△
Safety Cue
Task-specific safety guidance for ordinary trenching and drainage hazards.
Chapter 16 · LS-091 – LS-096
Install Landscape Drainage for a Wet Area
Identify water-collection points, lay out a drainage path, install a gravel trench and perforated pipe where appropriate, route discharge safely to a lawful outlet, and inspect the finished system for capture, flow, and overflow protection.
Field Cue System
These cues appear at the point of work. They identify safety, code, manufacturer, and measurement issues before they become a blocked outlet, undermined structure, or unlawful discharge.
✋
Critical Safety Cue
Serious injury, utility strike, structural undermining, or unlawful discharge is possible.
⛑
Field Safety Cue
Practical work-area safety: trench footing, wet soil, weather, and site hazards.
▤
Code Alert
Local requirements vary. Verify discharge point, easement, and jurisdictional rules.
▧
Manufacturer Cue
Follow product-specific instructions for pipe, fittings, fabric, and inlet components.
▱
Measurement Cue
Invert elevation, slope, and fall-verification guidance.
Job Overview
This chapter qualifies you to install one approved landscape-drainage trench or collection system for a wet residential area. The finished work product is a supported, accessible drainage system that captures water at the identified collection point, carries it along a continuous fall to a lawful outlet, protects that outlet from erosion and blockage, provides an emergency overflow route, and passes a controlled flow test.
You will confirm the wet-area cause is suitable for a landscape drain, verify property and discharge requirements, locate utilities, lay out the drainage path and invert elevations, excavate a stable trench, install separation fabric and aggregate, install pipe and fittings at the correct slope, connect to the lawful outlet, protect that outlet, establish an overflow path, backfill without creating settlement, and inspect and test the finished system.
This project depends directly on the Chapter 1 readiness inspection and the drainage findings recorded there. It follows the System-Sequence Control rule in the book outline: positive drainage is established before edging, fabric, mulch, planting, turf, or irrigation conceal grading defects, and any below-grade drainage work required by the design is installed before final mulch or turf.
Skills You Will Demonstrate
- LS-091 — Identify water-collection points from the drainage plan and site observation.
- LS-092 — Lay out the drainage path, including invert elevations and required fall.
- LS-093 — Install a gravel trench with separation fabric and a stable trench bottom.
- LS-094 — Install perforated drain pipe where appropriate, with correct orientation and fittings.
- LS-095 — Route discharge safely to a lawful outlet with erosion protection and overflow provision.
- LS-096 — Inspect drainage performance through a controlled flow test and documented findings.
Where This Skill Fits
This chapter uses the wet-area finding recorded in the Chapter 1 Landscape Readiness Worksheet and the grading work performed in Chapter 5. It applies before Chapter 7 fabric and mulch conceal grade, before Chapter 8 through Chapter 10 planting occupies the bed, and before Chapter 11 through Chapter 13 turf work is placed over the drained area. The completed drainage record from this chapter feeds directly into Chapter 19 restoration, where drainage function is reverified, and into the Chapter 20 capstone, where drainage installed under this chapter's method may be part of the final integrated project.
A landscape drain installed under this chapter is not a substitute for a plumbing, foundation, sewer, or structural repair. Where the wet-area cause is one of those conditions, this chapter requires referral rather than installation.
Scope and Intended Use
This chapter covers:
- confirming that a landscape drain is the correct response to the identified wet-area cause
- verifying property, easement, and lawful-discharge requirements before excavation
- locating utilities before trenching
- laying out the inlet, trench, pipe, outlet, and overflow route with invert elevations and required fall
- excavating a stable trench without undermining structures, hardscape, roots, or utilities
- installing separation fabric, gravel bedding, perforated or solid pipe, fittings, and cleanouts
- connecting to a lawful outlet and protecting that outlet from erosion, pests, blockage, and freezing
- establishing an emergency overflow route
- backfilling and restoring grade without creating settlement
- performing a controlled flow test and inspecting collection, pipe flow, leaks, ponding, outlet, erosion, and overflow
This chapter does not authorize the learner to:
- excavate before utility locating is complete and confirmed
- install a landscape drain where the wet-area cause is a plumbing, foundation, sewer, or structural defect; refer these conditions to the required qualified professional
- discharge water toward foundations, entrances, neighboring property, sidewalks, roads, public hazards, or any prohibited discharge point
- connect a landscape drain to a sanitary sewer, septic system, or any cross-connection with potable water
- conceal an unresolved drainage failure with mulch, soil, or turf rather than correcting it
Any wet area that is not suitable for a landscape drain, or any discharge point that is not confirmed lawful, must be referred to the required qualified professional and resolved before this chapter's work proceeds.
Reference Conventions
Establish these references before excavation begins, and do not change them mid-installation.
| Term | Definition |
|---|---|
| Inlet | The point where surface or subsurface water enters the drainage system, as identified on the approved drainage plan |
| Invert elevation | The elevation of the interior bottom of the pipe at a given point along its length, used to verify continuous fall |
| Fall | The continuous downward slope of the pipe and trench bottom from inlet to outlet, stated by the approved drainage plan |
| Lawful outlet | The discharge point confirmed by the approved drainage plan and applicable local requirements as an acceptable destination for the collected water |
| Overflow route | The path collected water follows if the drainage system's capacity is exceeded, verified not to direct water toward foundations, entrances, or prohibited discharge points |
| Cleanout | An accessible fitting installed in the pipe run to allow inspection and clearing of blockages |
Project and Reference Record
Before beginning excavation, record the project identification directly on the Drainage Installation Record:
Property address: ______________________ Wet-area location: ______________________
Date started: ____________ Installer name: ____________ Approved drainage plan reference: ______________________
Prerequisites
- An approved landscape-drainage plan identifying the water source, collection point, soil, slope, pipe, aggregate, fabric, outlet, cleanout, and overflow
- A completed Chapter 1 Landscape Readiness Worksheet showing the wet-area finding and any related drainage deficiency
- Confirmed property, easement, and discharge requirements for the intended outlet
- Confirmed availability of the utility-locating service used for Step 4 of this chapter
- Identification of whether the wet-area cause requires a plumbing, foundation, sewer, or structural professional instead of a landscape drain
Common Field Fundamentals
Every landscape drain in this chapter depends on four fundamentals: a correctly diagnosed wet-area cause, a verified continuous fall from inlet to outlet, a lawful and protected outlet, and a documented flow test confirming the system performs as installed.
Cause ConfirmationWet area verified as suitable for a landscape drain rather than a plumbing or structural repair
Utilities and BoundariesLocating complete and property, easement, and discharge requirements verified before excavation
Trench and PipeStable trench bottom, separation fabric, gravel bed, and pipe installed at continuous fall
Outlet and OverflowLawful discharge point protected from erosion, pests, blockage, and freezing, with an emergency overflow route
Backfill and GradeTrench backfilled and grade restored without creating settlement
Flow TestControlled flow test performed and collection, pipe flow, leaks, ponding, outlet, erosion, and overflow inspected
Diagnosis, Utilities, and Stop-Work Conditions
Confirm the wet-area cause is suitable for a landscape drain rather than a plumbing, foundation, sewer, or structural repair before any excavation begins. Verify property, easement, and discharge requirements for the intended outlet. Locate utilities before marking the trench path. Do not excavate, install pipe, or connect to an outlet until these three conditions are confirmed.
LS-091 – LS-096
Drainage Installation / Site Utility Qualification
Landscape Drainage System for a Wet Area
A. Finished Project Specification
Deliverable: one installed landscape-drainage trench or collection system serving the identified wet area, with a stable trench, correctly oriented pipe on continuous fall, protected connections, a lawful and protected outlet, a functioning emergency overflow route, and a passed controlled flow test.
B. Component Schedule
| Component | Quantity | Material | Finished Size | Preparation |
|---|---|---|---|---|
| Trench | Per approved drainage plan length | Native soil, excavated | Width and depth per approved plan | Stable bottom, continuous fall verified before pipe installation |
| Separation fabric | Per approved plan, if specified | Per manufacturer product identified in the plan | Cut to trench dimensions with specified overlap | Fitted to trench without gaps at seams |
| Drainage aggregate | Per approved plan quantity | Per approved plan gradation | Bedding depth and surround depth per plan | Placed in specified lifts around pipe |
| Drainage pipe | Per approved plan length | Per approved plan material and diameter | Cut square to required run lengths | Perforation orientation per plan; ends deburred |
| Fittings and cleanouts | Per approved plan schedule | Compatible with specified pipe | Per approved plan locations | Fully seated and accessible for maintenance |
| Inlet basin or grate | Per approved plan, if specified | Per manufacturer product identified in the plan | Per approved plan location and elevation | Set level and connected to the pipe run |
C. Record and Reference Takeoff
- Plans and records: approved drainage plan, water source and collection-point data, soil information, slope requirements, pipe and aggregate specifications, fabric product data, outlet and cleanout locations, and overflow route.
- Utility locating: confirmed request submitted to the required utility-location service, with markings verified present before excavation.
- Property and discharge verification: confirmed property, easement, and lawful-discharge requirements for the intended outlet.
- Photographic and elevation record: photographs and invert-elevation readings at the inlet, each fitting, and the outlet before backfill.
D. Acceptance Standards
| Check | Standard |
|---|---|
| Cause suitability | Wet-area cause confirmed suitable for a landscape drain; plumbing, foundation, sewer, or structural causes referred rather than drained |
| Utility and boundary verification | Utility locating confirmed and property, easement, and discharge requirements verified before excavation |
| Continuous fall | Invert elevation decreases continuously from inlet to outlet with no flat or reverse-sloped section |
| Trench and pipe condition | Stable trench bottom, correctly placed fabric and aggregate, and pipe installed in the specified orientation with fully seated fittings |
| Outlet condition | Discharge point confirmed lawful and protected from erosion, pests, blockage, and freezing |
| Overflow route | Emergency overflow route established and verified not to direct water toward foundations, entrances, or prohibited discharge points |
| Flow test | Controlled flow test passed with no leaks, no unexpected ponding, and confirmed discharge at the outlet |
E. Preparation — Diagnosis, Verification, and Layout
- Review the drainage plan, water source, collection point, soil, slope, pipe, aggregate, fabric, outlet, cleanout, and overflow. Confirm the plan is current and matches the wet-area condition observed on site.
- Confirm the wet-area cause is suitable for a landscape drain rather than a plumbing, foundation, sewer, or structural repair. Refer any condition outside this scope to the required qualified professional before continuing.
- Verify property, easement, and discharge requirements. Confirm the intended outlet is an approved discharge point.
- Locate utilities. Do not mark the trench path with stakes driven below the surface, or begin excavation, until utility locating is complete and confirmed valid.
- Mark the inlet, trench, pipe, outlet, and overflow route. Use stakes and a string line to define the full path before digging.
- Establish invert elevations and required fall. Record the target elevation at the inlet, at each fitting location, and at the outlet using the line level or laser level.
F. Excavation and Trench Preparation
- Excavate the trench without undermining structures, hardscape, roots, or utilities. Keep excavated soil and materials clear of the trench edge.
- Shape a stable trench bottom. Remove soft spots, organic pockets, and loose debris that would allow settlement under the pipe.
- Install separation fabric where specified. Fit the fabric to the trench dimensions with the overlap stated in the approved plan.
- Place the initial gravel bed. Spread the bedding layer to the depth specified in the approved plan before setting pipe.
G. Pipe, Fittings, and Aggregate
- Install perforated or solid pipe in the specified orientation. Confirm perforation-down or perforation-up orientation matches the approved plan before backfilling any section.
- Connect fittings and cleanouts. Seat each fitting fully and position cleanouts for future access.
- Maintain continuous slope. Recheck invert elevation at each fitting against the Step 6 targets before proceeding to the next section.
- Place drainage aggregate around and above pipe. Place aggregate in the lifts specified in the approved plan without displacing the pipe.
- Fold or terminate fabric according to the design. Close the fabric over the aggregate as specified to maintain separation from backfill soil.
- Install inlet basin, surface grate, or collection stone where specified. Set the component level and connected to the pipe run at the approved elevation.
H. Outlet, Overflow, and Backfill
- Connect to the lawful outlet. Complete the final connection only after the outlet has been confirmed under Step 3.
- Protect the outlet from erosion, pests, blockage, and freezing. Install the erosion protection, screen, or other component specified in the approved plan.
- Establish emergency overflow. Confirm the overflow route directs excess water away from foundations, entrances, neighboring property, and any prohibited discharge point.
- Backfill and restore grade without creating settlement. Backfill in lifts, firming lightly, and match the surrounding grade.
I. Testing and Inspection
- Perform a controlled flow test. Introduce water at the inlet using the method specified in the approved plan and observe flow through the full system to the outlet.
- Inspect collection, pipe flow, leaks, ponding, outlet, erosion, and overflow. Confirm water enters at the inlet, flows continuously to the outlet, and discharges without leaks, unexpected ponding, or erosion.
- Document route, elevations, outlet, and test. Record the trench path, invert elevations, outlet location and condition, and flow-test results on the Drainage Installation Record.
Common Inspection Review
Review every completed drainage installation using the same checks regardless of trench length or wet-area cause.
- Cause check: confirm the wet-area cause was verified suitable for a landscape drain before excavation began.
- Utility and boundary check: confirm utility locating and discharge verification were completed before excavation.
- Fall check: confirm invert elevation decreases continuously from inlet to outlet with no flat or reverse-sloped section.
- Outlet check: confirm the outlet is lawful, connected, and protected from erosion, pests, blockage, and freezing.
- Overflow check: confirm the emergency overflow route does not direct water toward a prohibited point.
- Flow-test check: confirm the controlled flow test passed with no leaks and no unexpected ponding.
Complete the Inspection Checklist in the section below before proceeding to Chapter 17.
Image Placeholder
Image Placeholder
Image Placeholder
Image Placeholder
Image Placeholder
Image Placeholder
Failure Points and Troubleshooting
Cleanup
This chapter ends with a tested, documented drainage system, not an unverified trench closed and left for later chapters to discover problems in.
- Remove excess excavated soil, unused aggregate, pipe offcuts, and fabric scraps from the work area
- Return borrowed plans and utility records to their source or designated storage
- Rinse and store trenching tools, the pipe cutter, and the level equipment used for this installation
- Organize invert-elevation records and flow-test photographs by section to match the Drainage Installation Record
- Confirm the cleanout locations remain accessible and are not buried beyond the approved access depth
Field Terms
- Inlet
- The point where surface or subsurface water enters the drainage system.
- Invert Elevation
- The elevation of the interior bottom of the pipe at a given point along its length.
- Fall
- The continuous downward slope of the pipe and trench bottom from inlet to outlet.
- Lawful Outlet
- The confirmed, approved discharge point for the collected water.
- Overflow Route
- The path collected water follows if the drainage system's capacity is exceeded.
- Cleanout
- An accessible fitting installed to allow inspection and clearing of blockages.
- Separation Fabric
- Fabric placed between soil and drainage aggregate to preserve aggregate porosity.
- Controlled Flow Test
- A test introducing a known volume of water at the inlet to verify continuous flow, leak-free connections, and lawful discharge.
Skill Check
- What conditions require a wet area to be referred to a plumbing, foundation, sewer, or structural professional instead of being fitted with a landscape drain?
- Why must invert elevation be checked at each fitting rather than only at the inlet and outlet?
- What must be verified about an outlet before it may be connected to the drainage system?
- Why is separation fabric installed between soil and drainage aggregate, and what happens if it is displaced during backfill?
- What is the difference between the lawful outlet and the emergency overflow route, and why does each require separate verification?
- What must a controlled flow test confirm before a drainage installation may be considered complete?
- Why is backfill placed in lifts with light firming rather than compacted heavily in one pass?
- What must happen before any trenching begins under this chapter?
- Why does a flat or reverse-sloped section of trench bottom cause a drainage failure even if the pipe itself is undamaged?
- What must be documented on the Drainage Installation Record before this chapter is considered closed out?
Competency Rubric
| Competency | Independent Pass Standard | Not Demonstrated | With Assistance | Independently |
|---|---|---|---|---|
| LS-091 | Identifies water-collection points from the drainage plan and site observation and confirms the wet-area cause is suitable for a landscape drain | |||
| LS-092 | Lays out the drainage path and establishes invert elevations and required fall before excavation | |||
| LS-093 | Excavates a stable trench and installs separation fabric and a gravel bed to the approved specification | |||
| LS-094 | Installs perforated or solid drain pipe in the specified orientation with fully seated fittings and continuous fall | |||
| LS-095 | Routes discharge to a confirmed lawful outlet, protects the outlet, and establishes an emergency overflow route | |||
| LS-096 | Performs a controlled flow test and inspects and documents collection, pipe flow, leaks, ponding, outlet, erosion, and overflow |
Mark one column per competency. Only Demonstrated Independently awards the competency; Demonstrated with Assistance authorizes additional supervised practice but does not complete the requirement.
Inspection Checklist — Drainage Installation Record
| Section | Completed (Y/N) | Deficiencies Found | Resolution |
|---|---|---|---|
| Cause Confirmation | |||
| Utility and Boundary Verification | |||
| Layout and Invert Elevations | |||
| Trench and Fabric | |||
| Pipe and Fittings | |||
| Outlet and Overflow | |||
| Backfill and Grade | |||
| Controlled Flow Test |
Installation status: ______ (Approved / Conditional / Rejected) Date: ____________ Installer name: ____________
Performance Check
With the drainage system backfilled and the flow test complete, review the finished installation against the Acceptance Standards table and confirm the wet-area cause was suitable for a landscape drain, utility locating and discharge verification were completed before excavation, invert elevation falls continuously from inlet to outlet, the trench and pipe meet the approved specification, the outlet is lawful and protected, the overflow route avoids prohibited discharge points, and the controlled flow test passed without leaks or unexpected ponding. If any deficiency remains, correct it and repeat the affected check before recording the final installation status.
Project Closeout
You have completed a landscape-drainage installation for a residential wet area. This chapter required you to identify water-collection points (LS-091), lay out the drainage path (LS-092), install a gravel trench (LS-093), install perforated drain pipe where appropriate (LS-094), route discharge safely (LS-095), and inspect drainage performance (LS-096).
You now have a supported, accessible drainage system that captures water at the identified inlet, carries it on continuous fall to a lawful and protected outlet, provides an emergency overflow route, and has passed a documented controlled flow test. That verified drainage condition carries forward into Chapter 17 pruning and Chapter 18 fertilizing and maintenance work in the same area, into Chapter 19 restoration where drainage function is reverified, and into the Chapter 20 capstone project.
Store your completed Drainage Installation Record, invert-elevation readings, and flow-test photographs where every later chapter can reference them. Chapter 17 begins from the corrected, drained condition documented in this chapter.