Item C: Delta Sand and Gravel Metro Plan Amendment

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specifications for sodium sulfate soundness exist only for portland cement concrete (PCC) and Asphalt Concrete (AC Aggregate). The appropriate Test Method is identified as ODOT TM 206. This test method was used by the applicant. The applicant’s report included studies conducted for the applicant by EGR & Associates, Inc. The original sampling methodology is described in Exhibit 1, Evaluation of Aggregate Resources: Delta Sand and Gravel Expansion Area, by EGR & Associates (June 2005). Issues raised under the quality criterion include: ?adequacy of methodology used to test the material ?adequacy of bore hole coverage ?adequacy of the data recorded from the samples taken A copy of the EGR report was attached as an exhibit to the application. EGR’s data draws on general geology studies; three borings conducted in 2004, two that were 81 feet deep and one 94 feet deep; well logs; a sampling of Delta Sand and Gravel’s west pit wall, which borders the subject site’s eastern perimeter with a height of approximately 65 feet, and on past excavation to a depth of 100+ feet on an adjoining site, previously permitted for gravel extraction. EGR confirmed the existence of Class II loam, sandy loam, and clay loam soils on approximately 75 percent of the expansion site. Aggregate resources could be found to an average depth of 70.5 feet. Samples of the gravel from the three boring holes and the pit wall (taken at 5 foot intervals) were analyzed in a laboratory for compliance with ODOT specifications. One representative composite aggregate sample for each sample site was provided by combining samples from the upper, Exhibit 1 middle, and bottom zones (). Two size distributions were obtained of the samples. Tests conducted by Professional Services Inc. (PSI) concluded that the coarse aggregate fraction meets the base rock standards of ODOT. The fine aggregate fractions from the boring holes BH 1 and BH 2, and the pit wall samples did not meet ODOT specifications. Applicant’s materials confirm that the older gravel from lower in the ground is of lesser quality, but contend that on the Exhibit 66 expansion site even the lower (deeper) resources meet ODOT standards (). Staff noted concern that the analysis of the overall quality of the aggregate material on the proposed expansion area may be based on too few actual borings and the report relies heavily on the existing pit wall analysis and extrapolation that the material in the existing pit operation is comparable to the expansion site. A review of the applicant’s analysis by Mark H. Reed, Ph.D., Mineral Resource Geologist, Department of Geological Sciences at the University of Oregon, concludes that the samples were not “representative,” and do not provide “adequate information” as required by the state rule. His concerns include the mixing of concrete-grade rock from the shallow layer with poorer quality gravels from the deeper layers, thereby diluting the poorer quality rock with the lesser-in-quantity high grade rock; discrepancies in the BH-3 boring hole log data; and failure to follow best practices for sampling. Dr. Reed provided excerpts from Army Corps of Engineers, ASTM, and AASHTO standards that suggest that samples should allow visual inspection of the discernable strata, and that individual samples from each stratum should be obtained where there is variation between strata in order to assure that the samples are representative of the site’s material. By mixing materials from