Swell Tests conducted accordingto an Indian standard method indicate that much of the soil at the <br />site is significantlyexpansive (Free Swell results ranging from 30 to 50%, with 3 of 4 samples in the <br />35 - 50% high range) . Expansive soils require the presence of expansive clay minerals, and none <br />of the test pit logs make any mention of clay. The presence of clay is actually indicated in the USDA <br />Soil Survey, which indicates that the soil in the area where the test pits were excavated <br />(Philomath <br />soil, # 108) consists of Lean Clay (CL) and Fat Clay (CH) soil rather than Silty Sand (SM). <br /> conducted, the use of the field data for conclusions <br />As careless as the field work appears to have been <br />is even worse. All test pit logs indicate that the test pits ended in variably decomposed “sandstone”, <br />which is consistent with GeoScience observations. However, in the May 30, 2017 Addendum, on <br />th <br />page 1, 5 Paragraph, we find the following sentence: <br />“The test pits and observations showed the majority of the development site was underlain <br />by the stable volcanic rock material.” <br />Both the report with the test pit logs and the addendum arestamped by Ron Derrick. P.E., G.E., a <br />geotechnical engineer and Gary Sandstrom, a Certified Engineering Geologist. <br />It is unfathomable <br />to me how two professionals in the geologic/geotechnical field could classify sandstone as <br /> This is a Geology 101 question. <br />“volcanic rock”. <br />This incorrect classification may appear meaningless and without importance to a lay person, but in <br />reality, the rock type and structure at this site have a significant influence on the stability of the slope. <br />This is discussed further in the Section “Structural Geology and the Dip-Slope Failure Issue”, below. <br />Additional errors are found on the “Area Slope Hazard Map” presented byBranch Engineering with <br />the addendum on May 30, 2017. In the left-hand lower corner the map states: <br />“Scale: 1" = 1000' (8.5" x 11")” <br />The eastern boundary of the PUD is 2.43 inches long on the map. This would indicate that the PUD <br />extends 2,439' in a N-S direction. This is incorrect. The PUD is only around half that long. That <br />means that the actual scale of the map is apparently 1" = 500'. Of course that results in the landslides <br />mapped by DOGAMI to be twice as close to the PUD as the map purports with its scale. <br />Moreover, the “No Build” area on the map is significantly more inclusive than in the other PUD <br />plans. <br />Whereas the applicant’s “hazard map” shows that all of Lots 18 and 19 are to be <br />included in the “No Build” area, the PUD plans show buildable area in the upper half of the <br />. Given the steepness of the slope on these lots (up to 73% in the buildable area), the “No Build” <br />lots <br />designation appears appropriate. But non-conservatively, this was not considered in the PUD plans. <br />6 <br />Capital Hill PUD Geotechnical Review, GeoScience, Inc. 3/7/18 <br /> <br />