COMPLIANCE INFO - Laserfiche WebLink

Home Browse Search

A-C3 The facility operator stated that he is field-rinsing airplane spray tanks and that the only wash water generated on-site is from exterior washing of airplanes. He indicated that unless it is shown that his current practices pose an environmental threat, he is reluctant to change them. Sv 6. This aerial applicator facility in County utilizes a compacted gravel wash area adjacent to a loading area at the end of the runway. Rinse water is directed to a surface impoundment constructed in 1981 after consultation with CVRWQCB staff; permeability testing had been done to show that the standard in pesticide rinse water guidelines (1x10'8 cm/sec or less) was met. Prior to construction of the impoundment, rinse water was directed to Morrison Slough and thence to the Sutter Bypass. During intense rainstorms , especially in wet years, the site is subject to flooding, and the adequacy of protection of the impoundment is not known. There are two additional site features that raise concerns for water quality protection from site activities. One, runoff from the loading area is directed to a drain that discharges to Morrison Slough. Soil dis- coloration in the loading area indicates a potential for adverse surface water impacts from this area. Two, the well that supplies water for equipment washing and pesticide dilution is located under the load- ing/washing area. The area has a high perched water table and there is a potential for the well to act as a conduit for pesticide movement to ground water. Samples of the well water were collected and found to contain pesticides . Resampling confirmed the presence of molinate (Ordram) , thiobencarb (Bolero) , simazine, and diuron. Methyl parathion, methiocarb, methomyl (tannate) , 2,4,5 TP, and monuron were not confirmed but were detected in one sample. Two soil samples were collected from the rinse water impoundment: a composite of 5 samples collected at 0-6"and a composite of 2 samples collected from 18"-24". Soil below 6" was very hard clay. Analyses revealed that all but two of the pesticides detected in the surface soil were at low levels. Thiobencarb (Bolero) was at 58 ppm and total copper was at 25,800 ppm. At 18"-24" the thiobencarb was 0.36 ppm and copper was 50 ppm, both showing very high attenuation by site soils. After the initial well water samples tested positive for pesticides, two residential wells located within a quarter mile of the facility in the general direction of ground water, flow were sampled. No well logs were available, but the owner of one well indicated that it drew from less than 40 feet. No pesticides were detected in either well (all six available pesticide scans were run on samples from each well ) . 7. This aerial applicator facility has a concrete wash ��rea that discharges to an enlarged section of an area drain. The area drain has flow only during portions of the rainy season, at which time it discharges indirectly to the Colusa Basin Drain. During the spring and summer , the enlarged section appears to be a pond. The "pond" dries up by fall . The facility location is subject to flooding during the winter, and pesticide residues which might be present in the loading area are then subject to dischar e iii� the area drain. 1