Laserfiche WebLink
David Wang <br /> Page 7 <br /> the RI report. DHS also suggests that more detail be provided <br /> in the report regarding the subject sandy clay layer such as its <br /> thickness and lateral extent. <br /> 5) Section 3 . 4 . 4 . 6 Groundwater Sampling of Monitoring Wells <br /> under SOW Task 30 paragraph 3 . 4 . 4 . 6. 2 , pages 3-23 and 3-24 : <br /> The RI report states that PCE concentrations in LM24 have <br /> decreased from 760 ppb in 1986 to 20 ppb in 1988 . <br /> The RI report should provide an explanation for this decrease in <br /> PCE. <br /> MINOR COMMENTS AND CLARIFICATION REQUESTS: <br /> 1) Section 3 . 3 . 1, Geologic Cross-Sections) page 3-14 , <br /> paragraph 3 . 3 . 3 . 1, lines 12 , 13 , and 14 : <br /> The RI report states: <br /> "Great variability with respect to grain size and competency <br /> (percentage of clay) occur throughout the lateral extent of <br /> each lithologic unit. " <br /> The word `competency' has been misused in this sentence. <br /> 2) Section 3 . 3 . 2 , Local Geology, page 3 . 13 , paragraph <br /> 3 . 3 . 2 . 3 , lines 3 and 4 : <br /> The RI report states that the Corcoran Clay is found to be <br /> thickest in the Tracy area, where it is typically at least 120 <br /> feet thick. DHS requests a published reference for this <br /> statement. <br /> 3) Section 3 . 4 . 3 , Existing Groundwater Quality page 3-17, <br /> paragraph 3 . 4 . 3 . 1, line 6: <br /> The RI report refers to the "Old River" . The "Old River" <br /> referred to has not been defined nor its location indicated. <br /> The "Old River" should have been mentioned in Section 3 . 4 . 1 <br /> (Regional Hydrologic Setting) which mentioned the principal <br /> tributary stream systems. DHS requests clarification as to the <br /> definition, location, and nature of the "Old River" . <br /> 4) Section 3 . 4 . 4 . 4 , Part 1 Groundwater Monitoring Wells page <br /> 3-19, paragraph 3 . 4 . 4 . 4 . 2 , lines 10 through 13 : <br /> The RI report states: <br />