Document kD4rpmGp90KzXnZ6gpRXNKQE0

BEFORE BECOMING DATE PPM OP PCB mm '^Lll--i `wU------)- x -- ----- UTTER RECOATING MATERIAL PPM OF PCB DATE PPM OF PCB Silage 0.132 6-28-72 DATE ------ "W------------- O 2 (O o * 5-3-72 20,155.000 Scrapings -------- 'To'---------- ----- ----------- ----------- ' 19 -- 5-3-72 -5-3-72 7,131.885 103.017 Silage Silace 1. Silo vas built and coated with a material that con tained PCBs in 1957. 2. The silo cleaned with a wire brush* coating was ThorosealR hydarulic cement with an Acryl-60R bonder on 6-5-72. - Standard Dry Wall Inc., Miami, Florida Silage Silage Silage Silage Silage Silage 0.128 0.081 0.271 7-26-72 8-9-72 8-18-72 0.061 0.051 0.065 0.020 0.072 11-250 12-16-72 12-27-72 1-10-73 1-23-73 Silage Silage 0.382 0.424 8-29-72 9-12-72 0.080 0.099 2-3-73 2-16-73 Silage Silage 0.237 0.286 9-26-72 10-10-72 3. The silo was filled with chopped grass 6-17-72 and opened 6-24-72 4. The silo was refilled with chopped corn in late October 1972. w THE DECONTAMINATION OF SILOS CONTAMINATED WITH POLYCHLORINATED BIPHENYLS (PCBs) SOME IMPORTANT CONSIDERATIONS 1. Concrete alios, whether of poured or stave construction are porous and are subject to attack by the organic acids pro duced during the ensiling process. 2. For many years various coating materials have been used to lessen this erosion of the silo wall. Generally these coatings have taken the form of: A. An"expendable" concrete plaster. B. A material to fill the pores in the concrete which re duced the surface subject to acid attack. C. Aid barrier coatings which prevent the contact of organic acids with the silo wall. 3. One such barrier coating was "Cumar", which contained poly chlorinated biphenyls and terphenyls. This material was first used in the early 1940's, with application as a protection for the grouting between stave blocks and as a coating. A. When "Cumar" was applied to the silo wall the solvents of the coating penetrated into the concrete, thus carrying the PCB and PCT residues into the silo wall. After the "Cumar" cured there would not appear to be any impetus for further migration of the residue. B. When the silo was filled the organic acids produced, dissolved some of the PCB from the "Cumar" coating thus contaminating the silage. Then this PCB residue diffused through the silage away from the silo wall. C. With time, failure of the "Cumar" coating occurred and flakes of this material, which fall into the silage, caused localized areas to become highly contaminated. D. In areas where the "Cumar" had failed or had completely come off the wall, the organic acids from the silage have now penetrated into the pores of the silo wall and dissolved some of the PCB residues. These resi dues then are diffused into the silage. Silos, last coated with a PCB containing coating 16 years ago, and long after all traces of the coating were gone, may still cause significant contamination of the silage. HONS 044241 -2- 4. Cleaning the surface of a PCB contaminated silo and recoating the surface with a material that will prevent contact between the silage acids and the concrete walls that are PCB contami nated, has been demonstrated to be an effective decontami nation method. Where this method was not as positive for removal of the residue as would be destruction and removal of the structure; time, expense and convenience have made recoating a more practical approach. 5. If a silo is to be decontaminated by recoating it must be remembered that no coating will be any better than the sur face upon which it is applied. Therefore, dirt, particles of an old coating and/or a deteriorating surface must be removed. A. Sandblasting is an excellent method to prepare a sound silo surface upon which a new coating can be applied. When this method is used care should be taken to con trol the dust, debris and sand as these can spread PCB contamination to other areas of the farm. The expense involved with sandblasting makes this approach im practical under most circumstances. B. Washing the surface with high-pressure water (500 psi) has proven to be an effective means to clean the silo walls. When this method is used the runoff must be controlled to prevent PCB contamination of waterways. Time for the silo walls to dry must also be considered when water is used. This is particularly important in the winter when frost may build in the silo walls, thus preventing good bonding of the coating. C. Wire brushing of the silo surface is also effective but is dirty work that requires a great deal of time and labor. D. Preparation of a silo for recoating, that still has the "Cumar* coating intact, presents a special problem. Unless this "Cumar* is removed or a rough surface pre pared the chances of a good bonding of the new coating are greatly reduced. The "Cumar" should never be re moved with an organic solvent, as this method will spread the PCB contamination and may leave the surface unfit for recoating. With solvents there is the danger of fire and/or toxic vapors. Sandblasting may be the best way to remove an intact "Cumar" coating. 6. The coating used as a barrier to PCBs must be a specialized product to withstand the harsh environment inside a silo, plus prevent the acids in silage juices from reaching the silo wall. Some of these coating properties are listed be low. MQNS 044242 -3A. The co'ating must bond well to concrete. B. It must be waterproof, nonporous and cover completely. C. It must be acid resistant as pH values as low as 3.5 are encountered. D. Temperature ranges from below freezing to 160 F must be withstood without failure. E. It should be tough so that machinery, such as unloaders, don't cause it to flake off. F. The coating should not contain chlorinated hydrocarbons or toxic chemicals that will contaminate the silage. G. The coating should meet the Occupational Safety and Health Act (OSHA) standards to protect the workers applyinq the material from toxic or flammable vapors. Likewise, the product will need to meet local air pollution control regulations. H. The coating should not contain a solvent in which PCB is readily soluble, as PCBs from the silo wall may become a component of the new coating. I. Application of the material should be uncomplicated. J. The cost of the coating should be low enough so that the entire recoating operation does not exceed 20% of the cost to replace the silo. L. B. Willett, April 1973. MONS DATE PPM OF PCB MATERIAL MATERIAL AFTER RECQATING PPM OF PCB DATE PPM OF PCB DATE HONS 9-7-72 314.017 Scrapings 7-5-72 7-5-72 9-7-72 9-7-72 5.111 8.037 175.365 705.236 Silage Silage Scrapings Scrapings 6-19-70 6-19-70 9-9-70 0.987 0.033 4.900 Silage Silage Scrapings 9-9-70 3.600 Scrapings 4\ !______________________I 1. Silo was built and coated with a material that contained PCBs in 1954. 2. In 1966 lower 8 feet and the pit were coated with Silenzcrete, Universal Cooperatives, Alliance, Ohio. Silage Silage Silage Silage Silage Silage Silage Sila9* Silage Silage Silage 20.677 52.536 58.997 28.798 1.909 1.171 0.855 0.843 1.062 ''-0-569 1.007 10-30-72 11-7-72 11-10-72 11-16-72 11-22-72 11-30-72 12-5-72 12-8-72 12-19-72 12-22-72 1-5-73 13.433 18.225 1.311 0.693 0.403 2-27-73 3-2-73 3-6-73 3-12-73 3-16-73 Silage Silage Silage Silage Silage Silage 0.883 0.615 0.351 0.373 0.481 1.564 1-9-73 1-12-73 1-19-73 3. On 9-16-72 the silo was cleaned and recoated with Water based Epoxy - Action! Plastic# Inc. Charlotte# Michigan; fron the 1 base of the pit to 37 feet above ground level. .F 4. The silo was filled with chopped corn 10-5-72 and was opened ? f 10-30-72 ;J 5. The silo was filled with corn silage from stack silo 2-9-73. ; il ES SILO 8-10-1972 History Hiohlgan Silo 14 X 50 Built Coated Cumar Qlazed Concrete plaster 1958 1958 1967 1970 (30 ft) Condition Plaster ooatlng was bard axoapt for blisters where the surfaoe was not adequately oleaned. The silo was not adequately oleaned before plastering. The Cumar was not visible above the concrete plaster. Comments ------The operator has not fed from this silo for one year because hewaB afraid of possible FCB contamination. Thus the silo was filled only once since the plaater- 00ating was applied. Has two other silos available that he now uses. PCB levels. (Aroolor 125ti) Scraping of piaster surfaoe Soraplng where plaster failed Soraplng above plaster Silage adjaoent to wall Milk from bulk tank 1.014 ppm 178.079 ppm 304.755 ppm 33.603 ppm 0.028 ppm L. B. Willett January 1973 MONS 044245 BEFORE RECOATXMG PPM or PCB MATERIAL rffim ii-ui-*--.1 i37i--ll---L AFTER RECOATIWG MATERIAL PPM OF PCS DATE PPM OF PCB ram Silage 0.132 6-28-72 SNOW -----"V ---nr--------- 5-3-72 20,155.000 Scrapings -- -- .--. -- i& - -- 5-3-72 5-3-72 7,131.885 103.017 Silage Silaae 1. Silo was built and coated with < tained PCBs in 1957. 2. The silo cleaned with a wire bn coating vas Thoro*ealR hydarulic cement with an *Acryl-60R bonder on 6-5-72. - Standard Dry Wail Inc., Miami, Florida Silage Silage Silage Silage Silage Silage Silage Silage 0.128 0.081 0.271 7-26-72 , 8-9-72 8-18-72 0.382 0.424 8-29-72 9-12-72 0.061 0.051 0.065 0.020 0.072 0.080 0.099 11-2S 12-16-72 12-27-72 i-lO-73 1-23-73 2-3-73 2-16-73 Silage Silage 0.237 0.286 9-26-72 10-10-72 3. The silo was filled with chopped grass 6-17-72 and opened 6-24-72 4. The silo was refilled with chopped corn in late October 1972.