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Home My WebLink AboutNCD980602163_19791116_Warren County PCB Landfill_SERB C_Smith Patterson letter re additional testing-OCRNORMAN ■.SMITH SMITH, PATTERSON, FOLLIN,CURTIS,JAMES & HARKAVY ATTORNEYS ANO COUNSELLORS AT LAW 70-4 SOUTHE:ASTCi.N aUILDING GREENSBORO, NORTH CAROLINA 21•01 TIE:Lltl"HONIE: (919) 27• ·2992 * AALEIOH OFFICE HENRY N. PATTERSON, .JR.* MARION G. ,-OLLIN Ill MICHAEL K. CURTIS •07 RALIE:lGH BUILDING S WEST HARGETT STREET RALIE:IGH, NORTH CAROLINA 2,eo1 TCLE19HONIE (819) 795-1812 J . DAVID .JAMES JONATHAN Ill. HARKAVY CHARLIE:S A. LLOYO THOMAS W. ROSS NAHOMI HARKAVY November 16, 1979 JOHN R .KERNODLE,.JR MELINDA LAWRIE:NCE * Mr. w. A. Raney, Jr. Special Deputy Attorney General State of North Carolina Department of Justice P. o. Box 629 Raleigh, North Carolina 27602 Dear Bill: We have gotten from our consultant the additional testing that he wants to have done at the site. The work he wants to de, is: (1) Detail Soil Profile Map. A detail soil map of the sub- surface horizons of the entire excavation area at the site needs to be prepared. This will invo!vetaking a surface map for the area and dividing the excavation area into a 100 x 100 ft. grid. At each point on the grid, a detail description of the horizon layers from the surface to "C" or parent material is to be made. This would be done at six inch intervals with accurate measurements of the thiclcn~of each layer. From my observations of the soils at the site, the clay enriched material or layers will be within the initial 24 to 48 inches. (2) Using 3 -dimensional graph paper, the variability of the thickness of the horizon layers at the site can be mapped appropriately. This will enable the site con- struction engineers to very accurately remove those layers which have the clay contents and physical parameters m~eting the requirements stated in EPA guidelines for the clay liner construction. Ph!sical Proper·tt Evaluations. Samples of soil are to be co lected from t e respective horizons at the various points on the grid. These are to be quickly enclosed in sealed containers for moisture determinations in the lab. After moisture determinations (based on oven dry weight) a complete mechanical analysis of the sand, silt and clay contents are to be performed. Clay contents will be de- termined using pipette techniques and will include solids ~ 0.002 mm in size. (The Soil Science Society of America defines c.Lays as solid soil particles < 0. 002 mm in size) • The State•~ consultant reports for the Warren County site £Raney, Jr. 't>age -2- November 16, 1979 have used<:.. 0.005 mm as the clay fraction which has re- sulted in the appearance of about twice the clay content as actually resides at the site. The EPA is their haste to approve the site failed to catch this shift in clay definition. In my judgment, due to the absorptive nature of PCB on clays, the definition used by the Soil Science Society of America should be the standard. The smaller the particle, the higher the surface area. The higher the sur- face area, the higher the absorption capacity of the material.- Also, the higher the surface area, the greater the chemical exchange capacity of the soil. Therefore, for these reasons, the 0.002 rather than 0.005 mm should be the standard for clays used in liners for chemical dump sites. Having mechani- cal analysis data, the horizon layers can be assigned into appropriate textural classes. Those horizons exhibiting clay enrichment should be examined for permeability and other parameters specified by EPA. Again, samples of soil from the various grid points will be examined. Only those soil horizons which show <1 x l0-7cm/sec permeability under 80% compaction should be considered for the clay liner. The permeability values and other soil p~ysical property parameters for the various individual horizons should be subjected to statistical eval- uations to compute mean, standard deviation and coefficient of variability estimates. This will give the engineers a clear pattern of which soil horizons may be combined or mixed during the liner construction and safely remain within the EPA guidelines. An 80% compaction to achieve the desired permeability standard of ~l x l0-7cm/sec is recommended since assured quality control involving higher compaction will be diffi- cult to attain under field conditions. Since soils typically contain 50% air and 50% solids by volume, and that soil moisture will occupy a portion of the air space, if a 95% or 100% compaction were required to a~tain a permeability of< 1 x l0-7cm/sec, the variation in the soil moisture con- tents may make it very difficult to meet the EPA require- ments under field conditions. Thus, the liner may not have uniform resistance to moisture flow under such marginal con- ditions. If these parameters cannot be met, the site should be dropped from consideration. Since the excavation area will involve a number of acres and since it will be impossible to control rainfall, surface water, etc. in such a large area during the site preparation, the more conservation value of 80% compaction rather than 95 to 100% should be selected. Only that soil material which meets this rigid standard should be considered for the liner. Mr. W. A. Raney, Jr. Page -3 - November 16, 1979 Please let me know what assistance the State of North Carolina would be willing to give us in connection with these procedures. NBS/mlb cc: Dr. Charles Mulchi Mr. Charles Johnson Yours sincerely, c~O('d Norman B. Smith