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Civil Sheets: The C Series

Civil Sheets: The C Series

Welcome

Hello, and welcome. This is Super Structures General Contractors — a national general contractor headquartered in Powhatan, Virginia — here to help you and your clients build something that lasts. We're glad you're with us, and we look forward to connecting with you.

Alright, Civil Sheets: The C Series. Don't let the plain title fool you. Here's the part that actually matters on the job: Civil sheets set the building where it sits and how high it sits, so every grade, pipe invert, and finished floor on the job traces back to the C series and the benchmark it names. Learn it well and you'll never pour a slab that ends up lower than the parking lot.

The C sheets are drawn by the civil engineer, usually in decimal feet on a survey datum, and they are the only sheets that tie the building to the real ground. On our apartment set the C series runs from existing conditions through site details. Here is how to read each one.

Existing conditions and the survey

C-100 is the boundary and topographic survey. Read it for: the property lines with bearings and distances; easements (utility, drainage, access) that you cannot build in or stockpile on; the benchmark description and elevation and the datum it sits on (NAVD88 or assumed); existing contours (dashed); existing utilities with sizes and a note on how they were located; trees to be saved; adjacent buildings and street elevations.

What to check: the benchmark must physically exist and be recoverable — a nail in a pole, a chiseled square on a curb, a monument. Confirm the same datum on every C sheet and that the survey is recent. Everything you set vertically starts here.

Demolition and the site plan

The demolition plan (C-150) hatches pavement to be removed, marks structures and utilities to be removed or abandoned, and shows what to protect in place. The site plan or layout plan (C-200) is the sheet you will lay the building out from: the building footprint with corner coordinates (northings and eastings) or dimension ties to the property lines, setbacks and the zoning table, parking stalls and counts, curb lines and radii, sidewalks, the accessible route from the accessible stalls to the entrance, the dumpster pad, retaining walls, fences, and site lighting bases.

What to check: the footprint dimensions against the overall dimensions on A-101, and the basis — civil may draw to face of building while structural draws to face of foundation. Settle which corner is the building corner before the surveyor stakes anything.

Grading and drainage with spot elevations and contours

C-300 shows proposed contours solid over existing dashed, and spot elevations everywhere a contour is not precise enough. Learn the tags: TC and BC (top and bottom of curb), FG (finished grade), TW and BW (top and bottom of wall), ME (match existing), HP and LP (high and low point), and FFE (finished floor elevation, here 412.50). Slope arrows with percentages show which way water goes. Storm structures carry rim and invert elevations; pipes carry size, length, and slope.

Reading between contours is interpolation: a point halfway between 411 and 412 is about 411.50. What to check at every exterior door: the grade outside must sit below the floor and slope away; the accessible route must hold 5 percent running and 2 percent cross slope or less; the garage apron must drop away from the door. A spot elevation 2 inches above the FFE at a door is a flooded unit.

The utility plan

C-400 draws each utility by line type: water (W), sanitary (SS), storm (ST), gas, and the electric and communications conduits that may be by the utility. For each pipe you get size, material (DIP, PVC SDR 35, HDPE), inverts at every structure, slope, and cover. Find the building connection points: the domestic water and the fire line with its backflow, PIV, and FDC; the sanitary exit with its invert 5 feet outside the building; roof drain leaders tying to storm.

What to check: the sanitary invert at the building face against the invert the plumbing underslab plan assumes — if civil is 2 feet lower than plumbing expects, the building drain cannot reach it at the required slope. Also check crossings (storm over sanitary, water over sewer with the required separation) and cover depth under paving.

Erosion control, SWPPP, and site details

C-500 is erosion and sediment control: silt fence, inlet protection, the stabilized construction entrance, concrete washout, stockpile locations, and the stabilization sequence by phase. Local stormwater rules apply to private work, and the inspector will walk this sheet. C-600 holds the site details: pavement sections (base thickness, asphalt lifts), curb sections, sidewalk and ramp details with detectable warnings, pipe bedding, structure details, and retaining wall sections.

What to check: the pavement section against the geotechnical report, and the detail numbers called out on C-200 and C-300 against what is actually on C-600.

Tying civil elevations to finished floor

The whole set meets at one line: civil says FFE 412.50; architectural says Level 1 is 100'-0" and a general note says 100'-0" equals 412.50; structural says top of slab 100'-0". That conversion note is the hinge. Civil works in decimal feet: 0.50 feet is 6 inches, 0.10 feet is 1.2 inches, 0.01 feet is about 1/8 inch. Architectural and structural work in feet and inches. Translate carefully — a top of footing at 96'-0" is 4 feet below the floor, so its civil elevation is 408.50.

Use the civil benchmark to set your own job benchmark near the building, then prove the FFE by checking door thresholds, aprons, and the accessible route against the grading plan before the slab forms go in.

Going Deeper (Intermediate)

Civil plans and profiles (C-401) show each utility run in section: the pipe, its slope, the ground above it, and every crossing. A profile tells you how deep the trench is and where the storm pipe passes near a footing. A footing's influence zone runs down and out at roughly 1 to 1 from its bottom edge; a trench inside that zone needs an engineered answer before you dig.

Advanced / Pro-Level

Pros order the surveyor's stakeout from the civil coordinates and verify it against the A and S overall dimensions and diagonals before anyone trusts a hub. They read the detention pond and outlet structure elevations, because a pond that must be built before paving sets the sequence for the whole site, and they check retaining wall TW and BW elevations against the architectural grade at the building and site lighting bases against the electrical site plan, because the civil plan shows the pole and the E sheet shows the conduit.

Practice Challenge

The civil FFE is 412.50. The architectural general note says Level 1 at 100'-0" equals 412.25. The structural notes say top of slab 100'-0" with no civil conversion. What do you do before the footings go in? (Answer: stop and write the RFI to the civil engineer and the architect; do not pick one. A 3-inch disagreement changes every door threshold, apron slope, accessible route, and the sanitary invert. Get a single written conversion, have it posted to all three disciplines, and set your job benchmark from that number only.)

In Practice

A super who checks the sanitary invert at the building wall against the plumbing underslab plan in the first week finds the 18-inch problem on paper. A super who finds it when the plumber's laser hits the civil pipe pays for a lift station.

Common Mistakes to Avoid

Takeaway: Civil sheets set the building where it sits and how high it sits, so every grade, pipe invert, and finished floor on the job traces back to the C series and the benchmark it names.

Educational content — not legal, safety, or contractual advice. Follow your company's procedures, your contract, and the OSHA and local requirements that apply to your site.

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