The Evaluation of DBCP in groundwater of the Kings Basin, Central Joaquin Valley California

Abstract

An evaluation of the distribution of DBCP in the aquifer was conducted within the Kings Groundwater Basin, Central San Joaquin Valley, California. The geographical distribution of DBCP coincides with locations of vineyards and orchards, and sandy soils. High DBCP concentrations are generally found above a depth of 250 feet, and DBCP is normally undetected below a depth of about 300 to 350 feet in the Kings Basin. Aquifer parameters and the direction and rate of lateral and vertical groundwater flow were analyzed for a number of subareas to determine the direction and migration rate of DBCP. The urban area pumping depressions accelerate the lateral flow of DBCP contaminated groundwater into the urban area. The geographical extent of DBCP has been observed to decrease considerably over time. The field half life of DBCP was found to be approximately six years for all factors involved in the degradation of the chemical. DBCP is expected to remain a serious groundwater contaminant that adversely affects the development of potable groundwater in the Kings Basin for one to two more decades.