WORK PLANS - Laserfiche WebLink

Home Browse Search

' C-SHADRIFS.6/WPADD.12 05/24/90 The arsenic source materials are either naturally occurring arsenic- enriched minerals or arsenic-bearing anthropogenic materials. The ' secondary minerals most likely are minerals with arsenic substitution or exchange capacity. The following statements present evaluations of the possible restrictions on the nature of the arsenic source material. ' 1. If the sources are naturally occurring arsenic-enriched minerals, the distribution might be expected to be more homogeneous rather than restricted to approximately 15 percent of the wells and only the A-zone aquifer. 2. If arsenic-bearing chemicals (anthropogenic materials such as rodenticides) are the primary source, either they were washed through the overlying sediments and are currently located within the aquifer or they are being dissolved and transported into the aquifer by infiltrating surface water. In the latter case, a secondary mineral capable of taking up the ' dissolved arsenic is required to buffer the arsenic at the observed concentrations. Identification of these solid phases requires collecting sufficient quantities of soils at the surface, the aquifer, ' the zones immediately above and below the aquifer to yield an adequate amount of arsenic-bearing material for identification. 1 To attempt to acquire these arsenic-rich source materials for positive identification, the following samples and analyses are required: 1. Ten samples of soils from drainage ways in the vicinity of well 407A; ' 2. Ten samples collected from dry well sediments in the vicinity of well 407A; ' 3. Five samples of A-zone aquifer soils in the vicinity of well 407A; 12 1