Laserfiche WebLink
Mr. Peter MacNicholl <br /> 6/12/2007 <br /> Page 5 <br /> 9. Section 3.4.2.7 The two cross sections suggest that there are substantial <br /> variations in vertical anisotropy, mainly associated with sediment type. A figure <br /> showing, for example, the relation of vertical anisotropy to hydraulic conductivity <br /> (based on the data in Table 4-1) would help illustrate this. The concern is that <br /> the anisotropy appears to be smaller in some of the high and very high K areas <br /> of Figures 2-6 and 2-7. <br /> Section 4. <br /> 1. Section 4.1.5 discusses "Head" not "Flow", and should be revised. <br /> 2. Section 4.2.8 The small % difference in the totals is a trivial consequence of <br /> using general head boundaries, and does not indicate that the model accurately <br /> reflects the domain's water balance. Errors in subsurface inflow and outflow <br /> disappear because they are subsumed into conductivity adjustments. The total <br /> subsurface inflow to the model at the upgradient end should be checked against <br /> the area, conductivity and gradient for reasonableness and consistency. A <br /> defined-flux boundary might be a safer alternative, at least for subsurface inflow. <br /> 3. Section 4.3.0.3 A cell-by-by cell and layer-by-layer water balance to identify <br /> cells with unusual vertical or horizontal flow rates is requested. Simple <br /> spreadsheet-like tables are acceptable. <br /> 4. Section 4.3.5 Since hydraulic conductivity varies over two or three orders of <br /> magnitude, a 10% variation does not represent the full impact of uncertainty in <br /> conductivity. If an order of magnitude is used, the model's sensitivity to K will <br /> increase. The use of a 10%Variation should be justified. <br /> 5. Table 4.2 Please add columns for acre-feet per year, and separate general <br /> heads into subsurface inflow and subsurface outflow. <br /> Section 5. <br /> 1. Section 5.4.2. The relation, if any, between clay/silt fraction and total organic <br /> carbon, both in observed and modeled conditions, should be mentioned and <br /> illustrated with a figure. The linkage made between TOC and hydraulic <br /> conductivity built into the model makes it difficult to untangle their separate <br /> effects during calibration. <br /> 2. Section 5.2.2.3. The interaction of dieldrin with solvents, and the impact of <br /> wastewater on FOC should be mentioned as a confounding factor in deciding on <br /> a carbon-water partition coefficient. <br />