Map Surface and Subsurface Water Paths

Draw the site water map

Sketch roof leaders, paved areas, irrigation, slopes, swales, low points and the wall. Add arrows only for flows you can observe.

Document surface flow

Record where water approaches, crosses, ponds near or exits the wall area during weather events. Note dates and conditions.

Treat hidden components as unknown

Do not assume drain rock, filter fabric, pipes or outlets are present or functioning. Ask what investigation and documentation a proposal includes.

Find and verify outlets safely

Record visible outlets and discharge locations without probing, excavating or entering restricted areas. Consider whether discharge could affect neighbours or public space.

Connect erosion to the site record

Photograph scour, sediment, voids, displaced surface material and vegetation changes. A qualified reviewer must interpret their significance.

Define the design boundary

A drainage concept must be coordinated with wall design, soils, site geometry, property boundaries and applicable approvals. Avoid guaranteed-drainage language.

Separate observed and assumed water paths

Build a two-layer drawing: one layer for surface flow, ponding, staining and sediment actually observed, and another for subsurface drains or outlets confirmed by records or qualified investigation. Keep suspected components labelled unknown until evidence resolves them.

• Date rain or irrigation context
• Use different symbols for assumptions
• Show the discharge destination

Ask for a complete water route

A proposal should state how water is intercepted, filtered, conveyed, discharged and managed during overflow, then show how inspection or maintenance access remains possible. Require coordination with wall design, soil conditions, property boundaries and downstream erosion concerns rather than accepting a generic drain detail.

• Trace every inlet to an outlet
• Identify overflow behaviour
• Assign maintenance access

Document construction verification

Before work, list the drainage details that need drawings, product information, photographs, field review or testing. During construction, index evidence by wall segment and elevation so backfilled components can be reconciled with the accepted design instead of disappearing from the project record.

• Photograph layers before concealment
• Label outlets and cleanouts
• Keep substitutions in writing

Create the drainage verification schedule

Before excavation or concealment, list each water-management element that needs drawing confirmation, product data, safe observation, photograph, field review or other accepted evidence. Index collection zones, filter layers, pipes, outlets, overflow paths, surface grading and erosion protection by wall segment. State who reviews substitutions and who confirms discharge locations. The finished schedule should reconcile proposed details with evidence actually collected, while clearly preserving unknown subsurface routes. It is a project record—not proof that drainage is adequate under every storm, irrigation condition or future site change.

• Photograph components before backfill
• Label outlet coordinates and destinations
• Record surface grades after restoration
• Attach approved product substitutions
• Preserve maintenance-access locations