Drainage and dewatering — when the course needs to handle rain
Soil, drainage patterns, preliminary investigations and rainwater as a resource
After any modification, extension, or removal of parts.
§The soil determines
Water moves quickly through sandy soil and slowly through clay soil. Therefore any drainage task starts by knowing the soil: dig a soil profile, look at the layers, and assess where the water actually builds up. In clay soil the drainage lines must be closer together than in sandy soil because the water can only move a short distance to the pipe. The school subject on drainage requires exactly that you can calculate the distance between the drainage pipes based on the soil conditions present.
§Drain patterns and fall
The classic patterns are herringbone where side strings run at a sharp angle into a main string and grid pattern where strings run parallel with a collection line at the end. The pipes are laid with even fall toward outlet or well surrounded by filter gravel so they do not clog. Wells along the way make the system inspectable and flushable. In a USGA-built green the drain strings at the bottom are recommended laid with at most about 4.5 metres (15 feet) between them — a good picture of how closely drain should lie when the requirement for drainage is high.
§Preliminary investigations — before the shovel hits the ground
- 01Soil: profiles or boreholes so drainage distance and depth can be determined.
- 02Spot heights and gradients: surveying the terrain so water actually flows toward the outlet.
- 03Existing conduits: obtain conduit information in the LER register — it is mandatory to inquire before digging.
- 04Existing drains: old drain maps and observations of wet stripes save expensive surprises.
- 05Drainage: clarify where the water may be conducted — discharge may require a permit from the municipality.
§Drainage on the surface
Drain underground is only half the solution — the surface must also direct water correctly. Fall and shaping on greens, tees and fairways controls where water collects, and depressions without outlets become the classic puddles that suffocate grass and invite moss and algae. The toolkit includes everything from top dressing and levelling of hollows through trenches and slot drains to actual basins that collect water.
| PLACEHOLDER_38 | Used when |
|---|---|
| Pipe drain (herringbone/grille) | The area is generally water-bearing and the soil conducts poorly |
| Slot drain/stub drain | Local wet strips and waterlogged areas should be connected to existing drainage |
| Fascine. | Smaller water quantities should be infiltrated locally |
| Pool/lake | Large amounts of water must be delayed and possibly reused for watering |
| Terrain regulation | Surface water must be directed away from joints and low spots |
§Rainwater as a resource
Modern courses think drainage and watering together: The water that causes problems in winter is a resource in summer. The competence objectives require knowledge of sustainable drainage solutions and collection, drainage and reuse of water — in practice basins and lakes that act as buffers during heavy rain and as water reserves during drought, preferably monitored by sensors. This way, climate adaptation and sustainable management become two sides of the same drainage project.
“Water always finds a way — the question is whether it is your way or its own.”
— Drainage principle