Langan Rebuttal Report 9 15 2025

ROCK MASS RATING (RMR) - LOWER RANGE A. CLASSIFICATION PARAMETERS AND THEIR RATINGS Parameter 1 Strength of intact rock material Point-load strength index Uniaxial comp. strength Rating Range of Values > 1,450 psi 580 psi - 1,450 psi 290 psi - 580 psi 145 psi - 290 psi > 36,300 psi 14,500 psi - 36,300 psi 7,250 psi - 14,500 psi 3,630 psi - 7,250 psi 15 12 7 4 For this low range - Uniaxial Compressive Strength Test is preferred 725 psi 145 psi < 145 psi 3,630 psi 725 psi 2 1 0 2 2 Drill Core Quality RQD 90% - 100% 75% - 90% 50% - 75% 25% - 50% < 25% Rating 20 17 13 8 3 7.87 in - 23.6 in 10 2.36 in - 7.87 in 8 < 2.36 in 5 3 3 Spacing of Joints (See E) Rating > 78.7 in 20 Condition of discontinuities Very rough surfaces Not continuous No separation Unweathered wall rock Rating 30 23.6 in - 78.7 in 15 8 4 Slightly rough surfaces Slightly rough surfaces Separation <0.04 in Separation <0.04 in Slightly weathered walls Highly weathered walls Sickensided surfaces Soft gouge >0.2 in thick or Gouge <0.2 in thick or Separation >0.04 in or Separation 0.04-0.2 in Continuous Continuous 20 10 3 < 10 10 - 25 25 - 125 > 125 0 < 0.1 0.1 - 0.2 0.2 - 0.5 > 0.5 Completely dry 15 Damp 10 Wet 7 Dripping 4 Flowing 0 Unfavourable -10 -15 -50 Very Unfavourable -12 -25 -60 25 25 Inflow per 32.8 ft tunnel length (L/min) 5 Groundwater (Joint water press)/ (Major principal σ) General Conditions Rating None 10 Rating Value for Part A: 48 B. RATING ADJUSTMENTS FOR DISCONTINUITY ORIENTATIONS (See E & F) Strike and dip orientations Tunnel & mines Ratings Foundations Slopes ENTER RATING NUMBERS TO THE RIGHT SEPARATELY Very favourable 0 0 0 Favourable -2 -2 -5 Fair -5 -7 -25 Tunnel & mines Foundations Slopes ENTER RATING HERE ENTER RATING HERE -5 Rating Value for Part B: -5 C. ROCK MASS CLASSES DETERMINED FROM TOTAL RATINGS ("number of points") Rating 100 <-- 81 80 <-- 61 60 <-- 41 40 <-- 21 Class I II III IV < 21 V Very good rock Good rock Fair rock Poor rock Very poor rock Description CLASS III; Fair Rock D. MEANING OF ROCK CLASSES Class number Average stand-up line Cohesion of rock mass (psi) Friction angle of rock mass (deg) I II III IV V 20 yrs for 49.2 ft span > 58 psi 1 year for 32.8 ft span 43.5 psi - 58 psi 1 week for 16.4 ft span 29 psi - 43.5 psi 10 hrs for 8.2 ft span 14.5 psi

ion angle of rock mass (deg) I II III IV V 20 yrs for 49.2 ft span > 58 psi 1 year for 32.8 ft span 43.5 psi - 58 psi 1 week for 16.4 ft span 29 psi - 43.5 psi 10 hrs for 8.2 ft span 14.5 psi - 29 psi 30 min for 3.28 ft span < 14.5 psi > 45˚ 35˚ - 45˚ 25˚ - 35˚ 15˚ - 25˚ < 15˚ 9.84 ft - 32.8 ft 2 0.004 in - 0.04 in 4 Slightly rough 3 Hard filling > 0.2 in 2 Moderately weathered 3 32.8 ft - 65.6 ft 1 0.04 in - 0.2 in 1 Smooth 1 Soft filling < 0.2 in 2 Highly weathered 1 > 65.6 ft 0 > 0.2 in 0 Sickensided 0 Soft filling > 0.2 in 0 Decomposed 0 Strike parallel to tunnel axis Dip 45 - 90˚ Very unfavourable Dip 0-20 - Irrespective of strike˚ Dip 20 - 45˚ Fair E. GUIDELINES FOR CLASSIFICATION OF DISCONTINUITY CONDITIONS Discontinuity length (persistence) Rating Separation (aperture) Rating Roughness Rating Infilling (gouge) Rating Weathering Rating < 3.28 ft 6 None 6 Very rough 6 None 6 Unweathered 6 3.28 ft - 9.84 ft 4 < 0.004 in 5 Rough 5 Hard filling < 0.2 in 4 Slightly weathered 5 F. EFFECT OF DISCONTINUITY STRIKE AND DIP ORIENTATION IN TUNNELING** Strike perpendicular to tunnel axis Drive with dip - Dip 45 - 90˚ Drive with dip - Dip 20 - 45˚ Very favourable Favourable Drive against dip - Dip 45 - 90˚ Drive against dip - Dip 20 - 45˚ Fair Unfavourable Fair * Some conditions are mutually exclusive. For example, if infilling is present, the roughness of the surface will be overshadowed by the influence of the gouge. In such cases use A.4 directly. ** Modified after Wickham et al (1972).