Abstract

Methyl tertiary butyl ether (MTBE) groundwater contamination problem has become a significant issue since the Santa Monica Charnock wellfield was shut down in 1996 due to MTBE contamination. To deal with this problem, the regulatory and scientific communities recognize the need to collect more data and conduct further study of MTBE. As part of these efforts, MTBE data of the vertical concentration distribution in the aquifer and the statistical analysis of these data are presented. The data of MTBE concentration vertical distribution is not commonly obtained during a regular site assessment. One of the purposes of this article is to present data of this type. The data for the MTBE vertical plume length analysis were obtained from a total of 22 groundwater sampling locations and 115 discrete-depth data points at the shallow and deep aquifers within the Charnock wellfield investigation area, Santa Monica, California. The data suggest that MTBE migration occurs vertically as well. MTBE concentration decreases ~92% on the average of the detectable cases at the shallow and the deep groundwater. The correlation coefficient indicates that MTBE concentration has a moderate correlation with benzene concentration in the vertical distribution. This may suggest that the MTBE plume is not much faster than is the benzene plume in the vertical direction. MTBE concentration has a poor correlation with soil type. Analysis of variance (ANOVA) indicates that MTBE detected in a sandy or gravel formation aquifer is not statistically significantly different from that detected in a fine-grained material formation aquifer.