J_2024 05 09_West Orange Stormwater Management Plan

ENGINEERING ROCK CLASSIFICATION AND CORE DESCRIPTION CHART (1) DESCRIPTIVE TERMINOLOGY FOR JOINT SPACING Description Term Spacing of Joints Very Close Close Moderately Close Wide Very Wide Less than 2 inches 2 inches to 1 foot 1 foot to 3 feet 3 feet to 10 feet Greater than 10 feet RELATIONSHIP OF RQD AND ROCK QUALITY Rock Quality Designation (RQD) (2) Description of Rock Quality 0 – 25% 25 – 50% 50 – 75% 75 – 90% 90 – 100% Very Poor Poor Fair Good Excellent (1) Core description system is based on a suggested system proposed in the ASCE Rock Mechanics Seminar in April and May of 1968 entitled “Geologic Considerations of Rock Mechanics” as presented by Don V. Deere. (2) “Rock Quality Designation” is defined as a modified core recovery ratio which considers only pieces of core that are at least 4 inches long. Obvious features induced by drilling are ignored in this system. MELICK-TULLY AND ASSOCIATES, a Division of GZA PLATE 7