Pond, Dugout & Retention Basin Digging Near Calgary

The Problem It Solves

Many dugouts and ponds that fail do so for reasons that were in the ground before the first bucket went in. A seam of sand or gravel a metre below the planned bottom lets the water drain away as fast as spring runoff fills it. A dugout dug too shallow can lose a large share of its useful volume to evaporation in summer and to ice in winter, and Alberta’s own guidance notes that a deeper dugout is more efficient. Sides cut steeper than the soil will stand slump into the water after the first freeze-thaw cycle, shrinking the capacity and leaving a soft, undercut edge.

Then there are the rules. Plenty of acreage owners assume that a hole on their own land is nobody else’s business, and for many ordinary dugouts under Alberta’s Water Act that is close to true, because they are exempt from approval. But the exemption has hard edges. It does not cover a dugout bigger than 7,500 m³, one dug in a wetland or a fish-bearing watercourse, or one that would change the flow of water onto a neighbouring parcel. A purely decorative pond does not obviously fit the regulation’s definition of a dugout, and borrow pits get no exemption at all. Finding that out after the digging is finished leaves an owner seeking authorization for something already built.

The spoil causes its own damage. A dugout moves a great deal of soil, and dumped in the wrong spot it blocks the natural drainage path, pushes runoff onto a neighbour or a driveway, or buries a septic treatment field that nobody marked. On a subdivision or commercial site, a stormwater retention basin that misses its designed volume or outlet elevation does not store the storm it was built for, and the water ends up on downstream lots or roads instead.

How It Works

We start by finding out whether the ground will hold water. Before the dig is priced as final, we put in the test holes the provincial dugout guide calls for, at least five or six spread across the footprint and carried 1.2–1.5 m (4–5 ft) below the proposed bottom, and we log what each one shows: clay, silt, sand or gravel layers, seepage, and anything that will not hold. At the same time we walk the drainage path the pond will draw from and discharge to, mark the well, septic tank and field, and work out the capacity against the 7,500 m³ and 15,000 m³ limits so the size is decided with the rules in view.

The dig follows the shape agreed with the owner or the designer. Depth is set by what the water is for and what the test holes allowed; side and end slopes are cut to what the soil will stand, with historic prairie practice of 1.5:1 sides and 4:1 ends as the starting point unless a design says otherwise. Where test holes show a layer that will not hold water, the choices are to move the pond, stop above the layer, or have a designer specify a compacted clay liner, which we place in thin lifts and compact with a padfoot roller. Inlets and overflow outlets are shaped and armoured with riprap over geotextile so runoff does not cut them away.

Spoil goes where it does no harm. Topsoil is stripped first and kept aside to dress the finished banks and spoil areas, mineral soil is spread and shaped so it does not redirect water onto an adjacent parcel, and anything the site cannot use is hauled away. Retention basins are dug to the engineered drawings, with the bottom, side slopes, outlet structure and emergency overflow checked by survey against the design volume. The owner ends up with a pond that holds water, sits inside the rules, and has banks that stay where they were cut.

What Decides the Specification

Purpose sets the size and depth. A livestock dugout is sized to the herd and the months it has to last; a decorative pond is shaped for appearance and safety at the edge. Depth matters more than people expect: Alberta’s dugout guide says a deeper dugout is more efficient, since a shallow one typically gives up more of its volume to evaporation and ice, and it notes newer, larger dugouts being dug to about 4.6–6.4 m (15–21 ft). Where the water comes from matters too: a pond filled by spring runoff behaves differently from one topped up by pumping, and pumping water in changes whether the licence exemption applies.

The test holes decide the rest. Clay that holds water lets the dugout be dug to the shape planned; a sand or gravel layer, a wet seam or high seepage changes the depth, the location or the need for a compacted clay liner. Soil type also sets how steep the banks can safely be cut, and softer or sandier material needs flatter slopes than the historic 1.5:1. For a stormwater retention basin, the engineer’s design governs every dimension: the storage volume, the bottom and top-of-bank elevations, the outlet control, the overflow route and the side slopes, and our job is to build that surface accurately and prove it by survey.

Around Calgary

Bearspaw, in Rocky View County, spans parts of three drainage catchments, Big Hill Springs Creek, Nose Creek and the Bow River, and its area structure plan speaks directly about slopes, coulees, wetlands and riparian areas. That is exactly the ground where a dugout needs checking before it is dug: a low spot that looks like the natural place for a pond may be a wetland, where the dugout exemption does not apply, and a coulee bottom may carry runoff that a pond and its spoil would push onto the next parcel. The plan sets agricultural parcels at a minimum of 14.2 ha (35 acres), and parcels of that size are where a livestock dugout is more likely to fit.

Springbank, also in Rocky View County, has twelve stormwater catchment areas, five flowing north to the Bow River, and many comprehensively planned two-acre subdivisions in a community that has historically relied on groundwater wells, private water co-operatives and septic fields. On a two-acre lot, a decorative pond competes for space with the well, the septic tank and the treatment field, and spoil has very few places to go, so hauling is often part of the job. South of the city, around De Winton in Foothills County, the traditional acreages can be big enough for a dugout, but the County’s own permit statement means the conversation with the County comes before the dig.