COMPLIANCE INFO - Laserfiche WebLink

Home Browse Search

M ` A-C6 Analyses revealed that the gravel contained several pesticides at fairly high levels, including DDE at 22 ppm, DDD at 15 ppm, disulfoton (Di-Syston) at 250 ppm, and carbofuran at 38 ppm. The free-water sample also contained numerous pesticides, but generally at low levels. Carbofuran, however, was at 16 ppm. The 2"-6" soil composite contained a few pesticides including ethion at 110 ppm and ethyl parathion at 48 ppm. The 18"-24" soil com- posite showed only one pesticide, 2,4-0 at 0.16 ppm. No pesticides were detected in the well water sample. It is possible that the discolored gravel is part of an old leach field to disperse water from the pit in the wash area. In any event, some miti- gation will be necessary to prevent the off-site movement of pesticides in the shallow ground water. Some mitigation may also be necessary in areas where surface soils have significant pesticide residues, but additional sampling is necessary to define the areas, and a -review of site soils and hydrogeology is necessary to determine the degree of protection afforded by site specific conditions. 11. This aerial applicator facility has been in use since 1947. The current operator' s family obtained the facility in the 1950' s and he has been operating there since 1960. Washing is done on a concrete pad sloped to a ditch which discharges onto an agricultural field approximately 1/4 mile from the wash pad. The facility operator owns the agricultural field. Approximately 100 yards of the ditch had discolored soils. There was a burn-pit for solid waste a few yards from the ditch. Two composite soil samples were collected from the first 25 yards of the ditch. One consisted of 5 samples from 0-6". The other consisted of 2 samples from 18"-24". Analyses revealed high levels of several pesticides in the 0-6" sample, including endosulfan at 1390 ppm, DDT at 490 ppm, ethion at 94 ppm and carbofuran at 12 ppm. The pesticides were signifi- cantly attenuated by the soil , but at 18"-24", DDT was still 76 ppm. Water from equipment washing comes from a cistern supplied by the Delta Mendota Canal . The cistern is designed to prevent a backflow to the supply canal . There is a well at the facility which extends to 500 feet; the water is not potable due to high salts . A sample of the well water collected from a hose bib was checked for pesticides and 4 ppb of 2,4 0 was reported. A second sample was collected adjacent to the pressure tank and no 2,4 D was detected. The degree of threat posed by the existing residues needs to be determined. More soil testing is necessary to define the areal and vertical extent of the residues of concern. The operator has indicated that to construct additional rinse water facilities such as above•-ground tanks, would impose a severe financial burden. It is doubtful that he could construct such facilities and also do any significant site characterization and cleanup.