Over-application, field trials

Field Application. Field trials of classical alkaline flooding have been disappointing. Mayer et al. (60) indicated that only 2 of 12 projects had significant incremental oil recovery North Ward Estes and Whittier with 6-8 and 5-7% pore volume, respectively. Estimated recovery from the Wilmington field was 14% with a classical alkaline flooding method (61). However, post-project evaluation of that field indicated no improvement over water-flooding (62). 

In field trials following multiple aerial applications of endosulfan for tsetse fly control in Africa over a 3-month period, residues of the compound in fish tissues decreased to low concentrations within 3 months after spraying. The fish tissue residues were still detectable after 12 months. Residue concentrations in fish-eating birds and crocodiles were similar to fish tissue residue levels endosulfan did not biomagnify in the food chain (HSDB 1999). 

Application of the test substance to the test system is without doubt the most critical step of the residue field trial. Under-application may be corrected, if possible and if approved by the Study Director, by making a follow-up application if the error becomes known shortly after the application has been made. Over-application errors can usually only be corrected by starting the trial again. The Study Director must be contacted as soon as an error of this nature is detected. Immediate communication allows for the most feasible options to be considered in resolving the error. If application errors are not detected at the time of the application, the samples from such a trial can easily become the source of undesirable variability when the final analysis results are known. Because the application is critical, the PI must calculate and verify the data that will constitute the application information for the trial. If the test substance weight, the spray volume, the delivery rate, the size of the plot, and the travel speed for the application are carefully determined and then validated prior to the application, problems will seldom arise. With the advent of new tools such as computers and hand-held calculators, the errors traditionally associated with applications to small plot trials should be minimized in the future. The following paragraphs outline some of the important considerations for each of the phases of the application. 

Over 30 months elapsed between the time AGS and Lindow notified EPA and the tests were conducted. The EPA review process for the notifications and EUP applications consumed about six months, and the applicants spent four to six months developing additional data requested by EPA. The remaining 18 to 20 months were consumed by efforts to resolve legal challenges mounted against both EPA and the applicants in an effort to prevent the field trials. Table I... 

SHRP undertook a field trial in collaboration with Ontario Ministry of Transportation to see if ASR can be controlled by the application of lithium ions in the electrolyte. These ions (Li") move towards the rebar under the influence of the electric field. Lithium is known to reduce or stop ASR and has proved effective in lab tests. If a corroding structure is made with aggregates susceptible to ASR, a detailed inve.stigation of its likely reaction to treatment will be required. Monitoring of the Ontario bridge will continue over the next few years to see if the ASR is. suppressed (Manning and Ip, 1994). 

One decision still to be faced is to devise a test to indicate satisfactory performance over the intended life of the assembly. Fortunately, sufficient evidence has now been accumulated to enable manufacturers to give positive recommendations in most cases. Occasionally, on fringe applications, it is necessary to advocate long term field trials (see Chapter 6). 

The potential use of calcium magnesium acetate (CMA) has been extensively researched in North America, and field trials have been conducted in several states and provinces. The CMA specification in terms of composition, particle size and shape, color, and density has evolved over time. CMA application rates have generally been higher than those for salt. The majority of trials conducted have indicated effectiveness similar to that of salt at temperatures down to -5°C, but slower performance than salt at lower temperatures. Unfortunately, costs are reportedly more than 10 times higher than those of road salt on a mass basis. If a higher application rate of 1.5 times that of salt is assumed, a cost factor increase of 45 has been reported. Cost issues surrounding the use of CMA are complex and include factors such as potential environmental benefits, reduced automobile corrosion, mass production technology, and alternative raw materials. 

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