Grading
What to know
Grading questions require fluent contour reading. Know contour interval, index contours, hachures for depressions, and how contours indicate slope direction and steepness. Compute slope as rise divided by run times 100; contour spacing shows intensity. Understand cut and fill, balancing earthwork, topsoil stripping, compaction, and shrink/swell factors. Design drainage with positive flow away from structures, swales, berms, and high and low points. Accessibility limits grades and cross slopes; parking, sports fields, and planting areas have their own grade tolerances.
Traps
Contour lines never cross except at overhangs; closely spaced contours mean steep slopes. A depression is shown with hachures, not a summit. Cut-and-fill calculations often hide topsoil or shrinkage adjustments. Do not assume a flat pad is best-positive drainage needs slope. Retaining walls shift loads and require drainage; do not place them without an outlet. Accessible routes cannot rely on a 5% slope everywhere; running slope and cross slope are separate checks. Verify whether existing contours are dashed or solid.
Worked example
Balance cut and fill: 10,000 sf cut area × 2 ft average depth = 20,000 cf cut. A 20,000 sf fill area × 1 ft average depth = 20,000 cf fill. The earthwork balances before topsoil and compaction adjustments. Rule of thumb: strip and stockpile topsoil before mass grading, then respread it.
Drainage
What to know
Drainage combines hydrology, hydraulics, and stormwater management. Know the rational method Q = CiA, runoff coefficients, time of concentration, curve numbers, and design storm frequencies. Distinguish pre- from post-development peak flows and the need for detention or retention. Green infrastructure-bioretention, swales, permeable pavement, green roofs, cisterns, and infiltration-manages volume and quality. Understand hydrologic soil groups, infiltration testing, underdrains, overflow paths, freeboard, and outlet protection. Erosion and sediment control (silt fence, check dams, sediment basins) and NPDES/MS4 requirements are commonly tested.
Traps
Detention holds water temporarily; retention holds it permanently. Overflow must be designed for the larger storm, not just the water-quality volume. Compaction during construction can destroy infiltration rates; protect basins from sediment. Do not assume flat sites drain-grade to an outlet. Offsite drainage cannot be ignored, and floodplain compensatory storage may be required. The rational method is for small, uniform catchments; do not apply it blindly to large watersheds.
Worked example
Q = CiA. C = 0.30, i = 4 in/hr, A = 2 acres. Q = 0.30 × 4 × 2 = 2.4 cfs. Rule of thumb: 1 acre-inch per hour equals about 1.008 cfs, so units are consistent. Check whether the design storm is 2-year, 10-year, or 100-year before sizing a storm pipe.
Construction Documentation
What to know
Construction documentation communicates design through drawings and specifications. Drawings are organized by discipline and sheet series (general, civil, landscape), with plans, elevations, sections, details, schedules, and legends. Specifications follow MasterFormat divisions; Division 01 covers general requirements, and sitework falls in Divisions 31–33. Know prescriptive versus performance specifications, addenda, submittals, shop drawings, samples, mockups, record drawings, and operation and maintenance manuals. Bidding documents include the invitation, instructions, bid form, general and supplementary conditions, and technical specifications.
Traps
Dimensions govern over scaled measurements. Drawings and specifications are complementary; one does not automatically override the other unless the contract states a precedence. Submittal review is not a redesign opportunity. Record drawings reflect what the contractor reports; as-builts may be contractor-prepared. Delegated design-retaining walls, structural connections-must be clearly assigned. A planting plan must reconcile with the plant schedule. Addenda are issued before bid opening; bulletins or supplemental instructions come after award.
Worked example
A planting plan shows 12 shade trees; the schedule lists 14. The written schedule typically governs quantity, but resolve the conflict with an RFI before bidding. Rule of thumb: dimension, do not scale; specify, do not assume.