LETTERS Dredging Dear Sir: The April issue of €S&T contained three articles (pp 326-338) on dredged material regulation and research. In view of the National Wildlife Federation’s considerable interest in this subject, we are moved to offer the following comments. The articles by Lee and Smith point up one of the biggest problems in disposing of dredged material in a way that satisfies legal requirements and environmental protection concerns. As Lee indicates, “what is needed is a procedure by which the potential significance of chemical contaminants in dredged sediments can be assessed prior to dredged material disposal.” Implications for both water quality and ecological and biological integrity need to be evaluated. Yet, the existing EPA guidelines under section 404 of P.L. 92-500 and the ocean dumping criteria under P.L. 92-532 fall far short of prescribing procedures for assuring that these environmental implications are addressed, much less addressed adequately. Thus, an “elutriate” test is provided for which, at most, tells one how
much of various “major constituents” will be released from the dredge spoil into the water column over the relatively short term. As Smith notes, ”benthic species can ingest contaminated sediment particles,” and can become contaminated or poisoned without any escape of major constituents into the water at all. Furthermore, it is now well known that certain heavy metals (e.g., mercury, arsenic, lead, selenium, and tin) can be methylated into more soluble and more toxic forms in the environment as a result of biological activity. Such transformations would never be detected in any elutriate analysis. To add insult to injury, dredged or fill material may be excluded from even elutriate procedures if certain less-exacting qualitative requirements have been met. To be sure, the kinds of bioassay and other characterization procedures necessary to adequately evaluate environmental consequences of dredge disposal often lie near the limits of the present state-of-the-art. However, there are “worst-case” assumptions that can be made to assure necessary protection to the environment. When the state-of-theart improves, case-by-case evaluations
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may be more reliable and disposal restrictions can perhaps be lightened. The reverse approach-of applying loose restrictions until and unless state-of-theart improvements indicate otherwisewill not protect the environment and is contrary to the law of the land. We cannot agree with Lee that more field studies are the answer, at least for the foreseeable future. As was noted recently by a British scientist (New Scientist, April 29, 1976, pp 219-221): “Present survey strategies appear to be based on such inadequate theoretical frameworks that they cannot possibly interpret subtle environmental changes. An understanding of these effects will require detailed study of biological interactionsover many years. Short-term, on-off “impact” statements or “base-line surveys” cannot be expected to provide an adequate framework for monitoring environmental changes.” We’d prefer to place our trust for the interim in laboratory and in situ bioassays, coupled with a healthy dash of respect for basic ecological principles. Kenneth S. Kamlet, Counsel National Wildlife Federation Washington, D.C. 20036
Groundwater Dear Sir: I read with much interest and great disappointment the article “Quality Assurance for Groundwater” ( E S T , March 1976, p 226). My interest in groundwater protection parallels much of what was expressed throughout the first half of the article. Certainly, groundwaters that lend themselves for public use need to be protected from pollutants and contaminants that may threaten human health. However, in the latter half of the article mention is made of human and animal wastes, and enteric viruses from human wastes being detected in groundwater supplies. Additionally, it was noted that “the major source of these viruses turned out to be leachates from sanitary landfills in which many disposable diapers containing untreated fecal matter had been buried”. There is much confusion and misunderstanding regarding land disposal sites. Unfortunately, many individuals fail to distinguish among the types of waste disposal sites-for example, dump, covered landfills, and engineered sanitary landfills. My disappointment and alarm stems from the fact that the author himself or the spokesman from the EPA Office of Water Supply implies that the disposable diapers containing untreated fecal matter gave rise to enteric viruses that resulted from leachates generated in a sanitary landfill site-with emphasis on the term “sanitary”. I question whether the site was indeed a sanitary landfill site or whether it was an improperly operated waste disposal site. In the absence of clarification and with the emphasis on “sanitary” it almost seems as if the author is taking a “cheap shot” at sanitary landfilling-a necessary approach for effectively managing our discards. NSWMA as the professional trade as-
sociation for the solid waste management industry has strongly supported sanitary landfill as an environmentally acceptable method of waste disposal. Therefore, it is imperative that those proficient in this field clearly differentiate between what constitutes a sanitary landfill versus an open dump. James R. Greco National Solid Wastes Management Assn. Washington, D.C. 20036
Opacity Dear Sir: We were appalled by the feature article, "Factors InfluencingPlume Opacity" ( E S T , June 1976, p 539). We did not realize that scientific facts could be juxtaposed in such a way to so thoroughly misrepresent the true situation. This article attempts to show that the use of visual opacity observations by control agencies for quantitation of particulate emissions is an invalid technique. We fail to grasp the purpose of the article because, in our opinion, no responsible control agency, certainly not the Texas Air Control Board, would attempt to enforce a mass emission regulation by such means. We have researched most of the available literature relating opacity and particulateconcentration,and have yet to see a technique proposed that involves dependence upon human observers. Considerable field work has been per-
formed in both Europe and the U.S. relating in situ opacity by transmissometer to particulate concentration. Good correlations have been established for cement plants, lignite-fired boilers, and other source types. The article appears to be directed toward visual observers. Yet as a starting point the authors use the EPA work with transmissometers on opacity/mass correlations for an asphalt concrete plant. They extrapolate from this study to find a "black dot" equivalent opacity for power plants. Anybody who is at all expert in the field knows that mass correlation with opacity must be done on a process by process basis. The authors are mistaken in their assumption that opacity mass data for an asphalt concrete plant can be extrapolated to a predicted opacity for a coal-fired power plant at a similar concentration. Generally, correlations must be established for each individual source, the validity of the correl&ion dependent on process variables and degree of emission control. A highly controlled continuous process is likely to have particle characteristics sufficiently stable to permit mass determination by transmissometry. New Source Performance Standards requiring more efficient particulate control devices will expand the range and number of sources to which an opacity/mass correlation may apply. Enforcing mass emission standards with opacity measurements is not difficult
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to justify on a technical basis as the authors claim, providing a method is chosen incorporating the best available technology applied with a full consideration of source characteristics that may bias the results. At worst, such a techn.ique will provide a continuous indication of mass emission rate at nominal additional expense where opacity monitoring requirements already exist. We must also take exception to the authors' implications regarding the inability of trained observers to accurately assess plume opacity. An EPA contract study by Southwest Research Institute (Hamil, et al. ref. 2) has verified the accuracy of visual observations on three types of sources with an accuracy greater than that specified in Method 9. They also neglected to mention that Connor's work was used as the basis of establishing opacity observer procedures so that observations will tend to be low. This is verified in the Hamil study and confirms our own investigation of our agency's visual observer certifications. As for the "problem" of uncombined water, it is a simple matter for trained observers to determine the point in the plume at which water ceases to be a factor in the opacity and evaluate it at that point. This technique, while perhaps not "scientific" in the sense that the authors are seeking, has produced good results in Texas. Visual observation of plume opacity serves most importantly as a rapid indi-
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Volume 10, Number 9, September 1976 847
