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EXPERT WITNESS OPINION TESTIMONY INTRODUCTION Byron G. Walker, P.E. has been asked to review a (CTL/fHOMPSON, INC. CONSULTING ENGINEERS) letter of February 9, 2001, to Davis Graham & Stubbs LLP, 1550 Seventeenth Street, Suite 500, Denver, Colorado 80202, Attention: Mr. Scot W. Anderson, Subject: Tatum Residence 12630 Highway 12 near Weston, Colorado Job No. 32,485 and provide comments thereto. Byron G. Walker, P.E. is an Environmental Protection Specialist on the staff of the Colorado Division of Minerals and Geology (Division). Other documents reviewed included a (CTL!THOMPSON, INC. CONSULTING ENGINEERS) letter of Mazch 24, 1994, to Pazcel, Mauro, Hultin & Spaanstra, P.C. Suite 3600 1801 Califomia Street Denver, Colorado 80202-2636, Attention Mr. David a. Bailey, Esq. Subject: Consultation Tatum Residence 12630 Highway 12 Near Weston, Colorado Job No. 21,239; an extract of the Journal of the Soil Mechanics and Foundations Division Proceedings of the American Society of Civil Engineers 7278 May, 1970 SM3, Review of Collapsing Soils By John H. Dudley, F. ASCE (1970); the American Society for Testing and Materials D4546-96 Standard Methods for One- Dimensional Swell for Settlement Potential of Cohesive Soils; and Geological Survey Professional Paper 437-A, Alluvial Fans and Near-Surface Subsidence in Western Fresno County California by William B. Bull Studies of Land Subsidence (1964). This review did not include a site visit. No verification of the information provided was accomplished. The review was conducted to determine a degree of confidence, for the Colorado Division of Minerals and Geology (Division), with the opinions presented in the February 9, 2001 letter (page 2), with regard to damage to an adobe structure from "collapse" of supporting foundation soils. FINDINGS OF THE REVIEW The opinions presented by CTL/Thompson, Inc. reference laboratory testing of materials. Bulk dry density was determined, a Harvazd miniature compaction test was performed, and Atterberg limits determined to classify the soil in the Unified Classification system. The CTL/I'hompson report concludes, in part, that the soil in the Tatum crawl space is prone to collapse. The argument is weakened in that the opinion is based on association of soil types and experience in- lieu-ofdhect testing. The conclusion that the soil is prone to collapse has not been well demonstrated by "standard engineering" analyses and procedures directly applicable to the primary (collapse) soil characteristic.