DOT should c o n t i n u e t o res i s t r e q u i r e m e n t s t o p r o c u r e r u b b e r - m o d i f i e d a s p h a l t p a v i n g inaterials.

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11. BACKGKOUND

A . The Used T i r e P r o b l e n

Each y e a r a p p r o x i m a t e l y 2 U O m i l l i o n used a u t o m o b i l e and 40 m i l l i o n usec C ~ J C L t i r e s a r s d i s p o s e d of i n t h e Uni ted S t a t e s ( 3 ) . Vehicle!; r e g i s t e r e d i n Sew York S t a t e a l o n e c o n t r i b u t e a p p r o x i m a t e l y 12-mil l ion t o t h i s t o t a l ( 4 ) . - While some of :hese scrap t i r e s a re used f o r r e s o u r c e and e n e r g y r e c o v e r y ( p e r h a p s 2 5 p e r c e n t ) , t h e v a s t m a j o r i t y a r e l a n d f i l l e d , s t o c k p i l e d i n t i r i d i s p o s a l y a r d s , o r d i s c a r d e d o r d e s t r o y e d i n e n v i r o n m e n t a l l y u n a c c e p t a b l e ways.

A s a s o l i d waste , used t i r e s pose p a r t i c u l a r l y v e x i n g problems. Because Lard- f i l l e d t i r e s a r e n o t b i o d e g r a d a b l e and because whole t i r e s work t o t h e s u r z a c s a s t h e f i l l s e t t l e s , many o p e r a t o r s e i t h e r c h a r g e a d i s p o s a l f e e t o o f f s e t a d d i t i o n a l h a n d l i n g c o s t s o r r e f u s e t o a c c e p t them. Most w i l l n o t a c c e p t t r u c k l o a d q u a n t i t i e s . In a d d i t i o n , c u r r e n t p o l i c y i n many s t a t e s i s t o min- i m i z e t h e u s e of l a n d d i s p o s a l f o r s o l i d aastes .

T h i s s i t u a t i o n h a s l e d t o t h e s t o c k p i l i n g of used t i r e s . However, few m a r k e t s f o r scrap r u b b e r have d e v e l o p e d and t h e r e are e n v i r o n m e n t a l and h e a l t h prob- lems r e l a t e d t o s t o c k p i l i n g . In a d d i t i o n t o be ing u n s i g h t l y , s t o c k p i l e d t i r e s a c c u m u l a t e r a i n water where m o s q u i t o e s b r e e d and t h e y are a f i r e n a z a r d w i t n uncommonly n o x i o u s consequences . T h e r e are c u r r e n t l y f o u r ma jo r t i r e s t o c k - p i les i n New York S t a t e w i t h a t o t a l a c c u m u l a t i o n i n excess of 9 m i l l i o n t i r e s ( 5 ) , p l u s many lesser ones . - The s e a r c h f o r s o l u t i o n s to t h e used t i r e d i s p o s a l p rob lem i s o n e of a number o f t o p i c a l i s s u e s b e i n g a d d r e s s e d by t h e Commission o n S o l i d Waste Management formed by t h e New York S t a t e L e g i s l a t u r e . One of t h e a l t e r n a t i v e s b e i n g con- s i d e r e d by t h e Commission i s t h a t o f i n c l u d i n g p u l v e r i z e d t i r e r u b b e r a s a c o n s t i t u e n t o f a s p h a l t pav ing m a t e r i a l s u sed i n DOT c o n s t r u c t i o n .

B. Assemblv B i l l Number 7020-A

In J u l y 1985, t h e Commission d r a f t e d and t h e S t a t e L e g i s l a t u r e pas sed Assembly B i l l Number 7020-A, An A c t t o Amend t h e Highway L a w , i n R e l a t i o n t o t h e U t i l i z a - t i o n of S c r a p Rubber i n t h e C o n s t r u c t i o n and Improvement of Highways ( 1 ) . - The

- - b i l l , p a s s e d i n J u l y 1985 and s u b s e q u e n t l y v e t o e d by t h e Governor ( L ) , would have r e q u i r e d t h e NYSDOT t o i n i t i a t e a p i l o t p r o j e c t i n 1986 t o e v a i u a t r t h e u s e of scrap r u b b e r as a n a d d i t i v e i n a s p h a l t pav ing materials. F u r t h e r , t h e b i l l would have r e q u i r e d t h a t t h e Commiss ioner of T r a n s p o r t a t i o n makd s p e c i f i c recommendat ions t o t h e Governor b e f o r e A p r i l 1987 w i t h r e g a r d t o f a c i l i t a t i n g

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L Y ? ~ b r l 2 i r a b & r ;n n i g h w a y ; 3 I s t r U 2 t l 3 n and i a p r ? v e 3 e ? ~ s . T : i s a l b a i x c l u d e d d p r 3 v i s i o n per3L:tLng t h e Comi'lSSlOner o t T r a n s p o r t a t i o n ~ ( 3

r 2 q u 1 r e that a f i x e d p e r c e n t a g e a € r u b b e r d e r i v e d from s c r a p a u t 3 : i r<b b e r n c o r ? o r a t * d i n a s p h a l : p a v i n g mater ia l s .

While e x p r e s s i n g s u p p o r t f o r t h e b i l l ' s i n t e n t t o f i n d i n g a s o l u t i o n t o t h e v e h i c l e t i r e d i s p o s a l p rob lem, t h e Governor t o o k e x c e p t i o n t o i t s s u b s t a n c e . In h i s v e t o message , he gave t h e f o l l o w i n g d i r e c t i o n t o t h e Commissioner of T r a n s p o r t a t i o n :

" I d i r e c t t h e D e p a r t s e n t of T r a n s p o r t a t i o n t o conduc t i t s own s u r v e y of t h e e x i s t i n g r e s e a r c h i n t h i s a r e a and t o f o r m u l a t e i t s recomnen- d a t i o n s as t o any a d d i t i o n a l r e s e a r c h which c a n be c o n d u c t e d i n Xeu York and any o t h e r a c t i o n s which N e w York can t a k e t o i n c r e a s e t h e u s e of s c r a p r u b b e r i n t h i s way. T h i s a n a l y s i s n u s t a l s o c l e a r l y s e t f o r t h t h e economic i m p a c t on highway r e p a v i n g p r o j e c t s which r e q u i r e - ments f o r t h e u s e of s c r a p r u b b e r i n a s p h a l t p a v i n g would impose."

C . T e r n i n o l o g y

F i g u r e 1 is i n c l u d e d t o p r o v i d e a common t e r m i n o l o g y and u n d e r s t a n d i n g of t h e . v a r i I u s p a v i n g materials t o which waste r u b b e r might be added.

Commonly used terms r e l a t i n g t o r u b b e r - m o d i f i e d s y s t e m s i n c l u d e a s p h a l t - r u b b e r , i n which p a v i n g g r a d e a s p h a l t i s p r e b l e n d e d w i t h r u b b e r , and r u b b e r - f i l l e d t r e a t m e n t s i n which scrap r u b b e r i s added d r y t o t h e a s p h a l t c o n c r e t e mix:,Jre.

In a s p h a l t - r u b b e r systems, 18 t o 26 p e r c e n t of r u b b e r by t o t a l w e i g h t of t h e b l e n d is premixed w i t h l i q u i d a s p h a l t a t a n e l e v a t e d t e m p e r a t u r e t o form a new b i n d e r material. These new b i n d e r s c a n t h e n be u s e d i n t h e same ways as con- v e n t i o n a l l i q u i d a s p h a l t s . Where t h e b i n d e r i s s p r a y e d o n t o t h e s u r f a c e and f o l l o w e d by d i s t r i b u t i o n and r o l l i n g of a c o v e r a g g r e g a t e , t h e material is re- f e r r e d t o as a seal c o a t , c h i p seal or s u r f a c e t r e a t m e n t . When s u c h a t rea t - ment i s p l a c e d between t h e l a y e r s of a pavement s y s t e m to r e t a r d r e f l e c t i o n c r a c k i n g , i t i s r e f e r r e d t o as a n i n t e r l a y e r . By f a r , most of t h e a p p l i c a - t i o n s of r u b b e r - m o d i f i e d s y s t e m s i n t h e U n i t e d S t a t e s t o d a t e are of t h e s e two k i n d s . Because e x p e r i m e n t a l i n s t a l l a t i o n s in New York S t a t e have f a i l e d t o d e m o n s t r a t e a b e n e f i t t o u s i n g i n t e r l a y e r s (6,9), and b e c a u s e s u r f a c e t r ea t - merits are n o t a p p r o p r i a t e f o r t h e h i g h e r t r a f f i c volumes and s p e e d s t h a t t y p i c a l l y o c c u r on t h e S t a t e and I n t e r s t a t e s y s t e m s u n d e r d i r e c t DOT s u p e r -

. v i s i o n , t h e s e t e c h n o l o g i e s o f f e r l i t t l e o p p o r t u n i t y f o r using waste t i r e r u b b e r .

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When a s p h a l t - r u b b e r i s used as a l i q u i d b i n d e r and mixed w i t h f i n e and c o a r s e a g g r e g a t e , i t i s c a l l e d a s p h a l t c o n c r e t e , or a s p h a l t c o n c r e t e f r i c t i o n c o u r s s i f t h e new material i s used o n l y i n t h e s u r f a c e t o e n h a n c e f r i c t i o n . However,

- t h e s e mater ia l s are r a r e l y m a n u f a c t u r e d b e c a u s e i t is c h e a p e r t o p l a c e t h e d r y r u b b e r d i r a c t l y i n t o t h e mix ( r u b b e r - f i l l e d s y s t e m s ) w i t h o u t p r e b l e n d i n g .

R u b b e r - f i l l e d systems, a r e used i n a p p l i c a t i o n s where s p r a y i n g i s n o t r e q u i r - e d , t h a t i s , i n a s p h a l t c o n c r e t e and a s p h a l t c o n c r e t e f r i c t i o n c o u r s e s . While

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& ? h a l t C o n c r e t e 1 A s p h a l t C o n c r e r e I- F r i c z i o n Course

--

c!i<r$ has been ' ~ r l l y l i n i c e d e x p e r i 5 n c e ; l i t 5 zhttse = : i s ~ s . n s , t h e y >if?_r t n r ; r ?a t c?s t a p p o r t u n i t y for use o t .13ste r u b b e r because t n e y r e p r e s e n t :-I* -~d; I F

us? of a s p h a l t i n DoT c o n s t r u c t i o n and b e c a u s e t h e y a r e p r o b a b l y l e s s c s s c ; j t h a n a s p h a l t - r u b b e r systems, which r e q u i r e p r e b l e n d i n g .

"Plus-Ride" is t h e p r o p r i e t a r y name f o r a s p e c i a l t y p e of r u b b e r - f i l l e d s y s t e s i n wh ich r e l a t i v e l y l a r g e p a r t i c l e s (1 /16" -1 /4" ) are i n c o r p o r a t e d i n t h e mix- t u r e as a n a g g r e g a t e r e p l a c e m e n t . T y p i c a l l y , t h e mix c o n t a i n s 3 t o 4 p e r c e n t r u b b e r by w e i g h t of t h e t o t a l mix and r e q u i r e s t h e amount of a s p h a l t used i n t h e mix t o be i n c r e a s e d f rom t h e 4 t o 6 p e r c e n t i n a c o n v e n t i o n a l mix t o 7 t 3 9 p e r c e n t f o r a P lus -R ide m i x t u r e . P lus -R ide vas d e v e l o p e d i n Sweden i n t h e 1960s. I t -.as been r e p o r t e d t3 be n o r e d u r a b l e and s k i d r e s i s t a n t t h a n con- v e n t i o n a l mixes in Sweden. The s y s t e m h a s a l s o been r e p o r t e d t o p r o v i d e some d e g r e e of w i n t e r t i n e i c e c o n t r o l b e c a u s e i t s i n c r e a s e d f l e x i b i l i t y and t h e p r e s e n c e of r u b b e r p a r t i c l e s a t t h e s u r f a c e i s s a i d t o i n t e r f e r e vi:h t h e bond ing of i c e t o t h e p a v e n e n t s u r f a c e ( 1 0 , l l ) . --

111. FINDINGS

A. Pe r fo rmance of Rubber-Modif ied Yater ia l s

By f a r t h e most comprehens ive and r e c e n t c r i t i c a l e v a l u a t i o n of t h e p e r r o r x - a n c e of rubbe r -mod i f i ed a s p h a l t pav ing materials i s t h a t c o n d u c t e d by t h e Texas T r a n s p o r t a t i o n I n s t i t u t e f o r t h e F e d e r a l Highway A d m i n i s t r a t i o n under a n a t i o n a l pooled- funds s t u d y ( 1 2 ) . Under t h a t s t u d y , 210 e x p e r i a e n t a l r u b b e r - m o d i f i e d pavements b u i l t i n the c o n t i g u o u s U n i t e d S t a t e s be tween 1 9 7 7 and 138.; were e v a l u a t e d f o r t h e i r r e l a t i v e pe r fo rmance compared t o c o n t r o l s e c t i o n s b u i l t w i t h c o n v e n t i o n a l non-rubber m a t e r i a l s . q u a n t i f i a b l e measu res were deve loped f o r r a t i n g t h e c o n d i t i o n of t h e r e s u l t i n g pavement based on t h e s s v e r i c y and amount of e i g h t d i f f e r e n t pavement d i s t r e s s t y p e s . E v a l u a t i Q n s were made of each of t h e s i x p r i n c i p a l t y p e s of r u b b e r m o d i f i e d a spna l t pa*Ji?g a a t e r i a l s . The r e s u l t s , i n summary form, a r e p r e s e n t e d i n F i g u r e 2 , showing whe the r t h e pe r fo rmance was worse t h a n , t h e same as , o r b e t t e r t h a n u s e of a c o n v e n t i o n a l a s p h a l t mix.

1 . Asphal t -Rubber S e a l C o a t s The pe r fo rmance of t h i s t r e a t m e n t i n d i c a t e d a n a p p r o x i m a t e l y normal d i s t r i b u t i o n b u t w i t h a n e g a t i v e skew, t h a t i s , a g r e a t e r number of p r o j e c t s per formed worse t h a n c o n v e n t i o n a l a s p h a l t ria- t e r i a l s r a t h e r t h a n b e t t e r . In n e a r l y one-ha l f o f t h e 59 p r o j e c t s , t h e r e was no d i s c e r n i b l e d i f f e r e n c e . While i n s t a n c e s of n e g a t i v e p e r f o r a a n c e were conc luded t o be related l a r g e l y t o d e f i c i e n t c o n s t r u c t i o n practices r a t h e r t h a n t o f u n d a m e n t a l d e f i c i e n c i e s of t h e rubbe r -mod i f i ed materials t h e m s e l v e s , f e w e r t h a n 20 p e r c e n t of t h e e x p e r i m e n t a l a s p h a l t - r u b b e r pave- ments o u t p e r f o r m e d t h e projects which used c o n v e n t i o n a l a s p h a l t materials. Pe r fo rmance is l i k e l y t o improve w i t h e x p e r i e n c e i n u s e of t h e r u b b e r m o d i f i e d seal c o a t material, however.

2. Asphal t -Rubber I n t e r l a y e r s P e r f o r m a n c e of i n t e r l a y e r s l i k e w i s e f o l l o w e d a no rma l d i s t r i b u t i o n w i t h a n e g a t i v e skew and', as w i t h seal c o a t s , a p p r o x i - m a t e l y onc-ha l f of t h e 90 p r o j e c t s per formed s imilar t o p r o j e c t s w i t h con- v e n t i o n a l a s p h a l t materials and a p p r o x i m a t e l y 20 p e r c e n t b e t t s r . I t was a l s o c o n c l u d e d c h a t t h e n e g a t i v e pe r fo rmance of i n t e r l a y e r s was due t o d e f i c i e n t c o n s t r u c t i o n practices u n r e l a t e d t o t h e materials t h e m s e l v e s . Pe r fo rmance is l i k e l y t o improve as e x p e r i e n c e i n u s e of t h e s e materials i n c r e a s e s a l s o .

3, R u b b e r - F i l l e d A s p h a l t C s n c r e t e Approx ima te ly 30 p e r c e n t of t h e 54 pro- _- j ec t s of t h i s t y p e showed i n p r o v e d pe r fo rmance compared t o p r o j e c t s w i t h c o n v e n t i o n a l materials and o n l y t h r e e pe r fo rmed worse . , Host D f t h e p r o j - e c t s i n d i c a t i n g improved pe r fo rmance c o n t a i n e d 1 p e r c e n t r u b b e r by t o t a l w e i g h t of mix. G e n e r a l l y , t h o s e p r o j e c t s w i t h more t h a n 2 p e r c e n t 6f r u b b e r i n d i c a t e d no improvenen t .

b

L

3uo D e r- F i 1 l e d F r i c t i o n Course

'"I

S w S

Asphalt-3ubber Frict ion Caurse Concrete

N = 7 N = I&

,in, 3 3 jn,n .. 3 3 .r( S !J

4 . Asphal t -Xubber F r i c t i ~ n C j u r s e 9n:y 5 p r o j e c t s d e r 2 i 2 c l J c e d L ? t-,= ,: .:- f o r t h i s t r e a t m e n t A n a no g e n e r a l c o n c l u s i o n s arawn. O f tile J pr3;cs:s o b s e r v e d , 2 p e r f o r a e d worse, 1 t h e same, and 2 b e t t s r t h a n p r o j e c t s -'ni:n u sed c o n v e n t i o n a l a a t e r i a l s .

5 . Aspha l t -Rubber C o n c r e t e Few p r o j e c t s i n t h i s t r e a t m e n t c a t e g o r y were found f o r i n c l u s i o n i n t h e s t u d y . Of t h e 7 which were, 3 per fo rmed worse and 4 t h e same as t h e p r o j e c t s which u s e d c o n v e n t i o n a l materials. Because of t h e l i m i t e d number of p r o j e c t s i n t h e s t u d y , no g e n e r a l c o n c l u s i o n s c a n be drawn w i t h r e g a r d t o pe r fo rmance .

6. R u b b e r - F i l l e d F r i c t i o n Course ?'a g e n e r a l c o n c l u s i o n s f o r t h i s t y ? e of t r e a t m e n t u e r e p o s s i b l e b e c a u s e of t h e few a p p l i c a t i o n s o b s e r v e d . iiow- e v e r , of t h o s e o b s e r v e d , more pe r fo rmed s i g n i f i c a n t l y worse t h a n t h e i r c o n t r o l .

I n summary, n a t i o n a l e x p e r i e n c e t o d a t e w i t h rubbe r -mod i f i ed a s p h a l t pav ing materials is i n c o n c l u s i v e . That i s , t h e r e i s no c o n s i s t e n t e v i d e n c e t h a t . t h e s e materials w i l l p r o v i d e improved pe r fo rmance and l o n g e r l i f e o v e r con- v e n t i o n a l materials c u r r e n t l y i n u s e . T h i s c o n c l u s i o n i s c o n s i s t e n t w i t h t h e e x p e r i m e n t a l use of a s p h a l c - r u b b e r i n t e r l a y e r s i n New York S t a t e . Both t h e DOT (2 , l ) and t h e NYS Thruway A u t h o r i t y ( 8 , 9 ) - - have found t h a t w h i l e t h e s e t r e a t m e n t s may d e l a y t h e o n s e t and r e d u c e t h e w i d t h of r e f l e c t i o n c r a c k i n g i n i t i a l l y , a f t e r t h r e e y e a r s t h e r e i s no d e t e c t a b l e e f f e c t . L a b o r a t o r y and f i e l d e x p e r i m e n t s w i t h b o t h l a t ex and crumb r u b b e r c o n d u c t e d by DOT i n 1965 (13) l i k e w i s e f a i l e d t o show d e t e c t a b l e b e n e f i t s from t h e i r i n c o r p o r a t i o n i n a s p h a l t c o n c r e t e p a v i n g mixes . -

The most e n c o u r a g i n g d a t a from t h e N a t i o n a l Poo led Funds S t u d y i s t h a t r e l a t - i n g t o r u b b e r - f i l l e d a s p h a l t c o n c r e t e f o r which a l m o s t 95 p e r c e n t of t h e rub- b e r - n o d i f i e d pavements e i t h e r e q u a l l e d o r e x c e e d e d t h e p e r f o r m a n c e of t h e c o n v e n t i o n a l materials. While many of t h e s e p r o j e c t s were i n c l u d e d i n o n l y s h o r t s e c t i o n s of pavement and few had b e e n o b s e r v e d o v e r a v e r y l o n g p e r i o d , t h e f a c t t h a t 35 of them were b u i l t i n t h e n e i g h b o r i n g s t a t e of C o n n e c t i c u t o f f e r s a n e x c e l l e n t o p p o r t u n i t y t o o b s e r v e t h e i r s u b s e q u e n t pe r fo rmance c l o s e l y .

Those who a d v o c a t e t h e u s e of waste t i r e r u b b e r i n p a v i n g m a t e r i a l s f r e q u e n t l y r e f e r t o t h e p o s i t i v e e x p e r i e n c e c i t e d by t h e C i t y of P h o e n i x , A r i z o n a f o r t h e i r a s p h a l t - r u b b e r c h i p seals ( i . e . , s u r f a c e t r e a t m e n t s , seal c o a t s ) which t h e y s ta te cost 1.5 times t h a t of c o n v e n t i o n a l seals b u t l a s t twice as l o n g (14). While t h e r e is no b a s i s f o r d i s p u t i n g t h i s e x p e r i e n c e , i t i s n o t rep- r e s e n t a t i v e of e x p e r i e n c e n a t i o n w i d e , n o r c a n i t be s a i d t o be i n d i c a t i v e of what c o u l d be e x p e c t e d i n r e g i o n s of s e v e r e climate s u c h as t h e n o r t h e a s t .

B e C o s t s - -- As p a r t of t h e N a t i o n a l Pooled-Funds S t u d y ( 9 ) , c o s t c o m p a r i s o n s were made of t h e rubber-modif i e d t r e a t m e n t s f o r which s u f T i c i e n t i n f o r m a t i o n was t h o u g h t t3 e x i s t . These c o m p a r i s o n s i n c l u d e d o n l y a s p h a l t - r u b b e r seal c o a t s , a spha l t - r u b b e r i n t e r l a y e r s and a s p h a l t - r u b b e r c o n c r e t e . The c o m p a r i s o n s were based on

i i r j t C J ~ ~ S o n l y , s i n c e r e l i a b l e ? r e d i : c i o n s o i s e r . J i c e Li re f J r ch? rdc3=:-

q o d i f i e d s y s t e n s ;rers n o t posSlbLe. ,An i n t e r e s t rate? O K i p e r s e n t ana z e r j a a i n t e n a n c e were assumed f d r t h e a n a l y s e s . The s e r v i c e Life ; r h i c h wouid 3 2 n e c e s s a r y f o r t h e a s p h a l t - r u b b e r t r e a t m e n t s t o have a n a n n u a l c o s t comparsd t o c o n v e n t i o n a l a s p h a l t materials was computed , a s suming t h e l a t t e r had scr- v i c e l i v e s of 3 t o 12 y e a r s .

Based on t h e s e a n a l y s e s , i t was e s t i m a t e d t h a t t h e f o l l o w i n g i n c r e a s e s i n s e r v i c e l i f e would have t o be r e a l i z e d by t h e a s p h a l t - r u b b e r treatments i n o r d e r t o r e c o v e r t h e i r h i g h e r f i r s t c o s t s :

A s p h a l t - r u b b e r seal c o a t 2 t o 3 times A s p h a l t - r u b b e r i n t e r l a y e r 1 .5 t o 2 times A s p h a l t - r u b b e r c o n c r e t e 2 t o 2 . 5 times

These r e s u l t s are c o n s i s t e n t w i t h an i n d e p e n d e n t a n a l y s i s conduc ted by DOT u s i n g p r i c e s t y p i c a l of c o n s t r u c t i o n i n New York S t a t e ( 1 5 ) . F i n d i n g s of t h e N a t i o n a l Pooled-Funds S t u d y s u g g e s t t h a t s u c h enhancemen= of s e r v i c e l i f e a r 2 un 1 i k e l y . Economic a n a l y s e s s i m i l a r t o t h e above were n o t made f o r r u b b e r - f i l l e d s y s t e m as par t of t h e poo led - funds s t u d y . However, i t h a s been s u g g e s t e d t h a t :hey may have lower f i r s t c o s t s t h a n a s p h a l t - r u b b e r systems b e c a u s e p r e b l e n d i n g of t h e r u b b e r and a s p h a l t i s n o t r e q u i r e d .

Apply ing a v e r a g e c o s t i n c r e a s e f a c t o r s o b t a i n e d i n d e p e n d e n t l y f o r 3 3 r u b b e r - f i l l e d a s p h a l t c o n c r e t e p r o j e c t s i n C o n n e c t i c u t t o 1985 w e i g h t e d a v e r a g e Did prices i n New ' fork S t a t e , i t i s e s t i m a t e d t h a t t h e a n n u a l c o s t of i n c o r p o r a t - ing scrap t i r e r u b b e r i n a s p h a l t c o n c r e t e a l o n e would be a p p r o x i m a t e l y SlOO m i l l i o n f o r a 2 p e r c e n t r u b b e r a d d i t i o n , o r t h e e q u i v a l e n t of a p p r o x i m a t e l y $11 p e r t i r e . I t i s n o t e d t h a t t h e u n i t prices used t o estimate t h e s e c o s t s are based upon l i m i t e d and small scale e x p e r i m e n t a l u s e s of scrap r u b b e r , and t h a t t h e economies a s s o c i a t e d w i t h p o s s i b l e w i d e r u s e might have a s i g n i f i - c a n t , though unknown, impac t on t h e s e c o s t estimates. N e v e r t h e l e s s , i t is h i g h l y p r o b a b l e t h a t r u b b e r m o d i f i e d materials would c o n t i n u e t o be more c o s t l y t h a n c o n v e n t i o n a l a s p h a l t materials.

Al though no c o s t f i g u r e s have been p u b l i s h e d f o r t h e e x p e r i m e n t a l pavements i n A l a s k a t h a t i n c o r p o r a t e d P lus -R ide ( l l ) , d a t a f rom t h e N a t i o n a l Pooled-Funds S t u d y s u g g e s t t h a t were Plus-Ride t o b e used i n New York S t a t e i t would add as much as 50 p e r c e n t t o t h e i n - p l a c e c o s t of c o n v e n t i o n a l hot-mixed a s p h a l t c o n c r e t e s u r f a c e c o a r s e materials.

C. S c r a p T i r e Use P o t e n t i a l

I n 1985, t h e DOT used a p p r o x i i n a t e l y 4,000,OOU g a l l o n s of l i q u i d a s p h a l t ( t h e -form t h a t would be u s e d f o r s u r f a c e t r e a t m e n t s and i n t r r l a y e r s ) , and $,bGd,oUO t o n s of a s p h a l t c o n c r e t e i n i t s c o n s t r u c t i o n program. I t i s e s t i m a t e d t h a t t h e s e q u a n t i t i e s would u s e t h e f o l l o w i n g number of scrap p a s s e n g e r t i r e s :

I n s u r f a c e t r e a t m e n t s a t 2 5 p e r c e n t a s p h a l t r e p l a c e m e n t

2 50,000

In J s p h a l t c a n c r e t e a t i j e i rcent r u b b 2 r

I n a s p h a l t z o n c r e t e a t 2 p e r c e n t r u b b e r

D. The EPA Proposed G u i d e l i n e

A s p h a l t c o n t a i n i n g r e c l a i m e d r u b b e r would have t o be c o n s i d e r e d f o r a l l h i g h - way p r o j e c t s a c c o r d i n g t o a p roposed new g u i d e l i n e r e c e n t l y p u b l i s h e d by t h e E n v i r o n m e n t a l P r o t e c t i o n Agency (EPA). The G u i d e l i n e f o r F e d e r a l Procurement of A s p h a l t Xa te r i a l s C o n t a i n i n g Ground T i r e Rubber f o r C o n s t r u c t i o n and Xeha- b i l i t a t i o n of Paved S u r f a c e s , i s s u e d F e b r u a r y 20, 1986 ( 1 5 ) , imp lemen t s pro- v i s i o n s of t h e Resource C o n s e r v a t i o n and Recovery A c t o f 1 9 7 6 r e q u i r i n g reuse of c e r t a i n s o l i d wastes s p e c i f i e d b y EPA.

C i t i n g i t s p o l i c y of u s i n g waste materials when t h e y are t e c h n i c a l l y s u p e r i o r o r c o s t e f f e c t i v e , DOT f i l e d a n o b j e c t i o n t o t h e p roposed g u i d e l i n e based a n t h e f a i l u r e of r u b b e r - m o d i f i e d a s p h a l t p r o d u c t s to meet e i t h e r of t h e s e c r i - . teria. In a d d i t i o n , DOT c i t e d t h e need t o a d d r e s s t h e p o t e n t i a l l y n e g a t i v e e n v i r o n m e n t a l e f f e c t s of fumes from h i g 5 t e m p e r a t u r e mix ing of r u b b e r i n a s - p h a l t p l a n t s , and t h e impact of c a r b o n s l a c k and o t h e r c a r c i n o g e n s c o n t a i n s d i n t i r e s b e f o r e manda t ing t h e u s e of t h i s t e c h n o l o g y ( 1 7 ) .

The FHWA h a s a l s o t a k e n e x c e p t i o n t o t h e p roposed g u i d e l i n e . FHWA h a s p o i n t e d o u t t h a t t h e g u i d e l i n e ' s r e q u i r e m e n t t h a t n a t i o n a l c o n s e n s u s s t a n d a r d s n u s t e x i s t f o r t h e p roposed r u b b e r - m o d i f i e d m a t e r i a l s p r e s e n t l y l i m i t s t h e g u i d e - l i n e ' s a p p l i c a b i l i t y t o j o i n t : sealers. They have a l s o n o t e d t h a t t h e e f f z c - t i v e n e s s of r u b b e r - m o d i f i e d a s p h a l t i n o t h e r u s e s i s i n c o n c l u s i v e . F u r t h e r , FHWA n o t e s t h a t a manda to ry u s e of r e c l a i m e d r u b b e r may be u n e n f o r c e a b l e be- c a u s e of t h e i n a b i l i t y t o d e t e r m i n e t h e d i f f e r e n c e be tween reclaimed and v i r g i n r u b b e r i n a s p h a l t mixes (18) .

-

-

E. O t h e r P o t e n t i a l Uses

A q u e s t i o n n a i r e s u b m i t t e d t o t h e 57 New York S t a t e County Highway S u p e r i n - t e n d e n t s and t h e 11 NYSDOT Materials E n g i n e e r s s o l i c i t e d t h e i r e x p e r i e n c e and ideas on o t h e r a l t e r n a t i v e s f o r u s i n g scrap t i res o r r e c l a i m e d t i r e r u b b e r i n c o n s t r u c t i o n a p p l i c a t i o n s . While a number o f u s e s were s u g g e s t e d , none even a p p r o a c h e s t h e p o t e n t i a l f o r s c r a p t i res t h a t r u b b e r - m o d i f i e d a s p h a l t s do, o t h e r t h a n u s i n g p u l v e r i z e d s c r a p t i r e s as a f i l l material f o r highway and o t h e r u s e s .

F. O t h e r Conce rns

A number of c o n c e r n s o t h e r t h a n t h o s e of p e r f o r m a n c e and c o s t have been ex- . .p ressed w i t h r e g a r d t o t h e immediats w i d e s p r e a d or manda to ry u s e o L r u b b s r -

m o d i f i e d p a v i n g materials. Two a r e of p a r t i c u l a r c o n c e r n t o DOT b e c a u s e t h e y impact d i r e c t l y on manage.oent sr t h e c a p i t a l c o n s t r u c t i o n and s a i n t e n a n c e p rograms . These are q u a l i t y a s s u r a n c e and e n v i r o n m e n t a l effects .

L A

?.egarding t h e f i r s t , ~ j i r f r e is d t ? r e s e n t n o n a r - i J n a l c o n s e w u s s t a n d a r d 323ins: w h i c h che q u a l i t y +lid u n i f o r n i t y of r 2 c l a i m e d r u b b e r can be e v a l u a t e d 5 ~ r t n e uses p r o p o s e d , o r p r o c e d u r e s f o r c o m p l i a n c e s a m p l i n g and t e s t i n g . U n t i l q u a l - i t y and c o n s i s t e n c y s t a n d a r d s a r e d e v e l o p e d and c a n be a d h e r e d t o , t h e r e c a n be no a s s u r a n c e of p r e d i c t a b i l i t y and r e l i a b i l i t y f o r t h e r e s u l t i n g a s p h a l t p a v i n g materials.

R e g a r d i n g t h e s e c o n d , t h e p o t e n t i a l e n v i r o n m e n t a l e f f e c t s of t h e fumes t h a t are g e n e r a t e d from h e a t i n g r e c l a i m e d r u b b e r a t t h e mix ing t e m p e r a t u r e s re- q u i r e d f o r pav ing materials have y e t t o be i n v e s t i g a t e d by t h e New York S t a t e Depar tmen t s of E n v i r o n m e n t a l C o n s e r v a t i o n o r H e a l t h . L i k e w i s e , t h e h e a l t n e f f e c t s of c a r b o n b l a c k and o t h e r p o t e n t i a l c a r c i n o g e n s c o n t a i n e d i n t i r e r u b b e r have y e t t o be e v a l u a t e d .

Y

REFERENCES

1 . Assembly B i l l Number 7020-A, An A c t t o Amend t h e Highway L a w , i n R e l a t i o n t o t h e U t i l i z a t i o n of S c r a p Rubber i n t h e C o n s t r u c t i o n of Lnproveaen t s i n Highways, Yarch 2 6 , 1985.

2 . Cuomo, Y a r i o Y . , Veto Xessage No. 78, Assembly B i l l . Yo. 7 0 2 0 - ~ , August: 2 , 1985.

3 . Epps , J . A . "Seminar Summary," N a t i o n a l Seminar on A s p h a l t Rubber , San A n t o n i o , T e x a s , O c t o b e r 27-29, 1981.

. 4 . Teledyne N a t i o n a l , Assessment of t h e P o t e n t i a l f o r a Sys t em t o Recover Energy from S c r a p T i r e s i n New York, Vol . L ( u n p u b l i s h e d ) ; r e p o r t c d by Jewel Doug las , The Economics of L o c a t i n g a T i r e P y r o l y s i s P l a n i n New - York, ?iYS L e g i s l a t i v e Commission on S o l i d Waste Yanagement , Xay 1 3 d j .

5. N a t i o n a l Eco logy , I n c . , Assessment of t h e P o t e n t i a l f o r a Sys tem t o Re- c o v e r Energy f rom S c r a p Tires i n Sew York, Vol. 11 ( u n p u b l i s h e d ) ; re- p o r t e d and r e v i s e d by Douglas .

6 . F r e d e r i c k , D.A. S t r e s s - R e l i e v i n g I n t e r l a y e r s f o r B i tuminous R e s u r f a c - i n g s , R e s e a r c h Repor t 113 , E n g i n e e r i n g R e s e a r c h and Development Bureau , New York S t a t e Depar tment of T r a n s p o r t a t i o n , A p r i l 1984.

7. F r e d e r i c k , D.A. R e s e a r c h E n g i n e e r , E n g i n e e r i n g R e s e a r c h and Development Bureau , N e w York S t a t e Depar tment of T r a n s p o r t a t i o n , p e r s o n a l communi- c a t i o n .

8. Giles, K . E . and C l a r k , W.E. "Asphal t -Rubber I n t e r l a y e r s on R i g i d Pave- men t s i n New York S t a t e , " N a t i o n a l Semina r on A s p h a l t Rubber , San An- t o n i o , T e x a s , October 27-29, 1981.

9. C i n t h c r , 0. R e s e a r c h E n g i n e e r , New York S t a t e Thruway A u t h o r i t y , per- sonal communica t ion .

10. Anonymous, r e p o r t e d i n R e f e r e n c e 8.

11. Esch , D.C., A s p h a l t Pavements Modi f i ed w i t h Coarse Rubber P a r t i c l e s , Repor t No. FHWA-AK-R1)-85-d7, D i v i s i o n of P l a n n i n g and R e s e a r c h , A l a s k a S t a t e Depar tment o f T r a n s p o r t a t i o n , Augus t 1984.

-- 12 . S h u l e r , T.S., P a v l o v i c h , R .D. , Epps , J. .4 . , and Adams, C.K. L n v e s t i g a t i o n

of Materials and S t r u c t u r a l P r o p e r t i e s of Asphal t -Rubber Pav ing Y i x t u r e s , r e p o r t on work c o n d u c t e d unde r C o n t r a c t DTFH 61-82-C-0074 t o t h e United S t a t e s Depar tment of T r a n s p o r t a t i o n , F e d e r a l Highway A d m i n i s t r a t i o n , ( 1985, u n p u b l i s h e d ) .

1 3 .

14

15.

16

17.

18.

S c h n o r s e i e r , R.H. " T i m e P roves Xsphal t -Rubber S e a l s C o s t E f f e c t i v e . " N a t i o n a l Seminar on Aspha l t -Rubber , San A n t o n i o , T e x a s , O c t o b e r 2 7 - 2 9 , 1981.

Gup ta , P.K. Asphal t -Rubber S u r f a c e T r e a t m e n t s and L n c e r l a y e r s , Resea rch Repor t 130, E n g i n e e r i n g Resea rch and Development Bureau , New York S t a t e Depar tment of T r a n s p o r t a t i o n , December 1985, ( i n p r e s s ) .

F e d e r a l R e g i s t e r , Vol. 51 , No. 3 4 , F e b r u a r y 20, 1985 ( p a g e 62U2) .

Letter t o Docket C l e r k (Docket No. 6002 , Asphal t -Rubber P rocuremen t G u i d e l i n e ) , O f f i c e of S o l i d Waste, WH-565A, U.S. Envi ronmen ta l P r o t e c t i o n Agency, Wash ing ton , DC 20460, f rom John K. X l a d i n o v , E x e c u t i v e Deputy Commiss ioner , N e w York S t a t e Depar tment of T r a n s p o r t a t i o n , d a t e d A p r i l 18 , 1986.

Le t te r to Docket C l e r k from Ray B a r n h a r t , A d m i n i s t r a t o r , F e d e r a l Hignway A d m i n i s t r a t i o n , d a t e d A p r i l 2 2 , 1986.