🔎 Plan Symbols

• Sanitary sewer: dashed line with arrows; manholes “MH”, invert/rim called out.
• Storm drain: dashed/alternate line; catch basins “CB”, area drains “AD”.
• Water main/service: continuous line; valves “GV/AV”, fire hydrants “FH”.
• Gas: dashed line with “GAS” tags and valves.
• Power/telecom: duct bank/handholes “HH”, pull boxes “PB”.
• Crossings: callout bubbles with depth, sleeve, separation notes.
• Profiles: show pipe invert, slope, structures, depth below grade.

📐 Key Calculations

• Slope (%): rise ÷ run × 100. Example: 1% = 0.12″/ft.
• Invert drop: Δelev = slope × run. (Feet) → drop(in) = slope% × run(ft) × 0.12.
• Trench volume (CY): width(ft) × depth(ft) × length(ft) ÷ 27.
• Pipe count: total length ÷ stick length (PVC/C900/HDPE often 20′; DI 18–20′).
• Bedding volume (CY): trench width × bedding depth × length ÷ 27 (add ~10% waste).
• Structure excavation: (OD length × OD width × depth) ÷ 27 for MH/CB pits.

📏 Minimum Slopes & Clearances (Typical — verify project specs)

• San sewer: 2% for 2–3″ laterals; 1% for 4″; 0.5–0.8% for 6–8″ mains (check local code).
• Storm: 0.5–1.0% typical (larger pipes may run flatter with design calcs).
• Water: no slope req.; maintain cover (e.g., 36″+ frost-dependent).
• Separations (horiz.): water to sewer 10′ min (typ.); crossings: 12–18″ vertical with sleeve per AHJ.
• Utility corridors: keep gas & electric separated from water/sewer per plan notes.

🧱 Materials, Bedding & Backfill

• Pipe (san/storm): PVC SDR-35, HDPE corrugated, RCP (reinforced concrete) per loads.
• Water main: PVC C900/C909, DIP, HDPE (fused).
• Gas: PE (yellow), tracer wire required.
• Power/Telecom: PVC schedule/duct bank, spare conduits as noted.
• Bedding: ¾″ minus or sand; typical 4–6″ below + to springline.
• Initial backfill: to 12″ above crown; hand-compact around pipe.
• Compaction: 90–95% (Std./Mod. Proctor) per spec; lifts 6–12″.
• Warning tape: detectable tape 12–18″ above utility; tracer wire on non-metallic.

⚡ Estimating Shortcuts

• Fittings count: add 1 fitting per 80–120′ + all tees/offsets shown on plan.
• Manholes & CBs: count from plan; add riser rings from profile rim/invert data.
• Cleanouts: at property line & per code spacing on laterals (e.g., 100′ typ.).
• Rock/over-excavation: carry allowance if geotech indicates rock/high groundwater.
• Traffic control & dewatering: include if trench near ROW or below water table.

🦺 Safety & Field Notes

• 811 utility locate before digging; verify all marks and depths.
• Trench safety: sloping/shoring/boxing required per soil type & depth.
• Confined space: MH/CB entries require permit & gas monitoring.
• Bypass & flow control: plan for temporary pumping on live lines.
• Testing: pressure/leak tests (water/gas), mandrel/CCTV for sewer, vacuum tests on MHs.

📝 Self Test

1. A 6″ sewer main runs 240′ at 0.5% slope. What is the total invert drop?
2. You’re installing 8″ C900 water main at 400′. How many 20′ sticks do you need (no waste)?
3. Trench is 2.5′ wide × 5′ deep × 300′ long. Approximate excavation in CY?
4. How much bedding (6″ deep) is required for that trench in CY (add 10% waste)?
5. Minimum typical horizontal separation between water and sewer?

Answers: (1) 0.5% × 240′ = 1.2′ drop (≈14.4″). (2) 400′ ÷ 20′ = 20 sticks. (3) 2.5×5×300 ÷ 27 ≈ 139 CY. (4) Bedding vol = 2.5×0.5×300 ÷ 27 ≈ 14 CY; +10% ≈ 15.4 CY. (5) ~10′ (verify AHJ).