Drainage Systems, Retaining Walls & Erosion Control

Drainage, Retaining Wall Bases & Erosion Control for Calgary Properties

Water that goes the wrong way is behind many wet basements, leaning walls, washed-out approaches and gullied slopes in and around Calgary. This is the excavation that puts water back where it belongs: drains at the footing and across yards, the base and drainage under retaining walls, culverts and ditches on acreages, and the earthwork that holds slopes together.

A trench dug along a new concrete foundation wall holds black perforated drain pipe in a white filter sock on clean crushed stone, with soil on a tarp and a compact excavator at the far end.

What This Work Covers

Every service in this group is drainage excavation at heart; what changes is where the water is and what it is damaging. French drain and weeping tile excavation deals with groundwater at the house: digging to the footing, replacing failed tile with perforated pipe in clear stone and filter fabric, and sending the water to the surface or the storm system, never the sanitary sewer. Retaining wall base excavation deals with water and soil pressure behind a wall: we dig the base, compact the levelling pad and place the drainage, and a wall builder builds the wall. Culvert installation and ditch re-grading deal with water crossing acreage driveways and running along roads. Slope stabilization and erosion control deal with water running over and through sloping ground.

The work differs in who controls it. Foundation drainage in Calgary is governed by the City's lot drainage rules and Stormwater Bylaw, including a minimum 4% slope within 1.2 m of the foundation. Retaining walls in Calgary need a building permit at 1.2 m of retained soil, with engineer-stamped plans, while the City's own pages disagree on whether the development permit trigger is 1 m or 1.2 m. Culverts in County rights-of-way need County permission, and new or upgraded approaches are inspected by the County; in Rocky View County, approach culverts cannot be less than 450 mm in diameter. Erosion and sediment control on Calgary construction sites is set by site size under the City's Code of Practice.

The work also differs in who designs it. A like-for-like weeping tile replacement or a yard French drain is usually laid out on site from what the excavation reveals. A tall or gridded retaining wall follows a manufacturer's installation guide or an engineer's drawing. A culvert's size comes from the County approval or an engineer. A slope that has moved needs a geotechnical engineer, and a larger construction site's ESC Plan is prepared by a Qualified Designer. In every case Aspen Excavating does the digging, grading, compaction and placement of drainage and base materials; the design, the wall, the pump and the plumbing belong to the people qualified for them.

Drainage & Erosion Control Services

A mini excavator parked beside a sloped excavation along the back wall of an older stucco house, with the concrete foundation exposed and soil stockpiled on tarps.

French Drain & Weeping Tile Excavation

Digs to the footing, new perforated tile in clear stone, and yard French drains.

How it works

A straight base trench filled with levelled crushed gravel along a string line on wooden stakes, with a pallet of concrete wall blocks beside it.

Retaining Wall Base Excavation

Wall base trenches, compacted levelling pads and drainage. We dig; your builder builds.

How it works

An excavator rigs a corrugated steel culvert pipe with a sling beside a trench cut across a rural roadside ditch where a new driveway will cross.

Culvert Installation & Ditch Re-Grading

Acreage driveway culverts, approach approvals, riprap ends and ditch re-grading.

How it works

A freshly graded slope covered in brown erosion control blanket, with a line of black silt fence staked along its foot.

Slope Stabilization & Erosion Control

Runoff diversion, benching, riprap, silt fence and revegetation on slopes and banks.

How it works

Choosing Between Them

Water inside the basement: Damp at the base of the walls or water at the wall-floor joint often points to failed weeping tile, though grading that runs toward the house can add to it. Start with French drain and weeping tile excavation, but rule out a sewer backup through the floor drain first, which is a plumbing issue.
A yard that will not hold its shape: Calgary caps finished lot slopes at 33%, so where the grade has to change more steeply than that, a wall is often the answer. Choose retaining wall base excavation, and hire a wall builder for the wall itself.
Water crossing or ponding at a driveway: On an acreage, meltwater running over the approach or pooling beside it points to the culvert and the ditch. Choose culvert installation and ditch re-grading, and start with the County approval.
Soil moving downhill: Gullies, cracks at the top of a bank or sediment washing off a building site call for slope stabilization and erosion control. If the slope has actually moved, a geotechnical engineer assesses it before any excavation.

Why It Matters Around Calgary

Calgary's June 2013 flood was the largest in the city since 1897, and the City lists overland flooding, rising groundwater, stormwater back-up and sewer back-up among its causes of damage. Mission was among the first communities to flood and one of the first evacuated, and even where a temporary barrier helped, some properties in Mission and the Beltline were still affected by stormwater and groundwater seepage. That is the whole category in one event: surface water that needs grading and drainage paths, groundwater that needs working foundation drains and sumps, and sediment that needs controlling. The City's Regulatory Flood Map still sets floodway and flood fringe zones along the Bow and Elbow Rivers and Nose and West Nose Creeks.

Outside the city the water story changes with the terrain. Airdrie's own history page describes Nose Creek being dammed and the surrounding area as often wet and prone to seasonal flooding, a reminder that drainage there is nothing new. In Okotoks, the Sheep River valley runs north to south through the town as a wildlife corridor, so the valley and its edges are part of the town's landscape rather than something outside it. Each of these is its own municipality with its own permits, so drainage, wall and slope work starts with the City of Airdrie or the Town of Okotoks rather than with Calgary's rules.

Drainage & Erosion Control: Common Questions

Which should come first: drainage, a retaining wall or regrading?

Drainage and grading usually come first, because a wall or a slope repair built without them inherits the same water problem. The usual order is to fix water at the house (downspouts, weeping tile, sump discharge), establish grades that shed water away from buildings, then build any retaining wall on a base with its own drainage, and finish with topsoil, cover and erosion control. On acreages, the culvert and ditch come before the driveway is finished over them. Doing the work out of order usually means digging up something new.

Do you design drainage systems and slope repairs, or just build them?

We build them. Aspen Excavating excavates, grades, compacts and places drainage and base materials, and we lay out straightforward work such as tile replacement and yard drains from what the site shows. Anything that needs design is designed by someone qualified: a geotechnical engineer for slopes that have moved, an Alberta professional engineer for retaining walls that need stamped plans, a Qualified Designer for a City ESC Plan, and the County or an engineer for culvert sizing. We work to those drawings and flag anything on site that does not match them.

Can drainage and erosion work be done in a Calgary winter?

Some of it can, with limits. Calgary frost typically reaches around 2 m, and the City reported 2.4 m in the severe winter of 2019, so winter digging means breaking frozen ground first. Frozen soil cannot be counted as shoring, buried utilities still have to be exposed by hand or by an accepted non-destructive method, and City specifications do not allow frozen material as trench backfill. Seeding and establishing vegetation must wait for the growing season. Excavation to footings and culvert crossings can be done in winter; finished grading and revegetation are typically left for spring.

Other Excavation Services

Site Prep & Earthmoving

Foundations & Basements

Trenching & Hydrovac

Demolition & Removal

Commercial & Specialized

Talk to Us About Drainage & Erosion Control

Tell us about the site, what is there now and what is going in. We will recommend the scope that fits, including when a smaller job will do.

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