South Carolina Grading

Key Concepts

Equipment economics (Construction Planning, Equipment, and Methods, 9th ed., Ch. 2) - Purchase expense is the total delivered (drive-away) cost including all options, shipping and taxes, less the cost of the tires; tires are carried as an operating cost (pp. 72, 88). - Major repairs and overhauls that extend service life are an ownership cost added to basis and depreciated; normal maintenance repairs are an operating cost (pp. 80, 93). - MACRS: cars and light-duty trucks (under 13,000 lb unloaded) are 3-year property; most other construction equipment is 5-year property (p. 78). - Like-kind exchange: unadjusted basis of the new machine = adjusted basis of the traded machine + cash paid; no gain recognized (pp. 75–76). - Rentals are priced daily (8 hr), weekly (40 hr), or monthly (176 hr = 8 hr/day × 22 days) (p. 104). - PCSA repair/maintenance guidelines: 80 to 95% of depreciation for crawler-mounted excavators, 80 to 85% wheel-mounted excavators, 55% crawler cranes, 50% wheel-mounted cranes (p. 97). - Replacement analysis is based on cumulative hours; keeping a machine past minimum total cost applies the hourly difference to every cumulative operating hour (pp. 101–102).

Power requirements (Ch. 6) - Rolling resistance increases about 30 lb/ton per inch of tire penetration (pp. 245–247). - Published crawler drawbar pull assumes a 110 lb/ton haul road (Nebraska tests); pull changes by tractor tons × variation from 110 lb/ton (p. 259). - Altitude: a four-cycle engine loses about 3% per 1,000 ft above sea level; a two-cycle diesel holds full power to 1,000 ft, then loses about 0.9% for each additional 1,000 ft. A 1-in. barometer drop ≈ a 900-ft altitude increase (pp. 265–266).

Earthwork planning (Ch. 3) - Average-end-area volumes are slightly in excess of actual; precision ±1.0%; the trapezoidal end-area formula is about ±0.5% (pp. 127, 130). - For embankments greater than 5 ft in height, most specifications allow organic material to remain if its thickness is only a few inches (p. 131). - Type 1 differing site condition = conditions differ from those "indicated in the contract"; Type 2 = differ from reasonable expectations (p. 121). - Mass diagram: curve above the balance line = haul left to right (up stationing); below = right to left, down stationing (pp. 140–141). - Grid method: single-cell volume = average of the four corner elevation differences × grid area (p. 151).

Key Concepts

Erosion control (SCDOT Section 815) - Inlet filter selection: Type A for peak flow less than 1 ft³/sec, inlet drain area grade less than 5%, and immediate (5-ft radius) grade less than 1%, not for concentrated flow (815.1.1.3.1). Type B for peak flow less than 3 ft³/sec, inlet drain area grade less than 5%, velocity not exceeding 3 ft/sec, where overflow capacity is not required (815.1.1.3.2). Type D for drainage areas up to 2 acres with peak flows greater than 3 ft³/sec and grades greater than 5% (815.1.1.3.3). Type E protects Catch Basin Types 1, 16, 17, 18 after the road surface course is placed (815.1.1.3.4). - Type A filter fabric inlet protection: posts spaced a maximum of 3 feet apart, driven a minimum of 24 inches, fabric to a minimum height of 24 inches above grade (815.4.11.2.2.1). Type B hardware fabric posts: maximum 3 feet apart, driven a minimum of 18 inches (815.4.11.2.3.1). - RECP slope installation: 6-inch deep × 12-inch wide anchor trench; extend the upslope terminal end 30 inches past the trench; staple on 12-inch centers (815.4.2.2.2). Channels: anchor trenches/staple check slots perpendicular to flow across the full channel width at 25-foot intervals, with 6-in × 6-in check slots every 25 feet (815.4.2.2.3). - Sediment tubes: trench depth 20% of tube diameter, do not completely bury, lap adjacent ends a minimum of 6 inches (815.4.5.2). - Silt fence: inspect every 7 days; remove within 30 days after final stabilization or when temporary BMPs are no longer needed (815.4.6). - Temporary flexible pipe slope drains: sized for anticipated flow, in no case less than 8 inches diameter (815.4.12). - BFM: do not exceed 100-ft maximum slope length when gradients are steeper than 4H:1V; general rate 3500 lb/acre (815.4.15.1). Fiber roving: Type A 0.30 lb/SY minimum, Type B 0.15 lb/SY minimum; asphalt 0.25–0.35 gal/SY (815.4.4). - Brush barriers are not measured and not paid directly — incidental to Clearing and Grubbing lump sum (815.5, 815.6).

Key Concepts

Excavation access and egress (Subpart P) - Trench excavations 4 feet (1.22 m) or more in depth must have a stairway, ladder, ramp, or other safe means of egress located so that no more than 25 feet (7.62 m) of lateral travel is required — §1926.651(c)(2). - Structural ramps used solely by employees for access/egress must be designed by a competent person; ramps for equipment access must be designed by a competent person qualified in structural design — §1926.651(c)(1)(i).

Protective systems - Each employee in an excavation must be protected from cave-ins except where the excavation is made entirely in stable rock, or is less than 5 feet (1.52 m) deep and a competent person's examination of the ground gives no indication of a potential cave-in — §1926.652(a)(1). - Deviating from a manufacturer's specifications, recommendations and limitations for a shield or other manufactured system is allowed only after the manufacturer issues specific written approval, which must be in written form at the jobsite — §1926.652(c)(2)(ii). - Type C soil, excavations 20 feet or less deep with vertically sided lower portions: shielded or supported to at least 18 inches above the top of the vertical side, maximum slope 1 1/2:1 above — Appendix B, Figure B–1.3. - Type A soil, more than 8 feet but not more than 12 feet deep with an unsupported vertically sided lower portion: maximum slope 1:1, maximum vertical side 3 1/2 feet — Appendix B, Figure B–1.1.

Soil classification (Appendix A) - Type A requires unconfined compressive strength of 1.5 tsf or greater, but soil that meets that strength and is fissured or subject to vibration is Type B. - A layered system must be classified by its weakest layer; layers may be classified individually only where a more stable layer lies UNDER a less stable layer — Appendix A, paragraph (c)(4).

Other excavation hazards - Flammable gas: ventilation or other adequate precautions to keep exposure not in excess of 20 percent of the lower flammable limit — §1926.651(g)(1)(iii). - Spoil/equipment kept at least 2 feet (.61 m) from the edge, or sufficient retaining devices, or both — §1926.651(j)(2).